Quantitative inversion of bolt fatigue fracture based on Paris formula and finite element verification
Accurate prediction of bolt fatigue life is very important to guarantee the engineering safety and draw up the maintenance plan.Paris formula is a model which is widely accepted in fatigue analysis.The importance of Paris formula in fatigue life calculation was discussed by analyzing the fatigue fracture of 10.9-grade bolts for pressure vessel.Moreover,the accuracy of Paris formula in failure prediction was also verified.The chemical element analysis,metallographic structure analysis and electron microscopy obser-vation were conducted.The fatigue bands were measured and the data fitting of fatigue band width was performed for the inversion of the fatigue life of two bolt fracture.The results indicated that the crack propagation life of # 1 bolt and 2 # bolt were 17 251 cycles and 19 549 cycles,respectively.The finite ele-ment model verification results showed that the crack propagation life of # 1 bolt and 2# bolt were 16 228 cycles and 18 525 cycles,respectively,which were in good agreement with the proposed data.The relative error of fatigue life between the analogue simulation and calculation result were not more than 6％.It was indicated that Paris formula could be used for the accurate prediction of bolt failure under certain condi-tions,and it provided reliable reference for the improvement of structural part safety.
M16 boltfatigue fractureParis formulafatigue lifequantitative inversion of fracturefinite el-ement verification
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