Dynamic Modeling of the Polymeric Materials to Measure the Contact Area during Nano-Indentation Tests

• Main Authors: Chang, Hon-Zoon, 張鴻仁
• Other Authors: Ha, Jih-Lian
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/9cxzec

碩士 === 遠東科技大學 === 機械工程研究所在職專班 === 100 === A mechanical model is developed in the present study for polymeric materials in order to evaluate their contact areas varying with the loading/ unloading rate given in nano-indentation tests. Two governing differential equations are derived for the depth solution of the indenter tip and the depth solution formed at the separation point; they are expressed in a power form of the depth parameters. All spring/block coefficients and damping coefficients shown in these two differential equations associated with the elastic/plastic and viscous effects respectively are determined by the real-coded genetic algorithm. In either the loading or unloading process, an asymptotic formula is applied to incorporate the experimental data shown at small and large indentation depths. These two formulae provide the exponent value in the depth parameters to be varied with the indentation depth. Pile-up behavior is included in the evaluation of the contact projected area (A). Differences among the contact area solutions, obtained from four models including the present model, are evaluated in terms of relative error.