Structure for containing substances and method of integrating a tank skirt and a tank

Abstract

Disclosed herein is a structure for containing a substance and a method of integrating a tank skirt and a tank. The structure includes a tank having an outer cylindrical surface and a domed end. The structure also includes a tank skirt positioned circumferentially around the tank. The wall of the tank and the wall of the tank skirt form two sides of a y-shaped connection between the tank and the tank skirt. The y-shaped connection includes a wedge-shaped structure located between the tank and the tank skirt. In addition, the thickness of at least one of the tank wall or the tank skirt wall forming the y-shaped connection gradually decreases, so that the gradually decreasing thickness of at least one of the tank wall or the tank skirt wall has a greater thickness at the y-shaped connection than away from the y-shaped connection.

Description

Technical Field

[0001] The present disclosure relates generally to pressurized vessels and, more particularly, to the design and method of manufacturing a structural joint for two load-bearing walls of a pressurized vessel. Background Art

[0002] Potentially structurally harmful stress rises typically occur at structural joints between a pressurized wall of a pressure vessel and another load-bearing wall of the pressure vessel. Existing solutions for reducing stress rises at such structural joints are primarily applicable to metal pressure vessels. Solutions that help reduce stress rises in metal pressure vessels are typically ineffective at reducing stress rises in pressure vessels made of composite structures. Furthermore, solutions intended to reduce stress rises in composite pressure vessels require expensive specialized materials. As a result, it is difficult to reduce stress rises at wall joints of pressurized vessels made of composite materials in an effective, simple, and cost-effective manner. Summary of the invention

[0003] The subject matter of the present application has been developed in response to the current state of the art, and in particular in response to problems and needs associated with stress risers (stress singularities) that occur at a structural joint of a pressurized wall of a pressure vessel with another load-bearing wall when the pressure vessel wall is split into two branches, wherein one branch is used for a pressure-retaining dome and the second branch can interface with another structure. In general, the subject matter of the present application has been developed to provide a design and manufacturing method for such a structural joint of two load-bearing walls that overcomes at least some of the above-mentioned disadvantages of the prior art.

[0004] Disclosed herein is a structure comprising a tank having an outer cylindrical surface and a domed end. The structure also includes a tank skirt disposed circumferentially around the tank. The wall of the tank and the wall of the tank skirt form two sides of a y-shaped connection between the tank and the tank skirt. The y-shaped connection includes a wedge-shaped structure located between the tank and the tank skirt. In addition, the thickness of at least one of the tank wall or the tank skirt wall forming the y-shaped connection gradually decreases, so that the gradually decreasing thickness of at least one of the tank wall or the tank skirt wall has a greater thickness at the y-shaped connection than away from the y-shaped connection. The aforementioned subject matter of this paragraph characterizes Example 1 of the present disclosure.

[0005] The thickness of the tank wall forming the y-shaped connection gradually decreases. The foregoing subject matter of this paragraph characterizes Example 2 of the present disclosure, wherein Example 2 also includes subject matter according to Example 1 above.

[0006] The thickness of the wall of the tank forming the y-connection is greater along the length of the y-connection and the length extending beyond each side of the y-connection than away from the y-connection. The foregoing subject matter of this paragraph characterizes Example 3 of the present disclosure, wherein Example 3 also includes subject matter according to Example 2 above.

[0007] The tank includes a stack of plies. The ply drop rate of the stack of plies along the y-shaped connection is not less than 30: 1. The foregoing subject matter of this paragraph characterizes Example 4 of the present disclosure, wherein Example 4 also includes subject matter according to Example 3 above.

[0008] The thickness of the tank skirt wall forming the y-shaped connection gradually decreases. The foregoing subject matter of this paragraph characterizes Example 5 of the present disclosure, wherein Example 5 also includes subject matter according to any one of Examples 1-4 above.

[0009] The thickness of the wall of the tank skirt forming the y-connection is greater along the length of the y-connection and the length extending beyond each side of the y-connection than away from the y-connection. The aforementioned subject matter of this paragraph characterizes Example 6 of the present disclosure, wherein Example 6 also includes the subject matter according to Example 5 above.

[0010] The stiffness of the tank wall and the stiffness of the wedge-shaped structure are substantially the same.The foregoing subject matter of this paragraph characterizes Example 7 of the present disclosure, wherein Example 7 also includes subject matter according to any one of Examples 1-6 above.

[0011] The thickness of the tank wall forming the y-shaped connection gradually decreases. The thickness of the tank skirt wall forming the y-shaped connection gradually decreases. The aforementioned subject matter of this paragraph characterizes Example 8 of the present disclosure, wherein Example 8 also includes subject matter according to any one of the above Examples 1-7.

[0012] The tank and the wedge-shaped structure are made of different forms of materials from the same family of composite materials. The tank includes a belt, and the wedge-shaped structure includes a fabric. The foregoing subject matter of this paragraph characterizes Example 9 of the present disclosure, wherein Example 9 also includes subject matter according to any of Examples 1-8 above.

[0013] The stack of wedge-shaped structures is configured such that a first fabric ply of the wedge-shaped structures is oriented in a different direction than a second fabric ply adjacent to the first fabric ply.The foregoing subject matter of this paragraph characterizes Example 10 of the present disclosure, wherein Example 10 also includes subject matter according to any of Examples 1-9 above.

[0014] The fabric ply closest to the tank is oriented at forty-five degrees relative to the axial direction of the tank.The foregoing subject matter of this paragraph characterizes Example 11 of the present disclosure, wherein Example 11 also includes subject matter according to any of Examples 1-10 above.

[0015] The tank is a pressurized container.The foregoing subject matter of this paragraph characterizes Example 12 of the present disclosure, wherein Example 12 also includes subject matter according to any of Examples 1-11 above.

[0016] The tank is a composite cryogenic fuel tank.The foregoing subject matter of this paragraph characterizes Example 13 of the present disclosure, wherein Example 13 also includes subject matter according to any one of Examples 1-12 above.

