Low Speed Collinear Impact Severity: A Comparison Between Full Scale Testing and Analytical Prediction Tools with Restitution Analysis

Low speed collinear collisions have received some attention in the past in published technical literature. Underrepresented are full-scale instrumented tests utilizing vehicles equipped with foam core bumpers and closing speeds greater than 2.2 meters per second (m/s). Systematic testing was designed to obtain data in collisions between vehicles with similar and mixed bumper structures. Testing was performed at closing speeds ranging from 0.8 to 5.4 m/s. Following each test, vehicle bumper and other damage was documented. Data from the 30 tests for each category of bumper and mixed categories were analyzed to identify the test speed, load magnitude, velocity change, duration of impact and coefficient of restitution. In addition, the energy absorption characteristics and damage thresholds of the various types of bumper systems were obtained. The coefficient of restitution was analyzed as a function of closing speed, velocity change, impact duration, bumper type, and other parameters and compared to previously published data and equations. A modified momentum-energy-restitution (MER) method was also used to calculate predicted vehicle response for each test and compare it to the actual test results.