Seminar - Charles K.S. Loo Chin Moy - Identification of multilayer material properties based on the application of an inverse analysis technique

Wednesday 21 October 2009, 1.10 pm - 1.55 pm
Civil Engineering Lecture Theatre 3

Abstract:
Multilayered composites consisting of either metal/metal or metal/ceramic layers are attractive materials because of their proven enhancement in strength, toughness and damage tolerance. For example, current applications utilise nanostructured hard coatings such as CrN, ZrN and TiN onto cutting tools considerably to extend the usage time of a component due to increased wear resistance.

In the case of layered materials the structural response may be affected by the behaviour of a single layer or by the interface properties between layers. For this purpose, standard tests may not always provide all the parameters required for an adequate analysis to be used in design. In these cases, alternative testing methodologies need to be utilised. A very common approach relies on the use of indentation tests even if the post-processing of the results becomes more complex than in the case of the more traditional tensile test and other techniques, such as the inverse analysis one, need to be adopted.

The proposed work focuses on the development of an inverse analysis approach for the characterisation of the material properties of multilayered material systems. This approach makes use of the indentation curve obtained from an instrumented indenter and the mapping of the surface imprint which can be obtained from an Atomic Force Microscope (AFM) or a profilometer. It is capable of identifying the yield stress fy and strain-hardening parameter n of the individual layers. The adequacy of the procedure has been tested for a wide range of material properties based on computer generated experimental data disturbed with different levels of noise.