RU2475412C1 - Airliner tight fuselage compartment skin from polymer composite and method of its fabrication - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to aircraft engineering. Proposed skin is composed of laminar skin with gauze of reinforcing ribs. Said gauze comprises helical ribs with lateral surfaces shaped to ordinary right helix with said ribs turned in compartment end area and changing into left helix and vice versa, as well as lengthwise ribs turned in U-like direction at compartment end areas. Said ribs are uniformly distributed over compartment surface and arranged in continuous layers. Said ribs consist of layer of unidirectional fiber strands from composite material bonded together by polymer binder. Outer laminar skin of polymer composite is laid over said gauze of reinforcing ribs.

EFFECT: higher strength in skin end area, reduced weight of joint between skin and mating structures.

11 cl, 17 dwg

Description

FIELD OF THE INVENTION

The invention relates to shell structures and can be used in the manufacture of aircraft products. In particular, the invention relates to the construction of a shell of a compartment of a pressurized fuselage of a main aircraft from a polymer composite material and a method for its manufacture.

State of the art

Known shell structures and methods for their manufacture, which can be used in fairings, bodies and compartments of aerospace products.

An example of such a design is a shell of revolution containing a set of spiral and annular ribs. The ribs are made of unidirectional tape tapes fastened with a polymer binder. Moreover, the annular ribs have cross-sectional profiles in the form of a parallelogram or trapezoid. The cross-sectional area may increase with increasing shell diameter, and the ribs may be provided with inner annular protrusions. The described design allows to reduce the weight of the product while ensuring high strength, reliability and manufacturability. (RF patent 2148496, B32B 3/12, 2000)

The main disadvantages of the known designs is the following:

- insufficient endurance of the structure in the end zone of the shell due to the occurrence of delamination of the material of the ribs and the connection between the ribs and the casing with long cyclic shear loads and longitudinal forces acting on the shell;

- a large mass of the design of the hermetic junction of the shell with the reciprocal structures, due to the need for joining all spiral ribs, longitudinal and additional ribs, as well as sheathing in one cross section of the shell;

- a large difference in the stiffness of the structure in the joint zone of the shell with the reciprocal structures;

- lack of reliability of the design regarding the connection of the annular ribs with the vertices of the zigzag ridges of ridges locally adjacent to the congruent annular ribs.

Disclosure of invention

The objective of the present invention is to eliminate the above disadvantages of known designs.

According to the invention, the shell compartment of the pressurized fuselage of the main aircraft from a polymer composite material is made in the form of a layered casing with a grid of reinforcing ribs, while:

- the grid of reinforcing ribs contains helical ribs with lateral surfaces in the form of surfaces of a straight helical right-hand drive with a turn of these ribs in the area of the end face of the compartment and their transition into screw ribs of the left-hand drive and vice versa, as well as longitudinal ribs with their U-shaped turn in the areas of the ends of the compartment ;

- the ribs are evenly distributed over the surface of the compartment, are formed in layers and are made continuous;

- the ribs consist of layers of unidirectional strands of fibers of the polymer composite material bonded with a polymer binder;

- on the grid of reinforcing ribs formed the outer laminate sheathing of a polymer composite material.

Preferably, the longitudinal ribs in the zones of U-shaped turns are made smoothly decreasing in height from the height of the regular section of the ribs to 1/3 of the height of the regular section with a gradual increase in thickness of the ribs, while the cross-sectional area of the ribs remains constant.

The end zones of the compartment can be equipped with sections made of a polymer composite material and forming a closed ring at each of the ends, while the sections are provided with guide channels for turning longitudinal ribs.

It is advisable that in the places of fastening of the fuselage structural elements between the corresponding ribs were installed connecting fittings.

It is also advisable that between the ribs were installed pre-made from a polymer composite material of the frame of the windows.

Another object of the invention is the shell of the fuselage of the main aircraft, containing stacked compartments, made as described above.

Another object of the invention is a method of manufacturing a shell compartment of a pressurized fuselage of a main aircraft from a polymer composite material made in the form of a layered casing with a grid of reinforcing ribs, in which:

- intersecting ribs of the mesh of reinforcing ribs are made by laying unidirectional strands of fibers impregnated with a polymer binder on a punch in the form of a straight cylinder, the shape of which corresponds to the shape of the compartment being manufactured,

while the ribs on the surface of the punch are formed in the form of helical ribs with lateral surfaces in the form of surfaces of a straight helical right-hand drive with a rotation of these ribs in the region of the end face of the compartment and their transition into helical ribs of the left-hand passage and vice versa, and also in the form of longitudinal ribs with their U- shaped turn in the areas of the ends of the compartment;

moreover, screw and longitudinal ribs are evenly distributed over the surface of the compartment, form them in layers and perform continuous;

- on the obtained ribs form the outer laminate sheathing of a polymer composite material;

- carry out the final thermal polymerization of the shell of the compartment;

- remove the punch from the compartment.

