A test structure and method for testing a test piece under static tensile stress and vibration fatigue

Abstract

The application belongs to the technical field of vibration fatigue test design, and particularly relates to a vibration fatigue test structure and method of a test piece under static tensile stress, wherein the vibration fatigue test structure of the test piece under static tensile stress comprises a vibration table, a support seat connected to the vibration table and provided with a support hole, a static loading block arranged in the support hole, a test piece with a test and evaluation part at a middle part, a fixed end cover plate connected to the support seat and used for tightly fixing one end of the test piece on the support seat, a loading end cover plate connected to the support seat and the static loading block and capable of sliding relative to the support seat, and used for tightly fixing the other end of the test piece on the static loading block, and an adjusting screw arranged on the support seat and threadedly connected to the static loading block, so that the static loading block can be driven to move along an axial direction of the test piece by screwing.

Description

Technical Field

[0001] This application belongs to the field of vibration fatigue test design technology, specifically relating to a test structure and method for vibration fatigue testing of test specimens under static tensile stress. Background Technology

[0002] In the engineering design process, in addition to considering static properties such as strength and stiffness, it is also necessary to consider the dynamic response under dynamic loads. This is especially true for the structural design of aircraft engines, where the dynamic response problem is even more prominent.

[0003] A significant number of aircraft structures are under high tensile stress levels during operation. However, current research on the impact of dynamic response mainly focuses on vibration fatigue, i.e., the dynamic stress induced by vibration on the structure and its effect on the vibration fatigue life of the structure. It does not introduce the corresponding static tensile stress, making it difficult to accurately determine the vibration fatigue life of the structure.

[0004] This application is made in view of the aforementioned technical deficiencies. Summary of the Invention

[0005] The purpose of this application is to provide a structure and method for testing vibration fatigue of a test specimen under static tensile stress, so as to overcome or mitigate at least one of the known technical defects.

[0006] The technical solution of this application is:

[0007] On the one hand, a vibration fatigue test structure for a specimen under static tensile stress is provided, comprising:

[0008] Vibration table;

[0009] The support base is connected to the vibration table and has support holes.

[0010] Static loading blocks are set in the support holes;

[0011] The middle part of the test specimen is the test evaluation part;

[0012] The fixed end cover plate is connected to the support base to press and fix one end of the test piece onto the support base;

[0013] The loading end cover plate is connected to the support base and the static loading block, and can slide relative to the support base to press and fix the other end of the test piece onto the static loading block.

[0014] The adjusting screw, mounted on the support base and threadedly connected to the static loading block, allows the static loading block to be moved axially along the test piece by turning it.

[0015] According to at least one embodiment of this application, in the above-described test structure for vibration fatigue testing of test specimens under static tensile stress, the fixed end cover plate connects the corresponding ends of the test specimen to the support base by three bolts;

[0016] The loading end cover is connected to the support base by two pairs of bolts, and the corresponding bolt holes on the loading end cover are strip holes extending along the axial direction of the test piece;

[0017] The loading end cover plate connects the corresponding ends of the test piece to the static loading block using three bolts.

[0018] On the other hand, a vibration fatigue test method for a specimen under static tensile stress is provided, implemented based on any of the above-mentioned vibration fatigue test structures for specimens under static tensile stress, including:

[0019] Strain-tensile stress calibration steps at the test site of the test specimen:

[0020] Strain gauges are attached to the far end of the test specimen and connected to a UEI strain acquisition device to collect strain data. The test specimen is clamped at both ends with a universal testing machine, and a load is applied to the test specimen. The strain at the far end of the test test part of the test specimen is collected. The tensile stress at the test part is calculated using the finite element model of the test specimen, and the strain-tensile stress curve at the far end of the test test part of the test specimen is plotted.

[0021] Tensile stress loading steps at the test sites of the test specimen:

[0022] Assemble the test specimen with the vibration table, support base, fixed end cover plate, loading end cover plate and its adjusting screw. By turning the adjusting screw, drive the static loading block to move along the axial direction of the test specimen. According to the strain-tensile stress curve of the far end of the test test part of the test specimen, generate the required tensile stress at the test test part of the test specimen.

[0023] Vibration fatigue testing steps at the test sites of the test specimen:

[0024] Start the vibration table and apply a vibration load to the test piece at the first natural frequency;

[0025] Test specimens The cyclic fatigue test involves stopping the machine every 1 hour to perform non-destructive testing on the test piece, inspecting the test assessment area of ​​the test piece, stopping the test when fracture failure occurs at the test assessment area of ​​the test piece, and recording the number of test cycles.

[0026] If the test piece is subjected to If no fracture failure occurs at the test site after cyclic fatigue testing, the amplitude at the test site is increased by 10%, and the test is then subjected to further testing. The cyclic fatigue test involves stopping the machine every hour to perform non-destructive testing on the test specimen. If fracture failure occurs at the test site, the test is stopped, and the number of test cycles is recorded. If fracture failure does not occur at the test site, the amplitude at the test site is increased by 10%, and the test is repeated. The cyclic fatigue test was conducted by stopping the machine every 1 hour to perform non-destructive inspection on the test piece. When the test piece failed at the test assessment location, the test was stopped and the number of test cycles was recorded. Based on this, the amplitude of the test piece required for the fatigue test was determined.

[0027] The test specimen is subjected to the amplitude required for fatigue testing. The cyclic fatigue test involves stopping the machine every 1 hour to perform non-destructive testing on the test piece, inspecting the test assessment area of ​​the test piece, and stopping the test when fracture failure occurs at the test assessment area of ​​the test piece, and recording the number of test cycles.

[0028] According to at least one embodiment of this application, in the above-described method for testing vibration fatigue of a test specimen under static tensile stress, in the strain-tensile stress calibration step at the test assessment location of the test specimen, the timestamp of the universal testing machine data is set to be consistent with the start of the timestamp of the UEI strain acquisition device data, and the force and strain at the same time point are associated.

[0029] According to at least one embodiment of this application, in the above-described method for testing vibration fatigue of a test specimen under static tensile stress, in the vibration fatigue assessment step at the test site of the test specimen, a laser vibration meter is used to measure the displacement of the calibration point at the test site of the test specimen. The controller is associated with the vibration table to control the displacement of the calibration point at the test site of the test specimen to remain unchanged, so as to maintain the amplitude of the test site of the test specimen. Strain gauges are used to measure the strain at the far end of the test site of the test specimen using a UEI strain acquisition device. Combined with the amplitude of the calibration point, the vibration stress at the test site of the test specimen is calculated using the finite element model of the test specimen.

[0030] According to at least one embodiment of this application, in the above-described method for testing vibration fatigue of a test specimen under static tensile stress, in the vibration fatigue assessment step at the test assessment location of the test specimen, the test specimen is subjected to non-destructive testing, specifically using an optical microscope, X-ray machine, or ultrasonic equipment to inspect the test assessment location of the test specimen.

[0031] According to at least one embodiment of this application, in the above-described method for testing vibration fatigue of a test specimen under static tensile stress, the data processing steps for the vibration fatigue assessment test of the test specimen are as follows:

[0032] The vibration fatigue life of the test specimen is evaluated at the test site. The x-axis represents the stress amplitude. Using the vertical axis as the ordinate, plot a cluster of SN curves under different stress ratios R.

[0033] According to at least one embodiment of this application, in the above-described method for testing vibration fatigue of a test specimen under static tensile stress, the step of processing the test data for vibration fatigue assessment of the test specimen further includes:

[0034] Take on the SN curve family Plot the points with the corresponding static tensile stress as the x-axis and the vibration stress as the y-axis. Isochronous lifetime curve.

[0035] This application has at least the following beneficial technical effects:

[0036] This invention provides a structure and method for vibration fatigue testing of test specimens under static tensile stress. Through the design of the support base, static loading block, fixed end cover plate, loading end cover plate, adjusting screw and test specimen, the corresponding static tensile stress can be simulated to be applied to the test test part of the test specimen during vibration fatigue testing, so as to accurately determine the vibration fatigue life. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the vibration fatigue test structure of the test specimen under static tensile stress provided in the embodiments of this application;

[0038] Figure 2 This is a strain-tensile stress curve of the far end of the test section of the test specimen provided in the embodiments of this application;

[0039] in:

[0040] 1-Vibration table; 2-Support base; 3-Static loading block; 4-Test piece; 5-Fixed end cover plate; 6-Loading end cover plate.

[0041] To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual size of the product. Furthermore, the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. Detailed Implementation

[0042] To make the technical solution and advantages of this application clearer, the technical solution of this application will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of this application, and are only used to explain this application, not to limit this application. It should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, and other related parts can be referred to the general design.

[0043] Furthermore, unless otherwise defined, the technical or scientific terms used in this application description shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms indicating direction used in this application description are used only to indicate relative direction or positional relationship; when the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "comprising" as used in this application description indicates that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, but does not exclude other elements or objects.

