Investigation of Combined Loading Effects during Testing, Modeling and Optimization of Woven Fabrics under Uncertainty: An Application to Forming Processes

机织织物聚合物复合材料，由于其易于成型沿着与重量轻和高强度的组合，已经在包括航空航天、汽车、建筑、船舶和能源的几个主导行业中得到相当大的关注。尽管这种广泛的兴趣，仍然存在着缺乏知识和标准化的测试和分析其在复杂的负载条件下的机械响应。更具体地说，基本的材料变形机制，如纤维张力和织物格架主要是在单独的模式下研究，并有较少的信息的复杂性，织物的行为下的组合加载模式，如同时双轴拉伸和剪切。这种变形模式在实际应用中的例子包括在冲压过程中使用压边圈，以及由双向编织织物复合材料制成的充气梁的加载和卸载。 本研究的目的是进行一种新的，综合的方法，通过机械测试，计算机建模，X射线断层扫描和多目标逆识别的多尺度行为的机织物在组合加载模式下，与提高现有的性能的宏观层次模型用于模拟和优化的复合材料成型工艺在加拿大和其他地方的最终目标。此外，在实践中，有两个来源的不确定性，往往导致不可重复的测试数据和/或不一致的零件质量。这些包括特定于给定变形模式/成形设置的源，以及织物预成型件内的不均匀性所固有的源。认为在利用实验室试验和相关的反演方法进行纱线性能的多目标识别时，这两组不确定性都需要密切关注。因此，为了增加组合加载模式下的建议织物模型的可靠性，不确定性的影响将占在本研究中通过一个强大的实验设计技术。最终，结果将根据实际的成型工艺进行测试，新材料数据将包含在机织物的多标准材料选择工具中。

Woven fabric polymer composites, owing to their ease of formability along with a combination of light weight and high strength, have found considerable attention in several leading industries including aerospace, automotive, construction, marine, and energy. Despite this wide interest, there still exists a lack of knowledge and standardization in testing and analyzing their mechanical responses under complex loading conditions. More specifically, basic material deformation mechanisms such as fiber tension and fabric trellising have been mostly studied under individual modes, and there is less information on the complexity of fabrics behavior under combined loading modes such as simultaneous biaxial tension and shear. Examples of such deformation modes in practical applications include the use of a blank-holder during stamping, and the loading and unloading of inflatable beams made of bidirectional woven fabric composites. The aim of this research is to conduct a novel, integrated approach by means of mechanical testing, computer modeling, x-ray tomography and multi-objective inverse identification of multi-scale behavior of woven fabrics under combined loading modes, with an ultimate goal of enhancing the performance of existing macro-level models used for the simulation and optimization of composite forming processes in Canada and elsewhere. Furthermore, in practice there are two sources of uncertainties that often result in non-repeatable test data and/or inconsistent parts quality. These include sources that are specific to a given deformation mode/forming set-up, and those that are inherent to the heterogeneity within fabric preforms. It is deemed that both groups of uncertainties need a closer attention during multi-objective identification of yarn properties using laboratory tests and the related inverse methods. Hence, in order to add to the reliability of the proposed fabric models under combined loading modes, uncertainty effects will be accounted for in this research via a robust design-of-experiments technique. Eventually, results will be tested against an actual forming process, and new material data will be included in a multi-criteria material selection tool for woven fabrics.