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为计算变截面层合管杆件整体稳定承载力,提出一种基于能量法的理论计算模型。采用基于三维梁理论的层合管等效抗弯刚度计算方法,计算了等截面段、变截面段的等效工程弹性系数。在考虑剪切变形的影响以及杆件变截面对轴压挠曲线函数影响的基础上,基于能量法推导了变截面杆整体稳定承载力解析公式。以NASA复合材料变截面杆为算例,进行了理论计算和有限元数值模拟,结果显示:同时考虑上述两因素的理论计算结果与有限元结果最为接近,剪切变形对临界承载力的修正可达10%以上,轴压挠曲线函数的变化对承载力的修正约为1%,可忽略。以锥长和锥角为参数,对变截面杆的承载力、体积和承载效率进行双参数分析,发现变截面对弯曲变形能的影响远大于对剪切变形性能的影响,采用变截面形式能够提高层合管承载效率,且一定锥长下存在承载效率最高对应的最优锥角。
In order to calculate the overall stability of variable cross-section pipe members, a theoretical calculation model based on energy method is proposed. Based on the calculation method of the equivalent bending stiffness of the laminated pipe based on the three-dimensional beam theory, the equivalent engineering elastic coefficient of the equivalent section and the variable section is calculated. Based on the influence of shear deformation and the influence of the variable cross section of the rod on the curve function of the axial flexure, the analytic formula of the overall bearing capacity of the variable section rod is derived based on the energy method. Taking NASA composite cross-section bar as an example, the theoretical calculation and finite element numerical simulation are carried out. The results show that the theoretical calculation results of the above two factors are most similar to the finite element results, and the correction of the critical bearing capacity Up to 10%, the change of axial compression curve function is about 1% correction of bearing capacity, negligible. Taking the cone length and taper angle as parameters, the bearing capacity, volume and load-bearing efficiency of the cross-section bar were analyzed by two-parameter method. It was found that the influence of the variable section on the bending deformation energy was far greater than that on the shear deformation performance. Improve the bearing capacity of the laminated pipe, and the optimal cone angle corresponding to the highest bearing efficiency exists under a certain cone length.