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The objective of this paper is to examine automobile bumper systems in aligned low-speed impacts and provide data which correlate compression of bumper systems with the vehicle impact severity. A significant number of automobile collisions involve bumper-to-bumper contact at speeds which produce little or no permanent vehicle damage. Contemporary bumper systems predominantly consist of a fascia and impact beam, which span the vehicle width, and some form of impact absorber. A common impact absorber is the shock-absorber-type isolator. Foam cores, deformable steel struts, rubber shear blocks and leaf springs also exist. Data from 58 vehicle-to-barrier and 136 vehicle-to-vehicle aligned impacts are presented. Impact duration, speed change, isolator compression, and coefficient of restitution results are presented and discussed. Static and dynamic compression tests on several isolators have been carried out.

There are many bumper-to-bumper automobile collisions in which a vehicle occupant claims injury but where there is little or no outward damage to the vehicles. On vehicles equipped with shock-absorber-type bumper isolators, the only “damage” often consists of compression marks left on the isolator piston tube and scuffs on the bumper. This paper examines the behavior of specific automobile bumpers in aligned low-velocity collisions. Specifically, empirical data gathered during numerous (currently 660) vehicle-to-vehicle and vehicle-to-barrier collisions are presented and relationships between isolator compression and vehicle impact severity are developed. General trends among all types of isolators and trends specific to vehicle manufacturers are identified and discussed. Damage threshold data are also presented.

Front, rear, lateral and side-swipe collisions were staged to correlate passenger vehicle damage to motion. Data from the staged collisions are used to develop severity-prediction methods for the four collision types. Human volunteers were present in many of the vehicles tested. Their responses, and the responses of human volunteers to staged impacts in other studies, are discussed in terms of impact severity. For front and rear impacts, data are presented that correlate the post-impact condition of bumper systems to impact severity. These data build on data previously presented1,2,3. A method for computing velocity change (ΔV) for vehicle to vehicle collisions from vehicle to barrier data is presented. Data from staged low-speed lateral collisions correlate target and bullet vehicle damage to linear and angular velocity change (ΔV, Δω), impact location, pavement friction and collision force.

Five collisions were staged in order to evaluate PC-Crash, a simulation program used for investigating motor vehicle collisions. Both vehicles were moving in all of the staged collisions at 1:1 or 2:1 speed ratios. Pre-impact speeds ranged from 19 to 56 km/h. Two separate methods were used to test the validity of the simulation program. Firstly, collision parameters were calculated from measured data, and used as input to the PC-Crash collision model. Secondly, the post-impact vehicle paths and rest positions were used to determine the pre-impact speeds. There was agreement between measured and simulated collision dynamics. Using the PC-Crash "Optimizer" to reconstruct the five collisions, the error in calculated pre-impact speeds of the ten vehicles ranged from-3.3 to +4.1 km/h. Vehicle speeds were determined based on post-impact rotation and paths, without detailed information on the braking from each wheel or the actual collision coefficient of restitution.