Vibration damping using low-wave-speed media with applications to precision machines
Vibration damping using low-wave-speed media with applications to precision machines
复制标题
使用低波速介质进行减振并应用于精密机器
DOI：
--
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
K. Varanasi
中科院分区：
文献类型：
--
作者：
K. Varanasi
振动和噪声是大多数机械系统中始终存在的问题，从消费产品到精密制造系统。但是，大多数抑制振动的方法都是昂贵的和侵入性的，因此只有一小部分研究实验室开发的技术被广泛应用。在本文中，我们提出了一种新的基于波的阻尼方法来抑制机械和结构的振动。我们的研究表明，通过结构与低密度、低波速介质（如泡沫或粉末）之间的动态相互作用，可以在很少增加质量的情况下获得显著的宽带阻尼。这种阻尼现象在许多应用中都有很大的前景，因为它是坚固的（即不调谐），不会在结构中引入显着的蠕变，可以适应大应变，并且可以使用重量轻，成本低，耐用，对温度不敏感且易于包装的材料来实现。我们报告了几个实验，其中弯曲和纵向振动是用这种方法衰减。低密度粉末填充结构的弯曲振动实验表明，在较宽的频率范围内，获得了高阻尼（对于质量为梁质量2.3%的粉末填充，其损失因子高达12%）。有些令人惊讶的是，在很宽的幅度范围内，发现响应是线性的。我们提出可以将粉末建模为压力波可以在其中传播的流体，并发现该模型与实验结果吻合得很好。这些发现表明，任何波传播速度足够低的中等损耗介质都可以用来获得类似的响应。我们发现，与结构耦合的低密度泡沫在更宽的频率范围内表现出可比的衰减，并且如果模型中包含膨胀波和剪切波，则可以准确预测响应。我们开发了这些现象的简化模型，从而获得了包含低波速介质的结构设计指南。将该方法与其他阻尼技术进行了比较，并描述了在皮带驱动定位系统和精密挠性组件中的应用。论文导师：Samir A. Nayfeh头衔：机械工程助理教授论文委员会：Samir A. Nayfeh教授Warren P. Seering教授Alexander H. Slocum教授David L. Trumper
Vibration and noise are an ever-present problem in the majority of mechanical systems, from consumer products to precision manufacturing systems. But most approaches for vibration suppression are expensive and invasive, so only a small subset of the techniques developed in research labs are widely used. In this thesis, we present a novel wave-based damping approach for the suppression of vibration in machines and structures. Our studies show that significant broad-band damping can be attained with little added mass via dynamic interaction between a structure and a low-density, low-wave-speed medium (such as a foam or powder). This damping phenomenon has great promise for many applications because it is robust (that is, not tuned), does not introduce significant creep into a structure, can accommodate large strains, and can be realized using materials that are light weight, low cost, durable, insensitive to temperature, and easy to package. We report on several experiments in which flexural and longitudinal vibration are attenuated using this approach. Experiments on flexural vibration of structures filled with low-density powder show that high damping is obtained (with loss factors as high as 12 percent for a powder fill whose mass is 2.3 percent of that of the beam) over a broad frequency range. Somewhat surprisingly, the response is found to be linear over a wide range of amplitudes. We propose that the powder can be modeled as a fluid in which pressure waves can propagate and find that such a model matches the experiments well. These findings suggest that any moderately lossy medium in which the speed of wave propagation is sufficiently low can be used to obtain similar responses. We find that low-density foams coupled to structures exhibit comparable attenuations over a somewhat broader frequency range, and that the responses can be accurately predicted if dilatation and shear waves are included in the model. We develop simplified models for these phenomena, and thence obtain guidelines for design of structures incorporating low-wave-speed media. The approach is compared to other damping techniques, and applications to beltdriven positioning systems and precision flexure assemblies are described. Thesis Supervisor: Samir A. Nayfeh Title: Assistant Professor of Mechanical Engineering Thesis Committee: Prof. Samir A. Nayfeh Prof. Warren P. Seering Prof. Alexander H. Slocum Prof. David L. Trumper