Process-oriented material investigation for effective manufacturing of non-crimp fabric reinforced polymer composites: Fid-Bau Portal

Process-oriented material investigation for effective manufacturing of non-crimp fabric reinforced polymer composites

Schindler, Stefanie / Böhme, Constanze / Helbig, Frank

The production of textile-reinforced polymer composites (TPC) is a demanding interaction of the chosen textile architecture and the applied manufacturing process. Both influence the mechanical behavior of the resulting thermoplastic organic sheet. The aim of this investigation is the production of TPC with bidirectional reinforcement. Therefor the stitch-bonding technique and the multiaxial principle are used to develop a textile semi-finished product according to the so called OLU-Preg® principle. Non-Crimp fabrics (NCF) as multiaxial stitch bonded constructions are used as reinforcement. This accrues a combination of unidirectional continuous glass fibers as the reinforcement-layer and polyamide (PA) non-woven as matrix-layer. Especially, this non-woven fiber-structure ensures a high consolidation (direct impregnation) compared to the impregnation of textiles with thermoplastic melts by means of injection molding. The used glass fibers are modified with a specific bonding agent for PA. Consequently the rovings are exactly adjusted for the matrix material. For improving the handling of the semi-finished product it is consolidate with a thermoplastic PA sewing thread. So the engaged sewing thread consists of a material, which is similar to the matrix. The manufacturing of the novel organic sheets is done in a two-step cold pressing process. Therefor the textile semi-finished product is placed in a chosen structure into a pre-heating station at first. Within the first step the material is applied with temperature (above the melting point of the matrix) and low pressure. This effects the melting of the plastic component and at the same time garanties an impregnation of glass rovings with matrix. The second step is the cold pressing in a typical process temperature range of 30 °C - 50 °C under specified pressure. During this process-step the consolidation within the material takes place. The influence of the sojourn time of the process and the temperature in the first step is considered in studies. The mechanical properties of the composites are investigated under tensile and bending loads, as well as in terms of the energy absorption capacity. Aim is the improvement and validation of a robust process window for this TPC manufacturing. Consequently there is a parameter chance in respect of the mechanical performance of those materials under the point of effective manufacturing. Furthermore there is a comparison of the specific properties with in the meaning of lightweight design. The used NCF organic sheets are characterized by high structural- and product flexibility based on the multiaxial stitch bonding in their textile-based design way. This method meets the requirements of sustainable and lightweight-construction relevant manufacturing of textile-reinforced polymer composites in large series.