MEASURMENT OF R-CURVES FOR CERAMIC COMPOSITS,AND ITS MACROMECHANIC ANALYSIS

陶瓷复合材料R曲线测量及其宏观力学分析

基本信息

批准号：
07455427
负责人：
NISHIDA Toshihiko
金额：
$ 0.32万
依托单位：
KYOTO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

In order to make clear the micromechanisms governing the fracture behavior of materials, it is necessary to pursue precise characterizations giving the depecdence of the resistance showed by the material to crack propagation on the crack length (R-curve behavior). In this work, some basic problems related to the stable propagation of cracks in brittle materials have been solved. First, a technique to introduce a sharp (mum scale diameter) notch in the specimen has been developed. Then, the problem of stabilizing the crack propagation through the use of a stabilizer apparatus using the bending geometry (according to JIS) has been overcome. In such a way, the routine procedure to obtain R-curve in even very brittle materials has been well established and applied to two type of materials : 1) composite materials reinforced on the micron scale by whiskers or fiber-like (elongated) grains and, 2) composite materials reinforced on a larger scale by long fibers.In addition to fracture mechanics characterizations, in situ spectroscopy measurements have been performed to characterize the mechanisms of fracture on the microstructural scale. As a result of this characterizations, it has been shown that mechanisms operating in the wake of the crack tip, namely, the elastic or frictional bridging, play the major role in hampering fracture propagation in brittle solids.Finally, precise characterizations of the shear resistance of fiber-reinforced materials have also been performed with particular emphasis on relating the microscopic mechanism of interface debonding to the macroscopic failure process by shearing. The results and the final interpretation on the above fracture processes have then summarized and presented in scientific papers.

为了清除材料断裂行为的微观力学，有必要进行精确的特征，从而使材料的抗药性脱落以在裂纹长度（R-curve行为）上表现出抗裂纹。在这项工作中，已经解决了与脆性材料中裂纹稳定传播有关的一些基本问题。首先，已经开发了一种在样品中引入尖锐（MUM尺度直径）缺口的技术。然后，克服了通过使用稳定器使用弯曲几何形状（根据JIS）稳定裂纹传播的问题。以这种方式，即使在非常脆的材料中获得R-Curve的常规程序已得到很好的确定，并应用于两种材料：1）通过晶须或纤维样（细长）晶粒和纤维状（细长）谷物和，2）复合材料通过长纤维在更大范围内增强。除了断裂力学的特征外，已经进行了原位光谱测量，以表征微结构尺度上断裂的机制。由于这种特征，已经表明，在裂纹尖端（即弹性或摩擦桥接）中运行的机制在阻碍脆性固体中的裂缝繁殖时起着主要作用。剪切阻力的精确表征还进行了纤维增强的材料，特别是通过剪切将界面剥离的微观机制与宏观失败过程有关。然后，对上述断裂过程的结果和最终解释总结了科学论文并提出。