50th Percentile Male Research Articles

Influence of the surrounding environment on the response of seated midsize male volunteers subjected to lateral sled accelerations

Predicting vehicle occupants’ posture during evasive manoeuvres is crucial for assessing their safety in the event of a collision. Volunteer experiments have been performed in the past under lateral accelerations, both within a vehicle cabin and on a seat mounted on a sled. However, discrepancies in the volunteer responses between both setups have been identified. This study hypothesizes that the response of the volunteers differs as a consequence of the proximity to the frame in the vehicle cabin, in comparison to the absence of such a structure on the sled.The present study conducted a novel sled experiment, on which five volunteers with anthropometry comparable to the 50th percentile male were subjected to 0.3 g lateral accelerations, with three different surrounding environments. In twelve pulses, an additional lateral structure was placed to the right or left side of the seated volunteers. The volunteers were asked to either brace or relax their muscles.The results show significant differences between the configurations with and without the structure placed on the right side. This effect was observed for both the lateral excursion of the upper body and the corresponding rotation when the volunteers were relaxed (p < 0.01). The average maximum lateral head rotation decreased from 27° to 14° with the structure on the right. No significant difference in head rotation was found for the braced muscle configuration.This study supports the hypothesis that the proximity to a surrounding environment influences human responses during dynamic loading. Nevertheless, there was no significant difference in maximum muscle activation between the configurations, but a faster reaction of the sternocleidomastoid muscle with the presence of the structure.

A comparison of fracture response in female and male lumbar spine in simulated under body blast component tests

Underbody blasts (UBB) from mines and improvised explosive devices in military combat can cause debilitating spine injuries to vehicle mounted soldiers. Due to the exclusion of females in combat roles in prior US Department of Defense policy, UBB exposure and injury have predominantly affected male soldiers. Recent policy changes have opened many combat roles to women serving in the US Military (Carter, 2015) and have increased the need to understand the injury potential for female Warfighters. The goal of this study was to investigate the fracture response of adult female lumbar spines compared to adult male spines in UBB relevant loading to identify potential differences in either fracture mechanism or force. Results are presented for 15 simulated UBB spine compression tests using three small female (SF), five large female (LF), and seven mid-sized male (MM) post-mortem human subjects (PMHS). These PMHS groups align to 5th- and 75th-percentile female and 50th-percentile males, based on height and weight from the 2012 Anthropometric Survey of U.S. Army Personnel (Gordon et al., 2014). Both small females and large females (similar in size to the males) were included to assess the role of size and/or sex in the response. Tests were conducted at Virginia Tech on a cam-driven linear compression rig, which included a 6-axis load cell and ram accelerometer to evaluate the fracture. Fracture was visualized through high-speed x-ray video. All female and male spines exhibited similar fracture initiation at the end plates and progression through the vertebral body. The resulting severe compression and burst fractures were representative of reported theatre injuries (Freedman et al., 2014). Mean axial fracture forces were −4182 ± 940 N (SF), −6225 ± 1180 N (LF), −5459 ± 1472 N (All Females) and −7993 ± 2445 N (MM). The SF group was found to have statistically significant differences in mean fracture force compared to both LF and MM groups, while no significant difference was found between LF and MM groups, although the mean force at initial fracture was lower for the LF group. The All-Females group Fz mean was significantly different from the MM group. These data suggest that the significant difference in weight between the SF and LF groups, did have an influence on the Fz outcome, when controlling for sex. Conversely, controlling for size in the LF and MM comparison, sex did influence the mean Fz, but was not statistically significant. Groups with combined sex and size differences, however, did show significant differences in mean Fz. Further study is warranted to understand whether sex or size has a larger effect on fracture force. Mean ram displacement (spine compression) values at fracture initiation were −6.0 ± 5.3 mm (SF), −4.4 ± 0.8 mm (LF), −5.0 ± 3.0 mm (All Females), −6.2 ± 4.5 mm (MM). Spine compression did not seem to be largely influenced by either sex or size, and none of the groups was found to have significant differences in mean displacement values.

