Vibration testing device and method for rocket engine

Abstract

The invention discloses a vibration testing device and method for a rocket engine, and solves the technical problems that an existing vibration block is poor in adaptability due to the adoption of a mechanical fixing mode, and is easy to partially peel off or fall off due to pasting and fixing, so that the testing data is inaccurate, and the vibration testing device comprises a pasting plate, a stud, a gasket and a vibration testing square block, the stud is located at the axis of the upper surface of the pasting plate, and the bottom of the stud is fixedly connected with the pasting plate. Threaded holes are formed in the axes of the six faces of the vibration testing square block respectively, one face of the vibration testing square block is connected with the stud through the threaded hole, and the remaining threaded holes are used for installing a testing sensor. The gasket is located between the pasting plate and the vibration measurement square block and is in threaded connection with the stud. The shape of the pasting plate is matched with the shape of a position to be pasted; the pasting plate projects towards a front projection plane, tangent lines are made at the two ends of the bending and extending direction of the pasting plate, the included angle theta of the extension lines of the two tangent lines is defined to be larger than or equal to 10 degrees and smaller than or equal to 180 degrees.

Description

Technical Field

[0001] This invention relates to an engine vibration testing device, and more specifically to a vibration testing device and method for a rocket engine. Background Technology

[0002] As the "heart" of a space launch mission, the rocket engine operates in an extremely harsh environment, needing to withstand multiple loads including high temperature, high pressure, high-speed airflow, and severe vibration. If the vibration exceeds the design threshold, it may lead to fatigue cracking of the engine structure, pipeline rupture, sensor failure, or even cause the entire engine to explode. Therefore, vibration testing is an indispensable core step in the development, verification, and delivery of rocket engines, aiming to expose design defects in advance, verify structural reliability, and ensure the safety of flight missions.

[0003] Dynamic characteristic analysis of the rigid structure of an engine relies on high-precision vibration data, and the reliability of the measurement point fixing method is fundamental to achieving this goal. For complex surfaces of rocket engine equipment, or special operating conditions such as high temperature and high pressure, traditional methods require direct welding or threaded fixing (mechanical fixing) of the vibration measuring block to the engine equipment surface. While this fixing method is relatively robust, it has significant limitations. Due to structural limitations or technological risks of the rocket engine, or because of low strength of the connection surface (such as thin-walled structures, high-temperature areas, or already in service components), traditional welding or threaded connections can lead to the connection surface and the vibration measuring block vibrating together, still resulting in inaccurate data. At this point, adhesive fixing has emerged as a supplement to mechanical fixing, offering the advantages of being non-invasive and reusable. However, due to the small size of the vibration measuring block (generally on the millimeter scale), the adhesive layer is susceptible to cyclic vibration, temperature changes, and media corrosion, easily leading to localized or complete detachment of the vibration measuring block, especially at the rounded corner bonding surfaces, causing signal transmission interruption or noise interference. This failure mode not only disrupts the continuity of monitoring data but may also introduce phase deviations due to secondary bonding, leading to systematic errors in modal analysis results. Tests on a rocket engine turbine disk showed that the nonlinear response caused by partial peeling of the vibration measurement block resulted in a 0.4-0.6 decrease in the modal confidence factor (MAC), severely impacting the accuracy of parameter identification. Some research institutions have begun exploring non-contact solutions such as magnetic adsorption fixation and laser vibration measurement, but these face bottlenecks such as high cost, low accuracy, and environmental interference, and a better solution has yet to be developed. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problem that existing vibration measurement blocks using mechanical fixing methods have poor adaptability and are prone to partial peeling or falling off when glued, resulting in inaccurate test data. The invention provides a vibration testing device and method for rocket engines.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A vibration testing device for rocket engines, characterized in that it includes an adhesive plate, studs, washers, and a vibration measuring block;

[0007] The stud is located at the center of the upper surface of the adhesive plate, and its bottom is fixedly connected to the adhesive plate;

[0008] The vibration measuring block has threaded holes at the center of each of its six faces. One face of the vibration measuring block is connected to a stud through the threaded hole, and the remaining threaded holes are used to install test sensors.

