This presentation was made at CAASE18, The Conference on Advancing Analysis & Simulation in Engineering. CAASE18 brought together the leading visionaries, developers, and practitioners of CAE-related technologies in an open forum, to share experiences, discuss relevant trends, discover common themes, and explore future issues.

Resource Abstract

Plates are initially flat structural components bounded by two parallel faces. Because of several structural advantages, plates are used in bridges, airplanes, automobile, missiles, ships and machine parts. Surface damping treatment is used to solve resonant noise and vibration problems associated with plates. One of them is constrained layer damping treatment, where viscoelastic layer is sandwiched between base plate and a stiff constraining layer. Constrained damping treatment is widely used in automotive components such as dash panel, oil pan, rear wheel wells to reduce unwanted vibration and noise levels. Moreover, using constrained layer damping on the automobile components reduce complexity, weight and cost compared the traditional NVH treated components. Therefore, modeling of components covered with constrained layer damping is vital to optimize thicknesses of lower, middle and upper layers. In this study, dynamic response of plates partially covered with constrained layer damping treatment is studied using ANSYS Parametric Design Language (APDL). Geometry of base plates, viscoelastic and constraining layers, mesh density, material properties, boundary conditions are modeled parametrically using ANSYS APDL. Since mechanical properties of viscoelastic materials are affected by operating temperature, shift factor is calculated using Arrhenius Model to take operating temperature into account. Complex modulus and loss factor for each interested frequency is computed using Ross, Kerwin and Ungar (RKU) equations. In the light of above information, the program calculates desired natural frequencies and mode shapes. Moreover, frequency response function of plates are calculated for interested frequency range. Besides, the efficiency of constrained layer damping treatment is examined in detail by comparing dynamic response of both damped and undamped plates. In the second part of this study, parametric finite element model is verified using analytical formulations, where dynamic response of beam covered with constrained layer damping treatment is computed using continuous beam formulations. Both analytical and finite element methods are compared for a simple case. After verification of parametric finite element model, several case studies are conducted to determine optimum design for different boundary conditions by changing thickness and location of both viscoelastic layer and constraining layer. As a conclusion, dynamic analysis of plates covered with constrained layer damping treatment using parametric finite element method is time saving compared to traditional analysis techniques since different materials, boundary conditions, thickness of both viscoelastic and constraining layers are simulated by changing only relevant parameters in the script.