Stamping type thin plate storage tank short shell structure for carrier rocket propellant storage tank

Abstract

The invention discloses a ram-type thin plate storage tank short shell structure for a carrier rocket propellant storage tank, and belongs to the field of aerospace manufacturing. Comprising a short shell body, the short shell body is made of a stainless steel sheet, and main reinforcing ribs and auxiliary reinforcing ribs are integrally formed on the inner surface and the outer surface of the short shell body through a high-precision multi-direction force application overall stamping process to form a gradient rigidity transition structure; the main reinforcing rib is a semicircular channel with the groove width to depth ratio of 4.7: 1, and the end part of the main reinforcing rib is provided with a hemispherical end to reduce stress concentration; a smooth straight section area conformal with the barrel section is reserved at the lower end of the short shell and serves as an integrated welding connector, and the structural design and stamping parameters are subjected to finite element simulation optimization. The mass of the structure only accounts for 8%-10% of the whole storage tank, the lightweight effect is remarkable, force transmission is continuous and efficient, the rigidity and buckling resistance are greatly improved, welding and assembling time is shortened, the manufacturing cost is reduced, the period is shortened, the assembling and butt joint precision is high, and the structure is suitable for large spaceflight thin-wall structures such as carrier rocket propellant storage tanks.

Description

Technical Field

[0001] This invention belongs to the technical field of aerospace manufacturing, specifically relating to a stamped thin-plate short-shell structure for a propellant tank of a launch vehicle. Background Technology

[0002] As the core load-bearing component connecting the tank bottom and the cylindrical section, the rocket propellant tank short shell plays a crucial role in transmitting concentrated axial loads and maintaining structural continuity.

[0003] Currently, high-performance short shells are mostly manufactured using composite materials, but this process is complex, has a long molding cycle, and is costly. To reduce manufacturing costs, existing technologies also employ short shell structures made by welding together bent corrugated stainless steel plates. While this approach addresses the economic and manufacturability issues of composite material short shells to some extent, it still has significant drawbacks: First, the corrugated plate short shell and the tank section are mechanically connected by an outward-facing frame, resulting in inconsistent force transmission paths and additional bending moments. This leads to localized stress concentration and affects the overall load-bearing capacity of the tank. Second, the structure requires extensive welding, resulting in numerous and long welds. This significantly increases assembly and welding costs and introduces welding deformation and residual stress due to heat input. Third, the additional mass accumulation from welding materials significantly increases the structural redundancy, contradicting the lightweight design goals of spacecraft. Fourth, the overall stiffness and stability are insufficient. The corrugated plate structure has weak bending stiffness in its non-primary load-bearing directions. To ensure overall stability and prevent buckling, the plate thickness often needs to be increased, further reducing its lightweight potential. These shortcomings collectively restrict the performance and economy of the short tank shell in launch vehicles.

[0004] Therefore, there is an urgent need to develop a new type of stamped thin-plate storage tank structure that balances manufacturing cost and process feasibility, features a continuous force transmission path, high structural efficiency, and lightweight properties. Summary of the Invention

[0005] This invention provides a stamped thin-plate short-shell structure for propellant tanks of launch vehicles. The structure forms reinforcing ribs on the inner and outer surfaces of the short shell body through an integral stamping process, replacing the traditional composite material or stainless steel welded corrugated plate short shell. This design effectively overcomes the limitations of composite material short shells, such as complex processes, high costs, and long manufacturing cycles, while solving the problems of discontinuous force transmission paths, excessive welds, large redundant mass, and insufficient rigidity of stainless steel corrugated plate short shells.

[0006] This invention provides a stamped thin-plate short-shell structure for a propellant tank of a launch vehicle. The short-shell structure connects the tank bottom and the cylindrical section, and includes a short-shell body made of stainless steel sheet. Several reinforcing ribs are integrally formed on the inner and outer surfaces of the short-shell body through an integral stamping process. The lower end of the short-shell body retains a smooth, straight section that is not stamped. The outer surface of the smooth, straight section is configured to conform to the outer surface of the cylindrical section, serving as an integral welding interface with the tank bottom. The reinforcing rib structure includes main reinforcing ribs and auxiliary reinforcing ribs. The number of auxiliary reinforcing ribs is half the number of reinforcing ribs, and the auxiliary reinforcing ribs are located on the outer side of the ends of the main reinforcing ribs, forming a gradient stiffness transition structure.

