【作者】 胡溧；

【导师】 黄其柏；

【作者基本信息】 华中科技大学 ， 机械设计及理论， 2008， 博士

【摘要】 PD (Particle Damping)技术,又称颗粒阻尼技术,是二十世纪九十年代振动控制领域最新出现的一种微小颗粒阻尼减振技术。它主要通过在振动体的有限封闭空间中填充微小颗粒,利用微小颗粒之间的摩擦和冲击作用消耗系统的振动能量,达到减振目的。PD技术具有应用环境范围广、对原结构改动小、产生的附加质量小、减振效果显著等优点,因此对它的减振机理的研究已成为国内外振动界研究的热点之一。本论文主要研究PD的减振机理,并围绕影响其减振效率的若干关键因素,在理论推导、数值模拟、试验研究以及实验验证等多方面进行研究和探讨。论文回顾总结了与此研究相关的理论和技术的历史及发展现状,包括DEM、粉体力学、冲击阻尼、试验优化设计以及功率流等理论和实验等诸多内容。通过理论分析、数值仿真和试验设计相结合的方法,对PD的减振机理及其在减振领域的应用进行了有益的探索。论文首先详细阐述了三维离散元法的原理、算法,并建立了PD的DEM模型,利用所建立的DEM模型,分析讨论了影响PD减振特性的相关因素及其变化规律。通过试验研究的方法,揭示PD的一般减振机理。并在理论上,针对影响PD减振效率的主要内在因素之一的颗粒容器形状和尺寸,通过建立相关的PD粉体力学模型,研究外界激励力幅值和颗粒容器几何特征对其阻尼特性影响。在气-固两相流的理论基础上,分析了颗粒阻尼的内部作用力,建立了自由端部固定有颗粒阻尼的悬臂梁自由振动模型。研究了梁的振动响应,并通过实验证明所建立的研究模型是正确的。通过分析该模型的动态响应研究了颗粒阻尼的耗能特性,并用颗粒阻尼的阻尼损耗因子描述了该特性。最后通过进一步分析不同条件下的颗粒阻尼的耗能得出一些有意义的结论。针对影响PD减振特性的主要内在因素——颗粒材料密度、颗粒粒径和体积百分数,通过二次回归正交组合试验设计,建立PD的试验回归模型并探讨了此三个因素对PD减振特性的影响规律和因素之间的交互作用,还利用非线性优化理论与方法对PD的参数进行了优化设计,实验证明了优化结果的合理性。采用功率流法来研究PD在薄板上的分布位置对薄板振动的影响规律。通过对PD薄板结构采用离散建模方法,建立了PD板的振动方程,并利用Laplace变换的方法求解方程得到PD板功率流的相应表达式。并对所建立的模型进行了分析讨论,得到一些重要的规律。最后对PD器和薄板的阻尼损耗因子进行试验测量,同时提出PD板结构的实验方法,通过实验得到PD板结构的输入功率流和传递功率流,并与理论计算值进行了比较,验证理论分析中功率流模型以及由此得出的有关规律的有效性和正确性。总之,本文充分考虑了PD减振机理的复杂性,通过理论分析、数值仿真和试验设计以及实验研究相结合的方法,深入探讨了PD的减振机理,为其工程应用提供了一定的理论依据和指导原则。本文的研究成果,对于推动PD在低频减振降噪的应用方面具有重要的理论意义和工程价值。更多还原

【Abstract】 PD (Paritcle Damping) technology is also called powder damping technology. It is a new particle damping technology developed since 1990’s in the field of vibration control. Particles are packed into a sealed container. The vibration energy of the system is dissipated by the frictional and impact movement of the particles, so the vibration is attenuated gradually. It has a lot of advantages such as: it can be used in wide range environment, the structures of original system are modified very little, the effect of vibration absorption is notable, additional mass added to the original system is very little, etc. These advantages attracted more and more attention of scholars from different fields. A new concept of particle damper is put forward based on the vibration characteristics of PD in the dissertation. And the theoretical analysis, numerical simulation and vibration experiment are combined to study the key factors that influence vibration characteristics of PD. The development history and current situation of DEM, powder mechanics, impact damping, optimization of experiments and power flow have been reviewed in the thesis. Some helpful exploration about the vibration characteristics of PD in the field of vibration isolation have been carried out by combining theoretical analysis, numerical simulation with vibration isolation experiment.Considering the complexity of the research, the DEM model of PD is established based on the principles and algorithm of DEM. Moreover, the main factors that influence the damping ratio is picked out and the variation regularities are disclosed.The characteristics of PD are explored through the experiment method. The powder mechanics model of PD including the shape and dimension of the container -one of the main factors is established. The effects of the stimulation force and dimension of the containers on the damping efficiency are studied by the model.The inner force of in PD is studied and the vibration model is built based on the theory of multi-phase flow. The correctness of the model is testified. The damping characteristics of PD are studied through analyzing the dynamic response of the system. The special damping capacity of PD is used to describe the characteristics. Furthermore, some meaningful conclusions are drawn by study the capacity under different conditions.Orthogonal experiment design is carried out including the factors of the density and diameter of particles and packing ratio to establish the regression model of PD in order to study the other main factors’effects and the interaction between the factors. The design parameters are optimized based on the non-linear optimum design.The effects of the PD distribution are studied through the power flow method. The vibratory responses of the stiffened plate with PD are solved by using the Laplace transmission method, and the corresponding mathematical expressions of vibration power flows are proposed. The vibration power flows of the structures with different kinds of ribs and under various load locations are numerically analyzed. Theoretical and experimental studies show that the peak values of power flows and the transmission power flows can be restrained in case of the container being filed with particles, and the energy can be received easily from the vibration source with PD at the stimulating point rather than the other locations.At last, the damping ratio of PD and the plate without PD are measured by experiments. The input power flows and the transmission power flows are measured in order to verify the correct and efficiency of the theoretical deduction of last chapter.In summary, the vibration attenuation performances of PD are analyzed in details by theoretical analysis, numerical simulation and experimental study in the dissertation, which has offered some theoretical foundation and governing principle for practical application. The research results have important theory significance and engineering application value for promoting PD in reducing vibration and lowering noise at low frequency.更多还原