MXPA97001206A

MXPA97001206A - Flexible material for use in an inflate structure

Info

Publication number: MXPA97001206A
Application number: MXPA/A/1997/001206A
Authority: MX
Inventors: S Cuccias Robert
Original assignee: Lockheed Corporation
Priority date: 1994-09-30
Filing date: 1997-02-17
Publication date: 1998-02-01

Abstract

The present invention relates to a material suitable for use as the wall of a pressurized container such as the gas bag of a vehicle lighter than air. In detail, the invention includes a first flexible fold (64) having material formed of filaments comprising material formed of filaments, unidirectional at 0 and 90 degrees to each other. A second flexible layer (70 having filament-formed material, unidirectional at 0 and 90 degrees to each other and 45 degrees to the formed filament material of the first fold (64) is included.) The value of the deformation in the failure for the formed material of filaments of the second fold (70) is greater than the material formed of filaments at 0 and 90 degrees of the first layer (64) The first and second fold (64, 70) are joined together by a resin. , an additional film (79) of gas impermeable material and a material resistant to ultraviolet radiation (80) are attached to the first two folds (64, 7).

Description

FLEXIBLE MATERIAL FOR USE IN AN INFLATABLE STRUCTURE BACKGROUND OF THE INVENTION Field of the invention The invention relates to the field of flexible materials, and in particular, to the field of flexible, composite materials. The material has direct application to inflatable structures such as the gas bag for vehicles lighter than air.

Description of the related art In large vehicles, lighter than air, non-rigid, the material used for the airbag must meet a large number of design requirements such as high strength, provide tear resistance, act as a barrier to the gas, not be subject to degradation by the environment, including ultraviolet radiation due to exposure to sunlight. In this way, this material is rolled up REF: 23929 completely being a laminated product of several layers that combines materials with diverse properties. The. Main axial loads in any portion of the wall of the gas bag are 0 degrees to the longitudinal axis of the gas bag and 90 degrees to it (circumferential). In this way, many laminated products include a woven material, formed of filaments, with the material formed of filaments oriented at the 0 and 90 degree angles. Additionally, to support the loads or shear forces, sometimes material formed from filaments with orientations at plus or minus 45 degrees is included to those that support the axial loads. In the initial designs, where the stress levels were low, several layers of cotton woven cloth, impregnated with rubber to provide the gas seal, were often used. Later, artificial fibers such as RAYONMR or DACR0NMR, manufactured by E. I. duPont de Nemours & Company (hereinafter referred to as "DuPont"). The layers of the cotton fabric were at 0 and 90 degrees (axial or resistance bends) for the tensile loads and plus and minus 45 degrees (diagonal bends) for the loads or shear forces. However, this approach, which did not always result in an optimal resistance design for the strength required to withstand the shear stress, was typically much smaller than the capacity of the diagonal bends. Using the same material for both axial stress loads as well as diagonal loads (shear) often resulted in a weight disadvantage. Some modern designs use a woven polyester fiber such as DACR0NMR for the material that supports the axial load at 0 and 90 degrees. Also, a film of material that is impervious to helium such as a polyester terephthalate that serves as the gas barrier also bears some of the load or shear stress. A typical polyester terephthalate is sold by DuPont under the trade name MYLARMR. The woven polyester fiber such as DACRONMR has a very large deformation at the failure value, approximately 20 percent. However, in non-rigid, large aircraft, the resistance requirements have dictated the use of materials of a very high strength such as a thermotropic polyester-polyarylate fiber (spunbond), glass, liquid, for example VECTRANMR manufactured by Hoechat Celanese, Germany to withstand axial loads. Another high strength material is a lyotropic aromatic polyaramide fiber (spun by solvent), such as KEVLARMR, which is manufactured by DuPont. However, both VECTRANMR and KEVLARMR have a very small value of deformation at the fault value, in the order of 4 percent. If the diagonal layers were made of the same material, the biaxial load on the fibers at 0 and 90 degrees will transfer significant load to the diagonal layers at 45 degrees. The requirement of these layers to work as hard as the bends at 0 and 90 °, introduces the potential failure mode, or a weakening of the system. Actually, having a diagonal layer with superior elongation than grades 0 and 90 (resistance fibers) avoids premature failure in the diagonal fold to the final load in the resistance fibers. Some of the prior art teaches, far from the use of this concept, for example, German Patent No. DE 3702936"Fiber Composite Material With high Tensile And High Modulus Fiber In different Orientations" by S. Roth et al. Roth et al. Teach the use of fibers with high strength and elongation at 0 and 90 degrees in conjunction with fibers at 45 degrees that have a high elastic modulus for use in composite, rigid structures. In this way, the value of the deformation in the failure of the fibers at plus or minus 45 degrees is less than the fibers at 0 and 90. In US Pat. No. 4,770,918"Diagram For Producing Sound" by A. Hayashi, describes a flexible diaphragm for producing sound, having at least one layer of a first fabric fabric having little elongation and at least two layers of a second fabric fabric having a high elongation. The first and second genera are placed in such a way that the warp of them intersects each other at between 10 and 80 degrees, so that a lengthening of the diaphragm in the direction of the warps of the first genus is generally equal to elongation of the diaphragm in a direction inclined at an angle of 45 degrees with respect to the direction of the warps of the first genre. This allows for easy adjustment of the diaphragm. This invention, of course, will produce an inefficient pressurized structure. Other patents of general interest, in which materials of different properties are combined, in a flexible, individual structure are US Pat. Nos. 5,189,280"Three Dimensional Fiber Structures Having Improved Penetration Resistance" by GA Harpell, et al., 4,871,598"Container With Flexible Walls "by E. Potente, et al. And 5,215,795" Shoc -Absorbing Air Bag "by M. Matsumoto, et al. In this way, it is the main object of the invention to provide a laminated product, suitable for the wall of pressurized, flexible containers. It is another main object of the invention to provide a laminated material, suitable for the wall of containers, pressurized, flexible, wherein the folds supporting the loads or shear forces, diagonal have a deformation greater than the value of failure that the folds that support the Tension loads, axial. It is still a further object of the invention to provide a laminated material, suitable for pressurized containers of flexible wall, which is not degraded by ultraviolet radiation. It is still a further object of the invention to provide a laminated material, suitable for the wall of pressurized, flexible containers which are suitable for containing helium gas.

