Browse Topic: Neck

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Neck and Spinal Responses in the Reclined Large Omnidirectional Child Anthropomorphic Test Device with and without a Booster Seat during Far-Side Lateral Oblique Impacts09-14-01-00115/4/2026
Objective The objective of this study was to examine the Large Omnidirectional Child (LODC) anthropomorphic test device (ATD) neck and spine responses in reclined seating configurations with and without a backless belt-positioning booster (BPB) in far-side lateral oblique impacts. Methods The LODC was seated on a production passenger seat with an integrated seatbelt and tested in nine lateral oblique impact (80° from frontal) sled tests (31.3 km/h). A condition with a nominal seatback angle (~25°) with a backless BPB and two conditions with reclined seatback angles (~45° and ~60°) with and without a BPB were compared. Each condition was repeated, except for the 60° without BPB. Peak upper neck tension force and lateral moment, T1, T6, and T12 lateral rotation, lumbar axial and lateral shear forces, and lumbar axial moment (Mz) were extracted. Results With noBPB, upper neck tension (45° noBPB: 2.0 ± 0.1 kN; 60° noBPB: 1.8 kN) and lateral moment (45° noBPB: 31.7 ± 2.3 Nm; 60° noBPB: 29.2 Nm) were greater than with the BPB in all seatback angles (25° BPB: 1.3 ± 0.04 kN; 21.6 ± 0.1 Nm; 45° BPB: 1.2 ± 0.1 kN, 22.5 ± 2.3 Nm; 60° BPB: 1.2 ± 0.03 kN, 17.6 ± 0.7 Nm). Thoracic spine rotation was smaller in reclined conditions with noBPB (41°–59°) than with BPB (63°–80°). Lumbar axial forces decreased with increasing seatback angle with the BPB (from 2.2 to 1.2 kN). Lumbar Mz showed increasing unbelted shoulder rotation toward the seatback with increasing seatback angle (from 29.8 to 37.8 Nm) with the BPB but not without. Discussion The presence of the BPB may improve neck and spine coupled motion during far-side lateral impacts. However, increased lumbar Mz with the BPB in recline seatbacks requires further understanding.
Graci, Valentina, Humm, John, Hauschild, Hans
Occupant and Seat Responses in Various Moderate- to High-Speed Rear Impact Conditions: Focus on Head-to-Head Restraint Interactions2026-01-05654/7/2026
Head restraint requirements and designs have evolved to minimize the delay in head support and reduce differential loading in the neck. As a result, they have become bigger, closer to the occupant’s head, and angled forward relative to the seat back. Head restraints have been found missing or detached in the field; they may be removed pre-crash due to occupant comfort issues, or post-crash for better accessibility during extrication. Additionally, although rare, head restraints may become detached in severe rear impacts due to occupant loading. To better understand occupant-to-head restraint dynamic interactions, nine rear sled tests were conducted. The test conditions were selected to represent worst case severe loading scenarios. An instrumented 50th Hybrid III ATD (Anthropomorphic Test Device) was lap-shoulder belted on a right-front seat. The neck was equipped with a bracket and lower neck load cell designed for rear impacts. Three series of sled tests were performed wherein the kinematics and kinetics of a restrained ATD were compared across 3 seat configurations: a conventional modern seat, a rigidized modern seat, and an ABTS (all-belts-to seat). Occupant postures evaluated included seated nominally and leaning forward, as may occur in response to hard pre-impact braking and/or an initial frontal impact. Two crash severities were evaluated including a moderate speed (24 km/h delta V pulse based on Euro NCAP) and a very high-speed (49 km/h delta V) condition. Within each series, the sled pulse and ATD initial posture were held constant. The first series (Match #1) was conducted at 24 km/h with a leaned occupant. All biomechanical responses were below IARVs (Injury Assessment Reference Values). The highest responses relative to IARV were for upper and lower neck tension and extension. The Nij was greatest with the ABTS seat for upper neck and with the rigidized seat for lower neck, highlighting the importance of using both the upper neck and lower neck instrumentation. The second series (Match #2) was at 49 km/h with the nominally seated ATD, and the third (Match #3) was at 49 km/h with a leaning forward ATD. The biomechanical responses were below IARV when nominally seated. The biomechanical responses of Match #2 were more favourable than Match #3, highlighting the benefits of early energy absorption during the ride-down. For example, the upper neck Nij was 2.4 in the conventional seat, 4.2 in the rigidized seat and 5.1 in the ABTS. The corresponding lower neck Nij was 4.2, 5.5 and 2.3. The normalized chest 3 ms response was greatest in the rigidized seat, followed by the ABTS, irrespective of sitting posture. There are numerous reasons for an occupant to be out of position prior to a rear impact. In this study, the test conditions were selected to assess head-to-head restraint interactions in severe conditions, including leaning forward. Though the head restraints remained attached in all tests, the results provide insight on the seat and head restraint performance, and head and shoulder loading characteristics, in particular in some non-nominal postures.
Parenteau, Chantal, Burnett, Roger, Davidson, Russell
Effects of Child Anthropometry, Seatback Angle, Seat Rotation Angle, Seatbelt Force Limiting, and Collision Type on Injury Risk of Child Occupants in Highly Automated Vehicles2026-01-05704/7/2026
This study aimed to evaluate the influence of child anthropometry, seating postures (recline and rotation), seatbelt force limiting, and frontal collision scenarios on the kinematic response and injury risk in highly automated vehicles. The TUST IBMs 6YO-O model was conducted the frontal collisions in sled tests. This simulation matrix includes five percentiles six-year-old occupants (P3, P25, P50, P75, and P97), three seatback angles (20°, 30°, and 45°), four seat rotation angles (0°, 90°, 180°, and 270°), three seatbelt force limiting (2.6 kN, 3.6 kN, and 4.6 kN), and three frontal collision types. Injury risks were assessed including the child occupant's head, neck, chest/abdomen, and lumbar region in each simulation (n=540). The results indicate that the child anthropometry, the seatback angle, and the seat rotation angle have a significant influence on the motion responses. Statistically significant differences between all the groups within each independent variable category were observed based on the analysis of variance. As the child dimension increases, the risk of head injury decreases showing by HIC15, while the risk of neck and lumbar injuries increases. As the seatback angle increases, biomechanical parameters of the head show an increasing trend. The risk of upper neck injury decreases, while the risk of lumbar injury decreases and then increases. As the seat rotation angle increases, the risks of head, neck, and chest injuries initially rise and subsequently decrease, while the risk of lumbar injury demonstrates a downward trend. Seatbelt force limiting exhibited a positive correlation with head, neck, and lumbar injury risks. Consequently, small percentile child experiences higher head loads in smart cockpits, with seatback angle and seat rotation angle being key factors contributing to child injuries. These findings highlight the critical need to address the vulnerability of smaller children in smart cockpits by adapting integrated active and passive safety systems to mitigate their injury risk.
Wang, Yanxin, Zhao, Hongqian, Li, Haiyan, He, Lijuan, Cui, Shihai, Lv, Wenle
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
A Study on the Injury Risk of Occupant with Different Head and Neck Rotating Postures under the Frontal Impact Sled Conditions2026-01-05744/7/2026
Drivers obtain road information through head and neck rotation. In order to study the influences of head and neck rotation posture on occupant injury in frontal impact scenario, the THUMS (Total Human Model for Safety) AM50 human body model with five different head and neck rotation postures but without active muscles was adopted to study the biomechanical injury responses of occupant under the frontal impact scenario at 56 km/h in this study. Firstly, the kinematic responses of total body and head acceleration curves at the center of gravity predicted by PMHS (Post Mortem Human Subject) and THUMS AM50 human model under the sled test conditions were compared to verify the simulation model for subsequent study. Then, the THUMS AM50 human model with standard occupant seating posture was adjusted to have five different head and neck rotation postures with 0°, ±20°, and ±40° rotation angle, respectively. Finally, a series of frontal impact sled with or without airbag simulations were conducted for each THUMS AM50 human model with different head and neck rotation postures. The simulation results showed that with the increasing of head and neck rotation angle, the neck injury risk was increased while the thoracic injury risk was decreased. Regardless of whether airbags were present or absent, the model prediction for the standard posture indicated a lower injury risk. And regardless of whether the head and neck posture changed, the airbag always could provide a certain protection in that posture.
