JEC COMPOSITES MAGAZINE - Issue #71 - March 2012 - 94

bi-angle NCF

Fig.2: Bend/Twist coupling using hybrid Bi-angle NCF [Prof Sung Ha, Hanyang University]

Wind turbines blades applications
Hybridization of composite materials can certainly provide blades composite designers with more design freedom, enabling lower weight; while meeting the strength and stiffness requirements at acceptable costs [Prof Sung Ha, Hanyang University]. Some new advanced NCF has also been tested to introduce this revolutionary design in wind turbine blades. To increase the bend twist coupling effect of the material, different hybrid material forms can be used, in terms of weight of material in each direction, degree of angles, and fibers combinations, for example carbon / glass fiber. Current composite design practices are in most cases limited to conventional rules and lay-up sequences: unidirectional laminates (UD), bi-axial (±45) and triaxial [02/±45]S laminates, allowing only thickness variation. The highest strength and stiffness in the longitudinal direction are reduced as the off-axis angle increases. But the in-plane shear strength increases as the off-axis angle increases. if the conventional fibre angle 45 degrees is changed to a 25-degree fibre angle, the effective stiffness and strength of a triaxial NCF laminate are 25% and 2 times higher respectively, Tab.2: Advanced NCF possibilities whereas the shear strength decreases by only 5% [Prof. Sung Ha, Hanyang University] .
Fig.3: Anisotropy and hybrid NCFs tip deflection evolution versus m6 (torsion moment) (datas from Prof. Stephen W. Tsai, Stanford University)

parts (fig. 3): - using C-PLY™ Bi-Angle compare to orthotropic ( plain line versus dashed). - using C-PLY™ Bi-Angle (0/25) compare to (0/45) - using CG-PLY™ Bi-Angle hybrid Glass / Carbon

Conclusions
Testing programs with C-PLY™ Bi-Angle are in progress with interesting results using RTM, prepreg and tape laying technologies. The JEC 2012 design conference will present the results of many of those studies. New opportunities with Advanced NCF look promising and will be under evaluation in the next few month. We are summarizing the Chomarat range mixing the raw materials possibilities (blue) and the NCF construction (green), table2. n
More information: www.chomarat.com

Aeronautics FuseFan lage blades
x x

Wing
x

Automotive

Wind blades

Tubes /shaft
x

Pipes

Hybrid anisotrop NCF composites properties

Another example of the design possibility (Bend / Twist couMedium plies 130/250g/m2 pling Carbon/Glass CG-PLY™ (carbon 12/24/50k) Bi-Angle) is shown in figure 2. The Thick plies >300g/m2 maximum twist angle is achieved (carbon 24/50k and GF) at 25° of a CG-PLY™ Bi-Angle. Mic Mac tools study is also Fully equilibrated showing the interest of anisotroBi-Angle or optimized angles pic and hybrid (Advantex Glass and Carbon T700) CG-PLY™ Orthotropic shallow angle Bi-Angle, Designers could decrease UD tip deflection of the composite

Thin plies 50/75g/m2 (carbon 12k HR, IM)

x x x x x tbd x x

x x x

94 jec composites magazine / No71 March 2012

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JEC COMPOSITES MAGAZINE - Issue #71 - March 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #71 - March 2012