Fatigue crack growth in bonded DCB specimens

Fatigue crack growth tests were conducted on double cantilever beam bonded specimens with the aim to characterize an adhesive for structural applications. The tests were conducted in lab air at two different load ratios, R=Pmin/Pmax, and at two different loading frequencies, f. Crack propagation was monitored using the unloading compliance method. The da/dN vs. ΔG experimental showed the typical sigmoidal shape of bulk materials. Crack closure considerations were successfully used to explain the R-ratio effect. The role of loading frequency was also addressed.