Welded Steel Fatigue Theory And Experimental Research

The Fatigue damage is one of the most common failure mode in mechanical structure .According to relevant data, 50% ~ 90% failures of mechanical products are caused by fatigue damage. However, plastic deformation of steel structure will not appear obviously before Fatigue damage. It usually suddenly fractures without any obvious signs, which may cause extremely heavy accident. With the development of society and technology as well as the increasing requirements of products' safety features, the safety performance has become an important indicator to judge the products .Along with the formation of the international market and the increasingly fierce competition, the ability that whether the enterprises can produce high safety products has become a decisive factor to decide a company's survival and prosperity.This paper reviews the history of study in fatigue phenomenon, current situation and the development tendency. Besides, it introduces the most commonly used related theory in the study of fatigue, including the S-N curve, the fatigue accumulated damage theory, the initiation and expansion of fatigue crack , and the commonly used methods in estimating fatigue life . This thesis is mainly concerning with the force analysis of the common welded steel structure, welding strander beam and welding box beam. Beside, it also predicts the location of fatigue damage by means of virtual analysis software. And then, It makes a fatigue test on this two kinds of welding steel structure by using of MTS Hydraulic program-controlled servo fatigue test loading system, which affirms the former prediction as well as finds the weakness of design that is instructive to the design of steel structure .compared with the provisions in the book of steel structure design code GB50017-2003, it validates rationality of the design.