A device for testing the strength of an aircraft fuselage panel

Abstract

The application discloses an aircraft fuselage wallboard strength test device, and belongs to the technical field of aircraft wallboard testing, which comprises a detection table, a fixed backboard, a boundary clamp, a wallboard test piece and a load test assembly. The boundary clamp is self-adaptive clamped by a flexible clamping plate driven by a hydraulic pressure. The flexible clamping plate is filled with a current variable liquid. The clamping force can be accurately adjusted by cooperating with an electric field generator, the actual connection strength is simulated, the load test assembly applies static load through a hydraulic rod, the electromagnetic coil of the load transmission rod drives the detection rod to reciprocatingly stretch and shrink, dynamic vibration load is applied, and the monitoring function is simultaneously achieved. The acoustic wave loader generates high-frequency acoustic waves through a piezoelectric ceramic stack, acoustic wave fatigue testing is realized, static, dynamic and acoustic wave multi-field coupling loading can be realized, ultrasonic defect detection is combined, actual working conditions are accurately simulated, the mechanical response and stability of the wallboard are comprehensively evaluated, the testing accuracy and reliability are greatly improved, and strong support is provided for the research and development of aviation wallboards.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aircraft panel testing, more particularly, to an aircraft fuselage panel strength test device. BACKGROUND

[0002] As the core load-bearing component of an aircraft, the aircraft fuselage panel directly bears the complex mechanical actions such as aerodynamic load, structural vibration, and engine sound wave fatigue during flight, and its structural strength and stability are directly related to flight safety. With the development of the aviation industry towards high load, long life, and light weight, the reliability requirements for the aircraft fuselage panel are increasingly improved, and therefore, it is necessary to simulate the stress environment under actual working conditions through a precise strength test device to comprehensively evaluate the mechanical response and structural safety of the panel.

[0003] At present, the existing aircraft fuselage panel strength test device has many deficiencies and cannot meet the needs of precise testing. In terms of boundary clamping, the traditional device mostly uses rigid clamps, and the clamping size is fixed, which has poor adaptability and cannot meet the testing needs of panel test pieces of different specifications and shapes. Moreover, the clamping force cannot be adjusted, it is difficult to simulate the connection strength of the panel and the fuselage under actual working conditions, and rigid clamping can also easily cause damage to the edges of the test piece, affecting the accuracy of the test results. Some improved devices use hydraulic drive clamping, but lack self-adaptive adjustment capability. When the panel test piece is placed off-center or the size has deviations, uniform clamping cannot be achieved, resulting in a large difference between the boundary constraint conditions and the actual working conditions.

[0004] In terms of load application, the existing device mostly uses single static load or simple dynamic load, and cannot realize the coordinated application of vibration load and sound wave load. However, in actual flight, the aircraft panel often simultaneously bears the coupling action of vibration and sound waves, and single load testing cannot fully reflect the real mechanical properties of the panel. At the same time, the monitoring accuracy of the dynamic load is insufficient, the contact state between the test piece and the loading mechanism cannot be accurately obtained, and it is difficult to identify critical working conditions such as contact instability, resulting in insufficient completeness of the test data. SUMMARY

[0005] 1. Technical problem to be solved

[0006] In view of the problems in the prior art, the purpose of the present application is to provide an aircraft fuselage panel strength test device, which can realize static, dynamic, and sound wave multi-field coupled loading, combined with ultrasonic defect detection, accurately simulate actual working conditions, comprehensively evaluate the mechanical response and stability of the panel, greatly improve the testing accuracy and reliability, and provide strong support for the research and development of aircraft panels.

[0007] 2. Technical scheme

[0008] To solve the above problems, the present application adopts the following technical scheme.

[0009] An aircraft fuselage wallboard strength test device, including a detection table, the upper end of the detection table is fixedly installed with a boundary clamp, the boundary clamp clamps a wallboard test piece, the rear end of the detection table is fixedly installed with a fixed back plate, the lower end of the fixed back plate is fixedly installed with a load test assembly, and the load test assembly is located above the wallboard test piece;

[0010] The load test assembly comprises an arc top plate fixedly installed at the lower end of the fixed back plate, a plurality of annular array distributed hydraulic rods are fixedly installed at the lower end of the arc top plate, a connecting table is fixedly installed at the output end of the hydraulic rods, a load transmission rod is fixedly installed at one end of the connecting table close to the wallboard test piece, and a matching load curved surface transmission plate is fixedly installed at one end of the load transmission rod close to the wallboard test piece.

