FATIGUE-CRACK GROWTH IN DOUBLE CANTILEVER BEAM SPECIMEN WITH AN ADHESIVE LAYER

A test method based on fracture mechanics concepts is applied to measu re fatigue crack growth rates for an adhesive material in a bondline d ouble cantilever beam specimen containing a cohesive crack. Tension-te nsion tests are conducted with a stress ratio of 0.5 and at 5 Hz. Debo nd growth rates are measured using a compliance method. Corresponding changes in J-integral are computed based on the beam on elastic-plasti c foundation analysis of the specimen. There are three bondline thickn esses that are evaluated. When computed, Delta J are plotted against t he measured debond growth rates, the results showing a power law relat ionship which characterizes the debond behavior for a given bondline t hickness. The increase of bond line thickness has a significant effect on fatigue crack growth. The larger the bond line thickness, the larg er is the fatigue crack growth resistance. (C) 1998 Elsevier Science L td. All rights reserved.