A fatigue test fixture for typical angle connectors of bulkheads and its use method

Abstract

The present invention provides a fatigue test fixture for typical angle connectors of bulkheads and a method of use, which is particularly suitable for L-shaped connectors with design requirements for special cross-sections. The fixture includes a fixed box body, a side plate, a lever and a loading mechanism, wherein the fixed box body and the lever are vertically connected; the fixed box body is fixedly connected with a horizontal part and a side plate of the angle connector from bottom to top, and the side plate is fixedly connected to the horizontal part of the angle connector; the lever is provided with a groove, and the vertical part of the angle connector is fixed in the groove; the loading mechanism includes an upper loading component and a lower loading component, wherein the upper loading component is rotationally connected to the fixed box body, and the lower loading component is rotationally connected to the lever. During the loading process, the loading component connected to the angle connector will move with the displacement of the chuck of the testing machine, thereby correctly simulating the actual stress state of the angle connector. Its structural design is reasonable and the clamping is convenient, ensuring that the fatigue test of the connector with special design requirements for the loaded part is carried out smoothly.

Description

Technical Field

[0001] The invention belongs to the technical field of fixtures, and in particular relates to a fatigue test fixture and a test method for typical angle connectors of bulkheads, in particular for angle connectors of aircraft with load requirements. Background Art

[0002] Most of the angle connectors on the aircraft are subjected to alternating loads, and fatigue failure is the main failure mode. Therefore, it is very important to study the fatigue strength and fatigue life of the aircraft angle connectors through experiments. The fatigue performance experiment of the angle connector requires the angle connector test piece to be clamped on a specially designed fixture, and the fatigue test machine is used to load the fixture to finally obtain the fatigue strength, fatigue life, failure mode and other mechanical properties of the sample. Therefore, it is crucial for the accuracy of the experimental results that the experimental fixture correctly simulates the mechanical properties of the aircraft in flight.

[0003] The tensile test fixture is a device that clamps the sample, transmits longitudinal tension to the sample, and causes elastic or plastic tensile deformation of the sample. Due to the small size of the angle connector, if it is directly installed on the tensile machine, the existing tensile test machine fixture is prone to sickle deformation, loss of clamping force, slipping, etc. during the tensile test. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a fatigue test fixture and test method for typical angle connectors of bulkheads, which ensure that the angle connectors are clamped on a standard fatigue testing machine, with accurate positioning and stable clamping of the specimens, meeting the design requirements of the component forces, bending moment size and direction of the test section, and accurately simulating the stress state of the angle connectors during actual flight of the aircraft.

[0005] The technical solution adopted by the present invention is:

[0006] A fatigue test fixture for typical angle connectors of bulkheads includes a fixed box body, a side plate, a lever and a loading mechanism, wherein the fixed box body and the lever are vertically connected (in an L shape); the fixed box body is fixedly connected with the horizontal part of the angle connector and the side plate from bottom to top, and the side plate is fixedly connected to the horizontal part of the angle connector; the lever is provided with a groove, and the vertical part of the angle connector is fixed in the groove; the loading mechanism includes an upper loading component and a lower loading component, wherein the upper loading component is rotationally connected to the fixed box body, and the lower loading component is rotationally connected to the lever. During the loading process, the fixed box body and the lever connected to the angle connector will move with the displacement of the loading component, thereby correctly simulating the actual stress state of the angle connector.

[0007] In the present invention, the angled connector comprises a vertical portion and a horizontal portion, wherein the vertical portion is fixed inside the fixed box body, and the horizontal portion is fixed in the groove of the lever.

[0008] The upper loading assembly is connected to the fixed box body through a pin, and the lower loading assembly is connected to the lever through a pin. The pin holes of the upper loading assembly and the lower loading assembly are provided with bearings, so that the end connected to the upper loading assembly and the fixed box body rotates along the pin, and the end connected to the lower loading assembly and the lever rotates along the pin.

[0009] The horizontal part of the angle connector, the vertical part of the angle connector, the fixed box body and the lever all include side surfaces and bottom surfaces, and the side surfaces and the bottom surfaces are perpendicular.

[0010] One side of the horizontal part of the angle connector is fixedly connected to the side of the fixed box body, the other side of the horizontal part of the angle connector is fixedly connected to the side plate, and the bottom surface of the horizontal part of the angle connector is fixedly connected to the bottom surface of the fixed box body; one side of the vertical part of the angle connector is fixedly connected to the side of the lever, and the bottom surface of the vertical part of the angle connector is fixedly connected to the bottom surface of the lever;

[0011] The side plate comprises a bottom surface and a side surface, the bottom surface of the side plate is fixedly connected to the bottom surface of the fixed box body, and the side surface of the side plate is fixedly connected to the horizontal part of the angle connector. The bottom surface and the side surface of the side plate are perpendicular.

[0012] The gaps between the various parts of the present invention are adjusted by gaskets according to standards.

