Accession Number : ADA330185

Title :   Rate Dependent Cohesive Zones

Descriptive Note : Final rept. 15 Apr 94-14 Sep 97

Corporate Author : ROCKWELL INTERNATIONAL CORP THOUSAND OAKS CA SCIENCE CENTER

Personal Author(s) : Cox, B. N.

PDF Url : ADA330185

Report Date : SEP 1997

Pagination or Media Count : 105

Abstract : In work under another contract, we had studied the initiation of mode I tensile cracks (not delamination cracks) that tunnel down individual plies in brittle matrix laminates or woven textiles and then turn into plane cracks spreading across many plies en route to part failure. Under this contract, we unified this modeling with our models of cracks bridged by creeping fibers. In the absence of fiber creep, the plane strain phase of crack propagation often (and desirably) ends in crack arrest, because the plane strain crack grows into a lengthening bridging zone as the crack traverses plies. However, fiber creep relaxes the bridging and allows crack growth to resume, which leads to failure at undesirable low stresses. We developed comprehensive solutions to this mode of crack growth.

Descriptors :   *CRACK PROPAGATION, *COHESION, TENSILE STRESS, CERAMIC MATRIX COMPOSITES, COMPOSITE STRUCTURES, FRACTURE(MECHANICS), THREE DIMENSIONAL, CREEP, FATIGUE(MECHANICS), MICROMECHANICS, DELAMINATION, BRIDGES.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE