Accession Number : AD0744317

Title :   Limits to the Detection of Small Internal Voids in Solids with Holographic Techniques.

Descriptive Note : Research memo.,

Corporate Author : GRUMMAN AEROSPACE CORP BETHPAGE N Y RESEARCH DEPT

Personal Author(s) : Pernick,Benjamin J.

Report Date : JUN 1972

Pagination or Media Count : 87

Abstract : The ability to find small voids in acoustically excited solid specimens using coherent optical detection methods is limited by three factors: available ultrasonic power levels, acoustical and optical noise elements, and nonlinear properties of the working materials. Constraints on the detection sensitivity due to ultrasonic power limitations are established in this memorandum. A void embedded in an elastic halfspace is used as a physical model. Deformations of the free surface due to void-scattered ultrasonic waves are derived and illustrated for several void sizes and depth locations. Properties of the liquid layer that influence the magnitude of signal amplification and sources of systematic distortions due to nonlinearities are determined from the fundamental fluid dynamic equations. Several holographic techniques to observe the liquid surface profile are discussed. (Author)

Descriptors :   (*NONDESTRUCTIVE TESTING, ULTRASONIC RADIATION), (*DEFECTS(MATERIALS), ACOUSTIC DETECTORS), METALS, AIRFRAMES, MECHANICAL WAVES, COMPUTER PROGRAMS, ACOUSTIC IMPEDANCE, TEST METHODS, STEREOPHOTOGRAPHY

Subject Categories : Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE