Browse Topic: Safety belts

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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.
Dynamic and Static Optimization Design of Car-seat Structure2026-99-16147/24/2026
A car seat is one of the most critical components of passive safety. On the basis of the safety of car seats, this paper focuses on optimizing the design of the seat frame and achieving a lightweight design under various dynamic and static loading conditions. The optimization results are verified through physical experiments, which demonstrate the correctness and feasibility of the proposed design method. These experiments also provide research ideas for the optimization design of the seat structure and a certain reference value for the engineering application of the seat.
Shao, Youlin, Ni, Weiyu, Chen, Daojiong
Crashworthiness of WC19 Wheelchairs in Vertical Dynamic Aircraft Seating Tests09-14-02-00047/9/2026
Currently, people who use wheelchairs are not permitted to use their own wheelchairs as seats on commercial aircraft. To advance equitable aircraft travel for these passengers, we need to determine whether wheelchairs would be safe seating for their occupants and not pose a safety hazard for other passengers in case of emergency landing. We hypothesized that wheelchairs meeting the voluntary standards for vehicle crashworthiness (Rehabilitation Engineering Society of North America [RESNA] Section 19 Wheelchairs Used as Seats in Motor Vehicles [WC19]) would be able to pass the Federal Aviation Administration (FAA) vertical crashworthiness standards for aircraft seating. Wheelchairs were secured using surrogate 4-point strap tiedowns using the geometry specified by WC19. The FAA Hybrid III anthropomorphic test device (FH3 ATD) was restrained by both the wheelchair-attached lap belt and a vehicle-mounted lap belt identified as necessary to pass FAA dynamic horizontal test requirements. For the dynamic vertical testing with the wheelchairs oriented 60 degrees relative to horizontal, modeling demonstrated the suitability of using the trapezoidal pulse achieved with the UMTRI sled produced rather than the typical triangular shaped FAA pulse. Of the five manual and three power wheelchairs tested, four had broken components that would not impede emergency exit, four did not have visible damage, and the FH3 remained within the seat in all tests. The three power wheelchairs did not meet lumbar compression requirements. Based on these results, it may be feasible for people to use their own WC19-compliant wheelchairs on aircraft when secured to the aircraft with 4-point strap tiedown systems, supplemented by an occupant lap belt anchored to the aircraft, notwithstanding the lumbar force requirement.
Manary, Miriam A., Orton, Nichole Ritchie, Vallier, Tyler, Boyle, Kyle J., Klinich, Kathleen DeSantis
Assessing the Influence of Reclined Vehicle Seatback Configurations with and without a Belt-Positioning Booster on Child Posture via Pressure Mapping09-14-01-00045/4/2026
Objective: This study sought to implement pressure mapping methodology to assess variation in children’s center of force positions in reclined vehicle scenarios. Methods: Thirty-four children between 4 and 12 y (8.1 ± 2.0 y) were statically evaluated on a vehicle seat across two seating conditions (with and without a backless booster) and three seatback recline conditions (25°, 45°, and 60°). Center of force was recorded using pressure sensors attached to the seating surface. Average center of force fore/aft positions were calculated and transformed into the vehicle coordinate system using 3D coordinate measurements. Descriptive statistics and repeated measures ANOVA were used to assess variation in center of force position across seating and recline conditions, with subject included as a random effect. Results: Center of force fore/aft position varied (p < 0.05) with recline condition, seating condition, and the recline/seating condition interaction term. On the booster, the average center of force position became more aft in the 45° (131.1 ± 17.5 mm) and 60° (125.5 ± 16.7 mm) conditions compared to 25° (148.7 ± 17.4 mm). Without the booster, the center of force also became more aft in the 45° (197.7 ± 31.1 mm) condition compared to the 25° condition (204.6 ± 29.1 mm), but the position in the 60° (206.1 ± 31.8 mm) condition was similar. As children assumed more reclined postures, the center of force became more aft, except for the no-booster 60° condition. Discussion: Changes in center of force followed the same trends observed in the pelvis and lower extremity position (became more aft) with increasing seatback recline on the booster and smaller changes observed on the no-booster condition. Future work should investigate additional vehicle/booster geometries and longer seating durations. The changes in center of force observed with seatback recline emphasize the importance of understanding how real children modify their posture over time to different vehicle environments as posture directly influences belt fit, occupant–restraint interaction, and injury risk. Center of force data can inform the positioning of child surrogates in future dynamic evaluations of reclined configurations.
Baker, Gretchen H., Connell, Rosalie R., Graci, Valentina, Mansfield, Julie A.
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
Securing Child Restraint Systems in Motor VehiclesJ1819_202604 (Current)4/13/2026
The scope of this SAE Recommended Practice is to promote compatibility between child restraint systems and vehicle seats and seat belts. Design guidelines are provided to vehicle manufacturers for certain characteristics of seats and seat belts and to child restraint system (CRS) manufacturers for corresponding CRS features so that each can be made more compatible with the other. The CRS accommodation fixture (see Figure 1) is used to represent a CRS to the designers of both the vehicle interior and the CRS for evaluation of each product for compatibility with the other. The features of the accommodation fixture are described as each is used.
Children's Restraint Systems Committee
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
Potential Regulatory Approaches for Occupant Safety in Automated Vehicles with Unique Seating Configurations – Part 2: Interior Safety Sensing and Messaging Proposals2026-01-05764/7/2026
This paper contains Part 2 of a two-part paper series proposing potential regulatory approaches for occupant safety in Automated / Autonomous Vehicles (AVs) with unique seating configurations (stagecoach and campfire seating). Part 2 focuses on interior safety sensing, associated messaging, and ride control approaches both prior to and during a ride. Assessments are also proposed after significant vehicle braking and crash events. The proposed conditions are to be assessed in a static vehicle environment with humans segmented by occupant size and an infant dummy. On the vehicle seat and on the vehicle floor occupant detection conditions are proposed along with restraint usage detection conditions for vehicle seat belt usage, Child Restraint Seat (CRS) usage, CRS seat belt usage, and Lower Anchors and Tethers for Children (LATCH) system usage. These conditions may be detected by sensors / computer algorithms and human monitoring and thus are technology agnostic. The topics of animal detection and cargo detection are also discussed. Part 1 of this paper series (SAE paper 2026-01-0578) proposed using interior safety sensing as an alternative / a replacement for the National Highway Traffic Safety Administration (NHTSA) Federal Motor Vehicle Safety Standard 208 (FMVSS-208) Occupant Crash Protection unbelted in-position occupant compliance conditions. This paper proposes conditions involving occupant and seat belt restraint usage detection. This evaluation approach strives to prevent unbelted occupants and is an improvement over restraint countermeasures for unbelted occupants. This paper also discusses and proposes visual and audible safety messaging for prior to the ride occupant education and for occupant and restraint usage detection outcomes. Vehicle level ride control actions are suggested such as preventing a ride when improperly restrained occupants are detected. These approaches can be used in industry-wide regulatory next step contemplation for unique interior seating arrangement AVs. When adopted, these approaches would likely reside in an expanded version of FMVSS-208.
Thomas, Scott
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
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
Leveraging Machine Learning for Occupant Body Size Estimation via B-Pillar Seatbelt Systems2026-01-05594/7/2026
Occupant body size in vehicles varies significantly, encompassing differences in height, mass, and overall body composition. Adaptive restraint systems, featuring adjustable parameters such as belt load limiters, steering column load limiters and stroke, seat pan stiffness, and airbag pressure, can offer more equitable protection tailored to individual body sizes. In this study, a test rig modeled after the Volvo XC90 (2016) was used to collect data from 46 participants who were dressed in typical summer clothing and seated upright, without slouching or leaning sideways. Stepwise adjustments of the seat pan and seatback were performed. The collected measurements include seat pan movements (front-back and up-down), seatback recline, and key seatbelt-related parameters, such as belt payout length, D-ring angle, lap belt length, and buckle tension. The collected data was then used to train machine learning models to predict individual occupant characteristics: standing height, mass, and seated height. This study shows the challenges and opportunities for occupant body size estimation from seatbelt and seat location inputs. The prediction’s root mean square error across validation dataset was as follows: standing height 8.76cm, mass 11.33kg, and seated height 5.61cm. The prediction of mass fulfilled the defined criterion, while the prediction accuracy for standing height and seated height require further improvement. Our analysis reveals that a key improvement could be achieved by implementing an upgraded lap belt position sensor, given that lap belt length was identified as a dominant feature across models. Furthermore, the analysis suggests that D-ring angle, buckle tension, and seatback recline can be excluded from the input feature set.
