The Influence Of Surface Roughness In Micro Indentation

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Date
2013-11
Authors
Chuah, Hun Guan
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Publisher
Universiti Sains Malaysia
Abstract
In micro indentation, scale dependent behavior is encountered as the smaller indentation size produces higher hardness value which is known as indentation size effect (ISE). For small scale indentation, the indent size and the contact asperity size are relatively small if the deformed surface is “rough”. Therefore, the resistance attributed from the friction interface associated with surface roughness alters the deformation severity which contributes to the change of indent size. The effect of surface roughness on ISE in micro indentation is studied using the proportional specimen resistance (PSR) model. With the basis of PSR model, a new normalized hardness model 1 2 1 + + = a d c c R H H o a o is developed to show the relationship between the ISE and the surface roughness. This study shows that the Meyer’s index n increases with rougher surface. From the analysis using the PSR model, rougher surface gives higher proportional specimen resistance due to the increase of coefficient related to proportional specimen resistance a1. Subsequently, the normalized hardness value increases with roughness. In addition, a surface roughness dependent friction model 2 2 2 * 2 0 ) 2.46 0.39 ) ( 2.46 (1 p p h R R h R h H c a a c c o α μ −         − + − + = is developed to predict friction coefficient and the model shows that the rougher surface gives higher value of friction coefficient in micro indentation.
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Keywords
Surface Roughness , Micro Indentation
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