An Analytical and Experimental Study of Longitudinal Creep in Countinous Fiber Composites

本研究采用分析和实验相结合的方法，对单向增强、连续纤维、金属基复合材料（MMCs）的蠕变机理进行了全面的研究。这项工作在三个方面是独一无二的：(1)它试图建立一个模型，明确地说明应变历史，界面滑动，以及随时间变化的基质蠕变；(2)通过对基体、界面和纤维对整体蠕变响应的作用进行实验量化，寻求机理洞察力，而不是预测能力；(3)这是迄今为止唯一一次以瞬态变形机制图的形式总结连续纤维mmc中蠕变机制的应力-温度-时间依赖关系的尝试，这对于预测复合材料在广泛的应力和温度条件下的应变响应和主要变形机制是有价值的。实验程序包括一种新的方法来监测损伤机制在蠕变测试的复合材料的实时。连续纤维复合材料的蠕变响应是复杂的，因为载荷从基体逐渐向纤维传递，导致了瞬态行为，这给机理研究带来了困难。由于纤维-基体界面滑动、内部残余应力与外加应力的相互作用以及随着应力条件的变化基体变形机制的变化，这一过程变得更加复杂。因此，连续纤维增强金属基复合材料（MMC）蠕变的清晰现象学图像尚未出现。该项目有望对连续纤维mmc的蠕变机制，特别是基体和界面变形的作用，产生实质性的基本见解。

9423668 Dutta This research is a comprehensive investigation of creep mechanisms in unidirectionally reinforced, continuous fiber, metal-matrix composites (MMCs), combining both analytical and experimental approaches. The work is unique in three respects: (1) it seeks to develop a model, which explicitly accounts for strain history, interfacial sliding, and time-dependent changes in matrix creep; (2) it seeks mechanistic insight, rather than predictive ability, by proposing experimental quantification of the roles of the matrix, interface and fiber on the overall creep response; (3) it constitutes the only attempt to date at summarizing the stress-temperature-time dependence of creep mechanisms in continuous fiber MMCs in the form of transient deformation mechanism maps, which are valuable in predicting the strain response and dominant deformation mechanisms in composites over a wide range of stress and temperature conditions. The experimental program includes a novel approach to monitor damage mechanisms in real time during creep testing of composites. The creep response of continuous fiber composites is complex because of progressive transfer of load from the matrix to the fibers, resulting in transient behavior which makes mechanistic studies difficult. This is complicated by fiber-matrix interfacial sliding, interaction of internal residual stresses with the applied stresses, and changes in the matrix deformation mechanism with evolving stress conditions. Accordingly, a clear phenomenological picture of creep in continuous fiber reinforced metal-matrix composites (MMC) has not emerged. %%% This project is expected to yield substantial fundamental insight on creep mechanisms in continuous fiber MMCs, particularly with respect to the roles of matrix and interface deformation.