Experiment and Numerical Study on the Influence of Different Loading Conditions on the Fracture Force of Tension Bolts

초록

As a triggering system, the tension bolt will be equipped with a mechanical fuse, which protects the train passengers, drivers and primary structures in the event of a low-speed collision accident. The tension bolts are broken in a controlled manner under the dynamic loading condition. In this paper, impact tests for the tension bolts with and without pretension, and a quasi-static test without pretension have been performed to validate the effects of the strain rate and the pretension caused by fastening the bolt. The influence of moment on the fracture force is studied using FEM analysis. The pretension and fracture force of the bolt are measured using the strain gages and dynamic strain gages, respectively. A fracture analysis of the tension bolt using FEM code has been performed with the GTN (Gurson, Tvergaard and Needlemann) damage model to predict precise fracture forces. The results from the tests and the FEM analyses show that the fracture force increases with an increase in the strain rate, but the pretension and moment do not affect the fracture force. The results of the FEM analysis with GTN damage model appear to be in good agreement with the test results.