Stand-off free layer damping is a vibration reduction method based on the traditional free layer damping. In this paper, a stand-off free layer damping cantilever beam is prepared with the steel plate as the base layer, rigid polyurethane (PU) foam as the stand-off layer, and rubber as the damping layer, and the motion equation of the cantilever beam is derived. The dynamic mechanical properties of damping rubber and PU foam are tested and analyzed. Through hammering tests, we have studied the effect of the density and thickness of the PU foam layer on the amplitude-frequency curves, modal frequencies, and loss factors of the cantilever beams. The results show that the rubber damping material is a major font of energy dissipation of the cantilever beam, and PU foam acts mainly to expand the deformation of the damping layer and plays a role in energy consumption. By increasing the density and thickness of PU foam within a certain range, the vibration peaks of the first five modes of the cantilever beam decreases gradually, the loss factors rise, and the damping performance is improved. Meanwhile, increased density and thickness enhances the overall stiffness of the beam, making the modal frequencies get higher.

中文翻译：

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聚氨酯泡沫支座层对支座自由层阻尼悬臂梁减振性能的影响

支座自由层阻尼是一种基于传统自由层阻尼的减振方法。本文以钢板为基层，以硬质聚氨酯泡沫为支撑层，以橡胶为阻尼层，制备了支撑自由层阻尼悬臂梁，其运动方程为得出悬臂梁。测试并分析了阻尼橡胶和PU泡沫的动态力学性能。通过锤击测试，我们研究了聚氨酯泡沫层的密度和厚度对悬臂梁的幅频曲线，模态频率和损耗因子的影响。结果表明，橡胶阻尼材料是悬臂梁能量耗散的主要形式，PU泡沫主要起到扩大阻尼层变形的作用，并起到能耗的作用。通过在一定范围内增加PU泡沫的密度和厚度，悬臂梁的前五个模态的振动峰值逐渐减小，损耗因子增大，阻尼性能得到改善。同时，增加的密度和厚度可以提高梁的整体刚度，从而使模态频率更高。