切割对磁约束阻尼处理固支板的振动特性的影响

EFFECT OF CUTOUT ON DAMPING OF A CLAMPED-CLAMPED PLATE WITH MAGNETIC CONSTRAINED DAMPING TREATMENT

在约束层根部设置引力排列的磁体,阻尼层的剪应变将大于传统约束阻尼处理(passive constrained layer damping treatment,PCLD)的剪应变,因此,采用磁约束阻尼处理(magnetic constrained layer damping treatment,MCLD)可使系统的阻尼得到显著地改善。文中应用假设模态法研究工程中常见的两边固支约束阻尼板的磁约束处理减振效果,推导出由板的横向模态坐标表示的特征方程。通过考察固支板的第一阶扭转模态(m=1,n=1)的损耗因子,研究将阻尼层等分切割为总的尺寸不变的两块阻尼层的阻尼变化情况。分析表明,在覆盖面积相同时,将阻尼块沿x方向等分为2块,将每块放置在板的宽度方向的边部,并沿模态节线y=W/2对称,可使MCLD获得更好的阻尼改进效果。

The shear strains of viscoelastic damping layers resulting from the attraction arrangement magnets on the constraining layers mot are higher than those of the conventional passive constrained layer damping treatment （PCLD）. Therefore, significant improvement of damping characteristics can be achieved by using the magnetic constrained layer damping treatment （MCLD）. A rectangular plate with clamped-clamped end boundary is also often applied in engineering. The damping preperty of magnetic constrained layer damping （MCLD） plate with above boundary was discussed. Assumed-mode method was applied for the damping analysis of flexural vibration of the clamped-clamped plate. A standard eigenvalue equations in terms of plate transverse modal coordinates were derived. Patches cutout effect with one or two segments of the same total size are then evaluated in terms of modal loss factors for the first torsional mode （m= 1, n=1）. Given the same area, when a patch is cut into two segments and set each segment at the edge of plate in the width direction and symmetrically along the modal nodal line y = W/2, using MCLD treatment can produce better damping than PCLD treatment.