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Vehicle change in velocity is recognized as one of the most influential parameters on occupant kinematics and injury potential in motor vehicle collisions. Basic engineering principals and some recent epidemiological research indicate the characteristics of the vehicle velocity change, such as the shape and duration of the acceleration vs. time pulse, may also be important. Automotive bumper designs could be enhanced by recognizing these characteristics to potentially influence occupant kinematics and Whiplash Associated Disorders (WAD) in low speed rear impacts. Low speed rear impacts were conducted with a Delta V of 11 km/h using the BioRID P3 anthropomorphic test device. Nominal pulse durations of 80, 100, 140 and 180 msec were tested by varying the dimensions of a foam interface between the impacting pendulum and the rear surface of the test vehicle.

In past years, considerable research has been devoted to occupant response in a variety of low-velocity, bumper-to-bumper impacts. In many crashes, however, the involvement of a braking vehicle or a higher ground clearance vehicle results in an override/underride type crash. The amount of vehicle damage can be significantly greater during such an impact because of the involvement of non-structural components above and below the bumper systems of the involved vehicles. Ten tests were conducted using five target vehicles, each occupied by an instrumented female driver. Each vehicle was tested in a bumper-to-bumper impact and then an override/underride configuration in increasing severity. An independent body shop estimator was employed to document the damage and prepare repair estimates for each test. In each test the vehicle and occupant accelerations were monitored.

A search of the automotive collision trauma literature reveals that over the last 35 years shows that there have been less than ten published Society of Automotive Engineers (SAE) articles describing the collision effects and resulting human occupant kinematics in low speed side impact collisions. The aim of this study was to quantify the occupant response for both male and female occupants for a battery of low-speed side impacts with various impact speeds and configurations. Eight volunteers were used in a series of twenty-five staged side impact collisions with impact speeds ranging from approximately 2 km/h to 10 km/h and impact configurations to the front, middle and rear side portions of the vehicle. A NHTSA FMVSS 301 moving barrier was used as the impacting vehicle. A stiff bumper was constructed to fit the front of the barrier and was attached at a normal passenger vehicle bumper height. Occupant and vehicle responses were monitored by accelerometers and high-speed video.

Interest in the mitigation of whiplash associated disorders (WAD) has increased in priority over the last 10 years, and an increasing number of human subject rear-end collision tests have been conducted to assist in the understanding of WAD. Traditionally this testing has examined the effects of variations in occupant characteristics (age, height, gender, etc.), seat characteristics (geometrical and constitutive), and impact severity. This data has resulted in advancements in the understanding of WAD and has provided occupant performance corridors at specific velocity changes, however no controlled study has examined the singular effect of incremental velocity change increases on occupant kinematics. Moreover, while vehicle velocity change is typically employed as a singular measure of impact severity, it is of interest to examine whether this or other impact-related parameters, such as energy or acceleration, are also correlated with occupant kinematics.

Research into the biomechanics of low speed rear impacts has focused primarily on the kinematic responses of anthropometric dummies and human subjects. Occupant muscular activity during low speed rear impacts remains largely unquantified however. The current study enhances the existing database of human subject test exposures with an emphasis on electromyographic activity before, during, and after low speed rear impact. This information may provide insight into injury mechanisms, occupant mathematical modeling, and aspects of seat and head restraint design. Low speed rear impacts using instrumented human subjects were conducted. Ten nominal 16 km/h closing speed car-to-car impacts were conducted using male and female subjects aged 22-54 years, with struck vehicle velocity changes of up to 10 km/h. Two head restraint conditions were studied. One was a standard seat integrated head restraint.

Considerable research has been conducted over the past decade on the response of both vehicles and occupants to low speed rear impacts. This research has employed various conditions of target vehicle braking and target occupant awareness. Relatively little effort has been devoted to quantitatively comparing vehicle and occupant responses under different braking and awareness. Given the variety of potential braking and awareness conditions in actual rear impacts, it is desirable to better understand the influence of these reactions on both vehicle and occupant dynamics. Low speed vehicle-to-vehicle rear end collisions were conducted with instrumented vehicles and an instrumented human subject. Six conditions were evaluated: 1) unaware occupant without braking, 2) aware occupant without braking 3) unaware occupant braking “normally”, 4) aware occupant full-braking, 5) unaware occupant with brakes mechanically fully applied, and 6) aware occupant with brakes mechanically fully applied.

Human volunteer kinematic response to low speed rear-end collisions was investigated. Nominal 16 kph (10 mph) car-to-car impacts were conducted, using human volunteers and anthropomorphic dummies. The human volunteers were both male and female, aged 27 to 58 years, with various degrees of cervical and lumbar spinal degeneration (documented by MRI scan) at the time of the tests. Human volunteer response was monitored and analyzed via accelerometers and high speed film. The impacts resulted in no injury to any of the human volunteers, and no objective changes in the condition of their cervical or lumbar spines. The results indicate a minimum injury tolerance to low speed rear-end impacts for males and females with various degrees of spinal degeneration. Kinematic responses of the head, mandible, upper torso and knees are discussed in light of existing theories regarding injury causation and tolerance.