Friction in composites forming

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A wide range of forming techniques have been developed for composites. There is a correspondingly large number of composite materials available, e.g. dry material or material pre-impregnated with resin, while the textile architecture can take many forms such as unidirectional or woven. A key motivation for introduction of these processes is increased automation, giving reduced cycle time and cost and increased repeatability and quality. However the development of the appropriate material and process for a given application has often proved problematic, with process development being a costly, empirical activity with a rather uncertain chance of success. The goal of this project is to gain a fundamental scientific understanding of friction in composites forming, to develop standard tests which capture the appropriate mechanisms, and to demonstrate how these tests and models can be applied to manufacture of a case-study component. The value of the research will be demonstrated by application of the experiments and modelling to the case study component to quantify potential improvements in product quality.Uni-directional and woven carbon will be used in dry form and as pre-prepreg. Friction between the tool or vacuum bag and the composite and between plies will be considered. Processing routes that will be explored will be a consolidation-type of deformation and a draping-type of deformation. In both cases idealised forms of geometry will first be used to gain the underlying scientific understanding. Observations of the contact conditions in laboratory-scale tests will be used to uncover the mechanisms leading to friction in composites forming. Tribological models of the contact between the various elements (tool to ply and ply to ply) will be developed and validated via tribological lab experiments. Standardised tests will developed to measure friction in a way that replicates the mechanisms found in the tribological tests. A case study geometry will be used to understand the implications for forming of components. The work will be in close collaboration with the industrial partners who will assist with supply of materials, definition of appropriate tests methods and help with the case study formulation and implementation.