It is another object of the invention to provide a laminated material, suitable for the wall of pressurized, flexible containers that can be easily sealed together.

BRIEF DESCRIPTION OF THE INVENTION The invention is a material, suitable for use as the wall of a pressurized container such as the gas bag of a vehicle lighter than air. In detail, the invention includes a first flexible layer comprising material formed from filaments, unidirectional at 0 and 90 degrees to each other. The filament formed material of the first layer can be unidirectional folds separated at 0 and 90 degrees or woven fabric. A second flexible layer having material formed of filaments is included, unidirectional at 0 and 90 degrees to each other and at 45 degrees to the material formed of filaments of the first layer. The material formed of filaments of the second layer may also consist of unidirectional folds, separated at 0 and 90 degrees or woven fabric. In addition, the material formed of filaments in both layers may be in the form of individual threads or strands. Also, either or both layers can be divided into a number of thinner layers and mixed together in any way. Critical for the invention is that the value of deformation in the failure for the material formed of filaments of the second layer must be greater than the material formed of filaments at 0 and 90 degrees of the first layer. The first and second layers are joined together by a resin. The first and second bends can also be knitted or sewn together with or without the resin to add additional strength. Preferably, an additional film of a gas-impermeable material and a material resistant to ultraviolet radiation are attached to the first two layers. The new aspects that are believed to be characteristic of the invention, both in terms of their organization and method of operation, together with the objects and additional advantages thereof, will be better understood from the following description in conjunction with the accompanying drawings. , in which the currently preferred embodiments of the invention are illustrated by way of example. However, it will be expressly understood, that the drawings are for the purposes of illustration and description only and are not proposed as a definition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a vehicle lighter than air.

Figure 2 is a perspective view of a portion of the wall of the gas bag made of the flexible fabric laminate product illustrating the major axis of alignment of the filament formed material.

Figure 3 is a perspective, partial view of a portion of the laminated product of fabric, wherein the first and second layers are woven materials.

Figure 4 is a side, partial view of a second embodiment of the laminated product of fabric, wherein the material formed of filaments that integrates both the first and the second layer are unidirectional folds that are sewn together.

Figure 5 is a view of a third embodiment of the laminated product of fabric, perpendicular to it, wherein the material formed of filaments that integrates both the first layer and the second layer are unidirectional folds that are woven together. *, ' Figure 6 is a side view of the third embodiment of the laminated product of gender illustrated in Figure 5.

Figure 7 is a diagram that delineates the resistance of the fiber to 0 and 90 degrees as a function of the ratio of the deformation ratio in fiber failure from 0 to 90 degrees to the fiber at plus or minus 45 degrees.

DESCRIPTION OF THE PREFERRED MODE 20 Illustrated in Figure 1 is a perspective view of a vehicle lighter than air, generally designated by the number 10. The vehicle 10 includes a gas bag 12 having a shaft longitudinal 13A, a lateral axis 13B and an axis r vertical 13C. A nacelle 14 is suspended from the gas bag and incorporated into a plurality of propulsion systems 16 mounted thereon. As the vehicle size increases, large levels of effort are introduced into the gas bag 12. Additionally, gas bag 12 must be: impermeable to helium gas; not be affected by the environment (including ultraviolet radiation); able to be stitched and be tolerant or damage. The satisfaction of all these requirements requires a flexible, multilayer, laminated fabric made of different materials that have specific mechanical properties. In Figure 2, a portion of the flexible wall 20 having an inner surface 22 and an outer surface 24 is illustrated and is composed of multiple layers of material formed by filaments in a manner discussed below. The axial loads, main 0 are introduced along the axis to 0 degrees, aligned with the longitudinal axis 13A and indicated by the number 26, and 90 degrees to them indicated by the number 28. In this way, the material formed of filaments that supports the main load 5 is aligned with these axes. The loads or shear stresses are supported by the material formed of filaments aligned with the directions at plus and minus 45 degrees indicated by the numbers 30 and 32. The angle of 45 degrees can be adjusted based on the requirements in detail of the specific application . With reference to Figure 3, the flexible wall 20 is made of (starting from the inner surface 22) a first resin layer 40 which is joined to a first layer 42 of woven yarn with individual strands at 0 and 90 degrees. The resin layer 40 and the subsequent layers of resin are preferably a polyurethane. The first layer 42 is made of a high strength yarn such as polyester polyacrylate (VECTRAN ™), thermotropic (melt-spun), glass, liquid fiber. A lyotropic aromatic polyaramide (KEVLARMR) fiber (solvent spun) is also suitable. A second resin layer 44 separates the first layer 42 from a second layer 46 of filament-formed material, woven with individual strands at about 45 degrees. A third layer of resin separates the second layer 46 from a film of material that is substantially impermeable to helium gas such as polyester terephthalate (MYLARMR). Finally, a fourth layer of resin is used to bond an outer layer of a material that is resistant to ultraviolet radiation degradation and also provides protection from wind erosion and the like. This material is a polyvinyl fluoride fiber, which is sold under the trade name TEDLARMR by DuPont. As illustrated in Figure 3, the material is illustrated in its "bonded form". An alternative to MYLARMR or TEDLARMR is to increase the resin content of the laminated product to impregnate the fibers creating a gas impermeable layer. The critical factor in the selection of the materials for the wall 20 of the gas bag, besides being chemically compatible, is that the deformation (inch per inch) in the failure of the second layer of the material formed of filaments is greater than the deformation in the fault for the first layer. This will ensure that the deformations introduced by axial loads at 0 and 90 degrees in layer 42 do not create faults when transferred up to layer 46. Furthermore, it is highly desirable to have a material of high deformation ratio for second layer 46 since reduces the possibility of local stress concentrations.

