MANUFACTURE OF COMPRESSOR ROTOR BLADES AND OTHER STRUCTURES RESISTANT TO FOREIGN OBJECT DAMAGE

摘要

1414146 Laminates GENERAL ELECTRIC CO 20 Oct 1972 48413/72 Heading B5N [Also in Divisions F1 B3 B7 and C7] A structure resistant to foreign object damage, e.g. a radome, compressor blade or strut, comprises a wire mesh overlying and bonded to a core structure by a bonding agent substantially filling the interstices of the mesh, the latter itself being overlaid by a metal cladding. In one arrangement, Fig. 5, a compressor rotor blade comprises a core 15 of elongated graphite fibres embedded in a resin matrix. A stainless steel wire mesh layer 20 is wrapped around the leading edge of the core 15 and bonded thereto by resin which fills the interstices of the mesh. The latter is overlaid by nickel cladding 22. Additional wire mesh layers 24 may be embedded in the core matrix. The blade is constructed by forming sheets 18, Fig. 1, of parallel graphite fibres embedded in a resin matrix as well as sheets 26 of stainless steel mesh 24 in a similar matrix. Sheets 26 may additionally include loosely woven cloths of glass fibre (30, Fig. 9, not shown). The sheets 18, 26 are then cut to shape and stacked together with the fibres of adjacent sheets 18 angled with respect to each other and the wires of mesh 24 inclined at 45 degrees to the sheet edges. The assembly is cured in a mould to form a laminated structure, the mesh layer 20 either being incorporated during moulding or applied thereafter. In the latter case mesh layer 20 is wrapped round the moulded blade, coated with a bonding agent such as epoxy resin filled with aluminium and then cured under heat and pressure. The nickel cladding 22 may alternatively be applied by electroplating in such a way that the nickel layer has a thickness of 0À025 inch at the leading edge tapering to about 0À005 inch at the trailing edge of the mesh. The resulting step at the latter region is filled by cured polyurethane 100 faired into the aerofoil shape. In a modification (Fig. 6, not shown) a recess is cut in the blade surface to receive the mesh and cladding layers 20, 22 so that no fairing material is required. In a further modification (Fig. 12, not shown) the subsurface mesh layer (20SP1/SP) is formed into a point at the blade leading edge rather than being smoothly rounded. In other arrangements, boron, silicon carbide or alumina filaments may be substituted for the graphite, the matrix material may be aluminium and the wire mesh titanium. Dimensions of the wires fibres &c. are quoted.