Truck and Sport Utility Vehicle Front End Stiffness Corridors 2018-01-0518

The purpose of this study was to characterize front stiffness response of contemporary sport utility vehicles (SUVs) and trucks. Vehicle front impact test data were obtained from data published by the National Highway Traffic Safety Administration [NHTSA]. For all tests, force data were obtained from barrier load cells and stroke data were derived from accelerometers. Data from 53 truck and SUV tests were aggregated by vehicle product segment according to body style to obtain mean ± standard deviation (SD) stiffness corridors: (1) compact unibody SUV/crossover, (2) small unibody SUV/crossover, (3) mid-size unibody SUV/crossover, (4) frame SUV, and (5) frame truck. To compare between vehicle product segments, this study also considered the average stiffness (slope) within the stroke region required to achieve 300 kN total barrier force. Across unibody SUV segments, average stiffness varied from 1.4–1.8 kN/mm. Stiffness of frame SUVs and trucks was up to 93% higher than stiffness of unibody SUVs (2.7 vs. 1.4 kN/mm). Observed differences in stiffness corridors may have been due in part to unibody SUV design differences. For example, additional stroke (structure) was observed forward of the front axle comparing an exemplar mid-size SUV and frame SUV. In some cases, this structure may include a low stiffness bumper absorber. When stiffness corridors were offset to simulate a low stiffness initial geometry, better agreement between mean stiffness corridors was observed across vehicle segments. As unibody SUVs may continue to replace frame designs, future work should confirm directly the reasons for this stiffness difference in vehicle segments.