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

Although the R-curve has provided a convenient description of the crack gro wth resistance behavior for ceramic materials, its shape depends not only o n 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 s tudy, a procedure is demonstrated which enables one to determine the bridgi ng stress relation from the initial part of the R-curve and post-fracture t ensile (PFT) tests. Based on the bridging stresses, the complete R-curve, i ncluding large crack extensions, can be computed. The calculated R-curve ag rees very well with experimental results.