Process Simulations for Composites Forming of UD Tape

Thermoplastic composites are widely recognized for their high specific stiffness, strength and toughness, in combination with the opportunities for rapid processing and recycling. Experience has learnt that composites should not be treated as black metal, amongst others due to their spe-cific deformation behavior during processing. Certain aspects are well known: a low shear re-sistance in fabric reinforced composites, high stiffness in the fiber directions, and a low resistance to extension transverse to the fibers in unidirectional plies. Other aspects are less well known and less well characterized yet, e.g. the frictional behavior between plies and between laminates and tools, and the bending behavior of composite laminates at forming temperatures. Novel develop-ments in unidirectional laminate production pave the way for more optimized pre-forms (near net shaped with e.g. local reinforcement) for subsequent press forming. Design and processing with such tailored laminates involves complexities on the level of the separate plies and their interac-tions, but also on the level of the laminate as a whole, in terms of lay-up which can vary in orienta-tion and thickness, and which can change during the forming process. Process simulations can help to improve control on the design and manufacturing development of thermoplastic composite products. Adequate process simulation tools are currently under development. Constitutive models of unidirectional plies and laminates still require considerable development, certainly when compar-ing to fabric reinforced composites, including characterization experiments and implementation in nonlinear finite element software. The methods are validated with press-forming experiments