Accession Number : ADA199286

Title :   Final Report on Contract N00014-88-J-1072 (American Society for Engineering Education),

Corporate Author : AMERICAN SOCIETY FOR ENGINEERING EDUCATION WASHINGTON DC

Personal Author(s) : Jacobs, Laurence J.

Report Date : 1987

Pagination or Media Count : 15

Abstract : An investigation is made into analytical and experimental aspects of acoustic emission. Acoustic emission, a method of nondestructive evaluation, detects stress waves at a specimen's boundary and relates them back to the various internal events that occur within the body. By examining the mechanics of potential damage mechanisms, specific acoustic emission signals can be isolated and interpreted. This research included investigations into the uses of acoustic emission for the nondestructive testing of both isotropic and anisotropic (composite) materials. The goal was to investigate the mechanics of delamination crack growth, including the effect of friction, in composite materials. Friction is a major concern since it is a potential source of acoustic emission signals; previous research indicates that the fretting of fracture surfaces causes a significant amount of friction generated emission. The growth of delaminations is a significant factor when determining the structural integrity of a laminated composite element. An integral equation approach was formulated to analyze the problem. This solution will model an interface crack between two dissimilar anisotropic bodies. (JHD)

Descriptors :   *ACOUSTIC EMISSIONS, *STRESS ANALYSIS, *NONDESTRUCTIVE TESTING, *DAMAGE ASSESSMENT, ACOUSTIC SIGNALS, ANISOTROPY, COMPOSITE MATERIALS, CRACK PROPAGATION, CRACKS, DAMAGE, ENGINEERING, FRACTURE(MECHANICS), FRETTING, FRICTION, GROWTH(GENERAL), INTEGRAL EQUATIONS, INTERFACES, INTERNAL, LAMINATES, RELIABILITY, SEPARATION, SOURCES, STRESS WAVES, STRUCTURAL PROPERTIES, SURFACES.

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE