Estimation of deformation and fracture parameters through the inverse analysis of nanoindentation behavior

本研究的目的是通过计算机模拟和反分析相结合的方法，从纳米压痕行为中提取反映局部变形和断裂的力学性能。新的方法来估计机械性能既不依赖于接触力学，也不依赖于力学模型。在本计画的第一年，借由奈米压痕行为的反分析，可以精确地估计弹塑性体的杨氏模量、泊松比、屈服应力与应变硬化系数。在该项目的第二年，对薄膜/基底系统进行逆分析，以推导薄膜的力学性能。在弹性膜/弹性基底系统的情况下，膜的杨氏模量被成功地估计。弹塑性薄膜/弹塑性基底的反分析正在进行研究。粘弹性体的分析也计划进行调查。研究了电子管金属等离子体电解氧化（PEO）在金属基体上制备陶瓷膜的工艺。在第一年中，发现用含有α-Al_2 O_3的PEO在铝上制备的氧化膜显示出与烧结氧化铝多晶相当的高硬度。第二年，对钛进行PEO处理，在其上产生钛氧化物，可以控制氧化膜的结晶和微观结构发展。不仅机械性能，而且光催化性能的氧化膜进行了检查。用Poole-Frenkel效应的电子雪崩理论解释了PEO处理产生氧化膜的机理。

The aim of this study is to extract mechanical properties, which reflects local deformation and fracture, from nanoindentation behavior through the combination of computer simulation and inverse analysis. The novel method to estimate mechanical properties depends on neither the contact mechanics nor mechanical models. In the first year of this project, the Young's modulus, Poisson's ratio, yield stress and strain hardening coefficient of an elastoplastic body can be estimated precisely through the inverse analysis of nanoindentation behavior. In the second year of this project, the inverse analysis is applied for film/substrate systems to derive the mechanical properties of the film. The Young's modulus of a film is successfully estimated in the case of elastic film/elastic substrate systems. Inverse analysis of elastoplastic film/elastoplastic substrate is going on studying. The analysis of viscoelastic bodies is also planned to investigate. Plasma electrolic oxidation (PEO) of valve metals to create ceramic films on metal substrate is studied. It is, in the first year, found that Oxide film on aluminum fabricated with PEO, which contains a-Al2O3, shows high hardness that is equivalent with that of sintered alumina polycrystals. In the second year, PEO treatment is applied for titanium to create titanium oxide on it, and the crystallization and microstructual development of the oxide film can be controlled. Not only mechanical but also photocatalytic performance is examined on the oxide film. The mechanism to produce oxide films with PEO treatment is found to be explained through electronic avalanche theory with Poole-Frenkel effect.