Fatigue Performance Analysis Of Aluminium Welded Joints Based On Mesh-Insensitive Structural Stress

Welding is the main connection method in the engineering and the fatigue damage of welded structure has obvious local characteristics, it often show that the welded joints are the main reason of fatigue failure for welding structure. Nowadays, aluminum alloy welded structure has been more widely used in the equipment manufacturing sector; the fatigue analysis of Aluminum alloy welded joints is one of the important basic content of welded structure fatigue design. This topic is supported by the national natural science fund project:"based on welded structure fatigue design and basic research of Mesh-Insensitive Structural Stress"(No:51175054), analysing the influencing factors of3A21,5A06and6061Aluminum alloy welded joints fatigue performance by Mesh-insensitive structural stress method.This paper focused on the following research:Firstly, the paper discussse the using situation of welding structure, history of fatigue, the reason of fatigue failure for welding structure and analyses the fatigue characters of the welded structures. Furthermore, the main methods applied to the analysis of the welded structures are introduced, sush as the nominal stress method, the hot stress method, the fracture mechanics method and the Mesh-insensitive structural stress method which is introduced in detail.Secondly, according to the test parameters of65aluminum alloy joints, the finite element model is established and the same as the test loading condition is loaded to solve. Besides, the fatigue performance and influence factors including the stress ratio, thickness, material, joint type, correction function of3A21,5A06and6061aluminum alloy welded joints is analyzed by seven kinds of solutions.Finally, the difference of fatigue influence factor is compared by the nominal stress and structural stress. The results show that, the structural stress can preferably represent the effect of the different factors for the fatigue performance of welding joints than the traditional nominal stress methods; when the equivalent structural stress characterizes the S-N data, a main S-N curve can be obtained, which accords with the requirements of fatigue design.