• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2020, Vol. 56 ›› Issue (24): 72-80.doi: 10.3901/JME.2020.24.072

Previous Articles     Next Articles

Research on Fracture Mechanism and Prediction of High-strength Steel Sheet under Different Stress States

Lingyun QIAN1,2,*(), Wanting JI1,2, Xiaocan WANG1,2, Chaoyang SUN1,2, Tengyun MA1,2   

  1. 1 School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083
    2 Beijing Key Laboratory of Lightweight Metal Forming, Beijing 100083
  • Received:2020-02-26 Online:2020-12-20 Published:2021-02-05
  • Contact: Lingyun QIAN E-mail:qianly@ustb.edu.cn

Abstract:

The macroscopic fracture behavior of metal sheet forming process highly depends on microscopic fracture mechanism, thus establishing a ductile fracture criterion reflecting effects of fracture mechanism could ensure high forecast precision of fracture behavior. The forming processes under various stress states of advance high-strength steel TRIP780 sheet is tested and simulated. Five fracture tests ranging from shear to tension stress states are conducted and the parallel numerical simulations are also performed. The scanning electron microscope(SEM) fractographies of fracture surfaces are detected to reveal microscopic fracture mechanism. The normal stress and shear stress are obtained to correct with the evolution rule of fractographies and therefore are deemed as parameters which can describe fracture mechanism. Therefore, MMC fracture criterion is characterized by normal stress and shear stress is adopted and then extended to predict fracture behavior of in-plane compression-shear forming. The results indicate that the MMC fracture criterion reflecting fracture mechanism of TRIP780 sheet could predict fracture of forming processes under wide stress state range covering form compression-shear to tension-shear, which further proves the superiority of calibrated MMC fracture criterion.

Key words: high-strength steel, stress state, fracture mechanism, MMC fracture criterion, in-plane compression-shear forming

CLC Number: