A high modal low resonance response test device and use method

Abstract

The present invention discloses a high modal low resonance response test device and a method for using the same. The test device includes a base plate, a support, and a positioning and clamping device. The support adopts an overall high-rigidity structure + a local thin-walled structure, that is, a structure composed of a thickened base and a single ear piece. The locally thin-walled single ear piece adopts a large fillet to transition to the thickened base. The support and the base plate of the test device are fixed with cylindrical pins, and a fixing force is applied from one side of the double-ear piece structure of the specimen. Using the test device of the present invention, the double ear piece can be fixed from one side, which is not only simple and quick to operate, but also does not generate bending stress on the double ear piece, simulating the actual installation situation, while having a higher natural frequency to meet the test requirements.

Description

Technical Field

[0001] The present invention belongs to the technical field of aviation environment testing, and in particular to a high-modal low-resonance response testing device and a use method thereof. Background Art

[0002] During aviation environmental tests, especially vibration tests, the vibration test fixture serves as the connecting component between the test piece and the vibration table. It receives vibration input from the vibration table and needs to transmit controllable output to the test piece. At the same time, the test device should be able to simulate actual installation conditions and ensure that the installation point is consistent with the actual connection point.

[0003] Because vibration tests on airborne equipment operate within a frequency range of 5 to 2000 Hz, the test setup must accurately transmit the vibration values ​​from the shaker table. According to Sandia Laboratories design specifications, specimen weights must range from 7 to 22 kg, and resonance is prohibited below 800 Hz. This means the first-order mode of the test setup must be greater than 800 Hz.

[0004] During the vibration test, a specimen weighing 20 kg ± 0.5 kg after filling with oil is fixed to three 8 mm thick structural beam lugs equipped with spherical plain bearings. The vibration test device should simulate the actual installation area of ​​the specimen on the aircraft.

[0005] The usual test device uses Figure 13 The structure involved a lug with a center height of 112mm from the vibration table surface (height-to-thickness ratio > 10). Due to the high component height, thin lug thickness, and heavy specimen, the first-order mode of the test apparatus fell below 400Hz after specimen loading. This directly led to severe resonance during the vibration test, causing the specimen's vibration input to deviate significantly from the required test input. When structural damage (to both lugs) occurred after the vibration test, it was difficult to distinguish whether the damage was due to a defect in the specimen itself or to the low-frequency resonance of the test apparatus.

[0006] At the same time, the specimen fixing part is a double-ear structure, such as Figure 11 and Figure 12 As shown in the figure, the method of clamping the front and rear ears of the specimen will apply a force that causes the ears to bend inward while fixing. This force can easily cause the ears to fracture. The two arrows in the figure indicate the direction of the bending stress. Summary of the Invention

[0007] The present invention aims to provide a high modal low resonance response test device and a method of use, which can simulate the actual installation situation of a thin-walled ear piece with a typical structure without increasing the thickness of the ear piece, while having a higher natural frequency to meet the test requirements.

[0008] The basic idea of ​​the present invention is: overall high-rigidity structure + local thin-wall structure, the local thin wall adopts large rounded transition, the support and the bottom plate of the test device are fixed with cylindrical pins, and the fixing force is applied from one side of the double-ear structure of the specimen.

[0009] The present invention is achieved through the following technical solutions:

[0010] A high-modal, low-resonance response test device is used to connect a vibration table and a test piece. The test piece has multiple sets of double-ear structures with non-parallel ear hole axes. In each set of double-ear structures, one ear has two connection holes, one of which is a threaded hole. A spherical bearing is installed between the two ears in the double-ear structure. The high-modal, low-resonance response test device includes:

[0011] A bottom plate, the bottom plate is connected to the vibration table and has a cylindrical pin hole;

[0012] The support comprises a base, a thickened base and a single ear piece, wherein a cylindrical pin hole is opened on the base, and the base is plugged into the cylindrical pin hole of the bottom plate through a cylindrical pin in the cylindrical pin hole, the thickened base extends upward from the upper end surface of the base, and the thickness and width of the thickened base are both greater than the thickness and width of the single ear piece, the single ear piece is connected to the thickened base, and the surface of the connection is an arc transition surface, and a joint bearing is assembled in the ear hole of the single ear piece;

[0013] The positioning and clamping device includes a connecting plate and a main positioning shaft. The connecting plate is provided with a connecting through hole and a notch. One surface of the connecting plate forms a limiting end face. The main positioning shaft is inserted into the connecting through hole, and the fastening screw is inserted into the notch.

