Design for Pultrusion of braided fabric Reinforced Thermoplastic Composite Tube

摘要

Pultrusion process is one of the composite production methods that have been used for mass production of uniform profiles. However, there are two problems that are commonly found in pultrusion products; one of which is its anisotropic mechanical properties. This anisotropicity stems from the alignment of reinforcements in the longitudinal direction during the pultrusion process. The other problem is the difficulty in recycling since thermosetting resins are typically used as the matrix resin for these composites. Therefore, a combination of braiding and pultrusion techniques as well as the usage of thermoplastic resins to produce continuous fiber reinforced thermoplastic composite profiles is proposed in this study. Instead of using comingled yarns, an intermediate braided material was produced by a method known as micro-braiding where resin fibers were braided around the reinforcement. These fiber bundles were then fed through a larger braiding machine where they were continuously oriented in an oblique direction according to the desired fiber orientation angle to produce tubular braided fabrics. When an FRP pultruded tube is fabricated with the tubular braided fabric, good dimensional accuracy especially in terms of circumference as well as the cross sectional area should be maintained. Therefore, the fill ratio, which is the ratio of the tube cross sectional area to the area of the pultrusion die, was determined in this study. A design methodology that could predict the circumference and fill ratio of the tubes was proposed while considering the structural parameters of braided fabrics. The accuracy of this design methodology was then confirmed through actual production of the tubular braided composites.