[0007] Preferably, the cross-section of the main reinforcing rib is a semi-circular channel, and the ends of the main reinforcing rib all end in a hemispherical shape.

[0008] Preferably, the ratio of the width to the depth of the semi-circular channel is 4.7:1.

[0009] Preferably, the auxiliary reinforcing ribs include concave short reinforcing ribs and convex long reinforcing ribs, wherein the short and long reinforcing ribs are thin-walled semi-circular reinforcing ribs.

[0010] Preferably, the short shell body is spot-welded to the thickened section of the storage tank section via long reinforcing ribs; an end frame is provided at one end of the short shell body near the short reinforcing ribs.

[0011] Preferably, the mass of the short shell body accounts for 8% to 10% of the total mass of the storage tank.

[0012] Preferably, the stainless steel sheet has a wall thickness of 1.5 mm.

[0013] Preferably, during the structural design of the short shell body, the mechanical response of the short shell body under axial compression, internal compression and bending moment conditions is accurately simulated by the finite element method of static strength analysis and explicit dynamic analysis, so as to deterministically identify the stiffness weak area and stress concentration area of ​​the short shell body.

[0014] Preferably, the overall stamping process is a high-precision, multi-directional force stamping process, and the pressure and speed parameters during the stamping process are set and optimized based on the results of finite element forming simulation.

[0015] The beneficial effects of this invention are: (1) Significant weight reduction effect, meeting the needs of aerospace design: The present invention uses stainless steel thin plate as the main body of the short shell, and replaces the traditional welded corrugated plate with a reinforcing rib structure formed by integral stamping, avoiding the redundant mass caused by a large number of welds, so that the mass of the main body of the short shell accounts for only 8%~10% of the total mass of the tank; while ensuring structural strength and rigidity, the overall weight of the tank is greatly reduced, directly improving the effective payload capacity and propulsion efficiency of the launch vehicle.

[0016] (2) Continuous and efficient force transmission path, significantly improved load-bearing capacity: Through the gradient stiffness transition structure (main stiffener + auxiliary stiffener), the hemispherical end design of the main stiffener, and the conformal docking design of the smooth straight section area with the tank bottom and cylinder section, the problems of discontinuous force transmission path and stress concentration caused by additional bending moment in traditional stainless steel corrugated plate short shells are solved; the force flow can be smoothly diffused from the main body of the short shell through the main stiffener and auxiliary stiffener, and then efficiently transmitted to the tank bottom and cylinder section through the integrated welding interface, which significantly improves the overall load-bearing capacity and stability of the structure under axial compression, internal pressure and bending moment combined loads, and avoids the risk of local failure.

[0017] (3) Reduced manufacturing costs and shortened production cycle: This invention replaces expensive composite materials with low-cost stainless steel sheets, eliminating the complex process of composite material layup-autoclave curing; in addition, the integral stamping process eliminates a large amount of welding work in traditional welded structures, reducing the time cost of assembly and welding; at the same time, the stamping process is highly automated and has a short process, avoiding the long curing cycle of composite materials or the cumbersome assembly, positioning and welding time of multiple corrugated plates, which significantly improves production efficiency and manufacturing consistency.

[0018] (4) High process reliability and product consistency: integral stamping avoids a large amount of manual welding work, reduces process defects such as deformation and residual stress caused by heat input, and improves the consistency and reliability of product quality; the standardized geometric configuration of the main reinforcing rib, the gradient layout of the auxiliary reinforcing rib, and the parameter optimization based on finite element simulation further ensure the consistency of product manufacturing and reduce the risk of batch differences. Attached Figure Description

[0019] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the short-shell main body connecting the storage tank structure of the present invention; Figure 2 This is a schematic diagram of the short shell main structure of the present invention; Figure 3 This is a cross-sectional view of the short-shell main body connecting the storage tank structure of the present invention.

