A four-field coupling test structure and its design method

Abstract

The present invention provides a four-field coupling test structure and its design method. The test structure includes a main structure, a sealing material, and a skin. The main structure includes a frame, reinforcing ribs, and a clamping structure. The frame includes a rectangular bottom plate and rectangular side frames located on the four sides of the bottom plate. The reinforcing ribs are arranged vertically and horizontally between two pairs of parallel sides of the rectangular side frames. The clamping structure is fixed to the bottom of the frame. Pressure holes and sealing grooves are provided on the rectangular side frames, and the sealing grooves form a closed structure along the four sides of the rectangular side frames. The sealing material fills the sealing grooves. The skin covers the exposed surface of the frame, and the skin and the sealing material are fixed to the frame through fixing components. This test structure uses the method of internal pressure loading to apply static loads, avoiding the mutual influence between static loads and the loading of vibration and noise loads, and solving the problem of accurate loading of each load in the four-field coupling test. By optimizing the design of the test structure parameters, obvious strain, displacement, and acceleration responses are ensured.

Description

Technical Field

[0001] The present invention belongs to the field of aerospace technology, and particularly relates to a four-field coupling test structure applicable to static + vibration + noise + heat test research and a design method thereof. Background Technique

[0002] The flight environment of high-speed aircraft is complex, and it bears a harsh environment of multi-field coupling such as static force, vibration, heat, and noise. The reliability of the structure is often verified by means of test verification. The single-load-field structural strength test and the two-field combined structural strength tests such as thermal-mechanical and thermal-vibration in the prior art increasingly show defects such as "under-test". Due to the lack of sufficient design, loading, and measurement means, and the lack of engineering development data and experience accumulation, the four-field combined test method is not mature and cannot meet the actual engineering requirements. Conventional test pieces use external contact methods such as actuators to load static loads. When combined with vibration loads or noise loads, they affect each other's loading accuracy, making it difficult for conventional test pieces to accurately load four-field loads. Summary of the Invention

[0003] The purpose of the present invention is to provide a four-field coupling test structure and a design method thereof. The test structure uses internal pressurization to load static loads, avoiding the mutual influence between static loads and vibration and noise loads, and solving the problem of accurate loading of each load in the four-field coupling test.

[0004] The technical solution adopted by the present invention to achieve the above purpose is as follows:

[0005] On the one hand, the present invention provides a four-field coupling test structure, including a main structure, a sealing material, and a skin; the main structure includes a frame, reinforcing ribs, and a clamping structure. The frame includes a rectangular bottom plate and rectangular side frames located on the four sides of the bottom plate. The reinforcing ribs are arranged vertically and horizontally between two pairs of parallel sides of the rectangular side frames. The clamping structure is fixed to the bottom of the frame. Pressurization holes and sealing grooves are opened on the rectangular side frames. The sealing grooves form a closed structure along the four sides of the rectangular side frames. The sealing material fills the sealing grooves. The skin covers the exposed surface of the frame, and the skin and the sealing material are fixed to the frame through fixing components.

[0006] Further, the reinforcing ribs are symmetric structures along the length direction, or the reinforcing ribs adopt a variable-width structure, or the reinforcing ribs simultaneously adopt a symmetric structure along the length direction and a variable-width structure.

[0007] Further, the clamping structure has the same installation form as the rudder surface; the pressurization holes are located at the bottom edge of the rectangular side frames and are symmetrically arranged on both sides of the clamping structure; after the four-field coupling test structure is stamped through the pressurization holes, the pressurization holes are sealed with sealant.

[0008] Further, the fixing member is a screw. Screw mounting holes are uniformly formed on the surface of the rectangular frame parallel to the bottom plate. After the skin is fixed with the screws, sealant is applied for sealing.

[0009] Further, the thickness of the skin is the same as that of the rectangular bottom plate in the frame. Reinforcing ribs are provided on the opposite inner surfaces of the skin and the rectangular bottom plate.

