The title problem was investigated experimentally and numerically. Aluminum adherends and two adhesives, AF-55 and AF-127, were utilized in the investigation. Each specimen had a crack introduced at an undoubled edge. Fatigue cycles with a fixed average remote-stress maximum of 103.4 MPa at a stress ratio of 0.1 were applied to grow the initial crack up to and beneath the doubler. Crack-growth rates were measured to assess the inhibiting effect of the doubler, and ultrasonic scans were made to determine debond-zone shapes. After each crack had grown approximately halfway beneath the doubler, a secondary crack initiated at the edge of the doubler, precipitating rupture of the specimen. A finite-element model of the specimen employed a singularity element to represent the crack-tip neighborhood and shear springs to represent the adhesive layer. Springs were released in the model to simulate local debonding. The stress-intensity factor was computed as a function of crack length for linear and nonlinear representations of the two adhesives used in the experimental program.

This content is only available via PDF.
You do not currently have access to this content.