[0017] The structure forms part of a spacecraft.The foregoing subject matter of this paragraph characterizes Example 14 of the present disclosure, wherein Example 14 also includes subject matter according to any of Examples 1-13 above.

[0018] The present invention also discloses a structure within a spacecraft. The structure includes a pressurized tank, which includes an outer cylindrical surface and a dome end. The structure also includes a tank skirt placed circumferentially around the pressurized tank. The wall of the pressurized tank and the wall of the tank skirt form two sides of a y-shaped connection between the pressurized tank and the tank skirt. The y-shaped connection includes a wedge-shaped structure located between the pressurized tank and the tank skirt. The thickness of the wall of the pressurized tank forming the y-shaped connection gradually decreases, so that the wall thickness of the pressurized tank at the y-shaped connection is greater than the thickness away from the y-shaped connection. The wedge-shaped structure includes a stack of multiple fabric plies. The stack of multiple fabric plies of the wedge-shaped structure includes a first fabric ply and a second fabric ply, and the orientation of the second fabric ply is different from the direction of the first fabric ply. The aforementioned subject matter of this paragraph characterizes Example 15 of the present disclosure.

[0019] The first fabric ply is closer to the pressurized tank than the second fabric ply. The first fabric ply is oriented at forty-five degrees relative to the axial direction of the tank. The foregoing subject matter of this paragraph characterizes Example 16 of the present disclosure, wherein Example 16 also includes subject matter according to Example 15 above.

[0020] Also disclosed herein is a method comprising laying a wedge-shaped structure at a conical thickness portion of a domed end of a tank after the tank has been cured. The method also comprises curing the wedge-shaped structure after it is laid at the domed end of the tank. The method also comprises, after curing the wedge-shaped structure, laying a tank skirt around the wedge-shaped structure and the tank so that the wall of the tank and the wall of the tank skirt form two sides of a y-shaped connection between the tank and the tank skirt, with the wedge-shaped structure located on both sides. The foregoing subject matter of this paragraph characterizes Example 17 of the present disclosure.

[0021] The step of laying the wedge-shaped structure includes orienting a first fabric ply of the wedge-shaped structure in a different direction than a second fabric ply adjacent to the first fabric ply.The foregoing subject matter of this paragraph characterizes Example 18 of the present disclosure, wherein Example 18 also includes subject matter according to Example 17 above.

[0022] The fabric ply of the wedge structure closest to the tank is oriented at forty-five degrees relative to the axial direction of the tank.The foregoing subject matter of this paragraph characterizes Example 19 of the present disclosure, wherein Example 19 also includes subject matter according to any of Examples 17 or 18 above.

[0023] Laying the tank skirt around the wedge structure and the tank also includes gradually reducing the thickness of the tank skirt so that the thickness of the tank skirt is greater at the y-connection than away from the y-connection. The foregoing subject matter of this paragraph characterizes Example 20 of the present disclosure, wherein Example 20 also includes subject matter according to any one of the above Examples 17-19.

[0024] The described features, structures, advantages and / or characteristics of the subject matter of the present disclosure can be combined in any suitable manner in one or more examples and / or embodiments. In the following description, many specific details are provided to give a thorough understanding of the examples of the subject matter of the present disclosure. Those skilled in the relevant art will recognize that the subject matter of the present disclosure can be implemented in the absence of one or more of the specific features, details, parts, materials and / or methods of a particular example or embodiment. In other examples, additional features and advantages that are not present in all examples or embodiments may be recognized in certain examples and / or embodiments. In addition, in some cases, well-known structures, materials or operations are not shown or described in detail to avoid blurring the various aspects of the subject matter of the present disclosure. According to the following description and the attached technical solutions, the features and advantages of the subject matter of the present disclosure will become more completely apparent, or can be known by the practice of the subject matter described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order that the advantages of the subject matter may be more readily understood, a more particular description of the subject matter briefly described above will be provided by reference to specific examples shown in the accompanying drawings. Understanding that these drawings depict only typical examples of the subject matter and are therefore not to be considered limiting of its scope, the subject matter will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0026] Figure 1 is a cross-sectional view of a Y-shaped connection between a tank and a tank skirt according to one or more examples of the present disclosure;

[0027] Figure 2 is an internal side view of a launch vehicle according to one or more examples of the present disclosure, showing the location of the y-shaped connection of the pressurized vessel;

[0028] Figure 3 is a perspective view of the interior of a launch vehicle according to one or more examples of the present disclosure, showing the location of the y-shaped connection of the pressurized vessel;

[0029] Figure 4 is a cross-sectional view of a Y-shaped connection between a tank and a tank skirt according to one or more examples of the present disclosure;

[0030] Figure 5 is a perspective view of a pressurized tank according to one or more examples of the present disclosure;

[0031] Figure 6 is a close-up perspective view of a pressurized tank according to one or more examples of the present disclosure;

[0032] Figure 7 is a close-up perspective view of a pressurized tank according to one or more examples of the present disclosure;

[0033] Figure 8 is a close-up perspective view of a pressurized tank according to one or more examples of the present disclosure;

[0034] Fig. 9 is a close-up perspective view of a pressurized tank and a tank skirt according to one or more examples of the present disclosure;

[0035] Fig.10 is a perspective view of a pressurized tank and a tank skirt according to one or more examples of the present disclosure;

[0036] Fig.11 is a cross-sectional side view of a wedge-shaped structure according to one or more examples of the present disclosure; and

[0037] Fig.12 A schematic flowchart of a method according to one or more examples of the present disclosure. DETAILED DESCRIPTION

[0038] Throughout the specification, reference to "one example," "example," or similar language means that a particular feature, structure, or characteristic described in conjunction with the example is included in at least one example of the present disclosure. Throughout the specification, the appearance of the phrases "in one example," "in an example," and similar language may, but need not, all refer to the same example. Similarly, use of the term "embodiment" means an embodiment having a particular feature, structure, or characteristic described in conjunction with one or more examples of the present disclosure, however, an embodiment may be associated with one or more examples if no explicit association is indicated.

