Simulation of Wrinkling during Forming of Binder Stabilized UD-NCF Preforms in Wind Turbine Blade Manufacturing

Abstract

Binder stabilized preforms are getting increased attention in the wind turbine industry with the aim to increase automation in the production of large blades. In this context a preform is a stack of dry unidirectional glass fiber non-crimp fabrics (UD-NCF), which is consolidated using a polymeric binder. The preform is manufactured in a separate mold, and subsequently placed in the main blade mold. During placement of preforms, fiber wrinkling may occur due to the deformation of the preform. To accommodate this problem, we propose a predictive simulation model that can be used to investigate how different process parameters influence the wrinkle creation. Most forming simulation models in the literature consider frictional laws in the inter-ply interface for multi-layered fabrics. In this work the binder interfaces between the layers are modelled using a cohesive traction-separation law to accurately model binder degradation and wrinkle creation during preform deformation. The model predictions are compared with full thickness preform coupon specimens.