ABSTRACT
They concluded that with blunt indenters existing surface flaws dominate the fracture pattern during indentation and deformation induced flaws dominate the fracture pattern with sharp indenters. Chen and Lapua (2006) conducted indentation tests on Berea sandstone and charcoal granite with 4 different indenters and varying confinement and concluded that at low confinement rocks fragments in brittle manner and at high confinement they fragment in a plastic manner thus giving an idea about the effect of insitu stress. Howarth and bridge (1988) conducted indentation tests on Microsyenite and granite with various spacing to penetration ratios. They conducted tests on granites to look for the reproducibility of experiments and found out a low spacing to penetration ratios they are reproducible and at high ratio comparable differences arises. Cook (1984) conducted indentation tests on Sierra granite using circular flat bottomed punches with various diameters to study the effect of punch size and confining pressure. He concluded with punch size indentation strength decreases and at low confining pressure sample splits in two in a plane passing through the axis of the punch.
