Towards real-time manipulation of virtual fabric reinforcement - extending and enhancing kinematic drape simulation tools

Often the efficiency of continuous fibre composite components is determined by the effectiveness of the link between design and manufacture. Simulation tools are used in the design phase to optimise components as well as to provide a design / manufacture feedback loop that identifies manufacturability limitations. Complex shaped aerospace components are usually manufactured either with automated fibre placement machinery or by manual lay-up processes, as these are often the only manufacturing methods that can provide the degree of dexterity required to manipulate the reinforcement to form complex shapes. If drape simulation tools are to provide a design / manufacture feedback loop for components made through manual lay-up processes, they must incorporate the range of manipulations available and limitations present in the manual lay-up environment. Kinematic drape simulation tools are widely used in the design of bi-directional fibre reinforced composite components and are particularly useful in understanding the manual lay-up draping process. They provide a quick first approximation as to whether a shape is formable or not and if so, the likely tow trajectories. However, currently the range of theoretically formable shapes differs from those that are practically formable. The current paper suggests a strategy by which the design / manufacture feedback loop provided by kinematic drape simulation can be enhanced to remove this difference. The strategy presented interprets both the simulation input and draped solution in terms of hand lay-up manufacturing principles and suggests how prescriptive manufacturing instructions can be produced. These instructions guide the practical lay-up to the intended tow trajectories rather than just presenting a final tow pattern for a preform. Kinematic drape simulation tools at present only predict wrinkling due to excessive in-plane shear of the fabric in a preform. In addition to generating manufacturing instructions the current strategy suggests how kinematic simulation tools can be enhanced to identify a wider range of potential defects such as in-plane and out-of-plane tow wrinkling in bi-directional fibre preforms. The strategy outlined is implemented in a kinematic simulation model and the results from practical drape experiments on a range of complex shapes are presented to verify both the manufacturing guidelines generated by the simulation model and its method of defect prediction.