Title: CONTINUOUS-LENGTH +/-45 SPREAD TOW FABRICS REDUCING KNOCKDOWN FACTOR FOR BIAS REINFORCEMENTS
Abstract: Spread Tow fabrics have already proven to offer reduced weight, increased stiffness and strength, improved impact as well as better dampening performance of composites parts and can be highly tailored to meet specific needs. By offering continuous length +/- 45 fabrics in up to 60” (1524mm) width, the construction freedom is highly broadened. Thinner ply layup is possible to utilize as the transition from handling, sometimes flimsy, thin UD plies in bias angles to stable and symmetrically balanced +/-45 fabrics, allow for full handle ability and reduced number of plies needed. The material presents a +/-45 ply with truly the same properties in +45 and -45. Also, the need for splicing and joints generating thickness variations at large parts and the economically important labor saving and reduced scrap material level associated with bias cutting edge triangle waste are eliminated compared to use of traditional 0/90 and UD reinforcements. Furthermore, the +/-45 Spread Tow fabric is stable to handle and to prepreg in normal hot melt lines without skewing. More important, Spread Tow +/-45 does not include any stitching or fixation yarn. This minimizes the risk of mechanical issues such as micro cracks but also the difficulty in predicting its mechanical performance due to the induced geometrical variation the stitching or stabilizing/fixation yarns normally give in the meso structure.
Authors: Fredrik Ohlsson
Conference: CAMX 2017 –Orlando