[0039] refer to Figure 1 , which shows an example of a conventional y-connection 12 between a tank 14 and a tank skirt 16. The conventional y-connection 12 includes a softening strip 18 between the tank 14 and the tank skirt 16. In many cases, the relative stiffness of the softening strip 18 is much lower than the stiffness of the tank 14 or the tank skirt 106. As described in more detail below, the y-connection 12 will include stress concentrations. Stress concentrations or stress risers are easily formed at the first location 19 and the second location 17.

[0040] The relative forces exerted on the pressurized wall of the tank 14 and the other load-bearing wall of the tank skirt 16 produce structurally detrimental stresses (or stress singularities, stress concentrations, or stress risers) at the first location 19 and the second location 17. Some existing solutions to compensate for stress concentrations in metal structures include welded or bolted connections. Such solutions are not effective for composite structures. In addition, bolted or welded connections are susceptible to leakage, which can create a hazardous situation if the tank 14 is pressurized and filled with highly flammable materials, which is often the case.

[0041] like Figure 1As shown, one existing solution for reducing stress concentrations in composite structures uses special materials in the form of softening strips 18. In such solutions, the material (usually certain composite preforms at low temperatures, or rubber in other temperature ranges) is designed and manufactured to be much softer than the stiffness of the adjacent walls of the tank 14 and the tank skirt 16. The purpose is to gradually reduce the stress at the stress concentration of the joint. Such materials are expensive and difficult to develop and manufacture for low temperature applications. Moreover, rubber-like materials are not suitable for low temperature applications, or may be too soft in other temperature ranges. In addition, the use of softening strips 18 often requires excessive trial and error because the stiffness (especially at low temperatures) cannot always be accurately predicted.

[0042] Compared to conventional techniques, the examples described herein allow for a more robust and cost-effective design to reduce stress concentrations in the joint between a wall of a pressure vessel and an adjacent load-bearing wall (which may be pressurized or unpressurized). More specifically, the examples described herein include a third abutment member at the joint between the load-bearing walls and / or gradually adjusting the thickness and stackup of one or both of the load-bearing walls.

[0043] refer to Figure 2 and Figure 3 , which shows two examples of spacecraft 101 including various locations of a y-connection 102. In these examples, the y-connection 102 is a joint between a dome tank and a tank skirt. The tank skirt forms a structural component of the spacecraft 101, such as an outer sidewall. The extreme conditions (including cryogenic conditions) that the spacecraft 101 may be subjected to require appropriate load sharing between the walls on each side of the y-connection 102.

[0044] Reference now Figure 4 , according to some examples of the present disclosure, shows a cross-sectional view of a structure 100 including a y-shaped connection 102 between a tank 120 and a tank skirt 110. In some examples, the tank 120 is a tank having an outer cylindrical surface 122 and one or two domed ends 124 (e.g., see Figure 5 ) container. Figure 2 and Figure 3 As shown, the length of the tank 120 can vary, as shown by the varying sizes of the tank 120 and the corresponding tank skirt 110. In some examples, the tank 120 includes two rounded ends 124 and will form an annular or continuous y-shaped connection 102 with one or more tank skirts 110.

[0045] As already described herein, in some examples, tank 120 forms part of a spacecraft or launch vehicle and is subjected to cryogenic or other extreme space or launch conditions. In some examples, tank 120 is made of a composite material, as used herein, including a fiber-reinforced polymer material. Tank 120 may be a pressurized tank and may be referred to as a pressurized vessel or pressure vessel. In some examples, tank 120 contains combustible materials, such as liquid oxygen, liquid hydrogen, liquid methane or other fuels under pressure.

[0046] The structure 100 includes a tank skirt 110 coupled to a tank 120. The tank skirt 110 includes an inner cylindrical surface 112 coupled to an outer cylindrical surface 122 of the tank 120. In some examples, the tank skirt 110 is made of a composite material, which may be the same or different than the composite material of the tank 120. The tank skirt 110 forms a structural portion of a portion of an aircraft, a spacecraft, or a rocket or launch vehicle (see generally Figure 2 and Figure 3 ). The tank skirt 110 is bonded to or otherwise integrated with (eg, co-formed with) the tank 120 .

[0047] As the tank 120 transitions from the outer cylindrical surface 122 to the domed end 124, the tank 120 and the tank skirt 110 form a y-type connection 102, wherein the walls of the tank 120 diverge from the walls of the tank skirt 110. Thus, the walls of the tank 120 and the walls of the tank skirt 110 form two opposing sides of the y-type connection 102. The y-type connection 122 extends continuously around the circumference of the tank 120, and is generally considered to define a space having a substantially triangular cross-sectional shape along a plane parallel to the central axis of the tank 120 between the tank 120 and the tank skirt 110. Stress concentrations at and near the y-type connection 102 should be considered to ensure that the tank 120 and the tank skirt 110 are structurally sound. The examples of the present disclosure address such stress concentrations without excessive cost and weight, and enable the design and manufacture of composite y-type connections without the need for experimental verification of structural properties.

[0048] like Figure 4As shown, according to one example, stress concentration is resolved by a wedge-shaped structure 140 located between the tank 120 and the tank skirt 110. The wedge-shaped structure 140 extends annularly or continuously around the circumference of the tank 120 within the space defined by the y-shaped connecting portion 102. In some examples, the wedge-shaped structure 140 is made of a composite material. In some examples, the wedge-shaped structure 140 is made of the same material or the same composite material series as the tank 120. However, in some embodiments, although the material is the same, it can have a different form compared to the form of the tank 120. For example, the tank 120 can be made of a belt, and the wedge-shaped structure can be made of a fabric with the same composition (matrix and fiber). The composite "series" have the same basic composition, fibers and matrix, but can be formed into different forms (belts, fabrics and other subtle changes, such as the width of a slit belt may be only 1 / 8 inch, while the width of a wide belt may be 2 / 8 inch), which allows different manufacturing processes (hand-laid, automatic belt placement, fiber placement, etc.). Each compound in the series is made of the same or similar ingredients and in forms that are compatible with each other so that they can be used together, for example, you can put layers of cloth and layers of tape on a laminate.

