Mechanical loading device for large-scale additive aircraft fuselage special-shaped main load-bearing component

Abstract

A kind of mechanics loading device of large-scale additive aircraft fuselage special-shaped main force component, including upper clamping fixed frame, lower clamping fixed frame, first force transmission mechanism, second force transmission mechanism, first push-pull force reversing mechanism and second push-pull force reversing mechanism;Upper clamping fixed frame is connected with single-shaft fatigue testing machine upper chuck;Lower clamping fixed frame is connected with single-shaft fatigue testing machine lower chuck;First force transmission mechanism is arranged at one end of upper clamping fixed frame, second force transmission mechanism is arranged at the other end of upper clamping fixed frame, and first and second force transmission mechanism are distributed in left and right mirror image symmetry relative to lower chuck;First push-pull force reversing mechanism is arranged on first force transmission mechanism, and second push-pull force reversing mechanism is arranged on second force transmission mechanism, and first and second push-pull force reversing mechanism are distributed in left and right mirror image symmetry relative to lower chuck;Two ends of test piece are connected with first push-pull force reversing mechanism and second push-pull force reversing mechanism respectively, and the middle part of test piece is connected with lower clamping fixed frame.

Description

Technical Field

[0001] This invention belongs to the field of mechanical testing equipment technology, and in particular relates to a mechanical loading device for a large additive aircraft fuselage irregular-shaped main load-bearing component. Background Technology

[0002] Traditional uniaxial fatigue testing machines can typically only apply uniaxial loads to specimens during mechanical testing, thus limiting the tests to simple uniaxial loading. However, in aerospace and other fields, many components are not subjected to uniaxial loads. For example, the main load-bearing components of large additive aircraft fuselages have more complex bending stress conditions, which traditional uniaxial fatigue testing machines cannot currently meet.

[0003] Therefore, at present, mechanical testing of large additive aircraft fuselage irregular main load-bearing components and other specimens can only be carried out using dedicated bending fatigue loading testing machines. However, dedicated bending fatigue loading testing machines are generally characterized by high prices and complex structures, resulting in high costs for conducting bending fatigue loading tests on large additive aircraft irregular main load-bearing components and other specimens. Cost factors have become a key constraint on the application and promotion of dedicated bending fatigue loading testing machines. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a mechanical loading device for large additive aircraft fuselage irregular-shaped main load-bearing components. This device extends the application of uniaxial fatigue testing machines to bending fatigue loading of large additive aircraft fuselage irregular-shaped main load-bearing components. Compared with existing dedicated bending fatigue loading testing machines, it features low cost and simple structure. It can complete bending fatigue loading tests on specimens such as large additive aircraft fuselage irregular-shaped main load-bearing components at a lower cost, effectively extending the applicability of uniaxial fatigue testing machines and meeting more complex load variation conditions, thereby making the test data closer to real-world operating conditions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a mechanical loading device for a large additive manufacturing aircraft fuselage irregular-shaped main load-bearing component, comprising an upper clamping and fixing frame, a lower clamping and fixing frame, a first force transmission mechanism, a second force transmission mechanism, a first push-pull force reversing mechanism, and a second push-pull force reversing mechanism; the upper clamping and fixing frame is fixedly connected to the upper chuck of a uniaxial fatigue testing machine; the lower clamping and fixing frame is fixedly connected to the lower chuck of a uniaxial fatigue testing machine; the first force transmission mechanism is disposed at one end of the upper clamping and fixing frame, and the second force transmission mechanism is disposed at the other end of the upper clamping and fixing frame, the first force transmission mechanism and the second force transmission mechanism being symmetrically distributed in a left-right mirror image relative to the lower chuck; the first push-pull force reversing mechanism is disposed on the first force transmission mechanism, and the second push-pull force reversing mechanism is disposed on the second force transmission mechanism, the first push-pull force reversing mechanism and the second push-pull force reversing mechanism being symmetrically distributed in a left-right mirror image relative to the lower chuck; both ends of the specimen are connected to the first push-pull force reversing mechanism and the second push-pull force reversing mechanism respectively, and the middle part of the specimen is connected to the lower clamping and fixing frame.

