磁约束阻尼悬臂壳的轴对称振动分析

AXISYMMETRICAL VIBRATION ANALYSIS OF A CANTILEVER SHELL WITH MAGNETIC CONSTRAINED DAMPING LAYER TREATMENT

提出了一种新型有效的方法来降低悬臂壳的轴对称振动.该方法的原理是在约束层端部上及固定端分别设置引力排列的永磁体,振动时磁体间的动态磁力可使阻尼层获得比传统约束阻尼处理方法更高的剪应变,阻尼层耗能增加,从而降低结构的共振峰.从夹层单元微元体受力分析出发,建立了局部磁约束悬臂壳的轴对称振动分析模型,得到分别用约束层纵向位移u30、积分常数c和径向位移w表示的夹层壳体单元的纵向和周向力平衡方程.在此模型中,考虑了振动时因u30引起动态磁力的变化,使得此模型能描述MCLD结构的动态及阻尼性能.此外,通过比较MCLD处理与传统的约束阻尼处理对磁约束悬臂壳的轴对称振动的控制效果,分析表明:磁约束处理可同时控制悬臂壳前几阶模态的振动.

A new surface treatment was proposed to attenuate the undesirable axial symmetrical vibrations of a cantilever cylindrical shell. The proposed treatment relies on, in its operation, the use of the attraction arrangement magnets in the clamped end and on the constraining layers root . The interaction between the magnets and the visco-elastic layers aims at enhancing the energy dissipation characteristics of the damping treatment. This new treatment will be called Magnetic Constrained Layer Damping (MCLD) treatment. The analytical model of the axial symmetrical vibration of the cantilever cylindrical shell treated with fully MCLD has been derived. The longitudinal and circumferential force equilibrium equations in terms of the axial displacement u_30 in constraining layer and radial displacement w and the constant c were derived. Since the dynamic magnetic force resulting from the variation of u_30 can be incorporated into the boundary conditions, the developed model can describe the dynamics and the damping characteristics of the structure with MCLD .Also the performance characteristics of the MCLD was compared with the corresponding performance of the conventional Passive Constrained Layer Damping (PCLD). The obtained results indicate that using the fully MCLD treatment can simultaneously suppress vibration for the first several modes of the cantilever cylindrical shell.