[0010] On the other hand, the present invention also provides a design method for a four-field coupling test structure, including the following steps

[0011] S1. Design the initial structural parameters of the four-field coupling test structure according to the structural parameters of the rudder surface.

[0012] S2. In the finite element analysis software, construct the initial model of the four-field coupling test structure according to the initial structural parameters. Adjust a certain structural parameter of the four-field coupling test structure. Under the action of a single load, respectively obtain the strength-strain and strength-displacement correlation relationships of the four-field coupling test structure under the condition of changing a single structural parameter, and calculate the weight ranking of each structural parameter affecting the strain and displacement.

[0013] S3. According to the structural performance of the rudder surface, select the frame and skin parameters based on the weight ranking results, determine the structural parameters of the four-field coupling test structure, conduct finite element analysis, and determine whether the static strength and dynamic strength meet the requirements; conduct the stability calculation of the four-field coupling test structure. If the skin shows instability, add skin reinforcing ribs on the inner sides of the skin and the bottom plate, and optimize the parameters of the skin reinforcing ribs.

[0014] Further, the specific steps of step S1 include the following steps

[0015] S1.1. At the root of the rudder surface and near the rudder shaft, select local areas with large environmental loads and obvious deformation responses. According to the height, width, and thickness of the local areas, preliminarily determine the height, width, and thickness of the frame.

[0016] S1.2. Preset the frame width according to the requirements for opening the sealing groove, screw mounting holes, and pressure charging holes.

[0017] S1.3. Preset the thickness, width of the reinforcing ribs between the frames, and the spacing between the reinforcing ribs; set the parameters of the skin reinforcing ribs to 0.

[0018] Further, the local areas are determined by the test nephogram of the rudder surface at the positions where the strain and stress change significantly. The local areas are symmetric structures.

[0019] Further, the specific steps of step S2 include the following steps

[0020] Construct the initial model of the test structure in the finite element analysis software;

[0021] Adjust one of the factors of the frame border width, frame height, frame thickness, stiffener width, stiffener spacing, and stiffener thickness, and separately obtain the strength-strain and strength-displacement correlation relationships of the four-field coupling test structure under the single action of static load, vibration load, thermal load, or noise load under the condition of the change of a single factor.

[0022] Establish an orthogonal analysis table, and through range analysis, obtain the weight ranking of each structural parameter affecting the strain and displacement of the four-field coupling test structure.

[0023] Further, the method for optimizing the skin stiffener parameters in step S3 is

[0024] Through finite element analysis, preliminarily set the parameters of the skin stiffener, including the skin stiffener thickness, width, and spacing.

[0025] Adjust the skin stiffener parameters, and check and verify that the four-field coupling test structure simultaneously meets the requirements of static strength, dynamic strength, and stability.

[0026] The beneficial effects of the present invention compared with the prior art:

[0027] The four-field coupling test structure proposed by the present invention is used to simulate the local structure of the aircraft rudder surface, and includes a frame with a sealing groove and a pressure hole, a stiffener with a variable width, a clamping structure simulating the rudder surface installation form, and a skin with a sealed assembly. This test structure realizes the static load loading through internal pressurization, avoiding the influence of the loading accuracy of static load, vibration load, and noise load; by optimizing the design of the test structure parameters, it ensures obvious strain, displacement, and acceleration responses. This four-field coupling test structure can truly simulate the rudder surface performance and effectively verify the aircraft rudder surface structure. Description of the Drawings

[0028] The included drawings are used to provide a further understanding of the embodiments of the present invention, which form a part of the specification, are used to illustrate the embodiments of the present invention, and are used to explain the principles of the present invention together with the text description. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0029] Figure 1 Schematic diagram of the four-field coupling test structure provided for the specific embodiment of the present invention;

[0030] Figure 2 For Figure 1 Cross-sectional view of the structure shown in the A-A direction;

[0031] Figure 3 For Figure 1 Cross-sectional view of the structure shown in the B-B direction;

[0032] Figure 4 is Figure 1 the bottom view of the shown structure.

