Experimental investigation and numerical modeling of creep response of glass fiber reinforced polymer composites

Predictive models play an important role for increasing the reliability of composite structures over time, but a great deal of experimental data is requested. In this paper, results from creep experiments on uniaxial E-glass fiber reinforced polymer (FRP) single ply laminates, performed at different stress levels, are presented. The tests duration was of 42 months. Analytical modeling of the viscous behavior of the tested GFRP composite, under linear and nonlinear viscoelastic hypotheses, is reported. A discussion on the comparison of creep strain response by Burgers model, with parameters obtained from fitting of data for different test duration, is also proposed. Finally, predictive finite element method (FEM) simulations were carried out for discussing the deferred behavior induced by creep, for composite layers used for repair purposes in hydrogen transportation pipes. Numerical results highlighted a non-negligible difference in creep strain values, pointing out that a model based on experimental tests with shorter duration leads to a conservative composite design.