[0009] The gasket is located between the adhesive plate and the vibration measuring block, and is threadedly connected to the stud.

[0010] The shape of the adhesive board is adapted to the shape of the location to be pasted;

[0011] The adhesive board is projected onto the orthographic projection plane, and tangents are drawn at both ends of the bending extension direction of the adhesive board. Define the angle between the extensions of the two tangents as θ, then 10° ≤ θ ≤ 180°.

[0012] Furthermore, the lower surface of the adhesive plate has a microtexture.

[0013] Furthermore, the threads of the threaded holes on the two opposite faces of the vibration measuring block have opposite directions;

[0014] The test sensor has a connecting screw, which is connected to the vibration measuring block through a threaded hole. After the test sensor is tightened, the connecting screw abuts against the stud.

[0015] This invention also provides a vibration testing method for rocket engines, characterized by comprising the following steps:

[0016] Step 1: Determine the thrust direction of the rocket engine and, based on the vibration test requirements, determine the location where the vibration measurement block will be pasted.

[0017] Step 2: Determine the shape and size of the adhesive board according to the shape and size of the location to be pasted, and prepare the above-mentioned vibration testing device for rocket engines;

[0018] Step 3: Calculate the required shim height T based on the angle θ between the extensions of the two tangents. Tighten the shim of height T onto the stud, and then tighten the vibration measuring block onto the stud, so that the bottom of the vibration measuring block is in close contact with the shim.

[0019] Step 4: Attach the adhesive board to the desired location, ensuring that the angle between the centerline of one of the four sides of the vibration measuring block and the thrust direction of the rocket engine is δ. The angle δ must satisfy the following condition:

[0020] 0°≤δ≤30°;

[0021] If the included angle δ does not meet the above conditions, then the position of the vibration measuring block (4) tightened on the stud is finely adjusted so that the included angle δ meets the above conditions, and then step 5 is executed.

[0022] If the included angle δ satisfies the above conditions, then proceed directly to step 5;

[0023] Step 5: Establish a standard coordinate system (x, y, z) with the engine thrust direction as the x-direction and the y and z directions perpendicular to the x-direction;

[0024] Step 6: Install the test sensor, start the test, and determine the measured coordinates (x, y) of the center of the vibration measuring block in the standard coordinate system. ′ y ′ , z ′ ), to obtain the measured vector of the vibration measuring block.

[0025] Step 7: Calculate the measured coordinates (x, y) of the vibration measuring block. ′ y ′ , z ′ The vectors in the three directions are projected onto the standard coordinate system and then normalized to obtain the corrected vectors.

[0026]

[0027] Where R is the rotation matrix;

[0028] Step 8: Based on the correction vector Calculate the vibration frequency and amplitude of the rocket engine and complete the vibration test.

[0029] Furthermore, in step 4, the formula for calculating the height T of the gasket is as follows:

[0030]

[0031] Where D is the diameter of the threaded stud;

[0032] d represents the diameter of the solid stud without threads.

[0033] Furthermore, in step 7, the calculation process of the rotation matrix R includes the following steps:

[0034] Step S1: Based on the standard coordinate system (x, y, z) and the measured coordinates (x′, y′, z′), determine the deviation angles α, β, and γ of the measured coordinate system relative to the standard coordinate system in the x, y, and z directions, respectively.

[0035] Step S2: Calculate the rotation matrix R in each of the three directions. x(α) R y(β) R z(γ)

[0036]

[0037] Step S3: Calculate the rotation matrix R

[0038] R = R x(α) ×R y(β) ×R z(γ) .

[0039] Compared with the prior art, the present invention has the following beneficial technical effects:

[0040] 1. This invention provides a vibration testing device for rocket engines, which adds an adhesive plate structure to increase the contact area between the bonding location and the vibration measuring block, thereby improving bonding stability. Furthermore, adhesive plate structures of different shapes are designed according to the shape of the bonding location to ensure seamless bonding between the adhesive plate and the contact surface, increasing the contact area and improving bonding stability to ensure long-term stable operation. This also allows the vibration measuring block to adapt to more application scenarios, improving the versatility and flexibility of the equipment.

