In Part I [Turek et al.] a numerical solution for a two-body acoustical multiple scattering problem based on the analytical infinite series solution of the wave equation was presented. Surface and far-field solutions involv- ing permutations of the two ‘‘degenerate’’ boundary conditions (pressure release and rigid) were compared to solutions obtained with the combined Helmholtz integral equation formulation problem (CHIEF) program. In this paper the case in which one of the spheres is fully elastic and the other pressure release is modeled and the results verified experimentally.
A numerical solution for a two-body acoustical multiple scattering problem based on the analytical infinite series solution of the wave equation was developed. FORTRAN 77 codes implementing this solution were written which are capable of simulating the case of two spheres of arbitrary radius and distinct material properties subject to an acoustic plane wave of arbitrary incidence. Far-field solutions involving permutations of the two ‘‘degenerate’’ boundary conditions (pressure release and rigid) were compared to solutions obtained with the combined Helmholtz integral equation formulation problem (CHIEF) program. Surface pressures and velocities were also calculated. [Work supported by ONR.]
The applicability of matched-field processing (MFP) [Baggeroer et al., IEEE J. Ocean. Eng. 18, 401–424 (1993)] techniques to localize sources of vibration in structures and to perform nondestructive testing is explored. MFP is a generalized procedure of array processing used in ocean acoustics to either localize sources or perform inversions. MFP involves correlations between the solutions (or ‘‘replicas’’) of the wave equation for a given acoustic model of the ocean and the data measured at an array of sensors. The correlations are made using an assortment of linear and nonlinear methods. These techniques were successfully tested using simulation for the relatively simple problem of localizing a harmonic point force on a simply supported laterally vibrating beam. Wave equation solutions for describing the vibration of more complicated structures (simulated by adding spring constraints to the beam) become, at some point of complexity, intractable. Often statistical techniques provide the only practical description of such structural vibration problems. Multiple constraint MFP methods, tolerant to solution mismatch, were used to deal with these more complicated structures. Finally, it was demonstrated that MFP methods might also be used as a means of nondestructive testing in order to locate defects.
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