谐振式曲轴弯曲疲劳试验恒载荷控制方法

为研究谐振式曲轴弯曲疲劳试验中试件裂纹扩展对谐振系统载荷放大特性的影响，且在此基础上实现试验系统的高精度恒载荷控制，对谐振系统的振动模型进行了详细的模态和谐响应有限元分析，通过对计算阻尼系数合理修正，有限元分析的结果可以很好地符合试验结果。根据多种裂纹尺寸条件下的分析结果，建立了试件裂纹尺寸、试件承载水平与系统振动特性之间的关系。讨论了为实现恒载荷特性，在试验过程中对加载频率进行调整的必要性，提供了以振动加速度为参考状态变量进行恒载荷控制的依据。

Investigation of Constant-load Control Method for Resonant Crankshaft Fatigue Test

In order to study the influence of testee's crack growth on load-amplification character of crankshaft resonant fatigue test machine, and find out the way to achieve constant-load control, CAE model was constructed and detailed FEA for modal and harmonic were conducted. By modifying damping factor of the analysis model, FEA result could well agree with test data. More FEA results showed that as the crack growing, the load-amplification character would change significantly, which meant that it was necessary to regulate the loading frequency to meet constant-load control request. With furthermore calculation, the dynamic relationship between the bend moment on crankshaft and the test machine resonance characteristic at different crack size was set up. This relationship is to be as the reliance on which the loading moment on crankshaft can be controlled in scheduled range in the fatigue test.