Browse Topic: Frontal collisions

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Investigation into the Crashworthiness of Freight Vehicles under Frontal Impact2026-99-12869/4/2026
This paper investigates the crashworthiness of freight vehicles under frontal impact based on the C-NCAP (China New Car Assessment Program) standard. Explicit dynamics and finite element methods were employed to conduct simulation analyses of the impact event, with the aim of offering references for improving vehicle crashworthiness. The findings indicate that the vehicle cabin remains largely intact, providing sufficient survival space for occupants. However, increased load amplifies the impact impulse and reduces crashworthiness. Additionally, the use of an enhanced anti-collision beam helps distribute impact forces and lowers the peak impact load.
Liu, Zihan, Jiang, Yi, Wang, Pu
Pelvis Lap Belt Engagement of Small-Sized Females in Frontal Impacts Using Seat-Integrated Restraints and Vehicle Seats for Alternative Seating Positions2026-22-00088/14/2026
Non-traditional vehicle seating postures challenge traditional occupant protection paradigms that promote pelvis lap belt engagement. Seat-integrated restraints may promote pelvis lap belt engagement in alternative seating postures but have not been evaluated with post-mortem human subjects (PMHS) in vehicle seats. The goal of this research was to perform three 38.8 g, 56 km/h frontal impact sled tests with small-sized female PMHS in a crash environment with a vehicle seat designed for alternative seating positions. PMHS pelvis kinematics, lap belt engagement, and submarining response were compared to that of the Hybrid III 5th female (HIII-5F) in the same environment. The seat was in the rearmost seat track position, reclined 40° from vertical, and incorporated a leg rest, which elevated the feet off the floor. A seat cushion airbag (SCAB), large passenger airbag (PAB), shoulder belt pretensioner (SB P/T), and seat-integrated belt (BIS) were incorporated into the testing environment. The SCAB restricted initial downward translation of the pelvis and induced 7.7°–11.8°of initial pelvis rearward rotation. Lap belt loading of the abdominal soft tissue occurred in each test via three distinct interactions: (1) initial pelvis lap belt engagement followed by pelvis fracture and subsequent submarining; (2) lack of initial pelvis engagement and direct abdominal loading; (3) initial pelvis lap belt engagement followed by submarining. In a matched test environment, the HIII-5F did not submarine nor reproduce the entire lap belt pelvis interactions observed by the PMHS. Future research must develop better tools for predicting lap belt engagement in alternative seating positions.
Newman, Rachel, Shin, Jeesoo, Sochor, Sara, Morgan, Neal R., Gepner, Bronislaw D., Kerrigan, Jason R., Kim, Yongtae, Kim, Sung Rae
Collapse Strength and Crush Space Analysis in Lateral Side Pole Impact of an Electric Vehicle2026-01-50527/31/2026
High-Voltage Battery (HVB) protection in lateral pole impact is very important due to severe nature of the impact. Unlike frontal impacts, vehicles have limited range of space and capacity to absorb kinetic energy in lateral side impacts. Nowadays, computer-aided engineering (CAE) using finite element analysis (FEA) is utilized routinely to simulate high-speed crash events of varied type, including side pole impact. These CAE applications focus on the analysis and design of HVB when the vehicle structure is well-developed. CAE methods are time-consuming and are not suited during the pre-program stage when the structure is only in a concept stage and not even a reasonable CAD is available/developed in any sense to use these methods. There is no analytical tool available to understand how to define the characteristics of the structure that surrounds and protects the HVB. The primary motive of this publication is to help with this aspect of vehicle planning/development. Needless to state that this procedure can also be used in planning/developing of internal combustion engine (ICE) and hybrid vehicles, as well. The objective therefore is to develop a simple method/procedure that can give reasonably accurate estimation of the collapse/crush force required for a specified crush space and hence protect the critical components, such as HVB and fuel tank. This analytical method also gives some insight into the optimal use of the upper body (rocker and floor cross-members) and underbody (ladder frame) parts. It was found, for a problem under consideration, optimum kinetic energy to be absorbed by the upper body is 32.5% to avoid intrusion into HVB.
Alavandi, Bhimaraddi, Midoun, Djamal, Frank, Randy
Comparison of Female and Male Post Mortem Human Subject Kinematic Responses and Injuries in Rear-Facing Seat Configurations in High-Speed Frontal Impacts2026-22-00077/28/2026
This study investigates female post-mortem human subject (PMHS) responses and injuries, comparing them to previously published data from male PMHS tested at a change in velocity (delta-V) of 56 kph in high-speed rear-facing frontal- impact (HSRFFI) scenarios. Twelve small female PMHS were subjected to the same HSRFFI pulse. The subjects were positioned in reinforced production seats, identical to those from the previous male PMHS studies, and set to recline angles of either 25 or 45 degrees. Instrumentation was used to measure kinematics of the head, spine, pelvis, and ribs. Whole-body kinematics were recorded using motion capture. Female PMHS consistently showed lower head restraint, seatback, and lap belt loads compared to males across all test conditions (Bio Rank System [BRS] scores >1.0), with BRS scores for head restraint forces as high as 4.0. While head and T1 kinematics were consistent with males in all-belt-to-seat (ABTS) conditions (BRS < 1.0), significant differences were found in other body regions (BRS>1.0). Female PMHS had larger head forward rotation and smaller pelvis Z-axis displacement (less ramping) than males in the fixed D-ring (FDR) conditions, leading to major discrepancies (BRS>2.0). In addition, female chest deflection was smaller in one FDR condition (BRS=1.98), and tibia acceleration onset was earlier. Female PMHS sustained severe to critical rib fractures (Abbreviated Injury Scale [AIS]3-5) similar to males. However, five females in the FDR conditions and one in the ABTS condition sustained sacral fractures, an injury not seen in males. Females also had a higher frequency of lower extremity fractures (7 of 12) and vertebral body fractures (7 of 12) compared to males. These findings suggest that existing male PMHS data may not adequately predict responses and injury risks for female PMHS, emphasizing the need for female-specific biomechanical data to enhance safety tools and models in HSRFFI scenarios.
Kang, Yun-Seok, Baker, Gretchen H., Ramachandra, Rakshit, Marcallini, Angelo, Kwon, Hyunjung, Foster, Craig D., Moorhouse, Kevin, Agnew, Amanda M., Bolte, John H.
Geometric Deep Learning–Based AI Framework for Nonlinear Crash Behavior of Extruded Rails15-19-03-00127/27/2026
Extruded Rails are critical energy-absorbing components in automotive structures designed to mitigate impact loads during the frontal collisions. Traditional crashworthiness design relies heavily on computationally expensive finite element simulations and iterative design exploration. This work proposes a machine learning–driven framework for rapid front extruded rails design using a trained geometric deep surrogate model. A design-of-experiments (DoE) was conducted by varying geometric parameters including width, height, and wall thickness of a thin-walled extruded rail structure. For each design variant, LS-DYNA simulations were performed to obtain performance metrics such as mean crush force and peak crush force. These simulation results were used to train an AI surrogate model capable of predicting crash responses directly from geometric parameters. The proposed approach significantly reduces computational cost by replacing repeated high-fidelity crash simulations with machine learning surrogate predictions. By enabling fast and accurate evaluation of crash response metrics, the workflow shortens design cycles and supports sustainability-driven crashworthiness assessment by reducing simulation resource usage. The framework establishes a scalable, simulation-driven engineering pathway across vehicle platforms and provides a foundation for future closed-loop, AI-assisted crash design workflows.
Kumar, Manik, Srinivasan, Sriram
Female PMHS Thoracic Biomechanical Response Corridors with Preliminary Consideration of the Influence of Breast Tissue in Frontal Impacts2026-22-00066/24/2026
Thoracic injuries are common for belted occupants in frontal motor vehicle crashes. However, there remains a lack of female post-mortem human subject (PMHS) data in the literature to generate female-specific biomechanical response corridors and evaluate engineering tools such as anthropomorphic test devices (ATDs) and computational human body models (HBMs). Additionally, the effect of breast tissue on thoracic response has not been directly investigated despite female ATDs and HBMs having features representing breasts. As such, this study sought to utilize simplified frontal hub impacts to (1) generate female PMHS thoracic response corridors both with breasts positioned with a bra and without breasts (no bra) and (2) preliminarily explore the influence of breasts on the thoracic responses of female PMHS. Twelve female PMHS (9 small and 3 midsize) were subjected to frontal impacts at mid-sternum with a 14.0 kg circular impactor at 4.3 m/s in conditions with and without breasts. Force versus deflection (FD) response corridors were generated, and comparisons were made between groups and to scaled FD corridors representing female response. Overall, female PMHS with and without breasts displayed differences in FD response compared to scaled corridors in terms of the shape of the initial response and peak force and deflection. Additionally, female PMHS with breasts produced lower peak force and greater peak deflection compared to those without breasts. These results suggest the importance of collection and evaluation of female biomechanical data that can be used for continued evaluation of female-specific safety tools as well as the further reduction of injury risk for all occupants during motor vehicle crashes.
Baker, Gretchen H., Kang, Yun-Seok, Marcallini, Angelo, Lang, Ryan, Hutter, Erin, Moorhouse, Kevin, Agnew, Amanda M.
Occupant Sex Equity and Vehicle Safety: Historical Activities, Research, and Countermeasure2026-22-00025/28/2026
Since 2019, sex equity in traffic crashes has been a highly debated topic in vehicle safety, especially following the 2019 study by Forman et al. (1) claiming that female occupants face a 73 percent greater risk of serious injury in frontal crashes compared to male occupants. This was soon followed by a Consumer Reports Article by Keith Barry (2), which attempted to identify underlying factors contributing to the higher risk. These have been embraced by several parties since 2019. Firstly, it was alleged that vehicle design practice over the last four decades considered safety for the male population only and ignored that of the female as evidenced by the exclusive use of the mid-sized male Anthropomorphic Test Devices (ATDs) in Regulatory and Safety Ratings tests and not with an average sized female ATD. The absence of such an ATD for testing of vehicles “set the course for four decades’ worth of car safety design, with deadly consequences” (2). Secondly, although there is a recognition of the fact that Regulatory testing with a Small Female ATD, the Hybrid III-05F, was introduced in the FMVSS208 in 2003, this ATD was only a scaled version of the average male ATD of the 1970’s implying that this ATD is incapable of driving the design of restraint systems for females due to “They’re put together differently. Their material properties—their structure—is different” (2). Thirdly, according to a quote “These same trends have been observed in many, many studies in the past.” We assume that the trends refer to the apparent disparity in safety of females when compared to those of males. This document aims to outline historical activities, associated research and the development of countermeasures addressing crashworthiness concerns related to vehicle safety for females, as well as factors affecting both males and females, such as age-related impacts. This paper deals mainly with the frontal crash modes, mentions side impacts briefly as it affected designs of inflatable restraints for side impact to protect the smaller portion of the population from inflation induced injuries but the history behind the use of female ATDs by IIHS and NHTSA in full scale testing is not covered. Where ever possible, the time periods of reported activities related to female safety have been divided to pre-1997 corresponding to a change in US frontal crash regulation to address serious-to-fatal injuries to females and children, between 1997 to 2003 corresponding to the proposal by Canada for its frontal impact standard, and between 2003 and 2006 when the Advanced Restraint Regulation in the US FMVSS 208 was promulgated. This was followed by activities between 2007 and 2019, and post 2019 period.
