Investigation of the Membrane Behavior of UD-NCF in Macroscopic Forming Simulations

Unidirectional non-crimp fabrics (UD-NCF) provide an exceptionally high lightweight potentialcompared to other dry fabrics. However, their defect-free formability is limited compared towoven or biaxial fabrics due to their susceptibility to draping effects like wrinkling, gapping andfiber waviness. To predict these local effects and the global forming behavior efficiently, macroscopicmodelling approaches require the consideration of the mesoscopic material structure. A very detailedmacroscopic approach was proposed by Schirmaier et al. [1] and its prediction accuracy validatedwith qualitative and quantitative comparisons to component forming results. However, the approachcouples several deformation modes and therefore requires a very high number of inversely determinedmaterial parameters. In the present work a new macroscopic forming model for the membrane behaviorof UD-NCF is introduced based on superimposed shear, transverse tensile and perpendicular to thecarbon fiber tows oriented compressive strains. The model is parametrized with experimental resultsof different off-axis-tension-tests (OATs) (30°, 45° and 60°) and compared to the model proposed bySchirmaier et al. [1]. The results of the new membrane model agree well with the experimental andsimulative results in large areas, while utilizing a significantly reduced number of material parameters.However, some limitations are identified due to the reduced complexity of the model.