Thermo-ductile composites: new materials for 21st century manufacturing—micro-perforation symmetry

New thermo-ductile composite materials with highly aligned discontinuous fibre reinforcement are being developed for the manufacture of light weight structural parts. Their enhanced formability and high specific stiffness make them interesting candidates for metal substitution in the cost effective volume manufacturing of lightweight structural parts. These new discontinuous fibre materials are produced by laser micro-perforation of pre-impregnated unidirectional composite precursors. The process converts the composite into a mass of small aggregates made up of aligned discontinuous fibres, otherwise called fibre domains, which become the key micro-structural participants in subsequent deformation processes. Micro-perforation is an inherently flexible process, which can convert a single composite precursor into a wide range of products. The treatment may be overall or only applied to those parts of the structure that need to exhibit enhanced formability. The induced fibre length may be consistent throughout the material or may be varied between different parts of the structure. In this paper the symmetry considerations underlying the selection of the micro-perforation patterns are discussed.