Thermoplastic braid-trusion is a composite manufacturing process that combines braiding and pultrusion of hybrid yarns containing reinforcement and polymer fibers. During pultrusion, the melting of the polymer fibers leads to complex morphological changes at the macro, meso and micro scales. We introduce here a multiscale numerical simulation methodology to model this process. In this methodology, braided yarns are modeled as bundles of virtual discrete fibers using chains of truss elements. A thermoplastic composite braided rod was pultruded according to the simulated braid-trusion. During braid-trusion, it was observed that the braid architecture was significantly modified, which was reliably predicted by the model through macroscopic measurements of 7.6% pitch elongation, 44.0% diameter reduction, and 45.0% nominal angle reorientation. The model also predicts yarns’ cross-section area having high local fiber volume fraction of about 60% due to yarn compaction during pultrusion. These predictions of mesoscopic morphology and internal geometry are quantitatively validated using X-ray micro-computed tomography (CT) scans of the braid-truded rod. Three local fiber orientation distributions of the in-plane, out-of-plane, and with respect to the longitudinal braid axis are extracted using micro-scale analysis of virtual fibers. We found that a significant amount of fibers are oriented around specific radii ranging from 30–70% and 60–100% of the outer radius before and after pultrusion, respectively. By contrast, the local fiber orientation is uniformly distributed along the pitch length. The microscale model also shows considerable discrepancies between local and nominal braid angles.

热塑性编织成型是一种复合制造工艺，它结合了包含增强纤维和聚合物纤维的混合纱线的编织和拉挤成型。在拉挤过程中，聚合物纤维的熔化导致宏观、中观和微观尺度上的复杂形态变化。我们在这里介绍了一种多尺度数值模拟方法来模拟这个过程。在这种方法中，编织纱线被建模为使用桁架元素链的虚拟离散纤维束。根据模拟的编织-挤压拉挤热塑性复合编织棒。在编织挤压过程中，观察到编织结构发生了显着改变，模型通过 7.6% 节距伸长、44.0% 直径减小和 45.0% 标称角度重新定向的宏观测量可靠地预测了这一点。该模型还预测，由于拉挤过程中纱线的压实，纱线的横截面积具有约 60% 的高局部纤维体积分数。使用 X 射线显微计算机断层扫描 (CT) 扫描编织牵引杆对这些细观形态和内部几何形状的预测进行了定量验证。使用虚拟纤维的微尺度分析提取平面内、平面外和相对于纵向编织轴的三个局部纤维取向分布。我们发现，在拉挤成型前后，大量纤维分别围绕外半径的 30-70% 和 60-100% 的特定半径定向。相比之下，局部纤维取向沿节距长度均匀分布。微尺度模型还显示了局部编织角度和名义编织角度之间的相当大的差异。