Accession Number : ADB053356

Title :   Modelling Microfracture Processes in Fibrous Composites,

Corporate Author : CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF ENGINEERING

Personal Author(s) : Beaumont, P. W. R.

Report Date : 1979

Pagination or Media Count : 70

Abstract : This report derives the expressions used to calculate the strength, cracking stresses and toughness (fracture energy) of simple, unidirectional fibrous composites. We offer some explanation of the fracture mechanisms and the limitation of each model in quantitatively describing the cracking stress and toughness. The equations determined are based on physically sound microscopic models of fracture. Frequently, this leads to an equation containing one or more terms for which only bounds are known or can be found. Theory provides the form of the equation; we then have to resort to experimental data to order to determine the constants which enter it. By determining data for the material properties, these equations can be used to compute model-based fracture diagrams where the contributions of each model of fracture are compared to the measured values of fracture toughness of the composite. While the models for the fractured processes are numerous, it must be emphasized that at present they are crude. In many cases they contain no information about the strain hardening of the fiber and matrix, and nothing about the strain-rate sensitivity of the fiber and matrix.

Descriptors :   *FIBER REINFORCED COMPOSITES, *FRACTURE(MECHANICS), MATRIX MATERIALS, STRENGTH(MECHANICS), CRACKS, STRESS STRAIN RELATIONS, TOUGHNESS, STRAIN HARDENING, SENSITIVITY, STRAIN RATE, MICROSCOPY, MODELS, POLYMERS, METALS, GLASS, CERAMIC MATERIALS, LOADS(FORCES), ELASTIC PROPERTIES, BRITTLENESS, DUCTILITY, DEFORMATION, STRESS RELAXATION, EQUATIONS.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE