Experiments and finite-element-method analyses for mechanism of structural hysteresis of the vehicle body

Abstract

In order to clarify the mechanism of the vehicle body hysteresis affecting “rigidity feeling”, one of the driver's sensory evaluation in the driving test, the influence of friction acting on spot welding flanges on hysteresis, which is drawn by the displacement-load diagram of double-hat-shaped parts assembled by spot welding under static or relatively slow deformation, is experimentally and numerically evaluated. The hysteresis of two specimens, one has the contact around R-tangent of flanges and the other has it around edge, are compared and it is confirmed that the former type has larger hysteresis than the latter. The hysteresis is evaluated by the friction loss which is energy dissipation generated only by friction on the surfaces of the spot welding flanges. The loss calculated by the finite-element-method (FEM) with the contact and friction between two flange surfaces opposing each other has good agreement with that measured by the experiment. Additionally, by studying the detail of the relative slip and friction force distribution on the surface of two flanges obtained by the FEM analyses, the difference in hysteresis of two specimens and the cause of the friction loss are discussed.