A new approach to simulating the draping of prepreg composites manufactured by hand layup

Sammanfattning: Kinematic drape simulations, of applying woven reinforcements to complex geometries, have to date largely focused on characterising the ply shape and the deformations from fitting it to the surface of a mould; amongst other manufacturing management outputs. This is increasingly unsatisfactory: it does not allow for any prediction into the effect of geometry and changes on the layup; does not realistically simulate the draping process as achieved by operators; instruct on the process of how to manipulate a ply to achieve the deformations required, or; enable the information gathered to be exploited in simple useful formats. In essence, drape simulation tools do not allow for 'Design for Manufacturing' and arguably this is inhibiting manufacturing growth. Based on recent activity within ACCIS (University of Bristol), which seeks to develop a Design for Manufacturing in composites solution, this research aims to demonstrate one available route to answer those previous criticisms. It focuses on developing computationally efficient virtual tools that allow for a better understanding of the hand layup of prepreg cloths, as pre- and Post concept routines for existing drape simulation packages. In the Pre-concept tool (conducted before drape simulation takes place), parts can be automatically simulated and reviewed. Risks in quality and difficulty to achieve the design-intent can be assessed virtually by identifying the impact on formability of choices such as ramp angle or pad height. The Post concept routine intends to collaborate with drape simulation outputs. It models techniques and grasps used by professional laminators in terms of in-plane shear deformation and attempts to return the forming process more akin to usual ply handling techniques. This work presents significant advances in the development of the Pre-concept routine, including the application of a knowledge base system to record and exploit drape patterns. However the development of the Post concept routine is by comparison less advanced, due to the modelling of the grip techniques being unable to sufficiently incorporate boundary conditions and mould interactions at this time. Further work involves the completion of this Post concept routine followed by tests in a manufacturing environment.