3.4. Method to predict material properties from the Vickers and spherical indentation
3.4.1. Curvature of the indentation curve
As shown in Figures 3.3-5, the P-h curves for both Vickers and Spherical indentation obtained the following relationship:
C = P ℎ
I
⁄ 3.5
Where P and are the load and indentation depth on the loading curve respectively. C is the curvature coefficient with the curvature for the Vickers Indentation and spherical
indenter designated as ‡
¦
and ‡
§
respectively. The curvature is a function of the yields stress and the work hardening coefficient. This will provide a relationship which potential
allow the prediction of material parameters from continuous indentation tests. Figure 3.6 is a flow chart showing the main structure of the inverse modelling approach to
predict the material properties. In the first stage, systemic FE models were developed to form he simulation space covers the potential range of material properties. In the next
stage, the loading curves were used to develop an simulation space. The data will then be processed through three different approaches 3D mapping, dimensional analyse, and dual
indenter chart approach to predict the material parameters. Details of each approach and the results were presented in the next sections with discussion.
The three approaches have been comparative developed to assess their suitability to predict the materials properties based on the dual indenter approach. The second approach
is normalised dimensionless analysis in which the relationship is normalised than a dimensionless analysis is applied. In the third approach, the relationship between the
curvature for both the Vickers and spherical were developed then used a chart to predict all the material sets with the same curvature. The relationship is used to predict the
material sets have the sane indentation curvature. The key procedures of each approach and the typical results are detailed in the next three sections.
3.4.2. 3D- Mapping approach
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