Traditional laminated composites have fibres oriented only in the in-plane of the laminate due to their manufacturing process, and are therefore very susceptible to transverse cracking and delamination from out-of-plane actions. Delamination can considerably reduce the load bearing capacity of a structure hence several reinforcement solutions, based on the principle to add out-of-plane reinforcement to the 2D fabric, have been explored to enhance the delamination resistance. However, the usual textile technologies for Z-reinforcement such as weaving, knitting, stitching, z-pinning, and tufting generates perturbations that may alter the in-plane mechanical properties. Although tufting is a single needle and single thread based one side stitching (OSS) technique which can incorporate almost tension free through the thickness reinforcement in a material, various types of microstructural defects may be created during the manufacturing process and lead to a degradation of the in-plane properties of the composite. Moreover, due to awareness in environmental concerns, the development and use of eco-friendly biocomposites to replace synthetic ones has been increasing. This research work investigates the effect on in plane mechanical properties of adding through the thickness reinforcement (TTR) by tufting in a flax based composite laminate to improve the transversal strength. The glass fibre tufted laminates of 550 g/m2 flax fibre were moulded using a 38% biobased thermoset resin by vacuum bag resin transfer moulding (VBRTM). The tufted and un-tufted in-plane mechanical properties of green biocomposite were determined in tension, compression and shear in accordance with ASTM 3039, ASTM D7137 and EN ISO 14130, using universal INSTRON 1186 and MTS 20 M testing machines. The quantification of the in-plane mechanical properties established a reduction of the in plane tensile mechanical properties, due to tufting, whereas the reduction effects are marginal in compression. As expected, the glass fibre tufts strength the connection between core and skin of the composite so that the interlaminar shear strength, deduced from flexural tests with small span-to-thickness ratio, is increased. Thanks to Digital Image Correlation (DIC) performed during shear tests, an increase in interlaminar shear modulus is highlighted.

中文翻译：

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簇绒对亚麻纤维增强绿色生物复合材料面内力学性能影响的研究

传统的层压复合材料由于其制造过程而具有仅在层压材料的面内取向的纤维，因此非常容易受到横向裂纹和由于面外作用而分层的影响。分层会显着降低结构的承载能力，因此，基于向2D织物添加平面外增强的原理，已探索了多种增强解决方案以增强抗分层性。但是，用于Z增强的常用纺织技术（例如编织，编织，缝合，Z钉扎和簇绒）会产生扰动，这些扰动可能会改变面内机械性能。尽管簇绒是一种基于单针和单线的侧缝（OSS）技术，该技术可以通过材料中的厚度增强几乎消除张力，但是在制造过程中可能会产生各种类型的微结构缺陷，并导致其质量下降。复合材料的面内特性。而且，由于对环境问题的认识，开发和使用生态友好的生物复合材料来代替合成生物复合材料已经越来越多。这项研究工作研究了通过在亚麻基复合层压材料中簇绒以提高横向强度而对厚度增强剂（TTR）进行添加对平面内机械性能的影响。550 g / m2亚麻纤维的玻璃纤维簇绒层压板使用38％生物基热固性树脂通过真空袋树脂传递模塑（VBRTM）进行模塑。使用通用的INSTRON 1186和MTS 20 M测试机，按照ASTM 3039，ASTM D7137和EN ISO 14130，在拉伸，压缩和剪切下确定绿色生物复合材料的簇绒和未簇绒的面内机械性能。平面内机械性能的量化确定了由于簇绒导致的平面内拉伸机械性能的降低，而该降低效果在压缩方面是微不足道的。正如预期的那样，玻璃纤维簇增强了复合材料的纤芯和蒙皮之间的连接，从而提高了由跨度和厚度比较小的挠曲测试得出的层间剪切强度。