Particle Dampers – Vibration Modification by Distributed Dissipation originating from Complex Particle Shapes and Fluid/Solid Interactions

粒子阻尼器的应用是一种很有前途的振动调节方法。颗粒阻尼器在很大的频率范围内工作，它们涵盖了额外的功能，如最小化噪音或作为承重部件，而它们非常坚固，适用于更大的温度范围。几种物理现象对粒子阻尼器起着重要的作用，并相互作用以实现阻尼器的特性。到目前为止，还没有令人满意的预测模拟方法考虑到所有这些物理过程的相互作用，这样做可用于对粒子阻尼器的理解进行适当的研究。该项目的目的是更深入地了解粒子阻尼器的优化设计。颗粒阻尼器功能的一个重要点是颗粒和外壳之间的大量接触。因此，在这个项目中，粒子是用离散元法（DEM）建模的。由于颗粒桩的无网格特性，可以模拟颗粒桩的大瞬态位移。为了影响耗散，用非凸粒子代替了简单的球体。在第一步中，将开发用于在这些粒子之间施加摩擦的算法。一项适当的科学调查通常基于两个支柱：模拟和实验。我们要在每一个工作任务中进行小实验；主动实验用激振器刺激，被动实验用摆锤刺激。除了粒子的复杂形状外，我们还想开发一种新的方法来预测由于粒子撞击而产生的声音。这样，就有可能优化一个更智能的阻尼器，用于降低工作机器的噪音，考虑到噪音本身的水平，同时产生的能量耗散。另一点是由固体颗粒和流体的混合物组成的阻尼器的填充。因此，流体（由光滑粒子流体动力学建模）与颗粒耦合的经验将用于开发非凸颗粒与流体耦合的新方法。该方法用于研究加入一定量流体对能量耗散的潜在改善。损伤在许多技术应用中起着重要作用。最后但并非最不重要的是，我们想在DEM中实现一个简单的损伤方法，在相邻的粒子和外壳之间，并以这种方式研究损伤对阻尼的影响。

The application of particle dampers is a promising alternative for the modification of vibrations. Particle dampers are working over a large frequency range, they cover additional functions like minimizing noise or being a load bearing part, whereas they are very robust and are applicable over a larger temperature range. Several physical phenomena playing an important role for particle dampers and are interacting to fulfill the features of the damper. Until now there is no satisfying predictive simulation approach which takes the interaction of all those physical processes into account and in doing so is useable for a proper investigation for the understanding of particle dampers.The aim of this project is the more profound understanding of particle dampers for an optimal design. One of the important points for the functionality of a particle damper are the numerous contacts in between the particles and the housing. Therefore, in this project the particles are modeled with the Discrete Element Method (DEM). Due to its mesh-free character it is possible to model the large transient displacements of the particle pile. For influencing the dissipation simple spheres are replaced with non-convex particles. In a first step an algorithm for applying friction between those particles will be developed. A proper scientific investigation is often based on two pillars: simulation and experiment. We want to carry out small experiments in every working task; active experiments with stimulation via a shaker and passive ones with a pendulum. Besides the complex shape of the particles we want to develop a new method to predict the production of sound due to the impact of particles. In doing so, it is possible to optimize a smarter damper which is used for reducing the noise of a working machine, regarding the noise level by itself and simultaneously the resulting energy dissipation. Another point is the filling of the damper consisting of a mixture of solid particles and a fluid. Therefore, the experience in coupling a fluid (modeled by Smoothed Particle Hydrodynamics) with particles will be used to develop a new approach for coupling non-convex particles with a fluid. This approach is used to investigate the potential improvement of energy dissipation when a certain amount of fluid is added. Damage plays an important role in many technical applications. Last but not least we want to implement a simple damage approach into the DEM, between adjacent particles and also the housing and in this way to investigate the influence of damage to the damping.