[0006] The upper clamping frame includes an upper support plate, a support upright plate, an upper clamping pin, and reinforcing ribs. The upper support plate is horizontally positioned. The upper clamping pin is vertically fixed to the middle of the upper surface of the upper support plate, and the upper clamping pin is clamped and fixedly engaged with the upper chuck of the uniaxial fatigue testing machine. The reinforcing ribs are fixedly positioned on the upper surface of the upper support plate on both sides of the upper clamping pin. The support upright plate is vertically positioned, and the upper end of the support upright plate is fixedly connected to the lower surface of the upper support plate. There are four support upright plates, which are evenly distributed at the four corners of the upper support plate.

[0007] A friction column is vertically arranged on the lower surface of the upper support plate. The friction column is used to simulate the friction force generated by the specimen under actual working conditions.

[0008] The lower clamping frame includes a lower support plate, a transition seat, a lower clamping pin, an ear plate seat, and a transition hinge shaft. The lower support plate is horizontally positioned. The transition seat is vertically fixed to the middle of the lower surface of the lower support plate. The lower clamping pin is vertically fixed to the middle of the lower surface of the transition seat, and the lower clamping pin is clamped and fixedly engaged with the lower chuck of the uniaxial fatigue testing machine. The ear plate seats are fixedly installed on the upper surface of the lower support plate, and there are four ear plate seats, with two ear plate seats arranged side by side at each end of the lower support plate. The transition hinge shaft is horizontally fixedly inserted into the four ear plate seats, and the transition ear plate on the lower surface of the middle part of the specimen is hinged to the transition hinge shaft.

[0009] The first and second force transmission mechanisms have the same structure, both including a force transmission rod, a crank wheel, a crank wheel axle, a bearing seat, and an omnidirectional moving connection assembly. One end of the force transmission rod is inserted and positioned into the adapter seat via a U-shaped groove, and a rod seat fastening screw is fixedly installed between the force transmission rod and the adapter seat. The bearing seat is fixedly installed at the bottom of the support plate. The crank wheel axle is fixedly mounted at the rotation center of the crank wheel, and both ends of the crank wheel axle are rotatably connected to the bearing seat. The other end of the force transmission rod is connected to the front surface of the crank wheel via the omnidirectional moving connection assembly.

[0010] The omnidirectional moving connection assembly includes a first slide rail, a first slider, a second slide rail, and a second slider; the first slide rail is fixedly mounted on the force transmission rod, and the first slide rail is parallel to the force transmission rod; the first slider is slidably connected to the first slide rail; the second slide rail is fixedly mounted on the front surface of the crank wheel, and the second slide rail is intersecting with the first slide rail; the second slider is slidably connected to the second slide rail, and the center of the second slider is connected to the center of the first slide rail through a slider hinge shaft, and the slider hinge shaft is parallel to the crank wheel shaft; the second slide rail and the rotation center of the crank wheel are eccentrically distributed.

