Nondestructive evaluation of material strength using depth-sensing indentation

Successful application of any structural repair or strengthening method requires knowledge of strength and stiffness properties of the materials used in the construction. Depth-sensing indentation is a relatively new material testing method that significantly expands the capabilities of conventional hardness tests. Due to the mathematical complexity of the indentation problem, an analytical solution of the load–penetration depth ( P – h ) behavior is not available for most indenters. This study derives the P – h equations for a truncated cone indenter with arbitrary tip radius and included angle, which covers a wide range of geometries including the cylinder and the cone. A step by step procedure for material strength evaluation is introduced and validated using recorded indentation data. The analytical approach described in this paper can be used in evaluating the modulus of elasticity, stiffness and hardness of common construction materials without resorting to empirical equations.