A modified finite element dummy model of Chinese adult male used for train collision simulations

ABSTRACT This work established a modified finite element (FE) dummy model representing the Chinese 50th percentile males through the whole segment scaling method, referring to the Total Human Model for Safety (THUMS-AM50) of European and American 50th percentile males. The head, neck, chest, abdomen, and knee-thigh-hip (KTH) of the modified model were validated, respectively, by the cadaver experimental results. Integrating the dummy models with a four-car marshalling train collision FE model, we analysed the dynamic response in terms of human body posture, head, and neck injuries of the Chinese 50th percentile males and the European and American 50th percentile males during the frontal train collision process. The corresponding simulation results fitted well with the experimental tests, indicating that the established modified model exerted great biological fidelity. Compared with European-American 50th percentile males, the Von-Mises stress, shear stress, maximum principal strain (MPS), and the cumulative strain damage measure CSDM0.15 of the brain in the Chinese 50th percentile males were approximately higher by 22.21%, 19.85%, 36.58%, and 47.55%, respectively. That meant the Chinese males might be at a higher risk of brain contusion and diffuse axonal injury (DAI) during the train collision. Meanwhile, the Chinese 50th percentile males had more severe neck extension, especially the maximum cervical vertebrae Von-Mises stress and neck injury predictor (Nij) were increased by 30.3% and 50%, respectively. The established modified model could provide a more accurate simulation for predicting the Chinese body injury response during the train collision.

Lower Extremity Impact and Injury Responses of Male and Female PMHS to High-Rate Vertical Loading.

Whole-body PMHS (Post Mortem Human Surrogate) testing was conducted on the Accelerative Loading Fixture (ALF), which is designed to generate floor and seat loading conditions at the level, rate, location, direction, and extent seen in UBB (Underbody Blast). The overarching goal of this research effort was to examine potential differences in the lower extremity response of females and males under UBB conditions. The ALF consists of an occupant platform that is driven upward by the detonation of an explosive charge. The floor plate undergoes plastic deformation. The occupant platform supports two rigid seats for surrogates. Twenty un-embalmed PMHS were tested, including 50th-percentile males, 75th-percentile females, and 5th-percentile females. Two test series were conducted. Series A had a target floor speed of 8 m/s (2-ms time-to-peak) with a target seat speed of 5 m/s (4-ms time-to-peak). Series B had a target floor speed of 20 m/s (2-ms time-to-peak) with a target seat speed of 4 m/s (7-ms time-to-peak). Major damage occurred to the femur, tibia, fibula, talus, and calcaneus. Lower extremity damage type, incidence, and extent varied between the two sexes. Fifty-percent probability of calcaneus fracture for less than 3-ms time-to-peak is associated with a 781-g peak tibia vertical acceleration for 50th-percentile males, 650-g for 75th-percentile females, and 396-g for 5th-percentile females. Fifty-percent probability of calcaneus fracture, regardless of time-to-peak, is associated with a 368-g peak femur vertical acceleration for 50th-percentile males, 332-g for 75th-percentile females, and 218-g for 5th-percentile females. These results show differences in kinematics and damage outcome between female and male PMHS in UBB conditions. These findings will inform future decisions regarding the requirements for test capabilities that incorporate the female Warfighter. Ultimately, advancements can be made in injury assessment tools such as improved physical surrogates, injury assessment and prediction criteria, modeling and simulation capabilities, test methods, and the optimization of military ground vehicles, personal protective equipment, and injury countermeasures.

Experimental and modelling research on coach passengers’ safety in frontal impacts

Road traffic accidents involving coaches do not happen very often, but they are very dangerous because they affect a large number of passengers. Coaches (or intercity buses) are not equipped with safety belt harnesses. Valid regulations do not impose any obligation on coach manufacturers to provide intercity buses with either two- or three-point safety belts. This fact may result from the unawareness of risks and injuries that might befall the passengers with no safety belts during accidents. That is the reason why this work aims to compare the aftermath of coach accidents with no safety belts and the ones with safety belts. A detailed aim of this research is to analyse the results of dynamic loads during a frontal impact exerted on coach passengers travelling with and without (two- and three-point) safety belts. This objective was achieved by performing experimental studies and modelling which focused on the process of dynamic load transfer on the human body during a traffic accident. The research was conducted parallel on an adult and a child. The equivalent of a 50th percentile male was a hybrid III dummy (M50), whereas a child at the age of about 10 was represented by a P10 dummy. A numerical model was generated and verified in experimental testing in the scope of kinematics. Also, the comparison of the recorded courses of forces, acceleration, and moments was conducted. The results obtained from the tests were analyzed regarding the injury criteria for head, neck, and thorax. It was observed that both for the two-point safety system and the lack of safety belts, there were high values of acceleration recorded in the centre of gravity of the head. On the basis of the investigations conducted, it was ascertained that only a three-point safety belt system ensures the satisfaction of all injury criteria within admissible standards both in the case of criteria defined in the rules no. 80 and the rules no. 94 determined by the United Nations Economic Commission for Europe. It is the three-point safety belt system which should be obligatory in all intercity buses.