[0011] The first and second push-pull force reversing mechanisms have the same structure, both including a first force-applying rod, a first transition bracket, a first locking positioning block, a first locking positioning pin, a second force-applying rod, a second transition bracket, a second locking positioning block, a second locking positioning pin, a force-applying reversing adjustment block, a force-applying reversing guide plate, an extended support frame, a specimen connecting bracket, and a follower connection assembly; the first and second force-applying rods are arranged vertically side by side, with the second force-applying rod located between the lower clamp of the uniaxial fatigue testing machine and the first force-applying rod; the bottom ends of both the first and second force-applying rods are connected to the rear surface of the crank wheel through the follower connection assembly; the first transition bracket is fixedly installed on the top of the first force-applying rod, the first locking positioning block is fixedly installed on the top of the first transition bracket, the first locking positioning pin is horizontally installed on the first locking positioning block, and a first return spring is provided between the first locking positioning pin and the first locking positioning block; the second transition bracket is fixedly installed on the top of the second force-applying rod, and the second locking positioning block is fixedly installed on the top of the second force-applying rod. At the top of the second adapter bracket, the second locking positioning pin is horizontally mounted on the second locking positioning block, and a second return spring is provided between the second locking positioning pin and the second locking positioning block; the assembly consisting of the first force-applying rod, the first adapter bracket, the first locking positioning block, and the first locking positioning pin, and the assembly consisting of the second force-applying rod, the second adapter bracket, the second locking positioning block, and the second locking positioning pin are distributed in a left-right mirror symmetrical distribution with respect to the rotation center of the crank wheel; the force-applying reversing adjustment block and the first locking positioning... A pin or a second locking and positioning pin is used for fixed connection and engagement. A force-reversing guide pin is fixedly installed on the force-reversing adjustment block. The specimen connecting bracket is fixedly connected to the specimen. The top of the extended support frame is fixedly connected to the specimen connecting bracket. The force-reversing guide plate is horizontally fixedly installed at the bottom of the extended support frame. A force-reversing guide groove is provided on the force-reversing guide plate. The force-reversing guide pin is located in the force-reversing guide groove. The force-reversing adjustment block has a degree of freedom of sliding relative to the force-reversing guide plate.

[0012] The follower connection assembly includes a third slide rail and a third slider; the third slide rail is fixedly installed on the rear surface of the crank wheel, and the third slide rail is intersected with the second slide rail; the third slider is slidably connected to the third slide rail, the third slide rail is eccentrically distributed with the rotation center of the crank wheel, and the third slide rail is located above the crank wheel axle; the bottom end of the first or second force rod is connected to the center of the third slider through a force rod hinge shaft, and the force rod hinge shaft is parallel to the crank wheel axle.

[0013] The beneficial effects of this invention are:

[0014] The mechanical loading device for the main load-bearing component of a large additive aircraft fuselage of this invention can extend the application scenario of uniaxial fatigue testing machine to bending fatigue loading of the main load-bearing component of a large additive aircraft fuselage. Compared with the existing special bending fatigue loading testing machine, it has the characteristics of low price and simple structure. It can complete the bending fatigue loading test of specimens such as the main load-bearing component of a large additive aircraft fuselage at a lower cost, effectively extending the applicable scope of uniaxial fatigue testing machine, and can meet more complex load change conditions, so that the test data is closer to the actual use conditions. Attached Figure Description

[0015] Figure 1 This is a structural schematic diagram of a mechanical loading device for a large additive aircraft fuselage irregular-shaped main load-bearing component (when used in conjunction with a uniaxial fatigue testing machine).

[0016] Figure 2 This is a structural schematic diagram of a mechanical loading device for a large additive aircraft fuselage irregular-shaped main load-bearing component according to the present invention;

[0017] Figure 3 This is a schematic diagram of the upper clamping and fixing frame of the present invention;

[0018] Figure 4 This is a schematic diagram of the lower clamping and fixing frame of the present invention;

[0019] Figure 5 This is a schematic diagram of the structure of the first / second force transmission mechanism of the present invention;

[0020] Figure 6 for Figure 5 Enlarged view of the middle section (I);

[0021] Figure 7 This is a schematic diagram of the structure of the first / second push-pull force reversing mechanism of the present invention;

[0022] Figure 8 for Figure 2 Enlarged view of Part II;

