SCLD板模态控制模型及振动控制

为有效抑制薄板在外界激励下的低频振动,对机敏约束层阻尼(SCLD)结构进行了主动振动控制研究.首先,考虑了黏弹性材料随温度与频率变化的阻尼特性,结合GHM阻尼模型建立了耦合系统有限元动力学分析模型;其次,考虑到结构动力学模型自由度庞大,采用物理坐标下自由度动力缩聚和状态方程下复模态截断进行了两次降阶,并通过复模态空间向实模态空间转换,得到了低维实模态控制模型;最后,通过模态实验验证了理论模型,并基于低阶控制模型设计了振动控制器,证明了研究方法的正确性.研究结果表明,采用本文的组合降阶方法可以有效地对SCLD结构进行降阶,对模态控制模型主动控制取得了良好控制效果:在单位阶跃激励下,振动响应衰减时间从0.20 s缩短为0.08 s;在随机白噪声激励作用下,振动响应均方根值降低了39.65%. 

Modal Control Model and Vibration Control of SCLD Plate

To effectively suppress the low frequency vibration of thin plate, the active vibration control of smart constrained layer damping (SCLD) structure was studied. Firstly, the damping characteristics of viscoelastic material varying with temperature and frequency were considered, and coupling finite element model for dynamics analysis was established based on GHM damping model. To address the large numbers of degrees of freedom of dynamics analysis model, model reduction was conducted through dynamic condensation in physical coordinate and complex modal truncation in state equation, and low-dimensional real modal control model was obtained from the conversion of complex modal space to the real modal space. Finally, the theoretical model was verified by modal experiment, and vibration controller was designed based on low-dimensional control model to validate the proposed method. The results show that the proposed combination reduction method is effective for SCLD structure. For the modal control model, the vibration control effect is desirable: the decay time of vibration response is shortened from 0.20 s to 0.08 s under unit step excitation, and the root mean square values of vibration response decreases 39.65% under gauss white noise excitation.