In Figure 4, a second embodiment of the subject material is illustrated and indicated in general by the number 60. Starting from the bottom up, the material comprises a first layer of resin 61; a first layer 62 having a fold 64 of material formed from filaments, unidireccinal at 0 degrees and a fold at 66 to 90 degrees; a second layer 70 having a fold 72 of material formed of filaments, unidireccinal to plus 45 degrees and a second bend 74 to minus 45 degrees. The four folds 62, 64, 72 and 74 are sewn together, with the stitches indicated by number 78. A barrier layer is attached to the helium gas of the material such as layer 79 of MYLARMR on the resin layer 76 and is it binds by means of a resin layer 82 a final layer 80 of ultraviolet ray resistant material such as TEDLARMR. As in the first embodiment illustrated in Figure 3, when the individual layers are joined together, the first and second layers, 62 and 70, respectively, become encapsulated in a flexible resin matrix. It should be noted that the first and second woven layers of the material 42 and 46, illustrated respectively in Figure 3 can also be sewn together.

In Figures 5 and 6, a third embodiment is illustrated, generally indicated by the number 90, wherein the first and second layers 62 and 70 shown in Figure 4 are woven together as indicated by number 92. The rest of the material 90 will be similar to Figure 4. Again, it should be noted that the first and second woven layers of material 42 and 46, respectively, illustrated in Figure 3, can also be woven together to improve strength. As mentioned previously, it is critical for the invention that the value of deformation in the failure for the material formed of filaments in the second layer to more than minus 45, must be greater than the material formed of filaments at 0 and 90 degrees for the first layer. Figure 7 shows the importance of this feature. The strength of the material under uniaxial and diaxial loading conditions is shown by a series of different deformation values for the biaxial material. The deformation of the biaxial material to the fault is divided by the deformation of the material at 0 and 90 degrees to the fault to produce a deformation relation. If the ratio is less than one, the diagonal layer at plus or minus 45 degrees will fail first, a ratio greater than one means that the layer at 0 and 90 degrees will fail first. The severe penalty for low relationships is obvious. While the invention has been described with reference to a particular embodiment, it should be understood that the embodiments are specifically illustrative, since there are numerous variations and modifications that can be made by those skilled in the art. In this way, the invention is to be constructed as limited only by the spirit and scope of the appended claims.

INDUSTRIAL APPLICABILITY The invention has applicability to the composite products industry and also to the aircraft industry.

It is noted that in relation to this date, the best method known by the applicant to carry out the present invention, is the conventional one for the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property:

Claims

1. A material for a pressurized container, characterized in that it comprises: at least a first flexible layer comprising material formed of filaments, unidirectional at 0 and 90 degrees to each other; at least a second layer comprising material formed of filaments, unidirectional at 0 and 90 degrees to each other and at 45 degrees to and having a value of deformation in the fault greater than, the material formed of filaments at 0 and 90 degrees of at least one first layer; and at least one first and second layer joined together.