[0044] Furthermore, it should be noted that, unless otherwise explicitly specified and limited, terms such as "installation" and "connection" used in the description of this application should be interpreted broadly. For example, a connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand its specific meaning in this application according to the specific circumstances.

[0045] The following is in conjunction with the appendix Figures 1 to 2 This application will be described in further detail.

[0046] On the one hand, a vibration fatigue test structure for a specimen under static tensile stress is provided, such as Figure 1 As shown, it includes:

[0047] Vibration table 1;

[0048] Support base 2 is connected to vibration table 1 and has support holes;

[0049] Static loading block 3 is set in the support hole;

[0050] Test piece 4, the middle part is the test evaluation part;

[0051] The fixed end cover plate 5 is connected to the support base 2, and presses and fixes one end of the test piece 4 onto the support base 2;

[0052] The loading end cover plate 6 is connected to the support base 2 and the static loading block 3, and can slide relative to the support base 2 to press and fix the other end of the test piece 4 onto the static loading block 3.

[0053] An adjusting screw is set on the support 2 and threadedly connected to the static loading block 3 so that the static loading block 3 can be driven to move axially along the test piece 4 by turning it.

[0054] Based on the static tensile stress test structure of the test specimen under the above embodiment, the vibration fatigue test can be carried out by turning the adjusting screw to drive the static loading block 3 to move along the axial direction of the test specimen 4, pushing and pulling the test specimen 4, so that the required static tensile stress is generated at the test assessment part of the test specimen 4, restoring the static tensile stress subjected to the test assessment part of the test specimen 4 during vibration, and then starting the vibration table 1 to apply vibration load to the test specimen 4, and measuring the vibration fatigue life of the test specimen 4.

[0055] Regarding the vibration fatigue test structure for test specimens under static tensile stress disclosed in the above embodiments, those skilled in the art will understand that, through the cooperative design of the support base 2, static loading block 3, fixed end cover plate 5, loading end cover plate 6, adjusting screw and test specimen 4, the corresponding static tensile stress can be simulated and applied to the test assessment part on the test specimen 4 during vibration fatigue testing, thereby accurately determining the vibration fatigue life.

[0056] For the vibration fatigue test structure of the test specimen under static tensile stress disclosed in the above embodiments, the corresponding end of the test specimen 4 is pressed and fixed on the static loading block 3 by the loading end cover plate 6. The static loading block 3 is set in the support hole of the support base 2, and the loading end cover plate 6 is slidably connected to the support base 2. In this way, while ensuring that the static loading block 3 moves along the axial direction of the test specimen 4, the position of the static loading block 3 in the lateral and vertical directions of the test specimen 4 can be reliably constrained, so as to avoid generating additional lateral and vertical loads on the test specimen 4 and affecting the accuracy of the vibration fatigue test.

[0057] In some optional embodiments, in the above-described test structure for vibration fatigue testing of test specimens under static tensile stress, the fixed end cover plate 5 connects the corresponding end of the test specimen 4 to the support base 2 by three bolts;

[0058] The loading end cover plate 6 is connected to the support base 2 by two pairs of bolts, and the corresponding bolt holes on the loading end cover plate 6 are strip holes extending along the axial direction of the test piece 4;

[0059] The loading end cover plate 6 connects the corresponding end of the test piece 4 to the static loading block 3 by three bolts.

[0060] On the other hand, a vibration fatigue test method for specimens under static tensile stress is provided, which is implemented based on any of the above-mentioned vibration fatigue test structures for specimens under static tensile stress.

[0061] Strain-tensile stress calibration steps at the test site of the test specimen:

[0062] In vibration fatigue testing, stress concentration occurs at the test site of test piece 4. To avoid affecting the response of the test site and to ensure the accuracy of the test measurement, the tensile stress at the test site of test piece 4 cannot be measured directly. Instead, it needs to be determined by measuring the strain at the far end of the test site of test piece 4.

[0063] Strain gauges were attached to the distal end of the test site of specimen 4, and a UEI strain acquisition device was connected to collect strain data. A universal testing machine was used to clamp both ends of specimen 4, applying a load to it. The timestamps of the universal testing machine data and the UEI strain acquisition device data were synchronized, correlating the force and strain at the same time point. The strain at the distal end of the test site of specimen 4 was collected, and the tensile stress at the test site was calculated using the finite element model of the specimen. The strain-tensile stress curve at the distal end of the test site of specimen 4 was then plotted. In a specific example, such as... Figure 2 As shown.

