曲轴的建模及其自由模态分析

根据EQB140-20曲轴的原始几何尺寸，依据一定的简化条件，建立了曲轴的有限元网格化模型。并且利用有限元理论计算了曲轴的前五阶自由模态。结果表明，曲轴在低阶频率下，主要以弯曲模态为主。然后在曲轴的某个位置开设了不同深度的横向裂纹，研究了曲轴上存在裂纹以及裂纹的深度变化时，曲轴的固有特性的变化情况。结果表明，裂纹的存在，并不改变曲轴的自振形式，但是曲轴的固有频率与不合裂纹前相比，却有了明显降低，随着裂纹的不断加深，固有频率的降低也越来越大，固有频率的降低可以看作曲轴上存在裂纹的一个指标。

Modeling and Free Modal Analysis of the Crankshaft

According to the original geometry size of EQB 140-20 crankshaft, according to certain condition of simplifying, the finite element network has been used to set up the crankshaft formats models. The first five free modes of crankshaft that utilized finite element theories are calculated. The result indicates, crankshaft is under lower frequencies, rely mainly on crooked mode mainly. Then a certain location in crankshaft offers different crackles of degree of depths, the article studies crankshaft crackle and the degrees of depth of crackle when changing, the situation of change of crankshaft intrinsic characteristic. The result indicates, the existence of the crackle, the ones that do not change crankshaft are from the form of shaking, but the natural frequency of the crankshaft is reduced obviously with comparing before not including the crackle , With the constant intensification of the crackle, the reducing of natural frequency is bigger and bigger too. The reducing of natural frequency can be regarded as an index that the crackle exists as the crankshaft.