Evaluation of mechanical properties of structural materials by a spherical indentation based on the representative strain-an improved algorithm at great depth ratio

At great depth ratio, two methodologies based on the representative strain were improved to extract mechanical properties of metallic engineering structural materials from P-h curve of an indentation response. The improved aspects include: the combination of great ratio h(1)/R=0.1 and h(2)/R=0.4 replaced h(1)/R=0.01 and h(2)/R=0.06 (Cao's method) and h(1)/R=0.1 and h(2)/R=0.3 (Ogasawara's method); three types of metallic engineering structural materials with obviously different elastic modulus were dealt with to get their calculation parameters, respectively; a new parameter reflecting the effect of work-hardening exponent n was introduced to get the dimensionless function which is independent of n and a relationship between W/(h(3)sigma S-r) and E*/(sigma S-r) at great depth ratio. By using the results of finite element simulation, the efficiency and accuracy of the improved method have been proved, and it showed that the accuracy of the improved method is much better than the former method.