Li, Dongqiang, jiang, Yejie, Tan, Chun, Li, Yanyan, Gong, Chuangye, Wu, Hequan, Jiang, Binhui
Use Inertial Sliding of Reclined Seat to Enhance Occupant Retention under Rear-End Crash2026-01-05634/7/2026
Autonomous vehicles may attract more passengers to recline their seat for comfort. However, under severe rear-end crashes and large reclining angle, the backward inertia could completely throw occupant out of seat. Even if the occupant body can be restrained by seatbelt, the occupant’s head could slide out of the head restraint area. Any of these situations may cause severe injuries. To address this safety concern, we developed a sliding seat system designed to enhance occupant retention. Activated by impact inertia of rear-end collision, the system allows the seat sliding backward along its track in a controlled manner, and the sliding stroke is accompanied by a restraint force and absorbs some amount of kinetic energy during the sliding. Thus, occupant retention can be enhanced, and injury risks of head and neck can be reduced. To demonstrate this concept, we built a MADYMO model and conducted a parametric analysis. The model includes a 50th percentile human model, a vehicle seat, and a seat-mounted three-point seatbelt. Under 50 km/h rear-impact load, we evaluated occupant kinematics and critical injury metrics of 45o reclined posture. The relative displacement between occupant pelvis and seatback was used to measure the distance that occupant slides backward, which is a metric for occupant retention. The results have shown that seat sliding distance is the most critical factor for occupant retention, and the longer the sliding distance, the greater the retention effect and the lower the injury risk. In a typical scenario when 200 mm of sliding distance is available for sliding, compared to traditional fixed seat (no sliding allowed), the occupant displacement is reduced by 45%, the Head Injury Criterion value is reduced by 55%, and the Neck Injury Criterion value is decreased by 66%. For vehicle seat design, using the sliding seat system may help off-load the burden of enhancing recliner stiffness, a critical component for maintaining seatback stiffness level in rear-end collisions.
Dai, Rui, Zhou, Qing, Puyuan, Tan, Shen, Wenxuan
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
Detection of Dangerous Driving Postures Based on Depth Images Using an Anchor Regression Method2025-01-734312/31/2025
Perceiving the movement characteristics of specific body parts of a driver is crucial for determining their activity. Moreover, the driver’s body posture significantly impacts personnel safety during collision. This study investigates the creation of a dataset using Kinect depth camera for acquiring, organizing, annotating with skeleton tracking assistance, and optimizing interpolation. The pose recognition methods enhanced through an anchor regression mechanism, leading to the refinement of a lightweight anchor regression network capable of end-to-end learning ability from depth images. The improved backbone neck head structure offers advantages of reduced model parameters and enhanced accuracy. This engineering optimization makes it better suited for practical applications within vehicles with limited computational resources limitations and high real-time demands.
Xu, Hailan, Li, Wuhuan, Lu, Jun, Wang, Xin, He, Wenhao, Chen, Zhenming, Liu, Yunjie
Injury Patterns in Road Traffic Collisions: A Visual Investigation of Affected Body Parts09-13-02-001010/7/2025
Background. Road safety is a major public concern, as road traffic accidents result in numerous casualties and significant economic losses. In traffic collisions, the pattern of injuries sustained by drivers often varies depending on various accident factors. The interactions between safety device use, alcohol consumption status, and injury locations can reveal important association patterns and insights. Therefore, we examine patterns in injury locations, accounting for safety device use and alcohol consumption. Method. In this study, we applied two complementary graphical approaches, including multiple correspondence (MCA) analyses and mosaic plots (MPs). Results. The MPs reveal the existence of meaningful patterns between injury location, alcohol consumption, and safety device. Likewise, the MCA reveals that head/neck injuries are more likely to be associated with alcohol impairment. In particular, sober status and safety device used tend to be associated with all injury locations, excepted head/neck injuries. Furthermore, the chi-square statistic with p < 0.05 rejects the null hypothesis ( H 0 ) of non-association between injury location, safety devices, and alcohol consumption factors. By providing concrete evidence and insights, these findings can inspire policymakers and safety device manufacturers to improve the effectiveness of safety devices.
Chen, Ching-Fu, Wa Lukusa, Martin Tshishimbi
Better Data for Bodies in MotionTBMG-535808/7/2025
The return to Earth is a rough ride for astronauts, from the violent turbulence of atmospheric entry to a jarring landing. Hitting the ground in a Soyuz capsule is the equivalent of driving a car backward into a brick wall at 20 mph, and it’s resulting in more head and neck injuries than NASA computer models predicted. To collect more data, NASA’s Johnson Space Center in Houston commissioned a Small Business Innovation Research (SBIR) project to develop a wearable data recorder for astronaut spacesuits. One result, created by Diversified Technical Systems Inc. (DTS), is a miniature commercial device that now collects and transmits data for any application from airplane test flights to tracking high-value shipments.
Evaluation of Occupant Injury Risk in a Transport Aircraft Crash Test Environment02-18-02-00115/16/2025
Researchers at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) previously conducted a full-scale crash test of a Fokker F28 MK1000 aircraft to study occupant injury risks. The goal of the current study was to investigate the injury predictions of the Global Human Body Models Consortium (GHBMC) and Total Human Model for Safety (THUMS) occupant models in the tested aircraft crash condition and explore possible utilization of both human body models (HBMs) in this context. Eight crash conditions were simulated utilizing each of the models. The HBMs were positioned in two postures, a neutral upright posture with hands resting on the legs and feet contacting the floor and a braced posture with head and hand contact with the forward seat back. Head and neck injury metrics and lumbar vertebra axial force were calculated and compared for all simulations. Both HBMs reported similar kinematic responses in the simulated impact conditions. However, the GHBMC model reported higher forces and injury risks in almost all scenarios. The HBMs were compared to previously modeled anthropomorphic test device (ATD) response. The HBMs showed higher loading than the modeled ATDs in two out of eight impact conditions. Relative to the THUMS model, the GHBMC model had included more virtual instrumentation and produced injury metric values, which encompassed that of the THUMS model. The THUMS model has additional value in being a free access model. Both models provided valuable insight into the potential response of the human body within the simulated aerospace crash environment.
Jones, Nathaniel, Putnam, Jacob, Untaroiu, Costin Daniel
Occupant Responses in High-Speed Rear Sled Tests: Focus of Initial Position, Seat Strength and ATD Size2025-01-87314/1/2025
The National Highway Safety Administration (NHTSA) recently published an Advanced Notice of Proposed Rulemaking (ANPRM) to evaluate seat performance in rear impacts [1]. The ANPRM was issued partially in response to two petitions requesting an increase in seatback strength requirements and high-speed testing with various size Anthropometric Test Devices (ATDs). To better understand the effect of these requests, this study evaluates ATD responses with two high-speed rear sled conditions, three occupant sizes and various seat designs. Seat designs varied from modern conventional seats with yielding properties to stronger and stiffer seats represented by seat integrated restraint (SIR) designs, and rigidized SIR seats. Twenty-four rear sled tests were analyzed. The tests were matched by crash severity, seat designs (strength), ATD sizes and initial postures (nominal/in-position, leaned forward and leaned outboard). The test data and videos were reviewed to identify time coinciding with maximum seatback rotation. Sixteen tests were conducted with the lap-shoulder belted 50th male Hybrid III ATD at 40 km/h, 10 with nominal position and 6 with the ATD leaned forward. In the nominal position, the biomechanical responses were below Injury Assessment Reference Values (IARV); the lower neck Nij was however higher with SIR than non-SIR seats. The gap between the head/upper torso and seat/head restraint increased when the ATD was leaned forward. Compared to nominal position, the responses were higher due to the increase in differential velocity between the ATD and the seat/head restraint. The head, lower neck and chest responses were higher in the SIR than in the non-SIR seats. However, the responses were below IARV except for the lower neck extension in the SIR seat, highlighting the need to support the occupant early in the crash event and the need for yielding properties. Six tests were conducted at 56 km/h with the 5th female Hybrid III, 4 in nominal position and 2 leaned outboard. The biomechanical responses were higher with SIR than non-SIR seats in the nominal position. When the ATD was leaned outboard, the head engaged the SIR rigid structures, resulting in high head responses. Two tests were also conducted with the 95th male Hybrid III at 56 km/h in two SIR seats. The seatback deflected more than 60 degrees, and the normalized biomechanical responses were below IARV. The results from this study indicated that the ATDs’ kinematics were well controlled when the head, neck and torso were centered on the head restraint and when they were supported early in the 40 and 56 km/h rear sled tests. Seatback rotation increased with occupant size. It was higher in non-SIR seats than in SIR seats. The results also showed similar responses with the 5th ATD in a conventional seat and for the 95th in a stronger and stiffer SIR at 56 km/h. In conclusion, seat and occupant responses were favorable with the lap-shoulder belted 50th Hybrid III placed in position in a 40 km/h delta V test, regardless of seat design. The responses were also favorable with the 95th male Hybrid III placed in position at 56 km/h in a stronger seat. However, the responses were unfavorable with the stronger seat with the 5th female Hybrid III at 56 km/h, and/or when the ATD was placed out-of-position. These results highlight concerns with respect to smaller occupants when recommending stronger and stiffer seats, higher test speeds and heavier ATDs.
