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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.

The object of this research program has been to extend the scope of earlier work to include long-duration head impacts and to develop new scaling relationships to allow extrapolation of impact data from infrahuman primates to living humans. A series of living primate side impacts to the head and torso was conducted in parallel with a series of impacts to human cadavers. Dimensional analysis techniques were employed to estimate in vivo human tolerance to side injury. The threshold of closed brain injury to humans was found to be 76 g for a pulse duration of 20 ms and an impact velocity of 43 ft/s (13.2 m/s). The maximum tolerable penetration to the chest was found to be 2.65 in (6.72 cm) for both the left and right sides. Scaling of abdominal injuries to humans was accomplished by employing a factor that relates impact contact area, animal mass, impact force, and pulse duration to injury severity.

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.

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.

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.

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.