A hyperelastic approach for modeling the membrane behavior in finite element forming simulation of unidirectional non-crimp fabrics (UD-NCF)

Unidirectional non-crimp fabrics (UD-NCFs) are highly suitable for high-performance components due to their excellent lightweight potential. However, during forming they are prone to wrinkling and gapping compared to woven or biaxial textiles. Macroscopic simulation models can be used to efficiently predict these effects as well as the global forming behavior for complex geometries. Therefore, a new hyperelastic membrane model is proposed to describe the typical deformation of UD-NCFs based on superimposed shear, transverse tension and compression perpendicular to the fiber rovings. The model is parameterized using the forces and different ratios of superimposed strains obtained in experimental off-axis-tension-tests at bias angles of 30°, 45°and 60°. The resulting approach is validated by forming simulations of a hemisphere and tetrahedron geometry in different configurations and quantitative comparison to experimental tests. The model accurately predicts the forming behavior of UD-NCF with a good agreement of the global deformation behavior and local strains.