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|Title:||Modeling size effects in nano-indentation of polymers||Authors:||POH LEONG HIEN||Keywords:||Size effects; Nano-indentation; Glassy polymers; Epoxy; Strain gradient plasticity; Finite element method||Issue Date:||30-Jul-2005||Citation:||POH LEONG HIEN (2005-07-30). Modeling size effects in nano-indentation of polymers. ScholarBank@NUS Repository.||Abstract:||In recent years, material characterization using indentation techniques have gained popularity. It has been reported that when deformations are induced in the submicron level, the materials display strong size effects. Classical plasticity theory is unable to account for this phenomenon and strain gradient plasticity theory is proposed. The present study adopts constitutive models for glassy and epoxy polymers which are then implemented in the finite element package ABAQUS, via user subroutines. It is demonstrated that strain gradient effects has to be considered to better describe the material response of glassy and epoxy polymers at submicron indentations. The study also covers the two approaches of deriving the values of effective strain gradient via indentation geometry and directly from finite element nodal displacement parameters. The latter, as expected, provides slightly more accurate solutions as compared to the test results than the former but at a marginally higher computing time and resources.||URI:||http://scholarbank.nus.edu.sg/handle/10635/14817|
|Appears in Collections:||Master's Theses (Open)|
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