复合材料圆管阻尼特性研究

本文采用复模量方法的Timoshenko梁理论和模态应变能法的Love一阶壳理论建立了复合材料圆柱壳动力学方程，进行了相应的模态测试，并与有限元及试验结果进行对比。本文计算结果与有限元及试验结果符合良好。根据所建立的动力学方程，分析了梁理论的局限性，研究了铺层角度、长径比、厚径比、边界条件及环向波数对复合材料圆管阻尼特性的影响。结果表明：壳理论模型能对复合材料圆管的弯振阻尼特性进行准确分析，梁理论模型仅在轴向振动损耗占优的情况下比较准确；一弯模态损耗因子随长径比的增大而减小，在大于10时趋于定值；厚径比对一弯模态损耗因子影响较小；一弯模态损耗因子随铺层角度的增大先减小再增大后轻微减小，在铺层角度<30°和>75°时，双边固支边界的一弯模态损耗因子最大，在30°~75°之间时，悬臂边界的最大。

Damping Analysis of Composite Cylindrical Tube

Two theoretical ways were used to obtain the modal damping of composite cylindrical tubes in this paper. The Timoshenko beam theory was applied by implementing complex modulus method and the modal strain energy method was used in Love’s first order shell theory. A hammer test was applied to obtain modal frequency and damping results of composite cylindrical tubes. By comparing with finite element method and test results, theoretical models show a good agreement. According to the kinetics equation established, the limitation of beam theory was analyzed. Influences of laminated angle, aspect ratio, thickness diameter ratio, boundary condition and circumferential number on damping of composite cylindrical tube were studied. The results show that the shell theory model can afford an accurate analysis of bend modes while the beam theory model only works when the axial vibration dissipation possesses the advantage. The 1st bend modal loss factor decreases with the increase of aspect ratio and tends to be the same when the aspect ratio is greater than 10. The 1st bend modal loss factor changes a little with the increase of thickness diameter ratio. The 1st bend modal loss factor decreases firstly, then increases and decreases a little with the increase of laminated angle. When the laminated anlge is less than 30° and bigger than 75°, the 1st bend modal loss factor reaches the maximum for clamped-clamped boundary, and it reaches the maximum between 30° and 75° for cantilevered boundary.