Structural design and analysis of a small wind turbine blade using Simple Load Model, FAST-MLife codes, and ANSYS nCode DesignLife

Abstract

This article presents a structural design and analysis of 11-kW small wind blades. The stress and the fatigue on the blades were computed using Simple Load Model from IEC 61400-2 standard, ANSYS nCode DesignLife, and FAST-MLife codes from the National Renewable Energy Laboratory. Simple Load Model gives good results in terms of stress analysis but overestimates fatigue damage on the blade. High safety factors imposed by the IEC 61400-2 standard, when full mechanical characterization of the blade material cannot be achieved, lead to heavy structures that impact the blade cost. For the same design, full computational analysis of the blade fatigue using FAST-MLife codes and the ANSYS nCode DesignLife revealed that the rotor blades will be safe against fatigue for a design lifetime of 20 years. This study shows that simple and reliable aeroelastic models are still needed for fatigue analysis of small wind blades.