[0021] In the picture: 1-Box bottom; 2-Cylinder section; 21-Thickened area of ​​cylinder section; 3-Short shell body; 31-Main reinforcing rib; 32-Auxiliary reinforcing rib; 321-Short reinforcing rib; 322-Long reinforcing rib; 33-End frame. Detailed Implementation

[0022] The following are specific embodiments of the present invention described in conjunction with the accompanying drawings, further illustrating the technical solutions of the present invention. However, the present invention is not limited to these embodiments. Specific details, such as particular configurations and components, are provided in the following description merely to aid in a comprehensive understanding of the embodiments of the present invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Furthermore, for clarity and brevity, descriptions of known functions and structures have been omitted.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0024] like Figures 1-3 As shown, this invention provides a stamped thin-plate short-shell structure for a propellant tank of a launch vehicle, used to connect the tank bottom 1 and the cylindrical section 2. The short-shell structure includes a short-shell body 3, which is the core component bearing the main load. The short-shell body 3 can be made of various materials. As a preferred embodiment, the short-shell body 3 is made of stainless steel sheet with a wall thickness of 1.5mm, due to its good strength, toughness, corrosion resistance, and relatively low cost. To improve the rigidity and stability of the short-shell body 3, several reinforcing ribs are integrally formed on the inner and outer surfaces of the short-shell body 3 through an integral stamping process. The number and distribution of the reinforcing ribs can be adjusted according to specific load conditions and structural optimization objectives. The lower end of the short shell body 3 retains a smooth, straight section that is not stamped. The outer surface of this smooth, straight section is configured to conform to the outer surface of the cylindrical section 2, serving as an integrated welding interface with the tank bottom 1. This conformal design ensures the geometric continuity between the short shell structure and the cylindrical section 2, thereby achieving smooth load transfer. The integrated welding interface allows the short shell body 3 to be directly welded to the tank bottom 1, reducing the use of intermediate connecting parts and simplifying the assembly process. The reinforcing rib structure includes main reinforcing ribs 31 and auxiliary reinforcing ribs 32. The number of auxiliary reinforcing ribs 32 is half the number of reinforcing ribs in the overall structure, and the auxiliary reinforcing ribs 32 are located on the outer side of the ends of the main reinforcing ribs 31, forming a gradient stiffness transition structure. This layout helps to achieve smooth load diffusion from the short shell body 3 to the main reinforcing ribs 31, and then through the auxiliary reinforcing ribs 32, significantly improving the uniformity and continuity of force flow transmission, and increasing the fatigue life and overall load-bearing capacity of the structure.

[0025] Through the above technical solution, the stamped thin-plate tank short-shell structure of the present invention adopts stainless steel thin plates and integral stamping process to form reinforcing ribs, effectively avoiding the complex process and high cost of traditional composite material short shells, and overcoming the problems of discontinuous force transmission path, large welding volume, redundant mass and insufficient rigidity of stainless steel welded corrugated plate short shells. Therefore, it achieves efficient and continuous load transfer between the short shell body 3 and the cylindrical section 2, improves the overall rigidity and strength of the tank, and also has a lightweight effect, making it suitable for large aerospace thin-walled structures such as propellant tanks for launch vehicles.

[0026] This application further proposes that the main reinforcing rib 31 has a semi-circular channel cross-section, with each end of the main reinforcing rib 31 ending in a hemispherical tip. The width-to-depth ratio of the semi-circular channel is 4.7:1. Specifically, the structural design of this main reinforcing rib 31 has the following advantages: First, the geometric characteristics of the semi-circular channel allow the load to be distributed more evenly within the reinforcing rib and at the connection with the short shell body 3, avoiding stress peaks that are easily generated by rectangular or sharp-cornered reinforcing ribs, and minimizing the stress concentration factor. Second, the precise width-to-depth ratio ensures that the rib has excellent buckling stability and a high moment of inertia under load. Third, the smooth spherical transition greatly reduces the demolding resistance and springback effect of the mold, ensuring the feasibility and yield of the one-time integral stamping process. This optimized reinforcing rib structure, while maintaining the stiffness provided by the original reinforcing rib, greatly improves the structural integrity and fatigue life of the short shell body 3 under complex working conditions such as axial compression, internal pressure, and bending moment, thereby improving the overall reliability and safety of the launch vehicle propellant tank.

