Direct adhesion of CFR-thermoplast on steel - testing and simulation of the lap shear fracture

In this work a novel joining technology by direct adhesion of carbon fiber-reinforced thermoplastic (CFRTP) with polyamide 6 matrix on steel is investigated. Based on endless fiber-reinforced thermoplastic tapes a unidirectional layup is manufactured with the FiberForge RELAY®. Here, the layup is stacked by ultrasonic welding points and is so far not consolidated to a laminate. Two preforms are positioned into a tooling with a metal sheet in between. Afterwards the joining process is carried out by applying heat and pressure on the tooling. The manufactured hybrid double lap joint specimens are conditioned according to the standard DIN EN ISO 1110. Then, tension tests are performed evaluating different surface treatments on the metal sheet in terms of joint strength. Here, joint strength up to 19 MPa is achieved. Based on these results one of the surface treatments is characterized by DCB and ENF tests to get the energy release rates in Mode I and Mode II, respectively. These values are used as input parameters for the cohesive zone modeling of the interface in Abaqus. Finally the double lap joint tension test is simulated and shows a good correlation with the test result.