Analysis Of 3D Cracks In An Arbitrary Geometry With Weld Residual Stress

Materials containing flaws like inclusions and lack of weld fusion can cause cracks to form and grow; a critical size crack can cause a catastrophic fracture failure, even at low stress. Fracture mechanics allows cracks to be evaluated as benign or requiring repair. Modeling the actual crack location in a complicated geometry is necessary to obtain accurate crack stress intensity values, crucial in a thorough crack evaluation. When existing stress intensity solutions are not available, FEA of 3D cracks provides a way to compute the stress intensity. A method for quickly generating 3D crack meshes within an arbitrary shape volume is needed to efficiently compute the stress intensity. This method uses a mesh of brick elements to define the arbitrary shape volume around the crack in the structure. The 3D crack mesh is generated within the definition mesh and inserted into the larger model; the meshes are connected by bonded contact. For a crack in a weld, the residual stresses can be included by mapping all stress components from an uncracked model onto the crack mesh as an initial stress. The weld residual stress increases the stress intensity. The stress intensity is computed using ANSYS results during post-processing.

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