Development and evaluation of advanced seat and helmet for safer motorcycle users

The purpose of this research is to develop the prototypes of advanced motorcycle seat and protective equipment of compulsory helmet wearing through experimental evaluation. In this prototype, suitable sensors for detecting pillion, strapping chin and wearing helmet of motorcycle users are integrated with the existing motorcycle and helmet. These sensors were developed and investigated through the experimental testing procedures. For the evaluation of pillion seat sensor, the hip of dummy hybrid III 50th percentile male was used with the discrete values of mass on the sliding machine at each position of pillion seat. To conduct the experimental evaluation of strapping chin and wearing helmet conditions, the EN960 european standard headform were used at each position. Consequently, the functional detective range of the developed prototypes are identified and specified at pillion seat, chin strap and helmet wearing conditions. Additionally, these results are planned to develop an advanced system for supporting motorcycle users and increasing awareness of injury reduction.

Nonlinear multibody dynamics and finite element modeling of occupant response: part II—frontal and lateral vehicle collisions

Due to the increased number of fatalities and injuries in motor vehicle accidents, it is crucial to study the kinematic and kinetic occupant response during collisions, specifically the head and neck response due to their vulnerable nature. In Part I we have addressed rear end collisions. In Part II we examine occupant response in frontal and lateral collisions. Two multibody dynamics models of the cervical spine of the 50th percentile male were developed and validated. The cervical spine was modeled as a series of rigid links connected through single and two degrees of freedom viscoelastic joints. In addition, finite element simulations of two compact sedan vehicle were conducted to capture realistic crash acceleration of the driver seat in frontal and lateral collision scenarios. Furthermore, finite element simulations were performed to capture the kinematic and kinetic response of a seated restrained male occupant subjected to the realistic seat accelerations in frontal and lateral collisions. Finally, the possibility of injury in frontal, lateral and rear collisions was evaluated. The evaluation of ligament injury risk shows high risk of injury at the interspinous ligament in frontal collision, at the anterior longitudinal ligament in rear collision and at the near-side capsular ligament in lateral collision. The highest vertebral fracture risks were found at the mid- and lower cervical spine in rear and lateral collisions. The outcomes of this work provide a better understanding of occupant injury mechanism during frontal, lateral and rear collisions which is essential to enhancing motor vehicle safety.

Nonlinear multibody dynamics and finite element modeling of occupant response: part I—rear vehicle collision

With the rise in vehicle ownership, the need to reduce the risk of injury among vehicle occupants that arises from vehicle collisions is important to occupants, insurers, manufacturers and policy makers alike. The human head and neck are of special interest, due to their vulnerable nature and the severity of potential injury in these collisions. This work is divided into two parts: In Part I, we focus our attention to modeling rear collision that could lead to whiplash. Specifically, two multibody dynamics (MBD) models of the cervical spine of the 50th percentile male are developed using realistic geometries, accelerations and biofidelic variable intervertebral rotational stiffness. Furthermore, nonlinear finite element (FE) simulations of two generic compact sedan vehicles in rear collision scenario were performed. Using the acceleration profiles measured at the driver’s seat of the colliding vehicles, FE simulation of a seated and restrained occupant in rear collision was performed to determine the occupant response. The resultant accelerations, measured at the T1 vertebra of the occupant model, were used as an input to the MBD models to obtain their kinematic response. Validation of the MBD models shows great agreement with experimentally published data. Comparison between the MBD and FE simulations for a 32 km/h vehicle-to-vehicle impact shows similar trends in head trajectory. However, the MBD models reported less peak head displacements compared to the FE model. This is attributed to the failure of the anterior longitudinal ligament at the mid cervical spine leading to increased intervertebral rotation in the FE model.

