On the uniqueness of measuring elastoplastic properties from indentation: The indistinguishable mystical materials
On the uniqueness of measuring elastoplastic properties from indentation: The indistinguishable mystical materials
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DOI：
10.1016/j.jmps.2007.01.010
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发表时间：
2007-08-01
影响因子：
5.3
通讯作者：
Chiba, Norimasa
中科院分区：
文献类型：
--
作者：
Chen, Xi;Ogasawara, Nagahisa;Chiba, Norimasa
压痕法被广泛用于从测得的力-位移曲线中提取材料的弹塑性特性。最成熟的压痕技术之一是利用双（或多个）尖锐压头（具有不同的顶角）来推导关键参数，如弹性模量，屈服应力和加工硬化指数的材料，服从幂律本构关系。然而，这种分析的独特性尚未得到系统的研究或质疑。在这里，我们显示了“神秘材料”的存在，它们具有独特的弹塑性特性，但它们产生几乎相同的压痕行为，即使当压头角度在很大范围内变化。这些神秘的材料，因此，许多现有的压痕分析无法区分，除非极端（往往是不切实际的）压头角度使用。建立了推导这些神秘材料的明确程序，并讨论了神秘材料的一般特征。在许多情况下，对于一个给定的压头角度范围内，一种材料将有无限多的神秘兄弟，神秘材料的存在地图也得到了。此外，我们提出了两种替代技术，以有效地区分这些神秘的材料。本文的研究解决了压痕试验唯一性这一重要问题，为正确使用压痕技术测量材料的弹塑性性能提供了有益的指导。(C)2007爱思唯尔有限公司保留所有权利。
Indentation is widely used to extract material elastoplastic properties from the measured force displacement curves. One of the most well-established indentation techniques utilizes dual (or plural) sharp indenters (which have different apex angles) to deduce key parameters such as the elastic modulus, yield stress, and work-hardening exponent for materials that obey the power-law constitutive relationship. However, the uniqueness of such analysis is not yet systematically studied or challenged. Here we show the existence of "mystical materials", which have distinct elastoplastic properties yet they yield almost identical indentation behaviors, even when the indenter angle is varied in a large range. These mystical materials are, therefore, indistinguishable by many existing indentation analyses unless extreme (and often impractical) indenter angles are used. Explicit procedures of deriving these mystical materials are established, and the general characteristics of the mystical materials are discussed. In many cases, for a given indenter angle range, a material would have infinite numbers of mystical siblings, and the existence maps of the mystical materials are also obtained. Furthermore, we propose two alternative techniques to effectively distinguish these mystical materials. The study in this paper addresses the important question of the uniqueness of indentation test, as well as providing useful guidelines to properly use the indentation technique to measure material elastoplastic properties. (C) 2007 Elsevier Ltd. All rights reserved.