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Throughout the first decade of the twenty first century, large improvements in occupant safety have been made in NASCAR®'s (National Association for Stock Car Auto Racing, Inc) race series. Enhancements to the occupant restraint system include the development and implementation of head and neck restraints, minimum performance requirements for belts and seats and the introduction of energy absorbing foam are a few highlights, among others. This paper discusses nineteen sled tests used to analyze hypothesized improvements to restraint system mounting geometry. The testing matrix included three sled acceleration profiles, three impact orientations, two Anthropomorphic Test Device (ATD) sizes as well as the restraint system design variables.

The purpose of this study is to provide an understanding of driver kinematics, injury mechanisms and spinal loads causing thoracolumbar spinal fractures in Indianapolis-type racing car drivers. Crash reports from 1996 to 2006, showed a total of forty spine fracture incidents with the thoracolumbar region being the most frequently injured (n=15). Seven of the thoracolumbar fracture cases occurred in the frontal direction and were a higher injury severity as compared to rear impact cases. The present study focuses on thoracolumbar spine fractures in Indianapolis-type racing car drivers during frontal impacts and was performed using driver medical records, crash reports, video, still photographic images, chassis accelerations from on-board data recorders and the analysis tool MADYMO to simulate crashes. A 50th percentile, male, Hybrid III dummy model was used to represent the driver.

This paper describes the results of an ongoing project in the GM Motorsports Safety Technology Research Program to investigate Indianapolis-type (Indy car) race car crashes using an on-board impact recorder as the primary data collection tool. The paper discusses the development of specifications for the impact-recording device, the selection of the specific recorder and its implementation on a routine basis in Indy car racing. The results from incidents that produced significant data (crashes with peak decelerations above 20 G) during the racing seasons from 1993 through the first half of 1998 are summarized. The focus on Indy car crashes has proven to provide an almost laboratory-like setting due to the similarity of the cars and to the relative simplicity of the crashes (predominantly planar crashes involving single car impacts against well-defined impact surfaces).

Two-dimensional film analysis was conducted to study the kinematics of the head and neck of 17 restrained human volunteers in 24 frontal impacts for acceleration levels from 6g to 15g. The trajectory of the head center of gravity relative to upper torso reference points and the rotation of head and neck relative to the lower torso during the forward motion phase were of particular interest. The purpose of the study was to analyze the head-neck kinematics in the mid-sagittal plane for a variety of human volunteer frontal sled tests from different laboratories using a common analysis method for all tests, and to define a common response corridor for the trajectory of the head center-of-gravity from those tests.

Recent action by some racecar sanctioning bodies making head/neck restraint use mandatory for competitors has resulted in a number of methods attempting to provide head/neck restraint. This paper evaluates the performance of a number of commercially available head/neck restraint systems using a stock car seating configuration and a realistic stock car crash pulse. The tests were conducted at an impact angle of 30 degrees to the right, with a midsize male Hybrid III anthropomorphic test device (ATD) modified for racecar crash testing. A six-point latch and link racing harness restrained the ATD. The goal of the tests was to examine the performance of the head/neck restraint without the influence of the seat or steering wheel. Three head/neck restraint systems were tested using a sled pulse with a 35 mph (56 km/h) velocity change and 50G peak deceleration. Three tests with three samples of each system were performed to assess repeatability.

This paper presents the rationale behind the development of a shoulder belt load cell suitable for application in racings cars. The design of the load cell and the operational parameters necessary for a research-quality measurement device for biomechanics research in racing car crashes and the performance of the device in sled tests are described.

The purpose of this paper is to establish injury assessment reference values specific to the CRABI 6-Month infant dummy for use in evaluating the interaction of rear-facing infant restraints with a deploying passenger airbag. The available literature on the biomechanics of child injury and mechanical response and the results of impact tests with various child and infant dummies are reviewed and summarized. Estimations of the injury assessment reference values for use with the CRABI 6-Month dummy are made using scaling techniques based on the principles of dimensional analysis and dummy test data from infant restraint tests under conditions where injuries are not likely to occur. The information developed in this report will allow the assessment of injury potential in tests of the interaction of passenger airbags with rear-facing infant restraints. This issue is of particular importance to vehicles with only front seats, such as pickup trucks and sport vehicles.

