Power plants – Reaction motor – Interrelated reaction motors
Patent
1992-02-28
1994-05-31
Bertsch, Richard A.
Power plants
Reaction motor
Interrelated reaction motors
428116, 428256, F02K 302
Patent
active
053158202
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to composite structural components and is particularly although not exclusively concerned with composite structural components for use in a fan jet aero engine nacelle environment, where noise suppression, fatigue and vibration are important factors that have to be considered in the design of the nacelle structure.
To counteract excessive noise emanating from high speed gas flows or from the fan itself in fan jet engines, it has been proposed to embody, at certain locations on an engine nacelle, structural panels which are capable of partially absorbing the sound energy generated by such flows or by the engine or auxillary mechanisms; for example at the inlet cowl, on the fan duct itself and on the thrust reverser translating cowl.
Numerous types of such panels have been proposed but usually present a common feature of having a structure consisting of an outer porous sheet in contact with the gas flows, a single or multiple porous septum separated intermediate layer of cellular form, for example honeycomb form, and a rear closing sheet.
In previously published prior proposals, the outer porous sheet has taken the form of (i) a metal or composite perforate sheet, (ii) multiple layers of glass fabric, or (iii) a large mesh carbon fibre fabric.
Fatigue, the phenomenon of structural or system failure, caused by repeated excitations from high frequency noise or vibration levels, can occur without warning in inlet cowls, fans ducts and thrust reverser translating cowls.
Inlet cowls suffer primarily from acoustic fatigue emanating from high frequency excitations from the engine fan tips rotating at high speed.
Fan ducts in the region of blocker door drag link pickups of a thrust reversal unit, suffer acoustic and structural fatigue from excitations from the cold high speed fan stream.
Thrust reverser translating cowls suffer acoustic, structural and systems fatigue from excitations from the cold high speed fan stream coupled with vibrations induced from high cycle thrust reverser utilization.
On engine nacelles manufactured from metal in the areas described, fatigue manifests itself in the form of a crack or break in the structure. On nacelles manufactured from glass fabric, aramids or carbon fibre, fatigue manifests itself in the form of delamination, disbonds or interlaminar cracking.
On modern day nacelle and fan duct design, the use of composite structures predominates and it is an object of the present invention to provide a composite structural component which does not suffer or does not suffer to the same extent from the above described potential fatigue problems.
According to a first aspect of the present invention there is provided a structural component having a front face for exposure to fatigue generating energy, the component including a composite frontal region which includes the front face and which comprises a matrix and a high fatigue-strength metal or metal alloy mesh embodied within the matrix or partially embodied within it at the front face.
In an embodiment of the invention hereinafter to be described the matrix is produced from a matrix material in sheet form having the mesh embodied in it or partially embodied within it at the front face.
In an embodiment of the invention hereinafter to be described the matrix material comprises or includes a synthetic resin. Preferably, the matrix is produced by curing the resin with the mesh embodied in it or partially embodied within it at the front face.
The matrix may be produced from a matrix material which includes one or more reinforcing materials. The reinforcing material may take the form of fibres or discrete particles.
In an embodiment of the invention hereinafter to be described the matrix is of an open-celled structure adapted to receive sound energy. The open-celled structure may be obtained by aggregation of particulate material or by the displacement of material by a dispersion or like technique from a body of material in liquid phase followed by a solidifying step.
Where the structural component is to be used
REFERENCES:
patent: 4055041 (1977-10-01), Adamson et al.
patent: 4122672 (1978-10-01), Lowrie
patent: 5101621 (1992-04-01), Mutch
patent: 5157916 (1992-10-01), Wynosky et al.
Bertsch Richard A.
Kocharov Michael I.
Short Brothers PLC
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