Double-lug double-shaft tension-torsion fatigue test loading device
By designing a biaxial tensile-torsional fatigue test loading device with double lugs, the problem of fatigue characteristic evaluation of double lug structures under biaxial loads was solved, reliable design data was provided, and high-precision fatigue performance evaluation and failure mode analysis were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINA HELICOPTER RES & DEV INST
- Filing Date
- 2025-04-03
- Publication Date
- 2026-04-24
AI Technical Summary
Existing technologies are insufficient to effectively assess the fatigue characteristics and failure modes of double-eared structures under the coupled effects of axial tensile and compressive loads and rotational loads around the bolt hole axis, resulting in a lack of reliable data support for fatigue strength design.
A dual-ear biaxial tensile-torsional fatigue test loading device was designed. Axial tensile and compressive loads are applied by an actuator, and rotational loads around the bolt hole axis are achieved by a lateral loading adapter plate and a spherical bearing. Combined with displacement and angle sensors for monitoring, the fatigue performance of the dual-ear plates under biaxial loads is simulated.
It enables accurate evaluation of the fatigue performance and failure mode of the double-ear structure under biaxial tensile and torsional loads, provides reliable design data support, and the device has a simple structure, low cost, high stability of loading waveform, and an error of less than 3%.
Smart Images
Figure CN224163508U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of helicopter fatigue testing technology, and specifically relates to a dual-ear dual-axis tensile-torsional fatigue testing loading device. Background Technology
[0002] The double-lug structure is a common connection type, widely used in the connection design of helicopter structural components, such as the connection between the helicopter's dynamic ring boom and the tie rod. For fatigue performance evaluation of double-lug structures, a method of applying tensile and compressive loads along the tie rod's axial direction is often used. However, as the helicopter's flight load changes, the double-lug structure deforms. The actual load transmitted from the tie rod to the double-lug structure, in addition to the axial tensile and compressive loads, also generates a periodic rotational load around the double-lug bolt holes. This means that the double-lug structure ultimately experiences a coupled force of axial tensile and compressive loads and a rotational load around the double-lug bolt hole axis. To better assess the fatigue characteristics and weak points of the double-lug structure under this coupled force, and to guide the design of the double-lug structure's fatigue strength, biaxial tensile-torsional fatigue tests are necessary. Utility Model Content
[0003] Purpose of this utility model: For biaxial tensile-torsional fatigue testing technology of double-eared structures subjected to axial tensile and compressive loads and rotational loads around the bolt hole axis of the double-eared structure, this utility model provides a loading device for biaxial tensile-torsional fatigue testing of double-eared structures. The device has a simple structure and can apply tensile and compressive loads to the double-eared structure in the vertical direction, while simultaneously applying rotational loads to the double-eared structure from the side. This allows for the acquisition of fatigue performance and failure modes of the double-eared structure under the coupled action of biaxial tensile and torsional loads, providing reliable data support for guiding the design of fatigue strength of double-eared structures.
[0004] Technical solution
[0005] A dual-ear biaxial tensile-torsional fatigue testing loading device includes: an actuator, a connecting assembly, a fixed loading frame, a torsion frame, and a vertical loading fork.
[0006] The frame has a groove in the middle and an ear piece at each end, with the plane of the ear piece perpendicular to the plane of the groove.
[0007] The single plate below the double ear pieces is inserted into the groove of the torsion frame, and the double ears above the double ear pieces are hinged to the vertical loading fork ears through a joint bearing.
[0008] Each of the two lugs above the torsion frame has a torsion rolling bearing embedded in it, and the torsion pin passes through the torsion rolling bearing and is connected to the fixed loading frame.
[0009] The actuator is connected to the torsion frame via an adapter assembly.
[0010] Furthermore, the adapter assembly includes: an actuator loading fork lug, a lateral loading adapter plate, and a lateral loading fork lug;
[0011] The lateral loading adapter plate is H-shaped, with one end connected to the actuator output shaft via an actuator loading fork, and the other end connected to the torsion frame via a lateral loading fork.
[0012] Furthermore, the single plate below the double ear pieces has two through holes, and the single plate below the double ear pieces is connected to the torsion frame by bolts.
[0013] Furthermore, the actuator is mounted on the ground via an actuator mounting base, thereby restricting the actuator's movement in the horizontal direction.
[0014] Furthermore, the device also includes a displacement sensor mounted on the actuator output shaft.
[0015] Furthermore, an angle sensor is provided on the side of the torsion frame to measure the rotation angle of the torsion frame.
[0016] In summary, the beneficial effects of this utility model are as follows:
[0017] This invention features a simple structure and lower manufacturing cost compared to biaxial tensile-torsion testing machines. It also provides stable loading waveforms with an error not exceeding 3%. Using this invention, axial tensile and compressive loads can be applied to the dual lugs while simultaneously driving them to rotate around their bolt hole axes, thus obtaining the fatigue performance and failure modes of the dual lugs under biaxial tensile-torsion load coupling. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of a typical double-eared test piece involved in this utility model;
[0019] Figure 2 This is a schematic diagram of the overall structure of the device of this utility model;
[0020] Figure 3 This is a sectional view parallel to the axial direction of the two ear pieces;
[0021] Figure 4 This is a cross-sectional view of the connecting bolts. Detailed Implementation
[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0023] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.