[0041] 2. This invention provides a vibration testing device for rocket engines. By incorporating a shim structure between the adhesive plate and the vibration measuring block, and screwing the shim into the bottom of the stud to secure it tightly against the adhesive plate, the vibration measuring block can be more stably fixed. Furthermore, the tightening of the shim prevents loosening between the vibration measuring block and the adhesive plate, improving the stability of the vibration measuring block. Moreover, by adjusting the height of the shim, the vibration measurement requirements of the shape to be adhered to can be met, making the process convenient and quick, and resulting in more stable vibration measurement data.

[0042] 3. The present invention provides a vibration testing device for rocket engines. By opening threaded holes at the center of the six sides of the vibration measuring block for connecting to studs and test sensors, the installation method is simple. When the vibration measuring block is tightened on the studs, its bottom surface is in close contact with the gasket, and the test sensor is tightened on its top surface. The test sensor and the gasket clamp the vibration measuring block, thereby improving the stability of the vibration measuring block.

[0043] 4. The present invention provides a vibration testing device for rocket engines, wherein the threaded holes on two opposite sides of the six faces of the vibration measuring block are rotated in opposite directions, and when the test sensor is tightened, its connecting screw abuts against the stud, effectively avoiding the problem of the vibration measuring block loosening due to rotation in the same direction during the test, making the vibration measuring block more stable during the test, and making the clamping of the test sensor and the gasket on the vibration measuring block more secure.

[0044] 5. This invention provides a vibration testing device for rocket engines, which has a simple structure and can be pasted without the need for specialized tools. Due to its high stability and adhesion, it reduces the risk of vibration testing blocks falling off, lowers maintenance costs and downtime, improves the stability and adaptability of the equipment, reduces development costs, and provides strong support for the stable operation of mechanical vibration equipment.

[0045] 6. The present invention provides a vibration testing method for rocket engines, which obtains a corrected vector by normalizing the measured vector, and then calculates the engine vibration frequency and amplitude, thereby making the test data more accurate and improving the test precision. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of an embodiment of a vibration testing device for rocket engines according to the present invention;

[0047] Figure 2 This is a schematic diagram of the connection structure between the adhesive plate and the stud in an embodiment of a vibration testing device for a rocket engine according to the present invention;

[0048] Figure 3 for Figure 2 Top view;

[0049] Figure 4 This is a schematic diagram of the structure of the vibration measuring block in an embodiment of a vibration testing device for rocket engines according to the present invention;

[0050] Figure 5 This is a schematic diagram of the structure of a gasket in an embodiment of a vibration testing device for a rocket engine according to the present invention;

[0051] Figure 6 This is a schematic diagram of the orthographic projection of the adhesive plate in an embodiment of a vibration testing device for rocket engines according to the present invention.

[0052] The annotations in the attached figures are explained as follows:

[0053] 1. Adhesive board; 2. Stud; 3. Washer; 4. Vibration measuring block; 401. Threaded hole. Detailed Implementation

[0054] To make the objectives, advantages, and features of the present invention clearer, the vibration testing device and method for rocket engines proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0055] like Figures 1-5As shown, a vibration testing device for rocket engines is characterized by comprising an adhesive plate 1, studs 2, gaskets 3, and a vibration measuring block 4. A micro-textured structure is provided on the lower surface of the adhesive plate 1, increasing the contact area between the adhesive plate 1 and the adhesive, and improving the adhesion between the adhesive plate and the bonding location. This surface treatment technology further enhances the fixing effect of the vibration measuring block, ensuring long-term stable operation.

[0056] The stud 2 is located at the center of the upper surface of the adhesive plate 1, and its bottom is fixedly connected to the adhesive plate 1; in this embodiment, the fixed connection is achieved by welding.

[0057] The vibration measuring block 4 has threaded holes 401 at the center of each of its six sides. The vibration measuring block 4 is connected to the stud 2 through these threaded holes 401. The remaining threaded holes 401 are used to install test sensors. A gasket 3 is located between the adhesive plate 1 and the vibration measuring block 4 and is threadedly connected to the stud 2. The threads of the threaded holes on the two opposite sides of the vibration measuring block 4 have opposite directions. The test sensor has a connecting screw, which is connected to the vibration measuring block 4 through the threaded hole 401. After the test sensor is tightened, the connecting screw abuts against the stud. On the opposite side of the vibration measuring block connected to the stud, a test sensor is installed. This test sensor, connected by reverse threads, cooperates with the gasket 3 to effectively clamp the vibration measuring block 4. Even if vibration occurs during testing, because the threads on the two opposite sides have opposite directions, one side of the connection will always be tightened, increasing the stability of the vibration measuring block 4.