Preferably, before the operation of forming the outer laminate sheathing, liners of a thermally expandable elastic material are installed in the intercostal cells.

Before manufacturing the ribs on the punch in the zones corresponding to the end zones of the compartment, sections made of polymer composite material that form closed rings on the punch can be installed, while guide sections are made on the sections to ensure the longitudinal ribs are turned.

It is advisable to install prefabricated connecting fittings in the places corresponding to the attachment points of the fuselage structure elements in the compartment before making ribs on the punch, while longitudinal grooves are made on the side faces of the fittings.

Also, before manufacturing the ribs on the punch, prefabricated porthole frames from a polymer composite material can be installed.

Brief Description of the Drawings

The invention is illustrated by drawings, in which in a perspective view presents:

figure 1 is a view of the shell compartment of the sealed fuselage;

figure 2 is a view of the helicoid of the right course and the helicoid of the left course;

figure 3 is a view of a continuous rectilinear rib with U-shaped reversals of the direction of the rib;

figure 4 is a view of the lattice structure of the ribs of the shell of the compartment;

figure 5 is a view of the structural elements of the zone near the end of the shell;

figure 6 is a view of the sector section from the axis of the shell;

Fig.7 is a view of the sector section and the zone of the U-shaped reversal of the ribs, from the side of the outer skin;

on Fig - view of the sector section and the guide channel section;

figure 9 is a cross section of a sector section, a cylindrical ring and a longitudinal rib through the zone of a U-shaped turn of the rib;

figure 10 is a view of the lattice structure of the ribs of the shell compartment, porthole frames in the areas of openings for portholes;

figure 11 is a view of the lattice structure of the shell of the compartment in the zones of the openings under the windows, with installed technological elements;

on Fig - view of the lattice structure of the shell of the compartment with a group of connecting fittings;

in Fig.13 is a view of the permanent connection of the lattice structure of the ribs of the shell of the compartment and fitting connecting;

on Fig - view of the position of the longitudinal grooves of the fitting connecting relative to the edges of the shell;

in Fig.15 is a radial section of a fitting fitting;

in Fig.16 is a view of the fitting of the connecting and reciprocal support bracket;

on Fig is a schematic illustration of a method of manufacturing a shell of the fuselage compartment.

The implementation of the invention

The shell of the compartment of the pressurized fuselage of the main aircraft made of polymer composite material (PCM), made in the form of a straight cylinder, contains a grid of reinforcing ribs 1 and covering the ribs of the layered outer skin 2.

A plurality of continuous intersecting ribs forming a mesh shell is made in one piece, in the form of helical and longitudinal ribs 3, 4, from the layers of systems of intersecting helical and longitudinal bundles repeating over the wall thickness of the shell, with unidirectional threads respectively oriented in them, fastened with a polymer binder.

The continuity of each of the screw ribs is ensured by a smooth, in a spatial arc, reversal of the direction forming the lateral surfaces of the ribs in zones 5 near the ends of the cylinder; the right-hand helicoid 6 is changed to the left-hand helicoid 7, and the left-hand helicoid 7 is changed to the right-hand helicoid 6.

Each of the helical ribs contained in the shell forms a continuous (closed) geometric 3D figure.

The continuity of the longitudinal ribs is ensured by a U-shaped turn 8 of the direction of the rectilinear generatrix of the lateral surfaces of the ribs in the areas near the ends of the cylinder, so that, as a result, a continuous geometric 3D figure 4 “closed snake” is formed on the surface of the cylinder forming the surfaces of the longitudinal ribs.

The helical and longitudinal ribs uniformly offset relative to each other on the surface of the cylinder intersect each other, and in all nodes 9 of the spatial mesh lattice no more than two ribs intersect.

The width and height of the ribs, the number and angles of displacement of the ribs, the thickness of the outer skin in various zones of the shell are determined by special calculations for strength and stiffness.

The entire mesh lattice consists of ribs of the same height in any cross section, except for the zones of the U-shaped turn of 8 longitudinal ribs.

In these zones, the longitudinal ribs are made gradually decreasing in height, from a height of 9 regular sections of the ribs to a height of 10, which is about 1/3 of the height of the regular section, with a gradual increase in thickness of the ribs, while the cross-sectional area of the ribs in any section remains constant.