[0011] As a further improvement of the present application, the boundary clamp comprises a mounting bottom plate, side slots are formed at the left and right ends of the mounting bottom plate, a pair of symmetrically distributed flexible clamping plates are slidably installed in the side slots, a pair of guide slides corresponding to the side slots are fixedly installed at the front end of the mounting bottom plate, the wallboard test piece can be guided into the side slots through the guide slides, and then the wallboard test piece is adjustably clamped and fixed by the pair of flexible clamping plates, so as to adapt to wallboard test pieces of different sizes and types.

[0012] As a further improvement of the present application, a pair of U-shaped flow channels corresponding to the side slots are formed in the mounting bottom plate, a hydraulic oil pump is connected to the U-shaped flow channels through a hydraulic oil pipe, interference fit hydraulic pistons are slidably installed at the left and right openings of the U-shaped flow channels, and a synchronous rod is fixedly installed between the hydraulic pistons and the flexible clamping plates. The hydraulic oil is injected into the U-shaped flow channels through the hydraulic oil pump through the hydraulic oil pipe, the hydraulic pistons are extruded and moved outward by hydraulic action, and then the flexible clamping plates are pushed to contact and abut against the wallboard test piece through the synchronous rod, so that the wallboard test piece is well clamped. It can adapt to wallboard test pieces of different sizes and positions with deviations, for example, the wallboard test piece is not centered before testing or the size is larger, and the outer surface of the edge is closer to the outside of the flexible clamping plate. Therefore, under the action of hydraulic pressure, the flexible clamping plate on the outside will quickly come into contact and then cannot continue to move. At this time, the hydraulic action is actively applied to the flexible clamping plate on the inside, so that it continues to move until it contacts the wallboard test piece. Finally, the pair of flexible clamping plates can achieve uniform clamping of the wallboard test piece at both sides of the boundary. The flexible clamping plate can clasp the wallboard test piece by utilizing its flexible fitting characteristics.

[0013] As a further improvement of the present application, the flexible clamping plate is a hollow elastic capsule structure and is filled with electrorheological fluid inside, and is electrically connected with an electric field generator. Different clamping forces are realized by applying electric fields of different intensities, so as to simulate the connection strength of the aircraft wallboard under actual working conditions and improve the boundary simulation effect.

[0014] As a further improvement of the present application, the load transmission rod comprises a hollow sleeve, a matched detection rod is slidingly installed inside the hollow sleeve, a through hole matched with the detection rod is formed in the lower end of the load curved surface transmission plate, the detection rod extends out of the load curved surface transmission plate and reciprocates at a specific frequency to simulate the vibration environment in actual flight to apply dynamic load.

[0015] As a further improvement of the present application, a magnetic guide rod is fixedly installed at the upper end of the detection rod, an electromagnetic coil corresponding to the magnetic guide rod is fixedly installed inside the hollow sleeve, a connecting plate is fixedly installed at the upper end of the magnetic guide rod, a tension spring is fixedly installed between the connecting plate and the top wall of the hollow sleeve, a changeable magnetic field is generated by controlling the electromagnetic coil to apply an attractive-repulsive driving force to the magnetic guide rod to drive the detection rod to extend out of the load curved surface transmission plate and reciprocate at a specific frequency to simulate the vibration environment in actual flight to apply dynamic load to the wall plate test piece, meanwhile, the electromagnetic coil can also be used as a sensing coil, according to Faraday's law of electromagnetic induction, when the magnetic guide rod moves relative to the coil, a voltage will be induced in the coil, the amplitude of the induced voltage is proportional to the movement speed of the movable rod, by integrating the induced signal, the dynamic displacement amplitude of the detection rod and the real-time state of the contact between the detection rod and the wall plate test piece can be accurately calculated, the reference waveform of the induced signal during dynamic excitation is recorded, once the induced signal is monitored to have a sharp jump or high-frequency burr, which is a typical feature of the instantaneous separation-collision between the detection rod and the wall plate test piece, the logic immediately judges that the contact is unstable.

[0016] As a further improvement of the present application, a sound emitting groove is formed in the lower end of the detection rod, and a sound wave loader is installed in the sound emitting groove to simulate the sound wave fatigue test during the flight of the aircraft, realize multi-field coupled loading, and further comprehensively evaluate the mechanical response and stability of the connecting structure under complex working conditions.

