基于混合硬化模型的超高压泵头体自增强研究

The autofrettage analysis of the ultra-high pressure pump head body requires an accurate description of the hardening behavior and Bauschinger effect of the material. Based on the derivation of the mixed hardening elastoplastic constitutive relationship, the developed subroutine UMAT is applied to the hydraulic autofrettage elastoplastic finite element analysis of a certain type of ultra-high pressure pump head body. A method for judging whether the autofrettage residual stress causes reverse yielding by the change of the nodal plastic strain increment is proposed. By analyzing the relationship between the autofrettage pressure and the maximum equivalent stress when the autofrettage pump head body is working, the optimal autofrettage pressure of this type of pump head body is obtained. The determination of the optimal autofrettage pressure of the pump head body should be based on the premise that the autofrettage residual stress does not cause reverse yielding and on the principle that the peak value of the equivalent stress is the smallest under the action of the maximum working internal pressure. The research results show that under the action of the working pressure, the maximum equivalent stress in the inner cavity of the pump head body treated with the optimal autofrettage pressure decreases significantly, and the stress distribution is more uniform.

超高压泵头体自增强分析需要准确描述材料的硬化行为和包辛格效应。在推导出混合硬化弹塑性本构关系的基础上，将开发的子程序 UMAT 应用于某型超高压泵头体的液压自增强弹塑性有限元分析中。提出了以节点塑性应变增量的变化情况来判断自增强残余应力是否导致反向屈服的方法。通过分析自增强压力与自增强泵头体工作时最大等效应力的关系，得出该型泵头体的最佳自增强压力。泵头体最佳自增强压力的确定应以自增强残余应力不发生反向屈服为前提，以最大工作内压作用下等效应力峰值最小为原则。研究结果表明，经过最佳自增强压力处理的泵头体在工作压力作用下，内腔最大等效应力明显下降，应力分布更加均匀。...