[0014] As an option, the base plate and the support are positioned by cylindrical pins and cylindrical pin holes and then connected by bolts.

[0015] As an option, the thickened base is provided with an L-shaped notch or a U-shaped notch.

[0016] When an L-shaped notch is provided on the thickened base, the single ear piece is connected to the L-shaped notch of the thickened base, and the connection outline is an L-shaped outline;

[0017] When a U-shaped notch is provided on the thickened base, the single ear piece is connected in the U-shaped notch of the thickened base, and the connection outline is a U-shaped outline;

[0018] Different thickened base forms are selected according to different positions of the support.

[0019] As an option, the main positioning shaft is a variable-section shaft, and the cross-sectional outer diameter of the main positioning shaft gradually decreases from the limiting end face to the end of the main positioning shaft, and the length of the main positioning shaft is greater than the distance between the two ears in the double-ear structure.

[0020] As an option, the outer diameter of one of the multiple cross sections of the main positioning shaft is equal to the inner hole diameter of the spherical bearing.

[0021] As an option, the base plate is provided with a plurality of cylindrical pin holes perpendicular to the base plate, and each of the supports is plugged into and positioned with the base plate by three cylindrical pins.

[0022] A method for using the aforementioned high modal low resonance response test device comprises:

[0023] Step 1: Insert the support into the base plate through the cylindrical pin and then fix it with bolts;

[0024] Step 2: Move the specimen downward from the support until the single ear piece on the support is correctly inserted between the two ears of the double ear piece structure at the corresponding position on the specimen;

[0025] Step 3: Insert the main positioning shaft in the positioning and clamping device into the non-threaded connection hole in the double-ear structure until the upper limit end surface of the connecting piece is pressed against the surface of the ear on that side. Then, rotate the connecting piece around the main positioning shaft until the notch is aligned with the threaded connection hole in the double-ear. Then, insert the fastening screw through the notch of the connecting piece and screw it into the threaded connection hole in the double-ear.

[0026] Step 4, performing a vibration test on the specimen;

[0027] Step 5: After the test is completed, loosen the fastening screws, rotate the connecting piece around the main positioning axis until the notch is disengaged from the fastening screws, and remove the positioning and clamping device.

[0028] Furthermore, in step 3, the connecting hole of the ear piece on the side facing the operator in the double ear piece structure on the test piece is selected to be inserted into the main positioning shaft.

[0029] Compared with the prior art, the present invention has the following characteristics:

[0030] 1. High-rigidity structure. The support adopts a structure composed of a thickened base and a single ear piece. The thickened base improves the rigidity of the entire support structure by increasing the thickness, while the single ear piece realizes the correct connection with the real double-ear piece structure on the specimen. A single support has an overall high-rigidity structure and local dimensions according to the actual use environment. The transition surface between the thickened base and the single ear piece adopts a large rounded transition.

[0031] 2. Reference conversion structure: the cylindrical pin hole of a single support is both the processing reference of the single support and the installation reference of each support. At the same time, it cooperates with the cylindrical pin hole and cylindrical pin on the base plate to achieve high-precision installation of the support on the base plate, ensuring that the single ear piece, positioning and clamping device and double ear piece structure can be installed correctly, and there will be no situation where only part of the multiple double ear piece structures can be correctly connected due to misalignment (insufficient precision).

[0032] 3. Same-side positioning and single-side clamping structure. The main positioning shaft is inserted from one side, which is convenient for the operator. The clamping is also applied from the same side, avoiding the bending stress deformation and fracture problems caused by the traditional double-sided fastening method.

