Adaptation and study of a filament winding machine for in-situ consolidation of thermoplastic composites

This thesis studies the automated filament winding process. Its two objectives are: 1) The restauration of a filament winding system functionality and system adaptation for the manufacturing of thermoplastic materials using commingled yarns and 2) The study of the effect of the system parameters on the consolidation degree of the final parts, and defining the processing window for the studied material that optimize its consolidation. In order to recommission the filament winding system the numeric control machine is restored and the necessary systems for the machine adaptation for manufacturing thermoplastic composite materials are designed. The newly implemented components are calibrated to obtain the systems work range and instrumental uncertainty. In order to investigate the automated filament winding process, 5 different processing variables are investigated. The experiments aim to study the influence of: 1) The main heat source temperature, 2) The preheating system temperature, 3) The process feed rate, 4) The compaction force and 5) The fiber tension over the consolidation degree of the final parts. The consolidation degree is evaluated through the mechanical properties of the produced specimens. Two different test methods are carried out to characterize the mechanical properties, the cylinder radial compression and the short beam strength test. To double check the mechanical results the void content is also quantified on the specimens. The void content is characterized as follows: First the cylinder’s density is compared with the theoretical composite density at 0% void content. Second the void content of some specimens is calculated analyzing the cross section of the cylinders with an image processing program. Finally the obtained results of the first method are corrected with the more accurate results of the second method. The material used during the experimental investigation is a Twaron – Polyamide 6 commingled yarn. The material I characterized in order to know the relevant properties. It is shown that all the studied parameters have a significant effect on the final cylinders consolidation degree. The best consolidation degree is obtained for a process feed rate between 5 and 20 mm/s, a main heat source temperature between 450-460ᵒC. The compaction force is set to its maximum value 200N and the fiber tension to the minimum value that lets to the proper filament control 4N. Finally the preheating temperature is set to a temperature where the yarn is molten during the travel through it. The mechanical and void content results match with a correlation of 93.47%. The optimal set of process parameters enable to manufacture a cylinder with 94% of interlaminar shear stress of a reference manufactured by compression molding and a difference in the measured void content of 0.1%. The same parameter set has been used to manufacture cylinders of different dimensions and those maintain the consolidation degree.Outgoin