Vibro-acoustic modeling of aircraft structures using Finite Element- informed Statistical Energy Analysis

Abstract

This paper addresses the problem of predicting the structure born and airborne sound transmission in aircraft using Statistical Energy Analysis (SEA). Often analytical formulations are used to approximate the SEA parameters. In the present prediction method, a finite element (FE)-informed SEA approach is employed. To compute the coupling coefficient, the structure is represented with a repetition of unit cell and an FE model of the unit cell is assigned to evaluate the direct field dynamic stiffness matrix of the SEA subsystems at the connections. An efficient strategy is employed to determine the equivalent material properties of the FE model. Thus, a two-dimensional unit cells of different constructions such as composite, sandwich, visco-elastic laminate and ribbed section sections can be used. To evaluate the equivalent properties of multilayers structures, each layer is assumed as thick laminate with orthotropic orientation. Moreover, rotational inertia and transversal shearing, membrane and bending deformations are accounted for. First order shear deformation theory is employed. The developed approach handles symmetrical layouts of unlimited number of transversal compressible or incompressible layers. The accuracy of this modeling approach is confirmed through comparison to alternate validated theoretical approaches. Representative examples of spacecraft structural response and interior noise predictions for typical load cases are shown and the use of SEA models as a tool for guiding construction of complex structures to meet acoustic performance targets and optimize designs are presented. Conclusions about the application and advantages of this approach is presented.