Prasad, Priya, Dalmotas, Dainius J.
Characterization of Front Row Occupants Involved in Motor Vehicle Crashes Compared to ATDs and the U.S. Population09-14-01-00275/4/2026
Currently, adult anthropomorphic test devices used in regulatory and consumer information crash testing in the United States are targeted to represent a small female (5th percentile) and an average male (50th percentile). The anthropometry determined previously might not represent the current population, or as investigated in the current study, those that are at least moderately injured during a motor vehicle crash. The objective of this study was to use field data to determine if the current frontal anthropomorphic test devices are representative. Data from the National Automotive Sampling System–Crashworthiness Data System (2010-2015) and Crash Investigation Sampling System (2017–2023) were queried for sex, age, size, and injury information for front seat occupants in frontal crashes. Additional datasets used were from the National Trauma Data Bank and the Centers for Disease Control and Prevention. According to field data, the most frequently injured female and male is approximately 164 cm tall, weighing 72 kg and approximately 177 cm tall, weighing 81 kg, respectively. The distribution of those injured in frontal crashes aligns with all crash types and the current United States population. Differences between anthropomorphic test device specifications and recent data (particularly weight) should be the focus of future work.
McNeil, Elizabeth, Atwood, Jonathan, Rudd, Rodney, Craig, Matthew
Frontal Crash Classification and Occupant Outcomes from 2017 to 2023 US Field Cases09-14-01-00245/4/2026
This study provides an updated characterization of real-world frontal crash types—considering overlap and obliquity—based on their overall frequency and associated injury outcomes. The results of this study will support an evaluation of how well NHTSA’s frontal oblique crash test condition addresses the current population of serious frontal crashes, as compared to frontal test modes in existing crashworthiness programs. U.S. field crash data from 2017 to 2023 were analyzed to classify frontal crashes by coded damage characteristics. Oblique frontal crashes were defined as those with principal direction of force between 10°–40° and 320°–350°. Non-ejected belted first and second row occupants in model year 2000 and newer passenger vehicles absent a rollover event were included. Occupants were stratified by sex, age, and body mass index, and injury outcomes based on moderate, serious, and fatal thresholds were analyzed across crash configurations. Among the belted first row occupants considered in this study, more than 45% were exposed to oblique crashes while full overlap colinear crashes accounted for 18% of the occupants. Oblique crashes represent a disproportionately large number of AIS 3+ injured and fatal occupants. Older occupants and females showed a trend of higher injury frequency despite less exposure. Full overlap crashes still account for a representative portion of serious injuries among frontal crashes. Limitations include restriction of cases to those with complete vehicle and occupant details. Assessment of impact type was dependent on generic vehicle class-specific reference values. The findings reinforce the enduring relevance of oblique frontal crash conditions which remain a substantial contributor to serious injuries and fatalities, especially for older adults and female occupants.
Rudd, Rodney W.
Interactions of Rear-Facing Child Restraints in Frontal Crash Tests09-14-01-00105/4/2026
The aims of this study were to investigate the kinematics of child anthropomorphic test devices in a large sample of rear-facing child restraint system installations and the effects of anti-rebound features and load legs on the kinematics of rear-facing child anthropomorphic test devices. The test matrix included a general sample of 70 rear-facing child restraint system installations to observe trends in frontal crash tests; 14 full-scale crash tests with paired comparisons to investigate the effect of anti-rebound features; and five paired comparisons of rear-facing child restraint systems installed with and without a load leg. The paired t-test was used to determine the statistical significance of differences in kinematic responses. In the general sample, 84% of anthropomorphic test devices in infant seats with the base in outboard seats interacted with the first-row seat. In 52% of tests, the anthropomorphic test device head directly contacted the front seatback. Head accelerations > 80 g were caused by interactions between: the child restraint system and front seatback; the anthropomorphic test device head and the interior surface of the child restraint system; or the anthropomorphic test device head and front seatback. In the anti-rebound sample, head contact on rebound occurred in three infant seat installations, and all were associated with head resultant accelerations ≤33 g. The mean paired difference in head 3 ms clip was negligible (p > 0.05). In the load leg sample, the load leg limited forward excursion and forward rotation of the rear-facing child restraint system, thereby contributing to the containment of the anthropomorphic test device within the boundary of the child restraint system shell. In this study, anti-rebound features did not improve the kinematics of pediatric anthropomorphic test devices. The feasibility of including the use of the load leg in the Canadian regulatory test protocol should be explored.
Tylko, Suzanne, Tang, Kathy
The Effect of Initial Foot Position on THOR-50M and THOR-05F Lower Leg Response in a Realistic Vehicle Buck09-14-01-00085/4/2026
This study aims to explore and evaluate the effect of various foot positions on the kinematic and kinetic response of the lower extremity during frontal crashes using a realistic vehicle interior. Frontal impact sled tests were performed with the Test Device for Human Occupant Restraint, 50th-percentile Male (THOR-50M) and Test Device for Human Occupant Restraint, 5th-percentile Female (THOR-05F) anthropometric test device (ATD) in the driver’s seat of a midsize SUV testing buck (with realistic interior components including an instrument panel with steering wheel and steering wheel airbag, seat, three-point seat belt with pretensioner and force-limiter, accelerator pedal, brake pedal, knee airbag, and seat belt retractor pretensioner). Six sled tests were performed in two principal directions of force (PDOF) [three each in frontal (0°) and oblique (−20°) configurations]. The right foot was positioned on the accelerator pedal, fully on the brake, and half on the brake. A single test was conducted with the THOR-05F in an oblique configuration with the foot on the accelerator. Ankle response was analyzed from internal ATD instrumentation. Restraint engagement was found to be consistent across all testing cases. Ankle moment and angle varied based on PDOF and the tested foot condition. Right ankle moment ranged from 70 to −70 Nm in inversion/eversion. Right ankle angles ranged from 37° inversion to 28° eversion. Left ankle moment ranged from 10 to −41 Nm in inversion/eversion. Left ankle angles ranged from 10° eversion to 23° inversion. Differences in lower extremity motion and loading were observed for each testing condition. Placing the foot on the accelerator pedal produced greater ankle moment than either brake pedal condition. Placing the foot on the brake pedal resulted in the highest dorsiflexion angle response. Obliquity increased ankle moment and rotation for both ankles. The United States New Car Assessment Program (US-NCAP) foot position with an oblique PDOF created the highest ankle moment while the in-line brake position in oblique created the highest dorsiflexion rotation. By combining these findings with other efforts focused on naturalistic driving and foot positioning, these results might aid in development of additional testing practices that might enhance our understanding of the lower extremity in nonstandard initial positions.
Noss, Junior, Donlon, John-Paul, Morris, Anna, Samier, Germain, Park, Joseph, Forman, Jason
Front-Row Seatback Contact for Pediatric Occupants Seated in Rearward-Facing Infant Child Restraint Systems during Frontal Crashes09-14-01-00195/4/2026
Using a subset of the Transport Canada dataset of rearward-facing CRS in full-frontal rigid barrier vehicle tests, the aim of the current study was to evaluate CRS and/or ATD head contact with the front-row seatback and categorize the contribution to the peak ATD head acceleration. For 33 cases of ATDs seated in rearward-facing CRS models installed in the second-row outboard seats across 19 vehicle tests, high-speed video footage was analyzed to identify instances and timings of CRS and/or ATD head contact with the front-row seatback. The timing of contact was compared to the ATD head acceleration time history to identify instances of “contributory contact” with the front-row seatback, which was defined as contact occurring before the ATD head acceleration was within 10 g of the peak. ATD contributory contact cases involved both the ATD head and CRS contacting the front-row seat, whereas CRS contributory contact cases involved only the CRS, but not the ATD head, contacting the front-row seat. No contributory contact cases were those that involved either ATD or CRS contact with the front-row seatback, but the contact occurred after the time point associated with 10 g below the peak ATD head acceleration. No contact cases were those that did not involve either ATD or CRS contact with the front-row seatback. Contributory CRS and/or ATD contact with the front-row seatback was found to be associated with increased head injury risk. Therefore, the energy-absorbing properties of the CRS head restraint and/or front-row seatback are likely important considerations regarding frontal crash protection for rearward-facing pediatric second-row occupants. Impact velocity, location, and angle were able to be calculated for two cases that involved contributory ATD contact with the front-row seatback. Such data could be used as boundary conditions for physical testing of front-row seatbacks and computational modeling.
Patton, Declan A., Tang, Kathy, Tylko, Suzanne, Arbogast, Kristy B.
Comparative Analysis of Thoracic Injury and Causative Factors across Sexes in Serious Frontal Motor Vehicle Collisions in the Crash Injury Research and Engineering Network Database09-14-01-00315/4/2026
This study investigated sex-specific differences in thoracic injury prevalence, causation, and rib fracture patterns among seriously injured occupants in frontal motor vehicle collisions. Crash Injury Research and Engineering Network (CIREN) data from 2005 to 2022 included 793 front-seat occupants aged 16 years and older with Abbreviated Injury Scale 2+ thorax injury, representing 1802 thoracic injuries. Injuries were grouped as rib fracture, sternum fracture, hemo/pneumothorax, lung injury, heart injury, and other. A weighted scoring system captured contributions of involved physical components to each injury. Logistic and linear regression with generalized estimating equations assessed sex associations with injury presence and causation. Two models were estimated: a comprehensively adjusted model including demographic, crash, vehicle, restraint, and airbag deployment, and a simplified model adjusting for age, body mass index, delta-V, and occupant role. Among occupants with AIS 2+ thoracic injuries, sex-specific differences were observed in injury patterns and causation. Females were less likely than males to sustain lung injuries (OR = 0.70, p = 0.038) and more likely to sustain rib fractures (OR = 1.25, p = 0.006). Females had higher odds of rib fractures attributed to seatbelt loading in both models (Full: OR = 2.20, p = 0.005; Simplified: OR = 1.55, p = 0.021). Females were less likely than males to sustain lung injuries (OR = 0.17, p = 0.042) and hemo/pneumothoraces (OR = 0.15, p = 0.044) from instrument panel loading. Steering wheel, airbag, and other components showed no significant sex-specific associations with thoracic injury. Rib fracture patterns showed clusters along the seatbelt path in belted occupants and a more diffuse pattern in unbelted occupants, with minimal significant findings of differences between sexes. These findings contribute to the growing evidence of sex-specific injury patterns and may inform future research on injury prediction and prevention strategies. However, this dataset includes only occupants with AIS 2+ thoracic injuries and therefore cannot be extrapolated to the general population or to collisions outside those represented in the sample.
