As fillet rolling hardening technique has been widely used to enhance the bending fatigue strength of cast iron crankshaft, the residual stress due to fillet rolling must be considered in fatigue analysis. For a fillet-rolled cast iron crankshaft, a three dimensional roller-multidiameter shaft contact finite element model was established, and both bodies were flexible. The roller were used to simulate the rolling process by pressing in the roller, applying a relative revolution and unloading, and then the residual stresses induced by fillet rolling were obtained. After that, the bending stresses and strains near fillet by the action of bending moment in the fatigue test were computed by a finite element static analysis of the crankshaft section. In order to describe the properties of cast iron, the material model that has the different behaviors in tension and compression were used the rolling and bending calculation. The monotonic tension and compression stress-strain curves were chosen in rolling analysis, but the cyclic curves were used in bending computation. Finally the life of critical position near fillet region was got by the local stress/strain fatigue analysis method, in which the amplitude of strain was used as a basic parameter and the residual stress caused by fillet rolling was treated as a mean stress. The results agree with the bending fatigue test results of crankshaft sections well.%铸铁曲轴广泛采用了圆角滚压强化技术来提高其弯曲疲劳强度,进行疲劳分析时必须考虑滚压引入的残余应力.针对某圆角滚压铸铁曲轴,首先建立了与其对应的滚轮—阶梯轴三维柔—柔接触有限元模型,通过滚轮压入—相对转动—滚轮卸载模拟滚压过程,得到了圆角滚压残余应力；然后进行了试验弯矩作用下的曲轴单拐有限元受力分析得到了圆角的弯曲应力及应变.为了模拟铸铁材料的特性,滚压及弯曲计算均采用了拉压异性的材料模型,但前者选用单调拉、压应力应变曲线,而后者选用循环拉、压应力应变曲线.最后以疲劳试验弯矩作用下弯曲应变幅为基本参数,将滚压残余应力视为平均应力,利用材料应变—寿命曲线进行局部应力应变法疲劳分析,得到了曲轴圆角危险位置的寿命,与试验结果相符.
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