A large lightweight high-strength high-rigidity vibration test tooling optimization design method

Abstract

The application provides a large-scale light-weight high-strength high-rigidity vibration test tool optimization design method, which comprises the following steps: completing initial sample design of the vibration test tool; adopting finite element simulation calculation to optimize size parameters of the vibration test tool; completing joint simulation of the vibration test tool and a connected product to complete structure and size checking of the vibration test tool.

Description

Technical Field

[0001] This invention belongs to the field of special material processing and induction heating technology, specifically relating to an optimized design method for a large, lightweight, high-strength, and high-rigidity vibration testing fixture. Background Technology

[0002] Launch vehicles experience complex and diverse vibration environments during flight, including steady-state vibration of rocket engines, boundary layer pulsating pressure, POGO vibration, tank liquid sloshing, and interstage separation. These vibrations severely impact the safety and normal operation of astronauts, instruments, equipment, launch vehicles, and upper stages. Reusable launch vehicles, in particular, experience even more severe vibration loads during recovery than during launch, necessitating ground-based mechanical environment testing. Sinusoidal and random vibrations are the most impactful mechanical environments, forming the basis for environmental adaptability design and verification. Vibration tests of single modules or assemblies often utilize real inertial navigation systems (INS) products and instruments, providing the closest possible verification to real-world conditions and effectively addressing safety margins and operational requirements during launch vehicle design.

[0003] The vibration test of the launch vehicle section uses a high-thrust electromagnetic vibration table for load loading. The key to the test lies in the vibration test boundary fixture. The vibration test boundary fixture must be compatible with the mechanical interface of the electromagnetic vibration table and the section interface to transfer vibration energy to the product without distortion. There are restrictions on the lowest frequency, number, and size of the resonance peaks, as well as the width of the 3dB resonance bandwidth. Since the mechanical interface of the electromagnetic vibration table is smaller than that of the section interface, the fixture is designed in a flowerpot shape. The large-diameter upper flange connects to the section product, and the small-diameter lower flange connects to the electromagnetic vibration table. The rotating wall connects the upper and lower flanges. The rotating wall is designed with reinforcing ribs to enhance strength and stiffness, and weight-reduction holes are designed on the rotating wall to facilitate weight reduction and measurement cable routing. The magnesium-aluminum alloy casting process is selected for processing, which can increase system damping and reduce the thrust loss of the electromagnetic vibration table.

[0004] Vibration tests on medium and heavy-lift rocket sections are characterized by the large mass, diameter, and height of the test product. Therefore, vibration testing requires vibration transfer fixtures with sufficient strength and stiffness to transfer the dynamic loads and withstand the reaction forces on the test system during product resonance. Currently, vibration fixtures designed using existing rocket section fixture design methods suffer from drawbacks such as large mass and low modal frequencies. This results in a large added mass to the test system and amplified coupling verification in the resonance region, making it impossible to conduct tests of the specified magnitude on the product. Summary of the Invention

[0005] The purpose of this invention is to overcome one of the problems existing in the prior art and provide an optimized design method for large, lightweight, high-strength, and high-rigidity vibration testing fixtures, which can be designed to meet the vibration test boundary requirements of medium and heavy rocket sections.

[0006] This invention provides an optimized design method for a large, lightweight, high-strength, and high-stiffness vibration testing fixture, comprising the following steps: Complete the initial design of the vibration test fixture; The dimensional parameters of the vibration test fixture were optimized using finite element simulation. Complete the joint simulation of the vibration test fixture and the connected product, and complete the structural and dimensional verification of the vibration test fixture.

[0007] Furthermore, the initial design of the completed vibration test fixture includes: Determine the boundaries of the launch vehicle sections and the installation method for vibration testing; The basic shape of the vibration test fixture is determined based on the dimensions of the launch vehicle section and the electromagnetic vibration table. Determine the geometric dimensions of the vibration test fixture.

[0008] Furthermore, the basic shape of the vibration test fixture includes equal diameter type, flower pot type, and inverted flower pot type.

