Micromechanics-Based Approach to the Design of Ceramic/Metal Functionally Graded Materials.

基于微力学的陶瓷/金属功能梯度材料设计方法。

基本信息

批准号：
06452318
负责人：
WAKASHIMA Kenji
金额：
$ 4.54万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

This investigation is concerned with a computational mechanics-based architecture of ceramic-to-metal graded multilayr constructions, called "functionally graded materials (FGM) ", their prime application target being directed toward the improvement of conventional thermal barrier coatings in hot structural components. The most important feature of these multilayr constructions is a tailorability of heat-shielding and thermal stress-mitigating functions through compositional and microstructural control of individual composite layrs in between the outermost fully ceramic and fully metallic ones. The tailoring as such involves heat conduction and stress analyzes under various prescribed conditions of thermomechanical loading and, because of the dual-scale heterogeneity inherent to the FGM structure, these analyzes require both "macromechanical" and "micromechanical" approaches.The computational procedure developed in the present work features an inelastic analysis that permits yielding a … More nd plastic flow of the metal phase. This is formulated via a straightforward extension of the classical laminated plate theory, wherein a micromechanical model of constrained plasticity is incorporated to derive the lamina constitutive equation in the elastoplastic regime. A systematic computational study has been carried out to demonstrate how the distributions of thermal stresses change by changing the gradations in composition and microstructure.Some related experiments have also been done on the zirconia-nickel system using discshaped samples fabricated by hot pressing composition-graded multilayr green compacts of powder mixtures. These include (i) the measurement of steady state through-the thickness temperature distributions by means of thermography for "in situ" determination of the thermal conductivities of individual layrs, (ii) "disc-bending" tests of compositionally uniform samples corresponding to individual layrs in order to determine their failure strengths under equi-biaxial loading conditions, and(iii) repeated thermal loading tests of graded multilayr samples under quasi-unidirectional conditions of heat flow.A general conclusion drawn from this investigation is that the FGM concept is quite attractive indeed and the present computational mechanics-based approach can produce many useful guidelines to the FGM architecture. Less

这项投资涉及基于计算机械的陶瓷到金属分级多层结构的结构，称为“功能分级材料（FGM）”，其主要的应用目标是针对改善热结构组件中常规热屏障涂料的改善。这些多层结构的最重要特征是通过组成和微观结构控制在最外层的完全陶瓷和完全金属的元素之间的组成和微结构控制，从而可以调整热屏蔽和热应力降低功能。这样的剪裁涉及在各种热力学负荷条件下进行的热传导和应力分析，并且由于FGM结构固有的双尺度异质性，这些分析需要“摩克机械”和“微力力学”和“微机械”方法。在当前的工作中开发的计算过程特征是允许在弹性分析的情况下允许均衡量的固定量。这是通过经典层压板理论的直接扩展来制定的，其中纳入了约束可塑性的微力模型，以在弹性塑性方面得出层状组成方程。已经进行了一项系统的计算研究，以证明如何通过改变组成和微观结构的等级来改变热应力的分布。还使用热按压组成的组合物划分的多层多层绿色的粉末混合物制造的圆度样品在氧化甲虫系统上进行了一些相关的实验。这些包括（i）通过热量表测量稳态通量温度分布，以“原位”测定单个Layrs的热导率的“原位”测定，（ii）“盘式弯曲”测试，对对应于单个Layr的组合样品的“盘式弯曲”测试，以确定其在等于双轴载荷条件下的乘积乘积和（IIII）重复的（IIII）的乘积测试，以及（IIII）的重复测试，以及（IIII）。热流的准空间条件。从这项投资中得出的一般结论是，FGM概念确实很有吸引力，而目前的基于计算的方法可以为FGM体系结构提供许多有用的准则。较少的