What Would Be The Optimal Fiber Orientation And Volume Fraction Of A Hybrid Carbon-glass Fiber Reinforced Polymer Composite To Achieve A Balance Between Tensile Strength And Interlaminar Shear Strength, While Minimizing The Risk Of Delamination Under Cyclic Loading Conditions, Specifically For A Wind Turbine Blade Application?

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To determine the optimal fiber orientation and volume fraction for a hybrid carbon-glass fiber reinforced polymer composite for wind turbine blades, the following approach is recommended:

  1. Fiber Selection and Volume Fraction:

    • Carbon Fibers: Utilize for their high tensile strength and stiffness, particularly in load-bearing areas. A volume fraction of 50-60% is suggested to enhance tensile properties without excessive brittleness.
    • Glass Fibers: Incorporate for toughness and cost-effectiveness, with a volume fraction of 40-50%. They improve interlaminar shear strength and delamination resistance.

  2. Fiber Orientation:

    • Unidirectional (UD) Layers: Use primarily along the blade's longitudinal axis (0°) for maximum tensile strength.
    • Woven Fabrics: Incorporate ±45° layers to enhance interlaminar shear strength and delamination resistance.
    • Hybrid Layup: Combine UD carbon for tensile strength with woven glass for toughness, ensuring a balanced structure.

  3. Laminate Design:

    • Skin-Core Construction: Use UD carbon in the outer skin layers for tensile performance and woven glass in the core for interlaminar properties.
    • Symmetric Stacking: Ensure symmetric layer stacking to prevent warpage and maintain structural integrity.

  4. Material Interfaces:

    • Apply compatible coupling agents or sizing to improve carbon-glass fiber bonding, reducing delamination risks.

  5. Testing and Validation:

    • Conduct tensile, short beam shear, and fatigue tests to assess mechanical properties under cyclic loading.
    • Evaluate mode I and II fracture toughness for delamination resistance.

  6. Manufacturing Considerations:

    • Opt for automated processes like Resin Transfer Molding (RTM) for precise fiber placement and control.

In conclusion, a hybrid composite with 50-60% carbon and 40-50% glass fibers, combining UD and woven layers at strategic angles, offers a balanced approach for wind turbine blades, optimizing tensile strength, interlaminar shear strength, and delamination resistance under cyclic conditions.