采用等效刚度有限元模型的复合材料机翼颤振分析

Flutter prediction of composite wing using finite element method with equivalent stiffness

采用等效刚度方法,研究了一种适用于复合材料机翼初步设计阶段的动力学和颤振分析的简化结构有限元模型。该方法首先计算不同布局形式的加筋壁板的刚度矩阵,然后将其赋予与加筋壁板平面形状相同的光板(等效板)上,使加筋壁板和等效板具相同的力学性能。以某客机概念方案的机翼为例,建立了反映实际结构详细有限元及其等效刚度有限元模型。通过编程实现了自动化生成等效模型,极大地减少了建模和分析时间。计算结果和对比分析表明,两种模型的固有频率、振动模态和颤振分析结果吻合得很好,从而验证了等效刚度方法在机翼结构动力学和颤振分析方面的准确性。

A method using the concept of equivalent stiffness was developed for the modal and flutter analysis of composite wing in preliminary design. The stiffness matrices calculated from different stringer-stiffened panels were applied to FEM shell properties of the same planform panels （i. e. , unstiffened panels） that have the same mechanical properties as those of the original stringer-stiffened panels. The advantage of this method is that the complicated definition of composite material and modeling of stiffeners are avoided in the equivalent finite element model （EFEM） and the complicacy of finite element model is reduced, while the feature of structural layout of wing was still retained. A wing of the notional civil jet was used as an example to verify the method. Both the detailed finite element model （DFEM） and the EFEM of wings are created and analyzed for flutter predic tion. Especially, the EFEM is automatically created by running scripts, and lots of time is saved from the process of modeling and analysis. The results indicate that the natural frequencies, mode shapes and flutter speed from the two models are in a very good agreement. The accuracy of the EFEM for the modal and flutter analysis of wings is verified. The EFEM provides an attractive method for wing flutter prediction in aircraft preliminary design phase due to its rapid modeling and satisfactory accuracy.