| Continuous variable thickness structure is a new structure developed in recentyears. Research shows that, different structure will have different effects in fatigueperformance. At present, study on fatigue performance of variable thickness blanks islacked. This paper focuses on fatigue performance of variable thickness blanks, themain contents are followed:Design a variable thickness specimen, and based on the quality to determine thethickness of equal thickness specimen. The small sample mean S-N test was used inthis paper to obtain high-cycle fatigue life: the fatigue strength test and fatigue test offinite life need parameters from material tensile test, so the material test is done toobtain the material yield strength, tensile strength, elastic modulus and so on; the upand down method is conducted under the stress ratio R=0.1, the fatigue strength limitsfor the two samples are calculated from the test result. The6level stress is used in thetest for the finite life under stress ratio R=0.1. The whole fatigue data for the twosamples is collected and fitted to achieve the total S-N curve.The lower bound S-Ncurve ensure test data have a probility of90%fall above the lower bound curve. It isreliable, so it is used as the main reference in the fatigue analysis. According to thecorrelation analysis can be found that under the same force amplitude, the variablethickness sample endure more cycles before failured.Finally, fatigue simulation is done in two specimens using Patran2010andMsc.fatigue software to obtain fatigue life distribution of two samples undertwo stress state. The reliability of the model is verified, and optimized the variablethickness structure based on equal quality, the life of the structure is improved afteroptimization. |
