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31 May 1996 Control of sound radiation from a NITINOL-reinforced plate into an acoustic cavity
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The sound radiation from vibrating NITINOL-reinforced plates coupled with acoustic cavities are controlled by heating sets of shape memory alloy (NITINOL) fibers embedded along the neutral planes of these plates. Thermal, dynamic and acoustic finite element models are developed to study the fundamental phenomena governing the coupling between the dynamics of the NITINOL plates and the acoustic cavities. The models are used to compute the frequencies, mode shapes and sound radiation for different initial tensions and activation strategies of the NITINOL fibers. The predictions of the models are validated experimentally using a square glassfiber/polyester resin plate, whose sides are 19 cm and thickness is 0.254 cm, mounted on a 19 cm X 19 cm X 38 cm cavity. The plate is reinforced with 58 NITINOL fibers that are 0.55 mm in diameter which are embedded inside vulcanized rubber sleeves placed at the plate mid-plane. The results obtained indicate close agreement between the theory and experiments. Also, it is shown that activating all the NITINOL fibers results in increasing the first mode of vibration from 240 Hz to 277.5 Hz and increasing the corresponding loss factor from 0.014 to 0.039. Such significant shift of the modal characteristics of the plates results in suppressing the amplitude of vibration of the plate by 76% and attenuating the sound pressure level radiated inside the cavity by 62%. Therefore, the experimentally validated theoretical models presented in this paper provide invaluable means for predicting sound radiation from NITINOL-reinforced plates in coupled acoustic cavity.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jeng-Jong Ro and Amr M. Baz "Control of sound radiation from a NITINOL-reinforced plate into an acoustic cavity", Proc. SPIE 2715, Smart Structures and Materials 1996: Mathematics and Control in Smart Structures, (31 May 1996);

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