Parenteau, Chantal, Burnett, Roger
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
The Influence of out-of-Position Displacement during Emergency Braking on Occupant Whiplash Injury in Subsequent Rear-End Collisions2025-01-87204/1/2025
In the pre-crash emergency braking scenario, the occupant inside the vehicle will move forward due to inertia, deviating from the standard upright seating position for which conventional restraint systems are designed. Previous studies have mainly focused on the influence of out-of-position (OOP) displacement on occupant injuries in frontal collisions, and provided solutions such as active pretensioning seatbelts (APS). But little attention has been paid to the influence of OOP on whiplash injury during a subsequent rear-end collision. To investigate the forward OOP impact on whiplash injuries and the effectiveness of APS in this accident scenario, a vehicle interior model with an active human body model (AHBM) was setup in the MADYMO simulation platform. Different braking strengths (0.8g and 1.1g), APS triggering times (from 0.2s before to 0.2s after the braking initiation) and pretensioning forces (from 100N to 600N) were input to the simulation matrix. The occupant’s forward OOP displacement prior to the rear-end collision and the corresponding whiplash injury metrics including neck shear force, tension force, and neck injury criteria (NIC) in the subsequent moderate rear-end collision were recorded. The simulation results indicated that: (1) The occupant’s whiplash injury metrics were positively linearly correlated with the pre-crash forward OOP displacement. (2) The APS could not fully eliminate the forward displacement brought by neck flexion, causing whiplash injury metrics to exceed the capping limits (upper bounds) defined in current vehicle safety assessment protocols like Euro-NCAP.
Fei, Jing, Qiu, Hang, Wang, Peifeng, Liu, Yu, Cheng, James Chih, Zhou, Qing, Tan, Puyuan
The Biomechanical Effects of Neck and Back Cushion / Pillow / Support Devices in Low-Speed Rear Impacts2025-01-87284/1/2025
There are numerous commercially available neck and back support/cushion/pillow devices which are commonly attached to seats by vehicle owners. To our knowledge, there has been no published research on the biomechanical effects of these devices in low-speed rear impacts. To address this, a series of 54 simulated low-speed rear impact tests were conducted using a validated remote-controlled crash sled system. All tests utilized an instrumented BioRID II rear impact anthropomorphic test device (ATD) restrained using a 3-point seatbelt system in a 2018 Toyota Camry LE driver’s seat. Two delta-V ranges were used: a lower range from 7.2 to 8.0 kph (4.5 to 5.0 mph) and a higher range from 10.5 to 11.3 kph (6.5 to 7.0 mph). Six neck only devices, one combination neck and back device, and three back only devices were assessed. Two tests per delta-V range for each device and each device adjustment position were conducted and compared against five reference tests without any devices at each delta-V range. Statistical analyses and comparison of the biomechanical responses between each neck only and back only devices and the reference tests at each delta-V range were conducted. Additionally, Nkm, LNL, WIC, and NIC were calculated for each test. While not all devices and/or delta-V ranges showed consistent effects, the results indicated trends for certain peak biomechanical measures. Specifically, these support devices demonstrated a tendency to increase the tension forces in the upper neck, lower neck, and lumbar spine. Additionally, the back support devices tended to increase the head-to-head restraint contact forces as well as upper neck flexion (positive) moments. This study presents a parametric investigation into the biomechanical effects of various neck and back support/cushion/pillow devices during lower-speed rear impact exposures. The focus is on assessing changes in biomechanical measures associated with the use of these devices, and the injury criteria calculated should only be compared with the reference tests.
Phan, Andrew, Gross, Jamie, Umale, Sagar, Crowley, Shannon, Glasser, Gabriel, Furbish, Christopher
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
A Study on Affections of Active Neck Muscle Force on Neck Injury Responses in Frontal Impact with Automatic Emergency Braking Conditions2025-01-87424/1/2025
Neck injury is one of the most common injuries in traffic accidents, and its severity is closely related to the posture of the occupant at the time of impact. In the current era of smart vehicle, the triggered AEB and the occupant's active muscle force will cause the head and neck to be out of position which has significant affections on the occurrence and severity of neck injury responses. Therefore, it is very important to study the influences of active muscle force on neck injury responses in in frontal impact with Automatic Emergency Braking conditions. Based on the geometric characteristics of human neck muscles in the Zygote Body database, the reasonable neck muscle physical parameters were obtained firstly. Then a neck finite element model (FEM) with active muscles was developed and verified its biofidelity under various impact conditions, such as frontal, side and rear-end impacts. Finally, using the neck FEM with or without active muscle force, a comparative study was conducted on the kinematics and injury responses of the neck in the frontal impact with AEB condition. The research findings indicate that the activation of cervical active muscle forces effectively reduces the displacement of the head's center of gravity prior to the collision and significantly decreases the relative angular displacements between cervical vertebrae during the collision. These dynamic response changes mitigate the injury severity of cervical vertebrae, ligaments, and intervertebral discs, thereby enhancing the biomechanical tolerance of the cervical structure to mechanical loads.
Junpeng, Xu, Gan, Qiuyu, Jiang, Binhui, Zhu, Feng
Literature Review and Framework for Identifying Seat Belt Misuse and Misrouting in Frontal Collisions2025-01-87214/1/2025
The effect of seat belt misuse and/or misrouting is important to consider because it can influence occupant kinematics, reduce restraint effectiveness, and increase injury risk. As new seatbelt technologies are introduced, it is important to understand the prevalence of seatbelt misuse. This type of information is scarce due to limitations in available field data coding, such as in NASS-CDS and FARS. One explanation may be partially due to assessment complexity in identifying misuse and/or misrouting. An objective of this study was to first identify types of lap-shoulder belt misuse/misrouting and associated injury patterns from a literature review. Nine belt misuse/misrouting scenarios were identified including shoulder belt only, lap belt only, or shoulder belt under the arm, for example, while belt misrouting included lap belt on the abdomen, shoulder belt above the breasts, or shoulder belt on the neck. Next, the literature review identified various methods used to assess misuse/misrouting including testimonies and physical evidence on the occupant (i.e., belt marks/injury pattern) and on the vehicle interior and/or restraint system (i.e., loading marks). The literature review also highlighted the scarcity of test data on this topic, which may be beneficial to help guide technologies used to address and detect such scenarios. A surrogate study with a female volunteer was conducted for each of the nine belt misuse/misrouting scenarios identified from the literature review. The webbing lengths and angles at the hardware were measured. The results provide a first step in documenting evidence that could be part of a crash investigation. Additional studies with various size occupants are suggested, in conjunction with physical and/or mathematical simulation tests. Based on the literature review, a comprehensive and integrated framework to determine belt misuse/misrouting was summarized. The framework is based on information from police and accident vehicle investigation, and medical and radiology records. It also highlighted the need to measure webbing lengths and seat belt hardware angles that can be used in conjunction with surrogate studies and dynamic tests. Technologies such as video footage from in-vehicle cameras have the potential to provide additional data.
Gu, Emily, Parenteau, Chantal
Integration of Muscle Pre-tension and Activation to Evaluate Neck Muscle Strain Injury Risk during Simulated Rear Impacts Using a Finite Element Neck Model2025-22-00012/7/2025
Correia, Matheus A., McLachlin, Stewart D., Cronin, Duane S.
Toward a Test-Based Methodology to Evaluate Unrestrained Torso Neck Braces Using the Hybrid III ATD and MATD Neck09-12-03-001211/23/2024
The introduction of unrestrained torso neck braces as a safety intervention for helmeted motorcycle riders has introduced a set of unsolved challenges. Understanding the injury prevention afforded by these devices depends on a reliable test methodology by which to critically evaluate their efficacy against the most common mechanisms of neck injury. An inverted pendulum test is proposed to evaluate compression flexion (CF), tension flexion (TF), and tension extension (TE) of the neck using a Hybrid III anthropomorphic test device (HIII ATD) neck and a motorcycle-specific ATD (MATD) neck. In addition to investigating methods to quantify the beneficial effects of a neck brace, potential adverse effects of such a device are evaluated by measuring and evaluating relevant neck response measures. To that end, measured data using a current neck brace were analyzed and applied to various injury criteria related to the ATD neck used to compare the injury risk predicted by each parameter. The HIII ATD neck allows for a more conservative evaluation due to its exaggerated response in compression and may be more suitable in evaluating the neck injury criterion and injury risk in CF loading for low energy impacts. The MATD neck is limited to certain impact modalities, particularly the uncoupled behavior between head and neck during hyperextension, and individual neck measures at lower impact energy due to its limited structural integrity in direct head impacts. In the proposed tests, injury mechanisms were initially associated with a pre-impact head orientation and expected head and neck motion. However, these associations are not definitive. Although the most relevant neck injury mechanisms related to the unrestrained torso were addressed, the authors suggest that the presented tests are supplemented by a method to evaluate higher energy vertex impacts as a means to determine a neck brace’s efficacy during this loading modality.
de Jongh, Cornelis U., Basson, Anton H., Knox, Erick H., Leatt, Christopher J.
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
Neck Injury Risk in Out-of-Position Rear Impact Scenarios Using a Reference Geometry-Based Head Repositioning09-12-02-002011/12/2024
Rear-end vehicle collisions may lead to whiplash-associated disorders (WADs), comprising a variety of neck and head pain responses. Specifically, increased axial head rotation has been associated with the risk of injuries during rear impacts, while specific tissues, including the capsular ligaments, have been implicated in pain response. Given the limited experimental data for out-of-position rear impact scenarios, computational human body models (HBMs) can inform the potential for tissue-level injury. Previous studies have considered external boundary conditions to reposition the head axially but were limited in reproducing a biofidelic movement. The objectives of this study were to implement a novel head repositioning method to achieve targeted axial rotations and evaluate the tissue-level response for a rear impact condition. The repositioning method used reference geometries to rotate the head to three target positions, showing good correspondence to reported interverbal rotations. Under a 7 g rear impact scenario, the head-turned models were compared with the neutral position and demonstrated increases in the maximum capsular ligament distractions. Increased head rotation was associated with increased ligament distractions. The locations with critical ligament distractions shifted to the lower cervical spine (below C3) and lateral portion of the capsular ligaments for the head-turned position cases. The proposed repositioning method introduced in this study enabled the model to achieve steady head rotations with realistic cervical spine movements, increasing the biofidelity of out-of-position rear impact simulations.
Reis, Matheus Seif, Cronin, Duane
Quantifying and Comparing the Intersegmental Kinematics of the Pediatric Whole Cervical Spine to Individual Motion Segment Kinematics in a Six-Year-Old Postmortem Human Surrogate09-12-02-001011/12/2024
Mitigating both neck and head injuries in the pediatric population relies heavily on improving our understanding of the underlying biomechanics of the pediatric cervical spine. The tensile response for individual motion segments and the whole cervical spine (WCS) has been reported, but there is no data characterizing the intersegmental kinematics of pediatric WCS under axial loading conditions. The structural response of motion segments and WCS provide valuable data for the design and validation of biofidelic physical and computational models for the pediatric population. However, the use of motion segment data to construct WCS response or the use of WCS axial response to accurately characterize intersegmental response may present limitations to accurately modeling the pediatric cervical spine response. In this secondary analysis of the work of Luck et al. (2008, 2013), the fixed-fixed, low load, quasi-static tensile response of the WCS and individual motion segments (O-C2, C4-C5, and C6-C7) of a six-year-old postmortem human surrogate (PMHS) was investigated to quantify and compare the intersegmental kinematics under both conditions. In the whole spine, O-C2, C3-C4, C6-C7, and C7-T1 exhibited a tensile response, C2-C3 and C5-C6 exhibited a compressive response, and C4-C5 did not exhibit an appreciable response in the axial loading direction. Furthermore, when compared to the tensile behavior of the individual motion segment load-controlled tests, C6-C7 exhibited reduced axial displacement and an increased stiffness at higher loads (≥13.5 N), suggesting the recruitment of more superficial ligamentous layers that span multiple vertebrae in the whole spine. Regarding vertical displacement and rotation, O-C2 exhibited the largest amount of rotation of 5.57 degrees in flexion and all segments exhibited some amount of anterior–posterior (AP) displacement. The intersegmental kinematics provide biomechanical response data that may support both physical and computational surrogate design and validation as well as data for comparison to isolated FSU testing conditions.
Liu, Miranda, Luck, Jason F.
A Methodology to Evaluate Unrestrained Torso Neck Braces for Near Vertex Impacts09-12-03-00108/22/2024
The advent of neck braces for the helmeted motorcycle rider has introduced a pertinent research question: To what extent do they reduce measures related to the major mechanism of neck injury in unrestrained torso accidents, i.e., compression flexion (CF)? This question requires a suitable method of testing and evaluating the measures for a load case resulting in the required mechanism. This study proposes a weighted swinging anvil striking the helmeted head of a supine HIII ATD by means of a near vertex impact with a low degree of anterior head impact eccentricity to induce CF of the neck. The applied impact was chosen for the baseline (no neck brace) so that the upper and lower neck axial forces approached injury assessment reference values (IARV). The head impact point evaluated represents those typically associated with high-energy burst fractures occurring within the first 20 ms, with possible secondary disruption of posterior ligaments. The proposed test can be used to evaluate the initial and secondary period of neck loading resultant from a near vertex impact and the effect of a neck brace thereon. The presented case study shows that unless almost touching the helmet, neck braces are likely to have a negligible effect on the axial load response of the neck within the first 20 ms after impact and are, therefore, unlikely to affect injury risk related to initial compressive loading of the neck. Conversely, a neck brace can affect neck response in bending during a near vertex CF loading event. Hence, assessing these devices is important to determine their potential in stabilizing the spine. The proposed test shows that the neck loading mechanism does not necessarily correspond with the observed head motion, especially in the early stages of neck response. These head/neck kinetics are important to consider when designing an evaluation load case.
de Jongh, Cornelis U., Basson, Anton H., Knox, Erick H., Leatt, Christopher J.
Seatback Failures and Human Tolerance in Severe Rear Impacts2024-26-00031/16/2024
Seatback and head restraints are the primary restraining devices in rear-impact collisions. The seatback failures expose front seat occupants to dive deep into the rear compartment survival space. Furthermore, it allows the occupants to get in a position with lower spinal tolerance to the impact direction. This paper employs sled tests to demonstrate the dangers of seatback failures in severe rear impact by allowing the occupants to orient their spine in its lowest tolerance zone to the impact direction. Furthermore, the sled test shows the potential of head pocketing phenomena and torso augmentation producing compressive cervical spine loading enough to cause first-order neck buckling. Finally, the results of collapsing seatback dynamics are compared to the strong seatback performance by conducting a similar test with a strong ABTS seatback. The study demonstrates that the strong seatbacks in severe rear impacts produce favorable outcomes while keeping the occupant in their higher spinal tolerance zone to the impact direction.
Thorbole, Chandrashekhar
Virtual Reality Based Study on Pre-Impact Position of Auto Rickshaw Driver2023-28-011811/10/2023
The role of Virtual Reality (VR) platform for experimental studies to mitigate severe injuries is known. A Virtual Reality (VR) module was developed to provide an Indian auto-rickshaw driver experience using commercially available Oculus Quest 2 VR headset. A Driver Behaviour Questionnaire (DBQ) was developed and a study carried out among 20 auto-rickshaw drivers in Thanjavur, India. The DBQ questions provided data to shortlist the most likely near crash experiences among the surveyed drivers. A virtual reality environment was created using UNITY HUB software for one selected scenario from the DBQ survey analysis. A group of 10 volunteers to experience the event using VR gear in the biomechanical laboratory with reflective markers fixed on the body joints of the volunteers to obtain corresponding joint angles in the Neck, Lumbar, Shoulder, Hip, and Knee regions. This study identified various pre-crash reactions from drivers and compared them to the normal driving posture to determine the extent of diversion.
