The evolution of a draping simulation: a) The red areas indicates that with this fabric, a single sheet will not be able to cover the hemisphere without creasing. b) Splits have been added to the fabric, but still it will crease. c) The fabric has been split in two but the fibre orientation is sub optimal. d) The final multi-ply layup
Reinforcement materials for composites, like carbon fibre, come in rolled up sheets yet many composite components are curved. In order to make such components, the reinforcement material must be made to conform to a curved mould surface. For this to happen, the material must undergo some degree of deformation, which is retained in the final part.

Draping describes the manner in which composite fabrics are laid over a mould, and the way that the fibres within the material change in orientation as they conform to the mould geometry.

The way composite materials drape over a curved surface is the single most important factor in defining the manufacturability and performance of composite structures with compound curvature. Aside from simple shapes (tubes, rods, flat panels, etc.) the way that fibres reorient themselves as a result of how they are draped will have the greatest effect on the performance of most composite structures. There is little point in trying to model the performance of such designs without the ability to account for this fact. Even with the highest quality material data and the most sophisticated failure models, it is not possible to realistically model a composite structure unless one can realistically model the orientation of the fibres within it.

Using state of the art software, FAC Technology can predict how such materials will deform over a curved mould surface. Flat patterns can be designed for reinforcement material that will then conform to a mould surface while maintaining a balance between fibre alignment for mechanical performance and layup complexity for manufacturing.

Further, and somewhat uniquely, FAC Technology has developed experimental and  analytical methods to allow for the relative change in the orientation of fibres within textile based composites to be accounted for without the need for vast amounts of experimental testing. These methods enable the properties of elements representing composite materials within a FEA model to be suitably updated to account for this draping effect. To our knowledge, no commercially available software has this capability built in.

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