[0049] In some examples, the wedge-shaped structure 140 is larger than the softening strip 18 (such as Figure 1 The size of the wedge-shaped structure can be only about one fifth of the size of the softening strip.

[0050] In some examples, the stiffness of the walls of the tank 120 and / or the tank skirt 110 and the wedge-shaped structure 140 is substantially the same. As used herein, in the context of stiffness, substantially identical devices fall into the same range or the same order of magnitude. For example, the stiffness of the tank wall may be 5 msi (1 million pounds per square inch) in the axial direction and 10 msi in the hoop direction; while the stiffness of the wedge-shaped structure 140 may be 7 msi in both directions. Typically, in some examples, the stiffness of the tank 120 and the wedge-shaped structure 140 is between 5 msi and 10 msi. In another specific example, the stiffness of the tank 120 in the axial direction is 6.6 msi, in the hoop direction is 8.18 msi, and the stiffness of the wedge-shaped structure 140 is 6.5 msi. The stiffness of the wedge-shaped structure 140 is substantially the same as the stiffness of the tank 120 and / or the tank skirt 110, which allows the wedge-shaped structure 140 to be formed of a material similar to the tank 120 and / or the tank skirt 110, which can use a cheaper material than a dedicated low-temperature softening strip. Figure 1 The softening strip described in has a stiffness value several orders of magnitude lower than the tank, for example, 0.1 msi.

[0051] The wedge-shaped structure 140 is bonded to both the tank 120 and the tank skirt 110 by the adhesive 130 . Figure 4The size of the adhesive 130 in the figure is exaggerated and is not necessarily to scale in order to clearly illustrate the adhesive 130. The adhesive 130 is a glue or a film adhesive. As shown in the figure, in some examples, the adhesive 130 extends beyond the end of the wedge-shaped structure 140. The adhesive 130 extends beyond the end of the wedge-shaped structure 140 at the open end of the y-shaped connection 102 and at the closed end (or sometimes referred to as the hook) of the y-shaped connection 102, so that the adhesive 130 also at least partially adheres the tank skirt 110 directly to the outer cylindrical surface 122 of the tank 120. The hook is filled with additional adhesive 130 to ensure that separation does not occur between the tank 120 and the tank skirt 110 at the termination of the wedge-shaped structure 140.

[0052] In addition to the wedge-shaped structure 140, the gradual reduction in the wall thickness of the tank 120 also helps to reduce stress concentration. The wall thickness of the tank 120 increases at the y-connection 102. As shown, the wall thickness 127 of the wall defining the cylindrical surface 122 of the tank 120 increases to the wall thickness 129 of the wall defining the dome end 124. Therefore, the wall thickness 129 of the tank 120 is greater at the y-connection 102 than at the cylindrical surface 122. The thickness of the wall gradually decreases or decreases again from the y-connection 102 toward the dome end 124 point, so that the wall thickness of the dome end 124 away from the y-connection 102 is equal to or much less than the wall thickness of the wall defining the cylindrical surface 122. The tapering of the wall thickness at the y-connection 102 makes the tank 120, the wedge-shaped structure 140 and the tank skirt 110 structurally sound at locations 107, 109 where stress concentration is prone to occur. Without the wedge, there would be a detrimental stress concentration at 102. However, with the wedge, the stress concentration is distributed between points 107 and 109. By tapering the wall thickness, those stress concentrations can be further minimized. The tank wall thickness and the size (e.g., height and length) of the wedge structure 140 can be optimized or sized simultaneously depending on the application conditions of the structure 100.

[0053] The tank 120 may be constructed by laying down plies to create a tank wall thickness that tapers as the plies are added at the y-joint 102. The ply drop ratio varies depending on the application conditions of the structure 100, but in some examples, the tank stack should have a ply drop ratio of no less than 30:1.

[0054] In some examples, the taper occurs at the y-connection 102. In some examples, the taper occurs beyond each side of the y-connection 102, such that a greater thickness extends beyond the y-connection 102.

[0055] like Figure 4As shown, the tank wall thickness gradually decreases, while the thickness of the tank skirt wall remains constant. However, in other examples, the thickness of the tank skirt wall defining the y-connection 102 gradually decreases. That is, the wall thickness of the wall of the tank skirt 110 gradually decreases at a greater thickness at the y-connection 102, and the wall thickness of the tank 120 remains constant. The thickness on either side of the y-connection 102 gradually decreases depending on the application conditions. In some examples, the wall thickness of the tank 120 and the tank skirt 110 defines that both sides of the y-connection 102 gradually decrease. That is, the thickness of the tank wall and the tank skirt wall both gradually decrease, while the thickness of the wall at the y-connection 102 is greater.

[0056] Depending on the application, various forces or loads may be imposed on structure 100 . Figure 4 Depicted is the skirt load 116 as opposed to the tank dome load 126. The varying loads will contribute to stress concentrations 107, 109 at the y-connection 102 and will affect the wall thickness taper and wedge 140 sizing requirements.

[0057] The gradual reduction in thickness allows for gradual sharing of the load between the tank 120 and the tank skirt 110 by maintaining an appropriate thickness at at least one side of the y-shaped connection 102 or both sides of the y-shaped connection 102 .

[0058] Reference now Figure 5 , which shows a perspective view of a can 120. The can 120 includes an outer cylindrical surface 122 and a rounded end 124. Also depicted is an adhesive 130 placed around the circumference of the can 120. The adhesive 130 extends onto the outer cylindrical surface 122 and onto the rounded end 124 for a length greater than the length of the location where the wedge-shaped structure will be placed. Figure 5 An axial direction 121 of the tank 120 is further depicted.

