Consolidation of locally reinforced composite shafts using multiscale modelling

A multiscale approach is presented for the process modelling of locally reinforced metal matrix composite (MMC) shaft components. Micromechanical models are first developed for both hexagonal- and square-packed titanium alloy foil-SiC fibre-foil (FFF) composite materials, which are used to investigate the dependence of densification on pressure. The possible use of titanium alloy matrix coated fibres (MCFs) within the FFF consolidation process is also investigated, and it is shown that densification rates are considerably higher. The F-MCF-F processing route also offers the advantage of careful control of fibre spacing and the reduced likelihood of fibre damage during processing. The densification results obtained at the microlevel are used to develop homogenized porous plasticity constitutive equations for the densification of the composite which are implemented within finite element software. Analyses of component processing then become possible, and the processing of a locally reinforced shaft is investigated. It is shown that higher processing rates are achievable using hexagonal packing, and that, during processing, a radial variation in relative density exists until full densification is achieved in the composite-reinforced region of the shaft. The combinations of loading rate and fibre array type giving rise to full densification during processing are investigated.