Joint interface optimization of all-CFRTP composite honeycomb prepared by ultrasonic multi-spot welding

Abstract

An all carbon fiber reinforced polyetheretherketone (CF/PEEK) composite honeycomb is prepared by the multi-spot ultrasonic welding in this work. The interfacial responses and flat compression failure behaviors of the honeycomb are firstly analyzed. It is found that ultrasonic welding has both positive and negative effects on honeycomb performance. High-frequency vibration results in fiber waviness, which is beneficial to elevating both the bending resistance of the joints and the compression strength of the honeycomb. However, melted EDs also lead to resin-rich areas at the interface. Based on the findings, the multiwall carbon nanotubes/PEEK (MWCNTs/PEEK) energy directors are developed, providing new insights on optimizing the properties of the interface. The experimental results indicate that the interfacial node tensile strength is enhanced by 400 % (1267 kPa) with the MWCNTs content increasing to 7.5 wt%, and the optimized CF/PEEK honeycomb shows more superior specific energy absorption and specific compressive strength than those of the commercial light-weight honeycombs. Moreover, the joint failure behaviors are investigated thoroughly. The addition of MWCNTs is found to induce fiber bridging between the cell walls and facilitate stress transfer through the joint interface. The optimized ultrasonic welding method provides a new opportunity for efficient and volume manufacturing of carbon fiber reinforced composite honeycombs without dimension limitation and large mold costs.