DETERMINATION OF MECHANICAL PROPERTIES OF THIN FILMS AND FUNCTIONAL GRADIENT MATERIALS USING INVERSE TECHNIQUE
DETERMINATION OF MECHANICAL PROPERTIES OF THIN FILMS AND FUNCTIONAL GRADIENT MATERIALS USING INVERSE TECHNIQUE
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使用逆向技术测定薄膜和功能梯度材料的机械性能
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发表时间：
1999
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影响因子：
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通讯作者：
H. Koguchi
中科院分区：
文献类型：
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作者：
H. Koguchi
本文介绍了一种方法，用于评估材料性能的多层系统和功能梯度材料使用压痕试验获得的数据。通过试验中的穿透力-深度曲线采集的测量数据用于识别薄膜和功能梯度材料的弹性模量。本文首先用三维轴对称弹性理论分析了压痕问题。分析了弹性轴对称压头与多层体系及梯度功能材料的弹性接触问题。在假设基底和压头的弹性模量以及层厚度已知的情况下，进行了确定接触区域的杨氏模量、泊松比和半径的逆分析。当复合形法用于最小化由误差组成的目标函数时，提出了将具有不同曲率半径的压头穿透到涂层基底和功能梯度材料中所获得的数据的有效采样。现代电子设备和大容量存储设备经常具有多层结构，以实现高性能和功能。此外，此类装置通常涂覆有金属薄膜，以防止外部灰尘和环境的损害。对其力学性能进行评估，对于提高设备和机器的可靠性具有重要意义.通常，沉积在衬底上的薄膜的机械性质不同于块体的机械性质。因此，我们需要知道原位沉积膜的机械性能。然而，很难进行用于评估亚微米厚度的膜的机械性能的测试。Ihara等人使用表面波光谱估计薄膜的材料性质。Matui等人检查了多层系统中确定的弹性模量的准确性。Kishimoto等人确定了功能梯度材料棒的弹性特性。压痕试验是评价薄膜力学性能的方法之一，它是利用压痕器在多层体系中的压痕力和压痕深度的实验数据来估算薄膜弹性模量的方法。在本文中，当使用压痕力和深度的数据，识别薄膜的机械性能和功能梯度材料的机械性能的分布函数的方法将被提出。压入问题的分析在本分析中，具有横截面f（r）的轴对称弹性压头将被穿透到由具有各种机械性能的层组成的弹性半区域中，如图1所示。用三维轴对称弹性理论分析了这种接触问题。然后，通过将Boussinesq势函数φ 3和φ 3代入以下关系式（Miyamoto 1977，Gladwell 1980），可以推导出层、压头和弹性半区中的位移和应力。
This paper describes a method for evaluating material properties of multi-layered systems and functional gradient materials using data obtained from indentation testing. The measurement data collected from the penetration force-depth curves in the test are employed for identifying elastic moduli of thin films and functional gradient materials. An indentation problem is first analyzed on the basis of the three-dimensional axisymmetric theory of elasticity. Analyses of elastic contact problem, which an elastic axisymmetric indenter is penetrated into multi-layered systems and into functional gradient materials, are presented. An inverse analysis for determining Young’s moduli, Poisson’s ratios and radii of the contact area is performed under the assumption that the elastic moduli of the substrate and the indenter, and thicknesses for layers are known. When complex method is used for minimizing an objective function composed of errors, effective sampling of data obtained by penetrating indenters with various radii of curvature into the coated substrate and functional gradient materials is presented. INTRODUCTION Modern electric devices and mass storage devices have frequently multilayered structures to achieve a high performance and functionality. Furthermore, such devices are coated often by metal thin films to protect from the damage of external dusts and environment. It is important to estimate their mechanical properties for improving the reliability of devices and machines. Generally, mechanical properties of thin films deposited on a substrate are different from those of bulk. Hence, we need to know in-situ the mechanical properties of deposited films. However, it is very hard to carry out a test for evaluating the mechanical properties of films in a sub-micrometer thickness. Ihara, et al. estimated the material properties of a thin film using surface wave spectroscopy. Matui, et al. examined the accuracy of identified elastic moduli in a multilayered system. Kishimoto, et al. idetified the elastic properties for a bar of functional gradient materials. Indentation test is one of methods for evaluating the mechanical properties of thin films, which is the one estimating elastic moduli of thin films using experimental data of the force and the depth of an indenter penetrated into a multi-layered system. In the present paper, when data of the indentation force and depth are used, a method for identifying the mechanical properties of thin films and the distribution function of mechanical properties in functional gradient materials will be presented. ANALYSIS OF INDENTATION PROBLEMS In the present analysis, an axisymmetric elastic indenter with a cross section of f(r) will be penetrated into an elastic half-region composed of layers with various mechanical properties as shown in Figure 1. This contact problem is analyzed using the theory of threedimensional axisymmetric elasticity. Then, displacements and stresses in the layers, the indenter and the elastic half-region can be deduced by substituting Boussinesq’s potential functions, ψ and φ 3 , into the following relationships (Miyamoto 1977, Gladwell 1980).