Wang, Da, Ahmed, Jawwad, Rowe, Mike, Brase, Dan
Evaluating the Effects of Improper Positioning and Unbuckling of a Restraint System on a 10-Year-Old Child ATD in a Far Side Side-Impact Environment2026-01-05624/7/2026
Five sled tests were performed with a Hybrid III (H-III) 10-year-old child sized Anthropomorphic Test Device (ATD) positioned in the 2nd row left seat of a three row 2006 Sport Utility Vehicle (SUV). A HYGE Sled buck was positioned to represent/replicate a side impact collision to the passenger (right) side of the SUV, with a Principal Direction of Force (PDOF) of 60 degrees, resulting in a far side side-impact for the ATD. Of the 5 tests performed, three of the five tests were performed with a delta-V of 17 mph, and two of the tests at a delta-V of 24 mph. Of the 17 mph tests, one test was performed with a properly restrained ATD, and two tests performed with improper restraint positioning. Both of the 24 mph tests were performed with improper restraint positioning, effectively identical to the two 17 mph delta-V tests. The two improper restraint use tests (at both 17 and 24 mph delta-V) included two different improper restraint scenarios. The first scenario of improper restraint positioning involved moving the torso belt from the left shoulder, over the head, and onto the right shoulder. The second scenario involved the same belt re-positioning as the first scenario, but additionally a disengaged latch plate from the buckle, essentially creating a condition of seat belt entanglement. Each of the five tests utilized its own salvage-vehicle-harvested seat belt assembly, originating from the same model series of SUV. All tests were documented with 4 high-speed video cameras. Occupant kinematics and seat belt physical evidence were analyzed and compared across the test series. Head accelerations and upper neck loads were also evaluated. The results demonstrated the uniqueness of physical evidence left behind on components of the seat belt system, both in terms of locations of the evidence as well as the extent and geometric orientation of the evidence, across the three demonstrated scenarios (proper, improper, and improper and unbuckled). Additionally, the three scenarios exhibited significant differences with respect to the head accelerations and neck loads experienced by the ATD.
Luepke, Peter, Hewett, Natalie, Betts, Kevin, Van Arsdell, William, Weber, Paul, Stankewich, Charles, Miller, Gregory, Watson, Richard, Sochor, Mark
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
Crashworthiness of WC19 Wheelchairs in Horizontal Dynamic Aircraft Seating Tests09-14-02-00011/23/2026
At present, commercial air travel rules do not allow people to sit in their own wheelchairs during flight. However, airline seating often does not meet medical needs. In response to current requests to allow this seating option, we researched the crashworthiness and safety of wheelchairs for potential use in aircraft. For motor vehicle travel, many wheelchairs meet voluntary standards for crashworthiness and safety per RESNA WC19. This project assesses whether WC19-compliant wheelchairs can meet FAA aircraft seating standards when secured using 4-point tiedowns. For the FAA horizontal impact testing, computer modeling indicated that a trapezoidal sled pulse was sufficient to represent the more typical triangular pulse, and that due to the flexibility of the tiedown webbing, the effect of the simulated pitch/roll element was minimal. During the initial two horizontal impact tests, fracture of the left front wheelchair caster was observed. The remaining five wheelchairs were tested with an added vehicle-mounted lap belt and were successful at meeting occupant retention and structural integrity requirements. The outcomes show that it may be possible for people to remain seated in a WC19-compliant wheelchair for air travel without a significant decrement in safety.
Klinich, Kathleen D., Manary, Miriam A., Boyle, Kyle J., Vallier, Tyler, Orton, Nichole R.
Addressing Safety Belt Discomfort among Female Driving Population through Data Collection and Simulation2026-26-00161/16/2026
The number of female drivers in India is increasing alongside the rapid growth of the Indian automotive industry. A driving comfort survey conducted among female drivers revealed that many of them experienced discomfort when wearing safety belts—while driving and as front-seat passengers. This discomfort is primarily due to a phenomenon referred to as “neck cutting.” The root cause of neck cutting is likely related to vehicle design, which is traditionally based on Anthropometric Test Devices (ATD’s) representing the 5th, 50th & 95th percentile (%tile) of the global population. However, a literature review indicated that the anthropometric dimensions of the Indian populations are generally smaller than those of the global for the respective candidate. To validate the neck-cutting issue, various female candidates were asked to sit in the Driver’s seat for physical measurements trials. Accordingly, methodology was developed to quantify neck cutting parameters objectively. A correlation study was performed to align virtual simulation results with physical trials outcomes, to fine-tune the virtual methodology. Based on the findings, few recommendations were suggested which were evaluated against its effect on existing relevant standards.
Kulkarni, Nachiket A, Chitodkar, Vivek V, Eknath Chopade, Santosh, Mahajan, Rahul, Yamgar, Babasaheb S
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
Quantifying Naturalistic Changes in Occupant Postures in Belt-Positioning Booster Seats Utilizing Pressure Mats2025-22-000812/2/2025
Belt-positioning booster seats (BPBs) help promote proper seat belt fit for children in vehicles. The effectiveness of BPBs depends on occupant posture, which can be influenced by BPB design features. This study aimed to quantitatively describe how children's postures naturally change over time in BPBs, using pressure mats. Thirty children aged 5 to 12 participated in two 30-minute trials using randomly assigned seating configurations. Five configurations were studied by installing two backless BPBs in vehicle captain’s chairs, varying booster profile (high, low, or no BPB) and armrest presence (with or without BPB/vehicle seat armrests). TekScan 5250 pressure mats were placed on the seating surfaces. Children began in an ideal reference posture, and center of force (COF) data were collected continuously. Additional observations on posture, behavior, and comfort were periodically collected. Mixed models, including effects of seating configuration, time, and volunteer characteristics, were used to explore changes in COF position from the reference position with time. Children assumed a variety of postures. Over time, children showed a statistically significant forward COF shift of 2.5 cm from the initial posture across all trials (p = 0.003). No significant differences were found in the average COF position or translation between seating configurations in the fore-aft (x) or inboard-outboard (y) directions. However, the maximum and cumulative COF translation in the x-direction was significantly influenced by booster profile, with high-profile configurations resulting in the least amount of translation. Children tended to slouch over time, as evidenced by an average forward COF translation of 2.5 cm over thirty minutes. These findings were supported by video footage and posture data. Trends toward forward COF translation were most apparent in low-profile and no booster configurations. Such changes in booster occupant postures can imply increased injury risk, specifically associated with submarining as evaluated in previous computational investigations. Future research should examine these trends in real-world driving environments and assess how specific BPB design elements may support better long-term posture during vehicle travel.
Connell, Rosalie, Baker, Gretchen H., Mansfield, Julie A.
Monitoring the Injection Molding Process to Improve Quality and Lower CostsTBMG-5389710/1/2025
When it comes to plastics applications, cars are rarely the first products that come to mind. However, with modern vehicles containing 1,000 to 1,500 plastic parts — including dashboards, control elements, clips, trim parts, brackets, door panels, bumpers, and radiator grilles — the material is more important for mobility than we might assume. Some of these plastic parts are relevant for the drivers’ safety: for instance, airbag covers must open correctly in an accident and seat belt guides and retractors could cause severe injuries if they break or deform under load. Their quality is vital. At the same time however, cost pressure and new regulations — for instance regarding an increased use of recycled materials that is under way in the European Union — pose new challenges, especially in plastic injection molding. Digital solutions for measurement technology help control and stabilize the complex process and may even lead to increased product quality despite tougher conditions.
