TRIAXIAL FABRIC

TRIAXIAL FABRIC

ABSTRACT

Optimum stitching for triaxial or multilayered fabric can be determined for the optimum handleability and the extended life service of a composite utilizing this type of reinforcement.

The use of non-crimp fabrics (NCF) is well known in both the fabrics and the composite materials industry.  Such fabrics may be woven or they may be what are commonly referred to as being “stitched”.   Stitching is usually referred to as the use of tricot or chain stitch patterns. This stitching, sewing or binding of fibers combines three or more layers of reinforcement yarns into a unit which is handleable and which may be used as produced or as an impregnated   product.  The three dimensional or triaxial fabric thus can consist of individual layers of single strand reinforcements which can be placed in different layered orientations to achieve the best drape or handleability characteristics consistent with the placement of the strength vectors in the desired orientation.  A typical triaxially stitched fabric may contain a layer of +45° offset to the parallel direction of the fabric length (linear dimension), a -45° layer offset to the parallel direction of the fabric length and a 0° layer which is the pillar or the referenced (linear) parallel direction.    

 These NCF fabrics prove to be highly advantageous in that the crimp or waviness of congenitally woven multiaxial yarns passing over and under one another is eliminated   in comparative fabrics of the same weight. This lack of crimp contributes significantly to the strength and length of service of the triaxial material.  This is primarily due to the reduction of the number of abrasion areas at yarn cross over points.

Stitching of multiaxial fabrics composed of non-woven layers of reinforcement is usually accomplished using a tricot, chain stitch or other configurations known to those skilled in the art.   Often, thermoplastic yarns are used as the stitching materials such as polyethylene, polypropylene, nylon and the like while the yarn composition is not limited to this class of materials.  The number of stitches or gauge required to bind the layers together is mostly a function of handleability and the number of stitches necessary to retain the layered components in a uniform configuration.  Cost is also sometimes a significant factor.  Stitching patterns used to hold fibers together in a triaxi...