Trockene Preforms für komplexe Faserverbundkunststoffbauteile

By locally fixing the structure, the reproducibility of complex preforms can be greatly improved during pattern cutting, handling, batching, and assembly processes. In order to simplify the handling and draping of the textile structure, to keep the geometry deviations as marginal as possible and to secure the location of the fibers in the preform, a local fixation via binder or laser, aligned with the pattern cutting geometry, is proposed. Various textile stock with different patterns, thread thicknesses, densities and compositions (glass fibers (GF) and hybrid yarns (GF+PP)) were examined. A thermoplastic matrix was used to produce the laminates. In the production of lightweight structures using textile reinforcements, sometimes mechanical properties of the component can be adversely affected by undefined stacking of the reinforcement textiles when defining and configuring complexly curved free form surfaces. Pattern cuts are developed directly in the model geometry so the reinforcement structures can be correctly placed according to loads in the desired 3D-components without requiring reworking. In this research project, 4 reference geometries were chosen and subsequently investigated theoretically (calculations) and practically (experiments). The pattern cut was derived from the 3D geometry with inverse computational methods. A subsequent analysis of occurring deformation was conducted to distinguish areas with even slight fiber displacement or shifts in angle, which are candidates for local fixation. In order to evaluate the textile structures' shear behavior, picture frame tests were developed at the ITM [3]. Predictions of expected deformability (drapability) were derived from the calculated shear load-shear angle diagram. The increased local stiffness of the separate pattern cuts enables better and simpler handling and draping reproducibility. Necessary post-finishing processes to achieve good selvage quality are reduced to a minimum