Armstrong, William, Devane, Karan, Hsu, Fang-Chi, Heilmann, Nina, Sink, Joel, Miller, Anna N., Kiani, Bahram, Martin, R. Shayn, Stitzel, Joel D., Weaver, Ashley
Regional-Specific Patterns of Abdominal Injury in Belted Male and Female Frontal Crash Occupants: Insights from Redefined Anatomical Mapping09-14-01-00025/4/2026
Research Question/Methods The study examined abdominal injuries of 87 belted occupants in CIREN frontal crashes for sex-based differences in abdominal injury patterns. It introduced a more anatomically detailed method for identifying injury locations in an abdominal-pelvic region that includes skeletal structures. The study introduces and applies a novel Abdominal New Injury Severity Score (AbNISS) to address limitations of traditional AIS coding in capturing sex-based differences in injury patterns. The operative reports/EDR/imaging data in CIREN cases enabled identification of sex-specific crash outcomes. The dominant analytical motif is Bertrand Russell’s knowledge by acquaintance and definite descriptions. Results Females had a higher rate of moderate to severe abdominal injuries than males: Only females sustained AIS 5 injuries, lumbar Chance fractures, posterior pelvic arch injuries, and more AIS 2, 3, and 4 injuries, with more injuries in superior-mid, left-superior, and medial-mid-abdominal zones. Males had more in the medial-inferior zone. 13 females had muscle ruptures. Four had combined muscle and Morel–Lavallée injuries, and four had Morel–Lavallée injuries alone. 13 of 14 males had muscle ruptures only. Pelvic morphology: Statistically significant (p < 0.05) sex-based difference in pelvic aspect ratios: Females: 1.37 ± 0.053, with the male ratio of 1.28 ± 0.079. By incorporating anatomical precision and enhanced injury mapping, it supports the development of more representative ATD/human body models. Discussion and Limitations Limitations of the study include its retrospective design, possible inconsistencies in clinical documentation, and challenges in applying AbNISS coding to non-CIREN datasets due to specificity constraints.
Halloway, Dale, Curry, William, Somasundaram, Karthik, Pintar, Frank
Injury and Kinematics of Obese PMHS in Frontal Impacts with Reclined Seating09-14-01-00035/4/2026
Objective: This study investigated injury outcomes and body kinematics in obese occupants exposed to frontal impacts while seated in reclined postures. With increasing interest in non-traditional seating configurations and a growing population of obese vehicle occupants, the objective was to evaluate how seat stiffness and restraint features influence injury patterns and whole-body excursions. Methods: Nine obese post-mortem human surrogates (PMHS; mean age: 64 years, stature: 1.70 m, body mass: 102 kg, BMI: 35 kg/m2) were tested under frontal impact conditions simulating a delta-V of 50 kph. All specimens were seated on a spring-controlled seat with a 45° reclined seatback and restrained by a three-point belt system with pretensioner and load limiter. Three configurations were evaluated: (1) stiffer seat, (2) softer seat, and (3) stiffer seat with a knee bolster 100 mm from the knees. Each subject underwent one test. Whole-body kinematics were captured using a VICON motion analysis system, and injury outcomes were assessed through radiographs, CT imaging, and autopsy, with severity classified by Maximum Abbreviated Injury Scale (MAIS) and Injury Severity Score (ISS). Results: Softer seats produced substantially greater downward (+Z) pelvic displacement compared with stiffer seats. The knee bolster effectively reduced both downward and forward excursions of the lower torso. Rib cage and pelvic injuries were most frequent, with the highest severity observed in softer seat tests. Mean ISS values were: STIFF—27, 13, 27; SOFT—34, 27, 14; STIFF-KB—22, 0, 13. Discussion: Reduced seat stiffness combined with increased occupant mass contributed to greater excursions and anterior torso injuries, whereas the knee bolster mitigated excursion and injury severity. Findings are limited by sample size and test conditions; broader evaluation with production seats is needed to confirm trends and support countermeasure design.
Somasundaram, Karthik, Yoganandan, Narayan, Pintar, Frank
Geometric Variabilities and Their Effects on Impact Responses in Midsize Male and Female Occupants09-14-01-00255/4/2026
The objective of this study is to use parametric human body models (HBMs) to understand how geometric variability among individuals who have the same sex, stature, and body weight may affect the impact responses and injury outcomes, using midsize male and midsize female populations as representative cases. Methods were developed to quantify skeletal and external body surface variations using principal component analysis, regression, and residual error analysis. Based on this analysis, nine midsize male and nine midsize female geometric models were created, focusing on ribcage and pelvis variations, which account for most of the observed variability. These geometries were then applied to morph the simplified Global Human Body Model Consortium (GHBMC) midsize male model, producing 18 distinct HBMs. Each morphed HBM was subjected to nine impact scenarios, resulting in a total of 162 simulations to assess the effects of geometric variability. Substantial geometric variation was observed in the ribcage and pelvis, while the femur and tibia showed minimal variability for both midsize males and females. All morphed HBMs had good mesh quality, and all crash simulations terminated normally without error. Component-level tests showed relatively minor differences in impact responses among HBMs with identical sex, stature, and body weight. However, the United States New Car Assessment Program (US-NCAP) frontal crash simulations revealed considerable differences in injury risk, especially in the front passenger position. These findings highlight the importance of accounting for geometric variability, even among HBMs with the same sex, stature, and body weight, when evaluating injury risks in severe frontal crashes. It is especially important to consider ribcage geometry variations, which could impact occupant sitting height, posture, and injury risks at different body regions in frontal crashes. This study demonstrated that future virtual testing frameworks using HBMs should consider human geometric variations, especially in the ribcage and pelvis, when assessing injury risks in vehicle frontal crashes.
Hu, Jingwen, Lin, Yang-Shen, Boyle, Kyle, Khandare, Sujata, Bonifas, Anne, Reed, Matthew P., Hasija, Vikas
Assessing Injury Prediction with Human Body Models: Application to Rib Fracture Risk Prediction Using SAFER HBM09-14-01-00235/4/2026
As a consequence of the introduction of mathematical human body models (HBMs) in consumer information programs, there is an increased need for reliable methods that can demonstrate and build trust in the capability of HBMs to predict human response and injury risk in crashes. Therefore, a framework for validation of strain-based injury prediction is proposed. The framework comprises stepwise validation with the final step to validate the utility of risk predictions by means of the area under the curve (AUC) combined with Brier scores. SAFER HBM V11.1.0 previously validated at component and body part levels was selected for the demonstration of the final step of the framework to validate the capability to predict fracture risk in frontal, oblique, and lateral loading. For frontal loading, five postmortem human surrogate (PMHS) test series with 43 PMHS (age range: 19–88 years) were reconstructed. The predicted rib fracture risk for 2+ and 3+ fractured ribs was compared to the number of fractured ribs sustained by the PMHS. Using the framework, the SAFER HBM was for frontal impact analysis found capable of predicting 2+ fractured ribs with an AUC of 0.90 and 3+ fractured ribs with an AUC of 0.89. For oblique and lateral impacts, three PMHS test series including 47 PMHS (23 with 0, 22 with 2+, and 20 with 3+ fractures) were reconstructed, and SAFER HBM rib fracture risk predictions obtained AUC values of 0.84 and 0.87 for 2+ and 3+ fractured ribs, respectively. In the frontal load case, the Brier score was 0.14 for the Number of Fractured Ribs (NFR) 2+ model and 0.17 for the NFR 3+ model. In the lateral/oblique load case, Brier scores were 0.20 and 0.18 for the NFR 2+ and NFR 3+ models, respectively. The proposed framework is a suitable method to objectively assess the utility of HBM injury predictions, demonstrated with the SAFER HBMs capability to predict rib fracture risk.
Pipkorn, Bengt, Niranjan Poojary, Yash, Osth, Jonas, Larsson, Karl-Johan, Iraeus, Johan
Biomechanical Responses and Injuries of Male Post-Mortem Human Subjects in Rear-Facing Frontal Impacts with Unreinforced Airbag-Equipped Production Seats09-14-01-00305/4/2026
Previous rear-facing post-mortem human subject (PMHS) studies utilizing a reinforced seat have prompted questions as to whether the seat could have been a contributing factor to the severe rib and pelvis injuries observed in those experiments. In response, a recent PMHS study used an unreinforced seat in a similar experiment, which was expected to mitigate severe injuries by dissipating energy from seatback deformations. However, the PMHS tested in the unreinforced seat sustained even more severe rib fracture numbers than in the reinforced seat. No studies have investigated how additional variables (i.e., countermeasures) may influence rib fractures in high-speed rear-facing frontal impacts (HSRFFI). Therefore, this study aimed to explore the effect of an airbag-equipped seat (AES) on male PMHS responses and injuries. Rear-facing sled tests were conducted using five mid-size male PMHS seated in the AES at ΔV of 56 km/h: PMHS1 with no airbag as a baseline, PMHS2 with a seatback airbag (SA), PMHS3 with an extended seatback airbag (ESA), and PMHS4 and 5 with ESA and a wedge airbag (ESA+WA). An instrument panel (IP) and windshield were installed behind the seat to mimic realistic interior vehicle compartments. A chestband at mid-sternum, 6-degree motion blocks at the head, T1, T4, T8, T12, pelvis, and extremities, as well as rib strain gages and rosettes were installed on PMHS to understand potential mechanisms of injuries. A motion capture system was used to quantify whole-body PMHS and seatback kinematics. Maximum seatback rotation was 38.1° in the baseline test and 20.3°–25.1° with AES. Peak chest A-P compression in the anterior-posterior (A-P) direction was 25.7 mm for baseline and 7.3 mm–35.2 mm with AES (23.7 mm for SA, 7.3 mm for ESA, 35.2 and 8.7 mm for ESA+WA). The number of rib fractures (NRF) was high in baseline (32), SA (25), and ESA (27) conditions, but was reduced in ESA+WA (6 and 13). Strain rosette data indicated upward directions of principal strains on the posterior ribs, likely due to I-S deformation of the PMHS thoraces. Responses from thorax instrumentation showed that peak chest deflection (A-P) alone did not fully explain NRF, especially as rib fractures in all tests occurred after peak deflection in this direction. Instead, maximum principal strains in the I-S direction (shear), confirmed by strain rosette data, likely influenced rib fractures. ESA+WA effectively supported PMHS, maintaining upright postures and minimizing I-S chest shear, which reduced NRF. Limitations include a small sample size, possible age-related injury effects, and seat designs intended for low-speed rear impacts, not HSRFFI. Compression and shear loading to the PMHS thoraces were observed in HSRFFI. The shear loading was likely due to the large upward thorax deflection induced by the ramping motion and seatback rotation. One of the AES, ESA+WA, effectively maintained an upright spine and reduced NRF. This study offers important information for improving current safety tools and designing rear-facing countermeasures for automated driving systems.
