几何缺陷对复合材料加筋平板轴压屈曲影响研究

Study on Effect of Geometry Imperfection on Buckling of Compressive Load for Composite Stiffened Panel

当前的设计准则要求复合材料结构在限制载荷下蒙皮不发生局部屈曲,因此对蒙皮屈曲载荷的准确预测至关重要。设计了三种构型复合材料加筋平板轴压试验件,研究蒙皮在轴压载荷下的屈曲和后屈曲;采用线性特征值有限元方法计算了蒙皮的轴压屈曲载荷;采用多阶屈曲模态线性组合的方式引入初始缺陷,应用非线性方法计算了蒙皮轴压屈曲载荷并进行了缺陷灵敏度分析。计算结果和试验结果对比表明:当前计算蒙皮屈曲的工程方法过于保守,有限元方法可以更准确的计算蒙皮的屈曲载荷;初始缺陷对复合材料平板屈曲载荷有一定影响,其影响大小与缺陷幅值息息相关,不考虑该缺陷,会得到非保守的计算结果。

Local buckling of the thin skin of the fuselage stiffened panel below limit load is not allowed under current design criterion,then it is very important to accurately predict the buckling load of the thin skin.Three different composite stiffened panel configurations are designed to investigate the buckling process of the skin under compressive load;Modified engineering approach and linear eigenvalue analysis are employed to calculate the buckling load of the skin;a liner superposition of the buckling modes was used to impose out-of-plane geometric imperfection of the skin;the buckling load of the skin with geometry imperfection is calculated by using the nonlinear finite element method and the sensitivity analysis is also conducted.The comparison between the calculated results and the experimental proved that the nonlinear finite element analysis considering geometry imperfection can be used to predict the buckling load of the thin skin.