Mechanical Engineering Commons^™

Use Of Dimpling Techniques To Alter The Vibration And Acoustic Characteristics Of Beams And Plates, Mofareh Ghazwani

Dissertations

Structures such as beams and plates can produce potentially high levels of unwanted vibrations and noises in the environment. A method for improving the vibroacoustic characteristics of structures based on creating dimples on its surfaces is presented in this study. The goal of this technique is to keep the mass of the subject structure the same while changing its vibration and sound radiation characteristics. A boundary value model (BVM), derived using Hamilton’s Variational Principle, is used for modeling dimpled beams subjected to various boundary conditions. Using this method, the non-dimensional equations of motion, boundary conditions, and continuity conditions for a …

Analysis Of Vibroacoustic Properties Of Dimpled Beams Using A Boundary Value Model, Kyle R. Myers

Dissertations

Attention has been given recently to the use of dimples as a means of passively altering the vibroacoustic properties of structures. Because of their geometric complexity, previous studies have modeled dimpled structures using the finite element method. However, the dynamics of dimpled structures are not completely understood. The goal of this study is to provide a better understanding of these structures through the development of a boundary value model (BVM) using Hamilton's Variational Principle. The focus of this study is on dimpled beams, which represent the simplest form of a dimpled structure.

A general model of a beam with N …

Vibration-Induced Densification Of Granule Materials, Ninghua Zhang

Dissertations

Physical experiments as well as discrete element simulations of vibration are carried out. The use of different amplitudes and frequencies are applied in the experiments to facilitate the observation of densification trends with mono-disperse acrylic spheres and multi-disperse polyethylene pellets. For mono-disperse acrylic spheres, four densification trends are found at different vibration conditions, and attaining the "maximum density" is closely related to the combination of vibration frequency and amplitude, in agreement with experiments in the literature. For multi-disperse polyethylene pellets, there is a substantial increase in solids fraction due to the effects of particle shape and surface friction. Computer simulations …