Accession Number : ADA302361

Title :   Ultrasonic Characterization of the Nonlinear Elastic Properties of Unidirectional Graphite/Epoxy Composites.

Descriptive Note : Contractor rept.,

Corporate Author : JOHNS HOPKINS UNIV BALTIMORE MD

Personal Author(s) : Prosser, William H.

PDF Url : ADA302361

Report Date : OCT 1987

Pagination or Media Count : 200

Abstract : Because of their high strength and stiffness together with their light weight, fiber reinforced composite materials offer great potential for applications particularly in the aerospace industry. The weight savings translate into increased performance and decreased fuel costs. In addition, the use of these materials avoids the dependence on foreign sources for the critical elements needed in the new exotic metallic alloys that otherwise nbght be used. Early research has proven the usefulness of these materials, but the need to quantitatively characterize important material properties and develop applicable nondestructive evaluation techniques remains. Important physical properties (i.e. mechanical, thermal, electrical) need to be measured. Moreover, relationships between these physical properties and important engineering properties such as strength, residual strength after impact and fatigue loading, and fiber-matrix interfacial strength need to be examined to provide a basis for quantitative nondestructive evaluation of these materials. Toward this goal, linear and nonlinear elastic properties have been demonstrated to be important physical properties in conventional materials. In particular, nonlinear properties are important in the nondestructive determination of applied and residual stress (strain) as well as measuring the interatomic bonding forces in crystalline solids. Also, several investigations have established a possible relationship between nonlinear elastic properties and ultimate strength in aluminum and carbon steel. (MM)

Descriptors :   *FIBER REINFORCED COMPOSITES, *GRAPHITE EPOXY COMPOSITES, STRESS STRAIN RELATIONS, COMPUTER PROGRAMS, NONDESTRUCTIVE TESTING, PHYSICAL PROPERTIES, COMPOSITE MATERIALS, LOADS(FORCES), STIFFNESS, ELASTIC PROPERTIES, MODULUS OF ELASTICITY, MATRIX MATERIALS, CRYSTALS, ALLOYS, STRENGTH(MECHANICS), COSTS, HIGH STRENGTH, ALUMINUM, LEAST SQUARES METHOD, RESIDUAL STRESS, LIGHTWEIGHT, TRANSDUCERS, FATIGUE(MECHANICS), NONLINEAR ANALYSIS, AEROSPACE INDUSTRY, WEIGHT REDUCTION, ELONGATION, ULTRASONIC TESTS, ELASTIC WAVES, TRANSVERSE, UNIDIRECTIONAL, FIBER REINFORCEMENT, CARBON STEELS.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE