The forming behaviour of a unidirectional non-crimp fabric (UD-NCF) consisting of polyamide stitches with a tricot-chain stitching pattern is explored. Notably, there are no stabilising tows orientated transverse to the main tow direction in this fabric, a common feature in many ‘quasi’ UD-NCFs, this allows extension of the stitch in the transverse direction under certain loading conditions. The lack of stabilising tows introduces a possible low-energy deformation mode to the UD-NCF, which is absent in biaxial fabrics and to a large extent in ‘quasi’ UD-NCFs. The in-plane shear behaviour is initially investigated using both standard ‘tightly-clamped’ picture frame tests and uniaxial bias extension tests. Preliminary results show a dramatic difference in results produced by the two test methods. During the picture frame test, fibres can be subjected to unintended tension due to sample misalignment in the picture frame rig. To mitigate error arising from this effect, the picture frame test procedure is modified in two different ways: by using an intentional pre-displacement of the picture frame rig, and by changing the clamping condition of test specimen. Results show that the modified picture frame test data contain less error than the standard ‘tightly-clamped’ test but also that the shear stiffness of the UD-NCF is notably lower when measured in the bias extension test compared to the picture frame test, mainly due to the difference in loading conditions imposed during the two tests.

研究了由具有经编链式缝合图案的聚酰胺缝线组成的单向无屈曲织物（UD-NCF）的成形行为。值得注意的是，这种织物中没有横向于主丝束方向的稳定丝束，这是许多“准”UD-NCF 的共同特征，这允许在某些负载条件下缝线沿横向方向延伸。缺乏稳定丝束给 UD-NCF 引入了一种可能的低能变形模式，这种模式在双轴织物中不存在，并且在很大程度上在“准”UD-NCF 中不存在。最初使用标准“紧密夹紧”相框测试和单轴偏置延伸测试来研究面内剪切行为。初步结果显示两种测试方法产生的结果存在显着差异。在相框测试过程中，由于相框装置中的样品未对准，纤维可能会受到意外的张力。为了减轻这种影响产生的误差，以两种不同的方式修改相框测试程序：通过使用相框装置的有意预位移，以及通过改变测试样本的夹紧条件。结果表明，修改后的相框测试数据比标准“紧夹”测试包含的误差更小，但与相框测试相比，在偏置延伸测试中测量时，UD-NCF 的剪切刚度明显较低，这主要是由于两次测试期间施加的加载条件不同。通过使用相框装置的有意预位移，并改变测试样本的夹紧条件。结果表明，修改后的相框测试数据比标准“紧夹”测试包含的误差更小，但与相框测试相比，在偏置延伸测试中测量时，UD-NCF 的剪切刚度明显较低，这主要是由于两次测试期间施加的加载条件不同。通过使用相框装置的有意预位移，并改变测试样本的夹紧条件。结果表明，修改后的相框测试数据比标准“紧夹”测试包含的误差更小，但与相框测试相比，在偏置延伸测试中测量时，UD-NCF 的剪切刚度明显较低，这主要是由于两次测试期间施加的加载条件不同。