Experimental evaluation of fatigue behaviour of thin Al5456 welded joints

Abstract

Because of wide applications of welded structures in different industries, using design codes and standards such as IIW recommendations is known as a safe and common method to design welded joints. The weld geometry and thickness of welded joint are the most important parameters that affect the fatigue strength of welded joints. In the present study, the fatigue behaviour of thin Al5456 butt‐welded joints has been investigated, and the effect of thickness on fatigue strength has been evaluated. Contrary to the above‐mentioned recommendations about thin welded joints, it was shown that the thickness of welded joints affects the fatigue strength. Moreover, the fatigue test results have been compared with the IIW design recommendations for three well‐known approaches in order to analyse the reliability of the codes. According to the design stress‐life diagrams, it was found that in some cases, the fatigue strength has much larger values than the IIW predictions, and IIW‐based design causes an over conservative design. While in some other cases, the fatigue strength is lower than IIW recommendations, and it leads to a non‐conservative design. Based on the experimental results, the new values for slope of S‐N curve and FAT have been proposed in order to improve the design diagrams.

Fatigue crack growth of Al 5083-H111 subjected to mixed-mode loading

“…In the second method, a series of Gaussian functions with four expressions has been used as data reduction method. The series is as follows [24]:…”

A frequency‐domain approach for damage detection in welded structures

“…However, as is well‐known, the fatigue strength of a welded component in presence of multiaxial cyclic loading is significantly lower than that of an unwelded one (even if the components are made of the same material) 2 . In particular, the factors causing the above strength reduction 3–5 are residual stresses, 6–9 thermal distortions, 10 defects caused by partial penetration, 11 and material microstructural imperfections 12 …”

Fatigue crack growth of butt welded joints subjected to mixed mode loading and overloading

“…All the aforementioned models have been proposed for nonwelded structures and their application to the welded joints has not been examined. As a result of plastic strains caused by local heating and cooling during the welding process, residual stress takes place affecting the fatigue crack growth of welded joints [25] and it should be taken into account in retardation models.…”