半球壳准静态压缩下的变形行为研究

Deformation Mode of Hemispherical Shell under Static Load

采用顶点及平板下压加载的加载方式对半球壳的准静态压缩进行了实验研究,获得了半球壳的变形模态及力-位移曲线。通过准静态压缩实验观察在不同加载方式下球壳变形模式随压缩深度的变化,发现半球壳出现了轴对称和非轴对称变形形式。利用ABAQUS有限元软件对球壳准静态压缩过程进行数值模拟,分析加载方式与球壳尺寸等对变形行为的影响。结果表明:球壳在压缩下的变形可分为加载点附近局部压平、轴对称凹陷以及形成非对称多边形3个阶段。其中,在压平向凹陷转变时,小截面平头加载的接触力-位移曲线产生了突跳现象,但在半球头与平板加载时未出现,且凹陷之后,半球头加载下接触力的增加速率减小,而平板加载下接触力的增加速率几乎保持不变。壳的径厚比越大,后期的变形程度越复杂;径厚比越小,由压平到凹陷转变时的临界荷载越大,球壳承载力越大。计算表明,在本研究范围内球壳凹陷前后接触力的大小以及增加速率只与厚度有关,而与半径的相关性则较小。

Axial compression on stainless steel spherical shells was performed under different loading styles by quasi-static tests, and the deformation energy of spherical shell was calculated. The stress distribution was observed through the photo elastic experiment so as to analyze the deformation model of hemispherical shell under static load. It can be seen that,the maximum stress occur near the loading point at the beginning, and extends outward in a circular form with the compression depth increases, e- ventually larger stresses distribute near polygon vertex, loading point and the region between them. It＇s also simulated by ABAQUS software to analysis the influence of loading method and hemispher- ical shell size on deformation mode. The result shows：The ability to resist deformation of spherical shell decreases along with the R/t increase;under flat nosed compression,the contact force of spherical shell decreases after reaching the peak,but it doesn＇t under other loadings;the increasing ratio of con- tact force is only related with thickness, but not with radius.