Is it possible to measure the tensile strength and fracture toughness simultaneously using flattened Brazilian disk?

The Flattened Brazilian Disk test was designed for measuring both the tensile strength and fracture toughness of rocks. Using cohesive zone modelling, we found that method is practically not suitable extracting toughness, while it works well in calibrating strength. flattened disk provides a very narrow window variation load during failure, <15%, insufficient to reflect change among different materials. crack propagation throughout failure highly unstable dynamic, where linear elastic mechanics applicable. These findings were supported by experimental data. In contrast, Semi-Circular Bend test, with pre-crack, can properly measure but cannot capture general, un-cracked specimens are pre-cracked toughness. It challenging, if impossible, single test. further implied first peak on loading curve such kind tests trustworthy mechanical properties, following second turning point (if existing) unreliable as may contain dynamic effect. results provide useful reference selection design methods using related geometries.