Fatigue crack growth in double cantilever beam specimen with an adhesive layer

A test method based on fracture mechanics concepts is applied to measure fatigue crack growth rates for an adhesive material in a bondline double cantilever beam specimen containing a cohesive crack. Tension-tension tests are conducted with a stress ratio of 0.5 and at 5 Hz. Debond growth rates are measured using a compliance method. Corresponding changes in J-integral are computed based on the beam on elastic-plastic foundation analysis of the specimen. There are three bondline thicknesses that are evaluated. When computed, ΔJ are plotted against the measured debond growth rates, the results showing a power law relationship which characterizes the debond behavior for a given bondline thickness. The increase of bond line thickness has a significant effect on fatigue crack growth. The larger the bond line thickness, the larger is the fatigue crack growth resistance.