Research of non-linear frictional contact model in vehicle-pedestrian accidents based on computer simulation

Abstract

In numerical simulation of vehicle–pedestrian accidents, pedestrian rest positions are greatly influenced by the friction coefficient between pedestrian and ground. Current researches on vehicle–pedestrian accident reconstruction often regard pedestrian–ground friction coefficient as a constant value. However, clothing fabric belongs to viscoelastic material. Some researches show that friction coefficient of viscoelastic material can be influenced by normal contact force. In this paper, a contact model between clothing fabric and asphalt road is built by computer simulations. The calculation based on this contact model indicates that the pedestrian–ground friction coefficient in accidents is not constant. Relationship between friction force and contact pressure is non-linear. Meanwhile, according to the simulation results of a real-world vehicle–pedestrian accident, influence of vehicle– pedestrian contact stiffness on pedestrian projection has been discussed, and simulation errors under different pedestrian–ground friction coefficients are calculated. Simulation results show that compared with traditional pedestrian–ground contact model, the non-linear pedestrian–ground contact model can obtain smaller simulation error with higher stability, which has validated the rationality of this contact model.AbbreviationsShear stress at surface contact pointsAReal contact areaRMS roughness of the surfaceConstant related to the average height of the surfaceCorrelation length of the surface in X-directionCorrelation length of the surface in Y-directionZ1Height matrix of surface 1Z2Height matrix of surface 2Average height of peaks on surface 1Average height of peaks on surface 2Distance between two rough surfacesCharacterised distance between rough surfacesDistance matrix between rough surfacesRatio of real contact area to nominal contact areaGaussian contact radiusReal contact area of a single rough peakAccuracy of contact area calculationContact matrix between rough surfacesLocal contact force of a single rough peakElastic modulus of surface 1Elastic modulus of surface 2Poisson ratio of surface 1Poisson ratio of surface 2Friction forceFriction coefficientFeature friction coefficientConstant related to material property parameters