Bridging stress relation from a combined evaluation of the R-curve and post-fracture tensile tests

摘要

Although the R-curve has provided a convenient description of the crack growth resistance behavior for ceramic materials, its shape depends not only on intrinsic material properties, but also on the selected specimen geometry. Therefore, it is of general interest to isolate the geometry-independent material-specific effects. In the case of alumina, bridging stresses in the wake of a crack are responsible for the observed R-curve. In the present study, a procedure is demonstrated which enables one to determine the bridging stress relation from the initial part of the R-curve and post-fracture tensile (PFT) tests. Based on the bridging stresses, the complete R-curve, including large crack extensions, can be computed. The calculated R-curve agrees very well with experimental results.