一种复合材料旋翼桨叶结构大变形分析方法的改进及验证

An improved method and its validation for large deflection analysis of initially twisted composite rotor blades

提出了一种适用于直升机旋翼复合材料桨叶大变形分析的改进方法。将旋翼桨叶变形分析分解为一维非线性分析和二维剖面特性分析,并考虑横向剪切、翘曲对剖面刚度及弹性耦合的影响;为使方法适用于旋翼气动弹性分析,将应变能中的广义应变用参考轴线处的弹性运动表示,保留所有非线性项,推导出计算复合材料桨叶大变形的公式;采用有限元法处理方程,对梁结构进行了分析,并将大变形状态下的位移计算结果与Princeton梁实验值、Minguet复合材料梁实验值以及中等变形梁理论计算结果进行了比较,验证了大变形状态下本文计算方法的正确性;此外与中等变形梁模型计算结果的对比,验证了本文方法在计算精度上的提高。

An improved method is presented for large deflection analysis of the initially twisted composite rotor blades. Transverse shearing deformations, warping effects and elastic couplings are considered in the rotor blade cross section properties. The three-dimensional strain field in the rotor blade is expressed in the term of one-dimensional generalized strains. Based on the two-dimensional cross-section analysis and one-dimensional nonlinear beam analysis, the strain energy in the composite rotor blade is deduced. The generalized strains are expressed by the variables which describe the elastic motion of a reference line along the axis of the rotor blade, and all the nonlinear terms are included in the formulation. Analysis results based on a finite element discretization of the resulting equations are presented. Correlations between the analysis results and the experimental data from Princeton beam test and Minguet's composite beam experiments show that this method is valid for large deflection analysis of composite rotor blades. Compared with other analysis results based on moderate deflection beam theory, improvements of present method are obvious.