ANALYSIS OF MODULUS AND STRENGTH OF DRY AND WET THERMOSET AND THERMOPLASTIC COMPOSITES LOADED IN TRANSVERSE TENSION

Micromechanical finite element analysis of modulus and strength of tra nsverse tension loaded continuous fiber composites is presented and re lated to experimental data for dry and wet glass/epoxy, carbon/epoxy, glass/polyphenylsulfide (PPS) and carbon/bismaleimide (BMI)-epoxy comp osites. Transverse tensile strength predictions employed the combined mechanical and residual stress states at the fiber/matrix interface an d in the matrix in conjunction with debonding and matrix failure crite ria. Due to lack of experimental data on fiber/matrix interfacial stre ngths, an ideal bond was assumed by assuming that the interfacial tens ile and shear strengths were the same as those for the matrix. The Coo per-Kelly transverse strength model was also examined. Predictions of the transverse Young's modulus using finite elements were overall in g ood agreement with experimental values at dry and wet conditions. The transverse stress levels corresponding to debond initiation and matrix failure generally decreased with increased amounts of absorbed moistu re which is consistent with experimental observations, but due to the ideal fiber/matrix bond assumption, the strength predictions tended to be unconservative. The Cooper-Kelly Model with a weak fiber/matrix in terface yielded highly conservative strength predictions.