The Internal Stress Evaluation of Pultruded Blades for a Darrieus Wind Turbine

This paper investigates the integrated modeling of a pultruded NACA0018 blade profile which is a part of the FP7 EU project Deep Wind. The pultrusion process simulation is combined with the preliminary subsequent in-service load scenario. In particular, the process induced residual stresses and distortions are predicted by using a new approach combining a 3D Eulerian thermochemical analysis, in which the temperature and the cure degree distributions are obtained, and a 2D quasi-static plane strain mechanical analysis. The post-die region where convective cooling prevails is also included in the process model. The bending into shape of the pultruded blade profile is simulated with and without taking the residual stresses into account. The internal stress distribution in the profile is evaluated after the bending analysis and it is found that the process induced residual stresses have the potential to promote or to demote the internal stresses in the structural analysis.