Abstract
Reliable viscoelastic coefficients of matrix resin over ranges of time are indispensable for reliable long-term life prediction of carbon fiber reinforced plastics (CFRPs) and their structures. A new methodology is proposed herein for finding the master curve of the reliable long-term relaxation modulus of matrix resin by combining frequency-dependent and temperature-dependent storage moduli measured using a dynamic mechanical analyzer (DMA) and time-dependent and temperature-dependent creep compliance measured using a creep testing machine. First, the new methodology is introduced based on the linear viscoelastic theory. Second, two viscoelasticity testing methods using DMA tests and creep tests are explained. Third, the short-term storage moduli by DMA and the long-term creep compliances by creep testing machine are measured at various temperatures for a heat-resistant epoxy resin. Fourth, the relaxation moduli for a wide range of time and at various temperatures are constructed using the data measured from DMA and creep testing machine. Finally, based on the modified time-temperature superposition principle, a master curve of the relaxation modulus is obtainable for an extremely wide range of time at a reference temperature.