[0027] This application further proposes auxiliary reinforcing ribs 32, including concave short reinforcing ribs 321 and convex long reinforcing ribs 322, both of which are thin-walled semi-circular ring reinforcing ribs. Specifically, the short reinforcing ribs 321 can be strategically placed in stress concentration areas or locations requiring rapid stiffness changes to effectively disperse local stress; the long reinforcing ribs 322 provide more continuous and uniform stiffness support, ensuring smooth load transfer on the short shell body 3. The geometry of the thin-walled semi-circular ring effectively controls structural weight and improves material utilization while ensuring sufficient bending and torsional stiffness. This gradient stiffness transition structure not only optimizes the mechanical response of the short shell body 3 and reduces the risk of stress concentration, but also improves the fatigue life and reliability of the overall structure, thereby effectively solving the problem of local stiffness mismatch that may be caused by improper design of the auxiliary reinforcing ribs 32 in the gradient stiffness transition.

[0028] This application further proposes a spot-welded connection between the short shell body 3 and the thickened section 21 of the tank section 2 via long reinforcing ribs 322; an end frame 33 is provided at the end of the short shell body 3 near the short reinforcing ribs 321. Specifically, the long reinforcing ribs 322, as part of the reinforcing structure of the short shell body 3, can effectively concentrate and transfer the load borne by the short shell body 3 to the connection point. At the same time, the thickened section 21 of the tank section 2 provides a more solid and load-bearing base for the connection, which can better disperse and absorb the local stress from the spot-welded connection, avoiding stress concentration in the weak area of ​​the section 2. The spot-welded connection method ensures the reliability and efficiency of the connection, while reducing the thermal impact on the thin-walled long reinforcing ribs 322 and the thickened section 21, thereby ensuring the structural integrity and fatigue life of the connection area. This connection method optimizes the load transfer path between the short shell body 3 and the tank section 2, significantly improving the overall stiffness and stability of the entire tank structure under complex working conditions such as axial compression, internal pressure, and bending moment.

[0029] This application further proposes that the mass of the short shell body 3 accounts for 8% to 10% of the total mass of the propellant tank. This precise mass control ensures that the short shell body 3 provides the necessary connection strength and stiffness (through its stainless steel sheet material, integral stamping reinforcing rib structure, and gradient stiffness transition design) while avoiding redundant mass caused by over-design. This not only helps to reduce the overall structural mass of the propellant tank, thereby directly improving the payload capacity and propulsion efficiency of the launch vehicle, but also ensures that the short shell structure has sufficient load-bearing capacity and stability under complex working conditions such as axial compression, internal pressure, and bending moment. It avoids structural failure or performance degradation problems that may be caused by excessive or insufficient mass, and achieves the best balance between structural performance and lightweight.

[0030] This application further proposes that, during the structural design of the short shell body 3, a finite element method combining static strength analysis and explicit dynamic analysis is used to accurately simulate the mechanical response of the short shell body 3 under axial compression, internal pressure, and bending moment conditions, definitively identifying the stiffness-weak areas and stress concentration regions of the short shell body 3. By introducing the finite element method combining static strength analysis and explicit dynamic analysis, the mechanical response of the short shell body 3 under various complex conditions such as axial compression, internal pressure, and bending moment can be accurately simulated. This allows for a systematic and comprehensive evaluation of the stress state of the short shell structure, enabling designers to definitively identify the stiffness-weak areas and stress concentration regions of the short shell body 3, thus providing a scientific basis for subsequent structural optimization. For example, the geometric parameters, layout, or local wall thickness of the stiffening rib structure (including the main stiffener 31 and auxiliary stiffener 32) can be adjusted to eliminate or alleviate stress concentration, improve overall stiffness, ensure the reliability and safety of the short shell structure under extreme load conditions, effectively avoid overall structural failure due to local failure, and significantly improve the service performance of the launch vehicle propellant tank.