[0009] Furthermore, determining the geometric shape of the vibration test fixture includes: The inner and outer diameters of the upper and lower flanges are determined based on the mechanical interfaces of the launch vehicle section and the electromagnetic vibration table. The height of the vibration test fixture is determined based on the geometry of the electromagnetic vibration table. Determine the thickness of the rotating wall, as well as the number, distribution, and thickness of the reinforcing ribs.

[0010] Furthermore, finite element simulation calculations are used to optimize the dimensional parameters of the vibration test fixture, including: A finite element simulation model of the vibration test fixture was established, material parameters were assigned, and the initial sample fixture was simulated and predicted. Based on the static simulation results and modal simulation results, the inner and outer diameters and heights of the upper and lower flange surfaces, the rotational wall thickness, the number of reinforcing ribs, the distribution of reinforcing ribs, the thickness of reinforcing ribs, and the number and distribution of weight reduction holes were adjusted to obtain a sample fixture that meets the usage requirements.

[0011] Furthermore, the joint simulation of the vibration testing fixture and the connected product is completed to verify the structure and dimensions of the vibration testing fixture, including: The assembly simulation and harmonious response simulation of the sample tooling and the product were carried out to verify whether there was interference between the tooling and the electromagnetic vibration table and the launch vehicle section, and whether the connection holes were operable. The strength of the sample tooling and the product is checked. The dynamic response of the product is equivalent to a static load, and a safety margin is set to complete the strength check. Based on the results of harmonic response simulation analysis, verify whether the strength and stiffness of the tooling meet the requirements, identify the stress concentration points of the tooling, and determine whether reinforcement is needed based on the safety factor.

[0012] The beneficial effects of this invention are as follows: This invention provides an optimized design method for a large, lightweight, high-strength, and high-rigidity vibration testing fixture, applicable to large, lightweight vibration testing fixtures for medium and heavy-lift launch vehicle modules. Compared to traditional large vibration testing fixture designs, the large, lightweight vibration testing fixture proposed in this invention is made of magnesium alloy, which can reduce weight by approximately 40%, saving thrust in the vibration testing system and ensuring the high-volume testing and evaluation requirements of medium and heavy-lift launch vehicle modules.

[0013] This invention provides selection of geometric parameters for vibration fixtures applicable to medium, large and heavy launch vehicles. It summarizes the stiffness, strength and dimensional technical parameters of large, lightweight, high-strength and high-rigidity vibration fixtures that have been verified by experiments. These parameters can be used as a reference for the design technical requirements of other types of vibration test fixtures, enabling the efficient design of high-performance vibration fixtures.

[0014] The high-strength and high-rigidity tooling optimization design method provided by this invention covers multiple disciplines such as assembly, strength, and modal harmonious response analysis. It comprehensively and multi-dimensionally designs, optimizes, and verifies large-scale vibration tooling. Based on engineering experience and actual application effects, it provides clear, feasible, and effective simulation schemes and verification methods to help designers optimize tooling in a targeted manner based on simulation results. At the same time, it gives the key points that need to be verified in the design, and finally obtains vibration tooling with better performance. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of an optimization design method for a large, lightweight, high-strength, and high-rigidity vibration testing fixture according to an embodiment of the present invention. Figure 2 , Figure 3 and Figure 4 This is a schematic diagram showing the structure and dimensions of the test fixture according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the initial prototype model of the vibration testing fixture according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the finite element model of the initial prototype of the vibration test fixture according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the modal simulation analysis results of the prototype model of the vibration test fixture according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the strength simulation analysis results of the initial prototype model of the vibration test fixture according to an embodiment of the present invention; Figure 9 This is a schematic diagram of a vibration testing fixture structure that meets the usage requirements according to an embodiment of the present invention; Figure 10 and Figure 11 This is a schematic diagram of the harmonic response verification analysis results of a vibration testing fixture that meets the usage requirements according to an embodiment of the present invention and the connected product. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0017] Example 1 This invention provides an optimized design method for a large, lightweight, high-strength, and high-stiffness vibration testing fixture, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps: Complete the initial design of the vibration test fixture; The dimensional parameters of the vibration test fixture were optimized using finite element simulation. Complete the joint simulation of the vibration test fixture and the connected product, and complete the structural and dimensional verification of the vibration test fixture.

