Cellular materials

Abstract

A structural member comprises a main body formed from a cellular material. The structural member may be a casing for a rotary assembly e.g. a fan of a gas turbine engine. The main body may incorporate strengthening ribs and conduits and may have a random or graduated arrangement of different sized cells forming the cellular material. A recess may be defined on the radially inner face of the main body to receive an abradable material suitable for forming a seal with the blades of the fan.

1 - 27 . (canceled)  
     
     
         28 . A method of forming a structural member characterised by arranging a plurality of beads of a polymeric material in a mould, said beads being of different sizes, applying heat to said beads to at least partially fuse the beads to one another to provide a foam precursor, providing a foamable material on the fused beads to provide a structural member having a main body of a cellular material having cells of different sizes.  
     
     
         29 . A method according to  claim 28  characterised by rotating the mould at least during the step of depositing the metallic or ceramic material.  
     
     
         30 . A method according to  claim 28  characterised in that the beads of the polymeric material are randomly arranged in the mould to provide a structural member having a main body in which the different sized cells are randomly arranged in the main body.  
     
     
         31 . A method according to  claim 28  characterised in that the beads of the polymeric material are arranged in a graduated array in the mould to provide a structural member having a main body in which the different sized cells are arranged in a graduated array in the main body.  
     
     
         32 . A method according to  claim 28  characterised in that said foamable material is provided by deposition on the fused beads.  
     
     
         33 . A method according to  claim 32  characterised in that the deposited material is deposited on the foam precursor by vapour phase deposition or electrolytic deposition.  
     
     
         34 . A method according to  claim 28  characterised in that said foamable material is provided by being grown on the fused beads.  
     
     
         35 . A method according to  claim 34  characterised in that said foamable material is chemically grown on the fused beads.  
     
     
         36 . A method according to  claim 33  characterised in that the foam precursor is removed by burning off, chemically removing or dissolving said foam precursor.  
     
     
         37 . A method according to  claim 28  characterised in that the foamable material is a metallic or ceramic material.  
     
     
         38 . A rotary assembly fro a gas turbine engine comprising rotary components and a structural member comprising a main body, a further body and means for mounting the structural member on around the further member characterised in that the main body is formed from a cellular material with the structural member surrounding the rotary components.  
     
     
         39 . A gas turbine engine incorporating a rotary assembly as claimed in  claim 38.