Design and Analysis of Passive Controlled Plastic Hinge in Two-Post Rollover Protective Structure for Off-Highway Motor Grader Equipment02-19-01-00017/23/2025
Rollover protective structures (ROPS) that absorb energy during vehicle rollovers play a crucial role in providing integrated passive safety for operators restrained by seat belts. These protective structures, integrated into the vehicle frame, are designed to absorb high-impact energy and deform in a controlled manner without intruding into the occupant’s safe zone. This research focuses on the detailed analytical design procedure and performance evaluation criteria of the two-post open ROPS used on motor graders against lateral loads. An experimental test on a standard tubular square hollow section (SHS) column subjected to lateral load has demonstrated a significant correlation between the post-yield behavior of plastic hinge development and energy absorption, compared with results from various formulations adopted in finite element analysis (FEA). To reduce design iteration time and the cost of physical destructive testing, the complete equipment experimental setup is virtually simulated, building upon a thorough understanding of plastic hinge formation on columns under large deflections. This simulation provides comprehensive insights into the structural elasto-plastic response and employs the nonlinear implicit and explicit schemes of FEA to accurately predict energy absorption and force vs deflection behavior. The study follows the guidance outlined in ISO 3471: 2008 standard specifications, validating key structural performance parameters through virtual CAE simulation to ensure alignment with the standard’s force and energy requirements. The research emphasizes the control of merging empirical and analytical methods with advanced CAE tools, allowing engineers to design and evaluate ROPS with superior energy absorption and minimal deflection. By adopting this holistic approach, designers can significantly enhance ROPS structural integrity, ensuring improved safety and protection for operators in the demanding conditions of off-highway vehicles.
J., Avinash
Structural Strength Evaluation of the Lightweight Frame of Bus Passenger Seat with High-Tensile Material and Analysis of the Importance of Independent Variables by Regression02-18-04-00225/10/2025
This study aims to develop a lightweight bus passenger seat frame by conducting structural nonlinear finite element analysis (FEA) on various thickness combinations of seat frame components to identify the optimal configuration. The thicknesses of critical structural members that primarily bear the load when force is applied to the seat frame were selected as independent variables, while stress on each component and compliance with ECE R14 seatbelt anchorage displacement regulations were set as dependent variables. A regression analysis was performed to calculate the importance of each component and analyze the influence of each design variable on the dependent variables. Strain gauges were attached to critical areas of the actual seat frame to conduct a seatbelt anchorage test, and simulations under identical conditions were performed using the nonlinear FEA software (LS-DYNA) to validate the reliability of the analysis results. The optimized seat frame exhibited a maximum stress of 734 MPa and a displacement of 300.5 mm, satisfying the ECE R14 compliance criteria. A total of 81 scenarios with varying thickness combinations for the seat frame components were generated, and the results of each scenario were used to analyze the importance of design variables on the seat frame’s structural strength. The regression model achieved an R2 value of 0.927, confirming its reliability in predicting the structural response. These findings contribute to the development of optimized lightweight seat frames that enhance both safety and weight efficiency in commercial vehicles.
Ko, Yeong Gook, Cho, Kyu Chun, Lee, Ji Sun, Kang, Ki Weon
Analysis of Occupants' Responses in Frontal Sled Tests under a Reclined Rigid Seat Environment2025-01-87344/1/2025
With the increasing adoption of Zero-Gravity Seats in intelligent cockpits, there is a growing concern over the safety of occupants in reclined postures during collisions. The newly released anthropomorphic test device (ATD), THOR-AV, has modified the neck, spine, and pelvis structures to better match reclined postures. This study aims to investigate the changes in kinematic response and injury metrics for occupants in reclined postures, through high-speed frontal sled tests utilizing the THOR-AV. The tests were conducted using an adjustable rigid seat with a zero-gravity characteristic and an integrated three-point seat belt. Six tests were performed across four seat configurations: Standard, Semi-Reclined, Reclined, and Zero-gravity postures. The input acceleration pulse for these tests was derived from the equivalent double trapezoidal waveform of the Mobile Progressive Deformable Barrier (MPDB) test. Data from sensors and high-speed video were collected for analysis. The results indicated that with an increasing seat back angle, the degree of head flexion relative to the torso and neck load increased, with abnormal contact between the shoulder belt and neck. After posture reclining, the forward displacement of the ATD's torso increased, with a concomitant increase in lower chest compression, a decrease in thoracic forces, and a significant rise in lumbar axial forces. The zero-gravity posture exhibited submarining, as inferred from the iliac force reduction rate and video analysis. These findings provide critical insights for optimizing occupant restraint systems in reclined postures. Furthermore, the simplified rigid seat sled test environment demonstrated in this study is conducive to modeling and validation, suggesting the potential for further simulation-based investigations.
Wang, Qiang, Liu, Yu, Fei, Jing, Yang, Xiaoting, Wang, Peifeng, Bai, Zhonghao
Analysis and Comparison of Metrics to Assess Submarining Behavior with the Hybrid III 5th Percentile Dummy in the Rear Seat2025-01-87114/1/2025
Real-world data show that abdominal loading due to a poor pelvis-belt restraint interaction is one of the primary causes of injury in belted rear-seat occupants, highlighting the importance of being able to assess it in crash tests. This study analyzes the phenomenon of submarining using video, time histories, and statistical analysis of data from a Hybrid III 5th female dummy seated in the rear seat of passenger vehicles in moderate overlap frontal crash tests. This study also proposes different metrics that can be used for detecting submarining in full-scale crash tests. The results show that apart from the high-speed videos, when comparing time-series graphs of various metrics, using a combination of iliac and lap belt loads was the most reliable method for detecting submarining. Five metrics from the dynamic sensors (the maximum iliac moment, maximum iliac force drop in 1 ms, time for 80% drop from peak iliac force, maximum pelvis rotation, and lumbar shear force) were all statistically significant predictors of submarining, but the presence of a rear seat-belt pretensioner was not significant. Though no one metric was able to provide accurate submarining judgement in all the cases, a combination of these significant metrics can be used along with video to gain more confidence in submarining judgement.
Jagtap, Sushant R, Jermakian, Jessica S, Edwards, Marcy A
Comprehensive Injury Assessment of Reclined Occupants across Varied Seat Configurations with the THUMS Human Body Model2025-01-87394/1/2025
The development of autonomous driving technology will liberate the space in the car and bring more possibilities of comfortable and diverse sitting postures to passengers, but the collision safety problem cannot be ignored. The aim of this study is to investigate the changes of injury pattern and loading mechanism of occupants under various reclined postures. A highly rotatable rigid seat and an integrated three-point seat belt were used, with a 23g, 50kph input pulse. Firstly, the sled test and simulation using THOR-AV in a reclined posture were conducted, and the sled model was verified effective. Based on the sled model, the latest human body model, THUMS v7, was used for collision simulation. By changing the angle of seatback and seat pan, 5 seat configurations were designed. Through the calculation of the volunteers' pose regression function, the initial position of THUMS body parts in different seat configurations was determined. The responses of human body parts were output, including kinematics, biomechanics and kinetics. The results show that the bending state of spine in motion changes with the reclined posture changing, and more attention should be paid to the injuries of the head, chest, lumbar vertebra and pelvis. As the tilt increased, there was an increased likelihood of abnormal belt-neck contact, and the deflection of the ribcage and loading mechanism of lumbar spine changed. Raising the seat pan could help prevent significant pelvis excursion and injury. The findings will help to guide the design of inclined occupant protection and provide theoretical guidance for future crash safety evaluation.