[0018] The initial design of the completed vibration test fixture includes: Determine the boundaries of the launch vehicle sections and the installation method for vibration testing; The basic shape of the vibration test fixture is determined based on the dimensions of the launch vehicle section and the electromagnetic vibration table. Determine the geometric dimensions of the vibration test fixture.

[0019] The basic shapes of the vibration test fixture include equal diameter type, flower pot type, and inverted flower pot type.

[0020] The determination of the geometric shape of the vibration test fixture includes: The inner and outer diameters of the upper and lower flanges are determined based on the mechanical interfaces of the launch vehicle section and the electromagnetic vibration table. The height of the vibration test fixture is determined based on the geometry of the electromagnetic vibration table. Determine the thickness of the rotating wall, as well as the number, distribution, and thickness of the reinforcing ribs.

[0021] Finite element method (FEM) simulation was used to optimize the dimensional parameters of the vibration test fixture, including: A finite element simulation model of the vibration test fixture was established, material parameters were assigned, and the initial sample fixture was simulated and predicted. Based on the static simulation results and modal simulation results, the inner and outer diameters and heights of the upper and lower flange surfaces, the rotational wall thickness, the number of reinforcing ribs, the distribution of reinforcing ribs, the thickness of reinforcing ribs, and the number and distribution of weight reduction holes were adjusted to obtain a sample fixture that meets the usage requirements.

[0022] The joint simulation of the vibration test fixture and the connected product is completed, and the structural and dimensional verification of the vibration test fixture is performed, including: The assembly simulation and harmonious response simulation of the sample tooling and the product were carried out to verify whether there was interference between the tooling and the electromagnetic vibration table and the launch vehicle section, and whether the connection holes were operable. The strength of the sample tooling and the product is checked. The dynamic response of the product is equivalent to a static load, and a safety margin is set to complete the strength check. Based on the results of harmonic response simulation analysis, verify whether the strength and stiffness of the tooling meet the requirements, identify the stress concentration points of the tooling, and determine whether reinforcement is needed based on the safety factor.

[0023] Example 2 1. Complete the initial design of the vibration test fixture. The basic shape of the vibration test fixture is determined based on the mechanical interfaces of the test requirements (test subject: launch vehicle segment) and the test equipment (electromagnetic vibration table), such as equal diameter (upper and lower flange diameters are similar), flowerpot shape (upper flange diameter is larger than lower flange diameter), and inverted flowerpot shape (upper flange diameter is smaller than lower flange diameter). Considering the dimensions of most domestic vibration test equipment and medium-to-large heavy-duty rocket segments, the flowerpot-shaped vibration test fixture is generally chosen.

[0024] The lower flange of the flowerpot fixture should match the electromagnetic vibration table and should not exceed the minimum docking dimensions of the electromagnetic vibration table (including the mechanical interface dimensions of the vertical expansion table and the transverse slide table); the upper flange of the flowerpot fixture should match the launch vehicle section and be able to enclose the docking mechanical interface of the section; the height, stiffener distribution, and shape of the flowerpot fixture should not interfere with the electromagnetic vibration table. The thickness of the rotating arm is generally 30mm~60mm, the stiffener distribution is generally circumferentially even, and the number of stiffeners is generally selected as 8, 12, 16, 20, or 24. While meeting the above requirements, the flowerpot fixture should be as low as possible to facilitate the enhancement of rigidity and the reduction of mass.

