Daniel Weck

Combined joining technique for thermoplastic composites with embedded sensor networks

Lightweight components suitable for high-volume production are realizable by utilizing textile-reinforced thermoplastics. These composite structures can be equipped with additional functionalities by embedding sensor networks. With regard to assembly processes, material- and function-adapted joining techniques are required to connect such components efficiently. Therefore, the joint should enable both the transmission of mechanical loads and electrical signals. In order to fulfill these requirements, a combined joining technique based on blind riveting is analyzed in this article. Specimen plates made of glass-fiber-reinforced polypropylene were fabricated by compression molding. They contained adapted conductors embedded between the glass-fiber-reinforced polypropylene layers. In a next step, specimens were joined by blind riveting. The experimental analysis of several joint configurations revealed differences in interface quality and electrical performance. Finally, the reliability of the selected joining concept was verified by the experimental investigation of single-lap specimens under thermal and tensile loading.

Manufacturing and Process-based Property Analysis of Textile-Reinforced Thermoplastic Spacer Composites

Novel woven spacer fabrics based on hybrid yarns are suitable for an efficient fabrication of three-dimensional composite structures in high volume production. In this paper, an innovative manufacturing process with short cycle times and high automatisation is introduced for textile-reinforced thermoplastic spacer structures suited for bending load cases. The different process steps hybrid yarn fabrication, weaving technology for three-dimensional textile preforms and consolidation with unique kinematics and hot pressing technology are described in detail. The bending properties of the manufactured spacer structures are evaluated by means of experiments as well as finite element simulations. Numerical parametric studies are performed in order to validate the influence of manufacturing tolerances on the bending stiffness of the spacer structures.

Combined Detachable Joints for Textile Reinforced Thermoplastic Composites with Embedded Sensor Networks

In regard to the realization of innovative lightweight constructions, textile reinforced composites show outstanding mechanical properties, e. g. adjustable high specific stiffness and strengths. Furthermore, these materials enable a process immanent integration of functional elements (f. e. conductors, sensors, actuators or electronic components) directly into the composite structure due to their layered built up. Currently, no joining technologies for such function integrative composite parts exists, which enable a simultaneous mechanical and electrical load transfer from part to part by only one joining element type. Therefore, the paper focuses on detachable functional interfaces, which enable the mechanical connection of two join partners and the transfer of electrical signals by contacting the composite embedded conductors. Investigations in regard to the selection of suitable joining elements and their behavior under mechanical and thermal loads are performed. The investigations show that the electrical resistances are low and not affected significantly by rising tensile loads or repetitive joining operations. Tensile tests using both single lap shear and double lap shear specimens show that the electrical contact almost exists until the mechanical failure of the joints occurs.