SIMULATION OF BERKOVICH NANOINDENTATION EXPERIMENTS ON THIN-FILMS USING FINITE-ELEMENT METHOD

The Finite element technique is applied for studying the very complex stress-strain field of thin hard coatings subjected to a. nanoindentat ion process. Berkovich indentation experiments were simulated with the ABAQUS finite element software package. The investigated system was t itanium nitride on high speed steel as an example of a hard film on a softer substrate. The numerical analysis allowed the plastic deformati on history during indentation to be followed. In particular, it was po ssible to correlate the onset of plastic deformation in the substrate with the shape of the loading curve. The system was simulated by an ax isymmetric model in which the conical indenter has the same contact ar ea as the Berkovich indenter. A six-fold symmetric three-dimensional m odel was also defined for testing the suitability of the previous mode l. The indenter was modeled either as a ri,aid surface or as a deforma ble diamond tip. Comparison between the experimental data and numerica l results demonstrated that the finite element approach is capable of reproducing the loading-unloading behavior of a nanoindentation test. The film hardness of TiN/HSS specimens was numerically calculated for different indentation depths, It was shown that the presence of the su bstrate affected the hardness measurement for relative indentation dep ths greater than about 15% of the film thickness, (C) 1998 Elsevier Sc ience S.A.