Solvent stress cracking and failure mechanisms in polyetherimide composites

Abstract Solvent stress cracking studies have been carried out in o‐xylene and other solvents on polyetherimide (PEI) based materials including neat resin, woven fabric composites, and adhesively bonded systems. The results show crack growth in solvents at very low G _I levels as compared with tests in air. The composite and adhesively bonded systems have sufficiently high residual thermal stresses to drive an array of intersecting matrix/adhesive cracks even without mechanical loading. The matrix/adhesive residual stress driven crack patterns in these systems are shown to retard main delamination crack growth relative to that in the neat resin, and to raise the applied threshold G ₁ level for main crack growth by about a factor of ten, as predicted by an approximate model.