[0017] As a further improvement of the present application, the sound wave loader comprises a piezoelectric ceramic stack, a damping backing is fixedly installed between the top wall of the sound emitting groove and the upper end of the piezoelectric ceramic stack, and a sound wave guide is fixedly installed at the lower end of the piezoelectric ceramic stack, high-frequency sound wave excitation generated by the piezoelectric ceramic stack is conducted to the wall plate test piece through the sound wave guide, the damping backing can prevent the sound wave from propagating backward to cause signal reception interference, at the moment when detection is required, dynamic loading is paused or the piezoelectric ceramic stack is used during the interval, an ultrasonic instrument emits a high-voltage electric pulse to the piezoelectric ceramic stack, the piezoelectric ceramic stack generates high-frequency vibration, which is focused and conducted to the wall plate test piece through the sound wave guide, when the sound wave propagates in the wall plate test piece, it will be reflected when encountering defects or boundaries, the echo is collected by the same sound wave guide and transmitted back to the piezoelectric ceramic stack, the piezoelectric ceramic stack converts the mechanical vibration back to an electric signal which is received and analyzed by the ultrasonic instrument.

[0018] As a further improvement of the present application, the lower end of the probe rod is fixedly installed with a matching coupling agent releasing ring, and the acoustic wave guide extends to the bottom surface of the coupling agent releasing ring, so that the coupling agent releasing ring can actively release the coupling agent during the test, which can prevent the wallboard test piece from being worn during the test, and the formed oil film can effectively conduct the excitation sound wave generated by the sound wave loader.

[0019] As a further improvement of the present application, the coupling agent releasing ring comprises an oil storage ring, the lower end of the oil storage ring is sequentially installed with a microporous sintered metal filter screen, a porous polymer releasing layer and a flexible lip-shaped sealing ring, and the upper end of the oil storage ring is installed with a sealing cover, so that when the static load is applied, the flexible lip-shaped sealing ring is pressed after contacting the wallboard test piece, a gap is formed between the flexible lip-shaped sealing ring and the probe rod, and the porous polymer releasing layer is prompted to slowly release the coupling agent and form an oil film on the surface of the wallboard test piece through the internal pressure.

[0020] 3. Beneficial effects

[0021] Compared with the prior art, the present application has the following advantages:

[0022] (1) The present application realizes self-adaptive adjustment through the flexible clamping plate driven by hydraulic pressure, can adapt to wallboard test pieces of different sizes and different placement positions, solves the poor adaptability problem of traditional rigid clamps, and ensures uniform clamping force on both sides through the hydraulic drive mode, avoiding test errors caused by uneven clamping. At the same time, the electrorheological fluid in the flexible clamping plate can accurately adjust the clamping force through the electric field intensity, can accurately simulate the connection strength of the aircraft wallboard under actual working conditions, and the design of the flexible capsule body and the surface of the test piece avoids clamping damage, greatly improves the simulation authenticity of the boundary constraint condition, and provides a reliable basis for subsequent load testing.

[0023] (2) The present application realizes multi-field coupling loading of static load, dynamic vibration load and sound wave load, completely conforms to the stress environment of the aircraft wallboard in actual flight, and solves the defect of single load type of the traditional device. The electromagnetic coil has the functions of driving and monitoring, can accurately control the frequency and amplitude of dynamic vibration, can capture the displacement state and contact stability of the probe rod in real time, can identify the contact instability working condition in time, the focusing design and damping backing of the sound wave loader effectively reduce the signal interference, ensure the accurate application of the sound wave load, and provide rich data support for comprehensive evaluation of the mechanical properties of the wallboard under complex working conditions.

[0024] (3) The slow-release design of the coupling agent release ring in the application solves the problems of uneven application and easy loss of traditional coupling agents, and the uniformly formed oil film not only ensures the sound wave conduction efficiency, but also realizes the anti-abrasion protection of the test piece surface, prolongs the test life of the test piece. The ultrasonic detection and load loading process are carried out cooperatively, which can capture the dynamic evolution of the internal defects of the wallboard in the loading process in real time, avoid the data lag problem caused by the independent detection and loading of the traditional device, accurately identify the defect position and size through accurate analysis of the echo signal, provide comprehensive and accurate data for the strength evaluation of the wallboard, effectively reduce the flight safety hidden danger, and have important significance for the high-quality development of the aviation industry. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic diagram of the application;

[0026] Figure 2 is a partial sectional view of the test bench part of the application;

[0027] Figure 3 is a structural schematic diagram of the load test assembly of the application;

[0028] Figure 4 is a structural schematic diagram of the load curved surface transmission plate part of the application;

[0029] Figure 5 is a sectional view of the load transmission rod part of the application;

[0030] Figure 6 is a sectional view of the detection rod part of the application;

[0031] Figure 7 is a split structure diagram of the coupling agent release ring of the application;

[0032] Figure 8 is a split structure diagram of the sound wave loader of the application.

