This experimental work aims at evaluating the mechanical and failure behavior of adhesive-bonded single-lap joints made of a thermoplastic composite 3D-printed via Fused Filament Fabrication technology. Carbon fiber was selected as the reinforcement and used in the form of both short and continuous fibers embedded in the Nylon-6 matrix, forming the composite's hybrid structure. An approach based on progressive improvement of surface treatment effectiveness (solvent degreasing, abrasion, and low-pressure plasma) has been adopted to verify how the additively-manufactured composite responds to bonding when increased interfacial adhesion is attained by preparing the outer printed layer. Roughness measurements, wettability evaluations, and XPS analyses have been carried out to assess any modifications of morphology and functionalization exhibited by the different surfaces after treatment. The experimental findings demonstrate that the intrinsic non-homogeneity of 3D-printed composites is emphasized when low-pressure plasma is used, as it generates interfacial bonds between adhesive and adherend that are more effective than the interlaminar ones within the substrate. In this condition, the ultimate resistance of the joint corresponds to that of the base material. In particular, fracture-mechanism analysis allowed precise identification of the crack path, highlighting defects and current limitations of the additively-manufactured system and suggesting pivotal aspects to develop in future work to improve joint performance.

这项实验工作旨在评估由热塑性复合材料制成的胶粘单搭接接头的机械性能和失效行为，并通过3D打印熔融长丝制造技术。选择碳纤维作为增强材料，并以短纤维和连续纤维的形式嵌入尼龙6基体中，从而形成复合材料的混合结构。已经采用了一种基于逐步改善表面处理效果（溶剂脱脂，磨蚀和低压等离子体）的方法，以验证当通过准备外部印刷层而获得增加的界面粘合力时，增材制造的复合材料如何响应粘合。已经进行了粗糙度测量，润湿性评估和XPS分析，以评估处理后不同表面表现出的形态和功能化的任何变化。实验结果表明，当使用低压等离子体时，会强调3D打印复合材料的固有非均质性，因为它会在胶粘剂和被粘物之间产生比基材内的层间键更有效的界面键。在这种情况下，接头的极限电阻与基材的极限电阻相对应。尤其是，断裂机理分析可以精确识别裂纹路径，突出显示增材制造系统的缺陷和当前局限性，并建议在今后的工作中要发展的关键方面，以改善接头性能。接头的极限阻力对应于基础材料的极限阻力。尤其是，断裂机理分析可以精确识别裂纹路径，突出显示增材制造系统的缺陷和当前局限性，并建议在今后的工作中要发展的关键方面，以改善接头性能。接头的极限阻力对应于基础材料的极限阻力。尤其是，断裂机理分析可以精确识别裂纹路径，突出显示增材制造系统的缺陷和当前局限性，并建议在今后的工作中要发展的关键方面，以改善接头性能。