The Analysis of Joint Failure Mode and Effects of Ultrasonic Welding Parameters on the Mechanical Properties of CF / PEEK Composite Joints

ABSTRACT The effects of different welding parameters and water absorption on the properties of ultrasonic welded carbon fiber reinforced polyetheretherketone (CF/PEEK) composite joints were studied. The results show that the lap shear strength (LSS) reaches a maximum of 40 MPa when the welding pressure is 0.35 MPa, the welding time is 3.0 s, and the welding amplitude is 24 um (80%). The mechanical strength and fracture morphology of the welded joints were characterized by a universal testing machine and scanning electron microscope (SEM). The results show that the influence of welding parameters on the LSS of the joint increases first and then decreases. Too low or too high welding parameters will deteriorate the mechanical properties of the joint. In addition, the failure modes of four types of joints were analyzed and summarized. The study found that the boiling time was negatively correlated with the combined LSS value. With SEM observations post‐hygrothermal aging, interfacial morphologies before/after aging were compared; water molecules induced resin swelling, reducing joint strength.