Kang, Yun-Seok, DeWitt, Timothy, Wensink, Timothy, Marcallini, Angelo, Jung, Yong Hyun, Lee, Dong Gil, Harm, Jae Jun, Ko, Seokhoon, Hunter, Randee, Agnew, Amanda M.
Effects of Child Anthropometry, Seatback Angle, Seat Rotation Angle, Seatbelt Force Limiting, and Collision Type on Injury Risk of Child Occupants in Highly Automated Vehicles2026-01-05704/7/2026
This study aimed to evaluate the influence of child anthropometry, seating postures (recline and rotation), seatbelt force limiting, and frontal collision scenarios on the kinematic response and injury risk in highly automated vehicles. The TUST IBMs 6YO-O model was conducted the frontal collisions in sled tests. This simulation matrix includes five percentiles six-year-old occupants (P3, P25, P50, P75, and P97), three seatback angles (20°, 30°, and 45°), four seat rotation angles (0°, 90°, 180°, and 270°), three seatbelt force limiting (2.6 kN, 3.6 kN, and 4.6 kN), and three frontal collision types. Injury risks were assessed including the child occupant's head, neck, chest/abdomen, and lumbar region in each simulation (n=540). The results indicate that the child anthropometry, the seatback angle, and the seat rotation angle have a significant influence on the motion responses. Statistically significant differences between all the groups within each independent variable category were observed based on the analysis of variance. As the child dimension increases, the risk of head injury decreases showing by HIC15, while the risk of neck and lumbar injuries increases. As the seatback angle increases, biomechanical parameters of the head show an increasing trend. The risk of upper neck injury decreases, while the risk of lumbar injury decreases and then increases. As the seat rotation angle increases, the risks of head, neck, and chest injuries initially rise and subsequently decrease, while the risk of lumbar injury demonstrates a downward trend. Seatbelt force limiting exhibited a positive correlation with head, neck, and lumbar injury risks. Consequently, small percentile child experiences higher head loads in smart cockpits, with seatback angle and seat rotation angle being key factors contributing to child injuries. These findings highlight the critical need to address the vulnerability of smaller children in smart cockpits by adapting integrated active and passive safety systems to mitigate their injury risk.
Wang, Yanxin, Zhao, Hongqian, Li, Haiyan, He, Lijuan, Cui, Shihai, Lv, Wenle
Inertial Pedal Displacement and Brake Switch Activation in Frontal Crash Events2026-01-05414/7/2026
This paper presents research into the inertial displacement of brake pedals and the subsequent activation of brake light switches during crash events. In certain scenarios, such as multiple-impact crashes or crashes with pre-impact interactions such as curb strikes or sideswipes, inertial forces alone may generate sufficient brake pedal movement to trigger the brake switch, activating the brake lights. Such signals may be recorded by an Event Data Recorder (EDR) or observed by witnesses and incorrectly interpreted as an indication of intentional driver braking. To investigate this phenomenon, HYGE sled tests were performed using brake pedal assemblies and associated components from a Toyota Tacoma pickup truck and a Cadillac DeVille passenger sedan. The assemblies were subjected to acceleration pulses simulating a frontal impact, with high-speed video used to capture brake pedal displacement and brake light activation. The tests demonstrated that inertial loading from a pulse with a delta-V (change in velocity) as low as 12 mph could result in momentary brake light activation due to pedal displacement from inertial forces. Increasing the magnitude of the acceleration pulse produced greater displacement of the brake pedal and extended the duration of the brake light activation. An example is presented that demonstrates inertial pedal movement in a full-scale vehicle test conducted by striking a curb, which resulted in brake light activation with a delta-V considerably less than 12 mph. Additionally, a field survey of 50 passenger vehicles found that the brake switch activation threshold ranged from 0.25 to 0.56 inches of pedal travel for 80% of the vehicles measured. These findings indicate that relatively small crash accelerations and durations can produce sufficient inertial pedal movement to activate brake lights and that only minimal pedal displacement is required in most vehicles.
Walker, James, Duran, Amanda, Barnes, Daniel, Osterhout, Aaron, Clayton, Aidan
A Study on the Injury Risk of Occupant with Different Head and Neck Rotating Postures under the Frontal Impact Sled Conditions2026-01-05744/7/2026
Drivers obtain road information through head and neck rotation. In order to study the influences of head and neck rotation posture on occupant injury in frontal impact scenario, the THUMS (Total Human Model for Safety) AM50 human body model with five different head and neck rotation postures but without active muscles was adopted to study the biomechanical injury responses of occupant under the frontal impact scenario at 56 km/h in this study. Firstly, the kinematic responses of total body and head acceleration curves at the center of gravity predicted by PMHS (Post Mortem Human Subject) and THUMS AM50 human model under the sled test conditions were compared to verify the simulation model for subsequent study. Then, the THUMS AM50 human model with standard occupant seating posture was adjusted to have five different head and neck rotation postures with 0°, ±20°, and ±40° rotation angle, respectively. Finally, a series of frontal impact sled with or without airbag simulations were conducted for each THUMS AM50 human model with different head and neck rotation postures. The simulation results showed that with the increasing of head and neck rotation angle, the neck injury risk was increased while the thoracic injury risk was decreased. Regardless of whether airbags were present or absent, the model prediction for the standard posture indicated a lower injury risk. And regardless of whether the head and neck posture changed, the airbag always could provide a certain protection in that posture.
Li, Dongqiang, jiang, Yejie, Tan, Chun, Li, Yanyan, Gong, Chuangye, Wu, Hequan, Jiang, Binhui
Machine Learning Based Meta-Analysis of IIHS Moderate Overlap Frontal Crash Test for Rear Seat Occupant Safety Performance2026-01-05794/7/2026
A machine learning (ML)-based meta-analysis was conducted to evaluate rear seat occupant safety performance in the Insurance Institute for Highway Safety (IIHS) Moderate Overlap Frontal (MOF) 2.0 crash test. ML models were trained on historical IIHS crash test data to predict rear passenger injury metrics using vehicle architecture, restraint system characteristics, crash pulse parameters, and vehicle kinematics as input features. The models demonstrated high predictive accuracy and were subsequently used in a Sobol sensitivity analysis to identify critical design parameters influencing injury outcomes. The analysis revealed that rear passenger injury metrics were most sensitive to restraint system parameters. Specifically, crash pulse magnitude was the dominant factor for head injury metrics, pretensioner activation time for neck tension force, and lap belt force for the Neck Injury Criterion (Nij). For chest-related metrics—sternum deflection, dynamic belt position, and maximum belt position—the initial belt position emerged as the most influential factor. This study demonstrates the potential of ML models to uncover dominant injury mechanisms and critical design parameters without explicitly encoding biomechanical knowledge. The findings also offer actionable insights to guide future vehicle safety design improvements for rear seat occupants.
Lalwala, Mitesh, Kim, Wonhee, Furton, Lisa, Song, Jay
Occupant and Seat Responses in Various Moderate- to High-Speed Rear Impact Conditions: Focus on Head-to-Head Restraint Interactions2026-01-05654/7/2026
Head restraint requirements and designs have evolved to minimize the delay in head support and reduce differential loading in the neck. As a result, they have become bigger, closer to the occupant’s head, and angled forward relative to the seat back. Head restraints have been found missing or detached in the field; they may be removed pre-crash due to occupant comfort issues, or post-crash for better accessibility during extrication. Additionally, although rare, head restraints may become detached in severe rear impacts due to occupant loading. To better understand occupant-to-head restraint dynamic interactions, nine rear sled tests were conducted. The test conditions were selected to represent worst case severe loading scenarios. An instrumented 50th Hybrid III ATD (Anthropomorphic Test Device) was lap-shoulder belted on a right-front seat. The neck was equipped with a bracket and lower neck load cell designed for rear impacts. Three series of sled tests were performed wherein the kinematics and kinetics of a restrained ATD were compared across 3 seat configurations: a conventional modern seat, a rigidized modern seat, and an ABTS (all-belts-to seat). Occupant postures evaluated included seated nominally and leaning forward, as may occur in response to hard pre-impact braking and/or an initial frontal impact. Two crash severities were evaluated including a moderate speed (24 km/h delta V pulse based on Euro NCAP) and a very high-speed (49 km/h delta V) condition. Within each series, the sled pulse and ATD initial posture were held constant. The first series (Match #1) was conducted at 24 km/h with a leaned occupant. All biomechanical responses were below IARVs (Injury Assessment Reference Values). The highest responses relative to IARV were for upper and lower neck tension and extension. The Nij was greatest with the ABTS seat for upper neck and with the rigidized seat for lower neck, highlighting the importance of using both the upper neck and lower neck instrumentation. The second series (Match #2) was at 49 km/h with the nominally seated ATD, and the third (Match #3) was at 49 km/h with a leaning forward ATD. The biomechanical responses were below IARV when nominally seated. The biomechanical responses of Match #2 were more favourable than Match #3, highlighting the benefits of early energy absorption during the ride-down. For example, the upper neck Nij was 2.4 in the conventional seat, 4.2 in the rigidized seat and 5.1 in the ABTS. The corresponding lower neck Nij was 4.2, 5.5 and 2.3. The normalized chest 3 ms response was greatest in the rigidized seat, followed by the ABTS, irrespective of sitting posture. There are numerous reasons for an occupant to be out of position prior to a rear impact. In this study, the test conditions were selected to assess head-to-head restraint interactions in severe conditions, including leaning forward. Though the head restraints remained attached in all tests, the results provide insight on the seat and head restraint performance, and head and shoulder loading characteristics, in particular in some non-nominal postures.
Parenteau, Chantal, Burnett, Roger, Davidson, Russell
Injury Risk Analysis of Occupant with Different Lower Limb Postures under the Frontal Impact Sled Conditions2026-01-05724/7/2026
To investigate the characteristics of injuries sustained by occupant with different lower limb postures under the frontal impact sled conditions. Using the finite element method a series of simulation analyses were conducted on THUMS (Total Human Model for Safety) AM50 human body model with four different postures, including standing posture, lower limb bent at 100°, 90°, and crossed forward-backward, under the frontal impact scenario at 56 km/h in this study. The simulation results indicated that the overall injury risk predicted by the THUMS AM50 huma body model with lower limb crossed forward-backward was higher than that predicted by the model with other postures. The values of injury criteria including of HIC (Head Injury Criterion), head resultant acceleration, and thoracic VC (Viscous Criterion) predicted by the THUMS AM50 huma body model with lower limb crossed forward-backward were highest in these series simulations. Also, the biomechanical responses, including stress or strain of thoracic/abdominal organs, pelvic cortical bone and knee ligaments, predicted by the THUMS AM50 huma body model with lower limb crossed forward-backward was higher than these predicted by the model with other postures.