2. The material according to claim 1, characterized in that at least one first and one second layer are joined together. 3. The material according to claim 2, characterized in that at least one first and one second layer are joined together by joining. 4. The material according to claim 2, characterized in that the material formed of filaments at 0 and 90 degrees of the at least one first layer are woven together. 5. The material according to claim 4, characterized in that the material formed of filaments at 0 and 90 degrees of at least one second layer are woven together. 6. The material according to claim 5, characterized in that the filament-formed, unidirectional material of at least one first and second layers are in the form of yarns. 7. The material according to claim 1, characterized in that at least one first layer is selected from the group consisting of thermotropic polyester poly (spunbond), crystalline, liquid and lyotropic aromatic polyaramide fibers (spinning by solvent). 8. The material according to claim 4, characterized in that the filament formed material of the second layer is a polyester fiber. 9. The material according to claim 1, or 2, or 3, or 4, or 5, or 6, or 7, or 8, characterized in that at least a first and a second layer are woven together. 10. The material according to claim 1, 6 2, or 3, or 4, or 5, 6 6, or 7 or 8, characterized in that at least a first and a second layer are sewn together. 11. The material according to claim 1, or 2, or 3, or 4, or 5, or 6, or 7 or 8, characterized in that it further comprises a gas-impermeable, flexible sheet of material attached to at least one first and a second layer. 12. The material according to claim 11, characterized in that the gas impermeable sheet is a polyester terephthalate. 13. The material according to claim 10, characterized in that it also comprises a sheet of a sheet protecting the ultraviolet radiation of material joined at least a first and a second layer. 14. The material according to claim 13, characterized in that the sheet of ultraviolet radiation protection material is polyvinyl fluoride. 15. A material for a pressurized container, characterized in that it comprises: a first flexible fabric comprising yarns of material formed of filaments, woven together in a 90 degree design; a second flexible fabric comprising yarns of material formed from filaments at plus and minus 45 degrees and having a value of deformation at the fault greater than the material formed from filaments at 0 and 90 degrees of the first fabric; and the first and second fabrics joined together by a resin matrix. 16. The material according to claim 15, characterized in that a film of gas impermeable material on the opposite side of the first flexible fabric. 17. The material according to claim 16, characterized in that a fourth fabric of a material resistant to ultraviolet radiation is bonded onto the film. 18. The material according to claim 15, or 16, or 17, characterized in that the first and the second fabric are woven together. 19. The material according to claim 15, or 16, or 17, characterized in that the first and the second fabric are sewn together. CLAIMS AMENDED [Received by the International Bureau on August 7, 1995 (07.08.1995); original claims 1, 3, 4, 7, 9-13, 15 and 16 amended; original claim 2 canceled; remaining claims without change (2 pages)] 1. A material for a wall of a pressurized container, characterized in that it comprises: at least a first flexible layer comprising material formed of filaments, "unidirectional at 0 and 90 degrees to each other, at least a second layer comprising material formed of filaments, unidirectional at 0 and 90 degrees to each other and at 45 degrees A and having a value of deformation in the fault greater than, the material formed of filaments at 0 and 90 degrees of at least one first layer, and at least one first and second layer joined together jointly.

3. The material according to claim 1, characterized in that at least one first and one second layer are joined together by joining.

4. The material according to claim 1, characterized in that the material formed of filaments at 0 and 90 degrees of the at least one first layer are woven together.

5. The material according to claim 4, characterized in that the material formed of filaments at 0 and 90 degrees of at least one second layer are woven together.

6. The material according to claim 5, characterized in that the unidirectional filament-formed material of at least one first and second layers is in the form of yarns.

7. The material according to claim 6, characterized in that at least one first layer is selected from the group consisting of thermotropic polyester poly (spunbond), crystalline, liquid polyester fibers and lyotropic aromatic polyaramide (solvent spun).

8. The material according to claim 4, characterized in that the filament formed material of the second layer is a polyester fiber.

9. The material according to claim 1, or 3, or 4, or 5, or 6, or 7, or 8, characterized in that at least one first and second layers are woven together.

10. The material according to claim 1, or 3, or 4, or 5, or 6, or 7 or 8, characterized in that at least a first and a second layer are sewn together.

11. The material according to claim 1, or 3, or 4, or 5, or 6, or 7 or 8, characterized in that it also comprises a sheet impermeable to gas, flexible material attached to at least a first and a second layer .

12. The material according to claim 11, characterized in that the gas impermeable sheet is a polyester terephthalate.

13. The material according to claim 10, characterized in that it also comprises a sheet of ultraviolet radiation protection material attached to at least a first and a second layer.

14. The material according to claim 13, characterized in that the sheet of ultraviolet radiation protection material is polyvinyl fluoride.

15. A material for a wall of a pressurized container, characterized in that it comprises: a first flexible fabric comprising yarns of material formed of filaments, woven together in a 90 degree design; a second flexible fabric comprising yarns of material formed from filaments at plus and minus 45 degrees and having a value of deformation at the fault greater than the material formed from filaments at 0 and 90 degrees of the first fabric; and the first and second fabrics joined together by a resin matrix.

16. The material according to claim 15, characterized in that a film of gas impermeable material is attached on the opposite side of the first flexible fabric to which the second flexible fabric is attached.