Structural design of a composite wind turbine blade using finite element analysis

This paper describes preliminary work to optimise the use of material in a 2.5 m long fibreglass composite wind turbine blade. A program was written to create a detailed finite element mesh of the blade, using design data from blade element theory and panel code predictions, in a format suitable for direct input into a commercially available finite element software package. Finite element predictions compared well with static bending and twisting deflections of the blade and with the first two natural frequencies of vibration. The simulation of a rotating aerodynamically-loaded blade required a nonlinear analysis; the techniques for this analysis and the subsequent predictions are discussed. Different stacking arrangements of the elements from blade element theory to form the final blade shape were considered to minimise both tip deflection and the maximum value of stress for a blade operating at design conditions. The best arrangement aligned elements using a previously developed translation scheme and rotated the elements about their centre of area to the twist angle determined by blade element theory. (C) 1997 Elsevier Science Ltd. All rights reserved.