Li, Dongqiang, jiang, Yejie, Tan, Chun, Li, Yanyan, Li, Yihui, Wu, Hequan, Jiang, Binhui, Zhu, Feng
Pre-Crash Scenario Analysis and Generation for Integrated Safety System Virtual Testing with Real Accident Data2026-01-00624/7/2026
Integrated active and passive safety protection systems have made substantial contributions to reducing traffic accidents and mitigating human injuries. However, assessing such systems through vehicle collision tests is limited, as this approach cannot cover the wide range of accident scenarios. To address this gap, identifying and generating representative pre-crash scenarios from real-world accidents provides key boundary conditions for the setup of virtual test scenarios. In this study, we used the Future Mobile Traffic Accident Scenario Study (FASS) dataset to reconstruct 112 two-wheeler accidents. For each case, we extracted pre-crash dynamic information, static attributes, and environmental context. An autoencoder was employed to encode high-dimensional features of scenarios, and K-means clustering was applied to categorize the accidents into eight representative pre-crash scenarios. For each scenario, we examined the motion states of participants and further compared the behaviors and injuries between motorcycle and bicycle accidents. The results show that motorcycles have a higher average pre-crash speed than bicycles (22.4 vs 16.2 km/h), resulting in a greater proportion of Maximum Abbreviated Injury Scale (MAIS) 4+ cases (35.6% vs 18.9%). Furthermore, a Gaussian Mixture Model was applied to fit the scenario features. This model was then used to randomly generate the initial conditions of pre-crash scenarios, including the positions, speeds, and yaw angles of vehicles and two-wheelers. The proposed scenario generation method was first applied to pre-crash scenario construction for integrated safety systems tests, and it can create diverse, statistically grounded scenarios that reflect real-world accident distributions. These scenarios can broaden the test scope of integrated safety systems and support their implementation.
Wang, Guojie, Gao, Xin, Liu, Siyuan, Liu, Jiaxin, Li, Quan, Shi, Liangliang, Nie, Bingbing
High Biofidelity Modification of Thoracolumbar Structure in THOR Model for Reclined Occupant2026-01-01964/7/2026
With the rapid development of automated driving and the increasing adoption of “zero-gravity” seats, the crash safety of highly reclined occupants has become a critical issue. The current THOR dummy, designed for frontal impacts in the standard upright posture, exhibits limitations when directly applied to reclined seating configurations, including insufficient spinal flexion capability and excessive posterior pelvic rotation. In this study, the thoracolumbar spine kinematics of the THUMS human body model, reconstructed against post-mortem human subject (PMHS) tests, were analyzed. A two-segment linear fitting was employed to characterize a “dummy-like” spinal flexion response, yielding a virtual rotational hinge located near the thoracolumbar joint of the original THOR model. The characteristic rotation angle obtained from THUMS showed a strong linear correlation with the flexion moment of the T12–L1 vertebrae. Based on this relationship, the rotational joint of the THOR dummy was unlocked during impact and assigned a torsional stiffness of 600 Nm/rad. Additional modifications were implemented in the hip region to enhance model applicability. Comparative simulations demonstrated that the modified THOR model achieved closer agreement with PMHS responses than both the Hybrid III and the baseline open-source THOR models. In particular, the posterior pelvic tilt was reduced from approximately 20° in the baseline THOR to about 10° in the modified version. These results indicate that incorporating PMHS-based thoracolumbar flexion characteristics together with targeted hip modifications significantly improves the biofidelity of the THOR dummy for reclined-occupant crash scenarios, providing a solid foundation for future dummy development and safety assessment.
Guo, Wencheng, Kuang, Gaoyuan, Shen, Wenxuan, Tan, Puyuan, Zhou, Qing
Design and Simulation Analysis of an Integrated Honeycomb-Filled Front Bumper for a Special Vehicle2026-01-04754/7/2026
In frontal collisions of automobiles, the bumper beam at the front of the vehicle plays a crucial role in absorbing energy and protecting the vehicle body during a collision. To enhance the collision resistance of a specific type of special vehicle with a non-load-bearing body structure, this paper focuses on this type of vehicle and conducts a study on the design and collision performance of an integrated vehicle front bumper - anti-collision beam structure based on aluminum alloy additive manufacturing technology. A novel bumper structure is proposed, which integrates the front bumper and the front anti-collision beam of the vehicle and is integrally formed using aluminum alloy additive manufacturing technology. This integrated structure is directly connected to the vehicle frame. Firstly, based on the appearance of the special vehicle body and the form of the front anti-collision beam of traditional passenger vehicles, an integrated design of the vehicle front bumper- anti-collision beam structure is carried out and connected to the vehicle body. Subsequently, based on the previous bumper design, a honeycomb structure is introduced internally, and the introduced honeycomb structure is integrally formed with the front bumper. Finally, finite element simulation analysis of two types of frontal bumper collisions under the same collision conditions is conducted. The results show that the initial integrated front bumper can achieve basic anti-collision beam functions, while the front bumper with a honeycomb composite structure can improve the transmission path of collision force, ensure stable deformation, significantly enhance the energy absorbed during a collision, and increase the specific energy absorption, indicating that the integrated honeycomb-filled front bumper can effectively enhance the collision resistance of special vehicles.
王, Xufan, Yuan, Liu-Kai, Zhang, Tangyun, Wang, Tao, Zhang, Ming, Wang, Liangmo
Development of Automotive Hood Using Multi-Material Double Injection Molding – An Overview2026-01-04764/7/2026
This paper presents the multidisciplinary development of a hybrid automotive hood manufactured using double-shot injection molding with overmolded brackets. Conventional steel and aluminum hoods, while structurally reliable, pose challenges in terms of weight reduction, pedestrian head protection, and manufacturing cost. Composite and thermoplastic alternatives supported by computational analysis and advanced molding processes provide opportunities to address these challenges. Finite element analysis (FEA) was employed to evaluate torsional and bending stiffness, locking load, and crashworthiness, while pedestrian headform simulations following ECE R127 and EEVC WG17 guidelines were conducted to assess compliance with safety regulations. Adhesion and bonding strength of overmolded polymer–polymer interfaces were studied to validate manufacturing feasibility. Results confirm that hybrid hoods fabricated using multi-material double-shot molding can achieve weight reductions of up to 30% compared with steel, maintain structural stiffness equivalent to aluminum, meet head injury criterion (HIC) thresholds, and reduce assembly complexity by consolidating brackets and reinforcements into a single integrated structure.
Ganesan, Karthikeyan, Seok, Sang Ho, Jo, Hyoung Han
Multi-Physics Topology Optimization and Neural Network–Based Design of Experiments for Lightweight Automotive Cast Components2026-01-05104/7/2026
This paper presents a hybrid optimization framework that integrates Multi-Physics Topology Optimization (MPTO) with a Neural Network–surrogated Design of Experiments (NN-DOE) to enable lightweight structural design while satisfying crashworthiness, durability, and noise, vibration, and harshness (NVH) requirements under practical casting and packaging constraints. In the proposed MPTO formulation, crash and durability performances are incorporated through equivalent static compliance measures, while NVH performance is assessed using a frequency-domain dynamic stiffness metric, allowing consistent evaluation of trade-offs among competing design requirements. The framework is first demonstrated using a mass-produced passenger-car lower control arm (LCA) as a benchmark component. In this application, MPTO achieves weight reduction under multi-physics objectives by removing non-load-bearing material. Results show that single-discipline optimization produces unbalanced topologies, while balanced crash–durability–NVH consideration yields robust load paths. The study further demonstrates that crash and durability are dominated by static compliance–based response, whereas NVH performance is governed by frequency-dependent dynamic response over the relevant frequency range. The framework is then applied to a front engine mounting bracket of a newly developed heavy-duty truck. In this second application, a two-step strategy is employed in which MPTO first establishes the global load-carrying topology under manufacturing and packaging constraints, followed by NN-DOE–based local refinement to achieve stress attenuation at non-designable regions through global structural stiffness rebalancing, rather than direct geometric modification. Final verification confirms a steel-to-aluminum material transition achieving approximately 45% weight reduction and a substantial improvement in durability fatigue life, while maintaining required crash performance.
Kim, Hyosig, Senkowski, Andres, Gona, Kiran, Saroha, Lalit, Boraiah, Mahesh
Revisiting Rear Seat Safety: Field Evaluations of Relative Injury Risk Across Seating Positions and the Integration of Advanced Rear Seat Belt Systems2026-01-05614/7/2026
Despite advances in crash avoidance, occupant restraint systems remain crucial in protecting the motoring public. Following decades of improvement in occupant protection, including several supplemental restraint systems for front seat occupants, the safety of rear seat occupants has recently undergone scrutiny. Studies evaluating rear seat occupant injury risk via field crash data have reported reduced relative safety in rear seating positions and alluded to advanced rear seat restraints, such as pretensioners and load limiters, as potential solutions. While the pursuit of novel technologies has historically improved occupant outcomes, evaluation of new systems in both controlled laboratory environments and field crashes is necessary to understand potential consequences of widespread introduction. This study analyzed the prevalence of advanced seat belts (load limiters and pretensioners) in the rear seating positions in the U.S. fleet. Additionally, occupant injury risk was compared across vehicles equipped with conventional and advanced seat belts in the rear seat, as well as between rear and front seat occupants, using data from state crash databases. The proportion of vehicles equipped with advanced rear seat restraints has steadily increased over the past couple of decades, but, as of 2023, remained below 10% of registered vehicles on US roadways. Evaluation of police-reported field crash data indicated that lap-shoulder belted rear seat occupants sustained fatal or incapacitating injury at a lesser rate than front seat occupants. Rear seat occupants have historically been and remain well-protected. Current field data do not consistently demonstrate a statistically significant reduction in rear seat occupant injury or fatality risk attributable to advanced seat belts. However, the relatively low number of crashes involving serious injury or fatality for rear-seated occupants in vehicles equipped with these systems underscores the need for additional data to fully evaluate their effectiveness in real-world crashes.
