Investigation of strength mis-match effect on elastic plastic fracture parameters in laser beam welded aluminium alloy joints using the finite element method

Abstract

In this study, elastic plastic fracture toughness parameters of laser-welded 6013 aluminium alloy are investigated. For this purpose, compact tension specimens used in the experimental study are modelled using the finite element software. In the analyses, crack tip opening displacement ( δ5) and J-integral values are determined and crack tip opening displacement, δ5 and J-integral resistance curves (R-curves) are generated. Crack tip opening displacement, δ5 resistance curves are compared with those obtained from the experimental work, and J-resistance curves are compared with those obtained from formulation. Effect of weld strength undermatching on crack tip opening displacement, δ5 and J-resistance curves is discussed. δph values obtained by the plastic hinge method are compared with the crack tip opening displacement, δ5 values. Fracture toughness parameters obtained from the finite element analysis showed a good agreement with those obtained from the experimental work and formulation. It is observed that the resistance curves obtained using the crack tip opening displacement, δ5 and J-integral characterize the resistance of the material against crack growth in a similar manner, and strength undermatching decreases the fracture resistance. The relationship between δph and crack tip opening displacement, δ5 is nonlinear, and as crack tip opening displacement increases, crack tip opening displacement, δ5 becomes larger than δph.