NEW SOLUTIONS IN THE PRODUCTION OF COMPOSITES - MECHANICAL PROPERTIES OF COMPOSITES REINFORCED WITH TECHNICAL EMBROIDERY AND WOVEN FABRIC MADE OF FLAX FIBERS

The main purpose of the article is to present the new possibilities of producing natural fiber composite reinforcement. In this case, a computer embroidery machine by ZSK type JCZA 0109-550 was used. A technical embroidery with a stitch length of 2 mm was made on the machine. The embroidery was made of flax roving with a linear density of 400 tex. The woven fabric was made of the same flax roving as the embroidery, with a surface mass of 400 g/m2. Composites were then produced from the technical embroidery and woven fabric using the infusion method with epoxy resin. The individual configurations differed from each other in the orientation of the roving in the embroidery samples. Samples for tensile strength and tensile elongation tests consisted of 4 layers, while samples for the DCB test consisted of 6 layers, with the addition of a separating foil between the 3rd and 4th layer. Composites were then subjected to strength tests - tensile strength, tensile elongation and DCB test (Double Cantilever Beam test), on the INSTRON machine. During the action of force along the direction of the fibers, composites containing technical embroidery as reinforcement were characterized by higher strength than composites containing woven fabric as reinforcement. Additionally, embroidery is a barrier to the formation of interlayer cracks. Technical embroidery is made on the basis of Tailored Fiber Placement (TFP) technology. This technology allows optimizing the mechanical values of the composite reinforcement.