复合材料压力容器含凹陷内胆屈曲的有限元分析

Finite element analysis of the buckling of the liner of composite pressure vessel with depression

提出了一种复合材料压力容器含凹陷金属内胆屈曲的三维有限元分析方法。基于平面应变假设,建立了含凹陷半圆环收缩屈曲分析模型,通过修改有限元模型中内胆的节点坐标,将内胆初始凹陷引入模型中,采用非线性迭代法逐步增大面内载荷,实现了含凹陷半圆环的收缩屈曲分析。在此基础上,建立复合材料压力容器含凹陷内胆的三维有限元分析模型,同时考虑自紧工艺后内胆残余应力的环向分量与轴向分量,实现了复合材料压力容器自紧工艺后含凹陷内胆的屈曲分析。以130 L球形封头薄壁铝合金内胆全缠绕复合材料压力容器为例,分析了含凹陷内胆的临界屈曲载荷以及屈曲发生时内胆的应力及变形。结果显示,含初始缺陷的内胆在自紧工艺之后屈曲模式为局部屈曲;初始凹陷深度越大,临界屈曲载荷越低;与直筒段中部的距离为凹陷轴向宽度1/2的区域和直筒段靠近封头的金属内胆区域存在凹陷易发生屈曲,是金属内胆的薄弱环节。

A method for buckling analysis of liner of composite pressure vessel with depression was proposed.Based on the assumption of plane strain,the shrinkage buckling analysis model of the semicircular ring with depression was established,and the depression was introduced into the finite element analysis model by modifying the coordinates of nodes.The nonlinear iterative method was used to gradually increase the in-plane load,and the shrinkage buckling analysis of the semicircular ring with depression was analyzed.On this basis,a three-dimensional finite element analysis model of composite pressure vessel containing a liner with depression was established,the hoop and axial components of the residual stress of the liner after autofrettage was considered to analysis the buckling of the liner with depression after autofrettage of composite pressure vessel.Taking a 130 L spherical head and thin-walled aluminum alloy liner full-wound composite pressure vessel as an example,the critical buckling load of the liner and the stress and deformation of the liner when buckling occurred were analyzed.The results show that the buckling mode of the liner with initial depression after autofrettage is local buckling;the greater the initial depression depth,the lower the critical buckling load;the area where the distance from the middle of the straight section is 1/2 of the axial width of the depression and near the head of the straight section is prone to buckling,which is the weakness zone of the metal liner.