Yang, Xiaoting, Wang, Qiang, Liu, Yu, Fei, Jing, Wang, Peifeng, Li, Zhen, Bai, Zhonghao
Machine Learning-Enabled Optimization of Vehicle Restraint Systems – Demonstration in a Real-World Crash Scenario2025-01-87224/1/2025
Vehicle restraint systems, such as seat belts and airbags, play a crucial role in managing crash energy and protecting occupants during vehicle crashes. Designing an effective restraint system for a diverse population is a complex task. This study demonstrates the practical implementation of state-of-the-art Machine Learning (ML) techniques to optimize vehicle restraint systems and improve occupant safety. An ML-based surrogate model was developed using a small Design of Experiments (DOE) dataset from finite element human body model simulations and was employed to optimize a vehicle restraint system. The performance of the ML-optimized restraint system was compared to the baseline design in a real-world crash scenario. The ML-based optimization showed potential for further enhancement in occupant safety over the baseline design, specifically for small-female occupant. The optimized design reduced the joint injury probability for small female passenger from 0.274 to 0.224 in the US NCAP frontal 56.8 km/h rigid barrier impact condition. In a reconstructed field case, the optimized design showed potential reduction in chest injury risk probability from 49% to 35% for an older female passenger. This study demonstrates the efficacy and generalizability of ML-based optimization in vehicle restraint system design, highlighting its immense potential to enhance occupant safety if there is an adaptive restraint in the vehicle.
Lalwala, Mitesh, Lin, Chin-Hsu, Desai, Megha, Rao, Shishir
Assessment of Injuries in Rear Impacts2025-01-87274/1/2025
Rear impacts make up a significant portion of crashes in the United States. To date, regulations on rear impacts have focused on fuel system integrity and seat performance, while most research has focused on seat performance in relation to occupants’ injuries, with some analyses of crash severity and seat belt effects. The performance of seats and seat belts may vary depending on the size of the occupant. Understanding how occupant characteristics, as well as crash scenarios, affect injury outcomes can show opportunities for further enhancements in rear impact occupant protection. This paper presents analyses using survey weighted logistic regression models to understand the factors affecting serious injury outcomes (i.e., MAIS 3+) in rear impacts, exploring the potential for improving occupant outcomes. Three separate models are evaluated, focusing on 1) overall injury level, 2) head, neck, and cervical-spine injuries, and 3) thorax, abdomen, thoracic- and lumbar-spine injuries for drivers in rear impacted passenger vehicles. Results show that significant factors vary by injured body region and highlight potential opportunities for enhancing occupant protection.
Greib, Joshua, Jurkiw, Renee, Kryzaniwskyj, Tanja, Owen, Susan, Van Rooyen, Paul, Whelan, Stacey, Williamson, John
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
PYROTECHNIC PRETENSIONER REQUIREMENTS AND VALIDATIONUSCAR48 (Current)2/25/2025
This specification establishes the minimum required performance and validation for the seatbelt pyrotechnic pretensioners integrated into retractors, buckles, and/or anchors. It also includes pyro for switchable load limiters. This specification is intended to focus on the performance of the tensioner function integrated into the aforementioned devices and NOT the entirety of the device integrated into the vehicle. See Figure 1 in 2.2.
USCAR
Finite Element Comparison of Human and Hybrid III Responses in the Airworthiness Certification of Normal Aircraft2024-01-701811/15/2024
With the capability of predicting detailed injury of occupants, the Human Body Model (HBM) was used to identify potential injuries for occupants in car impact events. However, there are few publications on using HBM in the aviation industry. This study aims to investigate and compare the head, neck, lumbar spine and thoracic responses of the Hybrid III and the THUMS (Total Human Model for Safety) model in the horizontal 26g and vertical 19g sled tests required by the General Aviation Aircraft Airworthiness Regulations. The HIC of THUMS and Hybrid III did not exceed the requirements of airworthiness regulations. Still, THUMS had higher intracranial pressures and intracranial stresses, which could result in brain injury to the occupants. In vertical impact, the highest stress of the neck of THUMS appears at the cervical spine C2 and the upper neck is easily injured; in horizontal impact, the cervical spine C7 has the highest load, and the lower neck is easily injured. Due to the low biofidelity of the Hybrid III ATD neck structure, the injuries that appeared at different neck locations cannot be identified by the Hybrid III ATD. Because of the submarining phenomenon, the lumbar spine load and bending moment of the THUMS are much smaller than that of the ATD model, which shows a lower risk of injuries. In both impact scenarios, the THUMS chest deformation was higher. In the vertical 19g impact, the THUMS developed much higher shoulder belt loads than the ATD. The results indicate the Hybrid III ATD underestimates the risk of injury to passengers' heads and chests, while overestimating the risk to the lumbar spine compared to THUMS. Furthermore, due to limitations in the locations of sensors, the Hybrid III ATD is unable to identify the severe injury at lower neck and upper lumbar.
Shi, Xiaopeng, Ding, Xianghe, Guo, Kai, Liu, Tianfu, Xie, Jiang
Determination of Postmortem Human Subject Response to Vertical Drop Tower Testing and Initial Application for Total Human Model for Safety Finite Element Model Validation09-12-02-001511/12/2024
Drop tower testing was conducted using 50th percentile male PMHS at 15G peak acceleration in a rigid seat, with a seat pan-to-seatback angle of 90°. Subjects were instrumented with 6DOF motion blocks at T1, T4, T12, L3, and S1 to capture detailed vertebral body kinematics. Pressure sensors were also placed throughout the lumbar spine to estimate force in the intervertebral discs from S1-L2. PMHS were restrained using a pilot torso harness attached to the seat at the shoulders and lap belt, both pretensioned to 89 N. Reaction forces were measured in the seat using six-axis loads under the seat pan. Final positioning of the occupant was documented using a FARO arm point probe and laser scanner. To recreate the experimental setup, CAD models of the experimental fixture were meshed using a commercial FE modeling software (Hypermesh) and imported into LS-Dyna for incorporation with the THUMS model. The belt routing tool in LS-PrePost v4.9.12 was used to develop the torso harness and shoulder and lap belts. Pre-simulation was performed to position the THUMS model in accordance with recorded FARO data, and the experimentally recorded seat vertical acceleration was assigned using Boundary_Prescribed_Motion. Finally, instrumentation locations were duplicated within the THUMS model to match the PMHS experimental setup. The THUMS model showed similar head kinematics compared to the experiment, which went first into extension, followed by flexion during the primary pulse. The torso of the model, however, experienced an increased flexion/compression response compared to PMHS. The peak reaction force in the simulated seat load cells measured 12.7 kN, which was within one standard deviation of the average normalized experimental values (average = 12.8 kN, standard deviation = 0.4 kN). The average load in the lumbar spine in the model was found to be 3.3 kN, which was lower than PMHS average by more than two standard deviations.
DeWitt, Timothy R., Marcallini, Angelo M., Bolte IV, John H., Kang, Yun-Seok
Repositioning Forward-Leaning Occupants with a Pre-Pretensioner Belt in Static Conditions09-12-02-001911/12/2024
Extreme out-of-position pre-crash postures may need high-force pre-pretensioner (PPT) for effective repositioning (Mishra et al., 2023). To avoid applying a high force on the chest, we hypothesized that in case of these extreme postures the PPT may be activated in the absence of a pre-crash motion as a cautionary measure. Therefore, the aims of this study were: (1) to understand the effect of the PPT in repositioning a forward-leaning occupant in static conditions and (2) to characterize occupants’ kinematic variability during repositioning. Sixteen healthy volunteers (8 males, 8 females, 23.8 ± 4.2 years old) were seated with a 40° forward posture on a vehicle seat and restrained with a 3-point seat belt equipped with a PPT. Two PPT seatbelt conditions were examined: low PPT (100 N) and high PPT (300 N). Head and trunk rearward displacements relative to the initial forward-leaning position at 350 ms from PPT onset were collected with a 3D motion-capture system and compared between sexes, repetitions, and PPT levels with repeated measure 3-way ANOVAs (p-level = 0.05). Head and trunk rearward displacements were greater with the high PPT (head −93.8 ± 9.3 mm, trunk −78.7 ± 6.7 mm) than the low PPT (head −44.6 ± 8.9 mm, trunk −39.7 ± 7.6 mm) (p < 0.001). There were no statistically significant differences between sexes (p > 0.19), repetition (p > 0.28), and no interaction effects (p > 0.18). There was greater inter-subject variability in the low (head −109.5 to −22.1 mm, trunk −105.0 to −17.5 mm) compared to high PPT (head −175.0 to −62.5 mm, trunk −128.4 to −54.8 mm). Although no sex differences were found, the high inter-subject variability suggests that PPT timing and force level might not be designed as one-size-fits-all. This study shows that triggering the PPT when the vehicle is traveling at a constant speed could reduce the PPT force needed to reposition forward-leaning occupants during pre-crash maneuvers.
