Analysis of instrumented indentation test data for functionally graded materials

The present work is concerned with methods of analysis of data obtained from instrumented depth-sensing nanoindentation testing performed on materials whose elastic modulus varies with depth from the specimen surface. Conventional methods of analysis assume that the elastic modulus of the specimen material is a constant. The present work shows that presently existing analytical models for functionally graded materials are not suitable for use with conventional nanoindentation analysis methods. The finite element method is used to show that depth-profiling of mechanical properties using conventional analysis techniques leads to discrepancies in the values of computed modulus and hardness compared to the actual values of these properties.