[0024] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.
[0025] This utility model relates to a loading device for a biaxial tensile-torsional fatigue test with two lugs, comprising an actuator 1, an actuator mounting base 2, a displacement sensor 3, an actuator loading fork lug 4, a lateral loading adapter plate 5, a lateral loading fork lug 6, a fixed loading frame 7, a torsion frame 8, a vertical loading fork lug 9, an angle sensor 10, a pin fixing bolt 11, a torsion pin 12, a torsion rolling bearing 13, a spherical bearing 14, a biaxial lug test piece 15, and a connecting bolt 16.
[0026] The double-ear test piece 15 is a test piece with a double-fork ear structure at one end, which is connected to the vertical loading fork ear 9 through a spherical bearing 14 and a connecting bolt 16 to simulate the connection loading form between the tie rod and the dynamic ring arm in the helicopter structure. The other end of the double-ear test piece 15 is a single plate structure containing two through holes. During the test installation, this single plate structure is embedded in the groove of the torsion frame 8 and fixedly connected with two connecting bolts 16. Thus, the torsion frame 8 drives the double-ear test piece 15 to rotate around its double-ear axis, simulating the state of stress deformation and relative rotation of the tie rod during the use of the helicopter dynamic ring arm.
[0027] The actuator mounting base 2 is horizontally fixed, and the actuator 1 is horizontally fixed on the actuator mounting base 2, restricting the actuator 1 to transmit load only in the horizontal direction. The displacement sensor 3 installed on the actuator 1 is used to control the extension and retraction length of the actuator 1, thereby driving the lateral loading adapter plate 5 to move in a displacement control manner. The left and right ends of the lateral loading adapter plate 5 are connected to the actuator loading fork lug 4 and the lateral loading fork lug 6 respectively by bolts 16. Both ends of the lateral loading adapter plate 5 are connected to the spherical bearings 14, so the lateral loading adapter plate 5 can rotate together with the lateral loading fork lug 6 while the actuator loading fork lug 4 moves translationally.
[0028] The lateral loading fork 6 is fixedly connected to the torsion frame 8 by means of threads, and transmits the load transmitted by the horizontally mounted actuator 1.
[0029] Each of the two lugs of the torsion frame 8 has a torsion rolling bearing 13 embedded in it. The two lugs of the torsion frame 8 are respectively installed in the slots on both sides of the loading frame 7 via torsion pins 12, and the torsion pins 12 are fixed with pin fixing bolts 11, so that the torsion frame 8 can rotate around the axis of its lug hole. A slot with the same width as the double lug test piece 15 is designed at the bottom of the torsion frame 8. The double lug test piece 15 is embedded in the slot at the bottom of the torsion frame 8 and connected together by two side-mounted bolts, so that the torsion frame 8 and the double lug test piece 15 rotate together around the axis of the lug bolt hole of the double lug test piece 15.
[0030] Vertical load is applied by the vertical loading fork 9, and the fixed loading frame 7 is fixed on the test platform, so that both the vertical load and the lateral load are ultimately transferred to the fixed loading frame 7.
[0031] Angle sensor 10 is installed on the lug of torsion frame 8. Before the test, the displacement corresponding to displacement sensor 3 is calibrated by measuring the rotation angle of torsion frame 8 (e.g., ±5°) to determine the extension and retraction displacement of actuator 1 during the formal test, thereby achieving the loading requirements of rotation angle of torsion frame 8.
[0032] Test methods
[0033] Step 1: Set up the test device and design the structural form of both ends of the double-ear test piece 15. One end is a double-fork ear structure to simulate the connection between the helicopter tie rod and the dynamic ring arm. The other end is a single plate structure to facilitate the application of torsion, which is used to simulate the stress deformation of the helicopter dynamic ring arm during use and the relative rotation of the tie rod.
[0034] Step 2: Determine the test load. Apply the specified tie rod load vertically to the double-ear test piece 15 using the vertical loading fork 9. The rotational load limit is the relative rotation angle between the helicopter structure and the tie rod axis after the structure is deformed under load.
[0035] Step 3: Execute the loading and monitor the loading process. During the test, continuously monitor the load on the vertical tie rod, the displacement value of displacement sensor 3, and the angle sensor 10. The displacement value of displacement sensor 3 is the displacement amount converted from the calibrated angle of angle sensor 10. During test monitoring, the displacement value of displacement sensor 3 and the angle value of angle sensor 10 can be compared to verify the accuracy of the loading. If the load is found to deviate from the preset error value (generally a 3% error limit), the test should be suspended, the cause should be identified and the fault eliminated before the test can continue, to ensure that the data throughout the test process are true and accurate.
[0036] Step 4: Determine the test termination condition. The test is considered complete when a visually visible crack appears on the double-eared test piece 15.