[0023] In the diagram, A—upper clamping frame, B—lower clamping frame, C—first force transmission mechanism, D—second force transmission mechanism, E—first push-pull force reversing mechanism, F—second push-pull force reversing mechanism, G—uniaxial fatigue testing machine, 1—upper chuck, 2—lower chuck, 3—specimen, 4—upper support plate, 5—support plate, 6—upper clamping pin, 7—reinforcing rib plate, 8—friction column, 9—lower support plate, 10—transfer seat, 11—lower clamping pin, 12—ear plate seat, 13—transfer hinge shaft, 14—transfer ear plate, 15—force transmission rod, 16—crank wheel, 17—crank wheel shaft, 18—bearing seat, 19—rod seat fastener. Screw, 20—First slide rail, 21—First slider, 22—Second slide rail, 23—Second slider, 24—First force-applying rod, 25—First adapter bracket, 26—First locking positioning block, 27—First locking positioning pin, 28—Second force-applying rod, 29—Second adapter bracket, 30—Second locking positioning block, 31—Second locking positioning pin, 32—Force-applying reversing adjustment block, 33—Force-applying reversing guide plate, 34—Extension support frame, 35—Specimen connecting bracket, 36—Force-applying reversing guide pin, 37—Force-applying reversing guide groove, 38—Third slide rail, 39—Third slider, 40—Force-applying rod hinge shaft. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] like Figures 1-8 As shown, a mechanical loading device for a large additive manufacturing aircraft fuselage irregular-shaped main load-bearing component includes an upper clamping and fixing frame A, a lower clamping and fixing frame B, a first force transmission mechanism C, a second force transmission mechanism D, a first push-pull force reversing mechanism E, and a second push-pull force reversing mechanism F. The upper clamping and fixing frame A is fixedly connected to the upper clamp 1 of a uniaxial fatigue testing machine G; the lower clamping and fixing frame B is fixedly connected to the lower clamp 2 of the uniaxial fatigue testing machine G; the first force transmission mechanism C is disposed at one end of the upper clamping and fixing frame A, and the second force transmission mechanism D is disposed at one end of the upper clamping and fixing frame B. At the other end of the clamping frame A, the first force transmission mechanism C and the second force transmission mechanism D are symmetrically distributed in a mirror image relative to the lower clamp 2; the first push-pull force reversing mechanism E is set on the first force transmission mechanism C, and the second push-pull force reversing mechanism F is set on the second force transmission mechanism D. The first push-pull force reversing mechanism E and the second push-pull force reversing mechanism F are symmetrically distributed in a mirror image relative to the lower clamp 2; the two ends of the specimen 3 are respectively connected to the first push-pull force reversing mechanism E and the second push-pull force reversing mechanism F, and the middle part of the specimen 3 is connected to the lower clamping frame B.

[0026] The upper clamping and fixing frame A includes an upper support plate 4, a support upright plate 5, an upper clamping pin 6, and a reinforcing rib plate 7. The upper support plate 4 is horizontally arranged. The upper clamping pin 6 is vertically fixed to the middle of the upper surface of the upper support plate 4, and the upper clamping pin 6 is clamped and fixedly engaged with the upper chuck 1 of the uniaxial fatigue testing machine G. The reinforcing rib plate 7 is fixedly arranged on the upper surface of the upper support plate 4 on both sides of the upper clamping pin 6. The support upright plate 5 is vertically arranged, and the upper end of the support upright plate 5 is fixedly connected to the lower surface of the upper support plate 4. There are four support upright plates 5, which are evenly distributed at the four corners of the upper support plate 4.

[0027] A friction column 8 is vertically arranged on the lower surface of the upper support plate 4. The friction column 8 is used to simulate the friction force generated by the specimen 3 under actual working conditions.

[0028] The lower clamping frame B includes a lower support plate 9, a transition seat 10, a lower clamping pin 11, an ear plate seat 12, and a transition hinge shaft 13. The lower support plate 9 is horizontally arranged. The transition seat 10 is vertically fixed to the middle of the lower surface of the lower support plate 9. The lower clamping pin 11 is vertically fixed to the middle of the lower surface of the transition seat 10, and the lower clamping pin 11 is clamped and fixedly engaged with the lower chuck 2 of the uniaxial fatigue testing machine G. The ear plate seat 12 is fixedly installed on the upper surface of the lower support plate 9. There are four ear plate seats 12, with two ear plate seats 12 arranged side by side at each end of the lower support plate 9. The transition hinge shaft 13 is horizontally fixedly inserted into the four ear plate seats 12, and the transition ear plate 14 on the lower surface of the middle part of the specimen 3 is hinged to the transition hinge shaft 13.

