Mechanical behaviour of novel textile multi-axial reinforced thermoplastic composites made from hybrid yarns

摘要

Textile reinforced thermoplastics offer huge application potentials for a rapid manufacturing of components close to the final contours with a load adapted property profile and versatile possibilities of integrating functions. However, an application of these new textile reinforced materials requires the knowledge of the composite behaviour, particularly regarding directional dependent stiffness, strength, thermal and medial extension and long-run properties. But the essential experimental investigations for that purpose, under consideration of the distinct anisotropy, the various textile arrangements and the technically relevant environmental conditions, require an extensive expenditure of time. Presently, for a practical application of textile reinforced thermoplastics, there is a lack of the corresponding material models and the associated material parameters. Within the theoretical and experimental investigation, for the young material class of multi-axial reinforced composites with thermoplastic matrix, basic material and failure models will be presented and verified. Essential mechanicals questions will be clarified regarding the definition and the description of representative textile equivalent layers as well as their arrangement to design practical textile reinforced composites. The required characteristic functions and arbitrary parameters: elasticity constants, strength values and degradation parameters, have been determined in uniaxial and multiaxial tests using flat specimen and tube specimen, respectively. To include the-influence of process-related parameters from the textile processing, corresponding experimental tests have been performed which document the influence of the particular processing steps on the mechanical properties in an all-embracing way. For the manufacturing of the tube specimen, the ILK substantially developed two new manufacturing technologies: the skidding method and the shrink hose method, respectively. For complex composites made of hybrid fabrics, 3D-weft knitted fabrics, "spacer fabrics" or "spacer preforms", the proposed model ensures an efficient method of including material and process data to the mechanical description procedure and provides fundamental knowledge about this new material group.