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A PC based interactive program was developed to simulate the unfolding and deploying process of a driver side airbag in the sagittal plane. The airbag was represented by a series of nodes. The maximum allowable stretch was less or equal to one between any two nodes. We assumed that the airbag unfolding was pivoted about folded points. After the completion of the unfolding process the airbag would begin to deploy. During the deploying process, two parameters were used to determine the nodal priority of the inflation. The first parameter was the distance between the instantaneous and final positions of a node. Nodes with longer distances to travel will have to move faster. We also considered the distance between the current nodal position and the gas inlet location. For a node closer to the gas inlet, we assumed that the deploying speed was faster. A graphical procedure was used to calculate the area of the airbag.

This is a summary of a paper which first appeared in the International Journal of Crashworthiness under the title: “Side Impact Protection - Occupants in the Far-Side Seat”, Vol. 3, No.2, pp 93-122. Readers are directed to the full paper for a more comprehensive discussion of the issues presented here. Much of the applied vehicle side impact occupant protection research to date has concentrated on occupants seated beside the struck side of vehicles. These occupants are defined as ‘near-side’ occupants. Real world crash evidence however has shown that occupants seated on the side away from the struck side, defined as ‘far-side’ occupants, are still subject to a risk of injury. This paper examines side impact epidemiology from an injury causation perspective, and endeavours to explain evidence indicating head injuries and seat belt related injuries constitute a significant proportion of all far-side impact injuries.

This study identified the mechanical properties of ten cadaveric lumbar spines and two Hybrid III lumbar spines. Eight tests were performed on each specimen: tension, compression, anterior shear, posterior shear, left lateral shear, flexion, extension and left lateral bending. Each test was run at a displacement rate of 100 mm/sec. The maximum displacements were selected to approximate the loading range of a 50 km/h Hybrid III dummy sled test and to be non-destructive to the specimens. Load, linear displacement and angular displacement data were collected. Bending moment was calculated from force data. Each mode of loading demonstrated consistent characteristics. The load-displacement curves of the Hybrid III lumbar spine demonstrated an initial region of high stiffness followed by a region of constant stiffness.

A three-dimensional finite element model of a human neck has been developed in an effort to study the mechanics of cervical spine while subjected to impacts. The neck geometry was obtained from MRI scans of a 50th percentile male volunteer. This model, consisting of the vertebrae from C1 through T1 including the intervertebral discs and posterior elements, was constructed primarily of 8-node brick elements. The vertebrae were modeled using linear elastic-plastic materials, while the intervertebral discs were modeled using linear viscoelastic materials. Sliding interfaces were defined to simulate the motion of synovial facet joints. Anterior and posterior longitudinal ligaments, facet joint capsular ligaments, alar ligaments, transverse ligaments, and anterior and posterior atlanto-occipital membranes were modeled as nonlinear bar elements or as tension-only membrane elements. A previously developed head and brain model was also incorporated.

The need for a consumer information on car safety is growing steadily. Up to now, the consumer information about crash-tested new cars has been provided, but this should be supplemented by safety ratings based on real-world accidents which reflect all types of accident circumstances. The possibilities and limits of the necessary ""Quality Criteria for the Safety Assessment of Cars based on Real- World Crashes'' are analyzed in an EU project in cooperation of research institutes, industry and universities. The paper summarizes the results of three major objectives within this ""SARAC'' project. - The existing rating procedures worldwide have been analyzed and are described by their methods and the assessment criteria/crash parameters used.

A preliminary case-control study of passenger airbag deployments in frontal crashes (in which a passenger was present) was undertaken. The study was conducted as part of an on-going study of vehicle crash performance and occupant injury at Monash University Accident Research Center (MUARC). The results of this preliminary study suggest that the US experience of fatalities caused by interaction of the passenger with the deploying airbag is not shared in Australia. This is probably because the seat-belt use in this study was 100%. These preliminary results reinforce the view that such airbags should be used as supplementary restraint systems. Further studies are planned to monitor the performance of passenger-airbags and to provide more in-depth analyses when more data become available.

This study presents some results from a case-control study of crashed vehicles equipped with Australian airbag technology (Supplementary Restraint Systems). Vehicles were inspected and occupants interviewed according to the National Accident Sampling System (NASS). Data were available for 383 belted drivers involved in frontal crashes including 253 drivers in airbag-equipped vehicles and 130 drivers in non-airbag vehicles. The analysis revealed reductions in the numbers of injuries to the head, face, chest and neck in the airbag-equipped vehicles although the numbers of upper extremity injuries increased. At higher injury severities (AIS2+) reductions were also observed in injuries to the head, face, neck and chest. Further analysis using Harm as an outcome measure found that the mean Harm per driver (in terms of $AUD) were 60% greater in the non-airbag vehicles compared with the airbag-equipped vehicles.