[0059] Reference now Figure 6 , which shows a close-up view of the can 120 and the adhesive 130. Figure 6 A cross section of the tank wall is further depicted. As discussed in other examples, the tank wall has a thickness that tapers to a greater thickness at the y-joint region (indicated by arrow 129) than it does closer to the top of the dome end (indicated by arrow 127). Still referring to Figure 6 In some examples, tank 120 is cured prior to applying adhesive 130 .

[0060] refer to Figure 7 , then the wedge-shaped structure 140 is laid on the adhesive 130 around the circumference of the can 120. Fig.11 , the wedge-shaped structure 140 is formed by fabric plies 142 having varying lengths, thereby allowing a generally triangular shape to occur. The length 144 of the wedge-shaped structure 140 and the height 146 of the wedge-shaped structure 140 can be customized as desired.

[0061] In some examples, the plies are fabric plies 142. In other examples, the plies are ribbon plies. Fig.11 , each fabric ply has an orientation that is different from the orientation of the fabric plies above and / or below. Figure 7 , an orientation of the fabric ply at zero degrees relative to the axial direction of the tank is generally shown at 147. An orientation of the fabric ply at forty-five degrees relative to the axial direction of the tank is generally shown at 149.

[0062] Can include Figure 7 The orientation of the fabric ply 142 can be adjusted at any angle including the angle between the two angles shown in . In some examples, the fabric ply 142 closest to the adhesive layer 130 is typically laid at forty-five degrees. Testing has shown that this orientation reduces the bond interface stiffness along the load direction (which may be parallel to the axial direction 121).

[0063] In some examples, the stack of wedge-shaped structures 140 is configured such that a first fabric ply 142 of the wedge-shaped structure 140 is oriented in a different direction than a second fabric ply 142 adjacent to the first fabric ply 142. In some examples, the orientation of the individual fabric plies 142 of the wedge-shaped structure 140 are laid in an alternating or ordered pattern, varying from forty-five degrees relative to the axial direction 121 of the tank 120 to zero degrees relative to the axial direction 121 of the tank 120. In some embodiments, the orientation alternates between two orientations.

[0064] In other embodiments, the orientation varies in a predetermined sequence of orientations. For example, in some embodiments, the orientation of the fabric plies 142 can be ordered so that two-thirds of the fabric plies are oriented at forty-five degrees and one-third of the fabric plies are oriented at zero degrees.

[0065] Reference again Figure 7 After laying the wedge-shaped structure 140, the wedge-shaped structure 140 is cured to form a composite material. In some examples, the wedge-shaped structure 140 is the same material as the tank 120. In some examples, the wedge-shaped structure 140 is similar to the material of the tank 120. In some examples, they are the same material in a different form, where the tank 120 is composed of tape and the wedge-shaped structure 140 is composed of fabric.

[0066] Reference now Figure 8 , adhesive 130 is applied to the wedge-shaped structure 140 and extends to the outer cylindrical surface of the tank 120. The adhesive 130 will be used to bond the wedge-shaped structure 140 to the tank skirt 110, and the outer cylindrical surface of the tank 120 to the tank skirt 110.

[0067] Reference now Fig. 9, the tank skirt 110 is laid over the adhesive 130 and the wedge-shaped structure 140. The tank skirt 110 extends beyond the wedge-shaped structure 140 and forms one side of the Y-shaped connection portion 102. Fig.10 , which shows a perspective view of a tank 120 and a tank skirt 110. As shown, the tank skirt 110 extends beyond only one domed end 124 of the tank 120. In some examples, the tank skirt 110 extends beyond both domed ends 124 of the tank 120, so that two y-shaped connecting portions 102 are formed between the tank 120 and the tank skirt 110, one y-shaped connecting portion 102 on each domed end 124 of the tank 120.

[0068] The examples disclosed herein utilize a third member, a wedge structure 140, at the joint between two load-bearing walls, the tank 120 and the tank skirt 110. The size and layup of the wedge structure 140 can be optimized in conjunction with the thickness of the adjacent walls to make the joint work. Such examples do not require the use of special materials. The stiffness of the wedge structure 140 can be made of composite material layers that are the same or very similar to the layers of the two main adjacent walls of the structural joint. Using materials similar to the adjacent wall materials produces similar thermal expansion coefficients, which helps to avoid harmful stresses due to thermal contraction / expansion. Any stiffness adjustments of the wedge structure 140 can be achieved by appropriate layer orientation and size and shape of the wedge structure 140. The stiffness of the wedge structure 140 is comparable to that of the adjacent walls, so that it also bears a large load and therefore has the function of converting one high stress concentration into two lower intensity stress concentrations.

[0069] In addition to introducing a wedge-shaped structure 140 of similar materials, the examples described herein also achieve appropriate load sharing between two load-bearing walls by gradually increasing and / or decreasing the thickness of one wall relative to the other wall so that the ratio of load sharing at the point where the two walls are connected does not harm the joint.

[0070] Reference now Fig.12 , which shows an example of method 500. Method 500 includes laying 502 a wedge-shaped structure at the domed end of a composite tank that has been cured. At 504, method 500 includes curing the wedge-shaped structure. The method also includes laying a tank skirt around the wedge-shaped structure and the tank at 506, wherein the wall of the tank and the wall of the tank skirt form two sides of a y-shaped connection between the tank and the tank skirt. The tank includes a gradually decreasing wall thickness with a larger thickness at the y-shaped connection. The method then ends.

[0071] In some examples, the method further includes adjusting the length and height of the wedge structure and the thickness of the tank at the y-connection simultaneously. Depending on the use parameters of the structure, the size of the wedge structure and the taper ratio of the tank wall or tank skirt wall can be optimized while minimizing the amount of material required and the total weight of the structure. Considerations include the pressure in the tank and the ambient pressure on the tank skirt.

