Finite element analysis on interfacial stress of scratch test

Abstract

The interfacial stress state was evaluated using three dimensional finite element analysis. DLC-Si and TIN were employed as film materials. As a substrate material, heat treated martensitic SUS440 was used. The indenter made of diamond was supposed as a rigid body. The calculated result was in good accordance with actual scratch test on the geometry of scratched groove. From the result of interfacial stress states, the interfacial normal and shear stresses took maximal values at just inside the edge of the groove where the delamination may first occur in actual tests. Moreover, the region where the interfacial shear stress took maximal value was more inside than the interfacial normal stress. Then, the influence of materials properties of the film on the interfacial stress state was discussed by using this finite element model. The interfacial shear stress was more sensitive for the material properties of film than the interfacial normal stress. Finally, the effect of friction at the surface between the indenter and film on the interfacial stress state was discussed. From the result, the interfacial stress was highly influenced by the change of frictional condition on the scratched surface. Therefore, the critical indentation load will fluctuate unless the friction condition was properly controlled. © 2011 IBF (RWTH Aachen) & IUL (TU Dortmund).