Rapp van Roden, Elizabeth Ann, Miller, Bruce, Pearson, Joseph, Williamson, James, Brown, Thomas
Statistical Assessment of Pretensioner and Load Limiter Effects on the Large Omnidirectional Child ATD Response in Frontal Impacts2026-01-05504/7/2026
Enhancing child occupant protection requires a clear understanding of how seatbelt restraint parameters influence crash injury metrics. Real-world vehicles mostly include pretensioner and load limiter technologies to mitigate injuries, but rear seat restraints often do not include these. The FMVSS No. 213 test bench closely represents current restraint systems but does not involve such active vehicle restraint features. This study explores the response of the Large Omnidirectional Child ATD to evaluate potential injury mitigation under FMVSS No. 213 frontal sled test conditions. A simulation-based full factorial design was implemented in LS-DYNA to vary pretensioner retraction, retractor load-limiting thresholds, and webbing payout, with injury measures including head acceleration, head excursion, chest compression, and abdominal pressure twin sensors (APTS). Statistical evaluation using analysis of variance (ANOVA) and Tukey-Kramer post-hoc tests quantified main and interaction effects. Pretensioners consistently reduced head excursion and acceleration, while load limiters lowered chest compression but increased excursion, illustrating a performance trade-off. Webbing payout behavior showed strong coupling to load-limiting thresholds, revealing notable parameter interdependencies. These results demonstrate that integrating pretensioners and load limiters into child restraint systems could yield meaningful safety benefits but must be optimized holistically to balance competing injury metrics. The study provides both empirical insight and a statistical framework for evaluating advanced restraint configurations in pediatric occupant simulations.
Khattak, Mohid Muneeb, Bendig, Colleen, Louden, Allison, Noll, Scott
Terminology and Measurement Methodology for Determining Vehicle Overlap in Offset-Frontal CrashesJ3227_202604 (Current)4/1/2026
This SAE Information Report establishes procedures and terminology for measuring, calculating, and referencing the percent vehicle overlap for a case vehicle in real-world or staged end plane collisions where the end plane of the case vehicle is engaged at one of the two bumper corners but not both. This SAE Information Report may be applied to rear or front plane impacts.
Crash Data Collection and Analysis Standards Committee
Improve Safety Balance between Women and Men in Frontal Crashes through Parametric Human Modeling and Adaptive Design Optimization2025-22-00101/23/2026
Objective: Previous studies have reported disparity in injuries between male and female drivers in the risk of certain types of injuries in frontal crashes that may be due to a myriad of sex-related differences, including body size, shape, anatomy, or sitting posture. The objectives of this study are 1) to use mesh-morphing methods to generate a diverse set of human body models (HBMs) representing a wide range of body sizes and shapes for both sexes, 2) conduct population-based frontal crash simulations, and 3) explore adaptive restraint design strategies that may lead to enhanced safety for the whole population while mitigating potential differences in injury risks between male and female drivers Method: A total of 200 HBMs with a wide range of body sizes and shapes were generated by morphing the THUMS v4.1 midsize male model into geometries predicted by the statistical human geometry models. Ten male and ten female HBMs were selected for population-based simulations. An existing automated simulation framework was leveraged to rapidly set up crash simulations with the morphed HBMs and previously-validated driver compartment and restraint models. A total of 1,000 frontal crash simulations were performed under varied restraint designs and crash severities. A surrogate model was developed based on the simulation data using a Gaussian Process (GP) method. Two design optimization schemes were used to flexibly adjust design parameters based on subject variables to minimize population injury risks while minimizing differences in injury risk between male and female HBMs. Key Results: The simulations indicated that the joint injury probability (Pjoint) is more sensitive to the seatbelt and driver airbag variables at 35 mph, while the variability is greatly reduced at 25 mph for all design variables. The optimal adaptive design strategy from these models suggested a higher seat belt load limit, higher airbag inflation pressure, smaller airbag venting, and higher steering column force for occupants with higher body mass index (BMI). The adaptive design reduced the population Pjoint by 19.6%, 31.8% and 38.8% from the baseline design when Delta-V equals to 25, 30 and 35 mph, respectively. For high speed crashes (Delta-V = 35 mph), the proposed adaptive design reduced the average Pjoint differences between men and women from 24.02% to 2.84% compared to the baseline design. Surprisingly, a restraint strategy constrained to sex-based balance is able to maintain similar injury risks between male and female drivers. Major Conclusion: This study is the first to integrate finite element crash simulations with adaptive restraint design optimization to potentially reduce population injury risks and safety balance between male and female occupants. Gaussian process was shown to be an effective surrogate to FE simulations.
Sun, Wenbo, Hu, Jingwen, Lin, Yang-Shen, Boyle, Kyle, Reed, Matthew, Sun, Zhaonan, Hallman, Jason
Investigating Pelvic Locking and Torso Kinematics Using Human Body Models in Frontal Impact Scenarios2026-26-00021/16/2026
Occupant Safety systems are usually developed using anthropomorphic test devices (ATDs), such as the Hybrid III, THOR-50M, ES-2, and WorldSID. However, in compliance with NCAP and regulatory guidelines, these ATDs are designed for specific crash scenarios, typically frontal and side impacts involving upright occupants. As vehicles evolve (e.g., autonomous layouts, diverse occupant populations), ATDs are proving increasingly inadequate for capturing real-world injury mechanisms. This has led to the adoption of computational Human Body Models (HBMs), such as the Global Human Body Models Consortium (GHBMC) and Total Human Model for Safety (THUMS), which offer superior anatomical fidelity, variable anthropometry, active muscle behaviour modelling, and improved postural flexibility. HBMs can predict internal injuries that ATDs cannot, making them valuable tools for future vehicle safety development. This study uses a sled CAE simulation environment to analyze the kinematics of the HBMs model in a frontal crash scenario. The methodology includes the initial correlation of Hybrid III CAE simulation results with physical sled test data, followed by a comparative analysis with GHBMC M50-O v6-2 based simulations. A significant difference was observed in pelvic forward displacement between the Hybrid III and GHBMC M50-O v6-2. The difference in interaction originates from the difference in the construction of the pelvis between the Hybrid III and GHBMC. In the GHBMC, reduced displacement occurs because the pelvis locks in the seat. This interaction is absent in ATDs, resulting in increased torso rotation and a potential rise in upper extremity injury risk for HBMs. The study examines the various reasons for pelvic locking and increased upper body rotation. These evaluations aim to raise the negative consequences of pelvic locking on upper extremity injuries. The probable solutions that can reduce pelvis locking while preserving occupant stability is also discussed. The study highlights the significance of HBMs in understanding occupant interactions and supports their use in the development of next-generation restraint systems.
Raj, Pavan, Rao, Guruprakash, Pendurthi, Chaitanya Sagar, Nehe, Vaibhav, Chavan, Avinash
Optimization of Frontal Impact Force Scheme to Accelerate the Target Setting Process for Development of Front-End Structures in Vehicles2026-26-00011/16/2026
A passenger vehicle's front-end structure's structural integrity and crashworthiness are crucial to ensure compliance with various frontal impact safety standards (such as those set by Euro NCAP & IIHS). For a new front-end architecture, design targets must be defined at a component level for crush cans, longitudinal, bumper beam, subframe, suspension tower and backup structure. The traditional process of defining these targets involves multiple sensitivity studies in CAE. This paper explores the implementation of Physics-Informed Neural Networks (PINNs) in component-level target setting. PINNs integrate the governing equations into neural network training, enabling data-driven models to adhere to fundamental mechanical principles. The underlying physics in our model is based upon a force scheme of a full-frontal impact. A force scheme is a one-dimensional representation of the front-end structure components that simplifies a crash event's complex physics. It uses the dimensional and positional parameters of the components, along with their force-displacement curves, to estimate the vehicle's crash pulse. In this work, we have implemented PINNs to generate an optimized force scheme using the historical CAE test data. Using this approach promises to cut short the time and cost that goes into the conventional process of target setting.
Gupta, Ishan, Bhatnagar, Abhinav, Kumar, Ayush
Chest Deflection Mapping between HBM-Connect® 50M and Virtual ATD Models2026-26-00101/16/2026
Human Body Models (HBMs) are increasingly recognized by consumer protection agencies as essential tools for evaluating vehicle safety, complementing the use of traditional Anthropomorphic Test Devices (ATDs). However, HBMs are new for product development and pose challenges in connecting them with the ATDs. These challenges can be overcome if a link is established for the injury metrics between HBMs and ATDs. The study aims to develop a chest deflection mapping function between the HBM Connect® 50M and three ATD models: Hybrid III 50M, THOR-50M and World SID 50M for thoracic assessment in impact scenarios. Several frontal and lateral thorax loading scenarios were selected from the HBM4VT qualification catalogue (Euro NCAP technical bulletin CP 550), including hub impacts and table-top seatbelt loading tests. Matched-pair LS-DYNA simulations were conducted with HBM Connect® 50M and the ATD models recording peak chest deflections for developing the mapping function. In the HBM Connect® 50M model, deflection outputs were defined- analogous to the four IR-TRACCs in THOR-50M, one for sternum potentiometer in Hybrid III 50M and IR-TRACCs analogous to World SID. Three linear regression models were developed: one mapping chest deflections between HBM Connect® 50M and THOR-50M, second between HBM Connect® 50M and Hybrid III 50M and the third between HBM Connect® 50M and World SID 50M. The mapping suggests that a 30mm chest deflection in THOR-50M, Hybrid III 50M and World SID 50M corresponds to approximately 47mm, 58mm and 55mm, in HBM Connect® 50M suggesting that HBMs are softer and more compliant than ATDs for the torso region. Data points were selected to ensure a coefficient of determination (R2>0.9. Future work will include additional sled cases to further validate and improve these mappings for various impact load case applications. This study establishes chest deflection mapping functions to facilitate the interpretation of HBM Connect® 50M outputs using established ATD-based chest deflection metrics. A strong correlation is observed with THOR-50M, and a moderate correlation is observed with Hybrid III 50M and World SID 50M.
Velmurugan, Gopinath, Kumar, Devendra, R, Udhaya Kumar, Kulavi, Pradeep, Soni, Anurag, Tejero de la Piedra, Ricardo, Fu, Stephen, Long, Teng, Arora, Tushar, Jagadish, Renuka, Shah, Chirag
An Innovative Collision Sensing Architecture for Robust Functionality of Safety Restraint Systems in Different Challenging Real World Accident Scenarios2026-26-00171/16/2026
In emerging markets, especially in India and other similar countries, the growing traffic density on the roads leads to different types of accidents, including frontal head-on collisions, rear-end collisions, side-impact collisions, collisions with fixed objects such as electric poles, trees, road guard rails, road dividers, and accidents involving pedestrians, cyclists, and two-wheelers. These accidents could be due to over speeding, distracted driving, violation of traffic rules, and inadequate road infrastructure etc. Providing the necessary safety restraint systems (Airbags and Seat belts) in vehicles and ensuring their robust functionality in different real-world accident scenarios will be challenging for vehicle manufacturers. It is high time to redefine the traditional collision-sensing architecture strategies with a logical approach based on a thorough study of available accident data statistics, types of objects, and scenarios leading to severe accidents. Among these, rear-end collisions (such as car-to-truck under-ride), side collisions, and head-on collision accident cases are increasing day by day. Ineffective sensing of collision signals and inadequate functionality of the safety restraint system can lead to severe injuries or fatalities. It is imperative to improvise the collision sensing system architecture and place the crash sensors inventively at optimal locations in the vehicle with an innovative approach for the early detection of collision signals and for the robust functionality of the safety restraint systems to mitigate occupant injuries and reduce fatalities to the maximum extent. This technical paper describes the thought process and methodology used to improve collision sensing techniques for the robust functionality of safety restraint systems in rear-end collisions (mainly car-to-truck underride), side impact collisions, head-on collisions, and undercarriage/underbody scraping scenarios (especially for EV battery packs). This innovative collision-sensing architecture system can be introduced in vehicles to cater to the needs of robust functionality of safety restraint systems (Airbags and Seat belts) in different real-world accident scenarios to protect vehicle users with improvisation in the existing situations while ensuring fuel cut-off in the case of ICE and high-voltage cut-off in the case of EV vehicles.