[0031] This application further proposes a high-precision, multi-directional force-applying stamping process for the overall stamping process. The pressure and speed parameters during the stamping process are set and optimized based on the results of finite element forming simulation. By adopting a high-precision, multi-directional force-applying stamping process, the forming process of the stainless steel sheet can be precisely controlled, ensuring that the reinforcing rib structure on the short shell body 3, including the main reinforcing rib 31 and the auxiliary reinforcing rib 32, as well as the gradient stiffness transition structure, can be integrally formed with extremely high geometric accuracy and surface quality. At the same time, the pressure and speed parameters during the stamping process are set and optimized based on the results of finite element forming simulation, allowing potential forming defects, such as local material thinning, stress concentration, or springback, to be predicted and avoided before actual production. This not only significantly improves the forming quality and yield rate of the short shell structure, but also ensures that the short shell body 3 has excellent mechanical response and structural integrity under complex working conditions such as axial pressure, internal pressure, and bending moment, thereby effectively improving the overall reliability and safety of the launch vehicle propellant tank.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] In the description of this application, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

Claims

1. A stamped thin-plate short-shell structure for a propellant tank of a launch vehicle, the short-shell structure being used to connect the tank bottom (1) and the cylindrical section (2), characterized in that, Includes a short shell body (3), which is made of stainless steel sheet and has several reinforcing ribs integrally formed on the inner and outer surfaces of the short shell body (3) by an integral stamping process; The lower end of the short shell body (3) retains a smooth, straight section that is not stamped. The outer surface of the smooth, straight section is configured to conform to the outer surface of the cylindrical section (2) as an integrated welding interface with the bottom of the storage tank (1). The reinforcing rib structure includes a main reinforcing rib (31) and an auxiliary reinforcing rib (32). The number of auxiliary reinforcing ribs (32) is half the number of the reinforcing rib structure, and the auxiliary reinforcing ribs (32) are arranged on the outer side of the end of the main reinforcing rib (31) to form a gradient stiffness transition structure.

2. The stamped thin-plate short-shell structure for a propellant tank of a launch vehicle according to claim 1, characterized in that, The cross-section of the main reinforcing rib (31) is a semi-circular channel, and the ends of the main reinforcing rib (31) are all hemispherical ends.

3. A stamped thin-plate short-shell structure for a propellant tank of a launch vehicle according to claim 2, characterized in that, The width-to-depth ratio of the semi-circular channel is 4.7:

1.

4. A stamped thin-plate short-shell structure for a propellant tank of a launch vehicle according to claim 1, characterized in that, The auxiliary reinforcing rib (32) includes a concave short reinforcing rib (321) and a convex long reinforcing rib (322), wherein the short reinforcing rib (321) and the long reinforcing rib (322) are thin-walled semi-circular reinforcing ribs.

5. A stamped thin-plate short-shell structure for a propellant tank of a launch vehicle according to claim 4, characterized in that, The short shell body (3) is spot-welded to the thickened section (21) of the tank section (2) by a long reinforcing rib (322); the short shell body (3) has an end frame (33) at one end near the short reinforcing rib (321).

6. A stamped thin-plate short-shell structure for a propellant tank of a launch vehicle according to claim 1, characterized in that, The mass of the short shell body (3) accounts for 8% to 10% of the total mass of the storage tank.

7. A stamped thin-plate short-shell structure for a propellant tank of a launch vehicle according to claim 1, characterized in that, The stainless steel sheet has a wall thickness of 1.5 mm.

8. According to claim 1, a short shell structure for a stamped thin plate propellant tank for a launch vehicle is provided. In the structural design of the short shell body (3), the mechanical response of the short shell body (3) under axial compression, internal pressure and bending moment conditions is accurately simulated by the finite element method of static strength analysis and explicit dynamic analysis, and the stiffness weak area and stress concentration area of ​​the short shell body (3) are identified deterministically.

9. The short shell structure of a stamped thin plate propellant tank for a launch vehicle as described in claim 1, wherein the overall stamping process is a high-precision, multi-directional force-applying stamping process, and the pressure and speed parameters during the stamping process are set and optimized based on the results of finite element forming simulation.

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