Simulation Model for Low-Speed Bumper-to-Bumper Crashes

Abstract

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. The output of the model for a numerical simulation is the acceleration vs. time information for each vehicle in the simulated crash. Three low-speed crash tests were performed and the dynamic IF-D curve was measured in each crash. The analytical model was used to simulate the three low-speed crash tests in order to demonstrate the model's ability to describe the vehicle dynamics in a crash that has already occurred. The model is also used to perform parametric studies that show how the structural characteristics of the vehicles' bumpers and the closing speed affect the crash pulse and to demonstrate a technique to estimate the maximum severity of a low-speed crash that has already occurred.

Impact characteristics of a vehicle population in low speed front to rear collisions

“…Nonetheless, the analysis shows for the first time that linear acceleration time models applied to both the loading and unloading phases of low speed rear impact yield closed form solutions which provide a close match to the available experimental data. Furthermore, although (Scott et al, 2010) found from a parametric modeling study that the overall pulse duration is independent of impact speed for fixed restitution and stiffness, they also found significant variations in overall pulse duration when restitution and stiffness are varied. In this paper it has been shown for the first time that the time to common velocity (T cv ), as opposed to the overall pulse duration, is substantially independent of collision closing speed for a set of full-scale staged collisions, and that T cv can therefore be used as an explicit surrogate measure of the normalised vehicle stiffness.…”

“…The recent work by (Scott et al, 2010(Scott et al, , 2012Bonugli et al, 2014;Funk et al, 2014) has shown that, when experimental knowledge of the combined bumper deformation behavior is known for a specific vehicle pair, the impact response for a specific collision can be found. However, the tests they completed showed non-linear and variable bumper stiffnesses, and the approach yields nontrivial errors in the coefficient of restitution.…”

“…As reviewed by Scott et al (2010Scott et al ( , 2012, these approaches have broadly followed either the differential equation approach (Thomson and Romilly, 1993;Ojalvo and Cohen, 1997;Ojalvo et al, 1998;Brach 2003;Scott et al, 2010Scott et al, , 2012 which require explicit definition of the effective stiffness of the two-vehicle system but which provide acceleration time histories, or a momentum energy restitution approach (Bailey et al, 1995;Cipriani et al, 2002;Happer et al, 2003) which does not require an estimate of vehicle stiffness, but consequently limits predictions to velocity change rather than acceleration time history.…”

Reconstruction of Low-Speed Crashes using the Quasi-Static Force vs. Deformation Characteristics of the Bumpers Involved in the Crashes

“…Previously, a simulation model was developed to recreate low-speed bumper-to-bumper crashes where the only damage was to the bumpers (1). The impact force used in this simulation model is directly related to the force-deformation (F-D) characteristics of the bumpers involved in the crash being investigated.…”

Comparative Study of Automotive Bumper with Different Materials for Passenger and Pedestrian Safety

“…The model is also used to compare that how the structural characteristics of the vehicles' bumpers and the closing speed affect the crash pulse and to demonstrate a technique to estimate the maximum severity of a low-speed crash that has already occurred [4].…”