Witmer, Maitland, Griffith, Madeline, Graci, Valentina
Evaluation of Child Anthropometries in Relation to Modern Vehicle Seat and Booster Dimensions2024-22-000410/30/2024
This study compared modern vehicle and booster geometries with relevant child anthropometries. Vehicle geometries (seat length, seat pan height, shoulder belt outlet height, and roof height) were obtained for 275 center and outboard rear seating positions of US vehicles (MY 2009–2022). Measurements of 85 US boosters (pan height and pan length) and anthropometries of 80 US children between 4–14yo (seated height, thigh length, leg length, and seated shoulder height) were also collected. Comparisons were made between vehicles, boosters, and child anthropometries. Average vehicle seat lengths exceeded child thigh lengths (+9.5cm). Only 16.4% of seating positions had seat lengths less than the child thigh length mean+1SD. Even for children at least 145cm, only 18.8% had thigh lengths greater than the average vehicle seat length. Child thigh lengths were more comparable with average booster seat pan lengths for all multi-mode and high-back designs (-2.0cm) and low-back boosters (+3.1cm). The average observed booster pan height (9.9cm) would help most children achieve seated shoulder heights similar to the Hybrid III 5th percentile Female ATD. Compared to vehicle seats, booster geometries were more compatible with child thigh lengths and assist children in achieving seated shoulder heights more comparable to the vehicle restraint system. This emphasizes the continued need for shorter vehicle seat cushion lengths for these occupants and the need to educate caregivers and promote booster recommendations which highlight the importance of achieving proper belt fit and avoiding slouched postures, even for children greater than 8 years and/or 145cm.
Baker, Gretchen H., Connell, Rosalie R., Rhodes, Carrie A., Mansfield, Julie A.
Occupant Positioning Study during Pre-Crash and Integrated Safety Restraint System2024-28-000210/17/2024
The primary purpose of the active safety feature is to reduce the danger of a collision between the car and an obstruction. To improve occupant safety, active safety systems must be included on all new vehicles; nonetheless, not all incidents are preventable. The frequency of incidents on the road has recently increased in tandem with the number of cars, making it critical to investigate the crashworthiness of a vehicle because human life is at the top of the priority list. This study examines an occupant's responses prior to a crash event, as well as studies into how occupant posture influences injury data. Most of the existing research focuses on the pre-crash event or the occupant's optimal seated position. However, it is critical to understand an occupant's reflex or behavior during the pre-crash event, when the occupant is typically not in an appropriate seating posture due to the panic reflex. As a result, an occupant's reflex in a panic situation will change their seating posture, affecting their injury parameters. The study will be based on the finite element crash simulation methodology for accident situations in compliance with the FMVSS rules. A comparison of injury parameters between a typically positioned occupant and an out-of-position occupant is presented. As a part of future work, we can consider restraint system method for reducing injuries to an occupant in a crash. A parametric study of the restraint system can be performed to identify strategies to reduce occupant injuries. One such example is the crisscross seatbelt. Existing restraint system solutions can be fine-tuned based on occupant injury levels in various seating positions.
Shankara Murthy, Santosh, Srinivasa, Praveen, CK, Umesh, Patil, Shubham, Jois, Rahul
ZF's latest safety advances open up, tighten up and DOUBLE DOWN24AUTP08_028/1/2024
ZF rethinks safety with new airbags, belt tensioner. ZF knows that the steering wheel remains one of the most relevant components in an automotive interior, because this is where drivers have direct contact to the vehicle. As steering wheels become adorned with more functions than some drivers know what to do with, ZF put Marc Schledorn in charge of the teams rethinking how the driver airbag could operate in a world with ever-busier steering wheels. The solution is a new type of steering wheel airbag that ZF Lifetec (ZF's renamed Passive Safety Systems division) announced in June. Instead of moving through a thermoplastic airbag cover mechanically fixed in the center of the wheel, Schledorn told SAE Media, the new design positions the airbag on the top side of the steering wheel and then expands through the upper rim of the wheel when needed.
Blanco, Sebastian
Evaluation of the Full-Frontal Crash Regulation for the M1 Category of Vehicles from an Indian Perspective2024-01-27504/9/2024
Background: The Indian automobile industry, including the auto component industry, is a significant part of the country’s economy and has experienced growth over the years. India is now the world’s 3rd largest passenger car market and the world’s second-largest two-wheeler market. Along with the boon, the bane of road accident fatalities is also a reality that needs urgent attention, as per a study titled ‘Estimation of Socio-Economic Loss due to Road Traffic Accidents in India’, the socio-economic loss due to road accidents is estimated to be around 0.55% to 1.35% of India’s GDP [27] Ministry of road transport and highways (MoRTH) accident data shows that the total number of fatalities on the road are the highest (in number terms) in the world. Though passenger car occupant fatalities have decreased over the years, the fatalities of vulnerable road users are showing an increasing trend. India has committed to reduce road fatalities by 50% by 2030. In this context, the automotive industry as well as MoRTH have been taking multiple initiatives including those related to vehicular and road engineering as well as educational measures for raising awareness in the field of road safety. With the intent of lowering road traffic accidents, the government and the ministry are constantly upgrading the requirements related to vehicles, infrastructures, and their implementation thereof. In this context, various future regulations are being deliberated. One such regulation in discussion pertains to requirements for the protection of the passenger car occupants in the event of a full-frontal collision with a focus on restraint systems (AIS 201). This will push manufacturers to design more sophisticated restraints that would help to reduce restraint-induced injuries. The draft version of the standard is available for public input/ discussion. The key objective of the study documented herein is to consider various aspects of the draft standard (AIS 201) from the Indian perspective. This study investigates the research questions, enumerated below: 1 What should be the appropriate test speed for the full-frontal test based on Indian accident data? 2 What is the suitable dummy configuration in terms of gender, seating position, and age to maximize occupant safety in full frontal accidents? 3 Is the proposed ATD’s anthropometry (weight and height) suitable, based on the people involved in full frontal cases in India? 4 What are occupant injury attributes in full-frontal accidents? Key findings/ expected research findings: India has a very different mix of road traffic users and road traffic fatalities compared to that in Europe (Refer to Table 1). Further, issues like seat belt usage are of utmost concern. The demographic for India is also very different from those of developed economies. With India being a country with a rather young population, male and female dummies for driver and front passenger positions should be looked upon. This calls for India-specific safety regulations and research work on automotive test dummies. Practical implications: The study can potentially provide a suggestion for alignment of the regulatory requirements with the actual situations, thereby increasing the effectiveness of the standard.
