A numerical framework of the phenomenological plasticity and fracture model for structural steels under monotonic loading

Qun He , Michael C.H. Yam , Zhiyang Xie , Xue-Mei Lin , Kwok-Fai Chung

Abstract

In this study, the classical J2 flow theory is explicitly proved to be inappropriate to describe the plastic behaviour of structural steels under different stress states according to the reported test results. A numerical framework of the characterization of the strain hardening and ductile fracture initiation involving the effect of stress states, i.e., stress triaxiality and Lode angle parameter, is proposed based on the mechanical response of structural steels under monotonic loading. Both effects on strain hardening are determined by correction functions, which are implemented as different modules in the numerical framework. Thus, other users can easily modify them according to their test results. Besides, the ductile fracture initiation is determined by a fracture locus in the space of stress triaxiality, Lode angle parameter, and fracture strain. The numerical implementation of the proposed model and the corresponding code are provided in this paper, which are also available on GitHub. The validity of the numerical procedure is examined through single element tests and the accuracy of the proposed model is verified by existing test results.

Key Words

ductile fracture; lode angle parameter; strain hardening; stress triaxiality; structure steels

Address

Qun He — 1)Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China 2)Chinese National Engineering Research Centre for Steel Construction (Hong Kong Branch), The Hong Kong Polytechnic University, Hong Kong, China
Michael C.H. Yam — 1)Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China 2)Chinese National Engineering Research Centre for Steel Construction (Hong Kong Branch), The Hong Kong Polytechnic University, Hong Kong, China
Zhiyang Xie — State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China
Xue-Mei Lin — 1)Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China 2)Chinese National Engineering Research Centre for Steel Construction (Hong Kong Branch), The Hong Kong Polytechnic University, Hong Kong, China
Kwok-Fai Chung — 1)Chinese National Engineering Research Centre for Steel Construction (Hong Kong Branch), The Hong Kong Polytechnic University, Hong Kong, China 2)Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China

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