Acoustic response of thin-walled, orthogonally stiffened cylinders

D Zhao,G Squicciarini,N S Ferguson

doi:10.1088/1757-899x/657/1/012007

Abstract

A semi-analytical model is developed to predict the acoustic response of thin-walled, orthogonally stiffened cylinders. The free vibration model is solved by the approximate assumed-modes method. The excitation of the normal modes is considered in terms of the Joint Acceptance Function (JAF) for incident acoustic harmonic plane waves. The surface pressure distribution is obtained by the shallow shell approximation, where the blocked excitation pressure is double the incident pressure, and by the 2-D rigid cylinder approximation considering the sound scattering. The acoustic response is then compared with that of a fully coupled FE-BE model. An efficient estimation of the response can be obtained by the two models over a certain range of accuracy. Numerical results for different structural configurations are then given. The effect of the stiffeners on the modal characteristics is discussed. It also illustrates the modal contribution to the total displacement response and addresses both circumferential and axial orthogonally stiffened cylinder arrangements.

Highlights

Thin-walled, stiffened cylinders are representative of widely used aerospace structures
The excitation of the normal modes is considered in terms of the Joint Acceptance Function (JAF) for incident acoustic harmonic plane waves
The acoustically excited modes can be characterized by a structure-acoustic coupling ratio, the Joint Acceptance Function (JAF), which effectively relates the modal forces to the spatial matching between the acoustic field and the structural mode [4]

Summary

Introduction

Thin-walled, stiffened cylinders are representative of widely used aerospace structures. The acoustic response of stiffened plates has been analysed in a recent study by the authors [5] These assumptions are not necessary applicable for curved structures. Published under licence by IOP Publishing Ltd coupled vibroacoustic analysis, usually provided using a model that combines the structural model (FEM) and the acoustic domain (BEM) This approach requires high computational resources and it is not always practical for preliminary investigation and parametric study. The subsequent modal forces are derived based on two approximations for the pressure distribution: (i) blocked pressure around the cylinder and (ii) 2-D scattered pressure These approaches are compared with the results of a fully coupled vibroacoustic analysis from a FE/BE model.

Rigid baffle

Symbol rltρνβ

Conclusions