S, Ragul, G, Sundhareswaran, Sankarasubramanian, Hariharan, Prasanna, Selva, Vijayaraghavan, Sriram
Summary of Poster Abstracts09-11-02-00229/20/2023
Eighteen research posters were prepared and presented by student authors at the 18th Annual Injury Biomechanics Symposium. The posters covered a wide breadth of works-in-progress and recently completed projects. Topics included a variety of body regions and injury scenarios such as: Head: Defining the mass, center of mass, and anatomical coordinate system of the pig head and brain; the influence of friction on oblique helmet testing; validation of an in-ear sensor for measuring head impact exposure in American football Neck and spine: Design of paramedic mannequin neck informed by adult passive neck stiffness and range of motion data; identifying injury from flexion-compression loading of porcine lumbar intervertebral disc Thorax: Tensile material properties of costal cartilage perichondrium; finite element models of both an ovine thorax and adipose tissue for high-rate non-penetrating blunt impact Pelvis: Injurious pelvis deformation in high-speed rear-facing frontal impacts Lower extremities: Generation of 3D pediatric femur models from 2D radiographs; plantar thickness and stiffness using ultrasound; knee injuries in skiing and snowboarding using artificial intelligence 3D modeling; jumping kinematics, and kinetics in athletes with secondary task of heading a soccer ball Full body, vehicle occupants: Comparison of Hybrid III, THOR mid-size male, and small female ATDs in frontal sled tests; effects of booster seat on reclined small females during lateral oblique low-acceleration impacts; airbag deployment for out-of-position 50th percentile male human body model Full body, unique loading scenarios: Development of seat fixture and restraints for FE human body model during vertical loading; methodology for PMHS-occupied powered two wheeler and motor vehicle crash scenario
Mueller, Becky, Bautsch, Brian, Mansfield, Julie
Comparison of Head, Neck, and Chest Injury Risks between Front- and Rear-Seated Hybrid III 50th-Percentile Male ATDs in Matched Frontal NCAP Tests09-12-01-00019/19/2023
The objective of this study was to compare head, neck, and chest injury risks between front and rear-seated Hybrid III 50th-percentile male anthropomorphic test devices (ATDs) during matched frontal impacts. Seven vehicles were converted to rear seat test bucks (two sedans, three mid-size SUVs, one subcompact SUV, and one minivan) and then used to perform sled testing with vehicle-specific frontal NCAP acceleration pulses and a rear seated (i.e., second row) Hybrid III 50th male ATD. Matched front seat Hybrid III 50th male ATD data were obtained from the NHTSA Vehicle Crash Test Database for each vehicle. HIC15, Nij, maximum chest acceleration, and maximum chest deflection were compared between the front and rear seat tests, as well as between vehicles with conventional and advanced three-point belt restraint systems in the rear seat. Additionally, a modified version of the NCAP frontal star rating was calculated for the front and rear seat tests. All injury metrics, except for chest acceleration, were higher in the rear seat compared to the front. In addition, injury thresholds were exceeded or nearly exceeded in the rear seat for Nij in three vehicles, chest acceleration in one vehicle, and chest deflection in three vehicles, while no thresholds were exceeded in the front seat. When comparing advanced and conventional restraints in the rear seat, all injury metrics were higher in the vehicles with conventional restraints. All vehicles with conventional restraints in the rear had a star rating of 1, while those with advanced restraints in the rear ranged from 2 to 3. Conversely, all vehicles had 5 stars for the front seat, except one that had 4 stars. Overall, these data highlight the disparity between front and rear seat occupant protection and the benefits of advanced rear seat safety restraints, and the need for future testing.
Bianco, Samuel T., Albert, Devon L., Guettler, Allison J., Hardy, Warren N., Kemper, Andrew R.
User’s Manual for the Small Adult Female Hybrid III Test DummyJ2862_202305 (Current)5/22/2023
This user’s manual covers the small adult female Hybrid III test dummy. It is intended for technicians who work with this device. It covers the construction and clothing, disassembly and reassembly, available instrumentation, external dimensions and segment masses, as well as certification and inspection test procedures. It includes instructions for safe handling of the instrumented dummy, repairing dummy flesh, and adjusting the joints throughout the dummy.
Dummy Testing and Equipment Committee
Hybrid III Ten-Year Old Child Dummy User’s ManualJ2858_202305 (Current)5/1/2023
This user's manual covers the Hybrid III 10-year old child test dummy. The manual is intended for use by technicians who work with this test device. It covers the construction and clothing, assembly and disassembly, available instrumentation, external dimensions and segment masses, as well as certification and inspection test procedures. It includes guidelines for handling accelerometers, guidelines for flesh repair, and joint adjustment procedures. Finally, it includes drawings for some of the test equipment that is unique to this dummy.
Dummy Testing and Equipment Committee
ES2re, WS50M, and Human Body Models in Far-Side Pole Impacts2023-01-05584/11/2023
Driver oblique far-side sled impacts were simulated with three surrogates. The EuroSID side impact dummy with rib extension (ES2re), the WorldSID side impact 50th percentile male dummy (WS50M), and the Global Human Body Modeling Consortium’s 50th percentile male human body (GHBM) models. The versions of the surrogates’ models were 7.0, 7.5.1, and 5.0, respectively. Surrogates were seated in the front left driver seat in a virtual generic crossover sled environment. The Finite Element (FE) based environment consisted of a driver seat, a center console, and a passenger seat. Two restraint systems were considered for each surrogate: belt only (BO) and belt plus a generic seat-mounted far-side impact airbag (BB). Surrogates were restrained using a 3-point belt that has a digressive shoulder force load limiter, and retractor, and anchor pretensioners. The far-side airbag used was a 37-liter in volume and has two chambers. Surrogate head excursions and injury indices for each surrogate were compared. The WS50M kinematics were closer to the GHBM than those of the ES2re. The WS50M predicted 4.7 and 0.5% probability of AIS3+ neck injuries in the BO and BB, respectively. ES2re predicted 48 and 30% probability of AIS3+ thoracic injuries, respectively. Whereas the WS50M predicted 0.5 and 0.0%, respectively. The GHBM had 12 fractures in 8 ribs and no fracture, respectively.
El-Jawahri, Raed E.
Evaluation of Drivers of Very Large Pickup Trucks: Size, Seated Height and Biomechanical Responses in Drop Tests2023-01-06494/11/2023
This study focused on occupant responses in very large pickup trucks in rollovers and was conducted in three phases. Phase 1 - Field data analysis: In a prior study [9], 1998 to 2020 FARS data were analyzed; Pickup truck drivers with fatality were 7.4 kg heavier and 4.6 cm taller than passenger car drivers. Most pickup truck drivers were males. Phase 1 extended the study by focusing on the drivers of very large pickup trucks. The size of 1999-2016 Ford F-250 and F-350 drivers involved in fatal crashes was analyzed by age and sex. More than 90% of drivers were males. The average male driver was 179.5 ± 7.5 cm tall and weighed 89.6 ± 18.4 kg. Phase 2 – Surrogate study: Twenty-nine male surrogates were selected to represent the average size of male drivers of F-250 and F-350s involved in fatal crashes. On average, the volunteers weighed 88.6 ± 5.2 kg and were 180.0 ± 3.2 cm tall with a 95.2 ± 2.2 cm seated height. The volunteers were lap-shoulder belted in the driver seat of a 2002 Ford F-250 crew cab. The head-to-roof clearance was 12.8 ± 1.1 cm. It was 1.0 ± 0.6 cm once the vehicle was statically inverted. Phase 3 – Drop tests: Three drop tests were conducted using 2002 Ford F-250 crew cab pickups. An instrumented 50th Hybrid III ATD was lap-shoulder belted in the driver seat. The ATD was modified by increasing the seated height by 5 cm, from 88 to 93 cm, to represent the average driver of very large pickups. Biomechanical responses were assessed. All were below Injury Assessment Reference Value (IARV) except for upper and lower neck. The effect of roof/pillar deformation on occupant responses was analyzed by varying the vehicle weight (3147 kg in production test v 1502 kg in the buck test) and roof/pillar strength (production v roll caged). The test data and videos were reviewed to identify time coinciding with ground contact, head-to-roof contact, peak biomechanical responses, and maximum deformation. Upper neck compression was -7,426 N in the production test; it was -8.339 N in the buck test and -7,549 N in the roll caged tests. The loads occurred at about 25 msec in all tests. Maximum roof/pillar deformation occurred 150 ms later in the production test. Conclusion: Peak neck compressions were similar in the three tests and occurred shortly after initial head contact and prior to significant roof/pillar deformation. Neck injury responses resulted from torso augmentation and were independent of roof system deformation.
