Numerical simulation of structural acoustics using coupled finite element and boundary element techniques

The primary objective of this dissertation is directed towards the development of a methodology associated with a numerical simulation model capable of solving coupled structural-acoustic problems. These problems may include vibrating structural components involving plates, shells and frames (acting as stiffeners) interacting with a single or multiple acoustic fluid domain. The structural components are modeled using a finite element method (FEM) formulation while the acoustic domain is modeled using a boundary element method (BEM) formulation. Implementations based on a collocation based Direct BEM (DBEM) as well as a variational technique based Indirect BEM (IBEM) are developed and studied in this research. A normal decomposition scheme is used for the structural system leading to an efficient coupling algorithm combining the finite element and boundary element systems. While the coupled IBEM is limited to using a single acoustic fluid, the coupled DBEM can work on multiple fluid and multiple region applications and thus provides a very powerful numerical tool. Various structural and acoustic boundary conditions and loading specifications, along with the capability of providing various symmetry conditions, enhances the scope of the current development in solving complex coupled problems in structural acoustics.; All of the current development has been implemented in a general purpose boundary element solution technique (GPBEST) computer program. A wide variety of problems are included in this work, some of which are validation examples while others are application problems, to illustrate the applicability and accuracy of the numerical schemes involved. The power of the multi-region and multi-fluid coupled DBEM has not been harnessed to its fullest extent till now in any technical literature and forms the core essence of the current research.