囊式蓄能器橡胶球囊屈曲失稳变形研究

Research on Buckling Instability Deformation of Rubber Balloon of Bladder Accumulator

囊式蓄能器工作时以压缩橡胶球囊内部气体的形式储存能量和稳定压力变化。基于理想气体状态方程和Mooney-Rivlin超弹本构方程,采用线性摄动和显式动力分析方法对囊式蓄能器流体腔有限元模型依次进行了特征值屈曲分析和非线性后屈曲分析。结果发现:在均布液压载荷作用下,橡胶球囊出现了3个凹坑的变形形态,与实验中出现的变形一致,表明产生3个凹坑变形原因是橡胶球囊发生了屈曲失稳;显式动力分析方法解决了橡胶大变形存在的计算收敛差、计算效率低等问题,为橡胶材料三维实体模型大变形模拟提供了一个良好的仿真方法;橡胶球囊流体腔模型腔体体积与腔内压力呈近似反比例关系,与理想气体绝热方程吻合,表明采用流体腔模拟橡胶球囊内部气体腔具有可靠性。

The bladder accumulator stores energy and stabilizes pressure changes in the form of compressing gas inside the rubber balloon during operation.Based on the ideal gas state equation and Mooney-Rivlin hyperelastic constitutive equation,the eigenvalue buckling analysis and the nonlinear post-buckling analysis of the finite element model of the fluid cavity of the bladder accumulator were carried out by linear perturbation and dynamic explicit simulation method.The results show:under the action of a uniform hydraulic load,the rubber balloon shows three pits deformed,which is consistent with the deformation in the experiment,indicating that the reason for the deformation of the three pits is buckling instability of the rubber balloon;the dynamic explicit simulation method solves the problems of poor calculation convergence and low calculation efficiency in the large deformation of rubber,and provides a good simulation method for the large deformation simulation of the three-dimensional solid model of rubber materials;the volume of the fluid cavity model of the rubber balloon is approximately inversely proportional to the pressure in the cavity,which is consistent with the ideal gas adiabatic equation,indicating that the use of fluid cavity to simulate the internal gas cavity of the rubber balloon is reliable.