Burnett, Roger, Parenteau, Chantal, Vogler, Michelle, Toomey, Daniel, Orlowski, Kenneth, Krishnaswami, Ram
Development of a Neck Finite Element Model with Active Muscle Force for the THOR-50M Numerical Dummy2023-01-00024/11/2023
With the development of active safety technology, effort has gradually shifted to preventing or minimizing car crashes. Automatic Emergency Braking Technology (AEB) can avoid accidents by warning and even automatic braking, but there is a contradiction between the accompanying occupant out-of-position and traditional passive safety design. In addition, the 2025 version of C-NCAP plans to add neck injury assessment requirements for AEB [1]. In order to study the kinematic response of the occupant's neck under AEB, a neck finite element model with active muscle force is established in this paper. Firstly, the open-source THOR-50M neck geometric model is used for finite element discretization. Secondly, the neck FE model of THOR-50M is verified through the qualification procedure of the NHTSA standard. Thirdly, according to the geometric features of human neck muscles in Zygote Body database, the neck muscle parameters are preliminarily determined. Finally, the neck muscle parameters are corrected based on the occupant out-of-position test under AEB conditions. The benchmarking results show the model can truly reflect the head and neck movements of the occupants under AEB conditions. The neck FE model developed in this work can be used for the development and test evaluation of intelligent occupant restraint systems.
Wu, Xiaofan, Jiang, Binhui, Bai, Zhonghao, Zhang, Guanjun
Development and Calibration of the Large Omnidirectional Child ATD Head and Neck Complex Finite Element Model2023-01-05574/11/2023
The National Highway Traffic Safety Administration (NHTSA) has developed the Large Omnidirectional Child (LODC) Anthropomorphic Test Device (ATD) to improve the biofidelity of the currently available Hybrid III 10-year-old (HIII-10C) ATD. The improvements of the LODC over the HIII-10C include changes in sub-assemblies such as the head and neck, where the LODC head is a redesigned HIII-10C head with pediatric mass properties and the neck has a modified atlanto-occipital joint to replicate observations made from human specimens. The current study focuses on developing a dynamic, nonlinear finite element (FE) model of the LODC ATD head and neck complex. The FE mesh is generated using HyperMesh based on the three-dimensional CAD model. The material data, contact definitions and initial conditions are defined in LS-PrePost and converted to LS-Dyna solver input format. The initial and boundary conditions are defined to replicate the neck flexion experimental tests. Next, an inverse method is used to identify the in-situ material parameters primarily for the highly compliant viscoelastic components and the lumped torque-moment characteristics of the occipital condyle (OC) joint. Material parameters of the viscoelastic components and the coefficients of joint stiffness models are identified by minimizing objective functions based upon the difference between experimental test and the simulation results. The approach is applied to the LODC ATD head-neck complex to improve the predictive capability of the finite element model.
Yang, Peiyu, Katangoori, Divya Reddy, Noll, Scott
Lumbar Flexion Test Procedure for the Hybrid III 50th Male DummyJ3074_202303 (Current)3/20/2023
This procedure establishes a recommended practice for performing a lumbar flexion test to the Hybrid III 50th male anthropomorphic test device (ATD or crash dummy). This test was created to satisfy the demand from industry to have a certification test which characterizes the lumbar without interaction of other dummy components. In the past, there have not been any tests to evaluate the performance of Hybrid III 50th lumbar.
Dummy Testing and Equipment Committee
Development of a New Human Thoracic Equivalent Model during Frontal Impact09-11-02-00071/13/2023
Human thoracic injury under frontal collisions is an inevitable problem in vehicle safety research. Compared with the Multiple Rigid-Body Models (MRBMs) and Finite Element Human Body Models (FEHBMs), Mathematical Equivalent Models (MEMs) can not only provide important data but also improve the research efficiency. The current thoracic MEMs usually adapted the mechanical isolation method to isolate the thorax from the human body; therefore, the effects of the head, neck, and lower body internal organs on the mechanical responses of the thorax are not considered. In this article, a new thoracic MEM, named as Improved Consistent Lobdell Model (ICLM), is developed based on the concentrated mass-spring-damping system to consider the energy absorbed by the deformation of the internal soft tissue and the motion hysteresis of the head, neck, and lower body. Thorax equivalent stiffness curve predicted by the ICLM has a good fit with the corridor obtained by the Post-Mortem Human Subjects (PMHS) experiments under the medium-speed pendulum impact. Based on the parametric and sensitivity analysis, the values of parameters in each subsystem of the ICLM are adjusted to improve the accuracy of different impact tests predicted by the ICLM. The thoracic responses predicted by the adjusted ICLM under the medium-speed pendulum impact were basically consistent with that predicted by the Total Human Model for Safety (THUMS). The relative errors of maximum chest force (Fmax) and maximum chest deflection (Dmax) between the adjusted ICLM model and THUMS are 0.57% and 0.86%, respectively. The adjusted ICLM has good biofidelity and can be applied in the field of automotive engineering in the future.
Liu, Zhixin, Zheng, Hong, Ma, Weijie
User’s Manual for the 50th Percentile Male Hybrid III DummyJ2856_202211 (Current)11/22/2022
The purpose of this document is to provide the user with the procedures needed to properly assemble and disassemble the 50th percentile male Hybrid III dummy, certify its components and verify its mass and dimensions. Also within this manual are guidelines for handling accelerometers, repairing flesh and setting joints.
Dummy Testing and Equipment Committee
Instrumentation for Impact Test Part 1 - Electronic InstrumentationJ211/1_202208 (Current)8/19/2022
This SAE Recommended Practice outlines a series of performance recommendations, which concern the whole data channel. These recommendations are not subject to any variation and all of them shall be adhered to by any agency conducting tests to this practice. However, the method of demonstrating compliance with the recommendations is flexible and can be adapted to suit the needs of the particular equipment the agency is using. It is not intended that each recommendation be taken in a literal sense, as necessitating a single test to demonstrate that the recommendation is met. Rather, it is intended that any agency proposing to conduct tests to this practice shall be able to demonstrate that if such a single test could be and were carried out, then their equipment would meet the recommendations. This demonstration shall be undertaken on the basis of reasonable deductions from evidence in their possession, such as the results of partial tests. In some systems, it may be necessary to divide the whole channel into subsystems, for calibration and checking purposes. The recommendations have been written only for the whole channel, as this is the sole route by which subsystem performances affect the quality of the output. If it is difficult to measure the whole channel performance, which is usually the case, the test agency may treat the channel as two or more convenient subsystems. The whole channel performance could then be demonstrated on the basis of subsystem results, together with a rationale for combining the subsystem results together. SAE J211-1 of this SAE Recommended Practice covers electronic instrumentation. SAE J211-2 covers photographic instrumentation.
Safety Test Instrumentation Standards Committee
Low Speed Thorax Impact Test Procedure for the HIII5F DummyJ2878_202206 (Current)6/9/2022
This procedure establishes a recommended practice for performing a Low Speed Thorax Impact Test to the Hybrid III Small Female Anthropomorphic Test Device (ATD or crash dummy). This test was created to satisfy the demand by the industry to have a certification test which results in peak chest deflection similar to current full vehicle, frontal impact tests. An inherent problem exists with the current certification procedure because the normal (6.7 m/s) thorax impact test has test results for peak chest deflection that are greater than those currently seen in full vehicle, frontal tests. The intent of this document is to develop a low speed thorax certification procedure for the H-III5F dummy with a 3.0 m/s impact similar to the SAE J2779 procedure for the H-III50M dummy.
