Energy Finite Element Analysis Developments for High Frequency Vibration Analysis of Composite Structures.

Abstract

Energy finite element analysis (EFEA) has been proven to be an effective and reliable tool for high frequency vibration analysis. It uses the averaged energy density as the primary variable to form the governing differential equations and provides a practical approach to evaluate the structural response at high frequencies, which is hard to reach with conventional finite element analysis because of the computational cost. In the past, EFEA has been applied successfully to different structures, such as beams, rods, plates, curved panels etc. Until recently, however, not much work has been done in the field of composite structures. Research for developing a new EFEA formulation for modeling composite laminate plates is presented in this dissertation. The EFEA governing differential equation, with the time- and space- averaged energy density as the primary variable, is developed for general composite laminate plates. The power transmission characteristics at plate junctions of non-isotropic materials, including orthotropic plates and composite laminate plates are studied in order to obtain the power transmission coefficients at the junction. These coefficients are utilized to compute the joint matrix that is needed to assemble the global system of EFEA equations. The global system of EFEA equations can be solved numerically and the energy density distribution within the entire system can then be obtained. The results from the EFEA formulation have been validated through comparison with results from very dense FEA models.