For the cylinder block main bearing thread fatigue strength analysis and cracking failure problem,a virtual simulation model was established based on the fatigue test of the main bearing wall of cylinder block,and the stress distribution of the main bearing wall was calculated.On this basis,the refined main bearing threaded coupling sub-model was established by re-gridding the cylinder block with the fatigue test results of the main bearing wall.The fatigue strength model of main bearing threads was established based on the critical plane method and Haigh diagram,considering the effects of stress gradient,average stress and surface roughness.And fatigue strength evaluation and failure mechanism analysis were carried out.The results show that the safety factor of the first few buckles of the main bearing thread and bolt coupling gradually increases under the influence of the average stress generated by the bolt preload.The safety factor at the last buckle position is the smallest at 0.8,which matches the cracking position in the test.And the cracking is caused by the simulated gas force dominated stress amplitude which exceeds the material and structural bearing capacity.
关键词
主轴承螺纹/子模型/安全系数/疲劳失效/疲劳试验
Key words
main bearing thread/submodel/factor of safety/fatigue failure/fatigue test
维普
万方数据