[0029] The first force transmission mechanism C and the second force transmission mechanism D have the same structure, both including a force transmission rod 15, a crank wheel 16, a crank wheel shaft 17, a bearing seat 18, and an omnidirectional moving connection assembly. One end of the force transmission rod 15 is inserted and positioned with the adapter seat 10 through a U-shaped groove, and a rod seat fastening screw 19 is fixedly installed between the force transmission rod 15 and the adapter seat 10. The bearing seat 18 is fixedly installed at the bottom of the support plate 5. The crank wheel shaft 17 is fixedly installed at the rotation center of the crank wheel 16, and both ends of the crank wheel shaft 17 are rotatably connected to the bearing seat 18. The other end of the force transmission rod 15 is connected to the front surface of the crank wheel 16 through the omnidirectional moving connection assembly.

[0030] The omnidirectional moving connection assembly includes a first slide rail 20, a first slider 21, a second slide rail 22, and a second slider 23. The first slide rail 20 is fixedly mounted on the force transmission rod 15, and the first slide rail 20 is distributed parallel to the force transmission rod 15. The first slider 21 is slidably connected to the first slide rail 20. The second slide rail 22 is fixedly mounted on the front surface of the crank wheel 16, and the second slide rail 22 is distributed intersectingly with the first slide rail 20. The second slider 23 is slidably connected to the second slide rail 22, and the center of the second slider 23 is connected to the center of the first slide rail 20 through a slider hinge shaft, and the slider hinge shaft is distributed parallel to the crank wheel shaft 17. The second slide rail 22 is eccentrically distributed with respect to the rotation center of the crank wheel 16.

[0031] The first push-pull force reversing mechanism E and the second push-pull force reversing mechanism F have the same structure, both including a first force-applying rod 24, a first transition bracket 25, a first locking positioning block 26, a first locking positioning pin 27, a second force-applying rod 28, a second transition bracket 29, a second locking positioning block 30, a second locking positioning pin 31, a force-applying reversing adjustment block 32, a force-applying reversing guide plate 33, an extended support frame 34, a specimen connecting bracket 35, and a follow-up connection assembly; the first force-applying rod 24 and the second force-applying rod 28 are arranged vertically side by side, and the second force-applying rod 28 is located between the lower clamp 2 of the uniaxial fatigue testing machine G and the first force-applying rod 28. Between the force rods 24; the bottom ends of the first force rod 24 and the second force rod 28 are both connected to the rear surface of the crank wheel 16 via a follower connection assembly; the first adapter bracket 25 is fixedly installed on the top of the first force rod 24, the first locking positioning block 26 is fixedly installed on the top of the first adapter bracket 25, the first locking positioning pin 27 is horizontally installed on the first locking positioning block 26, and a first return spring is provided between the first locking positioning pin 27 and the first locking positioning block 26; the second adapter bracket 29 is fixedly installed on the top of the second force rod 28, and the second locking positioning block 30 is fixedly installed on... At the top of the second adapter bracket 29, the second locking positioning pin 31 is horizontally mounted on the second locking positioning block 30, and a second return spring is provided between the second locking positioning pin 31 and the second locking positioning block 30; the assembly consisting of the first force-applying rod 24, the first adapter bracket 25, the first locking positioning block 26, and the first locking positioning pin 27, and the assembly consisting of the second force-applying rod 28, the second adapter bracket 29, the second locking positioning block 30, and the second locking positioning pin 31 are distributed in a left-right mirror symmetrical distribution relative to the rotation center of the crank wheel 16; the force-applying reversing adjustment block 32 and the first locking positioning... The pin 27 or the second locking and positioning pin 31 are fixedly connected and engaged. A force-reversing guide pin 36 is fixedly installed on the force-reversing adjustment block 32. The specimen connecting bracket 35 is fixedly connected and engaged with the specimen 3. The top end of the extension support frame 34 is fixedly connected to the specimen connecting bracket 35. The force-reversing guide plate 33 is horizontally fixedly installed at the bottom end of the extension support frame 34. A force-reversing guide groove 37 is provided on the force-reversing guide plate 33. The force-reversing guide pin 36 is located in the force-reversing guide groove 37. The force-reversing adjustment block 32 has a degree of freedom of sliding relative to the force-reversing guide plate 33.

[0032] The follower connection assembly includes a third slide rail 38 and a third slider 39; the third slide rail 38 is fixedly installed on the rear surface of the crank wheel 16, and the third slide rail 38 and the second slide rail 22 are distributed in a cross pattern; the third slider 39 is slidably connected to the third slide rail 38, the third slide rail 38 is eccentrically distributed with the rotation center of the crank wheel 16, and the third slide rail 38 is located above the crank wheel shaft 17; the bottom end of the first force rod 24 or the second force rod 28 is connected to the center of the third slider 39 through the force rod hinge shaft 40, and the force rod hinge shaft 40 is distributed parallel to the crank wheel shaft 17.

[0033] The following describes a single use of the present invention with reference to the accompanying drawings:

[0034] After the specimen 3 is assembled with the uniaxial fatigue testing machine G through the mechanical loading device of the present invention, the force reversing adjustment block 32 in the first push-pull force reversing mechanism E and the second push-pull force reversing mechanism F are both fixedly connected to the top of the first force applying rod 24, and the second force applying rod 28 is in an unused state.

[0035] During the loading test, the lower clamp 2 of the uniaxial fatigue testing machine G outputs a uniaxial load. This uniaxial load is applied to the middle of the specimen 3 in sequence through the lower clamping pin 11, the adapter seat 10, the lower support plate 9, the ear plate seat 12, and the adapter hinge 13. At the same time, the uniaxial load is also applied to the two crank wheels 16 in sequence through the lower clamping pin 11, the adapter seat 10, the force transmission rod 15, and the omnidirectional moving connection assembly. This causes the crank wheels 16 to swing around their rotation center. At this time, the swinging motion of the crank wheels 16 is converted into the thrust load of the first force application rod 24 through the follower connection assembly. This thrust load is applied to both ends of the specimen 3 in sequence through the force reversing adjustment block 32, the force reversing guide plate 33, the extended support frame 34, and the specimen connecting angle frame 35. Finally, the uniaxial load output by the lower clamp 2 is converted into the thrust load at both ends of the specimen 3, thereby realizing the bending fatigue loading test with thrust at both ends.

[0036] Similarly, when the force reversing adjustment block 32 in the first push-pull force reversing mechanism E and the second push-pull force reversing mechanism F are both fixedly connected to the top of the second force rod 28, the first force rod 24 is in an unused state. The swing motion of the crank wheel 16 will be converted into the tensile load of the second force rod 28 through the follower connection assembly. This tensile load will also be applied to both ends of the specimen 3 in sequence through the force reversing adjustment block 32, the force reversing guide plate 33, the extended support frame 34 and the specimen connecting angle frame 35. Finally, the uniaxial load output by the lower clamp 2 will be converted into the tensile load at both ends of the specimen 3, thereby realizing the bending fatigue loading test of the tensile force at both ends.

[0037] Furthermore, when the force reversing adjustment block 32 in the first push-pull force reversing mechanism E is fixedly connected to the top of the first force-applying rod 24, and the force reversing adjustment block 32 in the second push-pull force reversing mechanism F is fixedly connected to the top of the second force-applying rod 28, or when the force reversing adjustment block 32 in the first push-pull force reversing mechanism E is fixedly connected to the top of the second force-applying rod 28, and the force reversing adjustment block 32 in the second push-pull force reversing mechanism F is fixedly connected to the first force-applying rod 24, the oscillation of one side crank wheel 16... The force is converted into a thrust load of the first force bar 24 through the follower connection assembly, which acts on one end of the specimen 3; at the same time, the swing motion of the crank wheel 16 on the other side is converted into a tensile load of the second force bar 28 through the follower connection assembly, which acts on the other end of the specimen 3. Finally, the uniaxial load output by the lower clamp 2 is converted to both ends of the specimen 3, forming a complex stress state with a thrust load on one end and a tensile load on the other end, thereby realizing the bending fatigue loading test under complex stress state.

