Indenter surface area and hardness determination by means of a FEM-supported simulation of nanoindentation

摘要

Stress-strain curves are obtained through a finite element method (FEM) simulation of nanoindentation, and the actual indenter tip geometry is determined by additional experimental and FEM-based procedures. Based on such material stress-strain laws and on the actual indenter tip geometry, the following are determined employing the "HANI" algorithm (HArdness determination by means of a FEM-based simulation of Nanoindentation): first, the contact surface due to elastic and plastic deformations during the loading phase of nanoindentation; second the occurring impression geometry after unloading and finally the related hardness values after Martens, Vickers, etc. Moreover, the indenter surface area functions of Vickers and Berkovich indenters are determined experimentally/analytically, by nanoindentations on Si(100) reference material of known Martens hardness. Applying these functions, Martens and Vickers hardness are determined correspondingly for various materials and they are compared to hardness values obtained by the "HANI" algorithm. Significant deviations occur, if the hardness of the reference material is quite different than the hardness of the test pieces.