Compliance Methods For Bonded Joints: Part II - Investigation Of The Equivalent Crack Methodology To Obtain The Strain Energy Release Rate For Mode I

ABSTRACT The present work investigates the equivalent crack methodology by considering the Double Cantilever Beam (DCB) test to obtain the strain energy release rate of adhesive joints, using different compliance methods rather than the Compliance Based Beam Model (CBBM). This procedure allows the determination of the crack length based on the compliance of the specimen, which avoids crack growth monitoring during tests. The compliance values predicted by the analytical methods were studied and compared with a computational model, considering different crack lengths. Results showed that the preciseness of the crack length obtained by the equivalent crack method relies on the accuracy of the respective compliance method in predicting the load-displacement curve of a bonded double cantilever beam. The Euler–Bernoulli and Timoshenko beam models are not recommended to obtain an equivalent crack length based on the specimen’s compliance since they overestimate the actual crack length. Best crack length predictions were obtained using compliance methods based on the beam-on-elastic foundation models, including an elastic interface to model the adhesive layer joint. Similar strain energy release rate results were found for different compliance methods when using the equivalent crack methodology.