| Arm is one of the key components of an excavator working device, the structure safety performance and life of which directly affects the whole machine’s performance. As the strength analysis of arm without considering the affection of cracks, appeared in the structure, on the strength and lifetime, this article, employing the finite element method, studies the stress intensity factors of crack border of the arm with cracks, and makes an analysis on the cracks’effects. The main research contents are as follows:According to the needs of the research purposes, the modeling method of finite element analysis was applied. This paper, using the sub-model method combined shell solid hybrid modeling analysis method, has carried a finite element analysis on the arm under the dangerous working conditions to understand the distribution of stress and strain. The results show that the result of sub-model analysis is consistent with that of the overall analysis. Three-dimension solid model with cracks was established based on the sub-model, to achieve the research on Stress Intensity Factors of the crack front under real load.This paper, after analyzing the common initiation forms of welding crack, based on solid sub-model, establishes a Three-dimension solid model of the T unilateral fillet weld with surface crack defects, and studies the variation of different types stress intensity factors as the crack on different places, such as the weld toe at web, the weld toe at wing and ripple. As board may contain rolling defects, this paper, treating the base plate as the research object, studies the variation of different types stress intensity factors at different angles, sizes and free surface of surface crack. Through these studies, the variation of different types stress intensity factors of the cracks at different parts was obtained and the damage mechanisms of the surface cracks on the arm was revealed.With SWE230excavator as the experiment platform, the stress testing experiment on the arm proves the correctness of the finite element analysis model and results, which also indirectly proves the accuracy of the boundary conditions in the analysis of the stress intensity factors of crack front. |