The formation of the longitudinal rib in the zone of the U-shaped turn 8 is performed by layering layers of unidirectional strands of fibers of the polymer composite material, bonded with a polymer binder, in the guide channel 12, designed to form the geometry of the cross section and limit the spread of the longitudinal rib 4. The guide channel 12 is a structural element sector section 13.

Groups of sector sections 13 are reinforcing structural elements in the zones 5 of the shell end and are used as elements of the transverse junction of the fuselage compartments.

A group of sector sections 13 forms in the zone 5 of each of the ends of the shell a composite cylindrical structure fastened from the side opposite to the outer skin 2 with a cylindrical ring 14 made of layered PCM.

The cylindrical ring 14, the group of sector sections 13, and the outer skin 2 thickened in the end zone, together, are the docking elements of the mesh shell of the compartment to make a transverse junction with a similar mesh shell of the adjacent fuselage compartment.

In places where the structural elements of the compartment frame are attached to the PCM shell of the pressurized fuselage compartment, connecting fittings 15 are installed in the mesh shell cells 16.

The structural elements of the compartment frame include the beams of the passenger compartment frame, the reinforcements of the luggage compartment floor frame, the frame beams of the upper interior compartments and luggage racks of the passenger cabin, and reinforcements for installation of aircraft systems and equipment in the compartment.

The connecting fitting 15 is made in the form of a spatial polyhedron. Its largest perimeter is limited by a geometric body consisting of surfaces that form for a group of mutually intersecting and form a typical cell 16 of the mesh shell, between the screw 3 and longitudinal ribs 4.

The thickness of the fitting is limited by the outer skin 2 and the inner forming surface of the mesh shell.

The connecting fitting 15 is made of a structural metal alloy, its surfaces formed by faces along the largest perimeter are profiled along the largest perimeter by groups of longitudinal grooves 17.

The connecting fitting 15, the group of six ribs 3, 4 closest to this fitting and the outer laminate sheath 2 on top of the fitting 15 are an integral power connection. In the contact zone of fitting 15 and ribs 3, 4, strands of unidirectional fibers of a polymer composite material bonded with a polymer binder completely fill the corresponding group of longitudinal grooves 17 of fitting 15 and at the same time supplement the cross-sectional structure of ribs 3, 4 over the profile of grooves 17.

On the side of the inner forming surface of the mesh shell in the fitting 15, a figured recess 18 is made, designed to interface with the mating support bracket 19. The mating support bracket 19, in turn, is connected to one of the structural elements of the fuselage compartment frame.

The portholes 20, which are prefabricated and partially polymerized by partial curing, are made of separate structural elements from a polymer composite material connected by a mixture of a polymer binder and filler from fibers of the chopped composite material, and are installed at a certain step inside the lattice structure of the shell.

The frame of the porthole 20 is limited by the outer skin 2 and the inner forming surface of the mesh shell. The outer side surface of the window frame 20 is made in the form of a smooth surface and is in contact with the side surfaces 22 of the screw ribs 3 of the mesh shell.

The frame of the porthole 20, a group of the closest screw ribs 3 in contact with the frame of the porthole 20 and the outer one, thickened in the area of the opening 23 under the porthole, the laminate casing 2 are an integral connection.

The fuselage shell of the main aircraft contains at least two compartments, each made with the above design features

and joined together by a transverse junction.

Thickened cladding of the mesh shells of the compartments on the inner side of the claddings 2 are joined end-to-end by means of a lining of a three-layer package consisting of arc lining made, in turn, of a hybrid laminated metal-composite material, for example, Ti-Carbon.

A package of arc overlays located in zones 5 near the adjacent ends of the cylinders, thickened laminate sheaths 2 mesh shells, groups of sector sections 13, cylindrical rings 14 are connected from each compartment by a three-row seam of bolt fasteners.

A method of manufacturing a shell of a sealed fuselage compartment consists of the following main steps.

1. The stage of supply of machine equipment for the production of unidirectional prepreg and machine equipment for laying yarn.

2. The stage of development and testing of computer programs for shell manufacturing.

3. The stage of manufacturing assembly tools and fixtures.

4. The stage of manufacturing the PCM elements and metal parts included in the shell assembly.

5. The stage of installation and fixation on the internal equipment of non-removable shell elements.

6. The stage of installation and fixation on snap of removable technological elements.

7. The stage of calculation of the ribs of the retina.

8. The stage of installation and fixation in the cells of the mesh shell of blocks of thermally expandable elastic material.

