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ANALYSIS ON PSEUDO-STEADY INDENTATION CREEP
作者单位:Division of Applied Physics,College of Engineering,Nihon University,Fukushima,Japan
摘    要:Theoretical analysis and finite element (FE) simulation have been carried out for a constant specific load rate (CSLR) indentation creep test. Analytical results indicate that both the representative stress and the indentation strain rate become constant after a transient period. Moreover, the FE simulation reveals that both the contours of equivalent stress and equivalent plastic strain rate underneath the indenter evolve with geometrical self-similarity. This suggests that pseudo-steady indentation creep occurs in the region beneath the indenter. The representative points in the region are defined as the ones with the equivalent stress equal to the representative stress. In addition, it is revealed that the proportionality between indentation strain rate and equivalent plastic strain rate holds at the representative points during the pseudo-steady indentation creep of a power law material. A control volume (CV) beneath the indenter, which governs the indenter velocity, is identified. The size of the CV at the indented surface is approximately 2.5 times the size of the impression. The stress exponent for creep can be obtained from the pseudosteady indentation creep data. These results demonstrate that the CSLR testing technique can be used to evaluate creep parameters with the same accuracy as conventional uniaxial creep tests.

关 键 词:压痕蠕变  有限元方法  中心锥体  控制体积  应力指数
收稿时间:24 June 2008

ANALYSIS ON PSEUDO-STEADY INDENTATION CREEP
Authors:Hidenari Takagi  Ming Dao  Masami Fujiwara
Institution:[1]Division of Applied Physics, College of Engineering, Nihon University, Fukushima, Japan [2]Department of Materials Science and Engineering, School of Engineering, Massachusetts Institute of Technology, Massachusetts, USA
Abstract:Theoretical analysis and finite element(FE)simulation have been carried out for a constant specific load rate(CSLR)indentation creep test.Analytical results indicate that both the representative stress and the indentation strain rate become constant after a transient period. Moreover,the FE simulation reveals that both the contours of equivalent stress and equivalent plastic strain rate underneath the indenter evolve with geometrical self-similarity.This suggests that pseudo-steady indentation creep occurs in the region beneath the indenter.The representative points in the region are defined as the ones with the equivalent stress equal to the representative stress.In addition,it is revealed that the proportionality between indentation strain rate and equivalent plastic strain rate holds at the representative points during the pseudo-steady inden- tation creep of a power law material.A control volume(CV)beneath the indenter,which governs the indenter velocity,is identified.The size of the CV at the indented surface is approximately 2.5 times the size of the impression.The stress exponent for creep can be obtained from the pseudo- steady indentation creep data.These results demonstrate that the CSLR testing technique can be used to evaluate creep parameters with the same accuracy as conventional uniaxial creep tests.
Keywords:indentation creep  finite element method  conical indenter  geometrical self-similarity  pseudo-steady state  control volume  stress exponent
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