[0058] The shape of the adhesive board 1 is adapted to the shape of the location to be pasted; the pasting area of ​​the adhesive board can be calculated based on the vibration intensity and vibration time.

[0059] like Figure 6 As shown, the adhesive board 1 is projected onto the orthographic projection plane, and tangents are drawn at both ends of the bending extension direction of the adhesive board 1. The angle between the extensions of the two tangents is defined as θ, where 10°≤θ≤180°.

[0060] This invention also provides a vibration testing method for rocket engines, characterized by comprising the following steps:

[0061] Step 1: Determine the thrust direction of the rocket engine and, based on the vibration test requirements, determine the location where the vibration measurement block will be pasted.

[0062] Step 2: Determine the shape and size of the adhesive board 1 according to the shape and size of the location to be pasted, and prepare the above-mentioned vibration testing device for rocket engines;

[0063] Step 3: Calculate the required height T of the shim 3 based on the value of the angle θ between the extensions of the two tangents. Tighten the shim 3 of height T onto the stud 2, and then tighten the vibration measuring block 4 onto the stud 2 so that the bottom of the vibration measuring block 4 is in close contact with the shim 3.

[0064] Step 4: Attach the adhesive plate 1 to the position to be attached, so that the angle between the axis of one of the four sides of the vibration measuring block 4 and the thrust direction of the rocket engine is δ, and the angle δ satisfies the following condition: 0°≤δ≤30°;

[0065] If the included angle δ does not meet the above conditions, the position of the vibration measuring block (4) tightened on the stud is finely adjusted so that the included angle δ meets the above conditions, and then step 5 is executed; when the position to be pasted is highly restricted, there may be a situation where the included angle δ cannot meet the above conditions. In this case, the height of the shim 3 can be finely adjusted within the allowable range of the shim height, or the vibration measuring block 4 can be finely adjusted by slightly loosening it. Since the threaded connection between the vibration measuring block 4 and the stud is relatively tight, slightly loosening the vibration measuring block 4 will not affect the vibration measurement effect.

[0066] If the included angle δ satisfies the above conditions, then proceed directly to step 5;

[0067] The formula for calculating the height T of gasket 3 is as follows:

[0068]

[0069] Where D is the diameter of the threaded stud 2;

[0070] d represents the diameter of the solid stud without threads.

[0071] In addition, by designing shims of different thicknesses, the required number and thickness combination of shims can be determined according to the required height T of the shim 3, which can meet different vibration measurement needs.

[0072] Step 5: Establish a standard coordinate system (x, y, z) with the engine thrust direction as the x-direction and the y and z directions perpendicular to the x-direction;

[0073] Step 6: Install the test sensor, start the test, and determine the measured coordinates (x, y) of the center of the vibration measuring block 4 in the standard coordinate system. ′ y ′ , z ′ ), to obtain the measured vector of vibration measuring block 4.

[0074] Step 7: Calculate the measured coordinates (x, y) of the vibration measuring block. ′ y ′ , z ′The vectors in the three directions are projected onto the standard coordinate system and then normalized to obtain the corrected vectors.

[0075]

[0076] Where R is the rotation matrix;

[0077] The calculation process of the rotation matrix R includes the following steps:

[0078] Step S1: Based on the standard coordinate system (x, y, z) and the measured coordinates (x, y, z) ′ y ′ , z ′ Determine the deviation angles α, β, and γ of the measured coordinate system relative to the standard coordinate system in the x, y, and z directions, respectively.

[0079] Step S2: Calculate the rotation matrix R in each of the three directions. x(α) R y(β) R z(γ)

[0080]

[0081] Step S3: Calculate the rotation matrix R

[0082] R = R x(α) ×R y(β) ×R z(γ) .

