聚氨酯–橡胶复合阻尼材料减振优化设计

Optimization Design for Vibration Reduction of Polyurethane–Rubber Composite Damping Material

隔离自由阻尼是在传统的自由阻尼结构上建立的一种减振处理方法。以隔离自由阻尼理论为基础,提出以硬质聚氨酯泡沫作为隔离层、橡胶为阻尼层制备用于抑制结构振动的聚氨酯–橡胶隔离复合阻尼材料。利用模态叠加原理和Lagrange方程,在考虑阻尼层剪切变形的基础上,推导出隔离自由阻尼悬臂梁的控制方程。在钢板悬臂梁上敷设隔离层与阻尼层厚度比值为1~3以及具有分段式隔离层的聚氨酯–橡胶复合阻尼材料,并通过单点锤击实验从幅频曲线、复合损耗因子、模态频率等方面对悬臂梁模型的减振性能进行对比分析。结果表明:隔离层与阻尼层的厚度比值由1增加至3时,模型的振动响应峰值降低了13%~62%,同时损耗因子明显升高;当厚度比超过1.5时,材料对模型低阶模态的减振效果持续提高,而高阶模态的减振效果趋于稳定;分段式隔离层的设计降低了隔离层的抗弯刚度,扩大了阻尼层的处理面积,模型振动响应峰值降低了16%以上,且并未显著增加阻尼处理的附加质量。研究结果表明:在聚氨酯–橡胶隔离复合阻尼材料的阻尼层厚度不变的情况下,增大隔离层与阻尼层的厚度比有助于提高复合阻尼材料的减振性能;分段式隔离层的设计能够进一步改善复合材料的阻尼性能。

Stand-off free layer damping is a vibration reduction treatment established on the traditional free layer damping structure.Based on the theory of stand-off free layer damping,polyurethane-rubber stand-off layer damping material was prepared by using rigid polyurethane foam as stand-off layer and rubber as damping layer for suppressing structural vibration.With considering the shear deformation of damping layer,the equation of motion for cantilever beam treated with the composite material was derived by the principle of modal superposition and Lagrange equation.The composite damping material with the thickness ratio of 1 to 3 and segmented stand-off layer was applied to the cantilever steel beam.The amplitude-frequency curves,loss factors,and mode frequencies were analyzed by the hammering test.The results showed that when the thickness ratio of the stand-off layer to the damping layer is increased from 1 to 3,the vibration response peaks of the model are reduced by 13%~62%and the loss factors are also increased obviously.When the ratio exceeds 1.5,the damping performance of the material on the low-order mode of the beams continues to increase,while the damping effect of the higher-order mode tends to be stable.As the results of the segmented stand-off layer,its bending stiffness is reduced and the processing area of the damping layer gets larger.The vibration response peaks of the models are reduced by more than 16%,while the additional mass of damping treatment is not significantly increased.It is concluded that the vibration reduction performance of the composite damping material could be better by increasing the thickness ratio of the stand-off layer to the damping layer,especially at low frequency.The design of segmental stand-off layer is helpful to further improve the damping performance based on composite materials.