The indentation size effect in the spherical indentation of iridium: A study via the conventional theory of mechanism-based strain gradient plasticity
The indentation size effect in the spherical indentation of iridium: A study via the conventional theory of mechanism-based strain gradient plasticity
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DOI：
10.1016/j.ijplas.2005.07.008
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发表时间：
2006-07
影响因子：
9.8
通讯作者：
S. Qu;Yonggang Huang;G. Pharr;K. Hwang
中科院分区：
文献类型：
--
作者：
S. Qu;Yonggang Huang;G. Pharr;K. Hwang
基于Taylor位错模型建立的应变梯度塑性力学理论，研究了球形压痕实验中压痕尺寸效应。本研究采用了两种方法。第一个是约翰逊的[约翰逊，K.L.，1970.压痕实验的相关性。Journal of the Mechanics and Physics of Solids 18，115-126.]基于CMSG的理论压痕模型不能预测铱的实验数据。在第二种方法中，CMSG的有限元方法用于表征压痕材料。压痕硬度的预测值与实验值吻合较好。建立了一个简单的解析压痕模型，给出了压痕硬度H= H 0 2 +141α2μ2bR与球形压头半径R的关系，其中H 0是不考虑压头半径效应的压痕硬度（即，由经典塑性理论给出），μ是剪切模量，B是Burgers矢量的大小，α是泰勒位错模型中约1/3的经验系数。
The indentation size effect in spherical indentation experiments is studied via the conventional theory of mechanism-based strain gradient plasticity (CMSG) established from the Taylor dislocation model. Two approaches are adopted in the present study. The first, an extension of Johnson’s [Johnson, K.L., 1970. The correlation of indentation experiments. Journal of the Mechanics and Physics of Solids 18, 115–126.] theoretical indentation model based on CMSG, fails to predict the experimental data for iridium. The finite element method for CMSG is used to characterize the indented material in the second approach. The predicted indentation hardness agrees well with the experimental data. A simple, analytic indentation model is established to give the indentation hardness H=H02+141α2μ2bR in terms of the radius R of the spherical indenter, where H0is the indentation hardness without accounting for the tip radius effect (i.e., given by classical plasticity theories), μ is the shear modulus, b is the magnitude of the Burgers vector, and α is the empirical coefficient around 1/3 in the Taylor dislocation model.