[0033] Among them, the above-mentioned drawings include the following reference numerals:

[0034] 1. Frame; 2. Reinforcing rib; 3. Pressurizing hole; 4. Clamping structure; 5. Mounting hole; 6. Skin. Specific embodiments

[0035] The specific embodiments of the present invention will be described in detail below. In the following description, for the purpose of explanation rather than limitation, specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details.

[0036] It should be noted here that in order to avoid obscuring the present invention with unnecessary details, only the device structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0037] For carrying out the four-field coupling test research, the present invention proposes a four-field coupling test structure and its design method, which avoids the mutual influence between the static load and the vibration and noise loadings.

[0038] A four-field coupling test structure provided by the present invention includes a main structure, a skin, and a sealing felt. Among them, the main structure includes a frame 1, a reinforcing rib 2, a pressurizing hole 3, a clamping structure 4, and a mounting hole 5.

[0039] As Figure 1 shown, the frame 1 includes a rectangular bottom plate and rectangular frames on the four sides of the bottom plate, and the frame 1 is integrally formed. Among them, the frame parameters include width and thickness. The frame width is the distance between the inner and outer edges of each side, and the widths of the four sides of the frame are the same. The frame thickness is the length in the direction perpendicular to the bottom plate.

[0040] The clamping structure 4 is located at the bottom of the frame 1, and the clamping structure 4 has the same installation form as the rudder surface. In this embodiment, the clamping structure 4 is connected to the vibration table by 4 connecting screws.

[0041] As Figure 2 、 3As shown, the stiffeners 2 are arranged vertically and horizontally between two pairs of parallel sides of the rectangular frame, forming a grid-like structure. The thickness of the stiffener is defined as the length in the direction of the frame thickness (i.e., the length perpendicular to the bottom plate), and the width of the stiffener is the length perpendicular to the length and thickness directions. Preferably, the stiffener 2 adopts a variable-width design. In subsequent optimization designs, according to the changing requirements of strain and displacement, the variable-width form of the stiffener is adjusted. For example, the two ends of the stiffener 2 can be narrow and the middle can be wide, or the two ends can be wide and the middle can be narrow, or the width can decrease from one end to the other. At the position where the width of the stiffener is large, the strain is large and the displacement is small. This design enables the test structure to better respond to strain, displacement, and acceleration. Additionally, preferably, for the convenience of test measurement and verification, the stiffeners are symmetrically designed, and each stiffener 2 is a symmetric structure along its length direction.

[0042] As Figure 1 , 4 shown, pressure holes 3, sealing grooves, and screw mounting holes 5 are provided on the frame. The pressure holes 3 are located at the bottom edge of the frame and are symmetrically arranged on both sides of the clamping structure 4. The sealing grooves are opened along the four sides of the frame, enclosing a closed structure, and the screw mounting holes are evenly opened along the four sides of the frame.

[0043] The sealing felt is filled in the sealing groove, the skin 6 covers the frame 1, and the connecting screws press the sealing felt, the skin, and the frame tightly. The pressure holes, the sealing felt, and the connecting screws are used in cooperation when loading static loads. The pressure holes are used to load static loads, and the sealing felt is used to seal the gap between the skin and the frame to prevent pressure load leakage.

[0044] The thickness of the skin 6 is the same as the thickness of the bottom plate in the frame (the bottom plate simulates the skin on one side of the rudder surface). If the test structure shows instability, skin stiffeners also need to be provided on the inner surfaces of the skin 6 and the bottom plate opposite to each other to increase the stability of the test structure.

[0045] Installation process of the test structure: First, install the sealing felt in the sealing groove of the rectangular frame of the frame, press the skin on the frame; then install the screws to press the skin tightly, apply sealant on the screws to enhance the sealing effect. Finally, install the test structure on the vibration table, connect the pressure equipment through the pressure holes. After stamping, apply sealant on the pressure holes to ensure the stability of the internal pressure of the structure.