Quantification of Skeletal and Soft Tissue Contributions to Thoracic Response in a Dynamic Frontal Loading Scenario.

Thoracic injuries continue to be a major health concern in motor vehicle crashes. Previous thoracic research has focused on 50th percentile males and utilized scaling techniques to apply results to different demographics. Individual rib testing offers the advantage of capturing demographic differences; however, understanding of rib properties in the context of the intact thorax is lacking. Therefore, the objective of this study was to obtain the data necessary to develop a transfer function between individual rib and thoracic response. A series of non-injurious frontal impacts were conducted on six PMHS, creating a loading environment commensurate to previously published individual rib testing. Each PMHS was tested in four tissue states: intact, intact with upper limbs removed, denuded, and eviscerated. Following eviscerated thoracic testing, eight individual mid-level ribs from each PMHS were removed and loaded to failure. A simplified model in which ribs of each thorax are treated as parallel springs was utilized to evaluate the ability of individual rib response data to predict each subject's eviscerated thoracic response. On average across subjects, denuded thoraces retained 89% and eviscerated thoraces retained 46% of intact force. Similarly, denuded thoraces retained 70% and eviscerated thoraces retained 30% of intact stiffness. The rib model did not adequately predict eviscerated thoracic response but provided a better understanding of the influence of connective tissue on a rib's behavior with-in the thorax. Results of this study could be used in conjunction with the database of individual rib test results to improve thoracic response targets and help assess biofidelity of current anthropomorphic test devices.

DEVELOPMENT AND BIOFIDELITY EVALUATION OF AN OCCUPANT BIOMECHANICAL MODEL OF A CHINESE 50TH PERCENTILE MALE FOR SIDE IMPACT

Finite element modeling has played a significant role in the study of human body biomechanical responses and injury mechanisms during vehicle impacts. However, there are very few reports on similar studies conducted in China for the Chinese population. In this study, a high-precision human body finite element model of the Chinese 50th percentile male was developed. The anatomical structures and mechanical characteristics of real human body were replicated as precise as possible. In order to analyze the model’s biofidelity in side-impact injury prediction, a global technical standard, ISO/TR 9790, was used that specifically assesses the lateral impact biofidelity of anthropomorphic test devices (ATDs) and computational models. A series of model simulations, focusing on different body parts, were carried out against the tests outlined in ISO/TR 9790. Then, the biofidelity ratings of the full human body model and different body parts were evaluated using the ISO/TR 9790 rating method. In a 0–10 rating scale, the resulting rating for the full human body model developed is 8.57, which means a good biofidelity. As to different body parts, the biofidelity ratings of the head and shoulder are excellent, while those of the neck, thorax, abdomen and pelvis are good. The resulting ratings indicate that the human body model developed in this study is capable of investigating the side-impact responses of and injuries to occupants’ different body parts. In addition, the rating of the model was compared with those of the other human body finite element models and several side-impact dummy models. This allows us to assess the robustness of our model and to identify necessary improvements.

Comparison of the THOR and Hybrid III Responses in Oblique Impacts

NHTSA has been investigating a new test mode in which a research moving deformable barrier (RMDB) impacts a stationary vehicle at 90.1 kph, a 15 degree angle, and a 35% vehicle overlap. The test utilizes the THOR NT with modification kit (THOR) dummy positioned in both the driver and passenger seats. This paper compares the behavior of the THOR and Hybrid III dummies during this oblique research test mode. A series of four full vehicle oblique impact crash tests were performed. Two tests were equipped with THOR dummies and two tests were equipped with Hybrid III dummies. All dummies represent 50th percentile males and were positioned in the vehicle according to the FMVSS208 procedure. The Hybrid III dummies were instrumented with the Nine Accelerometer Package (NAP) to calculate brain injury criteria (BrIC) as well as THOR-Lx lower legs. Injury responses were recorded for each dummy during the event. High speed cameras were used to capture vehicle and dummy kinematics. The vehicle restraint devices and their associated deployment times remained the same for each test. Post test analysis investigated each dummy injury response, kinematics, and vehicle structural performance. The results of the current study show that during an oblique impact, where significant lateral motion of the vehicle is observed, there are differences between the THOR and Hybrid III dummies. Language: en