Dummy Testing and Equipment Committee
Seatback Strength and Its Effect on In-Position and Out-of-Position ATD Loading in High-Speed Rear Impact Sled Tests2022-01-08563/29/2022
Vehicle rear structure stiffness has increased as a result of the requirements in the FMVSS 301R, which has also corresponded to an increase in front-row seat strength. This study evaluates the structural behavior and occupant response associated with production-level seats equipped with body-mounted D-rings, and very stiff all-belt-to-seat (ABTS) in a group of 12 deceleration sled tests. A double-haversine pulse with approximately 100-msec duration was used for all tests, with peak accelerations of approximately 19 g for the 40 km/h (25 mph) tests and peak accelerations of 28 g for the 56 km/h (35 mph) test. This generic pulse was designed to represent a severe rear impact crash involving vehicles with stiffer rear structures. The tests compared occupant responses and resulting structural deformation of an original equipment manufacturer (OEM) production-level driver seat from a pickup and a very stiff modified ABTS. Both seating systems were equipped with dual recliners. Various combinations of tests evaluated the effects of a rear-end impact principal direction of force (PDOF, 5:30 or 6:00), occupant pre-impact seated position (in-position or out-of-position), latch plate design (single-slotted sliding latch plate or dynamic locking latch plate), and pretensioner deployment strategies (none, anchor, and retractor for the production-level seat and buckle for the modified ABTS seat). The OEM seats showed seatback deformation patterns that were indicative of the load path from occupant engagement and were influenced by a number of test-specific factors. The very stiff ABTS seats did not demonstrate appreciable residual seatback deformation. None of the upper neck metrics exceeded the injury assessment reference values (IARVs) for ATDs in the OEM seats, regardless of the ATD pre-impact posture (IP or OOP). The out-of-position (OOP) anthropomorphic test devices (ATDs) experienced elevated upper neck tension force, extension moment, and neck injury criteria (Nij) compared to the in-position (IP) ATDs in both the production-level and the very stiff ABTS. Dynamic test data show that the yielding seat attenuated both the chest accelerations and head/neck injury metrics, whereas the non-yielding seatback in the very stiff ABTS seat enhanced upper neck injury potential by rapidly decelerating the ATD torso, particularly for the OOP ATD.
Croteau, Jeffrey, Toney-Bolger, Megan, Isaacs, Jessica L., Shurtz, Ben, Zolock, John
Multi-Objective Optimization Study on Ligament Characteristics of Neck Finite Element Model2022-01-08623/29/2022
This paper proposes a new method to improve the fit between the neck finite element calculation results and the experimental data through multi-objective optimization of cervical ligament parameters. By refining a previously established finite element model of the neck and improving the fineness of vertebrae and other structures, a new finite element model of the neck was established. The new model adopts the same material property parameters as the previous model. We performed many simulation calculations, each time only one ligament in the model was removed, leaving other structures unchanged. By observing the changes in the angle of the neck joints in the neck torsion experiment of the model before and after the ligament was removed, the influence of the ligament on the model was obtained. The six ligaments with the largest contribution are selected, and their laxity is optimized for multi-objective research, and the optimal solution for the laxity of the selected ligaments is obtained. The optimized ligament relaxation parameters are applied to the neck model to verify the effectiveness of the Panjabi’s experiment. The calculated joint angle is in good agreement with the experimental data. Furthermore, using the forward flexion and extension motion angles of Nightingale et al. 2007 model to simulate and verify the present model, the calculated value is basically consistent with the experimental value. In order to further verify the effectiveness of the established neck model, the head and neck drop experiment, the front collision and rear collision experiment of the volunteer trolley were used for simulation verification. The results show that the calculated values of head centroid displacement, acceleration, and head rotation angle fit well with the experimental values.
Yang, Shuaijun, Song, Xuewei, Wang, Peng, Wang, Nan
Development of Biomechanical Computational Models of Six-Year-Old Child Occupant with Different Sitting Postures and Application in the Study of Whiplash Injuries2022-01-08693/29/2022
With the development of intelligent cockpit, child occupants will engage in traffic operation in various sitting postures. Therefore, studying the mechanism and risk of whiplash injury of child occupants with different sitting postures has important application value for the research and development of child restraint system. In this study, the 120° and 135° sitting postures of six-year-old child occupant were developed based on the validated 105° sitting posture finite element model with detailed anatomical structure. The whiplash test in Euro NCAP was reconstructed to evaluate the influence of sitting posture angle on the risk of whiplash injury. In the three groups of simulation experiments, the Upper Neck Tension (Fz) was far less than the higher limit of Euro NCAP evaluation although the Fz value increased as the upper torso angle increases. However, the Upper Neck Shear (Fx) and Neck Injury Criterion (NIC) values from the 105° sitting posture exceeded the higher limit of Euro NCAP by 124% and 9%, respectively，increasing the risk of slight neck injury. Neck Protection Criteria (Nkm), NIC, cervical spine stress, and spinal cord stress from 120° sitting posture decreased by 23%, 42%, 56.9%, and 41.1%, respectively, compared with those parameters from the child standard sitting posture (105°). However, the Fx value from 120° sitting posture exceeded the higher limit by 101%; a slight risk of neck injury thus still exists. These assessment parameters from 135° sitting posture decreased by 60%, 50%, 77.6% and 43.6%, respectively, and the parameters were all lower than the higher limit of Euro NCAP. In addition, the maximum von Mises stress was mainly concentrated at the contact position between atlas and axial odontoid (105° and 120° postures) and the posterior arch of atlas with axial odontoid (135° postures). In conclusion, the risk of whiplash injury decreased with the increase of upper torso angle.
Li, Haiyan, Wang, Yanxin, He, Lijuan, Lv, Wenle, Cui, Shihai, Ruan, Jesse Shijie
Biomechanical Responses of the THOR-AV ATD in Rear Facing Test Conditions2022-01-08363/29/2022
The THOR-AV dummy is a modified THOR dummy being developed for occupant safety testing in upright and reclined seating postures. The dummy has a new neck with improved biofidelity in rear impact, a pelvis/abdomen/lumbar design to improve seating posture, and a pelvis anthropometry that mimics human submarining responses for reclined seat testing. The dummy was evaluated against postmortem human subject (PMHS) corridors in rearward facing impact conditions (56 km/h impact speed, 38g acceleration) in both 25° and 45° seatback configurations. Biofidelity Ranking System (BRS) scores were calculated in accordance with NHTSA’s latest calculation algorithm. The BRS scores for THOR-AV seat loading are 1.58 (“good” biofidelity) and 2.94 (“marginal” biofidelity) for the 25° and 45° configurations respectively. The BRS scores for THOR-AV occupant responses are 1.95 and 1.38 for the 25° and 45° configurations respectively, both corresponding to “good” biofidelity. From the evaluation, the dummy motion in the vertical direction is lacking compared to PMHS responses. The dummy durability is promising, with no damage observed in the test series.
Wang, Zhenwen Jerry
The Role of Three-Point Restraints for Occupants in Moderate Severity Frontal Collisions2022-01-08453/29/2022
Field accident data and vehicle crash and sled testing indicate that occupant kinematics, loading, and associated injury risk generally increase with crash severity. Further, these data demonstrate that the use of restraints, such as three-point belts, provides mitigation of kinematics and reduction in loading and injury potential. This study evaluated the role of seat belts in controlling occupant kinematics and reducing occupant loading in moderate severity frontal collisions. Frontal tests with belted and unbelted anthropomorphic test devices (ATDs) in the driver and right front passenger seats were performed at velocity changes (delta-Vs) of approximately 19 kph (12 mph) and 32 kph (20 mph) without airbag deployment. At the lower-moderate severity (19 kph), motion of the belted ATDs was primarily arrested by seat belt engagement, while motion of the unbelted ATDs was primarily arrested by interaction with forward vehicle structures. Occupant loading and injury risk was generally lower with proper belt use as compared to an unbelted occupant. At the higher-moderate severity (32 kph), both the belted and unbelted ATDs demonstrated lower extremity engagement with forward vehicle structures, though femur compression loads were substantially attenuated for the belted ATDs. With belt use, the pelvis and torso were restrained by the seat belt which reduced overall forward torso and head excursion. As the neck flexed due to torso restraint, increased lower neck flexion was observed relative to the unbelted ATDs, though upper neck flexion remained greater for the unbelted ATD. In the higher-moderate severity test, neck flexion about the torso restraint resulted in the belted driver ATD’s head contacting the steering wheel. The unbelted ATDs moved forward in an unrestrained fashion until motion was arrested via contact with forward vehicle structures, resulting in generally higher occupant loading in comparison to their belted counterparts. These findings support the effectiveness of seat belts in controlling occupant kinematics and reducing injury potential in moderate severity frontal collisions.