[0038] The solutions in the embodiments are not intended to limit the scope of protection of the present invention. All equivalent implementations or modifications that do not depart from the present invention are included in the scope of protection of the present invention.

Claims

1. A mechanical loading device for a large additive manufacturing aircraft fuselage irregular-shaped main load-bearing component, characterized in that: The device includes an upper clamping and fixing frame, a lower clamping and fixing frame, a first force transmission mechanism, a second force transmission mechanism, a first push-pull force reversing mechanism, and a second push-pull force reversing mechanism. The upper clamping and fixing frame is fixedly connected to the upper chuck of the uniaxial fatigue testing machine. The lower clamping and fixing frame is fixedly connected to the lower chuck of the uniaxial fatigue testing machine. The first force transmission mechanism is located at one end of the upper clamping and fixing frame, and the second force transmission mechanism is located at the other end of the upper clamping and fixing frame. The first and second force transmission mechanisms are symmetrically distributed in a mirror image relative to the lower chuck. The first push-pull force reversing mechanism is located on the first force transmission mechanism, and the second push-pull force reversing mechanism is located on the second force transmission mechanism. The first and second push-pull force reversing mechanisms are symmetrically distributed in a mirror image relative to the lower chuck. The two ends of the specimen are connected to the first and second push-pull force reversing mechanisms, respectively, and the middle part of the specimen is connected to the lower clamping and fixing frame. The lower clamping frame includes a lower support plate, a transition seat, a lower clamping pin, an ear plate seat, and a transition hinge shaft. The lower support plate is horizontally positioned. The transition seat is vertically fixed to the middle of the lower surface of the lower support plate. The lower clamping pin is vertically fixed to the middle of the lower surface of the transition seat, and the lower clamping pin is clamped and fixedly engaged with the lower chuck of the uniaxial fatigue testing machine. The ear plate seats are fixedly installed on the upper surface of the lower support plate, and there are four ear plate seats, with two ear plate seats arranged side by side at each end of the lower support plate. The transition hinge shaft is horizontally fixedly inserted into the four ear plate seats, and the transition ear plate on the lower surface of the middle part of the specimen is hinged to the transition hinge shaft. The first and second force transmission mechanisms have the same structure, both including a force transmission rod, a crank wheel, a crank wheel axle, a bearing seat, and an omnidirectional moving connection assembly. One end of the force transmission rod is inserted and positioned into the adapter seat via a U-shaped groove, and a rod seat fastening screw is fixedly installed between the force transmission rod and the adapter seat. The bearing seat is fixedly installed at the bottom of the support plate. The crank wheel axle is fixedly mounted at the rotation center of the crank wheel, and both ends of the crank wheel axle are rotatably connected to the bearing seat. The other end of the force transmission rod is connected to the front surface of the crank wheel via the omnidirectional moving connection assembly.

2. The mechanical loading device for a large additive aircraft fuselage irregular-shaped main load-bearing component according to claim 1, characterized in that: The upper clamping frame includes an upper support plate, a support upright plate, an upper clamping pin, and reinforcing ribs. The upper support plate is horizontally positioned. The upper clamping pin is vertically fixed to the middle of the upper surface of the upper support plate, and the upper clamping pin is clamped and fixedly engaged with the upper chuck of the uniaxial fatigue testing machine. The reinforcing ribs are fixedly positioned on the upper surface of the upper support plate on both sides of the upper clamping pin. The support upright plate is vertically positioned, and the upper end of the support upright plate is fixedly connected to the lower surface of the upper support plate. There are four support upright plates, which are evenly distributed at the four corners of the upper support plate.