[0046] This test structure uses the method of internal pressurization to load static loads, avoiding the influence on the loading accuracy of static loads, vibration, and noise loads caused by using conventional contact loading such as actuators under vibration loads, and achieving the decoupling of the three.

[0047] To ensure that the above four-field coupling test structure can effectively complete the four-field coupling test, the present invention also provides a design method for the four-field coupling test structure, which specifically includes the following steps:

[0048] 1. Design the initial structural parameters of the test structure according to the control surface structure parameters.

[0049] The structural parameters to be designed for the four-field coupling test structure include: the height, width, and thickness of the frame, the border width, the border thickness is the same as the frame thickness, the thickness and width of the stiffeners, the spacing between the stiffeners, and the thickness, width, and spacing of the skin stiffeners.

[0050] 1.1. Select local areas with large environmental loads and obvious deformation responses at the root of the control surface and near the control surface shaft. The local areas with obvious changes in strain and stress can be determined through the test cloud map of the control surface, and the local areas are preferably symmetric structures. According to the height, width, and thickness of the local areas, preliminarily determine the height, width, and thickness of the frame.

[0051] 1.2. Preset the border width according to the requirements for opening the sealing groove, screw mounting holes, and pressure charging holes, so as to meet the installation of screws and sealing felts.

[0052] The size of the screw mounting holes needs to meet the strength requirements under four loads. At the same time, the number of screw mounting holes needs to be as dense as possible to ensure the tight fit of the sealing felt and the sealing groove; the pressure charging holes are opened at the bottom of the border to facilitate the connection of the pressure charging equipment and avoid interference with other loading equipment. The diameter of the pressure charging holes is designed according to the size of the connection device of the pressure charging equipment.

[0053] 1.3. Preset the thickness, width, and spacing between the stiffeners between the borders. In the initial parameters, the parameters of the skin stiffeners are 0.

[0054] 2. In the finite element analysis software, construct the initial model of the test structure according to the initial structural parameters, adjust one structural parameter of the test structure, and under the action of a single load, respectively obtain the strength-strain and strength-displacement correlation relationships of the test structure under the condition of changing a single structural parameter, and calculate the weight ranking of each structural parameter affecting strain and displacement.

[0055] Through the finite element analysis software, carry out the sensitivity analysis of the test structure parameters to extract the structural parameters under different responses and obtain the structural design parameters.

[0056] First, construct the initial model of the test structure, adjust a single factor among the border width, frame height, frame thickness, stiffener width, stiffener spacing, and stiffener thickness, and under the action of each of the four loads alone, respectively obtain the strength-strain and strength-displacement correlation relationships of the test structure under the condition of changing a single factor.

[0057] Then, establish an orthogonal analysis table, and through range analysis, obtain the weight ranking of each structural parameter affecting the strain and displacement of the test structure. The establishment of the orthogonal analysis table refers to "Orthogonal Test Method" published by National Defense Industry Press.

[0058] 3. According to the structural performance of the control surface, select the frame, stiffener, and skin parameters from the weight sorting results in Step 2, determine the structural parameters of the four-field coupling test structure, conduct finite element analysis to determine whether the static strength and dynamic strength meet the requirements; conduct stability calculations on the four-field coupling test structure. If skin buckling occurs, add skin stiffeners to the inner sides of the skin and the bottom plate of the four-field coupling test structure, and optimize the parameters of the skin stiffeners.

[0059] In accordance with the requirements of studying the four-field test, the stress, acceleration, and displacement responses caused by the four loads of force, heat, sound, and vibration should change significantly during single-field, two-field, three-field, and four-field tests. Based on this requirement, select the parameters of the frame and skin from Step 2. Conduct finite element analysis according to the final test structure parameters to check whether the static strength and dynamic strength meet the requirements. If they do not meet the requirements, re-select the parameters of the frame, stiffeners, and skin.