Mehta, Pooja, Prasad, Avinash, Srivastava, Aakash, Arora, Pankaj, Howlader, Ashim
Study of Indian Road Traffic Accident Characteristics Using Clustering Analysis2024-01-27544/9/2024
In 2021, 412,432 road accidents were reported in India, resulting in 153,972 deaths and 384,448 injuries. India has the highest number of road fatalities, accounting for 11% of the global road fatalities. Therefore, it is important to explore the underlying causes of accidents on Indian roads. The objective of this study is to identify the factors inherent in accidents in India using clustering analysis based on self-organizing maps (SOM). It also attempts to recommend some countermeasures based on the identified factors. The study used Indian accident data collected by members of ICAT-ADAC (International Centre for Automotive Technology - Accident Data Analysis Centre) under the ICAT-RNTBCI joint project approved by the Ministry of Heavy Industries, Government of India. 210 cases were collected from the National Highway between Jaipur and Gurgaon and 239 cases from urban and semi-urban roads around Chennai were used for the analysis. Based on this study, the following results were obtained from (i) Macro Analysis: Accidents on straight roads occur at uncontrolled intersections due to excessive speed. In rugged terrain, accidents occur in rainy and foggy environmental conditions. (ii) From micro analysis - National Highway: Lack of underride guard bars/non-standard guard bars cause serious rear-end crashes, non-use of seat belts in large vehicles increases the likelihood of fatal crashes. One-way divider cuts, rumble strips, safer pedestrian infrastructure, use of roadway lighting, and signage are effective in reducing fatal crashes. The results of this study will help transportation authorities and relevant government policymakers make the necessary decisions to improve road traffic safety.
Vimalathithan, Kulothungan, Rao K M, Pranesh, Vallabhaneni, Pratapnaidu, Selvarathinam, Vivekraj, Manoharan, Jeyabharath, Pal, Chinmoy, Padhy, Sitikantha, Joshi, Madhusudan
Observational Study of Passenger Seat Belt Usage Rates on Shuttle Buses2024-01-27534/9/2024
In 1983, a seat belt use rate survey was published in which 9% shoulder belt use was observed for front-outboard passengers. Nearly forty years later the national estimate of seat belt use has achieved a record high of 91.6% belt use by adult front-seat passengers in 2022. In contrast, there have been very few studies conducted in order to determine seat belt use within large buses and motorcoaches. In 2013, the NHTSA published a final rule amending FMVSS 208 to require seat belts for each seating position in all new over-the-road buses. Beginning in 2016, newly manufactured buses were required to be equipped with lap and shoulder belts for each driver and passenger seat. Recent studies have reported that seat belt use on motorcoaches with relatively long routes was only 2.6%. Similarly, seat belt use in airport shuttle buses was reported to be only 1%. The present observational study was conducted to determine an updated seat belt usage rate of passengers on airport shuttle buses. The aims of this study were two-fold: 1) to personally observe shuttle bus riders and their tendencies to wear or not wear the available seat belts, and 2) to determine whether belt use rates published in recent studies could be confirmed by this study. A single observer completed the shuttle bus trips of this study, which started in July 2022 and continued until July 2023. During each trip, data was recorded for the number of people on the bus and number of people wearing their seat belt. A total of 39 rides on airport shuttle buses in three U.S. cities revealed the seat belt use rate was only 1%, reinforcing previously reported rates.
Gregg, Richard H.
Analysis of Fluid Evidence on Various Vehicle Components2024-01-24674/9/2024
Determining occupant kinematics in a vehicle crash is essential when understanding injury mechanisms and assessing restraint performance. Identifying contact marks is key to the process. This study was conducted to assess the ability to photodocument the various fluids on different vehicle interior component types and colors with and without the use of ultraviolet (UV) lights. Biological (blood, saliva, sweat and skin), consumable and chemical fluids were applied to vehicle interior components, such as seatbelt webbing, seat and airbag fabrics, roof liner and leather steering wheel. The samples were photodocumented with natural light and UV light (365 nm) exposure immediately after surface application and again 14 days later. The review of the photos indicated that fabric type and color were important factors. The fluids deposits were better visualized on non-porous than porous materials. For example, blood was better documented on curtain airbags than side or driver airbags. Blood and chemical fluids were more difficult to document on black than beige seatbelt webbing, while skin showed better on black webbing. Biological fluids were better detected with UV light. The visual presentation did not change substantially between initial and follow-up documentation with and without UV light. Fluids and components with luminescent properties were also factors. This study provides a photodocumentation summary of biological and other fluids on vehicle interior components. In conclusion, UV light exposure was helpful in highlighting some fluid deposits during crash investigation. While UV illumination provided additional insight, further investigation is necessary to discriminate and differentiate fluids present.
Boysen, Kevin, Parenteau, Chantal, Toomey, Daniel, Gregg, Richard H.
Effects of Anthropometry and Passive Restraint Deployment Timing on Occupant Metrics in Moderate-Severity Offset Frontal Collisions2024-01-27494/9/2024
There are established federal requirements and industry standards for frontal crash testing of motor vehicles. Consistently applied methods support reliability, repeatability, and comparability of performance metrics between tests and platforms. However, real world collisions are rarely identical to standard test protocols. This study examined the effects of occupant anthropometry and passive restraint deployment timing on occupant kinematics and biomechanical loading in a moderate-severity (approximately 30 kph delta-V) offset frontal crash scenario. An offset, front-to-rear vehicle-to-vehicle crash test was performed, and the dynamics of the vehicle experiencing the frontal collision were replicated in a series of three sled tests. Crash test and sled test vehicle kinematics were comparable. A standard or reduced-weight 50th percentile male Hybrid III ATD (H3-50M) or a standard 5th percentile female Hybrid III ATD (H3-5F) was belted in the driver’s seating position. In the crash test, the frontal airbag and lap and shoulder belt pretensioners deployed on commands from the vehicle’s airbag control module (ACM). In the sled tests, deployments were commanded with either similar timing or 12 milliseconds earlier. Small, measurable differences in occupant kinematics and biomechanical loading were observed. All biomechanical metrics were low compared to injury assessment reference values (IARVs), consistent with the moderate severity of the tests. The variations in parameters in these tests did not result in suboptimal interactions with restraints, such as submarining, belt webbing migration, or bottoming-out of the airbag resulting in direct occupant loading to the steering wheel. These results indicate that the variations in occupant anthropometry and restraint deployment times investigated did not substantially alter the low risk of serious injuries.
Courtney, Amy, Crosby, Charles, Miller, Bruce, Osterhout, Aaron, Walker, James, Gondek, Jonathon
Research on Occupant Injury Prediction Method of Vehicle Emergency Call System Based on Machine Learning2024-01-20104/9/2024
The on-board emergency call system with accurate occupant injury prediction can help rescuers deliver more targeted traffic accident rescue and save more lives. We use machine learning methods to establish, train, and validate a number of classification models that can predict occupant injuries (by determining whether the MAIS (Maximum Abbreviated Injury Scale) level is greater than 2) based on crash data, and ranked the correlation of some factors affecting vehicle occupant injury levels in accidents. The optimal model was selected by the model prediction accuracy, and the Grid Search method was used to optimize the hyper-parameters for the model. The model is based on 2799 two-vehicle collision accident data from NHTSA CISS (The Crash Investigation Sampling System of NHTSA) traffic accident database.The results show that the model achieves high-precision prediction of occupant injury MAIS level (recall rate 0.8718, AUC(Area under Curve) 0.8579) without excluding vehicle model, and the top 8 relevant features given by the model are: lateral speed change, occupant age, longitudinal speed change, seat belt usage, occupant gender, lateral speed change direction, airbag trigger, and longitudinal speed change direction. We believe that this method can be used to complete organ-level post-crash injury prediction after adding more features, which has great potential to improve the efficiency of traffic accident rescue and reduce the casualty rate.
Huida, Zhang, Liu, Yu, Rui, Yang, Wu, Xiaofan, Fan, Tiqiang, Wan, Xinming
Performance of Five-Point Seat Belt on Occupant Safety in Vehicle on Frontal Crash Test2023-01-51692/23/2024
In day-to-day life, accidents do occur frequently all around the globe. It is difficult to prevent these accidents as they occur due to different reasons, which cannot be easily controlled. However, the fatal injuries occurring to passengers can be reduced by installing efficient safety systems in vehicles, which will help in saving the lives of mankind. Many safety systems are being installed in vehicles such as seat belt restraints, airbags, etc. Generally, three-point seat belts are installed in passenger vehicles for safety purposes. This type of seat belt doesn't arrest the entire motion of the occupant's body during vehicle crashes, which can lead to fatal injuries and sometimes even death during vehicle crashes. To buckle passengers with seats, we can use five-point seat belts which will help in mitigating the injuries as compared to three-point seat belts. In this paper, we evaluate the performance of five-point seat belts on occupant safety during vehicle crashes on flat rigid barriers using LS-DYNA.