Lower extremity injuries in frontal automotive crashes usually occur with footwell intrusion where both the knee and foot are constrained. In order to identify factors associated with tibial shaft injury, a series of numerical simulations were conducted using a finite element model of the whole human body. These simulations demonstrated that tibial mid-shaft injuries in frontal crashes could be caused by an abrupt change in velocity and a high rate of footwell intrusion.

The objective of the ISIP Project has been to develop a methodology to allow vehicle designers to optimize safety systems of vehicles in side impacts. This optimization was based on the minimization of the cost of injury or Harm. To form the link between the safety system protective capability in a crash and the cost of injury to the occupant required the development of a series of lateral impact Injury Assessment Functions (IAFs). These IAFs had to be able to predict the risk of injury, in AIS, for each of the major body regions of the occupant. The injury predictions were used to derive Harm for the crash and were based on the responses of a human surrogate, the BioSID. This paper describes the development of these lateral injury IAFs from the analysis of cadaver test data.

This paper includes an overview of a collaborative research project of Improved Side Impact Protection (ISIP) that commenced in 1997. The research program was sponsored by the Australian Research Council and involved a partnership of industry, government and research agencies, both in Australia and overseas. The overall aim was to develop a new approach to optimizing vehicle design using Harm as the main outcome criteria. The program involved a number of research activities including mass data analysis, in-depth real-world crash investigations, simulation modelling and the development of a family of Injury Assessment Functions. The paper outlines the structure and progress of these activities, summarizes the results and provides an overview of the optimizer model emanating from this research.

Vehicle crash compatibility is of major interest in road safety research as it focuses on both vehicle crashworthiness and aggressivity. Most of the research into vehicle safety to date has focused on vehicle crashworthiness promoting vehicle designs that overlook the protection of occupants in the ‘other’ vehicle in a vehicle-to-vehicle collision. Most recently this issue has lead to the development of new methods of vehicle aggressivity rating. This study presents two proposed vehicle aggressivity rating methods. The ‘subject’ car aggressivity is estimated based on injury outcome to the driver of the ‘other’ vehicle involved in a two-vehicle collision. The logistic regression technique is applied in order to adjust risk of driver injury for a number of endogenous and exogenous factors. The ability of the methods to ‘rate’ vehicle models in terms of their aggressivity performance in two-vehicle crashes is briefly described.

A nonlinear foam was added to a previously created three-dimensional finite element model of the Hybrid III dummy chest which consisted of six steel ribs, rib damping material, the sternum, a spine box and a pendulum. Two standard calibration pendulum impact tests for a Hybrid III dummy chest were used to validate the new model. An explicit finite element analysis code PAM-CRASH was utilized to simulate the dynamic process. At impact velocities of 6.7 m/s and 4.3 m/s, the force and deflection time history as well as the force-deflection plots showed good agreement between model predictions and calibration data. Peak strains also agreed well with experimental data.

Auto racing has been in vogue from the time automobiles were first built. With the dawn of modern cars came higher engine capacities; the speeds involved in these races and crashes increased as well. However, the advent of passive restraint systems such as the helmet, HANS (Head and Neck Support device), multi-point harness system, roll cage, side and frontal crush zones, racing seats, fire retardant suits, and soft-wall technology, have greatly improved the survivability of the drivers in high-speed racing crashes. Three left lateral crashes from Begeman and Melvin (2002), Case #LAS12, #IND14 and #99TX were used as inputs to the Wayne State Human Body Model (WSHBM) in a simulated racing buck. Twelve simulations with delta-v, six-point harness and shoulder pad as design variables were analyzed for the average maximum principal strain (AMPS) in the aorta. The average AMPS for the high-speed crashes were 0.1551±0.0172 while the average maximum pressure was 110.50±4.25 kPa.

A three-dimensional finite element model of the Hybrid III dummy head-neck complex was created to simulate the Amended Part 572 Head-Neck Pendulum Compliance Test, of the Code of Federal Regulations. The model consisted of a rigid head and five circular aluminum disks joined together by butyl elastomer rubber. Contact surfaces were defined to allow the anterior neck to separate upon an application of extension moments. Two mounting positions, one for flexion and the other one for extension, were used to simulate the head-neck calibration tests. An explicit finite element code PAM-CRASH was utilized to simulate the model dynamic responses. Simulation results were compared to experimental data obtained from First Technology Safety Systems Inc. Model predictions agreed well in both flexion and extension. This model can be used to study the head-neck biomechanics of the existing dummy as well as in the development of new dummies.

