简化有限元方法的波纹管模态分析

采用简化方法对单层U型波纹管进行有限元模态分析。在长度,质量,对轴线转动惯量,体积,轴向弹簧比率以及周向弹簧比率不变的前提下,把波纹管简化成直壁薄管,用直壁薄管模型代替波纹管模型进行有限元模态计算。简化了计算模型,减少了计算量,提高了计算效率。本文给出了明确的等效直壁薄管的几何参数,物性参数的求解公式,改变了Broman人为设定直壁薄管厚度的方法,取得了更加准确的计算结果,使利用直壁薄管模型求解波纹管固有频率具有通用意义。进行了直壁薄管模型得到模态振型与波纹管模型得到模态振型之间的比较,认为直壁薄管模型可以求解波纹管的振型。

Modal Analysis of Bellows with Simplified FEM

A simplified method is adopted to analyze U-bellow modal, which is assumed as an equivalent thin-walled pipe with the constant mass, length, rotary inertia, volume, axial spring rate and torsion spring rate. The beam element is used for thin-walled pipe model in FEA instead of shell elements for bellow model and the model size is largely reduced. The equation for the inner radius and the thickness of thin-walled pipe is developed according to the constants of rotary inertia and volume. Comparing with the Broman's assuming of the thickness, the more exact result of natural frequencies is achieved. The simulated resuts demonstrate comparatively that the mode shape by beam element coincides with one by shell element well.