Biomechanical and Injury Response of Human Foot and Ankle Under Complex Loading

Ankle and subtalar joint injuries of vehicle front seat occupants are frequently recorded during frontal and offset vehicle crashes. A few injury criteria for foot and ankle were proposed in the past; however, they addressed only certain injury mechanisms or impact loadings. The main goal of this study was to investigate numerically the tolerance of foot and ankle under complex loading which may appear during automotive crashes. A previously developed and preliminarily validated foot and leg finite element (FE) model of a 50th percentile male was employed in this study. The model was further validated against postmortem human subjects (PMHS) data in various loading conditions that generates the bony fractures and ligament failures in ankle and subtalar regions observed in traffic accidents. Then, the foot and leg model were subjected to complex loading simulated as combinations of axial, dorsiflexion, and inversion loadings. An injury surface was fitted through the points corresponding to the parameters recorded at the time of failure in the FE simulations. The compelling injury predictions of the injury surface in two crash simulations may recommend its application for interpreting the test data recorded by anthropometric test devices (ATD) during crash tests. It is believed that the methodology presented in this study may be appropriate for the development of injury criteria under complex loadings corresponding to other body regions as well.

A Finite Element Model of the Lower Limb for Simulating Automotive Impacts

A finite element (FE) model of a vehicle occupant's lower limb was developed in this study to improve understanding of injury mechanisms during traffic crashes. The reconstructed geometry of a male volunteer close to the anthropometry of a 50th percentile male was meshed using mostly hexahedral and quadrilateral elements to enhance the computational efficiency of the model. The material and structural properties were selected based on a synthesis of current knowledge of the constitutive models for each tissue. The models of the femur, tibia, and leg were validated against Post-Mortem Human Surrogate (PMHS) data in various loading conditions which generates the bone fractures observed in traffic accidents. The model was then used to investigate the tolerances of femur and tibia under axial compression and bending. It was shown that the bending moment induced by the axial force reduced the bone tolerance significantly more under posterior-anterior (PA) loading than under anterior-posterior (AP) loading. It is believed that the current lower limb models could be used in defining advanced injury criteria of the lower limb and in various applications as an alternative to physical testing, which may require complex setups and high cost.

Motion of the Head and Neck of Female and Male Volunteers in Rear Impact Car-to-Car Impacts

Objectives: The objectives of this study were to quantify and compare dynamic motion responses between 50th percentile female and male volunteers in rear impact tests. These data are fundamental for developing future occupant models for crash safety development and assessment. Methods: High-speed video data from a rear impact test series with 21 male and 21 female volunteers at 4 and 8 km/h, originally presented in Siegmund et al. (1997), were used for further analysis. Data from a subset of female volunteers, 12 at 4 km/h and 9 at 8 km/h, were extracted from the original data set to represent the 50th percentile female. Their average height was 163 cm and their average weight was 62 kg. Among the male volunteers, 11 were selected, with an average height of 175 cm and an average weight of 73 kg, to represent the 50th percentile male. Response corridors were generated for the horizontal and angular displacements of the head, T1 (first thoracic vertebra), and the head relative to T1. T-tests were performed with the statistical significance level of .05 to quantify the significance of the differences in parameter values for the males and females. Results: Several differences were found in the average motion response of the male and female volunteers at 4 and 8 km/h. Generally, females had smaller rearward horizontal and angular motions of the head and T1 compared to the males. This was mainly due to shorter initial head-to–head restraint distance and earlier head-to–head restraint contact for the females. At 8 km/h, the female volunteers showed 12 percent lower horizontal peak rearward head displacement (P = .018); 22 percent lower horizontal peak rearward head relative to T1 displacement (P = .018); and 30 percent lower peak head extension angle (P = .001). The females also had more pronounced rebound motion. Conclusions: This study indicates that there may be characteristic differences in the head–neck motion response between 50th percentile males and females in rear impacts. The exclusive use of 50th percentile male rear impact dummies may thus limit the assessment and development of whiplash prevention systems that adequately protect both male and female occupants. The results of this study could be used in the development and evaluation of a mechanical and/or computational average-sized female dummy model for rear impact safety assessment. These models are used in the development and evaluation of protective systems. It would be of interest to make further studies into seat configurations featuring a greater head-to–head restraint distance.

