轴向覆盖磁约束阻尼条对悬臂壳非轴对称振动的影响

EFFECT OF AXIAL-COVERED MAGNETIC CONSTRAINED DAMPING STRIPS ON UNAXIAL-SYMMETRICAL VIBRATION OF A CANTILEVER CYLINDRICAL SHELL

应用Rayleigh-Ritz方法建立了局部磁约束阻尼壳的振动分析模型.选取约束层的横向振动模态和面内振动模态作假设模态,形成横向位移和面内位移.调查了不同约束阻尼层配置下,轴向覆盖磁约束阻尼条对悬臂壳非轴对称振动模态(m=1,n=1)损耗因子的影响.研究表明:当阻尼层远离该模态的节线(θ=±π/2),磁约束阻尼处理的阻尼改进效果越明显.阻尼层设置在θ=0,π处,该模态的损耗因子最大,MCLD处理的阻尼改进效果也最显著,损耗因子提高约40%.可以通过改变阻尼层的长度及宽度可增加损耗因子,但随二者的增加,磁约束处理对阻尼的改进作用减小.

The Rayleigh-Ritz method was applied for the damping analysis of flexural vibration of the cantilever cylindrical shell with partial magnetic constrained layer damping treatment （MCLD）. The analysis was carried out in terms of resonant frequencies and the associated modal system loss factors. Single-term solutions for respec- tive modes were assumed for the x-axial and circumference directions in-plane displacements of the constraining layer and the radial displacement of the shell . We obtained the improvement of damping characteristics for the unaxial-symmetrical vibration mode （ m = 1, n = 1 ） using MCLD patches with different configurations. The obtained results indicated that the MCLD with patch far from the line θ = ＋ π/2 could enhance significantly the loss factors η. Provided that the damping layer is located at θ = 0,π, both PCLD and MCLD can gain maximal modal loss factor, and MCLD can increase the loss factor about 40 per cents verus PCLD. Increasing damping layer length or circumference angle can cause r/rise, but decrease the damping improvement effect of MCLD.