Bridging stress determination by evaluation of the R-curve

A procedure is proposed which allows for bridging stress determination from a measured R-curve. An application of the method is illustrated for a magnesium aluminate spinel ceramic that exhibits an extended linear R-curve behavior. The analytical determination of small displacement behavior and the treatment for large displacements using cubic splines is outlined in detail. After an initial increase, bridging stress values are found to decrease for larger crack opening displacements.