The hand layup of pre-impregnated woven materials is still a large part of the composite manufacturing industry, requiring the skills and experience of a human workforce to form flat plies into complex shapes. It is capable of producing high performance and complex parts, but can be an expensive and variable process. Despite its importance, there appears to have been very little research into the actual methods and techniques used by workers to manipulate flat sheets of composite material into shape during layup. This work presents the first known detailed study of the approach and techniques used by laminators. Four participants laid up onto 15 different shaped molds that replicated features commonly found on composite components. The actions used in layup were grouped into eight distinct techniques. Use of these techniques across tasks of different geometry, ramp angles, radii and drape path was identified using video analysis techniques from the ergonomics field. This revealed strong links between specific features and techniques, revealing a systematic approach to layup. This has enabled the first step toward producing a design for manufacture knowledge base surrounding hand layup. This could then be used to inform the development of the layup process, improve training methods and assist in the design of future automated solutions. Graphical Abstract

Aligned Discontinuous Fibre Composites: A Short History

Leading edge protection (LEP) coating systems are applied to protect turbine blade edges from rain erosion. The performance of a LEP system is assessed in an accelerated rain erosion test (RET) as a metric for industrial application, but these tests are expensive. Modelling methods are available to predict erosion, based on fundamental material properties, but there is a lack of validation. The Springer model (1976) is analysed in this work to assess it as a tool for using material fundamental properties to predict the time to failure in a rain erosion test. It has been applied, referenced and industry validated with important partial considerations. The method has been applied successfully for erosion damage by wear performance prediction when combined with prior material data from rain erosion test (RET), instead of obtaining it directly from fundamental properties measured separately as Springer proposed. The method also offers accurate predictions when coupled with modified numerical parameters obtained from experimental RET testing data. This research aims to understand the differences between the experimental data used by Springer and the current industry approach to rain erosion testing, and to determine how it may introduce inaccuracies into lifetime predictions of current LEP systems, since they are very different to those tested in the historic modelling validation. In this work, a review of the modelling is presented, allowing for the understanding of key issues of its computational implementation and the required experimental material characterisation. Modelling results are discussed for different original application issues and industry-related LEP configuration cases, offering the reader to interpret the limits of the performance prediction when considering the variation in material fundamental properties involved.