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

9423668 Dutta本研究是对单向增强、连续纤维、金属基复合材料（MMCs）蠕变机制的综合研究，结合了分析和实验方法。 这项工作在三个方面是独特的：（1）它寻求开发一个模型，该模型明确地解释了应变历史、界面滑动和基质蠕变中的时间依赖性变化;（2）它通过提出实验量化基质、界面和纤维对整体蠕变响应的作用来寻求机械见解，而不是预测能力;（3）这是迄今为止唯一以瞬态变形机制图的形式总结连续纤维MMCs蠕变机制的应力-温度-时间依赖性的尝试，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导变形机制是有价值的。 实验方案包括一种新的方法来监测复合材料蠕变试验过程中的真实的时间损伤机制。 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传递到纤维，导致瞬态行为，这使得机理研究变得困难。 这是复杂的纤维-基体界面滑动，内部残余应力与施加的应力的相互作用，并在不断变化的应力条件下的基体变形机制的变化。 因此，在连续纤维增强金属基复合材料（MMC）蠕变的一个明确的现象学图片还没有出现。该项目预计将产生实质性的基本见解蠕变机制在连续纤维金属基复合材料，特别是相对于基体和界面变形的作用。

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.