Isaacs, Jessica L., George, Juff, Campolettano, Eamon, Cutcliffe, Hattie, Miller, Bruce
Human Head and Neck Kinematics during Autonomous and Human Braking in Three Initial Head Positions09-10-02-00073/28/2022
Whiplash injuries resulting from vehicle collisions are still a significant socio-economic issue across the world. Years of research has resulted in the development of injury criteria, restraint systems and a deeper understanding of the injury mechanism. However, some grey areas remain and, in the context of the increasing automation of vehicles, one can wonder how the injury mechanisms may change due to changes in collision forces or directions. This article presents an experiment with ten volunteers subjected to two braking modes, including automated braking preceded by an alarm warning or robot human braking, in three different initial head positions: forward facing, lateral rotation and flexion rotation. The volunteers were equipped with inertial measurement units to record their head and neck dynamics. Results show that the initial position of volunteers implies differences in the volunteer head dynamics. Also, the auditory alarm emitted prior to the emergency braking may have helped the volunteers to mitigate the mechanical stimulus and most likely the injury risk.
Mackenzie, Jamie, Dutschke, Jeffrey, Di Loreto, Cédric, Forrest, Matthew, Van Den Berg, Andrew, Merienne, Frédéric, Chardonnet, Jean-Rémy, Sandoz, Baptiste
Muscle Activation Affects Kinematic Response and Injury Risk in Non-Traditional Oblique Impact Scenarios Assessed with a Head and Neck Finite Element Model09-10-02-00083/23/2022
Detailed finite element human body models (HBMs), and neck models (NMs) in particular, have been used to assess response and injury risk with a focus on frontal, lateral, and rear impact conditions. Although HBMs have successfully predicted kinematics and the importance of active muscle in simple loading conditions, they have generally not been assessed for more complex loading conditions such as non-traditional oblique loading that may be encountered in future vehicles equipped with automated driving systems. In this study, a contemporary NM was assessed using oblique human volunteer sled test data. Average head and first thoracic vertebra kinematics were determined from the volunteer tests and applied as a boundary condition to the NM. An open-loop co-contraction muscle activation scheme with four activations times within reported human limits (50, 75, 100, no activation) was used to investigate the effect on response and potential for injury risk. The T1 and head kinematics from 45 oblique impact volunteer tests were analyzed in five groups according to the peak sled acceleration (4g to 11g), resulting in mean and standard deviation corridors. The NM ran stably to completion for all impact cases, demonstrating complex forward excursion of the head, and lateral bending and axial rotation of the neck under oblique loading. Objective evaluation of the predicted head kinematics over a range of impact severities demonstrated fair to good biofidelity (0.65 to 0.77 rating) for the 75 ms activation time and no tissue damage was identified, in agreement with the experimental tests. The model correlation was higher for the 50 ms activation time, suggesting that the volunteer muscle activation times were lower than the average for the population. The average 75 ms co-contraction activation has previously provided good results in frontal and lateral impacts and, in the current study, demonstrated applicability to more complex oblique impact scenarios that may be encountered in ADS-equipped vehicles.
Barker, Jeffrey, Cronin, Duane S.
Robotic Neck Brace Can Help Analyze the Impact of Cancer TreatmentTBMG-4002910/1/2021
A new robotic neck brace from researchers at Columbia Engineering and their colleagues at Columbia’s department of otolaryngology may help doctors analyze the impact of cancer treatments on the neck mobility of patients and guide their recovery.
Reconstruction of an Auto-Rickshaw Frontal Crash using FE Simulation with Validation using Captured Crash Video from India2021-28-025710/1/2021
The three-wheeled "Auto-Rickshaws" [Auto] plays a significant role in road transportation, especially in India. The crash safety and reconstruction studies have been widely used in four-wheelers, whereas the availability of such data for Auto was limited. In recent times, accident data processing from available videos is being utilized to observe the crash scenario. The crash parameters can be given as inputs to the crash analysis. This paper focuses on the process the real-world accident data and study crash characteristics. With limitation in the availability of detailed injuries post-crash, the study was restricted to reconstructing crash kinematics and estimating indicative injuries to the driver. The source of video data is videos of crash available in public domains like YouTube. PYTHON video processing tool has been used to process the set of real-world accident video data. Object detection, Pixel per meter computation and object tracking are the significant steps to process the accident data, from which the collision speed is obtained. The auto-rickshaw CAE model and driver dummy (Adult male 50 percentile) were used in LS DYNA to conduct crash analysis at obtained collision speed. The reconstructed crash with matching kinematics showed that the driver experienced a noticeable amount of impact forces near the neck joint and knees. This methodology is proposed as a step in the direction of understanding occupant safety in auto rickshaws.
S, Ragul, Sankarasubramanian, Hariharan, Kondaveeti, N S V Nikas, Yadav, Pandugayala Nithin
Applicability of Neck Injury Criteria Critical Intercepts for Human Body Finite Element Models09-09-02-00088/25/2021
The critical intercepts used for the Neck Injury Criterion (Nij) have not been assessed in computational human body models. Under matched-pair conditions, the response of the head-neck complex was compared between the Livermore Software Technology Corporation (LSTC) Hybrid III (HIII) and Global Human Body Models Consortium’s (GHBMC) 50th percentile, detailed male occupant (M50-O) models. The head and neck of the M50-O and HIII were subjected to the dummy performance calibration test procedure for flexion and extension. As a nominal condition, the HIII model met all calibration specifications. Operationalization of the M50-O’s initial position was defined by equivalent head CG location to the HIII and subsequently compared at nominal, ±10%, ±20%, and ±30% of pendulum displacement. Kinematics of the head CG, forces and moments of the upper neck, and changes in neck angle were post processed and compared between the models. The sagittal velocity of the head CG was found to be greater for the M50-O in flexion and for the HIII in extension. Coupled with this trend, greater force and moment exhibited a direct, positive correlation with maximum, sagittal head CG velocity. Correlates of force and moment between the models in both flexion and extension have been derived from the results of this work. As an extension of this finding, modified intercepts of the Nij for application to the M50-O were plotted. These human model-specific critical intercept values may be understood as a consequence of the natural lordosis exhibited by the cervical spine of the M50-O, a feature absent in the HIII. The correlates and conclusions of this work are limited to the range of induced forces and moments, as well as loading rate. Future work will seek to compare the response of the HIII and M50-O models in combined compression-flexion and compression-extension loading.
Johnson, Dale, Devane, Karan, Koya, Bharath, Gayzik, F. Scott
Assessment of Acclimation of 5th Percentile Female and 50th Percentile Male Volunteer Kinematics in Low-Speed Frontal and Frontal-Oblique Sled Tests09-09-01-00015/12/2021
In order to accurately represent the response of live occupants during pre-crash events and frontal crashes, computational human body models (HBMs) that incorporate active musculature must be validated with appropriate volunteer data that represents a wide range of demographic groups and potential crash conditions. The purpose of this study was to quantify and compare occupant kinematic responses for unaware (relaxed) small female and midsize male volunteers during low-speed frontal and frontal-oblique sled tests across multiple test conditions, while recognizing, assessing, and accounting for potential acclimation effects due to multiple exposures. Six 5th percentile female and six 50th percentile male volunteers were exposed to multiple low-speed frontal and frontal-oblique sled tests on two separate test days. Volunteers experienced one test orientation and two pulse severities (1 g and 2.5 g) on each test day. A Vicon motion capture system was used to quantify the three-dimensional (3D) kinematics of the volunteers. Peak forward excursions of select body locations were compared within a test day and between test days for the same test condition to determine if and how acclimation occurred. Differences between demographic groups were also compared after accounting for any observed acclimation. Acclimation was not observed within a test day but was observed between test days for some demographic groups and some test conditions. In general, head, neck, and shoulder responses were affected, but the elbow, hip, and knee responses were not. Males generally moved farther forward compared to females during the frontal tests, but both groups moved forward similarly during the frontal-oblique tests. Overall, this study provides new female and male biomechanical data that can be used to further develop and validate HBMs that incorporate active musculature in order to better understand and assess occupant response and injury risk in pre-crash events and frontal crashes.
Chan, Hana, Albert, Devon L., Gayzik, F. Scott, Kemper, Andrew R.
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