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The present study describes the development of a refined finite element model of the human pelvis. The objectives of this research work were to: Statistically study the human pelvis geometry, and develop a parameterized model. Mechanically validate the model with regard to the available in-house experimental data. Model the injury mechanisms observed in the experimental studies. The significant dimensions of the pelvis were identified by statistical analysis of the pelvis geometry based on the Reynolds et al. data [1]. Those dimensions were used to classify the in-house tested pelves. An interpolation technique (Kriging [2, 3, 4, 5, 6, 7 and 8]) was then used in order to distort a reference mesh and adapt its geometry to the measured geometry of the tested pelvis. The mechanical validation of the model was carried out by comparing numerical and experimental results, and the influence of the geometrical variations on the behavior of the pelvis was thus assessed.

This study presents a detailed comparison of internally and externally measured chest deflections resulting from eight tests conducted on three male post mortem human subjects. A hydraulically driven shoulder belt loaded the anterior thorax under a fixed spine condition while displacement data were obtained via a high-speed 16-camera motion capture system (VICON MX™). Comparison of belt displacement and sternal displacement measured at the bone surface provided a method for quantifying effective change in superficial soft tissue depth at the mid sternum under belt loading. The relationship between the external displacement and the decrease in the effective superficial tissue depth was found to be monotonic and nonlinear. At 65 mm of mid-sternal posterior displacement measured externally, the effective thickness of the superficial tissues and air gap between the belt and the skin had decreased by 14 mm relative to the unloaded state.

A finite element human model has been developed to simulate occupant behavior and to estimate injuries in real-world car crashes. The model represents an average adult male of the US population in a driving posture. Physical geometry, mechanical characteristics and joint structures were replicated as precise as possible. The total number of nodes and materials is around 67,000 and 1,000 respectively. Each part of the model was not only validated against human test data in the literature but also for realistic loading conditions. Additional tests were newly conducted to reproduce realistic loading to human subjects. A data set obtained in human volunteer tests was used for validating the neck part. The head-neck kinematics and responses in low-speed rear impacts were compared between the measured and calculated results. The validity of the lower extremity part was examined by comparing the tibia force in a foot impact between the test data and simulation results.

This paper discusses struck-side occupant thoracic response to side-impact loading and the requirements of a sled system capable of reproducing the relevant motions of a laterally impacted vehicle. A simplified viscoelastic representation of a thorax is used to evaluate the effect of the door velocity-time profile on injury criteria and on the internal stress state of the thorax. Simulations using a prescribed door velocity-time profile (punch impact) are contrasted against simulations using a constant-velocity impact (Heidelberg-type impact). It is found that the stress distribution and magnitude within the thorax, in addition to the maximum thorax compression and viscous response, depend not only on the door-occupant closing velocity, but also on the shape of the door velocity-time profile throughout the time of contact with the occupant. A sled system capable of properly reproducing side-impact door and seat motion is described.

This paper compares restrained Hybrid III and THOR thoracic kinematics and cadaver injury outcome in 30° oblique frontal and in full frontal sled tests. Peak shoulder belt tension, the primary source of chest loading, changed by less than four percent and peak chest resultant acceleration changed by less than 10% over the 30° range tested. Thoracic kinematics were likewise insensitive to the direction of the collision vector, though they were markedly different between the two dummies. Mid-sternal Hybrid III chest deflection, measured by the standard sternal potentiometer and by supplemental internal string potentiometers, was slightly lower (∼10%) in the oblique tests, but the oblique tests produced a negligible increase in lateral movement of the sternum. In an attempt to understand the biofidelity of these dummy responses, a series of 30-km/h human cadaver tests having several collision vectors (0°, 15°, 30°, 45°) was analyzed.

Current crash dummy biofidelity standards include the estimated effects of tensing the muscles of the thorax. This study reviewed the decision to incorporate muscle tensing by examining relevant past studies and by using an existing mathematical model of thoracic impacts. The study finds evidence that muscle tensing effects are less pronounced than implied by the biofidelity standard response corridors, that the response corridors were improperly modified to include tensing effects, and that tensing of other body regions, such as extremity bracing, may have a much greater effect on the response and injury potential than tensing of only the thoracic musculature. Based on these findings, it is recommended that muscle tensing should be eliminated from thoracic biofidelity requirements until there is sufficient information regarding multi-region muscle tensing response and the capability to incorporate this new data into a crash dummy.