[0060] At the same time, conduct stability calculations on the test structure that meets the requirements of static strength and dynamic strength. If skin buckling occurs, skin stiffeners can be added to the inner sides of the skin and the bottom plate. The method for selecting the parameters of the skin stiffeners is as follows:

[0061] 1) Through finite element calculation, preliminarily set the parameters of the skin stiffeners, including the thickness, width, and spacing of the stiffeners, to meet stability.

[0062] 2) Due to the limited internal space of the closed test structure, setting stiffeners on the skin will cause a decrease in the strength of the rest of the test structure. Therefore, it is necessary to re-check the static strength, dynamic strength, and stability of the entire test structure.

[0063] 3) When the entire test structure meets the requirements of strength and stability, determine the final parameters of the skin stiffeners.

[0064] The results such as strength, displacement, and strain required for the above calculations are all obtained through finite element calculation.

[0065] In the test structure provided by the present invention, the design of the structural parameters such as the frame, border, and stiffeners is based on simulating the control surface structural parameters. At the same time, under static, vibration, noise, and thermal environment loads, through strength calculation, it is ensured that during static, vibration, noise, and thermal environment tests, the displacement, strain, and acceleration responses are obvious. If the responses are not obvious, it is necessary to adjust the parameters such as the border width, frame height, frame thickness, stiffener width, stiffener spacing, stiffener thickness, and skin stiffeners until the responses of the test structure meet the requirements and then determine the structural parameters.

[0066] In the four-field coupling test structure designed in this embodiment, the frame, stiffeners, and skin are all made of superalloy materials. The outline dimensions of the test structure are 600mm×450mm×75mm. The width of the frame is 70mm, the thickness of the frame is 30mm, the position of the stiffeners near the clamping structure is 5mm, and the variation range from one end of the frame to the other end is 5mm to 2mm respectively. The diameter of the pressure hole is 10mm, the mounting hole is an M10 threaded hole, and the diameter of the connecting screw is 12mm. The width of the sealing groove is 3mm and the depth is 4mm. The thickness of the skin is 1.5mm.

[0067] When conducting the four-field coupling test on the test structure designed by the present invention, the test structure is installed on the vibration table, and the load of the vibration table is transmitted to the structure through the clamping structure. Static load is applied by pressurizing the inside of the test structure. The test structure is placed in the traveling-wave tube, and noise load is applied. The traveling-wave tube is above the vibration table, and the vibration table applies vibration load. A quartz lamp is used to heat the traveling-wave tube and the test structure together to apply thermal load. Strain, displacement, and acceleration test equipment are set on the test structure, and the progress of the test is monitored through responses such as strain, displacement, and acceleration.

[0068] Features described and / or illustrated for one embodiment above can be used in the same or similar manner in one or more other embodiments, and / or combined with features in other embodiments or used to replace features in other embodiments.

[0069] It should be emphasized that the term "comprising / including" when used herein refers to the presence of features, whole things, steps, or components, but does not exclude the presence or addition of one or more other features, whole things, steps, components, or combinations thereof.

[0070] Many features and advantages of these embodiments are clear from this detailed description, and thus the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. In addition, since many modifications and changes are readily conceivable by those skilled in the art, the embodiments of the present invention are not to be limited to the exact structures and operations illustrated and described, but may cover all suitable modifications and equivalents falling within their scope.

[0071] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0072] The parts not detailed in the present invention are well-known technologies to those skilled in the art.