KOVALAM, SUNIL KUMAR
Adaptive Restraints for Equitable Protection2026-26-00151/16/2026
Real-world crashes involve diverse occupants, but traditional restraint systems are designed for a limited range of body types considering the applicable regulations and protocols. While conventional restraints are effective for homogeneous occupant profiles, these systems often underperform in real-world scenarios with diverse demographics, including variations in age, gender, and body morphology. This study addresses this critical gap by evaluating adaptive restraint systems aligned with the forthcoming EURO NCAP 2026 protocols, which emphasize real-world crash diversity and occupant type. Through digital studies of frontal impact scenarios, we analyze biomechanical responses using adaptive restraints across varied occupant demographics, focusing on head and chest injury (e.g., Chest Compression Criterion [CC]). This study used a Design of Experiments (DOE) approach to optimize occupant protection by timing the actuating of these adaptive systems. The results indicate that activating adaptive seatbelts and airbags before reaching peak chest and pelvis accelerations can help reduce injuries. The study suggests a rule-based framework for adaptive restraints, demonstrating that injury optimization correlates strongly with time control of restraint parameters. These insights advance the development of occupant-centric safety systems, offering scalable solutions for emerging regulatory standards and enhancing protection for underrepresented demographics in vehicular safety engineering.
satija, Anshul, Suryawanshi, Yuvraj, Chavan, Avinash, Rao, Guruprakash
Pre-Crash Characteristics of Motorized Two-Wheeler Crashes on Indian Roads2026-26-00341/16/2026
India has emerged as the world’s largest market for motorized two-wheelers (M2Ws) in 2024, reflecting their deep integration into the country’s transportation fabric. However, M2Ws are also a highly vulnerable road user category as according to the Ministry of Road Transport and Highways (MoRTH), the fatality share of M2W riders rose alarmingly from 27% in 2011 to 44% in 2022, underlining the urgency of understanding the circumstances that lead to such crashes. This study aims to investigate the pre-crash behavior and crash-phase characteristics of M2Ws using data from the Road Accident Sampling System – India (RASSI), the country’s only in-depth crash investigation database. The analysis covers 3,632 M2Ws involved in 3,307 crash samples from 2011 to 2022, representing approximately 5 million M2Ws nationally. Key variables examined include crash configuration, collision partner, road type, pre-event movement, travel speed, and human contributing factors. The study finds that straight-line travel, overtaking, and negotiating curves are among the most common pre-event movements preceding fatal crashes. Head-on and object-related collisions as well as crashes involving heavy vehicles show higher fatality rates. Human behaviors such as abrupt turns, over-speeding, unsafe overtaking, and riding under the influence of alcohol are major contributors to crash causation. The findings emphasize the need for targeted enforcement, rider training, and improved road infrastructure to reduce the burden of two-wheeler-related fatalities in India.
Govardhan, Rohan, Padmanaban, Jeya, Jethwa, Vaishnav
Safer Trucks for India: Smart Tech Fusion2026-26-00311/16/2026
Commercial vehicle sector (especially trucks) has a major role in economic growth of a nation. With improving infrastructure, increasing number of trucks on roads, accidents are also increasing. As per RASSI (Road Accident Sampling System India) FY2016-23 database, commercial vehicles are involved in 42% of total accidents on Indian roads. Involvement of trucks (N2 & N3) is over 25% of total accidents. Amongst all accident scenarios of N2 &N3, frontal impacts are the most frequent (26%) and causing severe occupant injuries. Today, truck safety development for frontal impact is based on passive safety regulations (viz. front pendulum – AIS029) and basic safety features like seatbelts. In any truck accident, it is challenging rather impossible to manage comprehensive safety only with passive safety systems due to size and weight. Accident prevention becomes imperative in truck safety development due to extremely high energy involved in front impact scenarios. The paper presents a unique safety development approach (for frontal impact safety development for N2 and N3 trucks) which enables smart synthesis of active and passive safety systems to comprehensively address real world safety. Four major areas are identified for truck safety development viz. structural crashworthiness, compatibility, occupant safety and ADAS (Advanced Driver Assistance System). The innovation lies in smart mix of these areas during product safety development. The study presents the safety development of light commercial vehicle (truck) with this approach. Structural crashworthiness & occupant safety are developed with extensive number of CAE simulations. Design is physically validated with frontal impact test. In addition, extensive mileage accumulation is generated across Indian roads to validate ADAS system performance.
Joshi, Kedar Shrikant, Gadekar, Ganesh, Date, Atul, Koralla, Sivaprasad
Multi-Material Front Structures: A Pathway to Safer and More Sustainable Vehicle Design2026-26-04561/16/2026
Frontal crash structures play a vital role in occupant safety, but traditional designs often involve a trade-off between structural strength and weight efficiency. In the pursuit of safer and more sustainable mobility, this study explores a physics-based methodology that leverages the principle of dynamic equilibrium to guide the integration of dissimilar materials in front-end vehicle structures. Specifically, examined a novel configuration wherein aluminum High-pressure die cast (single HPDC part) is introduced which covers swan neck region as well as the base of the front longitudinal member, while retaining steel in the frontal crush zone. This arrangement aims to redistribute crash loads and control deformation mechanisms, enabling improved energy absorption without compromising structural integrity. To evaluate the proposed strategy, a series of detailed finite element simulations were conducted using LS-DYNA, a widely adopted tool for vehicle crash analysis. The results reveal that the dynamic equilibrium approach offers a rational and most efficient framework for material allocation, allowing for the optimization of crash performance metrics while simultaneously achieving weight reduction. Compared to conventional all-steel or all-aluminum designs, the hybrid structure demonstrate efficient, improved crashworthiness, with measurable mass savings. By grounding material decisions in mechanical principles rather than empirical iteration, this research presents a scalable methodology applicable to a wide-range of vehicle platforms. The outcomes offer a compelling case for the adoption of multi-material architectures as a pathway toward enhanced crash safety and reduced environmental impact.
Revanth, Goshika, Bhagat, Milind, Joshi, Vikas, Mankhair, Abhijit, Sudarshan, B.Sudarshan, Kollipara, Jahanavi
Design and Validation of a Collapsible Brake Pedal System for Lower-Leg Protection in Frontal Impacts2026-26-05001/16/2026
Indian passenger car accident data indicates that approximately 44% of crashes are frontal impacts (Refer fig 1). Among the injuries sustained in these crashes, lower leg injuries are notably critical, contributing to nearly 25% of driver occupant injuries (Refer fig 2). To evaluate such injuries, the Bharat New Car Assessment Program (BNCAP) includes lower leg injury metrics as part of the Frontal Offset Deformable Barrier (ODB64) test. While the overall injury performance is assessed at the vehicle level, BNCAP also monitors vehicle interior intrusions—particularly pedal intrusions—as key contributors to lower limb injury severity. A major challenge in frontal crashes is the intrusion of the vehicle's front-end structure into the occupant compartment. Rigid components, particularly the brake pedal assembly, can be displaced rearward during a crash, significantly increasing the risk of lower leg injuries. Therefore, minimizing pedal intrusions into the driver foot-well is critical for enhancing lower leg protection. As part of an innovative safety initiative, Tata Motors has developed a collapsible brake pedal mechanism designed to mitigate lower leg injuries during frontal crashes. This patented system incorporates a series of levers and linkages that disengage upon impact, allowing the brake pedal to collapse and thereby reducing the risk of intrusion-related injuries to the driver lower legs. The mechanism is engineered to be robust, ensuring that normal braking performance and pedal operation remain unaffected during everyday vehicle use, while providing effective injury mitigation in crash scenarios.
Shetti, Rahul R., Kudale, Shailesh, Naik, Nagaraj, Bisen, Badal, Kotak, Vijay, Dudhewar, Swapnil, Bhagat, Amit, Durgaprasad, HNV
Pulse and Polynomial Functions to Predict Vehicle Acceleration Using Event Data Recorder Delta-V in Frontal and Rear-End Collisions2025-01-50466/27/2025
The lack of recorded acceleration and limited Delta-V (ΔV) resolution in many vehicle event data recorders necessitates the development of a method to predict continuous vehicle acceleration based on ΔV responses. This study developed a method of obtaining continuous acceleration by regressing pulse functions (triangular, half-sine, haversine) and polynomial functions (orders 3–6) to a ΔV curve and deriving the corresponding acceleration–time curve. The effectiveness of this method was demonstrated using real-world ΔV response data from front and rear-end collisions. Comparisons were performed between peak and average acceleration values from each front and rear-end crash pulse. Results indicated that a triangular pulse function predicted similar peak acceleration values to the vehicle’s actual acceleration in frontal and rear-end impacts. Average acceleration in frontal impacts was best predicted utilizing a fifth-order polynomial, while a sixth-order polynomial demonstrated the best predictive ability for rear-end impacts. Obtaining equations for vehicle ΔV and acceleration is crucial in assessing impact severity due to the vehicle’s dynamic response.
Westrom, Clyde, Adanty, Kevin, Shimada, Sean D.
A Low-Entry Bus Body Structure Performance under the Conditions of the New Car Assessment Program Frontal Crash Tests09-13-02-00074/9/2025
The New Car Assessment Program (e.g., US NCAP and EuroNCAP) frontal crash tests are an essential part of vehicle safety evaluations, which are mandatory for the certification of civil means of transport prior to normal road exploitation. The presented research is focused on the behavior of a tubular low-entry bus frame during a frontal impact test at speeds of 32 and 56 km/h, perpendicular to a rigid wall surface. The deformation zones in the bus front and roof parts were estimated using Ansys LS-DYNA and considered such factors as the additional mass (1630 kg) of electric batteries following the replacement of a diesel engine with an electric one. This caused stabilization of the electric bus body along the transverse axis, with deviations decreased by 19.9%. Speed drop from 56 to 32 km/h showed a reduction of the front window sill deformations from 172 to 132 mm, and provided a twofold margin (159.4 m/s2) according to the 30g ThAC criterion of R80. This leads to the conclusion about the recommendation to reduce the regulatory NCAP speed for city buses to ensure a sufficient safety margin, especially considering the city speed limit of 40–50 km/h. The novelty consists in the application of the NCAP regulations, which is not typical for buses, with the formation of conclusions about the higher danger for passengers compared to UNECE R29 due to the much deeper penetration of plastic deformations into the bus body (up to the rear axle). The obtained results can influence accident prevention strategies and the revision of the city bus certification approaches and regulations.
