Abstract
J-resistance curve of ductile material is important to describe the ability of a crack structure or material to resist fracture. Experimental and theoretical methods are developed to obtain J-resistance curve of metallic material. However, there are rare reports to predict J-resistance curve directly by tensile test on ductile materials. In this paper, an analytical method is proposed to predict the J-resistance curve for metallic material. Based on a new method, true stress-strain curve up to failure of ductile material is obtained. Thus, fracture threshold in different constrains are calculated using different kinds of specimens. A simple logarithmic-relationship between σ1f and σ*f (Yao-Cai criteria) is proposed. The new fracture criterion and full-range constitutive relationship are then used to describe the fracture behaviour near the crack tip. Stress triaxiality and critical fracture first-principle stress around crack tip are obtained. Therefore, fracture procedure is divided into two parts: crack tip blunting and steady crack growth. The relationship of J-integral and crack growth amount R is established respectively according to the blunting line equation and HRR stress field. The predicted results for test specimens (CT, SENT, CIET) with different initial crack length of the A508-3 steel coincide well with the test results. The results show that stress triaxiality at crack tip is a typical characteristic feature following the constraint effect and the Yao-Cai criteria is recommended for the fracture threshold of ductile material.
Published Version
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