[0064] Tensile stress loading steps at the test sites of the test specimen:

[0065] Assemble the test piece 4 with the vibration table 1, support base 2, fixed end cover plate 5, loading end cover plate 6 and its adjusting screw. By turning the adjusting screw, drive the static loading block 3 to move along the axial direction of the test piece 4. The strain-tensile stress curve at the far end of the test test part of the test piece 4 is obtained, so that the required tensile stress is generated at the test test part of the test piece 4, thereby realizing the loading of tensile stress at the test test part of the test piece 4.

[0066] Vibration fatigue testing steps at the test sites of the test specimen:

[0067] Start the vibration table 1 and apply a vibration load to the test piece 4 at the first natural frequency. Use a laser vibration meter to measure the displacement of the calibration point of the test piece 4. The controller is associated with the vibration table 1 to control the displacement of the calibration point of the test piece 4 to remain unchanged, thereby maintaining the amplitude of the test part of the test piece 4. Use strain gauges and UEI strain acquisition device to measure the strain at the test part of the test piece 4. Combine the amplitude of the calibration point and calculate the vibration stress of the test part of the test piece 4 using the finite element model of the test piece.

[0068] Test piece 4 was subjected to The cyclic fatigue test is conducted by stopping the machine every 1 hour to perform non-destructive inspection on the test piece 4. Specifically, an optical microscope, X-ray machine or ultrasonic equipment can be used to inspect the test assessment part of the test piece 4. When fracture failure occurs at the test assessment part of the test piece 4, the test is stopped and the number of test cycles is recorded, which is the vibration fatigue life of the test assessment part of the test piece 4.

[0069] If test piece 4 is subjected to After the cyclic fatigue test, if no fracture failure occurs at the test site of test piece 4, then the amplitude at the test site of test piece 4 is increased by 10%. Specifically, the amplitude at the fixed point on test piece 4 is increased by 10%. The cyclic fatigue test was conducted with the machine stopped every hour for non-destructive testing of test piece 4. The test was stopped when fracture failure occurred at the test assessment location of test piece 4, and the number of test cycles was recorded. If fracture failure did not occur at the test assessment location of test piece 4, the amplitude of the vibration at the assessment location of test piece 4 was increased by 10%, and the test was continued. The cyclic fatigue test was conducted by stopping the machine every 1 hour to perform non-destructive inspection on the test piece 4. When the test piece 4 failed at the test test location, the test was stopped and the number of test cycles was recorded. Based on this, the amplitude of the test piece 4 required for the fatigue test was determined.

[0070] Test specimen 4 was subjected to the amplitude required for fatigue testing. The cyclic fatigue test was conducted by stopping the machine every 1 hour to perform non-destructive testing on the test piece 4, checking the test assessment area of ​​the test piece 4, and stopping the test when fracture failure occurred at the test assessment area of ​​the test piece 4, and recording the number of test cycles.

[0071] Steps for processing vibration fatigue test data of test specimens:

[0072] Vibration fatigue life of test specimen 4 at the test site The x-axis represents the stress amplitude. Plot the stress ratios R= on the ordinate. The SN curve cluster below, among which, The minimum vibration stress at the test site of test piece 4 is [value missing]. The maximum vibration stress at the test site of test piece 4;

[0073] Take on the SN curve family Plot the points with the corresponding static tensile stress as the x-axis and the vibration stress as the y-axis. Isochronous lifetime curve.

[0074] The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to mutually. In the absence of conflict, the embodiments and technical features in the embodiments of this application can be combined to obtain new embodiments.

