Fatigue performance of FRP sandwich panels

This paper describes the fatigue performance of GFRP sandwich panels designed to resist highway traffic loading. Sandwich core structures are introduced and discussed. The design basis for roadway plates and access covers are discussed, and a testing protocol that is intended to demonstrate static, sustained load, and fatigue performance is outlined. The fatigue testing of panels under various fatigue amplitudes is presented. Observed failure modes are attributed to the core structure, skin construction, or the core-skin interface. Service life under fatigue loading is related to traffic spectra taken from weigh-in-motion data. Data from load cycling at 54 kN and 74 kN indicate that the panels will have a long service life in most traffic conditions. The end of the service life is evidenced by the gradual loss of stiffness under constant load amplitude fatigue loading. Panels whose fatigue load is approximately 30% of their static strength appear to demonstrate an infinite fatigue life.