[0013] Preferably, the fixed connection is a row of bolted connections.

[0014] The material of the fixture is 30CrMnSiA alloy steel, which has a sufficiently high rigidity in the loading direction to ensure that the fixed parts around the test piece do not produce excessive deformation during the loading process.

[0015] The present invention also provides a method for using a fatigue test fixture for a typical angle connector of a bulkhead, comprising the following steps:

[0016] S1: Place the horizontal part of the angle connector into the fixed box body and fix it to the fixed box body;

[0017] S2 fixes the side panels to the angle connectors and fixes them in the fixed box body;

[0018] S3 fixes the vertical part of the angle connector into the lever groove;

[0019] S4 rotatably connects the upper loading assembly to the fixed box body, and rotatably connects the lower loading assembly to the lever;

[0020] S5 fixes the loading assembly to the testing machine through a hydraulic chuck;

[0021] S6 turns on the testing machine for testing.

[0022] Furthermore, in step S1, one side of the horizontal portion of the angle connector is fixedly connected to the side surface of the fixed box body.

[0023] The beneficial effects of the present invention are:

[0024] The invention discloses a fatigue test fixture for typical angle connectors of bulkheads, which has reasonable structure, compact components, convenient loading and unloading, and can reduce labor intensity. The positioning components are reasonable, belonging to complete positioning (large plane + short pin), low cost, durable, and can meet the requirements of section force and bending moment assessment during tensile and fatigue tests.

[0025] Since the loading end of the standard testing machine can only be displaced in the vertical direction, the displacement and bending moment of the loaded part of the specimen in other directions are limited. The clamp of the present invention adjusts the length and angle of the fixed box and the lever so that the force of the test section of the specimen meets the design requirements, which is completely consistent with the force state of the angle connector on the aircraft. The angle connector adopts the rectangular positioning principle. The bottom surface and two side surfaces of the horizontal part of the angle connector fit together with the surface of the fixed box, and are fixed and clamped by rows of bolts, which limits the degree of freedom of the specimen and completely fixes the angle. In addition, the angle connector is fixed to the side plate and the lever respectively with bolts. The design of the side plate can solve the assembly problems that may arise when the horizontal part of the angle connector is fixed. During the loading process, the fixed box and the lever connected to the angle connector will move with the displacement of the loading assembly, thereby correctly simulating the actual force state of the angle.

[0026] The fixing box and lever have positioning grooves and bolt holes that match the test piece, which can stably fix the angle connection test piece on the clamp body to prevent the test piece from slipping and splashing out to injure personnel and equipment, so its structural design is reasonable. The upper loading component or the lower loading component is designed with an adjustment and calibration center device to ensure coaxiality. During the test of the fixture, the breakpoint of the test piece is good, the test piece breaks within the gauge length, and the data discreteness is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is further described below in conjunction with the accompanying drawings.

[0028] Figure 1 It is a schematic diagram of an experimental device for testing fatigue performance of an angled connector using the fixture of the present invention;

[0029] Figure 2 It is a stereogram of a typical angle connection specimen;

[0030] Figure 3 It is a three-dimensional diagram of the assembly of the box body, side panels and angle connectors;

[0031] Figure 4 It is a three-dimensional view of the side panel;

[0032] Figure 5 It is a three-dimensional picture of the box;

[0033] Figure 6 It is a lever stereogram;

[0034] Figure 7 It is a stereogram of the fixed box body and the lever assembly;

[0035] Figure 8 This is a stereoscopic view of the complete set of fixtures with loading end.

[0036] Explanation of the serial numbers in the figure: 1 upper loading assembly, 2 pin, 3 bolt, 4 side plate, 5 lower loading assembly, 6 hydraulic chuck, 7 fatigue testing machine, 8 lever, 9 angle connector, 10 fixed box body. DETAILED DESCRIPTION

[0037] Example 1

[0038] like Figures 1 to 8 As shown: A fatigue test fixture for typical angle connectors of bulkheads, comprising a fixed box body 10, a side plate 4, a lever 8 and a loading mechanism, wherein the fixed box body 10 and the lever 8 are vertically connected (in an L shape); the fixed box body 10 is fixedly connected with a horizontal portion of an angle connector 9 and a side plate 4 from bottom to top, wherein the side plate 4 comprises a bottom surface and a side surface, wherein one side of the horizontal portion of the angle connector 9 is fixedly connected to the side surface of the fixed box body 10, and the other side of the horizontal portion of the angle connector 9 is fixedly connected to the side surface of the side plate 4, and the bottom surface of the side plate 4 is fixedly connected to the fixed box body 10. 0 bottom surface is fixedly connected; the lever 8 is provided with a groove, and the vertical part of the angle connector 9 is fixed in the groove; one side of the vertical part of the angle connector 9 is fixedly connected to the side surface of the lever 8; the loading mechanism comprises an upper loading component 1 and a lower loading component 5, the upper loading component 1 is connected to the fixed box body 10 through a pin 2, and the lower loading component 5 is connected to the lever 8 through a pin 2, and the pin holes of the upper loading component 1 and the lower loading component 5 are provided with lubricating bearings, so that the end of the upper loading component 1 connected to the fixed box body 10 rotates along the pin 2, and the end of the lower loading component 5 connected to the lever 8 rotates along the pin 2.

