导能筋形状对超声波焊接CF/PEEK接头组织和力学性能的影响

Effect of energy director on microstructure and mechanical properties of CF/PEEK joints obtained by ultrasonic welding

关键词:  超声波焊接  碳纤维增强聚醚醚酮  导能筋  界面温度  力学性能

Key words:  ultrasonic welding  CF/PEEK  energy directors  interface temperature  mechanical property

摘要:

通过超声波焊接方法实现碳纤维增强聚醚醚酮（CF/PEEK）试件的连接，重点研究了导能筋形状对接头组织和力学性能的影响. 结果表明，当使用矩形和三角形导能筋时，由于导能筋的粘弹性变形大，界面的升温速率快，且界面温度高，接头的热影响区（HAZ）较大，在热影响区由于碳纤维和树脂界面有较大的热应力，容易产生裂纹等缺陷，液态树脂流动方式很容易造成气孔缺陷，接头的力学性能较差. 使用平面导能筋，当超声作用时间为0.9 s时，界面形成了良好的连接，液态树脂流动方式优于三角形和矩形导能筋，接头中不会出现气孔缺陷，接头的抗剪强度可以达到28 MPa.

Abstract:

The ultrasonic welding was employed to connect carbon-fiber-reinforced polyetherether-ketone (CF/PEEK) composites. The effects of the shapes of energy directors (ED) on the microstructure and mechanical property of joints were mainly investigated. The results showed that the heat affected zone (HAZ) of the joints was larger when the rectangular or triangular ED were used, which was caused by the high viscoelastic deformation of EDs, rapid heating rate at the interface and high interface temperature. Thermal stress was larger at the interface between carbon fiber and resin in the HAZ, which easily resulted in cracks and other defects. In addition, the flow pattern of ED made void defects easily occurred. Therefore, the joints had poor mechanical property. When flat ED was used, the interface formed a good connection with ultrasonic action time of 0.9 s. The flow pattern of flat ED was better than that of the rectangular and triangular ED, so no void defects occurred in joints whose tensile-shear strength could reach 28 MPa.