螺旋缠绕复合材料圆柱壳屈曲特性

Buckling behaviour of helically wound composite cylindrical shells

为开展螺旋缠绕复合材料圆柱壳屈曲特性试验与数值研究,首先制作3个长径比(L/R)1.9~3.9的螺旋缠绕复合材料圆柱壳,试验研究其静水压力下失效模式。理论模型、有限元模型和试验结果具有良好的一致性。根据NASA SP-8 007规范、Shen理论及数值模型,分析讨论不同长径比对复合材料圆柱壳屈曲载荷的影响规律。结果表明:NASA规范与Shen理论值与试验载荷比值均小于1,采用层合板理论模型预测结果相对保守;当L/R<2.9时,采用线性屈曲分析预测结果相比考虑材料渐进损伤的弧长法较为接近实验值,最大误差为8.7%;当L/R>2.9时,宜采用非线性弧长法模型预测更为保守,其误差为0.8%,圆柱壳破坏直接由失稳引起,未达到强度极限。

The current study was an experimental,and numerical investigation of the buckling of helically wound com-posite cylinders.Composite cylinders of three lengths(L/R=1.9-3.9)were manufactured.Externally hydrostatic tests are con-ducted to determine the collapse modes of the three cylinders.The theoretical,experimental and numerical data agree well with each other.Subsequently,buckling loads calculated using finite element analysis results and empirical method results according to NASA SP-8007 and Shen's formulae,were compared with test results.Effect of the length to diameter ratio on buckling behaviour of composite cylindrical shells was investigated.The results show that the ratio of theoretical value cal-culated by NASA SP-8700 and Shen's formulae to test loads is less than 1.The prediction results of laminated plate theory model are relatively conservative.When L/R<2.9,the predicted results of linear buckling analysis are closer to the test val-ues than the arc length method considering progressive damage of materials,and the maximum difference is 8.7%.When L/R>2.9,the nonlinear arc length method is more conservative,with a difference of 0.8%.The failure of the cylindrical shell is directly caused by instability and does not reach the strength limit.