[0039] The gaps between the various parts of the present invention are adjusted by gaskets according to standards.

[0040] The fixed connection is a row of bolted connections.

[0041] A method for using a fatigue test fixture for a typical angle connector of a bulkhead comprises the following steps:

[0042] S1: Place the horizontal part of the angle connector 9 into the fixed box body 10 and fix it to the fixed box body 10 by means of a plurality of bolts;

[0043] S2 Connect the side surface of the side plate 4 to the horizontal part of the angle connector 9 through a plurality of bolts;

[0044] S3: Fix the bottom surface of the side panel 4 in the fixed box body 10 by means of a plurality of bolts;

[0045] S4: fix the vertical part of the angle connector 9 into the groove of the lever 8 by means of a plurality of bolts;

[0046] S5: connect the upper loading assembly 1 to the upper end of the fixed box body 10 through the pin 2, and connect the lower loading assembly 5 to the lower end of the lever 8 through the pin 2, so as to complete the assembly of the whole set of clamps;

[0047] S6 fixes the loading assembly (upper loading assembly, lower loading assembly) on the fatigue testing machine 7 through a hydraulic chuck;

[0048] S7 starts the fatigue testing machine 7 to conduct the test.

[0049] During the loading process, the box body 10 and the lever 8 connected to the angle connector will move with the displacement of the upper loading component 1 and the lower loading component 5. Figure 1 As shown, the actual stress state of the angle connector on the aircraft is correctly simulated. In addition, in order to improve the safety of the present invention, the edges of the fixture are all provided with rounded corners.

Claims

1. A fatigue test fixture suitable for typical angle connectors of bulkheads, characterized by: The invention comprises a fixed box body (10), a side plate (4), a lever (8) and a loading mechanism, wherein the fixed box body (10) and the lever (8) are vertically connected; the fixed box body (10) is fixedly connected with a horizontal portion of an angle connecting member (9) and the side plate (4) from bottom to top, and the side plate (4) is fixedly connected to the horizontal portion of the angle connecting member (9); the lever (8) is provided with a groove, and the vertical portion of the angle connecting member (9) is fixed in the groove; the loading mechanism comprises an upper loading component (1) and a lower loading component (5), the upper loading component (1) is rotationally connected to the fixed box body (10), and the lower loading component (5) is rotationally connected to the lever (8).

2. A fatigue test fixture suitable for typical angle connectors of bulkheads as claimed in claim 1, characterized in that: One side of the horizontal portion of the angle connecting piece (9) is fixedly connected to the side of the fixed box body (10), and the other side of the horizontal portion of the angle connecting piece (9) is fixedly connected to the side plate (4); one side of the vertical portion of the angle connecting piece (9) is fixedly connected to the side of the lever (8).

3. A fatigue test fixture suitable for typical angle connectors of bulkheads as claimed in claim 1 or 2, characterized in that: The side panel (4) comprises a bottom surface and a side surface, the bottom surface of the side panel (4) is fixedly connected to the fixed box body (10), and the side surface of the side panel (4) is fixedly connected to the horizontal portion of the angled connecting piece (9).

4. A fatigue test fixture for typical angle connectors of bulkheads as claimed in claim 1, characterized in that: The upper loading component (1) is connected to the fixed box body (10) via a pin (2), and the lower loading component (5) is connected to the lever (8) via a pin (2). The pin holes of the upper loading component (1) and the lower loading component (5) are provided with bearings.

5. A method for using the fatigue test fixture for typical angle connectors of bulkheads as claimed in claim 1, characterized in that: The steps include: S1: placing the horizontal portion of the angled connector (9) into the fixed box body (10) and fixedly connecting the horizontal portion of the angled connector (9) to the fixed box body (10); S2 fixedly connects the side plate (4) to the horizontal portion of the angled connector (9) and fixes them in the fixed box body (10); S3 fixes the vertical part of the angle connector (9) into the groove of the lever (8); S4: the upper loading assembly (1) is rotationally connected to the fixed box body (10), and the lower loading assembly (5) is rotationally connected to the lever (8); S5 fixes the upper loading assembly (1) and the lower loading assembly (5) on the testing machine through a hydraulic chuck; S6 turns on the testing machine for testing.

6. A method for using a fatigue test fixture for typical angle connectors of bulkheads as claimed in claim 5, characterized in that: In step S1, one side of the horizontal portion of the angled connector (9) is fixedly connected to the side surface of the fixed box body (10).

Images