Design and quality assurance of intrinsic hybrid metal-CFRP lightweight structures

TitleDesign and quality assurance of intrinsic hybrid metal-CFRP lightweight structures
Publication TypeConference Proceedings
Year of Conference2020
AuthorsBretz, Lucas, Günther Fabian, Jost Hendrik, Schwarz Michael, Kretzschmar Vanessa, Pohl Markus, Weiser Lukas, Häfner Benjamin, Summa Jannik, Herrmann Hans-Georg, Stommel Markus, and Lanza Gisela
Conference NameHybrid Materials and Structures
PublisherDGM - Deutsche Gesellschaft für Materialkunde e.V
Conference LocationWeb-Conference, Germany
AbstractThe intrinsic production of metal-CFRP (carbon fiber reinforced polymers) hybrid structures allows a load-path-optimal design of connecting components. The interface of the hybrid part is of particular importance in design, production, and testing due to its force-transferring function. The special feature of the intrinsic connection is a thermoplastic jacket around the metal insert. It dampens vibrations, inhibits corrosions, and smoothens the stiffness gradient at the interface of metal and CFRP. A punched metal insert guarantees the suitability for mass production in the automotive industry, while the plastic jacket maintains a fiber adjusted geometry as well as a structured surface to maximize the joint strength. Load paths, stress distribution, and good drapability are taken into account. Finite element (FE) simulations and experiments are used to design and dimension the insert. Novel FE visualization methods for constructive design are developed and applied. The investigation of design elements on the mesoscale (mm) and microscale (µm) surface roughness shows improvements of the load transfer and reduces the damage propagation. The intrinsic manufacturing is carried out by means of the resin transfer molding (RTM) process. Inline quality assurance starts with the inspection of the preform geometry. The data from two laser light section sensors are used for in-line measurements of complex 3D geometries. Ultrasonic sensors are used to check the curing degree of the resin during the infiltration. Afterwards, in-line quality assurance of the finished hybrid component is carried out by data fusion of laser light section sensors and active thermography. The data fusion enables a three-dimensional representation of the thermographic image and, thus, also a three-dimensional defect localization. Active and passive thermography are suitable for characterizing the component under various load conditions. Damages can be reliably detected using active thermography, while passive thermography allows the in-situ observation of the damage propagation. This allows a detailed insight into the damage mechanisms under quasi-static and cyclic load. It is possible to predict the remaining service life of the component by observing the delamination growth under cyclic mechanical load. The input of the in-line quality information in combination with the damage characteristics into a FE simulation enables the prediction of the individual component performance.