Abstract
The stress state has an important effect on the deformation and failure of metals. While the stress states of the axisymmetric notched bars specimens are studied in the literature, the studies on the flat metal specimen with inclined notch are very limited and the stress state is not clearly characterized in them. In this paper, digital image correlation and finite element simulations are used to study the distribution of strain and stress state, that is stress triaxiality and Lode angle parameter. Flat specimen with inclined notch was tested to extract the full field strain evolution and calculate stress state parameters at three locations: specimen centre, notch root and failure starting point. It is found that compared with the centre point and the notch root, the failure initiation point can better characterize the influence of the notch angle on the strain evolution. Conversely, the centre point can more clearly characterize the effect of the notch angle on stress state, since the stress states at the failure point and the notch root change greatly during the plastic deformation. Then the calculated stress state parameters of the flat metal specimen with inclined notch at the centre point are used in Wierzbicki stress state diagram to establish a relationship between failure mode and stress state.
Highlights
The deformation and failure mode of metals are not related to the material itself, and related to the stress state they endure
They found that void growth was the main failure mode under high stress triaxiality, while under low stress triaxiality, the crack developed in the way of combined shear and void growth modes, and in the negative stress triaxiality, the fracture was controlled by shear only
In order to examine the critical strain at different stress states, Kiran [9] and Liu [10] carried out micromechanical analysis and proposed that the critical strain was a non-monotonic function with stress triaxiality
Summary
The deformation and failure mode of metals are not related to the material itself, and related to the stress state they endure. Besides notched round bar specimen, notched flat specimen is another important one to understand the effect of stress state on the mechanical and failure behaviour. Since a wide range of stress triaxiality and Lode angle parameters can be achieved by changing the notch angle and notch size of the notched flat specimens, it is convenient to study the stress state on mechanical and failure behaviour of metals. There are very limited reports on the effect of the Lode angle parameter on the failure behaviour of flat metal specimen with inclined notch. Digital image correlation (DIC) and finite element simulation (FES) are used to characterize the stress state of flat metal specimen with inclined notch and analyse the influences of stress triaxiality and Lode angle parameter on the failure mode
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