It is well known that the ability of the human body to withstand trauma is a function of its inherent strength, i.e., the strength of the bones and soft tissues. Yet, the properties of the bones and tissues change as a function of the individual's age. In this paper age effects on thoracic injury tolerances are studied by analyzing the mechanical properties of human bones and soft tissues and by examining experimental results found in the literature of thoracic impact tests to human cadavers. This work suggests that the adult age range can be divided into three age groups. Using piece-wise linear regression analyses, it has been determined that the reduction in injury tolerance from the “young” age group to the “elderly” group is approximately 20% under blunt frontal impact loading conditions and is as much as 70% under belt loading conditions.

This paper describes the initial phases of an on-going project in the GM Motorsports Safety Technology Research Program to investigate Indy car crashes using an on-board impact recorder as the primary data collection tool. The development of a database consisting of crash investigation data patterned after national highway crash databases is discussed. The data gathered and coded includes track and incident scene information, vehicle damage, and driver injuries, as well as the vehicle decelerations measured by the impact recorder. The paper discusses the development of specifications for the impact device, the selection of the specific recorder and its implementation on a routine basis in Indy car racing. The results from incidents that produced significant data during the 1993, 1994 and 1995 racing seasons are summarized.

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.

At the 2002 MSEC, we presented a paper on the sled test evaluation of racecar head/neck restraint performance (Melvin, et al. 2002). Some individuals objected to the 3 msec clip filtering procedures used to eliminate artifactual spikes in the neck tension data for the HANS® device. As a result, we are presenting the same test data with the spikes left in the neck force data to reassure those individuals that these spikes did not significantly affect the results and conclusions of our original paper. In addition we will add new insights into understanding head/neck restraint performance gained during two more years of testing such systems. This paper re-evaluates the performance of three commercially available head/neck restraint systems using a stock car seating configuration and a realistic stock car crash pulse. The tests were conducted at an impact angle of 30 degrees to the right, with a midsize male Hybrid III anthropomorphic test device (ATD) modified for racecar crash testing.

Recent developments in seat design for racecar drivers have proven to be very effective in minimizing injuries in side impacts. The features of the seats that present significant improvements over previous concepts are based on biomechanical principles that were learned from crash recorder based investigations of Indy car crashes. Insights gained from these studies led to an understanding of critical factors that provide effective support and protection of the driver in a high-severity side impact crash. Transferring these concepts from single seat chassis cars to stock car and sports car seats has led to significant improvements in driver side impact protection. The paper will describe these principles, present sled test performance data showing the benefits of proper seat design and will give examples of current commercially available seat designs for stock car and sports car racing.

This paper describes the development of an improved neck simulation that can be adapted to current anthropometric dummies. The primary goal of the neck design is to provide a reasonable simulation of human motion during impact while maintaining a simple, rugged structure. A synthesis of the current literature on cervical spine mechanics was incorporated with the results of x-ray studies of cervical spine mobility in human volunteers and with the analysis of head-neck motions in human volunteer sled tests to provide a background for the design and evaluation of neck models. Development tests on neck simulations were carried out using a small impact sled. Tests on the final prototype simulation were also performed with a dummy on a large impact sled. Both accelerometers and high-speed movies were used for performance evaluation.

This paper presents the results of direct impact tests and driving point impedance tests on the legs of seated unembalmed human cadavers. Variables studied in the program included impactor energy and impact direction (axial and oblique). Multiple strain gage rosettes were applied to the bone to determine the strain distribution in the bone. The test results indicate that the unembalmed skeletal system of the lower extremities is capable of carrying significantly greater loads than those determined in tests with embalmed subjects (the only similar data reported in the present literature). The strain analysis indicated that significant bending moments are generated in the femur with axial knee impact. The results of the impedance tests are used to characterize the load transmission behavior of the knee-femur-pelvis complex, and the impact test results are combined with this information to produce suggested response characteristics for dummy simulation of knee impact response.