[0033] 4. The resonance problem is avoided by thickening the base, meeting the requirement that the first-order mode of the test device should be greater than 800 Hz. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the high modal low resonance response test device;

[0035] Figure 2 This is the front view of the high modal low resonance response test device, where the dotted line represents the test piece;

[0036] Figure 3 for Figure 2 The top view of the specimen is shown in Figure 1, where the dotted line represents the specimen;

[0037] Figure 4 This is a structural diagram of a high-modal support with an L-shaped notch;

[0038] Figure 5 This is a structural diagram of a high-modal support with a U-shaped notch;

[0039] Figure 6 for Figure 5 Multiple views of a high modal support with a U-shaped notch;

[0040] Figure 7 Multiple views for positioning the hold-down device;

[0041] Figure 8 Schematic diagram of the installation and disassembly process of the positioning and clamping device, support and specimen double ear piece;

[0042] Figure 9 A perspective view of three supports mounted on a base plate;

[0043] Figure 10 These are views of the specimen from two different directions, showing the double-ear structure at the connection and fixation point of the specimen;

[0044] Figure 11 Schematic diagram of the traditional specimen fork-ear fixed connection structure;

[0045] Figure 12 This is an enlarged view of the connection between the two-ear structure;

[0046] Figure 13 Schematic diagram of traditional support and base plate;

[0047] In the figure, 1-support; 2-positioning and pressing device; 11-base; 12-thickened base; 13-single ear piece; 21-connecting piece; 22-main positioning shaft; 23-slot. DETAILED DESCRIPTION

[0048] The present invention is further described below with reference to the accompanying drawings and specific embodiments. However, it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various modifications, substitutions and changes made according to common technical knowledge and customary means in the field are included in the scope of the present invention.

[0049] like Figures 1 to 9 As shown, the high modal low resonance response test device includes three components, a base plate, a support 1 and a positioning and pressing device 2, wherein the base plate is connected to the vibration table and has a cylindrical pin hole; the support 1 includes a base 11, a thickened base 12 and a single ear piece 13, wherein the base 11 has a cylindrical pin hole, and the base 11 is plugged into the cylindrical pin hole of the base plate through the cylindrical pin in the cylindrical pin hole, and the thickened base 12 extends upward from the upper end surface of the base 11, and the thickness and width of the thickened base 12 are greater than the single ear piece 13 The thickness and width of the single ear piece 13 are connected to the thickened base 12, and the surface of the connection is a circular arc transition surface. A joint bearing is assembled in the ear hole of the single ear piece 13; the positioning and clamping device 2 includes a connecting piece 21 and a main positioning shaft 22. The connecting piece 21 is provided with a connecting through hole and a notch 23. One surface of the connecting piece 21 forms a limiting end face, the main positioning shaft 22 is inserted into the connecting through hole, and the notch 23 is inserted into a fastening screw. The fastening screw is a connecting piece when the double ear piece structure is actually installed.

[0050] like Figures 4 to 6 An L-shaped notch or a U-shaped notch is provided on the thickened base 12. When an L-shaped notch is provided on the thickened base 12, the single ear piece 13 is connected to the L-shaped notch of the thickened base 12, and the connection outline is an L-shaped outline line; when a U-shaped notch is provided on the thickened base 12, the single ear piece 13 is connected to the U-shaped notch of the thickened base 12, and the connection outline is a U-shaped outline line.

[0051] like Figure 7 As shown, the main positioning shaft 22 in the positioning and clamping device 2 is divided into three sections at the shaft section located on the left side of the limiting end face, and the outer diameters of the three sections gradually decrease. The outer diameter of the middle section is equal to the inner hole diameter of the joint bearing in the ear hole of the single ear piece 13. When the main positioning shaft 22 is inserted, ensure that this section is matched with the inner hole of the joint bearing.

[0052] like Figure 10 There are three groups of double-ear plate structures on the surface of the specimen whose ear hole axes are not all parallel. In each group of double-ear plate structures, one ear plate has two connecting holes, one of which is a threaded hole.

[0053] like Figure 8 The main positioning shaft 22 is inserted into the double ear piece of the test product, and the middle part of the main positioning shaft 22 is inserted into the ear hole joint bearing of the single ear piece 13 of the support 1. The limiting end face is close to the double ear piece side of the test product. Tighten the fixing screws to achieve the connection between the positioning and clamping device 2 and the double ear piece structure of the test product.

