FRACTURE AND FATIGUE BEHAVIOR OF LATH WITH A CENTER CRACK STRENGTHENED WITH FRP SHEET

Fracture and fatigue of a lath with a center crack strengthened with FRP sheet, subject to tensile loads at its two ends, was investigated, and the interfacial shear stress of the FRP-strengthened lath was obtained. Based on the superposition principle and the fracture mechanics, an analytical expression of the stress intensity factor at crack tip of the FRP-strengthened lath was derived. Then, the formulas of the fatigue life assessment of the FRP-strengthened lath with a center crack were presented with the Paris model and Elber model, respectively. From analysis of a numerical example, it was found that the effect of the crack closure is significant for the FRP-strengthened lath with a center crack under cyclic loading, and the Elber model should be employed to assess its fatigue life, while Paris model should be employed to assess fatigue life of the un-strengthened lath. Furthermore, the parameter study showed that there exists an optimal length of the FRP sheet, and the influence of the FRP stiffness on the amplitude of the stress intensity factor is significant. The amplitude of the stress intensity factor decreases when the FRP stiffness increases, resulting in an increased fatigue life.