Abstract Wrinkling is one of the most common flaws taking place during the forming process of textile composites with complex mould geometries. It is of importance to designers to be able to predict the minimum amount of forces that are required to diminish the wrinkles in useful regions of the final product, through applying appropriate boundary conditions enforced at the blank holders. Towards this goal, herein a multi-step biaxial bias extension (MBBE) characterization test has been proposed to assess the magnitude of the required transverse de-wrinkling forces that can smooth out wrinkles of different sizes, formed at different shear angles of a plain weave fabric. Employing image processing and 3D scanning during the MBBE test, the local shear angles and dimensions of wrinkles were characterized and correlated to the measured forces. It was shown that applying excessive transverse loads to yarns can result in a very narrow formability window and eventually cause fiber breakage, hence suggesting critical role of forming optimization, given different part shapes and fabric types.

中文翻译：

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机织织物起皱/去皱特性的多步双轴偏置延伸测试：走向最佳成型设计指南

摘要 起皱是复杂模具几何形状的纺织复合材料成型过程中最常见的缺陷之一。对于设计者来说，通过在压边器上施加适当的边界条件，能够预测减少最终产品有用区域中的皱纹所需的最小力是很重要的。为了实现这一目标，本文提出了多步双轴偏置延伸 (MBBE) 特性测试，以评估所需的横向去皱力的大小，该力可以消除平纹组织不同剪切角下形成的不同尺寸的皱纹织物。在 MBBE 测试过程中使用图像处理和 3D 扫描，局部剪切角和皱纹尺寸被表征并与测量的力相关联。