Development of an Impact Pendulum for Use in Collinear, Low-Velocity Front-to-Rear Crash Tests

The costs of low-velocity, front-to-rear crash tests include the bullet (striking) and target (struck) cars. Analyses of this type of tests led us to conclude that it may be technically feasible and economically advantageous to replace the bullet car with a simplified mechanical device. A bifilar pendulum with an impact face consisting of a mass-spring-damper system was designed to simulate the bullet car in car-to-car, collinear, low-velocity (delta-v <= 8 km/h) front-to-rear tests. The elements of the pendulum face were evaluated dynamically and quasi-statically. Also, car-to-car tests were initially performed with stationary target cars (brakes off). Repair or replacement of the minor damage observed in the cars was accomplished as needed. Tests were subsequently performed with the pendulum striking the same target cars and approximating the bullet cars' impact energies. The pendulum, bullet, and target cars were instrumented with translational acceleration and velocity sensors. A BioRID IIg Anthropomorphic Test Device (ATD) instrumented with neck and thoracic load cells, and head and spine accelerometers was used in the driver seat of each of the target cars. High-speed photography was used to measure the motion of the pendulum and cars in all the crash tests. The loads and accelerations measured within the ATD, and accelerations of the target car were compared between the car-car and pendulum-car tests. The results show that within the delta-v range tested, the longitudinal accelerations of the target car in the car-car tests were similar to those measured in the pendulum tests. The loads and accelerations measured within the ATD were also similar between the car-car and pendulum-car tests. Due to the motion of the bifilar pendulum, there were some minor differences in the vertical accelerations of the target cars. Nevertheless, for the delta-v range and the cars used in this test series, the authors conclude that the pendulum impact device provides an adequate simulation of the mechanical dynamics of the bullet car, and may be used to reduce costs in some low-velocity, car-to-car tests.