[0037] Step 5: Calculate the fatigue life of the double-eared test piece 15 based on the total number of fatigue loading cycles in the test.
[0038] Example
[0039] The axial load of the double-eared test piece 15 along Figure 1 In the X-axis direction, the rotation angle load is around Figure 1 The Y-axis direction, that is, the axis of the double-ear bolt hole.
[0040] This utility model relates to a loading device for a biaxial tensile-torsional fatigue test with two lugs, characterized in that it includes an actuator 1, an actuator fixing seat 2, a displacement sensor 3, an actuator loading fork lug 4, a lateral loading adapter plate 5, a lateral loading fork lug 6, a fixed loading frame 7, a torsion frame 8, a vertical loading fork lug 9, an angle sensor 10, a pin fixing bolt 11, a torsion pin 12, a torsion rolling bearing 13, a spherical bearing 14, a biaxial lug test piece 15, and a connecting bolt 16.
[0041] A lateral loading device consists of actuator 1, actuator mounting base 2, displacement sensor 3, actuator loading fork lug 4, lateral loading adapter plate 5, lateral loading fork lug 6, torsion frame 8, angle sensor 10, and connecting bolt 16. The displacement sensor 3 controls the actuator 1 to load in the horizontal direction through displacement loading command, which pushes the lateral loading adapter plate 5 to move. The lateral loading adapter plate 5 then drives the torsion frame 8 and the double-ear test piece 15 to rotate together around the axis of the double-ear bolt hole. During the entire lateral loading process, the lateral loading adapter plate 5 can rotate with the rotation of the torsion frame 8 while translating, thus avoiding interference.
[0042] Angle sensor 10 is installed on torsion frame 8. Before the test, the displacement corresponding to displacement sensor 3 is calibrated by measuring the rotation angle of torsion frame 8 (e.g., ±5°). This determines the extension and retraction displacement of actuator 1 during the formal test, thus achieving the loading requirements for the rotation angle of torsion frame 8. During the test, the change of test loading angle can be monitored in real time, and the test angle loading data can be accurately recorded.
[0043] Each of the two lugs of the torsion frame 8 has a torsion rolling bearing 13 embedded in it. The two lugs of the torsion frame 8 are respectively installed in the slots on both sides of the loading frame 7 via torsion pins 12, and the torsion pins 12 are fixed with pin fixing bolts 11, so that the torsion frame 8 can rotate around the axis of its lug hole. A slot with the same width as the double lug test piece 15 is designed at the bottom of the torsion frame 8. The double lug test piece 15 is embedded in the slot at the bottom of the torsion frame 8 and connected together by two side-mounted bolts, so that the torsion frame 8 and the double lug test piece 15 rotate together around the axis of the lug bolt hole of the double lug test piece 15.
[0044] The vertical loading fork 9 has an embedded spherical bearing 14, which is connected to the double lugs of the double lug test piece 15 via connecting bolts 16, simulating the typical connection between the double lugs and the tie rod on a helicopter. The vertical loading fork 9 applies a vertical load, and the fixed loading frame 7 is fixed on the test platform, so that both the vertical load and the lateral load are ultimately transferred to the fixed loading frame 7.
[0045] Using this device, the stress state of the double-ear structure of a helicopter can be accurately simulated, and the fatigue performance and failure mode of the double-ear structure under biaxial tensile and torsional fatigue test loads can be evaluated. During the test, the axial tensile and compressive loads and rotation angles can be accurately monitored.
[0046] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A dual-ear biaxial tensile-torsional fatigue testing loading device, characterized in that: include: Actuator, adapter assembly, fixed loading frame, torsion frame, vertical loading fork; The frame has a groove in the middle and an ear piece at each end, with the plane of the ear piece perpendicular to the plane of the groove. The single plate below the double ear pieces is inserted into the groove of the torsion frame, and the double ears above the double ear pieces are hinged to the vertical loading fork ears through a joint bearing. Each of the two lugs above the torsion frame has a torsion rolling bearing embedded in it, and the torsion pin passes through the torsion rolling bearing and is connected to the fixed loading frame. The actuator is connected to the torsion frame via an adapter assembly.
2. The apparatus according to claim 1, characterized in that: The adapter assembly includes: actuator loading fork lug, lateral loading adapter plate, and lateral loading fork lug; The lateral loading adapter plate is H-shaped, with one end connected to the actuator output shaft via an actuator loading fork, and the other end connected to the torsion frame via a lateral loading fork.
3. The apparatus according to claim 2, characterized in that: The single plate below the double ear pieces has two through holes, and the single plate below the double ear pieces is connected to the torsion frame by bolts.
4. The apparatus according to claim 3, characterized in that: The actuator is mounted on the ground via an actuator mounting base, which restricts the actuator's horizontal movement.
5. The apparatus according to claim 4, characterized in that: The device also includes a displacement sensor mounted on the actuator output shaft.
6. The apparatus according to claim 5, characterized in that: An angle sensor is installed on the plate of the torsion frame to measure the rotation angle of the torsion frame.