Experimental analysis of parameters needed for calculation of fracture toughness using surface cracks generated by Vickers test at different loads

Using surface cracks generated by Vickers test is one of the new and low cost methods for determining the fracture toughness of brittle materials. In this paper، numerical and experimental analysis is performed on the equation related to this new method. The effective of creation of chips، interval of numerical results for determining the surface crack parameters، thickness of micro cracks; elastic-plastic conditions of the specimens in negligible loadings and boundary conditions are discussed. For this research، various composites like as Al2O3-%6NanoSiC، Al2O3 - %12 NanoSiC - %1MgO، Al2O3 - %18NanoSiC - %3MgO، B4C - %8NanoTiB2-%1Ni - %2Fe، B4C - %8NanoTiB2 - %3Ni - %3Fe with different loads are sintered and prepared. This research shows a little difference between the results obtained from the mentioned equation in various loading، different mechanical properties and alternation of mechanism of crack growths. It is also concluded that variation of amount of loading in nano-sizes leads the elastic behavior of the specimens.