Effect of blowholes on fatigue crack initiation life of aluminum alloy lap-joint

Blowhole (BH) contained in weld joints is known to be a cause of reduction in strength. Concerning the effect of BHs to fatigue performance of weld joints, their total number or volume are conventionally used for the mechanical design, since the available data are limited by the measuring precision and their costs. In other words, the mechanical design would be improved if the individual size or position of the BHs could be precisely determined since it would lead to a better knowledge of the material performance and therefore to a more precise maintenance of the welded components. The purpose of this study is to develop a fatigue performance evaluation method for aluminum alloy joints considering the effect of BHs. Several FE models of lap welded joints, with different BH distributions, were generated to simulate the BH effects under fatigue loading. The material model adopted for FE analyses is based on an unconventional plasticity model, calibrated to reproduce the cyclic plasticity...