hello,

not really sure if that could be a right way to measure toughness. However  Impact toughness and fracture toughness are measured by destructive testing of unnotched and notch specimens respectively, also known as charpy V or charpy u testing

Hello Bhasker,

Indentation methods of fracture toughness evaluation are well established for brittle materials. Mr. Balaji has provided you some of the references. Your question is about whether it can be extended to metallic materials (I read it as "ductile materials"). It appears so, the topic is still on research and yet to established  as an "accepted"  method for fracture toughness evaluation of ductile materials. The technique is called "automated ball indentation (ABI)" , an idea first promoted by F.M.Haggag (for predicting mechanical properties such as YS,UTS) which was later-on explored by others (including our lab) to predict the fracture toughness of materials (KIC). This is rather a macro method, in which the indentation is repeatedly made at the same location several times, at varying depths at each time. The load and depth of penetration can then be used to evaluate the properties. Look for lit with key words such as, ABI, automated ball indentation, mechanical properties and fracture toughness.

BYW, we have developed and marketing a portable model of ABI that can be taken to the site to measure the mechanical properties on components (including fracture toughness) directly. Sufficient FEM, mathematical formulation, experimental validation and engineering effort has been put behind this development.