After a rear end impact, various clinical symptoms are often seen in car occupants (e.g. neck stiffness, strain, headache). Although many different injury mechanisms of the cervical spine have been identified thus far, the extent to which a single mechanism of injury is responsible remains uncertain. Apart from hyperextension or excessive shearing, a compression of the cervical spine can also be seen in the first phase of the impact due to ramping or other mechanical interactions between the seat back and the spine. It is hypothesized that this axial compression, together with the shear force, are responsible for the higher observed frequency of neck injuries in rear end impacts versus frontal impacts of comparable severity. The axial compression first causes loosening of cervical ligaments making it easier for shear type soft tissue injuries to occur.

The mechanisms of knee fracture were studied experimentally using cadaveric knees and analytically by computer simulation. Ten 90 degree flexed knees were impacted frontally by a 20 kg pendulum with a rigid surface, a 450 psi (3.103 MPa) crush strength and a 100 psi (0.689 MPa) crush strength aluminum honeycomb padding and a 50 psi (0.345 MPa) crush strength paper honeycomb padding at a velocity of about five m/s. During rigid surface impact, a patella fracture and a split condylar fracture were observed. The split condylar fracture was generated by the patella pushing the condyles apart, based on a finite element model using the maximum principal stress as the injury criterion. In the case of the 450 psi aluminum honeycomb padding, the split condylar fracture still occurred, but no patella fractures were observed because the honeycomb provided a more uniform distribution of patella load. No bony fractures in the knee area occurred for impacts with a 50 psi paper honeycomb padding.

Previously, a 10-year-old (YO) pediatric thorax finite element model (FEM) was developed and verified against child chest stiffness data measured from clinical cardiopulmonary resuscitation (CPR). However, the CPR experiments were performed at relatively low speeds, with a maximum loading rate of 250 mm/s. Studies showed that the biomechanical responses of human thorax exhibited rate sensitive characteristics. As such, the studies of dynamic responses of the pediatric thorax FEM are needed. Experimental pediatric cadaver data in frontal pendulum impacts and diagonal belt dynamic loading tests were used for dynamic validation. Thoracic force-deflection curves between test and simulation were compared. Strains predicted by the FEM and the injuries observed in the cadaver tests were also compared for injury assessment and analysis. This study helped to further improve the 10 YO pediatric thorax FEM.

One of the leading causes of death in automotive crashes is traumatic rupture of the aorta (TRA) or blunt aortic injury (BAI). The risk of fatality is high if an aortic injury is not detected and treated promptly. The objective of this study is to investigate TRA mechanisms using finite element (FE) simulations of reconstructed real-world accidents involving aortic injury. For this application, a case was obtained from the William Lehman Injury Research Center (WLIRC), which is a Crash Injury Research and Engineering Network (CIREN) center. In this selected crash, the case vehicle was struck on the left side with a Principal Direction of Force (PDoF) of 290 degrees. The side structure of the case vehicle crushed a maximum of 0.33 m. The total delta-V was estimated to be 6.2 m/s. The occupant, a 62-year old mid-sized male, was fatally injured. The occupant sustained multiple rib fractures, laceration of the right ventricle, and TRA, among other injuries.

The objective of this work was to evaluate a new tool for assessing brain injury. Many race car drivers have suffered concussion and other brain injuries and are in need of ways of evaluating better head protective systems and equipment. Current assessment guidelines such as HIC may not be adequate for assessing all scenarios. Finite element models of the brain have the potential to provide much better injury prediction for any scenario. At a previous Motorsports conference, results of a MADYMO model of a racing car and driver driven by 3-D accelerations recorded in actual crashes were presented. Model results from nine cases, some with concussion and some not, yielded head accelerations that were used to drive the Wayne State University Head Injury Model (WSUHIM). This model consists of over 310,000 elements and is capable of simulating direct and indirect impacts. It has been extensively validated using published cadaveric test data.

A total of eight low-speed, rear-end impact tests using two Post Mortem Human Subjects (PMHS) in a seated posture are reported. These tests were conducted using a HYGE-style mini-sled. Two test conditions were employed: 8 kph without a headrestraint or 16 kph with a headrestraint. Upper-body kinematics were captured for each test using a combination of transducers and high-speed video. A 3-2-2-2-accelerometer package was used to measure the generalized 3D kinematics of both the head and pelvis. An angular rate sensor and two single-axis linear accelerometers were used to measure angular speed, angular acceleration, and linear acceleration of T1 in the sagittal plane. Two high-speed video cameras were used to track targets rigidly attached to the head, T1, and pelvis. The cervical spine kinematics were captured with a high-speed, biplane x-ray system by tracking radiopaque markers implanted into each cervical vertebra.