Thermoplastic carbon fiber-reinforced epoxy has potential in the fields of aerospace, vehicle, and medical equipment, due to nontoxicity, adequate cost savings, and outstanding mechanical properties. Sensitivity to welding heat of the thermoplastic carbon fiber-reinforced epoxy is an urgent issue due to the low glass transition temperature (T _g). High pressure–amplitude ratio ultrasonic spot welding is used to join the low T _g thermoplastic carbon fiber-reinforced epoxy, which provided sufficient energy and pressure for suppressing the vibration and eliminating the stress relaxation to improve the stability of the material to welding heat. The molten area increased at the interface, whereas the entanglement of molecular chains was promoted under adequate pressure. The tensile shear force reached 4.6 kN with the welding pressure of 4.8 MPa, the amplitude of 44.1 μm and the welding time of 800 ms. The primary formation mechanism includes bonding of polymer, tangling of carbon fibers, and polymer, and strengthening between polymeric layers. The high pressure–amplitude ratio ultrasonic spot welding has the feasible and potential to join the low T _g thermoplastic composites.

中文翻译：

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热塑性碳纤维增强环氧树脂的高压幅比超声点焊

热塑性碳纤维增强环氧树脂由于无毒、足够的成本节约和出色的机械性能，在航空航天、车辆和医疗设备领域具有潜力。由于低玻璃化转变温度（Tg），热塑性碳纤维增强环氧树脂对焊接热的敏感性是一个紧迫的 问题_。采用高压幅比超声波点焊连接_低Tg 热塑性碳纤维增强环氧树脂，为抑制振动和消除应力松弛提供了足够的能量和压力，以提高材料对焊接热的稳定性。界面处的熔融面积增加，而在足够的压力下促进了分子链的缠结。拉伸剪切力达到4.6 kN，焊接压力为4.8 MPa，振幅为44.1 μm，焊接时间为800 ms。主要形成机制包括聚合物的结合、碳纤维和聚合物的缠结以及聚合物层之间的强化。高压幅比超声点焊具有连接低T _g热塑性复合材料的可行性和潜力。