ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

4aSA7. Influence of local static stress on structural acoustics: Experiment and modeling.

Hareen K. Gangala

J. Adin Mann, III

Aerosp. Eng. and Eng. Mech., 2019 Black Eng. Bldg., Iowa State Univ., Ames, IA 50011

An experimental setup was designed to locally introduce stresses in a steel beam. The far-field sound power radiated by the beam was experimentally calculated for various magnitudes of the induced stresses. As a model, a finite element code was developed for the equation of motion due to a modified theory of acoustoelasticity [Pao et al., J. Appl. Mech. 58, 11--17 (1991)]. The theory allows the static stress components to be additions to the elastic moduli of the body. The sound power radiated by a beam was calculated from the FEM model results for axial, transverse, shear, and combined distributions of the stress components. Experimental results showed that the sound power increased by up to 1 dB as the static stress was varied. Results from the FEM model showed that all the individual stress components contribute to the radiation and the combined effect was about a 1 dB increase in the radiated power. Both experimental and model results suggest that static stresses induced by discontinuities such as welding and bolting can play a role in the mechanisms of the sound radiation at a discontinuity in a structure. [Work supported by ONR.]