Passive Vibration Control of a Flat Panel via Topology Optimization of Damping Material using Structural Intensity

Abstract

Vibration energy exists in all structures (automobiles, home appliances, ships, aircraft, etc.) where external dynamic loads act and can be derived from engine operation or contact between machine parts. It is essential to identify and control the vibration energy because this vibration energy causes acoustic vibration problem, fatigue, crack of the component. It is necessary to identify the transmission path of the vibration energy to effectively control the vibration energy. Structural Intensity (SI) is used to investigate the vibration characteristics of the structure from a practical point of view since it can indicate the magnitude and direction of the vibration energy flow at any location of the structure. SI combines the effects of force, velocity amplitude, and relative phase angle so that the vibration characteristics of the structure can be accurately predicted, which is important for vibration control. The purpose of this study is to investigate the characteristics of vibration energy distribution and to perform passive vibration control of a flat panel via topology optimization of damping material using SI. The damping material used in this study is constrained layer damping (CLD). Among the passive vibration control techniques, CLD is widely used in various industrial applications. Typically, a viscoelastic or other damping layer is sandwiched between two stiff layers (usually a stiffer material such as aluminum). When the system flexes during vibration, shear strains develop in the damping layer and energy is lost through shear deformation of the material. The advantages of using CLD are the high loss factors with relatively thin configurations and that the stiffness of the composite system is not significantly increased. The optimization problem is performed for two purposes: to concentrate and reduce vibration energy at specific locations of the structure. The optimization technique used is topology optimization that optimizes material layout within a given design space, for a given set of loads, boundary conditions and constraints with the goal of maximizing the performance of the system. The objective function of the optimization problem is the magnitude of the SI representing the magnitude of the vibration energy, and the design domain is the damping layer attached to the flat panel. In this study, the optimization results were applied to the 3M damping foil used in actual industrial structures and the results were verified by experiments. Verification was performed with the velocity of the flat panel measured using the Laser Scanning Vibrometer (LSV).