Processing-related consolidation of high speed filament-wound continuous fibre/thermoplastic composite rings

Abstract

Filament winding of composite materials with thermoplastic matrices is more complicated than wer winding of thermosetting composites, due to the much higher viscosity of thermoplastics. Therefore, winding parameters have to be optimized to achieve both good impregnation and high consolidation quality. In this study, the material investigated was impregnated with poly(ethylene terephthalate) powder and had a thin matrix sheath surrounding the flexible glass fibre bundles. It offers a high degree of flexibility compared with stiffer tapes, but is much more difficult to process by a filament winding technique, hence a specially developed filament winding device for processing these flexible fibre bundles is presented. The filament winding technique is the so-called in situ consolidation process, where the incoming yarn is welded to the previously wound surface. The processing parameters in this winding process are mandrel temperature, preheating temperature, nip-point temperature, tow tension, compaction force and winding speed. For this technique, the winding parameters were optimized to obtain a bulk composite structure without any defects if possible. To characterize the consolidation quality, the composite's interlaminar shear strength was determined. Furthermore, the density, flexural modulus and residual stresses in the wound rings were measured. From the point of view of economics, it is very important to increase the winding speed. For this reason a hot air preheating zone was developed. Thus the in situ consolidation process involved a further processing parameter: the preheating temperature. Winding speeds of up to 30 m min⁻¹ were realized using this preheating zone, without diminishing good consolidation quality.