Toughness, Strength, and R-Curve Behavior of Microcracking Materials (Materials Research)

这项研究是工作的继续（以前的研究 根据DMR-8305800）了解韧性和应力- 导致陶瓷材料的微裂纹。 调查 着重讨论以下问题：1）计算机计算和 陶瓷中裂纹生长的模拟， 重要的物理材料参数，2）表征 陶瓷-玻璃复合材料系统， 使用小角中子散射的诱导微裂纹，3） 陶瓷材料的强度-韧性关系的研究， 陶瓷-玻璃复合材料。 在多相陶瓷材料中，微裂纹是常见的， 特别是当有一个明显的差异， 几个相之间的热膨胀系数 存在于材料中。 这种现象可以用来剪裁 材料的机械性能，通过适当选择 各种相，以允许消除微裂纹或 在常规裂纹附近引入微裂纹， 需要的话 微裂纹的存在通常会降低 应力强度在尖端的规则裂纹，从而导致 阻止裂缝扩散 这种现象导致 陶瓷在使用中更坚固， 压力下的灾难性故障 目前的研究是 旨在增加对这一现象的理解，并允许 更坚固的陶瓷设计。

This research is continuation of work (previous research under DMR-8305800) on understanding the toughness and stress- induced microcracking of ceramic materials. The investigation emphasizes the following topics: 1) computer computation and modelling of the growth of cracks in ceramics which incorporates the important physical materials parameters, 2) characterization of ceramic-glass composites systems which demonstrate stress- induced microcracking using small angle neutron scattering, 3) study of the strength-toughness relationships for ceramics and ceramic-glass composites. In multiphase ceramic materials, microcracking is common, especially when there is a pronounced difference in the coefficient of thermal expansion between the several phases present in the material. This phenomenon can be used to tailor the mechanical behavior of the material, by proper selection of the various phases, to allow elimination of the microcracks or introduction of the microcracks in the vicinity of regular cracks as desired. The presence of microcracks can often reduce the stress intensity at the tips of regular cracks, and thereby cause the regular cracks to stop propagating. This phenomenon causes the ceramic to be tougher in service, and less susceptible to catastropic failure under stress. The present research is designed to increase understanding of the phenomenon, and allow design of tougher ceramics.