[0072] In some examples, the method includes laying an adhesive layer on the tank before laying the wedge structure. In some examples, laying the wedge structure includes laying a fabric ply. The fabric ply includes an orientation. In some examples, the orientation of the fabric ply adjacent to the adhesive layer is at an angle relative to the axial direction of the tank. In some embodiments, the orientation of the fabric ply adjacent to the adhesive layer is forty-five degrees relative to the axial direction of the tank. In some examples, the orientation of the fabric ply adjacent to the adhesive layer is between five and eighty-five degrees relative to the axial direction of the tank. The angled fabric ply at the bonding interface between the wedge structure and the tank reduces the bonding interface stiffness in the load direction.

[0073] In some examples, the orientation of the individual fabric plies of the wedge-shaped structure is laid in an alternating or ordered pattern, varying from forty-five degrees relative to the axial direction of the tank to zero degrees relative to the axial direction of the tank. In some embodiments, the orientation may alternate. In other embodiments, the orientation varies in another predetermined order.

[0074] In some examples, the method includes laying up a tank skirt around the wedge-shaped structure, and the tank further includes tapering the tank skirt thickness with a greater wall thickness at the y-shaped connection.

[0075] Although described in the order depicted, the method may be performed in any of a variety of ordered combinations.

[0076] In the above description, certain terms may be used, such as "upper", "lower", "upper", "lower", "horizontal", "vertical", "left", "right", "above", "below", etc. These terms are used to provide some clear description when dealing with relative relationships when applicable. However, these terms are not intended to imply absolute relationships, positions and / or orientations. For example, with respect to an object, a "upper" surface can become a "lower" surface by simply turning the object over. Despite this, it is still the same object. In addition, unless otherwise expressly stated, the terms "include", "comprise", "have" and their variations mean "including but not limited to". Unless otherwise expressly stated, an enumerated list of items does not mean that any or all of the items are mutually exclusive and / or mutually inclusive. Unless otherwise expressly stated, the terms "one", "an" and "the" also refer to "one or more". In addition, the term "multiple" can be defined as "at least two".

[0077] In addition, examples of an element "coupled" to another element in this specification may include direct and indirect coupling. Direct coupling may be defined as an element coupling to another element and forming some contact therewith. Indirect coupling may be defined as a coupling between two elements that are not in direct contact with each other but have one or more additional elements between the coupled members. In addition, as used herein, fixing an element to another element may include direct fixing and indirect fixing. In addition, as used herein, "immediately adjacent to" does not necessarily mean contact. For example, an element may be in close proximity to another element without being in contact with the element.

[0078] As used herein, the phrase "at least one" when used with a list of items means that different combinations of one or more of the listed items may be used, and only one of the items in the list may be required. The item may be a specific object, thing, or category. In other words, "at least one" means that any combination of items or multiple items may be used from the list, but not all items in the list may be required. For example, "at least one of item A, item B, and item C" may mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, "at least one of item A, item B, and item C" may be, for example, but not limited to, two items in item A, one item in item B, and ten items in item C; four items in item B and seven items in item C; and other suitable combinations.

[0079] Unless otherwise indicated, the terms "first", "second", etc. are used herein merely as labels and are not intended to impose order, position, or hierarchy requirements on the items to which these terms refer. In addition, reference to an item such as "second" does not require or exclude the presence of an item such as "first" or lower numbered and / or an item such as "third" or higher numbered.

[0080] As used herein, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is actually capable of performing the specified function without any changes, rather than merely having the potential to perform the specified function after further modification. In other words, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is specifically selected, created, implemented, utilized, programmed, and / or designed to perform a specified function in order to perform the specified purpose. As used herein, "configured to" means an existing characteristic of a system, device, structure, article, element, component, or hardware that enables the system, device, structure, article, element, component, or hardware to perform the specified function without further modification. For the purposes of this disclosure, a system, device, structure, article, element, component, or hardware that is described as "configured to" perform a particular function may additionally or alternatively be described as "adapted to" and / or "operable to" perform that function.

[0081] The schematic flow charts included herein are generally described as logic flow charts. In this way, the depicted order and the steps of the mark indicate an example of the proposed method. Other steps and methods that are equivalent to one or more steps or parts thereof of the method shown in function, logic or effect can be envisioned. In addition, the format and symbols adopted are provided to explain the logical steps of the method, and are understood to not limit the scope of the method. Although various arrow types and line types can be adopted in the flow chart, they should be understood to not limit the scope of the corresponding method. In fact, some arrows or other connectors can be used to indicate only the logical flow of the method. For example, an arrow can indicate a waiting or monitoring period of unspecified duration between the enumerated steps of the depicted method. In addition, the order of occurrence of a particular method may strictly follow or may not strictly follow the order of the corresponding steps shown.

[0082] In addition, this disclosure includes examples according to the following clauses:

[0083] Clause 1. A structure for containing a substance, the structure comprising:

[0084] a can (120) comprising an outer cylindrical surface (122) and a domed end (124); and

[0085] a tank skirt (110) disposed circumferentially around the tank (120), wherein the wall of the tank (120) and the wall of the tank skirt (110) form two sides of a Y-shaped connection (102) between the tank (120) and the tank skirt (110);

[0086] in:

[0087] The Y-shaped connection (102) includes a wedge-shaped structure (140) placed between the tank (120) and the tank skirt (110); and

[0088] The thickness of at least one of the walls of the tank (120) or the tank skirt (110) forming the Y-shaped connection portion (102) gradually decreases, so that the gradually decreasing thickness of at least one of the walls of the tank (120) or the tank skirt (110) has a greater thickness at the Y-shaped connection portion (102) than away from the Y-shaped connection portion (102).

[0089] Clause 2. The structure according to clause 1, wherein the thickness of the wall of the tank (120) forming the Y-shaped connection (102) gradually decreases.

[0090] Clause 3. A structure according to clause 1 or 2, wherein the thickness of the wall of the tank (120) forming the y-shaped connection (102) is greater along the length of the y-shaped connection (102) and the length extending beyond each side of the y-shaped connection (102) than the thickness away from the y-shaped connection (102).