Claims

1. A design method for a four-field coupling test structure, characterized in that The four-field coupling test structure includes a main structure, a sealing material, and a skin; the main structure includes a frame, stiffeners, and a clamping structure. The frame includes a rectangular bottom plate and rectangular side frames located on the four sides of the bottom plate. The stiffeners are arranged vertically and horizontally between two pairs of parallel sides of the rectangular side frames. The clamping structure is fixed to the bottom of the frame. Pressure holes and sealing grooves are opened on the rectangular side frames, and the sealing grooves form a closed structure along the four sides of the rectangular side frames; the sealing material is filled in the sealing grooves; the skin covers the exposed surface of the frame, and the skin and the sealing material are fixed to the frame through fixing components; the design method includes the following steps, S1. Design the initial structure parameters of the four-field coupling test structure according to the structural parameters of the rudder surface; S2. In the finite element analysis software, construct the initial model of the four-field coupling test structure according to the initial structure parameters. Adjust a certain structure parameter of the four-field coupling test structure. Under the action of a single load, respectively obtain the strength-strain and strength-displacement correlation relationships of the four-field coupling test structure under the condition of changing a single structure parameter, and calculate the weight ranking of each structure parameter affecting strain and displacement; S3. According to the structural performance of the rudder surface, select the parameters of the frame, stiffeners, and skin based on the weight ranking results, determine the structural parameters of the four-field coupling test structure, conduct finite element analysis, and determine whether the static strength and dynamic strength meet the requirements; conduct the stability calculation of the four-field coupling test structure. If the skin shows instability, add skin stiffeners on the inner side of the skin and the bottom plate, and optimize the parameters of the skin stiffeners.

2. The design method of the four-field coupling test structure according to claim 1, wherein The specific steps of step S1 include the following steps, S1.

1. Select local areas with large environmental loads and obvious deformation responses at the root of the rudder surface and near the rudder shaft. According to the height, width, and thickness of the local areas, preliminarily determine the height, width, and thickness of the frame; S1.

2. Preset the width of the side frame according to the opening requirements of the sealing groove, screw mounting holes, and pressure holes; S1.

3. Preset the thickness, width of the stiffeners between the side frames, and the spacing between the stiffeners; set the parameters of the skin stiffeners to 0.

3. The design method of the four-field coupling test structure according to claim 2, characterized in that The local areas are determined by the test cloud map of the rudder surface at the positions where the strain and stress change significantly, and the local areas are symmetric structures.

4. The design method of the four-field coupling test structure according to claim 2, characterized in that, The specific steps of step S2 include the following steps, Construct the initial model of the test structure in the finite element analysis software; Adjust one of the factors of the side frame width, frame height, frame thickness, stiffener width, stiffener spacing, and stiffener thickness. Under the separate action of static load, vibration load, thermal load, or noise load, respectively obtain the strength-strain and strength-displacement correlation relationships of the four-field coupling test structure under the condition of changing a single factor; Establish an orthogonal analysis table, and through range analysis, obtain the weight ranking of each structure parameter affecting the strain and displacement of the four-field coupling test structure.

5. The design method of the four-field coupling test structure according to claim 4, characterized in that, The method for optimizing the parameters of the skin stiffeners in step S3 is, Through finite element analysis, preliminarily set the parameters of the skin stiffeners, including the thickness, width, and spacing of the skin stiffeners; Adjust the parameters of the skin stiffeners, and check that the four-field coupling test structure meets the requirements of static strength, dynamic strength, and stability at the same time.

6. The design method of the four-field coupling test structure according to claim 1, characterized in that The rib is symmetric along the length direction, or the rib has a variable width structure, or the rib simultaneously has a symmetric structure along the length direction and a variable width structure.

7. The design method of the four-field coupling test structure according to claim 1, characterized in that The clamping structure has the same installation form as the rudder surface; the pressure charging holes are located at the bottom edge of the rectangular frame and are symmetrically arranged on both sides of the clamping structure; after the four-field coupling test structure is stamped through the pressure charging holes, the pressure charging holes are sealed with sealant.

8. The design method of the four-field coupling test structure according to claim 1, characterized in that The fixing component is a screw. The rectangular frame is evenly provided with screw mounting holes on the surface parallel to the bottom plate. After the skin is fixed with the screw, sealant is applied for sealing.

9. The design method of the four-field coupling test structure according to claim 1, characterized in that The thickness of the skin is the same as that of the rectangular bottom plate in the frame. Skin ribs are arranged on the inner surfaces of the skin and the rectangular bottom plate facing each other.

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