Vinodh, T., Dineshkumar, C., Jeyakumar, P.D., Muthiya, Solomon Jenoris, Vinayagam, Nadana Kumar, Christu Paul, R., Dhanraj, Joshuva Arockia
Safer Buses for Passengers and Pedestrians: Crashes and Injury Analyses from Indian and German In-Depth Data2024-26-00041/16/2024
Bus transport is an important element in a sustainable transport strategy. The objective of this study is to understand crashes and injuries involving buses, suggest potential passive-safety interventions, estimate their effectiveness, and compare their effectiveness between Germany and India. Descriptive analysis of crash data from the German In-depth Accident Study (GIDAS) and the Road Accident Sampling System India (RASSI) database was performed in two parts: First, bus passengers and their injuries were analyzed and second, pedestrian injuries in bus-to-pedestrian crashes were analyzed. Lastly, interventions were suggested, and their effectiveness was estimated. Analysis of bus passengers showed that most moderate-to-critical injuries in the GIDAS data were to the head caused by interior bus components. In the RASSI data, head injuries were also frequent, often due to bus interior contact, but also due to ejection and impact to the ground or bus exterior. As many as 31% of all moderate-to-critical injuries in RASSI occurred due to ejection, none in the GIDAS data. Negligible seatbelt usage in the GIDAS data and non-existent use in RASSI demands some explanation. In bus-to-pedestrian crashes, impacts to the front of the bus were the most frequent scenario in both countries. Head injuries were frequent in both GIDAS and RASSI, predominantly due to an impact with the bus front or the ground. To mitigate these injuries, the suggested interventions are seatbelts, pedestrian airbags, and pedestrian underrun protection. These interventions were estimated to annually save up to 180 injured pedestrians and 469 injured bus occupants in Germany, and 5,613 injured pedestrians and 36,271 injured bus occupants in India. To conclude, while the need for better data and more rigorous intervention analysis in future work are discussed, the highlighted safety issues and potential interventions can guide discussion and action plans for safer buses.
Ranmal, Aarti, Jeppsson, Hanna, Strandroth, Johan, Lubbe, Nils
Integration of Seat-Belt Web-Guide Functionality in Trim Part2024-26-00181/16/2024
Restraint systems in automotives are inevitable for the safety of passengers. Seat belts are one such restraint system in automotives that prevent drivers and passengers from being injured during a crash by restraining them back. Seatbelt on automotives has interface with Body-in-white (henceforth called as BIW) and Trim parts in-order to serve its purpose at vehicle level. One such interface part of seat belt is the web guide, which assists and ensures the nylon web’s smooth motion at different seat track positions. Web-guides on automotives ensure the flawless motion of seat belt web at pillar trim areas. In this paper, we are discussing alternate ways of assisting the seat belt web without the web-guide as a separate part. In-order to assist and ensure the motion of nylon web in its trajectory, we have extended the flange of the pillar trim involved. The paper throws light on the advantages of using an extended trim flange as web-guide for seat belt web instead of a separate web-guide (steel) part. A tentative ~80% saving per vehicle has been ensured by eliminating an external web guide and integrating it with pillar trim, without any compromise on the performance criteria.
D, Gowtham, Bornare, Harshad, Gangapuram, Suresh, Deoli, Manish, Ritesh, Kakade, Sai, Konduru, Kakani, Phani Kumar
Application of Taguchi Approach on Wire Electrical Discharge Machining of SS304 for Automotive Applications2023-28-015111/10/2023
SS304 is a type of stainless steel that is well-known for its high ductility and resistance to corrosion; as a result, it is typically utilized in a variety of applications, such as the exhaust systems of automobiles and the springs that are used in seatbelts. Because of its qualities, it will eventually be employed in a variety of body parts, including fuel tanks and chassis, among other things. Due to its properties, SS304 is known to be incredibly difficult to machine using conventional methods. Through a wire electrical discharge machining process, it is easier to cut complex materials with high surface finishes. In this study, a study was conducted on the WEDM process parameters of SS304 to optimize its machining process. The study was carried out using the DoE approach, which involved planning the various experiments. The parameters of the process, such as the pulse on time, peak current, and off time, were analyzed to determine their performance. The various performance measures included surface roughness, overcut, and removal rate. The results of the study were then analyzed with an interaction plot analysis. The influence of the various process variables on the output measures were then studied through this analysis.
Natarajan, Manikandan, Pasupuleti, Thejasree, Katta, Lakshmi Narasimhamu, Somsole, Lakshmi Narayana, D, Palanisamy, Kiruthika, Jothi
Restraint System Optimizations Using Diverse Human Body Models in Frontal Crashes09-11-02-00189/20/2023
Objective: This study aimed to optimize restraint systems and improve safety equity by using parametric human body models (HBMs) and vehicle models accounting for variations in occupant size and shape as well as vehicle type. Methodology: A diverse set of finite element (FE) HBMs were developed by morphing the GHBMC midsize male simplified model into statistically predicted skeleton and body shape geometries with varied age, stature, and body mass index (BMI). A parametric vehicle model was equipped with driver, front passenger, knee, and curtain airbags along with seat belts with pretensioner(s) and load limiter and has been validated against US-NCAP results from four vehicles (Corolla, Accord, RAV4, F150). Ten student groups were formed for this study, and each group picked a vehicle model, occupant side (driver vs. passenger), and an occupant model among the 60 HBMs. About 200 frontal crash simulations were performed with 10 combinations of vehicles (n = 4) and occupants (m = 8). The airbag inflation, airbag vent size, seatbelt load limiter, and steering column collapse force were varied to reach better occupant protection. The joint injury probability (Pjoint) combining head, neck, chest, and lower extremity injury risks was used for the design optimization. Injury risk curves were scaled based on the skeleton size and shape of each HBM. Results and Conclusions: We observed that tall and heavier male occupants tend to strike through the airbag leading to higher head injury risk; older and female occupants tend to sustain higher chest injury risk, while obese occupants tend to have higher lower extremity injury risk. After design optimizations, the average Pjoint was reduced from 0.576 ± 0.218 to 0.343 ± 0.044. The airbag inflation and venting were found to be highly effective in head protection, while the belt load limit and steering column force were sensitive to chest injury risks. Conflicting parameter effects were found between head and chest injuries and among different occupants, highlighting the complexity of achieving safety equity across a diverse population. This study demonstrated the benefit of adaptive restraint systems for a diverse population.
Yang, Zhenhao, Desai, Amoghsidd, Boyle, Kyle, Rupp, Jonathan, Reed, Matthew, Hu, Jingwen
The Impact of Seat Belt Pretensioner Deployment on Forward-Leaning Occupants09-11-02-00199/20/2023
Pyrotechnic seat belt pretensioners typically remove 8–15 cm of belt slack and help couple an occupant to the seat. Our study investigated pretensioner deployment on forward-leaning, live volunteers. The forward-leaning position was chosen because research indicates that passengers frequently depart from a standard sitting position. Characteristics of the 3D kinematics of forward-leaning volunteers following pretensioner deployment determines if body size is correlated with subject response. Nine adult subjects (three female), ages 18–43 years old, across a wide range of body sizes (50–120 kg) were tested. The age was limited to young, active adults as pyrotechnic pretensioners can deliver a notable force to the trunk. Subjects assumed a forward-leaning position, with 26 cm between C7 and the headrest, in a laboratory setting that replicated the passenger seat of a vehicle. At an unexpected time, the pretensioner was deployed. 3D kinematics were measured through a nine-camera motion capture system with reflective markers on the left and right glabella, tragus, manubrium, C7, lateral proximal head of humerus, olecranon process, patella, and lateral malleolus. For uniformity, all pretensioners were of the same model made by Autoliv and were dual systems (having deployment in the retractor and outbound anchor). The initial velocity of the trunk (first 50 ms) was dependent on the body size, with smaller subjects getting pulled back quicker. Following the first ~160 ms, there was a slight rebound where subjects briefly moved forward, followed by a period of high intersubject variance in movement. By isolating the effects of pyrotechnic pretensioner deployment on live volunteers, this study fills in an important gap in automotive safety research and may help with evaluating computer models or designing future restraint systems with advanced sensor technology where pretensioners deploy prior to significant vehicle deceleration.