[0091] Clause 4. A structure as described in any of Clauses 1-3, wherein:

[0092] The tank (120) comprises a stack of plies; and

[0093] The layer reduction rate of the stacked layers of the board layers along the Y-shaped connecting portion (102) is not less than 30:1.

[0094] Clause 5. The structure according to any one of clauses 1 to 4, wherein the thickness of the wall of the tank skirt (110) forming the Y-shaped connecting portion (102) gradually decreases.

[0095] Clause 6. The structure of clause 5, wherein the thickness of the wall of the tank skirt (110) forming the y-shaped connection (102) is greater along the length of the y-shaped connection (102) and the length extending beyond each side of the y-shaped connection (102) than the thickness away from the y-shaped connection (102).

[0096] Clause 7. The structure of any of clauses 1-6, wherein the stiffness of the wall of the tank (120) is substantially the same as the stiffness of the wedge-shaped structure (140).

[0097] Clause 8. A structure as described in any of Clauses 1 to 7, wherein:

[0098] The thickness of the wall of the tank (120) forming the Y-shaped connection (102) gradually decreases; and

[0099] The thickness of the wall of the tank skirt (110) forming the Y-shaped connecting portion (102) gradually decreases.

[0100] Clause 9. A structure as described in any of Clauses 1 to 8, wherein:

[0101] The tank (120) and the wedge-shaped structure (140) are made of different forms of materials from the same series of composite materials;

[0102] The tank (120) includes a belt; and

[0103] The wedge-shaped structure (140) comprises a fabric.

[0104] Clause 10. The structure of clause 9, wherein the stack of wedge-shaped structures (140) is configured such that a first fabric ply (142) of the wedge-shaped structures (140) is oriented in a different direction than a second fabric ply (142) adjacent to the first fabric ply (142).

[0105] Clause 11. The structure of clause 10, wherein the fabric ply (142) closest to the tank (120) is oriented at forty-five degrees relative to an axial direction of the tank (120).

[0106] Clause 12. The structure of any of clauses 1-11, wherein the tank (120) is a pressurized container.

[0107] Clause 13. The structure of any of clauses 1-12, wherein the tank (120) is a composite cryogenic fuel tank.

[0108] Clause 14. A structure as described in any of clauses 1 to 13, wherein the structure forms part of a spacecraft.

[0109] Clause 15. A structure for containing a pressurized substance, the structure comprising:

[0110] a pressurized tank (120) comprising an outer cylindrical surface (122) and a domed end (124); and

[0111] a tank skirt (110) disposed circumferentially around the pressurized tank (120), wherein the wall of the pressurized tank (120) and the wall of the tank skirt (11) form two sides of a Y-shaped connection (102) between the pressurized tank (120) and the tank skirt (110);

[0112] in:

[0113] The Y-shaped connection (102) includes a wedge-shaped structure (140) placed between the pressurized tank (120) and the tank skirt (110);

[0114] The thickness of the wall of the pressurized tank (120) forming the Y-shaped connecting portion (102) gradually decreases, so that the wall thickness of the pressurized tank (120) at the Y-shaped connecting portion (102) is greater than the wall thickness away from the Y-shaped connecting portion (102);

[0115] The wedge-shaped structure (140) comprises a stack of multiple fabric plies; and

[0116] The stack of multiple fabric plies of the wedge-shaped structure (140) includes a first fabric ply and a second fabric ply, the second fabric ply being oriented in a different direction than the first fabric ply.

[0117] Clause 16. The structure of clause 15, wherein:

[0118] The first fabric ply is closer to the pressurized tank (120) than the second fabric ply; and

[0119] The first fabric ply is oriented at forty-five degrees relative to an axial direction of the tank (120).

[0120] Clause 17. A method (500) of integrating a tank skirt (110) and a tank (120), each of the tank skirt (110) and the tank (120) being made of a composite material, the method comprising:

[0121] After the tank (120) has cured, laying (502) a wedge-shaped structure (140) at a tapered thickness portion of a rounded end (124) of the tank (120);

[0122] curing (504) the wedge-shaped structure (140) after the wedge-shaped structure (140) is laid at the domed end (124) of the tank (120); and

[0123] After the wedge-shaped structure (140) is cured, the tank skirt (110) is laid (506) around the wedge-shaped structure (140) and the tank (120) so that the wall of the tank (120) and the wall of the tank skirt (110) form two sides of a Y-shaped connection (102) between the tank (120) and the tank skirt (110), and the wedge-shaped structure (140) is located on both sides.

[0124] Clause 18. The method (500) of clause 17, wherein the step of laying the wedge-shaped structure includes orienting a first fabric ply (142) of the wedge-shaped structure (140) in a direction different from the direction of a second fabric ply (142) adjacent to the first fabric ply (142).

[0125] Clause 19. The method (500) of clause 17 or 18, wherein the fabric ply (142) of the wedge-shaped structure (140) closest to the tank (120) is oriented at forty-five degrees relative to an axial direction of the tank (120).

[0126] Clause 20. The method (500) of any of clauses 17-19, wherein laying the tank skirt (110) around the wedge-shaped structure (140) and the tank (120) further comprises gradually reducing the thickness of the tank skirt (110) such that the thickness of the tank skirt (110) is greater at the Y-shaped connection (102) than at a location away from the Y-shaped connection (102).

[0127] Without departing from the spirit or essential features of the present invention, the subject matter may be implemented in other specific forms. The described examples should be considered in all respects as illustrative and non-restrictive. All changes falling within the equivalent meaning and scope of the technical solution should be included within its scope.

