Table reveals that the elastic modulus E

3.3. Hertzian contact damage mechanisms
Optical half-surface and side views of Hertzian contact damage on material B and C BQ-123 reported in Fig. 2 after indentation with a sphere of radius 1 mm at peak load P =500 N. Material B with 3% of porosity showed deep circular ring cracking which extends into cone cracks propagating downwards. Some damage was also observed below the contact site. For the material with 18% porosity, a clear depression was observed without any evident fracture at the surface. A significant deformation of half hemispherical shape extends beneath the indent. It can be also observed a base pronounced crack at the boundary between the damaged area and the undamaged one ( Fig. 2).
Fig. 2. Optical and laser views of Hertzian damage in material C (i) and B (ii) showing surface (top), subsurface (bottom) from bonded-interface specimen after indentation with 1 mm radius sphere at load P =500 N.Figure optionsDownload full-size imageDownload as PowerPoint slide