Design and Evaluation of a Lightweight Hybrid Wind Turbine Blade

Thesis Abstract

The global wind energy sector faces pressures to reduce production cost and material weight while maintaining structural integrity and reliability under variable loading, prompting a shift toward lightweight, high-performance blade designs. This study addresses the challenge of achieving mechanical robustness and aerodynamic efficiency in wind turbine blades through a lightweight hybrid construction that combines carbon-fiber reinforced polymer (CFRP) and glass-fiber reinforced polymer (GFRP) composites with an optimized core and layup sequence. The aim is to design, implement, and evaluate a novel lightweight hybrid wind turbine blade that delivers enhanced Specific Power (kW/kg) and improved fatigue life without compromising manufacturability or serviceability. The specific objectives are (i) to develop a finite element-based blade optimization framework that couples structural performance with aeroelastic considerations, (ii) to fabricate a scaled 1.5-meter prototype blade using a CFRP/GFRP hybrid layup with an innovative core material and bonding approach, (iii) to validate the prototype under static, modal, and wind-tunnel–simulated dynamic loading, (iv) to assess fatigue performance through accelerated life testing and probabilistic reliability analysis, and (v) to evaluate manufacturing scalability, cost implications, and environmental impact relative to conventional all-GFRP blades. The methodology integrates a mixed-methods approach anchored in design optimization, experimental mechanics, and reliability assessment. The population comprises composite wind blade materials and component subassemblies, with a sample of three blade configurations a baseline all-GFRP blade, a CFRP-skin hybrid blade, and the proposed CFRP/GFRP hybrid blade featuring a optimized core and ply schedule. Data collection instruments include digital image correlation (DIC) systems for full-field strain measurement, dynamic signal acquisition for modal analysis, static loading rigs, rain-wind tunnel testing for aeroelastic response, and accelerated fatigue testing rigs to simulate 20-year operational life within a 6-month protocol. Validity and reliability are addressed through calibration of the DIC system, repeated tests (n=3 per condition), and cross-validation with finite element (FE) predictions. Analytical techniques comprise multi-disciplinary modeling and statistical evaluation. The optimization uses a gradient-based aerodynamic-structural co-simulation that integrates XFOIL-based airfoil performance with FE-structural models in ANSYS, constrained by weight, stiffness, and failure criteria following Failure Modes and Effects Analysis (FMEA). Fatigue life is estimated via S-N curves and Miner’s rule with probabilistic Bayesian updating to account for material variability. Empirical results will be analyzed using analysis of variance (ANOVA) to compare key performance metrics across blade configurations, and regression analysis to identify significant predictors of fatigue life and torsional stiffness. Modal analysis will extract natural frequencies and damping ratios to ensure aeroelastic stability, while reliability analysis will provide reliability indices and sensitivity assessments for critical components. Expected findings include a demonstrable reduction in blade mass by 12–18% relative to the all-GFRP baseline, with a 6–9% improvement in specific energy capture at rated wind speeds due to optimized stiffness distribution and reduced root deflection. The hybrid design is anticipated to exhibit improved fatigue lifetime by 25–40% under variable-amplitude loading, with acceptable increases in manufacturing complexity mitigated by scalable layup sequences and automated fiber placement. The study will identify a cost-to-performance envelope and a strategic manufacturing pathway aligned with environmental and life-cycle considerations. The study contributes knowledge by providing a validated methodology for designing and evaluating lightweight CFRP/GFRP hybrid wind turbine blades, offering a replicable optimization framework, empirical performance data, and a decision-support model for industrial adoption. The main conclusion anticipates that the proposed blade design achieves meaningful weight reduction without compromising safety or durability, enabling higher rotor efficiency and lower Levelized Cost of Energy (LCOE). Recommendations include refining the core material system for higher damage tolerance, exploring alternative resin chemistries to reduce processing temperatures, extending the experimental program to full-scale blades, and developing an integrated manufacturing testbed to support industrial deployment and lifecycle assessment.