3. The mechanical loading device for a large additive aircraft fuselage irregular-shaped main load-bearing component according to claim 2, characterized in that: A friction column is vertically arranged on the lower surface of the upper support plate. The friction column is used to simulate the friction force generated by the specimen under actual working conditions.

4. The mechanical loading device for a large additive aircraft fuselage irregular-shaped main load-bearing component according to claim 1, characterized in that: The omnidirectional moving connection assembly includes a first slide rail, a first slider, a second slide rail, and a second slider; the first slide rail is fixedly mounted on the force transmission rod, and the first slide rail is parallel to the force transmission rod; the first slider is slidably connected to the first slide rail; the second slide rail is fixedly mounted on the front surface of the crank wheel, and the second slide rail is intersecting with the first slide rail; the second slider is slidably connected to the second slide rail, and the center of the second slider is connected to the center of the first slide rail through a slider hinge shaft, and the slider hinge shaft is parallel to the crank wheel shaft; the second slide rail and the rotation center of the crank wheel are eccentrically distributed.

5. The mechanical loading device for a large additive aircraft fuselage irregular-shaped main load-bearing component according to claim 1, characterized in that: The first and second push-pull force reversing mechanisms have the same structure, both including a first force-applying rod, a first transition bracket, a first locking positioning block, a first locking positioning pin, a second force-applying rod, a second transition bracket, a second locking positioning block, a second locking positioning pin, a force-applying reversing adjustment block, a force-applying reversing guide plate, an extended support frame, a specimen connecting bracket, and a follower connection assembly; the first and second force-applying rods are arranged vertically side by side, with the second force-applying rod located between the lower clamp of the uniaxial fatigue testing machine and the first force-applying rod; the bottom ends of both the first and second force-applying rods are connected to the rear surface of the crank wheel through the follower connection assembly; the first transition bracket is fixedly installed on the top of the first force-applying rod, the first locking positioning block is fixedly installed on the top of the first transition bracket, the first locking positioning pin is horizontally installed on the first locking positioning block, and a first return spring is provided between the first locking positioning pin and the first locking positioning block; the second transition bracket is fixedly installed on the top of the second force-applying rod, and the second locking positioning block is fixedly installed on the top of the second force-applying rod. At the top of the second adapter bracket, the second locking positioning pin is horizontally mounted on the second locking positioning block, and a second return spring is provided between the second locking positioning pin and the second locking positioning block; the assembly consisting of the first force-applying rod, the first adapter bracket, the first locking positioning block, and the first locking positioning pin, and the assembly consisting of the second force-applying rod, the second adapter bracket, the second locking positioning block, and the second locking positioning pin are distributed in a left-right mirror symmetrical distribution with respect to the rotation center of the crank wheel; the force-applying reversing adjustment block and the first locking positioning... A pin or a second locking and positioning pin is used for fixed connection and engagement. A force-reversing guide pin is fixedly installed on the force-reversing adjustment block. The specimen connecting bracket is fixedly connected to the specimen. The top of the extended support frame is fixedly connected to the specimen connecting bracket. The force-reversing guide plate is horizontally fixedly installed at the bottom of the extended support frame. A force-reversing guide groove is provided on the force-reversing guide plate. The force-reversing guide pin is located in the force-reversing guide groove. The force-reversing adjustment block has a degree of freedom of sliding relative to the force-reversing guide plate.

6. The mechanical loading device for a large additive aircraft fuselage irregular-shaped main load-bearing component according to claim 5, characterized in that: The follower connection assembly includes a third slide rail and a third slider; the third slide rail is fixedly installed on the rear surface of the crank wheel, and the third slide rail is intersected with the second slide rail; the third slider is slidably connected to the third slide rail, the third slide rail is eccentrically distributed with the rotation center of the crank wheel, and the third slide rail is located above the crank wheel axle; the bottom end of the first or second force rod is connected to the center of the third slider through a force rod hinge shaft, and the force rod hinge shaft is parallel to the crank wheel axle.

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