CMS 9800413 PI: S.L. Phoenix Cornell University ABSTRACT A combined experimental and theoretical study of the creep fracture in unidirectional, graphite fiber/polymer-matrix composite materials in tension is conducted. Creep fracture is important in various applications such as filament wound pressure vessels, pultruded rods and beams, offshore platform stabilizing cables and pipes, all of which sustain high loads for long times. The model incorporates micromechanical and statistical failure processes in the composite, and yields probability distributions for strength and long-term lifetime. Micro-Raman Spectroscopy (MRS) is used to study matrix creep and time-dependent interfacial debond and slip phenomena at length scales closer to fiber diameter. Fast comutational micromechanics model for the composite is developed that provides stress and displacement fields for large random arrays of fiber breaks and break clusters for use in large Monte Carlo simulations. The MRS experiments and computational model are interactively used to interpret experimental stress profiles as they change over time. ***
