Study of Load Ratio for Mode-I Fatigue Fracture of Wood-FRP-Bonded Interfaces

Abstract

This paper presents the fatigue behavior of interface bond between red maple wood and phenolic FRP substrates. Using linear elastic fracture mechanics concepts, the influence of load ratio on fatigue crack propagation rate is studied. A contoured double cantilever beam (CDCB) specimen is adopted in this study in order to obtain constant strain energy release rate independent of crack length. The compliance method is used for measuring the crack growth rate. A modified Paris Law equation based on strain energy release rate range, ΔG, and mean value of strain energy release rate, G_mean, is proposed in this study for efficient evaluation of load ratio effect on fatigue crack propagation of the bonded interfaces. Follow-up environmental effects are being examined by means of the same energy parameters of the present study and without the need to consider crack closure. The proposed approach can further be extended to characterization of other bonded interfaces for dissimilar materials.

Keywords

contoured double cantilever beam (CDCB) specimen crack propagation rate da/dN load ratio R crack opening displacement (COD)strain energy release rate

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