Multidirectional Filament Reinforced Tape and Method of Manufacture

Abstract

The apparatus is a laminar shear resistant pre-impregnated resin tape for use in die forming pultrusuion processes, with the tape formed by integrating three distinguishable layers, each with integrated parallel reinforcing filaments. The layers are arranged within the tape so that the filaments of adjacent layers are oriented at angles to each other. The tape of the preferred embodiment of the invention is constructed with the filaments of the center layer at 90 degrees to the length of the tape and the filaments of the two outer layers aligned with the length of the tape. The center layer can be more heavily loaded with filaments than conventional tapes, and the outer two layers have less than the amount of filament load of the center layer.

Description

BACKGROUND OF THE INVENTION[0001]This invention deals generally with filament reinforced thermoplastic pre-impregnated tape, and more specifically with a multiple directional and multiple layer filament reinforced thermoplastic tape for use in pultrusion processes.[0002]Mixtures of various filaments and plastic resins are used to produce composites that have unique properties compared to the traditional engineering materials like metals and non-reinforced plastics. The filaments in the resin matrix increase the strength of the composites so much that they far exceed even the strongest metals, although composites are much lighter than their metal counterparts.[0003]Thermoplastic resins are often used to make these composites. Thermoplastic resins are solid at room temperature, and they soften and ultimately melt at elevated temperatures turning into a very viscous liquid. Reinforced thermoplastic composites are typically produced by intermingling finely ground resin particles with bu...

AI Technical Summary

Benefits of technology

The present invention provides a prepreg tape that solves many of the problems of prior art products. The tape has a unique design with three layers of filaments and resin that are fully bonded together, creating a single layer tape that looks and acts like a single layer tape. The tape also has a balanced design that allows for increased efficiency of filament usage and increased strength of the final product. The tape can be used in a pultrusion process without the need for a separate spot welding attachment process. The tape also has a high filament loading and low resin content, which prevents failure in the final product. The tape can be used as the outer layer of a composite part, providing better protection against resin fouling and resulting in a stronger final product.

Problems solved by technology

This process is labor intensive and less than ideal.

If a piece is absent in the composite, the finished product is defective.

The resulting composite is inefficient because the 50% of the filament oriented in the lengthwise direction is not used to carry the bending load across the width direction.

Another problem is that the alternating layers of 0 and 90 degree filaments must be arranged to achieve a balanced design.

However, using the two layer tapes, an operator error is easily possible.

This results in a product flaw.

Components made using a 0 and 90 degree prepreg orientation can also exhibit shear failures when subjected to bending.

This failure mode is most prevalent in products made from prepreg that has high filament loading and low resin content.

These failures typically occur at the interface between the 0 and 90 degree layers at the center of the bending plane; but usually never within a composite layer itself.

This shear failure condition can limit the ultimate strength of the part.

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