Investigation of dynamics and vibration properties of sandwich structures with particle damper

With the development of computer technologies, engineering analysis and simulations, which were impossible or difficult before, have become easier. One of the tools developed for this purpose is the Discrete Element Method, which is a numerical modeling technique that allows the simulation of discontinuous materials consisting of many small particles. This method uses Newton's second law to calculate the position and velocity of each particle in a minor step by modeling each particle in the system as a rigid body. When particles collide with each other and with surfaces, they undergo elastic deformation and overlap slightly, and this overlap is used to calculate contact forces, treating each particle like a spring. In this thesis, vibration analysis of the structures with cells of different geometries moving on a horizontal axis excited from the base was carried out using the Discrete Element Method. The effects of parameters such as different particle numbers and cell sizes on the damping of the structure were investigated. Then, vibration analysis of continuous honeycomb layered beam with fixed-free boundary conditions modeled using Euler-Bernoulli theory was done with the help of Matlab® package program. The modal parameters of the layered beam were obtained from the Ansys® APDL package program. A specific region from the end of the beam is designated to place the particle dampers. The frequency response function was calculated by exciting the beam from its appropriate point with a random input force. The first four vibration modes are considered sufficient to calculate the effect of the particles on the damping of the beam. In the last stage, vibration analysis of the layered beam, which is assumed having fixed-free boundary conditions and rotates around a fixed hub, was carried out. The effect of different rotational speeds on vibration amplitude was investigated. As a result, it was observed that the impact particles significantly reduced the vibration amplitude of the structure. By placing the particles in local rather than general positions, their natural frequency changes very little.