Rupture of the thoracic aorta is a leading cause of rapid fatality in automobile crashes, but the mechanism of this injury remains unknown. One commonly postulated mechanism is a differential motion of the aortic arch relative to the heart and its neighboring vessels caused by high-magnitude acceleration of the thorax. Recent Indy car crash data show, however, that humans can withstand accelerations exceeding 100 g with no injury to the thoracic vasculature. This paper presents a method to investigate the efficacy of acceleration as an aortic injury mechanism using high-acceleration, low chest deflection sled tests. The repeatability and predictability of the test method was evaluated using two Hybrid III tests and two tests with cadaver subjects. The cadaver tests resulted in sustained mid-spine accelerations of up to 80 g for 20 ms with peak mid-spine accelerations of up to 175 g, and maximum chest deflections lower than 11% of the total chest depth.

This paper presents thoracic response corridors developed using fifteen post-mortem human subjects (PMHS) subjected to single and double diagonal belt, distributed, and hub loading on the anterior thorax. We believe this is the first study to quantify the force-deflection response of the same thorax to different loading conditions using dynamic, non-impact, restraint-like loading. Subjects were positioned supine on a table and a hydraulic master-slave cylinder arrangement was used with a high-speed materials testing machine to provide controlled chest deflection at a rate similar to that experienced by restrained PMHS in a 48-km/h sled test. All loading conditions were tested at a nominally non-injurious level initially. When the battery of non-injurious tests was completed, a single loading condition was used for a final, injurious test (nominal 40% chest deflection).

This study evaluated the response of restrained post-mortem human subjects (PMHS) in 40 km/h frontal sled tests. Eight male PMHS were restrained on a rigid planar seat by a custom 3-point shoulder and lap belt. A video motion tracking system measured three-dimensional trajectories of multiple skeletal sites on the torso allowing quantification of ribcage deformation. Anterior and superior displacement of the lower ribcage may have contributed to sternal fractures occurring early in the event, at displacement levels below those typically considered injurious, suggesting that fracture risk is not fully described by traditional definitions of chest deformation. The methodology presented here produced novel kinematic data that will be useful in developing biofidelic human models.

The human body undergoes a variety of changes as it ages through adulthood. These include both morphological (structural) changes (e.g., increased thoracic kyphosis) and material changes (e.g., osteoporosis). The purpose of this study is to evaluate structural changes that occur in the aging bony thorax and to assess the importance of these changes relative to the well-established material changes. The study involved two primary components. First, full-thorax computed tomography (CT) scans of 161 patients, age 18 to 89 years, were analyzed to quantify the angle of the ribs in the sagittal plane. A significant association between the angle of the ribs and age was identified, with the ribs becoming more perpendicular to the spine as age increased (0.08 degrees/year, p=0.012). Next, a finite element model of the thorax was used to evaluate the importance of this rib angle change relative to other factors associated with aging.

This paper describes the injuries generated during dynamic belt loading to a porcine model of the 6-year-old human abdomen, and correlates injury outcomes with measurable parameters. The test fixture produced transverse, dynamic belt loading on the abdomen of 47 immediately post-mortem juvenile swine at two locations (upper/lower), with penetration magnitudes ranging from 23% – 65% of the undeformed abdominal depth, with and without muscle tensing, and over a belt penetration rate range of 2.9 m/s – 7.8 m/s. All thoracoabdominal injuries were documented in detail and then coded according to the Abbreviated Injury Scale (AIS). Observed injuries ranged from AIS 1 to AIS 4. The injury distribution matched well the pattern of injuries observed in a large sample of children exposed to seatbelt loading in the field, with most of the injuries in the lower abdomen.

Injury to the thorax is the predominant cause of fatalities in crash-involved automobile occupants over the age of 65, and many elderly-occupant automobile fatalities occur in crashes below compliance or consumer information test speeds. As the average age of the automotive population increases, thoracic injury prevention in lower severity crashes will play an increasingly important role in automobile safety. This study presents the results of a series of sled tests to investigate the thoracic deformation, kinematic, and injury responses of belted post-mortem human surrogates (PMHS, average age 44 years) and frontal anthropomorphic test devices (ATDs) in low-speed frontal crashes. Nine 29 km/h (three PMHS, three Hybrid III 50th% male ATD, three THOR-NT ATD) and three 38 km/h (one PMHS, two Hybrid III) frontal sled tests were performed to simulate an occupant seated in the right front passenger seat of a mid-sized sedan restrained with a standard (not force-limited) 3-point seatbelt.

The abdomen is the second most commonly injured region in children using adult seat belts, but engineers are limited in their efforts to design systems that mitigate these injuries since no current pediatric dummy has the capability to quantify injury risk from loading to the abdomen. This paper develops a porcine (sus scrofa domestica) model of the 6-year-old human's abdomen, and then defines the biomechanical response of this abdominal model. First, a detailed abdominal necropsy study was undertaken, which involved collecting a series of anthropometric measurements and organ masses on 25 swine, ranging in age from 14 to 429 days (4-101 kg mass). These were then compared to the corresponding human quantities to identify the best porcine representation of a 6-year-old human's abdomen. This was determined to be a pig of age 77 days, and whole-body mass of 21.4 kg.

