Novel Interface Strengthening And Toughening Method Of Steel/Peek Single Lap Joints With Multi-Scale Combined Features

A novel interface strengthening and toughening method of Steel/PEEK joints was proposed in this article. The multi-scale combined features consisting of macro grooves and micro conical hole array were constructed on the steel sheet surface. The shearing fracture behavior of the Steel/PEEK joints was studied to reveal the influence law and mechanism of the diameter-to-depth ratio gamma of micro conical holes on the infiltration effect of molten PEEK, the maximum shear force and the energy absorption property. Results indicated that the Steel/PEEK joints with different multi-scale combined features possessed great infiltration effect and achieved a much larger maximum shear force than the joints without multi-scale combined feature (the largest improvement was approximately 360% when the gamma of micro conical hole was 1.5). The joints also underwent a typical three-stage failure process. As the gamma of the micro conical holes decreased, the maximum shear force almost increased linearly and the absorbed energy increased exponentially. The load-carrying capacity and energy absorption property of the steel/30% short carbon fiber-reinforced PEEK joint did not improve considerably as desired owing to the non-ideal infiltration effect.