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The purpose of this study was to develop a numerical analytical model of collinear low-speed bumper-to-bumper crashes and use the model to perform parametric studies of low-speed crashes and to estimate the severity of low-speed crashes that have already occurred. The model treats the car body as a rigid structure and the bumper as a deformable structure attached to the vehicle. The theory used in the model is based on Newton's Laws. The model uses an Impact Force-Deformation (IF-D) function to determine the impact force for a given amount of crush. The IF-D function used in the simulation of a crash that has already occurred can be theoretical or based on the measured force-deflection characteristics of the bumpers of the vehicles that were involved in the actual crash. The restitution of the bumpers is accounted for in a simulated crash through the rebound characteristics of the bumper system in the IF-D function.

Though rotation is thought to be the most common mechanism of foot and ankle injury in both automobile crashes and in everyday life, axial impact loading is considered responsible for most severe lower extremity injuries. In this study, dynamic axial impact tests were conducted on 92 isolated human lower limbs. The test apparatus delivered the impact via a pendulum-driven plate which intruded longitudinally to simulate the motion of the toepan in an automobile crash. Magneto-hydrodynamic (MHD) angular rate sensors fixed to the limbs measured ankle rotations during the impact event. Malleolar or fibula fractures, which are commonly considered to be caused by excessive ankle rotation, were present in 38% (12 out of 32) of the injured specimens. Ankle rotations in these tests were always within 10° of neutral at the time of peak axial load and seldom exceeded failure boundaries reported in the literature at any point during the impact event.

It has been proposed that low speed collisions in which the damage is isolated to the bumper systems can be reconstructed using data from customized quasistatic testing of the bumper systems of the involved vehicles. In this study, 10 quasistatic bumper tests were conducted on 7 vehicle pairs involved in front-to-rear collisions. The data from the quasistatic bumper tests were used to predict peak bumper force, vehicle accelerations, velocity changes, dynamic combined crush, restitution, and crash pulse time for a given impact velocity. These predictions were compared to the results measured by vehicle accelerometers in 12 dynamic crash tests at impact velocities of 2 - 10 mph. The average differences between the predictions using the quasistatic bumper data and the dynamic crash test accelerometer data were within 5% for bumper force, peak acceleration, and velocity change, indicating that the quasistatic bumper testing method had no systematic bias compared to dynamic crash testing.