INVESTIGATION OF A METHOD FOR ATTENUATING PLANE WAVES IN BARS.
MINNESOTA UNIV MINNEAPOLIS DEPT OF AERONAUTICS AND ENGINEERING MECHANICS
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The mathematical analysis developed for Attenuation of Plane Waves in Semi-infinite Composite Bars, R. Plunkett and C. H. Wu, J. Acoust. Soc. Am. 37, 28-30 1965 was verified experimentally. Traveling compressive waves in bars can be attenuated effectively by a composite configuration consisting of serrated septa bonded to the bar by layers of viscoelastic, dissipative adhesive. Attenuation depends on the ratio of sonic velocities of the septa and the bar, frequency, relative dimensions, and the complex shear modulus of the adhesive. Configurations of septa with low effective sonic velocity and zero sonic velocity were tested on square bars and I-beams. Agreement between calculated and experimental attenuation factors is shown. Factors necessary for optimum attenuation are also discussed. Author