Application of Lateral Pole Impact Force-Displacement Data to the Reconstruction of Side Impacts with Narrow Objects

Reconstruction of passenger vehicle accidents involving side impacts with narrow objects has traditionally been approached using side stiffness coefficients derived from moveable deformable barrier tests or regression analysis using the maximum crush in available lateral pole impact testing while accounting for vehicle test weight. Current Lateral Impact New Car Assessment Program (LINCAP) testing includes 20 mph oblique lateral pole impacts. This test program often incorporates an instrumented pole so the force between the vehicle and pole at several elevations along the vehicle - pole interface is measured. Force-Displacement (F-D) characteristics of vehicle structures were determined using the measured impact force and calculated vehicle displacement from on-board vehicle instrumentation. The absorbed vehicle energy was calculated from the F-D curves and related to the closing speed between the vehicle and the pole by the vehicle weight.

The presented approach resulted in approximately a 2% underestimation of closing speed in large four-door sedans and approximately a 9 to 10% underestimation in large four-door pickup trucks. Accounting for structural restoration is important when assessing accident severity using this methodology. The nominal restoration of the vehicle structures was generally calculated to be in the 17 to 21% range. Furthermore, comparison of F-D curves between vehicle classes and different elevations on a given vehicle is useful for assessment of field crashes, which can occur in various orientations.