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A study has been conducted as an initial step in determining the differences observed between the motions of a living human impact sled test subject and a dummy test subject. The mechanism which is proposed for accomplishing this is the HSRI Two-Dimensional Mathematical Crash Victim Simulator. A series of measurements were taken on human test subjects, including classical and nonclassical anthropometric measurements, range of motion measurements for the joints, and maximum foot force measurements. A series of mathematical expressions has been used to predict body segment weight, centers of gravity, and moments of inertia using the results of the various body measurements. It was then possible to prepare a data set for use with the mathematical model.

Advanced crash-impact protective equipment and techniques which have application to crew and passenger crash safety in jet transport aircraft have been evaluated. Thirty-two state-of-the-art concepts have been analyzed from a systems engineering viewpoint with respect to several engineering, psychological, and medical disciplines. In order to provide a framework to determine the function level of each concept, an event-oriented flow chart of the crash and escape event has been prepared. The 17 events occurring during a crash are included, beginning with system installation and concluding with emergency evacuation of a disabled aircraft. Performance with respect to the events on the flow chart are rated in terms of hazards of system use, maintainability, reliability, human factors, and other technological considerations.

The effectiveness of restraint systems in preventing fatalities or reducing injury has been estimated by extrapolation of data from several sources: (1) Sled tests with dummies (2) Analysis of accident case studies (3) Statistical comparison of belted and unbelted persons in crashed cars. (4) Before and after studies (e.g., with respect to belt-usage legislation, or as with the 1974 starter-interlock program) Fatality reduction estimated by the case study method is on the order of 30 percent, but by the statistical comparison method at 50 percent or sometimes as high as 60 percent. Other differences (e.g., driving habits) between belted and unbelted persons explain the disagreement between the two estimates. More complete analysis of available accident data suggests that the higher values were obtained without correction for such factors as crash severity or occupant age.

The literature on headlamp aiming is surveyed in detail to pinpoint the various sources and magnitudes of aim variance. Four major sources of variance are identified (differences between beam and mounting plane, photometric changes in use, long axis alignment, and human factors), along with a number of others of lesser consequence. Illustrations are offered showing the expected population variance under a variety of conditions. It is apparent that, at the present state-of-the-art, a substantial percentage of the lamp population can be expected to be beyond the limits recommended in SAE J599c. It is further apparent that this would be true regardless of whether or not a vehicle inspection program is in operation. Recommendations are given regarding research emphasis in headlighting. Ways of reducing variance from the most significant sources are considered and recommendations offered.

Basic physical characteristics of the neck have been defined which have application to the design of biomechanical models, anthropometric dummies, and occupant crash protection devices. The study was performed using a group of 180 volunteers chosen on the basis of sex, age (18-74 years), and stature. Measurements from each subject included anthropometry, cervical range-of-motion (observed with both x-rays and photographs), the dynamic response of the cervical flexor and extensor muscles to a controlled jerk, and the maximum voluntary strength of the cervical muscles. Data are presented in tabular and graphic form for total range-of-motion, cervical muscle reflex time, decelerations of the head, muscle activation time, and cervical muscle strength. The range-of-motion of females was found to average 1-12 deg greater than that of males, depending upon age, and a definite degradation in range-of-motion was observed with increasing age.

Present head restraint systems quite often restrict rearward visibility, and when not properly adjusted, their effectiveness suffers. The deployable head restraint can overcome both these problems and in addition provide head restraint performance better than fixed systems. This paper describes a project to study the feasibility of deployable head restraints. Starting with two-dimensional computer simulations of front seat occupant kinematics in rear-end collisions, initial performance criteria for deployment times, and restraint configurations were determined for various impact velocities. Based on these criteria, two types of deployable systems were designed and constructed, one an inflatable system and the other a rigid sliding system. These prototype systems then underwent a test and development program using anthropomorphic dummies and an impact sled. The test program evaluated the effectiveness of the head restraint systems under high- and low-speed crash simulations.

