几何参数对复合材料圆柱壳折减因子的影响

Influence of geometric parameters on knock-down factor of composite cylindrical shells

对于弹箭体结构中常见的复合材料圆柱壳结构,在计算其轴压屈曲载荷时需要对理论线性解进行折减,从而弥补实际含缺陷产品与理想的完美结构之间的差别。目前,虽然可以基于非线性有限元分析得到较为精确的折减因子数值,但是折减因子随结构几何参数变化而变化的具体规律尚未厘清。针对这一问题,研究当复合材料圆柱壳的长度、半径、单层厚度等几何参数的变化对折减因子的影响,发现无论铺层方式如何,折减因子总是与半径和单层厚度呈近似线性的正相关,而与结构长度间呈近似线性的负相关。在初始设计阶段应用这一结论,可以减少非线性有限元分析的次数,提高设计效率。

Composite cylindrical shells are commonly used in missile and rocket structures.When calculating the axial compression buckling load,the analytical linear solution needs to be knocked down to compensate for the difference between the actual as-built product and the ideal perfect structure.Although the knock down factors can be obtained from nonlinear finite element analysis,the regularity of the knock down factors varying with the structural geometric parameters has not been clarified.To this issue,the influence of the geometric parameters,such as length,radius,and monolayer thickness,on the knock down factors was investigated.It is showed that the knock-down factors are always approximately linear,positively correlated with the radius and monolayer thickness,and approximately linear negatively correlated with the structural height,regardless of the stacking sequence.By applying these conclusions into the primary design phase,the numbers of finite element analysis can be reduced hence the design efficiency can be improved.