Abstract
Welding is used to realize permanent assembly in mechanical structures to assure the continuity of the parts to be assembled contrary to the other assembly techniques which have physical or chemical discontinuities. Generally, crack evolution depends on several intrinsic and extrinsic parameters of material. The aim of this work is to analyse the severity of crack defects on the mechanical behaviour of Welded joints. The cracks are considered located in the weld metal. The J-integral method was used to analyse the fracture behaviour of these structures by the two-dimensional finite element method using Cast3M code. The effect of the mechanical properties, the mismatching and the crack size on the J-integral values was highlighted. A good correlation between the FEM simulations and the literature analysis results was observed. We note that the loading mode affects directly the J-integral value and consequently on the mechanical behaviour of the weldment.
Highlights
Welded structures always contain inherent defects even when no errors are made in selecting the correct combination of materials, joint design or welding processes[1,2]
A number of finite element analyses (FEA) was performed initially for one case taken from the past work of Rodrigues[27]
We have examined the opening mode and the mixed mode to evaluate the J-integral for the study of a welded joint formed by the weld metal and the base metal
Summary
Welded structures always contain inherent defects even when no errors are made in selecting the correct combination of materials, joint design or welding processes[1,2]. When fusion welding is employed in fabrication, the highly non-uniform temperature field near the weld pool introduces large plastic strains in the solidified weld metal and in the heat affected zone (HAZ)[3]. Apart from the presence of various defects, the inhomogeneous material composition produced a non-uniform deformation field naturally complicates the predictions of material reliability of the resulting weld-base metal composite. For many engineering applications, in nuclear systems, the more appropriate fracture mechanics techniques are imperative for obtaining the material crack growth resistance parameter[4]. As a parameter characterizing crack tip field, the J-integral has played an important part in elasticplastic fracture mechanics and assessment of homogenous structure[5,6,7]. When J-integral concept is used in welded joints, the situation is much more complicated due to the existence of mechanical heterogeneity. The most commonly used specimens include the Arcan test fixture and specimen[16,17,18]
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