Computer Input Devices — Race and Gender: Is there a mismatch between anthropometry and input device design

Studies have shown an association between intensive computer use and the onset and development of upper extremity musculoskeletal disorders. However, the evidence for possible health effects related to computer input device design and operator anthropometry is limited. The aim of this study was to systematically examine relationships between the current sizing of computer input devices and key anthropometric differences, based on gender and race, in adult computer users. Computer input devices appear to be designed based on anthropometric clearance issues to accommodate the largest users (95th percentile Western males). Based on this current design, less than 6.1% of the worldwide population would “fit” the current pointing device and keyboard design standards. Finger mass is a critical component for determining device activation forces When comparing male and female hand anthropometry, finger mass accounted for the largest anthropometric difference with the 50th percentile females' hand only 73% the mass of the 50th percentile males‘. With respect to similarities, in virtually every aspect of seated workstation anthropometry (i.e. furniture requirements), the 50th percentile Western female very closely approximated the 50th percentile Asian male. The findings of this study indicate that gender and race base differences in workstation design are small relative to the differences in input device activation forces based on hand anthropometry. It appears that the current “one size fits all” paradigm used to design computer input devices may not be optimal. Smaller devices with lower activation forces could benefit a large percentage of the world population.

Finite element evaluation of out-of-position failure modes of the knee-thigh-hip complex in frontal car crashes

Safety has been increased for the upper region of the body, such as head and thorax with the introduction of airbags; however, the percentage of injuries to the lower extremities in car crashes has increased. Though lower extremity injuries are usually not life threatening, they can have long lasting physical and psychosocial consequences. A validated knee-thigh-hip (KTH) finite element (FE) model of a 50th percentile male was used to investigate injury mechanisms during frontal car crashes at different occupant positions. An initial muscle force was activated to achieve different lower limb movements starting from an initial seated position. Simulations of frontal impacts were then performed with the KTH joints at different angles of thigh flexion, adduction and abduction. Failure mechanisms from simulations were compared to results found in the literature to ensure the model provides a useful tool for predicting fractures in the lower limb resulting from out-of-position frontal vehicle crashes.

Development of a finite element model of the knee-thigh-hip of a 50th percentile male including ligaments and muscles

An LSDYNA finite element model of the knee-thigh-hip (KTH) of a 50th percentile male was developed for exploring mechanics of injuries to the KTH during frontal crashes. This includes a model of the geometry of bones and also discrete element representations of ligaments and muscles of the KTH. The model was validated using physical tests obtained from the National Highway Traffic and Safety Administration's (NHTSA) test database. Validation of individual components like the upper femur, femoral condyles and pelvis were performed and compared to similar physical tests. The results were used to verify geometry, material properties and failure mechanisms of bone materials. Validations were also performed against a whole-body cadaver test to verify contributions of passive muscle and ligament forces. Failure mechanisms in the tests and simulations were compared to ensure the model provides a useful tool for exploring fractures in the KTH resulting from frontal vehicle crashes.

Biomechanics of Volunteers Subject to Loading by a Motorized Shoulder Belt Tensioner

