Weld lines (WLs) are among the most detrimental defects affecting polymer composites. While they have been extensively studied in short fibre composites, their effects on tow-based composites are largely unknown. In this study, tow-based carbon fibre sheet moulding compounds were used to compression mould plates with WLs. Three different WLs configurations were considered: WLs in (1) low-flow moulding, (2) high-flow moulding with opposite meeting fronts and (3) high-flow moulding with adjacent meeting fronts. The tensile strength of the WL specimens was between 48% and 88% of the pristine material. Tows were highly distorted in the region of the WLs, both in-plane and out-of-plane, and a significant tow re-orientation parallel to the WLs was recorded. The meeting flow fronts acted as a physical barrier to each other, preventing tows to intermingle. A comprehensive characterisation of the effects and the main detrimental factors of WLs in tow-based composites was thus presented.

熔接线（WL）是影响聚合物复合材料的最有害的缺陷之一。尽管已在短纤维复合材料中对它们进行了广泛的研究，但它们对丝束复合材料的影响尚不清楚。在这项研究中，基于丝束的碳纤维片状模塑料用于压制带WL的模板。考虑了三种不同的WL配置：（1）低流动模制中的WL，（2）具有相对的汇合前沿的高流动模塑，以及（3）具有相邻的汇合前沿的高流动模塑。WL样品的拉伸强度为原始材料的48％至88％。丝束在WL区域内（平面内和平面外）都高度变形，并且记录了与WL平行的显着丝束重新定向。会议流前沿相互之间是一个物理屏障，防止了丝束相互混合。