This study focuses on the phenomenon of lap belt slip on the iliac spines of the pelvis, commonly named “submarining ”. The first objective was to compare the interaction between the pelvis and the lap belt for both dummies and Post Mortem Human Subjects (PMHS). The second objective was to identify parameters influencing the lap belt hooking by the pelvis. For that purpose, a hydraulic test device was developed in order to impose the tension and kinematics of the lap belt such that they mimic what occurs in frontal car crashes. The pelvis was firmly fixed on the frame of this sub-system test-rig, while the belt anchorages were mobile. Fourteen tests on four Post-Mortem Human Subjects (PMHS) and fifteen tests on the THOR NT, Hybrid III 50th and Hybrid III 95th percentile dummies were carried out. The belt tension was kept constant while a dynamic rotation was imposed on the belt anchorages.

Traumatic aortic rupture (TAR) accounts for a significant mortality in automobile crashes. A numerical method by means of a mesh-based code coupling is employed to elucidate the injury mechanism of TAR. The aorta is modeled as a single-layered thick wall composed of two families of collagen fibers using an anisotropic strain energy function with consideration of viscoelasticity. A set of constitutive parameters is identified from experimental data of the human aorta, providing strict local convexity. An in vitro aorta model reconstructed from the Visible Human dataset is applied to the pulsatile blood flow to establish the references of mechanical quantities for physiological conditions. A series of simulations is performed using the parameterized impact pulses obtained from frontal sled tests.

No experimental data exist quantifying the force-deformation behavior of the pediatric chest when subjected to non-impact, dynamic loading from a diagonal belt or a distributed loading surface. Kent et al., (2006) previously published juvenile abdominal response data collected using a porcine model. This paper reports on a series of experiments on a 7-year-old pediatric post-mortem human subject (PMHS) undertaken to guide the scaling of existing adult thoracic response data for application to the child and to assess the validity of the porcine abdominal model. The pediatric PMHS exhibited abdominal response similar to the swine, including the degree of rate sensitivity. The upper abdomen of the PMHS was slightly stiffer than the porcine behavior, while the lower abdomen of the PMHS fit within the porcine corridor. Scaling of adult thoracic response data using any of four published techniques did not successfully predict the pediatric behavior.

Very little experimental research has focused on the kinematics, dynamics, and injuries of rear-seated occupants. This study seeks to develop a baseline response for rear-seated post mortem human surrogates (PMHS) in frontal crashes. Three PMHS sled tests were performed in a sled buck designed to represent the interior rear-seat compartment of a contemporary midsized sedan. All occupants were positioned in the right-rear passenger seat and subjected to simulated frontal crashes with an impact speed of 48 km/h. The subjects were restrained by a standard, rear seat, 3-point seat belt. The response of each subject was evaluated in terms of whole-body kinematics, dynamics, and injury. All the PMHS experienced excessive forward translation of the pelvis resulting in a backward rotation of the torso at the time of maximum forward excursion.

This study investigates the performance of a 3-point restraint system incorporating an inflatable shoulder belt with a nominal 2.5-kN load limiter and a non-inflatable lap belt with a pretensioner (the “Airbelt”). Frontal impacts with PMHS in a rear seat environment are presented and the Airbelt system is contrasted with an earlier 3-point system with inflatable lap and shoulder belts but no load-limiter or pretensioners, which was evaluated with human volunteers in the 1970s but not fully reported in the open literature (the “Inflataband”). Key differences between the systems include downward pelvic motion and torso recline with the Inflataband, while the pelvis moved almost horizontally and the torso pitched forward with the Airbelt. One result of these kinematic differences was an overall more biomechanically favorable restraint loading but greater maximum forward head excursion with the Airbelt.

The literature contains a wide range of response data describing the biomechanics of isolated body regions. Current data for the validation of frontal anthropomorphic test devices and human body computational models lack, however, a detailed description of the whole-body response to loading with contemporary restraints in automobile crashes.

Rear seat adult occupant protection is receiving increased attention from the automotive safety community. Recent anthropomorphic test device (ATD) studies have suggested that it may be possible to improve kinematics and reduce injuries to rear seat occupants in frontal collisions by incorporating shoulder-belt force-limiting and pretensioning (FL+PT) technologies into rear seat 3-point belt restraints. This study seeks to further investigate the feasibility and potential kinematic benefits of a FL+PT rear seat, 3-point belt restraint system in a series of 48 kmh frontal impact sled tests (20 g, 80 ms sled acceleration pulse) performed with post mortem human surrogates (PMHS). Three PMHS were tested with a 3-point belt restraint with a progressive (two-stage) force limiting and pretensioning retractor in a sled buck representing the rear seat occupant environment of a 2004 mid-sized sedan.