Study on Damage Morphology and Stress Distribution on Engine Spacer Surface
The influence of two kinds of damage on the surface of engine spacer,pit and scratch,on the stress distribution is investigated,and fatigue tests are carried out to evaluate the reliability of the spacer with preset damage.The results show that when there is a pit damage on the surface,the stress concentration increases with the ratio of long and short half-axis of the pit ellipse,and when the ratio of long and short exceeds 2,the stress tip would be generated,and it decreases significantly with the decrease of the incidence angle,however,the response of stress to the change of pit depth is weaker;when there is a scratch damage on the surface,the stress concentration increases significantly with the increase of scratch depth,and the stress has exceeded the fatigue strength limit of the material when the scratch depth is 0.4mm.The stress has exceeded the material fatigue strength limit at 0.4 mm scratch depth,and the stress decreases significantly when the incidence angle decreases.In addition,the fatigue fracture occurred in the heat-affected zone near the weld for both damage patterns,and no engineering detectable cracks were found in the preset damage zone.
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