Studying effects of preshearing on hand layup

Advanced composites are used extensively in many high performance applications. As they are taken up in a wider range of applications, the volume of demand is pushing manufacturing methods, especially hand layup of woven prepreg cloth, to their limits. An alternative approach to hand layup over complex geometries is proposed. The regular method of layup involves generating shear using grasps and pressures in the prepreg as and when it is needed during layup, leading to a sometimes complex and time consuming process. In the method proposed, all the shear deformation is created in the ply prior to any contact between the prepreg and the mold surface. Guidelines were drawn onto the prepreg surface to enable the correct shear distribution to be ‘presheared’ by hand. These were created by processing the outputs from a simple kinematic drape simulation within MATLAB. Once preshearing was completed, the ply is laid up onto the mold using regular hand layup techniques. The process was tested alongside regular manual lamination across three example parts and using video analysis effects of the process were investigated via a variety of metrics. This revealed that significant time savings and reduced likelihood of manufacturing variations are possible with this approach. There was also a significant simplification of the layup process, leading participants to comment that a previously ‘difficult’ layup had become ‘easy’. An improved bespoke system for communicating the required preshearing was subsequently developed, and successfully trialed on a fourth example part. Preshearing has the potential to make hand layup more economically viable for years to come. As well as the productivity and cost benefits, preshearing shows promise as a training aid, especially for beginner laminators. Concepts for integrating preshearing into existing industrial practice and its further potential in the field of automation are also discussed

Intelligent composite layup by the application of low cost tracking and projection technologies

Hand layup is still the dominant forming process for the creation of the widest range of complex geometry and mixed material composite parts. However, this process is still poorly understood and informed, limiting productivity. This paper seeks to address this issue by proposing a novel and low cost system enabling a laminator to be guided in real-time, based on a predetermined instruction set, thus improving the standardisation of produced components. Within this paper the current methodologies are critiqued and future trends are predicted, prior to introducing the required input and outputs, and developing the implemented system. As a demonstrator a U-Shaped component typical of the complex geometry found in many difficult to manufacture composite parts was chosen, and its drapeability assessed by the use of a kinematic drape simulation tool. An experienced laminator's knowledgebase was then used to divide the tool into a finite number of features, with layup conducted by projecting and sequentially highlighting target features while tracking a laminator's hand movements across the ply. The system has been implemented with affordable hardware and demonstrates tangible benefits in comparison to currently employed laser-based systems. It has shown remarkable success to date, with rapid Technology Readiness Level advancement. This is a major stepping stone towards augmenting manual labour, with further benefits including more appropriate automation

Tooling and Infusion Design Strategies to Reduce Trade-Offs in Forming and Infusion Quality of Multi-Textile CFRPs

Achieving right-first-time-manufacture (RFTM) of co-infused textile assemblies is challenging, without improving the accessibility to design knowledge of trade-offs between different tooling and infusion strategies. As demonstrated in previous work, the choice between a flexible or rigid mould material can result in trade-offs between dimensional accuracy and geometrical precision. Similarly, the choice of an infusion strategy can result in trade-offs in infusion quality and time. Building on past work, an investigation into forming variability across the length of six co-infused multi-textile components, with three different tooling inserts and two infusions set-ups, was conducted. To quantitatively assess variation, a method adapting principles of statistical process control was employed to analyse the yarn crimp measured from high-resolution cross-sectional scans of the components. The results were compared to a geometrical and dimensional analysis of the manufactured parts presented in a previous work. The analysis represents a method for capturing forming differences in textile preforms, which can be used to inform designs for the manufacture of textile CFRPs. The results were used to improve a hybrid rigid-flexible tooling design for an infused multi-textile component