This paper reports the results of a study which had as its aim the determination of braking performance currently achievable by buses, trucks, and tractor-trailers, and the improvement of this performance by use of advanced braking systems. Both vehicle testing and analytical techniques, including dynamic modeling and simulation, were used in the program. Performance qualities essential to braking systems are enumerated, which, when given quantitative definition in the light of performance achievable, can form the basis of rational performance requirements for commercial vehicles.

A variety of mechanical head forms is used today in the evaluation of the crashworthiness of automotive interiors and the effectiveness of helmet designs. Most head forms are of a very rigid metallic construction, although frangible head forms that indicate skull fracture are presently available. None of the existing head forms can be considered a complete mechanical analog to the human head in terms of mechanical response. This paper describes the initial phases of the development of such a head form. The first step in the development of the model was the determination of the pertinent mechanical properties of the tissues of the human head (scalp, skull bone, dura mater, and brain). A testing program which determined these properties at both static and dynamic strain rates is described and the results are summarized. The second phase of the program was to find and develop synthetic materials which duplicated the mechanical properties of the human tissues.

A study of the biomechanical factors concerned with the design of side structures and doors for crashworthiness has been made. Questions regarding optimum stiffness, location of reinforcing members, effect of armrests, and padding have been answered within the framework of injury criteria models. Results of animal studies, cadaver studies, and anthropometric dummies have been combined to produce injury criteria for lateral impacts to the head, thorax, and abdomen. Impacts were applied utilizing a specially designed “air gun” in a laboratory environment emphasizing reproducibility and control. Full-scale crash simulations were performed on an impact sled to verify the results of the more specialized tests and analyses. Scaled models of current production doors were used in the animal series. Scaling relationships for various species of animals have been developed and extrapolated to man. Significant differences in right and left side tolerances to impact were noted and detailed.

A sample population of 51 male and 57 female subjects ranging in age from 18 to 78 years was assembled and tested in six different vehicles for preferred seat positions under non-driving and driving conditions. Volunteer subjects were selected by age, stature, and weight criteria in order to match the U.S. adult population to the extent practical. Preliminary analyses of these data suggest that on a total sample basis there is little difference between seat positions selected under non-driving and driving conditions, but that individuals may show significant differences. The small differences in group mean positions observed in this study may be due to a seat belt and/or an initial seat position factor. Post-drive seat position results were analyzed in a variety of ways to identify factors that may influence a person's preferred seat position.

Driver-vehicle tests were performed in which the deceleration/pedal-force ratio (i.e., gain), pedal-displacement level, speed, surface-tire friction, and driver characteristics were systematically varied in order to determine the influence of these variables upon minimum stopping distance and other performance variables. Tests performed on a low coefficent of friction surface showed that high values of deceleration/pedal-force gain result in a greater number of wheel lockups and longer stopping distances compared to results achieved with intermediate or low deceleration/pedal-force gains. Tests performed on the two test surfaces with high and intermediate levels of friction showed that low deceleration/pedal-force gains produced longer stopping distances than were obtained with high gain, even though a high-gain brake system causes higher frequencies of wheel lockup.

In a previous study, an extensive study of the dynamic performance of child seating systems indicated that little protection was provided under circumstances other than panic braking. This study was performed with impact test conditions of 30 mph frontal and 20 mph lateral and rear barrier impacts with seating systems meeting the requirements of FMVSS 213. Additionally, the performance of prototype seats developed under contract with the Department of Transportation under similar test conditions will be presented to compare the protective qualities available with seats of current design and those that could become available in the future. The performance of the child seats will be evaluated using two criteria, motion limits and acceleration limits. It is believed that the performance of child seats can be determined without the extensive test equipment and facilities required for adult seating and restraint systems.

Serious injuries are caused to the chest and thoracic organs both in front and side automobile collisions, and statistical surveys indicate that overall chest injuries are the third most frequent after head and the lower limbs. For safer design of restraint systems and vehicle interiors experimental data has to be obtained to establish chest injury criteria. Unembalmed human cadavers were used to conduct nine frontal and fourteen lateral impacts including four with a simulated arm rest. All impacts used a six inch (15.2 cm) diameter impactor with impact velocities ranging from 12 mph (19.3 kph) to 20 mph (32.2 kph). Chest impacts were also conducted on rhesus monkeys and baboons to establish primate-human injury scaling criteria. Four human volunteers were used to obtain static load deflection curves in the lateral and frontal directions. The results of the above experiments and those conducted by other investigators are presented and analyzed.