Claims

1. A structure for containing a substance, the structure comprising: A tank (120) comprising an outer cylindrical surface (122) and a domed end (124); as well as a tank skirt (110) disposed circumferentially around the tank (120), wherein the wall of the tank (120) and the wall of the tank skirt (110) form two sides of a Y-shaped connection (102) between the tank (120) and the tank skirt (110); in: The Y-shaped connection (102) includes a wedge-shaped structure (140) placed between the tank (120) and the tank skirt (110); and The thickness of at least one of the wall of the tank (120) or the wall of the tank skirt (110) forming the Y-shaped connection portion (102) is gradually reduced, so that the gradually reduced thickness of at least one of the wall of the tank (120) or the wall of the tank skirt (110) has a greater thickness at the Y-shaped connection portion (102) than away from the Y-shaped connection portion (102), The tank (120) comprises a first stack of plies, The tank skirt (110) comprises a second stack of plies, The wedge-shaped structure (140) comprises a third stack of plies, wherein the third stack of plies comprises a first fabric ply and a second fabric ply adjacent to the first fabric ply, the first fabric ply of the third stack of plies being oriented in different directions than the second fabric ply of the third stack of plies.

2. The structure according to claim 1, wherein: The thickness of the wall of the tank (120) forming the Y-shaped connection (102) gradually decreases.

3. The structure according to claim 2, wherein: The wall of the tank (120) forming the y-shaped connection (102) has a thickness greater along the length of the y-shaped connection (102) and the length extending beyond each side of the y-shaped connection (102) than away from the y-shaped connection (102).

4. The structure according to claim 3, wherein: The layer reduction rate of the first stack of plate layers along the Y-shaped connecting portion (102) is not less than 30:

1.

5. The structure according to any one of claims 1 to 4, wherein: The thickness of the wall of the tank skirt (110) forming the Y-shaped connecting portion (102) gradually decreases.

6. The structure according to claim 5, wherein: The thickness of the wall of the tank skirt (110) forming the y-shaped connection (102) is greater along the length of the y-shaped connection (102) and the length extending beyond each side of the y-shaped connection (102) than away from the y-shaped connection (102).

7. The structure according to any one of claims 1 to 4, wherein: The rigidity of the wall of the tank (120) is the same as the rigidity of the wedge-shaped structure (140).

8. The structure according to any one of claims 1 to 4, wherein: The thickness of the wall of the tank (120) forming the Y-shaped connection (102) gradually decreases; and The thickness of the wall of the tank skirt (110) forming the Y-shaped connecting portion (102) gradually decreases.

9. The structure according to any one of claims 1 to 4, wherein: The tank (120) and the wedge-shaped structure (140) are made of different forms of materials from the same series of composite materials; The tank (120) includes a belt; and The wedge-shaped structure (140) comprises fabric.

10. The structure according to claim 1, wherein: The fabric ply (142) closest to the tank (120) is oriented at forty-five degrees relative to the axial direction of the tank (120).

11. The structure according to claim 1, wherein: The tank is a pressurized container.

12. The structure according to claim 1, wherein: The tank is a composite cryogenic fuel tank.

13. The structure according to claim 1, wherein: The structure forms a part of a spacecraft.

14. A structure for containing a pressurized substance, the structure comprising: A pressurized tank including an outer cylindrical surface and a domed end; as well as a tank skirt disposed circumferentially around the pressurized tank, wherein the wall of the pressurized tank and the wall of the tank skirt form two sides of a y-shaped connection between the pressurized tank and the tank skirt; in: The Y-shaped connection includes a wedge-shaped structure placed between the pressurized tank and the tank skirt; The thickness of the wall of the pressurized tank forming the Y-shaped connection portion gradually decreases, so that the thickness of the wall of the pressurized tank at the Y-shaped connection portion is greater than the thickness away from the Y-shaped connection portion; The wedge-shaped structure comprises a stack of a plurality of fabric plies; and The stack of multiple fabric plies of the wedge-shaped structure includes a first fabric ply and a second fabric ply, the second fabric ply being oriented in a different direction than the first fabric ply, The tank (120) comprises a first stack of plies, The tank skirt (110) comprises a second stack of plies, The wedge-shaped structure (140) comprises a third stack of plies, wherein the third stack of plies comprises a first fabric ply and a second fabric ply adjacent to the first fabric ply, the first fabric ply of the third stack of plies being oriented in different directions than the second fabric ply of the third stack of plies.

15. The structure of claim 14, wherein: the first fabric ply is closer to the pressurized tank than the second fabric ply; and The first fabric ply is oriented at forty-five degrees relative to an axial direction of the tank.

16. A method (500) of integrating a tank skirt (110) and a tank (120), each of the tank skirt (110) and the tank (120) being made of a composite material, the method comprising: After the tank (120) has cured, laying (502) a wedge-shaped structure (140) at the tapered thickness portion of the rounded end (124) of the tank (120); curing (504) the wedge-shaped structure (140) after the wedge-shaped structure (140) is laid at the domed end (124) of the tank (120); and After curing the wedge-shaped structure (140), laying (506) the tank skirt (110) around the wedge-shaped structure (140) and the tank (120) so that the wall of the tank (120) and the wall of the tank skirt (110) form two sides of a Y-shaped connection (102) between the tank (120) and the tank skirt (110), and the wedge-shaped structure (140) is located between the two sides, The tank (120) comprises a first stack of plies, The tank skirt (110) comprises a second stack of plies, The wedge-shaped structure (140) comprises a third stack of plies, wherein the third stack of plies comprises a first fabric ply and a second fabric ply adjacent to the first fabric ply, the first fabric ply of the third stack of plies being oriented in different directions than the second fabric ply of the third stack of plies.

17. The method (500) of claim 16, wherein: The fabric ply (142) of the wedge-shaped structure (140) closest to the tank (120) is oriented at forty-five degrees relative to the axial direction of the tank (120).

18. The method (500) of claim 16, wherein: Laying the tank skirt (110) around the wedge-shaped structure (140) and the tank (120) also includes gradually reducing the thickness of the tank skirt (110) so that the thickness of the tank skirt (110) is greater at the Y-shaped connection (102) than at a location away from the Y-shaped connection (102).

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