Holenko, Kostyantyn, Dykha, Aleksandr, Koda, Eugeniusz, Kernytskyy, Ivan, Royko, Yuriy, Horbay, Orest, Berezovetska, Oksana, Rys, Vasyl, Humeniuk, Ruslan, Berezovetskyi, Serhii, Chalecki, Marek
The Influence of out-of-Position Displacement during Emergency Braking on Occupant Whiplash Injury in Subsequent Rear-End Collisions2025-01-87204/1/2025
In the pre-crash emergency braking scenario, the occupant inside the vehicle will move forward due to inertia, deviating from the standard upright seating position for which conventional restraint systems are designed. Previous studies have mainly focused on the influence of out-of-position (OOP) displacement on occupant injuries in frontal collisions, and provided solutions such as active pretensioning seatbelts (APS). But little attention has been paid to the influence of OOP on whiplash injury during a subsequent rear-end collision. To investigate the forward OOP impact on whiplash injuries and the effectiveness of APS in this accident scenario, a vehicle interior model with an active human body model (AHBM) was setup in the MADYMO simulation platform. Different braking strengths (0.8g and 1.1g), APS triggering times (from 0.2s before to 0.2s after the braking initiation) and pretensioning forces (from 100N to 600N) were input to the simulation matrix. The occupant’s forward OOP displacement prior to the rear-end collision and the corresponding whiplash injury metrics including neck shear force, tension force, and neck injury criteria (NIC) in the subsequent moderate rear-end collision were recorded. The simulation results indicated that: (1) The occupant’s whiplash injury metrics were positively linearly correlated with the pre-crash forward OOP displacement. (2) The APS could not fully eliminate the forward displacement brought by neck flexion, causing whiplash injury metrics to exceed the capping limits (upper bounds) defined in current vehicle safety assessment protocols like Euro-NCAP.
Fei, Jing, Qiu, Hang, Wang, Peifeng, Liu, Yu, Cheng, James Chih, Zhou, Qing, Tan, Puyuan
Analyzing EV Battery Package Responses during Side Pole Impacts with Multiple Speeds and Locations2025-01-87304/1/2025
Electric vehicles (EVs) have experienced significant growth, and the battery safety of EVs has drawn increased attention. However, the mechanical responses of battery during crashes have rarely been studied. Hence, the objective of this study was to understand EV battery package mechanics during side-pole crashes at different impact locations and speeds beyond regulated side-pole test with one specific speed and one location. An EV finite element (FE) model with a battery package was used. Side-pole impact simulations were conducted at four impact locations, including the baseline impact location according to side-pole impact regulation, plus three positions by moving the rigid pole 400 mm toward the back of the EV and moving the pole 400 and 800 mm toward the front of the EV. In addition, the impact velocities at 32, 50, and 80 km/h were simulated. Based on simulations, the peak relative displacement, the maximum change in gap between batteries, the maximum change in gap between the battery and the inner wall, and battery housing stress were analyzed. Lastly, frontal impacts at both 50 and 80 km/h were simulated for comparison. Results demonstrated that at 50 km/h side-pole impact, the battery was left intact. However, at 80 km/h, a slight intrusion of deformed battery housing into the battery was observed. Impact locations played a critical role, as the impacts near the center of the battery package induced the largest deformations. In comparison, during all frontal impacts, the battery was not affected. Overall, side-pole impacts at higher velocities beyond regulated speed could be further investigated for continuously enhancing EV safety.
Chen, Jian, Bian, Kewei, Mao, Haojie
The Influence of Reclined Seatback Angles on Occupant Injury Risks in Frontal Impacts2025-01-87324/1/2025
The reclined seatbacks will be increasingly used with the advanced technologies of the intelligent automobile. The occupant collision protection must rise to the challenge facing to the new impact scenarios. It is necessary to understand the injury mechanisms of the reclined occupants in order to design the resistant system and testing protection regulations. In this study, simulation tests were conducted for the Frontal Full Width Impact (FRB) and the Mobile Progressive Deformable Barrier Frontal Impact (MPDB) as specified in the China New Car Assessment Programme (C-NCAP, 2021 version). The simulation used the biomechanical model of the 5th female occupant exhibiting the detailed anatomical structures and a seat model with large-angle seatback. The occupant injury risks and mechanisms with 25°, 45° and 60° seating postures were investigated by analyzing the kinematic and biomechanical parameters, and the influence of the seatback angle on occupant injury was discussed. The results indicate that reclined seatback significantly affects the kinematic responses of the head and neck, with head and neck injuries acting as primary contributors to C-NCAP score reductions. Seatback angle and collision type are key factors influencing the risk of visceral and lumbar spine injuries. In FRB impact condition, the risk of visceral injury reduces by 18% and 17% with the increasing seatback angle, respectively, while the risk of lumbar spine injury decreases by 1% and increases by 38%. In MPDB impact condition, the risk of visceral injury reduces by 28% and 32% with increasing seatback angle, and increases the risk of lumbar spine injury by 51% and 32%, respectively. In conclusion, the head, neck, and visceral organs are common injury regions for occupants in reclined seatbacks, and the collision types influence the injury mechanisms. Mitigating the range of head and neck motion and the compressive forces on visceral organs are critical for protecting reclined posture occupants. These findings from this study could contribute significantly to the development of regulations and restraint systems for reclined occupant protection.
Wang, Yanxin, Pan, Ruyang, Lin, Yuyang, Liu, Yutao, He, Lijuan, Wang, Zhenqiang, zhu, he, Liu, Chong, Li, Kun, Lv, Wenle
Predicting Head Injury Criterion in Real-World Frontal Impacts2025-01-87094/1/2025
Research on modeling head injury metrics and head acceleration waveforms from real-world collisions has been limited compared to vehicle crash pulses. Prior studies have used rectangular, triangular, polynomial, half-sine, and haversine pulse functions to model vehicle crash pulses and have employed more complex approximations for head injury metrics. This study aimed to develop a method to predict 15 ms Head Injury Criterion (HIC15) in frontal passenger vehicle impacts using these simple pulse functions, where only occupant peak head acceleration and head impact duration are known. Vehicle crash tests from the New Car Assessment Program (NCAP) were selected for frontal impacts that included driver occupants. Head acceleration and shoulder belt load channels of Hybrid III 50th percentile male anthropomorphic test devices were collected and separated for training a set of ratios and testing their performance. Rectangular, triangular, quadratic, half-sine, and haversine pulse functions were modeled using peak head acceleration and the duration of significant head acceleration from each ‘training’ NCAP crash test. Duration ratios were values calculated to scale each pulse function to predict the same HIC15 as the driver’s experimental acceleration-time curve. Duration ratios were evaluated on each ‘testing’ NCAP crash test by comparing the HIC15 predicted by each scaled pulse function against the driver’s HIC15. All five pulse functions generated from the model ‘training’ NCAP tests had significantly different duration ratios. There were no significant differences in predicted HIC15 to the driver’s HIC15 from the model ‘testing’ NCAP tests for all pulse functions. Findings indicate that applying the presented duration ratios to the five pulse functions can effectively predict HIC15 in frontal crashes similar to NCAP tests, making them useful tools when only peak head acceleration and head impact duration are known. This work will help biomechanical safety experts evaluate head injury risk when real-time occupant kinematics are not available.
Westrom, Clyde, Tanczos, Rachel, Adanty, Kevin, Shimada, Sean
A Study on Affections of Active Neck Muscle Force on Neck Injury Responses in Frontal Impact with Automatic Emergency Braking Conditions2025-01-87424/1/2025
Neck injury is one of the most common injuries in traffic accidents, and its severity is closely related to the posture of the occupant at the time of impact. In the current era of smart vehicle, the triggered AEB and the occupant's active muscle force will cause the head and neck to be out of position which has significant affections on the occurrence and severity of neck injury responses. Therefore, it is very important to study the influences of active muscle force on neck injury responses in in frontal impact with Automatic Emergency Braking conditions. Based on the geometric characteristics of human neck muscles in the Zygote Body database, the reasonable neck muscle physical parameters were obtained firstly. Then a neck finite element model (FEM) with active muscles was developed and verified its biofidelity under various impact conditions, such as frontal, side and rear-end impacts. Finally, using the neck FEM with or without active muscle force, a comparative study was conducted on the kinematics and injury responses of the neck in the frontal impact with AEB condition. The research findings indicate that the activation of cervical active muscle forces effectively reduces the displacement of the head's center of gravity prior to the collision and significantly decreases the relative angular displacements between cervical vertebrae during the collision. These dynamic response changes mitigate the injury severity of cervical vertebrae, ligaments, and intervertebral discs, thereby enhancing the biomechanical tolerance of the cervical structure to mechanical loads.
Junpeng, Xu, Gan, Qiuyu, Jiang, Binhui, Zhu, Feng
Literature Review and Framework for Identifying Seat Belt Misuse and Misrouting in Frontal Collisions2025-01-87214/1/2025
The effect of seat belt misuse and/or misrouting is important to consider because it can influence occupant kinematics, reduce restraint effectiveness, and increase injury risk. As new seatbelt technologies are introduced, it is important to understand the prevalence of seatbelt misuse. This type of information is scarce due to limitations in available field data coding, such as in NASS-CDS and FARS. One explanation may be partially due to assessment complexity in identifying misuse and/or misrouting. An objective of this study was to first identify types of lap-shoulder belt misuse/misrouting and associated injury patterns from a literature review. Nine belt misuse/misrouting scenarios were identified including shoulder belt only, lap belt only, or shoulder belt under the arm, for example, while belt misrouting included lap belt on the abdomen, shoulder belt above the breasts, or shoulder belt on the neck. Next, the literature review identified various methods used to assess misuse/misrouting including testimonies and physical evidence on the occupant (i.e., belt marks/injury pattern) and on the vehicle interior and/or restraint system (i.e., loading marks). The literature review also highlighted the scarcity of test data on this topic, which may be beneficial to help guide technologies used to address and detect such scenarios. A surrogate study with a female volunteer was conducted for each of the nine belt misuse/misrouting scenarios identified from the literature review. The webbing lengths and angles at the hardware were measured. The results provide a first step in documenting evidence that could be part of a crash investigation. Additional studies with various size occupants are suggested, in conjunction with physical and/or mathematical simulation tests. Based on the literature review, a comprehensive and integrated framework to determine belt misuse/misrouting was summarized. The framework is based on information from police and accident vehicle investigation, and medical and radiology records. It also highlighted the need to measure webbing lengths and seat belt hardware angles that can be used in conjunction with surrogate studies and dynamic tests. Technologies such as video footage from in-vehicle cameras have the potential to provide additional data.
Gu, Emily, Parenteau, Chantal
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