The Effect of Stress-Wave Diffraction on Stress Measurements and a Concept for an Omnidirectional Dynamic Stress Gage.
An analysis of the transient response of the pressure in an embedded elastic inclusion due to an incident compressional wave. Also included in the study is an outline of a design for an omnidirectional pressure transducer with a response capable of being analyzed by the methods of the theory of elastic wave propagation and diffraction. The transducer proposed is an elastic spherical inclusion that is to be buried in the ground and is sensitive, through strain gages, to the mean stress or pressure at its origin. Both frequency response and transient behavior are treated. Two methods are given for determining total pressure response. One uses the calculus of residues and the high-frequency response and sums the resulting infinite series. The other solves the inverse problem by a Fourier transform method and finds the incident pressure in terms of the mean pressure at the center of the inclusion, for which an exact, explicit solution is found between successive reflections. The procedure could be used to decode the transducer output electronically. 58 pp. Refs. (MW)