Accession Number : ADA305263

Title :   Analysis of the Effect of Matrix Degradation on Fatigue Behavior of a Graphite/Epoxy Laminate.

Descriptive Note : Master's thesis,

Corporate Author : TEXAS A AND M UNIV COLLEGE STATION MECHANICS AND MATERIALS CENTER

Personal Author(s) : Arenburg, Robert T.

PDF Url : ADA305263

Report Date : MAY 1982

Pagination or Media Count : 122

Abstract : An analytical study of the effect of fatigue on a + OR - 45/90 SUB 2sub s graphite/epoxy laminate is conducted considering two levels of damage. The first one is microscopic damage, which is viewed as a matrix softening mechanism that is accounted for by the use of micromechanics. The second level of damage is delamination. An evaluation of lamination theory versus a finite element elasticity solution which accounts for free edge stresses is made first. Lamination theory is found to be inadequate due to its inability to account for large amounts of shear deformation as the matrix degrades. Experimental data are used to evaluate the matrix degradation as a function of fatigue cycles, and then a parametric study of the strain energy release rate as a function of delamination size at various degrees of matrix degradation is conducted. For a constant maximum stress fatigue test, the matrix degradation leads to an increase in strain energy which is predicted to eventually cause rapid delamination. Reasonably good agreement between theory and experimental data on the + OR - 45/9O sub 2sub s laminate is demonstrated. (MM)

Descriptors :   *FIBER REINFORCED COMPOSITES, *EPOXY LAMINATES, *FATIGUE(MECHANICS), *GRAPHITE EPOXY COMPOSITES, DAMAGE, DEGRADATION, FINITE ELEMENT ANALYSIS, DEFORMATION, STIFFNESS, CRACKING(FRACTURING), DISPLACEMENT, ELASTIC PROPERTIES, THESES, MATRIX MATERIALS, ENERGY TRANSFER, STRAIN RATE, HELICOPTERS, MICROMECHANICS, DELAMINATION, ROTOR BLADES.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE