For the vast majority of geometries and problems, these PDEs cannot be solved with analytical methods. Instead, an approximation of the equations can be constructed, typically based upon different types of discretizations. These discretization methods approximate the PDEs with numerical model equations, which can be solved using numerical methods.
In this paper, the theory of the energy finite element method for interior noise prediction is reviewed first. This is followed by the investigation of two example problems using EFEM; a the interior noise of an airplane cabin and b the sound transmission loss of a dash.
Further, the advantages of EFEM in the solution of high frequency vibroacoustic problems are discussed.
Technical Paper A hybrid method is developed by combining energy finite element method EFEM and energy boundary element method EBEM to predict interior noise of structural-acoustic systems at high frequencies.
The structural vibration response is computed from EFEM. The interior sound pressure level in the acoustic domain is recovered using EBEM. To validate the hybrid method, the interior noise levels in simplified airplane cabin and van models are computed and compared with that of EFEM only model.
Good correlations are observed. The formulation was subsequently extended to model noise control treatments by incorporating appropriate modifications to structural-acoustic and acoustic-acoustic joint matrices.
The formulations developed are implemented and the resulting computer program was validated by comparing the predictions from the present development to the results from alternative methods.
Technical Paper The relationship between the acoustical performance and macroscopic material properties of elastic porous materials, based on modified Biot's theory, is used to develop sensitivity relationship among acoustic and macroscopic material properties.
The sensitivity information are normalized scaled and subsequently used to improve and tune the acoustical performance of elastic porous materials. Example problems are used to demonstrate the applicability of the technique.
Technical Paper Thermo-chemical-mechanical TCM feedstock conversion FC systems originally developed for high temperature conversion of domestic solid feedstock or blends to useful liquid and gaseous fuels are examined for advanced life support ALS applications in spacecraft. Recently, exploratory investigations with these TCM-FC systems to use or sequester CO2 have led also to a focus on the production of useful chemicals and chars activated carbon, humates, CO2 scrubbers, chelating and detoxifying agents, etc.
TCM systems can process solid blends with catalysts, adsorbants, reactants, carbon dioxide, steam, air, oxygen, natural gas and liquids. TCM units are extrusion systems, and are more adaptable to zero gravity than fluidized bed systems or other systems that rely on gravity.The Energy Finite Element Analysis (EFEA) is a finite element based computational method for high frequency vibration and acoustic analysis .
The EFEA solves with finite elements governing differential equations for energy variables. These equations are developed from wave equations. Recently, an EFEA method for computing high frequency vibration of structures either in vacuum or in . Abstract A hybrid method is developed for predicting the high-frequency vibration response of fluid-loaded cylindrical shells with periodic circumferential stiffeners.
In this method, the cylindrical shell is modeled using the Energy Finite Element Analysis (EFEA) method which includes added mass and radiation effects due to the surrounding. Energy Finite Element Method (EFEM) is an alternative method to currently practiced Statistical Energy Analysis (SEA) for the solution of high frequency vibro-acoustic problems.
In this paper, the theory of the energy finite element method for interior noise prediction is reviewed first.
The energy finite element method (EFEM) is used to predict structural–acoustic responses in the high frequency range, where the coupling between structural junctions and the structural–acoustic interface are modelled using power transfer coefficients.
A high-frequency shock response analysis method based on energy finite element method and virtual mode synthesis and simulation CHEN Zhaolin 1, YANG Zhichun 1, . ENERGY FINITE ELEMENT METHOD FOR HIGH FREQUENCY STRUCTURAL-ACOUSTIC PROBLEM Energy Finite Element Method (EFEM) The governing equation for EFEM was derived by Nefske and Sung for beams , Bouthier and Bernhard for plates [19,20,21], and Bitsie for acoustic space .