[0054] The vibration test includes the following steps:

[0055] Step 1: Insert the support 1 into the base plate through the cylindrical pin and then fix it with bolts;

[0056] Step 2, move the test piece downward from the support 1 until the single ear piece (13) on the support 1 is correctly inserted between the two ear pieces of the double ear piece structure at the corresponding position on the test piece;

[0057] Step 3: Insert the main positioning shaft 22 in the positioning and pressing device 2 into the non-threaded connection hole in the double-ear structure until the upper limit end surface of the connecting piece 21 is pressed against the surface of the ear on that side (at this time, the main positioning shaft 22 simultaneously penetrates the double-ear structure and the joint bearing in the single ear 13), then rotate the connecting piece 21 with the main positioning shaft 22 as the axis until the notch 23 is aligned with the threaded connection hole in the double-ear, and then pass the fastening screw through the notch 23 of the connecting piece 21 and screw it into the threaded connection hole in the double-ear;

[0058] Step 4, performing a vibration test on the specimen;

[0059] Step 5: After the test is completed, loosen the fastening screws, rotate the connecting piece 21 around the main positioning shaft 22 until the notch 23 is disengaged from the fastening screws, and remove the positioning and pressing device 2.

[0060] In the above step 3, the connecting hole of the ear piece on the side facing the operator in the double ear piece structure of the test piece is selected and inserted into the main positioning shaft 22 .

[0061] 1. Support 1 is secured to the base plate of the test device using cylindrical pins. Due to the complex spatial relationships between the double-ear and single-ear pieces 13, the cylindrical pin holes on support 1 serve as both the machining and installation datums for support 1, ensuring high precision in terms of shape, size, and spatial relationships. For example, the pin holes of each single-ear piece 13 on support 1 have an H7 / h6 fit with the double-ear piece structure of the test specimen, with a tolerance of 0.029. The dimensions between the pin holes are precisely 0.001. Inadequate machining and assembly precision for each support 1 can directly result in the test product being unable to be installed. Three perpendicular cylindrical pin holes (with an H7 precision) are bored into the base 11 of each support 1 (i.e., their axes are parallel, and the line connecting the center points of the holes on the surface of the base 11 forms a right angle). These holes form a coordinate system for machining and measurement. The corresponding cylindrical pin holes on the base plate serve as assembly coordinates, ensuring the accuracy of machining, measurement, and installation of support 1.

[0062] 2. The positioning and clamping device 2 is installed from one side of the double-ear structure and fixed to the specimen on the same side to avoid clamping the double-ears of the specimen inward at the same time. Figure 11 、 12 13. After the test product is installed, the fasteners need to be tightened. When the bolt head and nut are respectively on different sides of the double ear piece of the test product, if the bolt and nut are not tightened, they will loosen during the reciprocating motion of the vibration test; if tightened, the wrench will have a large force arm, which will apply an inward clamping force to the double ear piece during the tightening process. Under the action of large test values, the double ear piece of the test product is very likely to crack at the root of the ear piece. At the same time, this fixing method is inconsistent with the actual use conditions. After failure occurs, it is not enough to ensure that the test fully simulates the actual use environment and the experimental results are true and valid. The method of fastening screws combined with the main positioning shaft used in the present invention is closer to the actual installation situation (the two connection holes on the double ear piece are used in actual installation). Among them, the fastening screws are part of the actual installation structure and match the threaded connection holes. Furthermore, the fastening screws on the test piece do not need to be removed, but only need to be tightened or loosened. Because when the connecting piece 21 is rotated, the notch 23 will disengage the fastening screws, realizing quick disassembly and installation.

[0063] Pressing the double ear piece of the tested product on one side will not cause the double ear piece to be simultaneously subjected to the same Figure 12 The inward pressing force indicated by the double arrow in the middle ensures that the single ear piece 13 of the double ear piece under test is tightly attached to the support 1 from one side and will not loosen axially.

[0064] 3. The support 1 is widened and thickened as a whole by thickening the base 12, becoming a high-rigidity structure. The part connected to the test piece is still designed according to the actual size of the machine (i.e. the single ear piece 13 and the spherical bearing), and a large fillet transition is used between the two. Figure 4 and Figure 5 As shown in Figure 2, the first-order natural frequency of this structure is calculated by Ansys software to be greater than 1000Hz.

