流体内压作用下封闭筒壳内力分析

Analysis of membrane forces within closed cylindrical shell subjected to internal hydraulic pressure

采用无矩理论,对承受流体内压的椭圆形截面封闭筒壳作了内力分析.通过分析内力沿纵向和周向的变化曲线,指出在两端简支条件下,纵向拉压力T11为主要内力,其最大值为平错力S最大值的7倍多;在截面的中和轴附近T11为压力,远离中和轴T11转变为拉力.平错力S沿周向的分布类似于正弦曲线,以截面中和轴为界改变S的符号,这种内力分布导致截面产生翘曲变形.周向内力T22无论沿纵向还是在周向都是拉力,其变化平缓,数值与T11和S相比甚微,不会成为设计中考虑的控制因素.

Using the membrane theory, the membrane forces of a horizontal cylindrical barrel with an elliptical crosssection which is subjected to internal hydraulic pressure are calculated and two sets of curves are plotted giving the forces variation along longitudinal and circumferential directions, respectively. The result shows that the longitudinal force T11 is dominant among the membrane forces, having a maximum of more than seven times as the maximum shear S, the force S in the circumferential direction varies with the coordinate α2 and changes its sign at the neutral axis of barrel's crosssection, causing the section perpendicular to the coordinate α1 to warp, the circumferential normal force T22 is the least important one due to its tiny value compared to T11 and S; it can never be the controlling factor in the shell design.