Impact Pull-Out Fracture of Steel Plates Jointed by Bolt

Abstract

Collision safety and reliability of cars under impact loading become more and more important in the vehicle industries. This study is concerned with the development of a fracture criterion for the impact fracture of jointed steel plates of a bolted joint used in a car body, which may contribute to crash simulations by computer-aided engineering (CAE). The impact behavior and fracture of jointed steel plates of a bolted joint were examined by experiments and numerical simulations. The impact pull-out test of jointed steel plates by a bolt was performed by making use of an one-bar method for impact tests, together with the static test using a universal testing machine INSTRON 5586. In order to understand the mechanism of fracture process of the jointed steel plate, numerical simulations by FEM code ANSYS and LS-DYNA were also carried out. The rupture of steel plates jointed by a bolt with washers occurred along the circular outside of washers and made a hole with the same diameter as washers for both of static and impact loading conditions, and then the pull-out load (F) increased with increasing of the diameter of washers. On introducing the pull-out stress defined as (F/A) for convenience, in which A is the cross-sectional area of the steel plate along the circumference of a washer, the pull-out strength showed almost the same value regardless of the washer size. This result suggests that a stress-based fracture criterion may be developed for the impact fracture of jointed steel plates of bolted joint used in a car body.