[0065] The above embodiments are not intended to limit the protection scope of the present invention. Any variations, modifications or equivalent substitutions made on the basis of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A high modal low resonance response test device for connecting a vibration table to a test piece, wherein the test piece has multiple sets of double-ear structures with non-parallel ear hole axes, and one ear piece in each set of double-ear structures has two connection holes, one of which is a threaded hole, characterized in that: High modal low resonance response test equipment includes: A bottom plate, the bottom plate is connected to the vibration table and has a cylindrical pin hole; A support (1), the support (1) comprising a base (11), a thickened base (12) and a single ear piece (13), wherein a cylindrical pin hole is opened on the base (11), the base (11) is plugged into the cylindrical pin hole of the bottom plate through a cylindrical pin in the cylindrical pin hole, the thickened base (12) extends upward from the upper end surface of the base (11), and the thickness of the thickened base (12) is greater than the thickness of the single ear piece (13), the width of the thickened base (12) is greater than the width of the single ear piece (13), the single ear piece (13) is connected to the thickened base (12), and the surface of the connection is an arc transition surface, and a joint bearing is assembled in the ear hole of the single ear piece (13); A positioning and clamping device (2) includes a connecting piece (21) and a main positioning shaft (22), wherein the connecting piece (21) is provided with a connecting through hole and a notch (23), a surface of the connecting piece (21) forms a limiting end face, the main positioning shaft (22) is inserted into the connecting through hole, and a fastening screw is inserted into the notch (23).

2. A high modal low resonance response test device according to claim 1, characterized in that: The base plate and the support (1) are positioned by cylindrical pins and cylindrical pin holes and then connected by bolts.

3. The high modal low resonance response test device according to claim 1, characterized in that: The thickened base (12) is provided with an L-shaped notch or a U-shaped notch. When an L-shaped notch is provided on the thickened base (12), the single ear piece (13) is connected to the L-shaped notch of the thickened base (12), and the connection profile is an L-shaped profile line; When a U-shaped notch is provided on the thickened base (12), the single ear piece (13) is connected in the U-shaped notch of the thickened base (12), and the connection profile is a U-shaped profile line.

4. The high modal low resonance response test device according to claim 1, characterized in that: The main positioning shaft (22) is a variable-section shaft, and the cross-sectional outer diameter of the main positioning shaft (22) gradually decreases from the limiting end face toward the end of the main positioning shaft (22). The length of the main positioning shaft (22) is greater than the distance between the two ears in the double-ear structure.

5. The high modal low resonance response test device according to claim 4, characterized in that: The outer diameter of one of the multiple cross sections of the main positioning shaft (22) is equal to the inner hole diameter of the spherical bearing.

6. The high modal low resonance response test device according to claim 1, characterized in that: The base plate is provided with a plurality of cylindrical pin holes perpendicular to the base plate, and each of the supports (1) is plugged into and positioned with the base plate via three cylindrical pins.

7. A method for using the high modal low resonance response test device according to claim 1, characterized in that: include, Step 1: Insert the support (1) into the base plate through a cylindrical pin and then fix it with bolts; Step 2, move the test piece downward from the support (1) until the single ear piece (13) on the support (1) is correctly inserted between the two ear pieces of the double ear piece structure at the corresponding position on the test piece; Step 3, insert the main positioning shaft (22) in the positioning and pressing device (2) into the non-threaded connection hole in the double-ear structure until the upper limit end face of the connecting piece (21) is pressed against the surface of the ear on that side, and then rotate the connecting piece (21) with the main positioning shaft (22) as the axis until the notch (23) is aligned with the threaded connection hole in the double-ear, and then pass the fastening screw through the notch (23) of the connecting piece (21) and screw it into the threaded connection hole in the double-ear; Step 4, performing a vibration test on the specimen; Step 5: After the test is completed, loosen the fastening screws, rotate the connecting piece (21) with the main positioning shaft (22) as the axis until the notch (23) is disengaged from the fastening screws, and remove the positioning and clamping device (2).

8. The method of use according to claim 7, characterized in that: In step 3, the connecting hole of the ear piece on the side facing the operator in the double ear piece structure on the test piece is selected and inserted into the main positioning shaft (22).

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