Abstract

With the aim of improving composites manufacturing process costs and properties, in order to compete with others materials, a new process of impregnation, compaction and curing of fibre glass reinforcing composites, has been developed. This new process based on UV curing prepregs could be an alternative to the traditional manufacturing process, including infusion process and autoclave curing.

These new process consists of two stages. First, the automated manufacturing of the UV curing prepregs. Second, the compaction of the composite by means of application of pressure and UV radiation giving rise to the finished part.

In this work, the UV prepregs manufacturing process will be analysed, and the effect of the control parameters of the all process, composed by impregnation, resin content adjustment and precuring, will be analysed. The durability of different manufactured UV prepregs and the mechanical behaviour of the resulted composite will be also studied. Finally, the prototypes necessary to the automation of the two stages of the process will be described.

Abstract

This study aim at understanding the void formation, transport mechanisms and porosity evolution during OoA consolidation process. The laminates were conformed by stacking and compacting of prepregs by two different technologies: manual (Hand lay-up, HLU) and automatic (Automated fiber placement, AFP). Subsequently the laminates were cured by the vacuum bag only (VBO) technique in an industrial oven at atmospheric pressure. The porosity characterization was performed using ultrasound and x-ray tomography technologies at different stages of the cure cycle. Ultrasonic inspections showed that the porosity is heterogeneously distributed, where the higher volumetric fraction of pores is located in the center of the laminate. X-ray tomography provided three-dimensional (3D) information of samples of the laminates and it allowed a quantitative and qualitative study of the pores within the tows of fibers and the porosity located between the layers of prepregs during the curing process. The prepregs designed for out of autoclave are partially impregnated in such a way to provide air evacuation channels in the fiber tows. The porosity of these channels was efficiently extracted and a volumetric fraction of pores entrapped between layers were evacuated during the curing process. The behavior of the evacuation channels and the porosity evolution for both stacking technologies were compared. An analytical model of the evolution of a pore was also developed.