MECHANICAL-BEHAVIOR OF + -55-DEGREES FILAMENT-WOUND GLASS-FIBRE/EPOXY-RESIN TUBES .2. MICROMECHANICAL MODEL OF DAMAGE INITIATION AND THE COMPETITION BETWEEN DIFFERENT MECHANISMS/

This series of papers on +/-55 degrees filament-wound glass-fibre/epox y-resin tubes consists of three parts. lit the present paper (Part II) , micromechanical modelling of the damage initiation is conducted in o rder to determine (I) the mechanical conditions under which different microcracking mechanisms occur and (2) the critical sigma(zz)/sigma(th eta theta) ratios which correspond to the change from interfacial fail ure to microcracking at porosity. Emphasis is placed on assessing the influence of microstructural defects and the competition between the d ifferent mechanisms. The general tendency of damage-envelope predictio n by means of micromechanical modelling fits the microscopy observatio ns quite well. The sensitivity of local criteria is also discussed. Th e correction of the local stress field has been improved by introducin g a local stress concentration factor in a mean field theory model (Mo ri-Tanaka theory). In Part I, the microstructural analyses, mechanical behaviour and damage initiation mechanisms were presented. In Part II I, the macroscopic behaviour of the tubing structure with and without damage will be presented The simulation results will be compared with experimental ones. (C) 1997 Elsevier Science Limited.