[0025] The flowerpot fixture includes an upper flange, lower flange, rotating wall, reinforcing ribs, weight-reducing holes, and fastener interfaces, such as... Figure 2-4As shown, its dimensional parameters include: H1 is the tooling height, D1 is the outer diameter of the upper flange, D2 is the inner diameter of the upper flange, T1 is the thickness of the upper flange, D3 is the outer diameter of the lower flange, D4 ​​is the inner diameter of the lower flange, T2 is the thickness of the lower flange, T3 is the thickness of the inner reinforcing rib, L is the inner extension of the upper surface of the inner reinforcing rib, T4 is the thickness of the outer long reinforcing rib, T5 is the thickness of the outer short reinforcing rib, H2 is the height of the outer short reinforcing rib, P1 is the product mechanical interface, P2 is the vibration system mechanical interface, and M is the diameter of the weight reduction hole.

[0026] 2. Finite element simulation was used to optimize the dimensional parameters of the vibration test fixture. According to the initial model of the vibration test fixture (such as...) Figure 5 Establish a finite element model (as shown) Figure 6 As shown in the figure, simulations are performed to predict the model's performance, and the model is then optimized based on the simulation results. The preferred mesh type is a hexahedral structured mesh, followed by a tetrahedral unstructured mesh, and finally, a shell mesh can be simplified for simulation optimization.

[0027] Assigning material parameters: Material properties should first be determined by consulting the material handbook based on the magnesium alloy grade and heat treatment process. Secondly, the following general magnesium alloy material parameters can be referenced: Elastic modulus E = 45 GPa, Poisson's ratio µ = 0.35, density ρ = 1800 kg / m³. 3 Yield strength 200 MPa.

[0028] Conduct modal simulation analysis (see schematic diagram of results) Figure 7 As shown in the figure, in order to avoid the fact that the first-order vibration test frequency range of the flower pot fixture for the launch vehicle section is generally below 100Hz, the first-order frequency of the magnesium-aluminum alloy flower pot fixture should be higher than 100Hz.

[0029] Conduct strength simulation analysis (see schematic diagram of results) Figure 8 As shown in the figure, the static strength simulation level under the assembly of the launch vehicle module should be less than 1 / 5 of the material's ultimate strength, and the static strength simulation level should be verified according to the static strength criterion.

[0030] Based on the static and modal simulation results, the design of the upper and lower flange surfaces, height, rotational wall thickness, number of reinforcing ribs, distribution of reinforcing ribs, thickness of reinforcing ribs, and weight reduction holes were optimized using sensitivity analysis to obtain a sample fixture that meets the usage requirements (e.g., Figure 9 (As shown).

[0031] 3. Complete the joint simulation of the vibration test fixture and the connected product, and complete the structural and dimensional verification of the vibration test fixture. The obtained sample fixture is assembled with the product to be tested, and simulation is performed according to the test conditions. The vibration test fixture is then checked.

[0032] Due to the complexity of the tooling structure and its connection to both the module and the vibration testing system, assembly simulation verification is recommended. This verification should check for interference between the tooling and the electromagnetic vibration table and the launch vehicle module, as well as the operability of the connection holes. The tooling should have pre-drilled connection holes for fixing to the electromagnetic vibration table and for connecting to the launch vehicle module. The holes for connecting to the electromagnetic vibration table should be countersunk through holes, and the number should meet the strength requirements for testing. The connection holes for the launch vehicle module can be designed as through holes or threaded holes; through holes are recommended for easier connection and installation during testing. If threaded holes are used, steel sleeves should be inserted to enhance the strength of the connection.

[0033] Assemble the sample tooling with the product and perform strength verification. Based on engineering experience, the dynamic response amplification factor of the product is generally 3 to 10 times. Therefore, it is necessary to select a certain amplification factor to treat the dynamic response load as an inertial force load or a concentrated force load, which acts together with other loads on the tooling and product assembly model. Perform strength verification according to a safety margin of 1.2 to 1.5 times to ensure that the stress level of the tooling is less than 1 / 5 of the material's ultimate strength.

[0034] Since the vibration tests of the medium-to-heavy-lift launch vehicle sections mainly involve low-frequency sinusoidal sweep vibrations, with a small portion requiring random vibrations, it is advisable to conduct harmonic response verification analysis of the sections and test fixtures (results are as follows). Figure 10 , 11 As shown in the figure, the strength and stiffness of the tooling are verified based on the harmonic response simulation analysis results. The stress concentration points of the tooling are identified and it is determined whether reinforcement is needed based on the safety factor.

[0035] Due to the complexity of the tooling structure and its connection to both the module and the vibration testing system, assembly simulation verification is recommended. This verification should check for interference between the tooling and the electromagnetic vibration table and the launch vehicle module, as well as the operability of the connection holes. The tooling should have pre-drilled connection holes for fixing to the electromagnetic vibration table and for connecting to the launch vehicle module. The holes for connecting to the electromagnetic vibration table should be countersunk through holes, and the number should meet the strength requirements for testing. The connection holes for the launch vehicle module can be designed as through holes or threaded holes; through holes are recommended for easier connection and installation during testing. If threaded holes are used, steel sleeves should be inserted to enhance the strength of the connection.

[0036] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for optimizing the design of a large, lightweight, high-strength, and high-stiffness vibration testing fixture, characterized in that, The steps include the following: Complete the initial design of the vibration test fixture; The dimensional parameters of the vibration test fixture were optimized using finite element simulation. Complete the joint simulation of the vibration test fixture and the connected product, and complete the structural and dimensional verification of the vibration test fixture.

2. The method for optimizing the design of a large, lightweight, high-strength, and high-stiffness vibration testing fixture according to claim 1, characterized in that, The initial design of the completed vibration test fixture includes: Determine the boundaries of the launch vehicle sections and the installation method for vibration testing; The basic shape of the vibration test fixture is determined based on the dimensions of the launch vehicle section and the electromagnetic vibration table. Determine the geometric dimensions of the vibration test fixture.

3. The method for optimizing the design of a large, lightweight, high-strength, and high-stiffness vibration testing fixture according to claim 1, characterized in that, The basic shapes of the vibration test fixture include equal diameter type, flower pot type, and inverted flower pot type.

4. The method for optimizing the design of a large, lightweight, high-strength, and high-stiffness vibration testing fixture according to claim 2, characterized in that, The determination of the geometric shape of the vibration test fixture includes: The inner and outer diameters of the upper and lower flanges are determined based on the mechanical interfaces of the launch vehicle section and the electromagnetic vibration table. The height of the vibration test fixture is determined based on the geometry of the electromagnetic vibration table. Determine the thickness of the rotating wall, as well as the number, distribution, and thickness of the reinforcing ribs.

5. The method for optimizing the design of a large, lightweight, high-strength, and high-stiffness vibration testing fixture according to claim 4, characterized in that, Finite element method (FEM) simulation was used to optimize the dimensional parameters of the vibration test fixture, including: A finite element simulation model of the vibration test fixture was established, material parameters were assigned, and the initial sample fixture was simulated and predicted. Based on the static simulation results and modal simulation results, the inner and outer diameters and heights of the upper and lower flange surfaces, the rotational wall thickness, the number of reinforcing ribs, the distribution of reinforcing ribs, the thickness of reinforcing ribs, and the number and distribution of weight reduction holes were adjusted to obtain a sample fixture that meets the usage requirements.

6. The method for optimizing the design of a large, lightweight, high-strength, and high-stiffness vibration testing fixture according to claim 5, characterized in that, The joint simulation of the vibration test fixture and the connected product is completed, and the structural and dimensional verification of the vibration test fixture is performed, including: The assembly simulation and harmonious response simulation of the sample tooling and the product were carried out to verify whether there was interference between the tooling and the electromagnetic vibration table and the launch vehicle section, and whether the connection holes were operable. The strength of the sample tooling and the product is checked. The dynamic response of the product is equivalent to a static load, and a safety margin is set to complete the strength check. Based on the results of harmonic response simulation analysis, verify whether the strength and stiffness of the tooling meet the requirements, identify the stress concentration points of the tooling, and determine whether reinforcement is needed based on the safety factor.

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