Partitioning of mixed-mode fracture in adhesively-bonded joints: experimental studies

The fracture resistance, Gc, of adhesively bonded joints is known to vary significantly with loading mode and because joints are usually subject to mixed-mode loading in service, it is essential to be able to partition Gc into its I/II components so the appropriate failure criterion can be derived. Various partitioning schemes have been proposed in the literature but they give different results and which is most suitable has been an open question. In this work, joints were tested under a wide range of I/II loading ratios and the various partition schemes were assessed. The singular and global schemes were found to define the extremes, while Davidson’s non-singular field scheme represents an intermediate case. The semi-analytical scheme proposed by Conroy et al. exhibited a gradual transition from the singular to the global solutions and was shown to be the best approach