[0075] The technical solution of this application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A method for vibration fatigue testing of a specimen under static tensile stress, implemented based on a vibration fatigue testing structure for a specimen under static tensile stress, the vibration fatigue testing structure for a specimen under static tensile stress comprising: Vibration table (1); Support base (2) is connected to the vibration table (1) and has support holes; A static loading block (3) is set in the support hole; Test piece (4), the middle part is the test evaluation part; The fixed end cover plate (5) is connected to the support base (2) to press and fix one end of the test piece (4) onto the support base (2); The loading end cover plate (6) is connected to the support base (2) and the static loading block (3), and can slide relative to the support base (2) to press and fix the other end of the test piece (4) onto the static loading block (3); The adjusting screw is set on the support base (2) and threaded to the static loading block (3) so that the static loading block (3) can be moved axially along the test piece (4) by turning it. The method for vibration fatigue testing of test specimens under static tensile stress is characterized by comprising: Strain-tensile stress calibration steps at the test site of the test specimen: Strain gauges are attached to the far end of the test piece (4), and UEI strain acquisition device is connected to collect strain data. The two ends of the test piece (4) are clamped by a universal testing machine, and a load is applied to the test piece (4). The strain at the far end of the test test part of the test piece (4) is collected. The tensile stress of the test part is calculated by the finite element model of the test piece, and the strain-tensile stress curve at the far end of the test test part of the test piece (4) is plotted. Tensile stress loading steps at the test sites of the test specimen: Assemble the test piece (4) with the vibration table (1), support base (2), fixed end cover plate (5), loading end cover plate (6) and its adjusting screw. By turning the adjusting screw, drive the static loading block (3) to move along the axial direction of the test piece (4). According to the strain-tensile stress curve of the far end of the test test part of the test piece (4), generate the required tensile stress at the test test part of the test piece (4). Vibration fatigue testing steps at the test sites of the test specimen: Start the vibration table (1) and apply a vibration load to the test piece (4) at the first natural frequency; Test specimen (4) was subjected to The cyclic fatigue test was conducted by stopping the machine every 1 hour to perform non-destructive inspection on the test piece (4) and inspecting the test assessment part of the test piece (4). When the test assessment part of the test piece (4) fractured and failed, the test was stopped and the number of test cycles was recorded. If test piece (4) is subjected to After the cyclic fatigue test, if no fracture failure occurs at the test site of the test piece (4), the amplitude of the test site of the test piece (4) is increased by 10%, and the test is continued. The cyclic fatigue test was conducted by stopping the machine every hour to perform non-destructive testing on the test piece (4). When fracture failure occurred at the test assessment location of the test piece (4), the test was stopped and the number of test cycles was recorded. If fracture failure still did not occur at the test assessment location of the test piece (4), the amplitude of the test assessment location of the test piece (4) was increased by 10%, and the test was continued. The cyclic fatigue test was conducted by stopping the machine every 1 hour to perform non-destructive inspection on the test piece (4). When the test piece (4) failed at the test assessment location, the test was stopped and the number of test cycles was recorded. Based on this, the amplitude of the test piece (4) required for the fatigue test was determined. The test piece (4) was subjected to the amplitude required for the fatigue test. The cyclic fatigue test is performed by stopping the machine every 1 hour to perform non-destructive inspection on the test piece (4) and inspecting the test assessment part of the test piece (4). When the test failure occurs at the test assessment part of the test piece (4), the test is stopped and the number of test cycles is recorded.

2. The method for vibration fatigue testing of specimens under static tensile stress according to claim 1, characterized in that, In the strain-tensile stress calibration step at the test site of the test specimen, the timestamp of the universal testing machine data is set to be consistent with the timestamp of the UEI strain acquisition device data, so that the force and strain at the same time point are associated.

3. The method for vibration fatigue testing of specimens under static tensile stress according to claim 1, characterized in that, In the vibration fatigue test step at the test site of the test piece, a laser vibration meter is used to measure the displacement of the calibration point at the test site of the test piece (4). The controller is connected to the vibration table (1) to control the displacement of the calibration point at the test site of the test piece (4) to remain unchanged, so as to maintain the amplitude of the test site of the test piece (4). Strain gauges are used to measure the strain at the far end of the test site of the test piece (4) using a UEI strain acquisition device. Combined with the amplitude of the calibration point, the vibration stress of the test site of the test piece (4) is calculated using the finite element model of the test piece.

4. The method for vibration fatigue testing of specimens under static tensile stress according to claim 1, characterized in that, In the vibration fatigue test step at the test site of the test piece, the test piece (4) is subjected to non-destructive testing, specifically by using an optical microscope, X-ray instrument or ultrasonic equipment to test the test site of the test piece (4).

5. The method for vibration fatigue testing of specimens under static tensile stress according to claim 1, characterized in that, Also includes: Steps for processing vibration fatigue test data of test specimens: The vibration fatigue life of the test piece (4) is evaluated. The x-axis represents the stress amplitude. Using the vertical axis as the ordinate, plot a cluster of SN curves under different stress ratios R.

6. The method for vibration fatigue testing of a specimen under static tensile stress according to claim 5, characterized in that, The data processing steps for vibration fatigue testing of test specimens also include: Take on the SN curve family Plot the points with the corresponding static tensile stress as the x-axis and the vibration stress as the y-axis. Isochronous lifetime curve.

Images