Research on Welding Structure with Transition Changing Faces at Cylinder Block on Boom of Medium Excavator by Means of Hot Spot Stress Approach

To investigate the cracking reason in welding structure with transition changing faces at cylinder block on boom of medium excavator during fatigue test, the finite element model of boom was established by using ANSYS finite element software. The stress distribution of the boom was obtained under fatigue loading spectrum of medium excavator. In addition, the fine model of welding structure with solid element length 2 mm was set up with the help of sub-model technology in ANSYS software to get the accurate hot spot stresses around welding toes. Finally, the fatigue life of this welding structure was calculated according to IIW fatigue class. The results show that the stress gradient along with the thickness direction can be acquired by fine three-dimensional finite element sub-model of welding structure. Therefore, the weakest point in thick plate was located, which was in accordance with the experiment result.