Efficient numerical analysis of in-plane compression-induced defects in thick multi-ply woven textile preforms during double diaphragm forming

To gain adoption in the composites manufacturing sector, forming process models must be assessed for their suitability in analysing representative preform architectures processed in industrial production environments. A computationally efficient, mutually constrained Shell-Membrane (S-M) finite element approach is developed to predict the anisotropic, non-linear deformation of a woven textile preform in a Double Diaphragm Forming (DDF) process. Formability of a thick, multi-ply aerostructures preform is numerically investigated and experimentally correlated using a high-volume, industrial forming process. The effects of fibre orientation, preform thickness, and inter-ply friction on defect formation are investigated. The process model identifies in-plane axial fibre compression as the primary mechanism leading to macroscopic buckling defects and infers the underlying defect morphology. Defect formation is shown to be weakly correlated with the state of the fabric shear strain field. The study concludes that buckling defects are mitigated by reducing tangential contact friction between preform plies.