Pure mode II fracture analysis of dissimilar Al-Al and Al-Cu friction stir welded joints using the generalized MTS criterion

Abstract

Aluminum and copper, two highly desired material, are the most consumed minerals in different industries after iron and two most important materials in today’s industrial world. Copper for its beneficial properties like thermal and electrical conductivity and resistance to corrosion and aluminum for its low weight along with high strength are used extensively especially in the aerospace industry. Newly advanced friction stir welding (FSW) made these two materials with low weldability to be connected well together. In this study, mode II fracture of dissimilar friction stir welded joints made of AA7075-T6 and AA6061-T6, which are very popular in the aerospace industry, and also AA7075-T6 to copper are investigated by means of the cracked semi-circular bending (CSCB) specimen. According to ductility nature of the welded joints and formation of the substantial plastic zone around the crack tip at the crack growth instance, a study of failure requires elastic-plastic fracture mechanics. Since these criteria are intricate and laborious, a new approach is therefore needed to overcome this problem. A different approach to the traditional problem is given in the Equivalent Material Concept (EMC). By merging the EMC with the Generalized maximum tangential stress (GMTS) criterion (a brittle fracture criterion), the ultimate load of the friction stir welded of CSCB specimens is estimated. Theoretical results go beyond experimental reports, showing that the proposed criteria could meticulously predict the load carrying capacity (LLC) of the CSCB specimens.