Abstract
During the crack propagation process, the crack-branching behavior makes fracture more unpredictable. However, compared with the crack-branching behavior that occurs in brittle materials or ductile materials under dynamic loading, the branching behavior has been rarely reported in welded joints under quasi-static loading. Understanding the branching criterion or the mechanism governing the bifurcation of a crack in welded joints is still a challenge. In this work, three kinds of crack-branching models that reflect simplified welded joints were designed, and the aim of the present paper is to find and capture the crack-branching behavior in welded joints and to shed light on its branching mechanism. The results show that as long as there is another large enough propagation trend that is different from the original crack propagation direction, then crack-branching behavior occurs. A high strength mismatch that is induced by both the mechanical properties and dimensions of different regions is the key of crack branching in welded joints. Each crack branching is accompanied by three local high stress concentrations at the crack tip. Three pulling forces that are created by the three local high stress concentrations pull the crack, which propagates along with the directions of stress concentrations. Under the combined action of the three pulling forces, crack branching occurs, and two new cracks initiate from the middle of the pulling forces.
Highlights
IntroductionIn the crack propagation process, a crack may split into two or more branches
Cracks are the main drivers of material failure [1,2]
Since the strength mismatches on both the left and right sides of the crack are different in this kind of model, the results demonstrate that the similar strength mismatch on each side of the crack, which is mentioned in Section 5.1, is a sufficient but not necessary condition for crack branching
Summary
In the crack propagation process, a crack may split into two or more branches. This crack-branching phenomenon usually occurs in concrete structures, brittle materials, and quasi-brittle materials under dynamic loading, and it makes the fracture become more unpredictable and has aroused a wide range of concerns. Investigated the crack propagation behavior in concrete and rock-like materials under dynamic tensile loading by an optical correlation technique. Ožbolt et al [5,6,7] studied the inertia on resistance, failure mode, and crack pattern of concrete loaded by higher loading rates. Mecholsky et al [9] studied the relationship between fractography, fractal analysis, and crack branching in brittle materials. Chen et al [11] studied the influence of micro-modulus functions on peridynamics
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