A PARAMETRIC STUDY OF VARIABLES THAT AFFECT FIBER MICROBUCKLING INITIATION IN COMPOSITE LAMINATES .1. ANALYSES

The objectives of this research focus on the effects of nonlinear matrix constitutive behavior, initial fiber waviness, and fiber/matrix interfacial bond strength on fiber microbuckling initiation in thermoplastic composites. Nonlinear geometric and nonlinear material two-dimensional finite element analysis is used to model the initiation of fiber microbuckling of an initially wavy fiber. Results show that reductions in the resin shear tangent modulus, larger amplitudes of initial fiber wavinesses, and debonds each cause increases in the localized matrix shear strains; these increases lead to premature fiber microbuckling initiation. These numerical results are compared with experimental data obtained during this investigation. These experimental results and comparisons are presented in a companion paper [1].