磁橡胶约束阻尼壳的宽频振动控制能力研究

Vibration Control for Cylindrical Shell with Magnetic Rubber Layer Damping Treatment within a Broad Frequency Range

不同于传统被动约束阻尼处理（PCLD），磁橡胶约束阻尼处理（MRLD）采用磁化的铁一橡胶混合粉末替代PCLD的粘弹性材料，不是通过粘结而是磁力吸附在钢制振动体上，在振动时交界面处发生滑移使部分能量转化为热能，从而降低振动。采用假设模态法计算PCLD的频率响应，再基于周期耗能相等原理，将MRLD与PCLD等价，得到MRLD壳的模态损耗因子，研究了MRLD处理对简支壳阻尼的影响。分析结果表明：对于1000～3365Hz间前11阶模态频率的MRLD壳振动，当激振力低于16～20倍的起滑激励力F0时，MRLD均可获得比PCLD更好的阻尼；但各模态的F0的差异仅在3～4倍内；因此在前11阶模态频率范围内，激振力可以存在一个交集，在此交集内可同时引起各阶模态的阻尼层发生滑移，从而能控制壳的宽频振动。

Different from the conventional passive constrained layer damping treatment(PCLD),magnetic rubber layer damping treatment(MRLD) chooses the rubber layer,a mixture of ferrite-magnitizing powder,to replace viscoelastic material of PCLD.Magnetic rubber layer is easily attached to a vibrating steel body by the magnetically attractive force not by adhering.While vibrating,a sliding friction is generated on the interface between rubber layer and steel body and converts a portion of vibrating energy to thermal energy to reduce vibration.With assumed-mode method,the frequency responses of a PCLD cylindrical shell are first calculated.The modal loss factors η of the MRLD shell are then obtained based on the derived equation of the PCLD shell via equating the dissipation energy by MRLD to that by PCLD in a vibrating cycle.The damping effects of MRLD on a simply-supported cylindrical shell are investigated.The results reveal that for the first 11 modal frequencies ranging from 1000 Hz to 3365 Hz,when the excitation force F does not exceed the value of about 16 to 20 times F 0,the starting slide excitation force,MRLD has superior damping ability to PCLD,but F 0 is only about 3 to 4 times difference among these frequencies,therefore there exists a common range of excitation force F,within which slide can be generated and the damping improvement of the MRLD shell versus PCLD shell can be achieved simultaneously for a broad frequency range.