9. The stage of laying out the layered outer skin.

10. The stage of assembly and fixation of sectional external equipment.

11. The stage of heat treatment and holding snap with the product.

12. The stage of dismantling the external and internal equipment and blocks of elastic material.

13. The recess of the shell compartment, quality control.

The contents of the steps for manufacturing the mesh shell of the compartment:

1. Key machines are purchased and installed, and processes are created that provide the manufacturer with full control over the production lines that create composites and products from them.

The prepreg is obtained by impregnating a strand of fibers with a thermosetting binder with partial curing to the stage of stickiness loss.

2. Create or select from existing software packages for the design of composite products. An on-line control and data acquisition system is being developed, adapted to specific requirements in the process of automatic thread laying.

In the software environment, a program is created with which the AFP machine (Automated Fiber Placement) performs the calculation, and the composite product designer takes a large number of necessary steps to create composite parts and the final integral composite product.

3. Assembly equipment is being manufactured. Type of snap internal sectional metal core, with the possibility of turning the snap around an axis directed along the generatrix of the cylinder.

In the design of the sectional core, a locking element must be present, allowing dismantling through a volume limited to the inner generatrix of the mesh shell.

The core should provide increased stiffness and strength in the radial direction.

Assembly equipment should be installed in the working area of the machine to automatically lay out the prepreg harnesses.

A large-sized thermal chamber is installed near the multi-axis machine for automatic calculation of the prepreg, which encloses the compartment shell in the working volume, together with a set of equipment.

Tooling for the manufacture of components from PCM is made:

- frames of portholes;

- sector sections.

Tooling is made for the manufacture of a set of blocks of thermocompressive elastic tooling.

4. A set of sector sections 13 is made from RMB, a set of frames of portholes 20 is made from RMB. PCM products are polymerized according to the partial curing mode.

A set of connecting fittings 15 is made of a structural metal alloy.

A set of 24 removable technological elements is being manufactured.

Removable technological thrust elements 24 are designed for laying screw ribs 3, in zones 8 of the turns of the directions of the forming ribs, in the end zones 5 of the shell and in the zones of the shell near the openings 23 under the windows.

A set of thermocompression elastic equipment — blocks for filling the cells 16 between the ribs 3, 4 of the mesh shell — is being manufactured.

Blocks are made of thermally expandable material, for example, silicone (silicone) rubber. Due to thermal deformation of the elastomer during heating, the pressure of the final molding of the ribs 3, 4 and the sheathing 2 of the shell is created.

5. On the assembly equipment in the zone 5 of the ends of the shell, two layered rings 14 of PCM are laid out.

6. On the assembly equipment are installed and fixed:

- a set (fixed) of connecting fittings 15;

- a set (fixed) frames of windows 20;

- a set of removable technological thrust elements 24.

On top of the PCM laminated rings 14, sets of sector sections 13 of the PCM are installed and fixed.

7. The simultaneous layer-by-layer laying out of the prepreg from the strands of the prepreg of unidirectional fibers, comprising a grid of screw 3 and longitudinal ribs 4, is performed.

With automatic prepreg laying out:

- filled guide channels 12 sector sections 13;

- filled groups of longitudinal grooves 17 on the connecting fittings;

- window frames 20 are covered by the material of the screw ribs 3;

- technological thrust elements 24 are covered by the material of the screw ribs 3.

When layering the prepreg from strands of unidirectional fibers, normalized tension and local heating in the laying area are performed to adhere to the previously laid material.

In the process of laying out the shell, the assembly tool steadily rotates relative to its longitudinal axis to a position accessible and convenient for operation of the multi-axis robotic head of the machine.

After completion of the calculation of the prepreg, the technological thrust elements 24 are removed from the surface of the assembly tooling.

8. Installation (insertion) is made in all cells 16 between the ribs 3, 4 that make up the lattice structure of the blocks (segments) of thermocompression elastic equipment. The blocks are held in the cells 16 due to the dense normalized clamp silicone rubber to the side surfaces of the ribs 3, 4 cells 16.

9. Layer-by-layer calculation of the layered outer skin 2 of the shell over the ribs 3, 4 and inserted blocks of elastic snap is performed. The thickness of the skin layerwise stepwise increased in the end zones 5 of the shell and around the openings 23 under the windows.

10. On top of the laminated outer skin 2, sections of the outer restrictive metal tooling of the matrix type are installed, with a smooth surface corresponding to the outer surface of the outer skin 2. The sections of the external tooling with fasteners, for example coupling bolts, are combined into a single matrix, characterized by increased stiffness and strength in the radial direction .

