No abstract

In this work, finite element (FE) model of spherical indentation has been developed and validated. The relationships between constitutive materials parameters (σy and n) of elastic-plastic materials, indentation P-h curves and hardness on spherical indenters has been systematically investigated by combining representative stress analysis and FE modelling using steel as a typical model material group. Parametric FE models of spherical indentation have been developed. Two new approaches to characterise the P-h curves of spherical indentation have been developed and evaluated. Both approaches were proven to be adequate and effective in predicting indentation P-h curves. The concept and methodology developed is to be used to predict Rockwell hardness value of materials through direct analysis and validated with experimental data on selected sample of steels. The Hardness predicted are compared with the experimental data and showed a good agreement. The approaches established was successfully used to produce hardness values of a wide range of material properties, which is then used to establish the relationship between the hardness values with representative stress.

The indentation size effect (ISE) in Vickers test using steel as a typical model material group with selected heat treatments (annealed or tempered) has been investigated and analysed. Systematically hardness test were performed within a commonly used micro-load range. The ISE data was analysed by fitting data following the Meyer power law and the proportional specimen resistance (PSR) models and the link between ISE and the hardness-to-modulus ratio (H/E) was discussed. The results show that the ISE data correlated well with the Meyers power law (P= A.dn) and the PSR (P/d=a1+a2d) models. The ISE power law index n exhibited a reasonable agreement with the hardness-elastic modulus ratio (H/E), which potentially could be used the relative contributions of plastic and elastic deformation contact area under indentation load and as a measurable input for inverse material parameter prediction.

In this work, the indentation size effect (ISE) in Vickers hardness tests of steel with selected heat treatments (annealed or tempered) has been investigated and analysed. Systematical hardness tests were performed within a commonly used micro-load range. The experimental data was analysed according to the Meyer power-law and the proportional specimen resistance (PSR) models and the link between ISE and material properties was discussed. The results showed that the experimental data fitted well with the Mayers power-law (P = A.dn) and the PSR (P/d = al + a2d) models. The ISE index (n) showed a good correlation with the hardness-elastic modulus ratio (H/E), which potentially could be used to predict the relative contributions of the elastic and plastic deformation contact area under indentation load and to normalize the hardness values for inverse material properties .

Since Asbestos has been banned, the research and development of new gasket materials and designs have continued. One of the materials that are closest to the nature of asbestos is metal. Metal gaskets have been used extensively as static insulation in many industries because they have high temperature and chemical resistance, can withstand pressure, be recycled, and reliability in critical situations. Types of metal gaskets can be distinguished based on their shape. The focus of this research is the corrugated type gasket. Based on previous research, it has been found that important parameters of metal gasket performance are contact width and contact stress. Research developed so far is that the design of corrugated metal gaskets is divided into two types based only on the contact width of the plastic conditions without considering the magnitude of the contact stress and vice versa. In this study, we propose a new approach with contact width and contact stress calculated together as evaluation criteria to optimize corrugated metal gaskets' design. The Taguchi method is used as an optimization design method and a finite element software to obtain result data. This study aimed to obtain an optimal gasket design by utilizing this new approach by using the Taguchi method as an experimental design and simulation method to obtain the result data. This will result in a new design of corrugated metal gasket type which can prevent better leakage performance.