The response of the head to impact in the posterior-to-anterior direction was investigated with live anesthetized and post-mortem primates.* The purpose of the project was to relate animal test results to previous head impact tests conducted with cadavers (reported at the 21st Stapp Car Crash Conference (1),** and to study the differences between the living and post-mortem state in terms of mechanical response. The three-dimensional motion of the head, during and after impact, was derived from experimental measurements and expressed as kinematic quantities in various reference frames. Comparison of kinematic quantities between subjects is normally done by referring the results to a standard anatomical reference frame, or to a predefined laboratory reference frame. This paper uses an additional method for describing the kinematics of head motion through the use of Frenet-Serret frame fields.

The general objective of the whole-Body Response (WBR) research program was to generate data on the kinematics and response of human surrogates in a realistic automobile impact environment. The program used a test configuration consisting of an idealized hard seat representation of a car seat with a three-point harness restraint system. Three different severity levels of crash test conditions were used. The human surrogates tested in this program were fifteen male cadavers*, a Hybrid II (Part 572) Anthropomorphic Test Device and a Hybrid III ATD recently developed by General Motors. In addition, mathematical simulations of the response and kinematics of a 50th percentile male occupant were performed at the three levels of crash severity, using the MVMA Two-Dimensional Crash Victim Simulator.

A series of 16 sled impact tests was conducted at the Highway Safety Research Institute sled facility to evaluate the effectiveness of restraint devices and systems currently being used to transport school-bus and wheelchair-seated handicapped children. A sled impact pulse of 20 m.p.h. and 16 G's was used for all tests. Eight tests involved wheelchairs in forward-facing and side-facing orientations for head-on and 33-degree oblique impacts. Another eight tests involved forward-facing bus seats for head-on and 33-degree oblique impacts. The results generally point out the ineffectiveness of many currently used devices and systems for protecting the child in a bus collision. In six of the eight bus seat tests the dummy's head struck the back of the bus seat in front. This was primarily because of a lack of upper-torso restraint.

Multiple axial knee impacts and/or a single lateral pelvis impact were performed on a total of 19 cadavers. The impacting surface was padded with various materials to produce different force-time and load distribution characteristics. Impact load and skeletal acceleration data are presented as functions of both time and frequency in the form of mechanical impedance. Injury descriptions based on gross autopsy are given. The kinematic response of the pelvis during and after impact is presented to indicate the similarities and differences in response of the pelvis for various load levels. While the impact response data cannot prescribe a specific tolerance level for the pelvis, they do indicate variables which must be considered and some potential problems in developing an accurate injury criterion.

A test series using unembalmed cadavers was conducted to investigate thoracic response differences in lateral impacts between high energy (rib fractures produced) and low energy (no rib fractures produced) testing and also the response to low energy impacts for different impact directions (frontal, 45°, and lateral). Five of the test subjects were instrumented with a nine-accelerometer package and an eighteen-accelerometer array to measure thoracic response. Seven of the test subjects were instrumented with a triaxial accelerometer on the head and a six-accelerometer array to measure thoracic response. Impact events were performed with either the UMTRI pendulum impact device or the UMTRI pneumatic impact device. The subject was struck with a free-traveling mass (25 or 56 kg) which was fitted with either a 15 cm round or 20 cm square rigid metal surface.

A two-dimensional finite element model of the head of a rhesus monkey was built to simulate the head acceleration experiments done by Gennarelli and his colleagues. The purposes of the study were to better understand the mechanisms of traumatic subdural hematoma and to estimate its threshold of occurrence. The brain was treated as an isotropic homogeneous elastic material with and without structural damping and the skull was treated as a rigid shell. To simulate Abel et al.'s (1) experiments, the head was subjected to an enforced forward rotation around the neck. The loading had an initial acceleration phase followed by deceleration. During both acceleration and deceleration phases, high shear stress (and thus strain) occurred at the vertex, where the parasagittal bridging veins are located. The deformation of the bridging vein depended on its orientation relative to the direction of impact.