JEC COMPOSITES MAGAZINE - Issue #49 - June 2009 - 38

FEATURE “Wind Energy” All three hybrids reached a similar level of properties indicating that the Devold stitch and functional aid technology combined with Tenax STS fibre achieved improved flow properties with no loss of mechanical performance. Normalizing the properties based on the 0° fibre content gave an additional approximation of how well the carbon fibre capability is utilized in the hybrid NCFs, as shown in Figure 5. The carbon fibre ply with an elastic modulus of more than 300% and a compression strength of approximate 115% of the reference glass ply confirmed good translation behaviour of the employed fibre. Further improvements are feasible, particularly in terms of compression strength. g…/… New composite hybrid reinforcements for the wind turbine industry Devold’s proprietary stitching technology. The resulting permeability was four times higher than with the glass material, allowing for a much more rapid, quality infusion. Fig. 3: Transverse permeability KDz (through-thickness direction). Mechanical properties The critical mechanical properties for composite materials in windmill blades are fatigue and stiffness. Carbon fibre exhibits stiffness, strength and fatigue properties that are substantially higher than those of glass fibres. For instance, the modulus of the Tenax STS40 carbon fibre can be up to 3½ times higher than for a standard E-glass fibre. However, the challenge has been to translate these preferred properties into accountable composite properties, in particular for infusion-based composites. Critical factors such as fibre alignment, resin and void content control require specific solutions for VARTM processed composites. The developed hybrids show an excellent translation of fibre tensile properties, as depicted in Figure 4. Even though the relative amount of 0° directed fibre was 55% vs. 78% for the hybrid and the reference respectively, the hybrid-based laminates achieved approximately twice the modulus and strength values. Fig. 5: Normalised 0°-ply properties (test direction: 0°). Conclusion The studied carbon-/glass-fibre hybrid materials produced using Devold’s multiaxial weft insertion process and Tenax STS fibres combine the ease of glass fibre processing with the performance of carbon fibre-based NCFs. Devold’s proprietary textile stitching technology and functional flow aid largely improve infusion characteristics compared with standard glass solutions with no loss of mechanical properties. Hybrid NCFs provide a very interesting way of achieving large weight savings in stiffness/fatigue driven applications while helping to reduce processing times through high permeability and reduced ply counts. More information: www.amt.no Don’t wait! Apply for your FREE subscription on Fig. 4: Tensile laminate properties according to ISO 527 (test direction: 0°). www.jeccomposites.com/magazine-subscription 38 jec composites magazine / No49 June 2009

http://www.amt.no http://www.jeccomposites.com/magazine-subscription http://www.jeccomposites.com/magazine-subscription

JEC COMPOSITES MAGAZINE - Issue #49 - June 2009

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #49 - June 2009