Hellenbrand, Ciboney, Brown, J. Fletcher, Goodworth, Adam
SAE TOMORROW TODAY: Buckle Up! We're Talking Future Trends134037/17/2023
From AI and ChatGPT to geopolitics and global supply chains, a multitude of trends are converging and paving the way for a historic transformation that will reverberate across industries and sectors. Are you ready? For a rousing conversation that is as wide-ranging as it is thought-provoking, we sat down with Katrin Zimmermann, CEO and Managing Director of TLGG USA, to discuss the trends impacting mobility, technology, globalization, and much more. Fasten your seatbelts for an honest discussion that is certain to push boundaries and open minds.
Hineman, Marcie
Investigation of Potential Injury Patterns and Occupant Kinematics in Frontal Impact with PMHS in Reclined Postures2022-22-00016/27/2023
The reality of the autonomous vehicle in a near future is growing and is expected to induce significant change in the occupant posture with respect to a standard driving posture. The delegated driving would allow sleeping and/or resting in a seat with a reclined posture. However, the data in the literature are rare on the body kinematics, human tolerance, and injury types in such reclined postures. The current study aims at increasing the knowledge in the domain and providing useful data to assess the relevance of the standard injury assessment tools such as anthropomorphic test devices or finite element human body models. For that purpose, a test series of three male Post-Mortem Human Subjects (PMHS) were performed in frontal impact at a 13.4 m/s delta V. The backseat inclination was 58 degrees with respect to the vertical axis. The semi-rigid seat developed by Uriot et al. (2015) was used with a stiffer seat ramp. The restraint was composed of a lap belt equipped with two 3.5 kN load limiters, and of a shoulder belt equipped of a 4 kN load limiter on the upper anchorage placed in the vicinity of the shoulder. The belts, the semi-rigid seat, and the footrest were equipped with force sensors. The rotations of the seat pan and of the seat ramp were also measured. The PMHS were instrumented with multi-axis accelerometers and Y angular velocity sensors attached to the head, thorax (T1 and T12 vertebrae), and sacrum. Strain gauges were glued onto the anterior face of the L1 to L5 lumbar vertebrae and onto the anterior face of the iliac wings. To estimate the pelvis kinematics, a rigid support equipped with targets was fixed onto the femur shaft. Prior to test, X-ray imagery was performed to exhibit the initial curvature of the lumbar spine. After the tests, an in-depth necropsy was done, with a specific attention to the lumbar spine. In the chosen test conditions, no lap-belt submarining was observed for the three PMHS. One PMHS sustained an AIS2 pelvic ring fracture and another one sustained an AIS4 injury with complete separation of the left and right sacroiliac joints. Lumbar disc ruptures and vertebral fractures were observed for the three PMHS (AIS 2 and AIS3 coding). The number of separated rib fractures were very different from one PMHS to another (0, 6 and 33). Response corridors for the external forces and kinematics were built and are presented in the paper. The results are discussed by comparing with existing data for which the backseat was in standard posture.
Baudrit, Pascal, Uriot, Jérôme, Richard, Olivier, Debray, Matthieu
SAE TOMORROW TODAY: Saving Lives With Driver Monitoring Systems133904/24/2023
As the automotive industry moves toward SAE Level 2 and Level 3 autonomy, monitoring driver distraction and encouraging safer driving behaviors is crucial. Driver monitoring systems (DMS) can be lifesaving -- and they are increasingly being required by law in many countries around the world. Cipia is leading this charge with DMS solutions that employ advanced computer vision and AI to monitor the driver's state in real time. Driver Sense detects signs of drowsiness, distraction, seatbelt, holding a phone while driving and more, enabling carmakers to provide lifesaving alerts to the driver. To learn more about this life-saving technology, we sat down with Tal Krzypow, Vice President of Product, to discuss Cipia's advanced computer vision and AI capabilities, in-cabin monitoring and video telematics, and the overall state of DMS technology in markets around the world.
Hineman, Marcie
Lightweight Swivel Seat Frame Concepts Using Advanced Steel Grades2023-01-50214/21/2023
The seat frame to be applied to future autonomous vehicles is expected to be rotatable considering various seating configurations. For the rotatable or swivel seat frame, it might be more difficult to secure passenger-related safety performances including seat belt anchorage (SBA) strength than a conventional seat frame because the conventional seat frame has two seat belt anchoring points on the body center pillar whereas those points of the swivel seat frame should be all located within the rotating structures in the seat frame. Since the swivel seat frame adds a structure for rotation, the mass of the swivel seat frame significantly increases compared to the nonrotatable seat frame, which may become an obstacle to reducing the mass of the vehicle. Currently, there are not many cases of mass production of rotating vehicle seats, and there are hardly any reports of mass reduction through advanced steel materials or corresponding numerical safety performance. In this study, the mass of the swivel assembly, the core part of the swivel seat frame, was reduced by more than 22.8% by establishing a baseline model of the swivel seat frame through benchmarking, applying advanced steel materials to it, and improving the structural design. In addition, a swivel assembly concept with an improved structure for better safety performance was derived, and the steel grade and gauge of the relevant core parts were optimized using a commercial program LS-OPT and various libraries of Python, an open-source programming language. The lightweight concepts and various solutions derived from this study are expected to be a good starting point for applying advanced steel grades to future seat frames.
Kim, Jaehyun
Comparison of Child Restraint System (CRS) Installation Methods and Misuse During Far-Side Impact Sled Testing2023-01-08174/11/2023
Child occupants have not been studied in far-side impacts as thoroughly as frontal or near side crash modes. The objective is to determine whether the installation method of child restraint systems (CRS) affects far-side crash performance. Twenty far-side impact sled tests were conducted with rear-facing (RF) CRS, forward-facing (FF) CRS, high-back boosters, and belt only. Each was installed on second row captain’s chairs from a recent model year minivan. Common CRS installation errors were tested, including using the seat belt in Emergency Locking Mode (ELR) instead of Automatic Locking Mode (ALR), not attaching the top tether, and using both the lower anchors (LA) and seat belt together. Correct installations were also tested as a baseline comparison. Q3s and Hybrid III 6-year-old (6yo) anthropomorphic test devices (ATDs) were used. Lateral displacements of the CRS and head were examined as well as injury metrics in the head, spine, and torso. For RF CRS, the ELR belt installation resulted in a 91 mm (15%) increase in lateral head displacement compared to ALR belt, along with slight decreases in most other injury metrics. Results were similar between installations with LA only and LA + ALR belt together. For FF CRS, the ELR belt condition showed increased lateral CRS displacement compared to ALR belt: +66 mm (9%) without top tether, +93 mm (12%) with top tether. However, head displacements were similar between conditions (approximately 1% difference). Using the top tether decreased head displacements by 12 to 42 mm (2% to 7%, depending on installation method), which is a priority for children since head injuries due to head contact are the most frequent type of injury. Using the top tether slightly increased head injury criterion (HIC36) and neck loads compared to tests without tether. Booster displacement was less for boosters installed with LA and/or top tether compared to belt only installations, but head displacements were similar (<3% difference) regardless of booster installation method. The presence of side wings did not affect peak head displacement but HIC36 was lower in the booster with large side wings compared to the no-wing booster.
Mansfield, Julie
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