Highly aligned discontinuous fiber composites have been pursued with the goal of achieving high performance properties with the formability of short fiber composites. The feedstock consists of a highly aligned discontinuous fiber preform which can be combined with thermoplastic or thermoset resins to create prepreg that can extend in the fiber direction. With this added benefit of lamina extensibility in the fiber direction, a methodology is needed to determine the degradation of material quality with applied forming strain. A framework is established to define a forming process window which sets the optimal process conditions—temperature and strain rate—for maintaining lamina uniformity after deformation. Digital image correlation was used to measure strain uniformity for samples stretched in uniaxial tension at constant temperature and strain rate. The experimental results show that forming strain rate should increase with increasing process temperature. The process window established in this work will be used to ensure that material uniformity can be optimized in manufacturing trials and other material characterization evaluations.

中文翻译：

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建立热固性定向不连续纤维复合材料成型工艺窗口的方法

人们一直在追求高度排列的不连续纤维复合材料，其目标是通过短纤维复合材料的可成型性实现高性能。该原料由高度排列的不连续纤维预制件组成，可与热塑性或热固性树脂组合，形成可沿纤维方向延伸的预浸料。由于薄片在纤维方向上的延展性带来了额外的好处，因此需要一种方法来确定材料质量随施加的成形应变的退化。建立了一个框架来定义成形工艺窗口，该窗口设置了最佳工艺条件（温度和应变速率），以在变形后保持层状均匀性。使用数字图像相关性来测量在恒定温度和应变速率下单轴拉伸的样品的应变均匀性。实验结果表明，成形应变率应随着工艺温度的升高而增加。这项工作中建立的工艺窗口将用于确保在制造试验和其他材料特性评估中优化材料均匀性。