11. The kit, consisting of external and internal equipment and a semi-finished mesh shell, is placed inside the thermal chamber.

The operation of thermocompression molding is carried out, combined with the final thermal polymerization of the composite material of the layered casing of 2 ribs 3, 4, sector sections 13, cylindrical rings 14, porthole frames 20.

During heating, the liners increase in volume much more than the volume that limits the intercostal space between the workpiece and rigid rigging, and thereby create the pressure necessary to seal the elements of the mesh shell (up to 30 MPa).

12. Excavation of the snap kit with the fabricated mesh shell of the compartment from the thermal chamber and its installation on the lodgements. Dismantling of sections of external equipment. Excavation of the castle sector of the internal equipment. Sequential dismantling of the remaining sections of the internal equipment, with the removal of parts of the equipment through the end hole of the shell.

Removing from the intercostal space of the shell elements of elastic snap.

13. Quality control of manufacturing the mesh shell of the compartment by non-destructive methods of control of composite material. Weighing and certification of the product.

Claims (11)

1. The shell compartment of the pressurized fuselage of the main aircraft from a polymer composite material, made in the form of a layered casing with a grid of reinforcing ribs, characterized in that
- the grid of reinforcing ribs contains helical ribs with lateral surfaces in the form of surfaces of a straight helical right-hand drive with a turn of these ribs in the area of the end face of the compartment and their transition into screw ribs of the left-hand drive and vice versa, as well as longitudinal ribs with their U-shaped turn in the areas of the ends of the compartment ;
- the ribs are evenly distributed over the surface of the compartment, are formed in layers and are made continuous;
- the ribs consist of layers of unidirectional strands of fibers of the polymer composite material bonded with a polymer binder;
- on the grid of reinforcing ribs formed the outer laminate sheathing of a polymer composite material. 2. The shell compartment of the sealed fuselage according to claim 1, characterized in that the longitudinal ribs in the zones of U-shaped turns are made smoothly decreasing in height from the height of the regular section of the ribs to 1/3 of the height of the regular section with a simultaneous smooth increase in the thickness of the ribs, while the area The cross section of the ribs remains constant. 3. The shell compartment of the pressurized fuselage according to claim 2, characterized in that the end zones of the compartment are equipped with sections made of a polymer composite material and forming a closed ring at each of the ends, while the sections are provided with guide channels for turning longitudinal ribs. 4. The shell compartment of the sealed fuselage according to any one of claims 1 to 3, characterized in that in the places of attachment of the structural elements of the fuselage, connecting fittings are installed between the corresponding ribs. 5. The shell compartment of the pressurized fuselage according to any one of claims 1 to 3, characterized in that between the corresponding ribs installed are made of polymer composite material of the window frame. 6. The shell of the fuselage of the main aircraft, containing docked compartments, made according to any one of claims 1 to 5. 7. A method of manufacturing a shell compartment of a pressurized fuselage of a main aircraft from a polymer composite material made in the form of a layered casing with a grid of reinforcing ribs, in which:
- intersecting ribs of the mesh of reinforcing ribs are made by laying unidirectional strands of fibers impregnated with a polymer binder on a punch in the form of a straight cylinder, the shape of which corresponds to the shape of the compartment being made, while the ribs on the surface of the punch are formed in the form of helical ribs with side surfaces in the form of surfaces of a direct helicoid the right course with the rotation of these ribs in the region of the end face of the compartment and their transition into screw ribs of the left passage and vice versa, as well as in the form of longitudinal ribs with their U-shaped m turn in the areas of the ends of the compartment;
moreover, screw and longitudinal ribs are evenly distributed over the surface of the compartment, form them in layers and perform continuous;
- on the obtained ribs form the outer laminate sheathing of a polymer composite material;
- carry out the final thermal polymerization of the compartment shell;
- remove the punch from the compartment. 8. The method according to claim 7, characterized in that before the operation of forming the outer laminate sheathing, inserts of a thermally expandable elastic material are installed in the intercostal cells. 9. The method according to claim 7, characterized in that before the manufacture of the ribs on the punch in the zones corresponding to the end zones of the compartment, pre-installed sections are made of polymer composite material that form closed rings on the punch, while the sections have guide channels for turning longitudinal ribs. 10. The method according to claim 7, characterized in that before manufacturing the ribs on the punch, pre-made connecting fittings are installed in places corresponding to the attachment points of the fuselage structure elements in the compartment, while longitudinal grooves are made on the side faces of the fittings. 11. The method according to claim 7, characterized in that prior to the manufacture of the ribs on the punch set prefabricated porthole frames of a polymer composite material.

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