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建立一种悬停状态下无轴承复合材料旋翼气动弹性稳定性分析新模型。修正Bauchau大变形梁理论建立无轴承复合材料旋翼桨叶的非线性应变-位移关系,据复合材料特点推导桨叶本构关系并构造新的24自由度梁单元,将桨叶视为多路传力系统,应用Hamilton原理建立桨叶运动有限元方程,分析悬停状态下具有复合材料柔性梁无轴承旋翼气动弹性稳定性。数值计算结果表明:采用该模型的无轴承旋翼气动弹性稳定性计算结果与试验数据吻合程度较传统中等变形梁理论更好;具有负变距-摆振耦合的复合材料柔性梁结构可提高无轴承旋翼气动弹性稳定性及正变距-摆振耦合结构降低旋翼气动弹性稳定性;负铺层角较大小相同正铺层角旋翼气动弹性稳定性更好;铺层厚度减少有利于增加旋翼气动弹性稳定性。
A New Model for Aerodynamic and Elastic Stability Analysis of Bearingless Composite Rotor under Hovering Conditions. The nonlinear strain-displacement relationship of rotor blades of bearingless composite materials is modified by Bauchau large deformation beam theory. Based on the characteristics of composite materials, the constitutive relation of blades is deduced and a new beam unit of 24 degrees of freedom is constructed. The blades are considered as multi-pass transmission systems , The finite element equation of blade motion is established by using the Hamilton principle and the aerodynamic stability of a bearing-free rotor with composite material under hovering condition is analyzed. The numerical results show that the calculated results of the aeroelastic stability of the bearingless rotor with this model are more consistent with the experimental data than those of the traditional medium deformation beam theory. The composite flexible beam with negative pitch-vibration coupling can improve the bearinglessness The aeroelastic stability of rotors and the positive variable pitch-wobble coupling structure reduce the aeroelastic stability of rotors; the same is true for the negative ply angles; the aerodynamic stability of the rotors is better; and the decrease of ply thickness is conducive to increasing aeroelasticity stability.