[0083] Step 8: Based on the correction vector Calculate the vibration frequency and amplitude of the rocket engine and complete the vibration test.

[0084] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A vibration testing device for rocket engines, characterized in that: Includes adhesive board (1), stud (2), gasket (3) and vibration measuring block (4); The stud (2) is located at the center of the upper surface of the adhesive plate (1), and its bottom is fixedly connected to the adhesive plate (1); The vibration measuring block (4) has threaded holes (401) at the center of each of its six sides. One side of the vibration measuring block (4) is connected to the stud (2) through the threaded hole (401), and the remaining threaded holes (401) are used to install the test sensor. The gasket (3) is located between the adhesive plate (1) and the vibration measuring block (4), and is threadedly connected to the stud (2); The shape of the adhesive board (1) is adapted to the shape of the position to be pasted; The adhesive plate (1) is projected onto the orthographic projection plane. Tangents are drawn at both ends of the bending extension direction of the adhesive plate (1). The angle between the extensions of the two tangents is defined as θ, then 10°≤θ≤180°.

2. The vibration testing device for rocket engines according to claim 1, characterized in that: The lower surface of the adhesive plate (1) has a microtexture.

3. The vibration testing device for rocket engines according to claim 1, characterized in that: The threads of the threaded holes on the two opposite faces of the vibration measuring block (4) are in opposite directions; The test sensor has a connecting screw, which is connected to the vibration measuring block (4) through a threaded hole (401), and after the test sensor is tightened, the connecting screw abuts against the stud.

4. A vibration testing method for rocket engines, characterized in that, Includes the following steps: Step 1: Determine the thrust direction of the rocket engine and, based on the vibration test requirements, determine the location where the vibration measurement block will be pasted. Step 2: Determine the shape and size of the adhesive board (1) according to the shape and size of the location to be pasted, and prepare a vibration testing device for rocket engines as described in claim 1; Step 3: Calculate the required height T of the shim (3) based on the value of the angle θ between the extensions of the two tangents. Tighten the shim (3) with height T onto the stud (2), and then tighten the vibration measuring block (4) onto the stud (2) so that the bottom of the vibration measuring block (4) is in close contact with the shim (3). Step 4: Attach the adhesive plate (1) to the position to be attached, so that the angle between the axis of one of the four sides of the vibration measuring block (4) and the thrust direction of the rocket engine is δ, and the angle δ satisfies the following conditions: 0°≤δ≤30°; If the included angle δ does not meet the above conditions, then the position of the vibration measuring block (4) tightened on the stud is finely adjusted so that the included angle δ meets the above conditions, and then step 5 is executed. If the included angle δ satisfies the above conditions, then proceed directly to step 5; Step 5: Establish a standard coordinate system (x, y, z) with the engine thrust direction as the x-direction and the y and z directions perpendicular to the x-direction; Step 6: Install the test sensor, start the test, determine the measured coordinates (x′, y′, z′) of the center of the vibration measuring block (4) in the standard coordinate system, and obtain the measured vector of the vibration measuring block (4). Step 7: Project the measured coordinates (x′, y′, z′) of the vibration measuring block in the three directions onto the standard coordinate system, and perform unit vector normalization to obtain the correction vector. Where R is the rotation matrix; Step 8: Based on the correction vector Calculate the vibration frequency and amplitude of the rocket engine and complete the vibration test.

5. The vibration testing method for rocket engines according to claim 4, characterized in that, In step 4, the formula for calculating the height T of the gasket (3) is as follows: Where D is the diameter of the threaded stud (2); d is the diameter of the stud (2) solid column without threads.

6. The vibration testing method for rocket engines according to claim 4, characterized in that, In step 7, the calculation process of the rotation matrix R includes the following steps: Step S1: Based on the standard coordinate system (x, y, z) and the measured coordinates (x′, y′, z′), determine the deviation angles α, β, and γ of the measured coordinate system relative to the standard coordinate system in the x, y, and z directions, respectively. Step S2: Calculate the rotation matrix R in each of the three directions. x(α) R y(β) R z(γ) Step S3: Calculate the rotation matrix R R=R x(α) ×R y(β) ×R z(γ) 。

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