Mechanical Study On Fatigue And Damage Of Piston

This work employs the theory of fracture mechanics, combines the experiment, on the basis of numerical simulation, have launched research to the fatigue reliability and safety problem of silicon aluminium alloy piston.1. The mechanical fatigue experiment. Utilizing piston of machinery fatigue testing machine, this work executes fatigue test. The result indicates that the great tensile stress generates at the upper end of the piston pin seat.2. The finite element analysis of piston. This work calculates piston's thermal stress field, mechanical stress field and coupling stress field. The calculation results indicate that the great tensile stress generates at the upper end of the piston pin seat. Via analyzing the dynamics under the transient loading, the circulatory stress of the crack tip is computed, and the critical crack length is calculated.3. The expression of the piston shape geometry factor. Using the sub-structure model method, this work exerts the crack body to compute the stress intensity factor for different crack depths. The calculation results are extremely tallied with the academic values offered by the handbook; the limiting error is less than 6%. Thereby the expression of the shape geometry factor is obtained by curve fitting.4. Based on the theory of rupture, the crack is considered to be type I, and the crack location and expansion direction also have been confirmed. The special crack is separated into two sections, one is the horny crack at the aperture and the other is the surface crack at the lumen. In order to calculate the exact data, a modificatory Paris formula is available to prognosticate the fatigue life-span of the piston.