Blunt abdominal trauma is a major cause of death in the United States. However, little experimental work has been done to clarify the mechanism of blunt abdominal injury and to quantify tolerance parameters for the abdominal organs. This paper describes a joint study by the Highway Safety Research Institute and the Section of General Surgery of The University of Michigan in which direct impacts were applied to livers and kidneys. The tests were performed in a high-speed testing machine at a controlled ram velocity and stroke limit. The organ was surgically mobilized in anesthesized Rhesus monkeys and then placed on a load cell while still being perfused in the living animal. Tests were performed at ram speeds of 120, 6000, and 12000 in/min (5, 250,and 500 cm/s). The resulting load-deflection data were normalized and average stress-strain curves plotted for each test. In addition, the resulting injury severity was estimated immediately after impact using an injury scale of 1 to 5.

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.

The current federal accident data collection system is inadequate. It does not produce representative data essential for answering cause-and-effect questions concerning accidents, injuries, and fatalities, and it does not produce adequate data essential for conducting cost-benefit analyses of changes in vehicle designs, highway designs, or driver licensing policies. A proposed federal data collection system (SIR) can solve those problems at a total cost of about $6 million a year. The SIR system would include 30 investigating teams precisely located throughout the U.S., and would include a Sampling program, an In-depth program, and a Rapid-response program. The sooner this system is established, the sooner government and industry will begin to obtain accurate and reliable answers to pressing questions in the field of highway safety.

Mechanical properties have been obtained from a recent series of truck tire tests using the Highway Safety Research Institute's (HSRI) flat bed tire testing machine. In addition to the vertical and lateral spring rates, a set of three parameters characterizing traction properties of the rolling tire are defined and measured. The influence of tire load and inflation pressure on mechanical properties is found to be significant. Carpet plots of lateral force versus tire operating variables such as camber and slip angle are used to illustrate the effect of changes in ply rating, tread pattern, and wear. Corresponding variations in the mechanical properties are noted. The results of an experiment to determine the relationship between single tire and dual tire force and moment producing capabilities are also described.

This paper describes an injury criteria model implemented in computer language, and a restraint system effectiveness index for evaluating the degree to which the vehicle environment can prevent or reduce occupant injuries. The need for criteria of this type is based on the fact that if the degree of protection offered to a vehicle occupant by a restraint system or a vehicle interior (a function of the distribution and magnitude of the forces transmitted to the occupant) could be expressed in quantitative terms, then, more meaningful comparisons could be made between restraint configurations, and, areas of needed biomechanical research and statistical accident investigations could be more readily identified on the basis of the sensitivity of the results when the injury or effectiveness criteria are applied. The injury criteria model consists of three parts: 1.

A series of mathematical models of the interaction between an occupant and the interior of a vehicle is presented. The following parameter studies using an eight-mass, two-dimensional model are discussed: belt material properties, belt slack, belt geometric configuration, and comparison of seats with and without headrests in rear impact. In addition, it is demonstrated by example that simple mathematical models can perform a valuable service in laying the groundwork for more sophisticated analytical and experimental work as well as yielding short term results. Finally, three-dimensional models are discussed. It is shown that a three-mass, three-dimensional model is a logical extension of current simulation efforts in order to provide insight into occupant response in oblique and lateral impact as well as nonsymmetric restraint systems.

This paper discusses the problem of occupant protection in severe rear-end collisions from the standpoint of high performance seat structures and head restraints. Consideration is given to both fixed head restraints and to deployable head restraints. Two-dimensional computer simulations of occupant kinematics in a variety of rear-end collisions are utilized to provide initial performance criteria for head restraint design configurations. The resulting prototype system underwent a test and development program on an impact sled. The results of the various prototype performances and general criteria for high performance head restraint systems are discussed.