内结合圆角处含有裂纹的曲轴动力学模型

Modeling on the Dynamics of Crankshaft with Crack in Fillet Region

建立裂纹曲轴的动力学模型,对裂纹曲轴的非线性动力学进行仿真与分析.针对内结合圆角处出现常见裂纹的曲轴,采用Timoshenko梁单元与裂纹梁单元相结合的方法建立其有限元模型;根据裂纹曲轴运动的特点及工作过程中裂纹开闭的实际情况,提出在旋转坐标系下建立其非线性振动模型.以一四缸发动机的曲轴为例,对含不同深度裂纹曲轴的振动响应进行了仿真计算,对其扭振、纵振及弯曲振动的频谱特性进行分析,提取并总结了裂纹曲轴动力学的一些特征.研究表明,所提出的裂纹曲轴动力学模型简洁且容易实现,裂纹曲轴的动力学特性分析为曲轴裂纹故障诊断奠定了理论基础.

A model for modeling and analyzing the dynamics of cracked crankshaft was developed, and the nonlinear vibrations of the cracked crankshaft were simulated and analyzed. A crankshaft with a frequent crack in crankpin-web fillet region was investigated, and a finite element model based on combination of Timoshenko beam element and cracked bean element was proposed. The breathing behavior of the crack and the motion characteristic of crankshaft under operating condition were studied, and a model of nonlinear motion was established in a rotating coordinate system. A crankshaft of four in-line cylinder engine was applied as an example, and the vibration response of crankshafts with different depth crack was simulated. The study indicates that the model proposed for cracked crankshaft is compact and effective; the analysis on dynamics of cracked crankshaft lays a theoretical foundation for the diagnosis on crack fault of crankshaft.