A biomechanical study using human volunteers. Motorized shoulder belt tensioning is a new seatbelt technology that is likely to be incorporated into future vehicles. The objective of this study was to characterize the upper torso biomechanics of 3 sizes of adult volunteers (5th percentile female, 50th percentile male, and 95th percentile male) subjected to motorized shoulder belt tensioning in the static environment. There is a lack of volunteer data concerning the biomechanics of occupants subject to motorized precrash shoulder belt tensioning. Studies of torso repositioning by the air force for ejection seats are much too aggressive to be relevant to motorized systems. Low-level motorized shoulder belt tensioning is well tolerated by vehicle occupants but optimized performance by occupant size is unknown. Nineteen male and 6 female subjects were instrumented in a fixture designed to support the occupant leaning forward and apply seatbelt tension. The subjects were 5th percentile females, 50th percentile males, and 95th percentile males. Reflective markers were placed on the subjects to monitor torso kinematics during tensioning. Changes in spinal curvature were small during shoulder belt tensioning and the angular motion of the torso originated within 4.2 cm of the pelvis-femur junction or H-point. Torso repositioning and retraction timing was found to be: 54.3 degrees in 0.78 seconds for the 5th percentile female, 57.6 degrees in 0.95 seconds for the 50th percentile male, and 42.2 degrees in 0.92 seconds for the 95th percentile male. Occupant size has a significant effect on retraction time to reposition the torso during shoulder belt tensioning. Larger vehicle occupants require more time because of a slower retraction velocity. The results are sufficiently simple that a lumped-mass model can predict tensioning kinetics.

Far-Side Occupant Kinematics in Low Speed Lateral Sled

Objective. The objective of this study was to evaluate the far-side occupant kinematics in low-speed lateral pulses with and without a seatbelt system. Methods. The kinematics responses of three volunteers and a Hybrid III were compared in three low-to-moderate lateral pulses. The parameters evaluated were pulses and belt usage. A total of 24 tests were carried out in a side-impact sled. The subjects consisted of two 50th-percentile males (Vol 1 & 2), one 5th-percentile female (Vol 3), and a Hybrid III 50th-percentile male (ATD). All subjects were seated in a far-side impact. Three low speed pulses were used: Pulse 1: a 4 g at 6 km/h, Pulse 2: 4 g/8 kph followed by a -2.5 g pulse to simulate a low curb impact, and Pulse 3: a 4 g's pulse at 10 km/h. In addition, the kinematics result from Pulse 2 was used to assess the performance of a human model. The human model was developed by TNO. Results. For all three pulses, the peak head lateral displacement was greater with the 5th female (Vol 3) than the male volunteers. The ATD results in the 6 and 10 km/h pulses were comparable to the volunteers. However, in Pulse 2, the ATD motion was higher than the volunteers. Conclusion. The results obtained in this study suggest the Hybrid III is a somewhat conservative device for an evaluation of occupant kinematics in low-speed lateral pulses. The human model also seemed to be representative of volunteer kinematics.

Volunteer and Dummy Head Kinematics in Low-Speed Lateral Sled Tests

Understanding human head kinematics prior to the safety countermeasure activation is important to help minimize potential for injury in side impact and rollover situations. The objective of this study was to compare three volunteers and the Hybrid III responses in three low-to-moderate lateral crash pulses. The parameters evaluated were lateral pulses and belt usage. A total of 24 tests were carried out in a side impact sled. The subjects consisted of two 50th percentile males (Volunteers 1 and 2), one 5th percentile female (Volunteer 3) and a Hybrid III 50th percentile male. All subjects were in near-side impacts. The pulses consisted of two 4 g pulses (6 and 8 kph) and a 4 g/8 kph followed by a m 2.5 g pulse to simulate a low curb impact. In the 6 and 8 kph pulses, the antropometric test devices' head trajectory is somewhat similar to the volunteers'. For near-sided/belted occupants, the peak lateral excursion was 327 - 53 mm for the volunteers, and 269 mm for the Hybrid III in the 6 kph pulse, while it was 321 - 35 mm respectively in the 8 kph pulse. It was also observed that, in the first phase of the motion, the Hybrid III vertical displacement remained positive while the volunteers' vertical displacement was initially negative. This is probably due to the rigidity of the Hybrid III spine and the lack of flexibility in its torso compared to humans. In the 4 g/8 kph followed by a m 2.5 g pulse, the lateral head excursion was higher with a Hybrid III than with volunteers. For near-sided/belted occupants, the lateral excursion was 155 - 10 mm for the volunteers and 291 mm for the Hybrid III. The results suggest that the Hybrid III is a useful tool to evaluate head kinematics in slow-speed lateral impacts at 6 and 8 kph. For the 4 g/8 kph pulse followed by a m 2.5 g pulse acceleration, a better correlation between the Hybrid III and volunteer head excursion may be needed to improve the biofidelity of the Hybrid III kinematics.