[0033] Explanation of reference numerals in the drawing:

[0034] 1, detection platform; 2, fixed back plate; 3, boundary clamp; 31, installation bottom plate; 32, side slot; 33, guide slide; 34, flexible clamping plate; 35, U-shaped flow channel; 36, hydraulic oil pipe; 37, hydraulic piston; 38, synchronous rod; 4, wallboard test piece; 5, load test assembly; 51, arc top plate; 52, hydraulic rod; 53, connecting table; 54, load transmission rod; 541, hollow sleeve; 542, probe rod; 543, magnetic guide rod; 544, connecting plate; 545, tension spring; 546, electromagnetic coil; 55, load curved surface transmission plate; 56, perforation; 6, coupling agent release ring; 61, oil storage ring; 62, microporous sintered metal filter screen; 63, porous polymer release layer; 64, flexible lip-shaped sealing ring; 65, sealing cover; 7, acoustic wave loader; 71, piezoelectric ceramic stack; 72, damping backing; 73, acoustic wave guide. DETAILED DESCRIPTION

[0035] An embodiment of the present application will be described in detail below with reference to the accompanying drawings.

[0036] Example 1

[0037] Please refer to Figures 1-6 An aircraft fuselage wallboard strength test device includes a detection platform 1, a boundary clamp 3 is fixedly installed on the upper end of the detection platform 1, and a wallboard test piece 4 is clamped on the boundary clamp 3, a fixed back plate 2 is fixedly installed at the rear end of the detection platform 1, a load test assembly 5 is fixedly installed at the lower end of the fixed back plate 2, and the load test assembly 5 is located above the wallboard test piece 4.

[0038] The load test assembly 5 includes an arc top plate 51 fixedly installed at the lower end of the fixed back plate 2, a plurality of annular array distributed hydraulic rods 52 fixedly installed at the lower end of the arc top plate 51, a connecting table 53 fixedly installed at the output end of the hydraulic rod 52, a load transmission rod 54 fixedly installed at one end of the connecting table 53 close to the wallboard test piece 4, and a matching load curved surface transmission plate 55 fixedly installed at one end of the load transmission rod 54 close to the wallboard test piece 4.

[0039] The arc top plate 51 is made of aluminum alloy material and is fixedly installed at the lower end of the fixed back plate 2 by bolts, and the arc-shaped structure can disperse the installation stress of the plurality of hydraulic rods 52; the hydraulic rod 52 selects a high-pressure servo hydraulic rod, the cylinder body is made of stainless steel material, the surface of the piston rod is chrome plated, and has high-precision stretching control capability and can apply stable static load. The connecting table 53 is made of alloy steel material and is fixedly installed at the output end of the hydraulic rod 52 through a flange to ensure the stability of load transmission.

[0040] The boundary clamp 3 comprises a mounting base plate 31, the left and right ends of which are provided with side slots 32, and a pair of symmetrical flexible clamping plates 34 are slidably installed in the inner sides of the side slots 32. A pair of guide slides 33 corresponding to the side slots 32 are fixedly installed at the front end of the mounting base plate 31. The wall plate test piece 4 can be guided into the side slots 32 through the guide slides 33, and then the wall plate test piece 4 is adjustably clamped and fixed by the pair of flexible clamping plates 34, which is suitable for wall plate test pieces 4 of different sizes and types.

[0041] A pair of U-shaped flow channels 35 corresponding to the side slots 32 are formed in the mounting base plate 31, and the U-shaped flow channels 35 are connected with a hydraulic oil pump through a hydraulic oil pipe 36. The left and right sides of the U-shaped flow channels 35 are slidably installed with interference-fitted hydraulic pistons 37. The synchronous rods 38 are fixedly installed between the hydraulic pistons 37 and the flexible clamping plates 34. The hydraulic oil is injected into the U-shaped flow channels 35 through the hydraulic oil pipe 36 by the external hydraulic oil pump, and the hydraulic pistons 37 are extruded and moved outward by hydraulic action, and then the flexible clamping plates 34 are pushed to contact and abut against the wall plate test piece 4 through the synchronous rods 38, so that the wall plate test piece 4 is clamped well. It can adapt to wall plate test pieces 4 of different sizes and positions with deviations, such as wall plate test pieces 4 that are not placed in the center before testing or are larger in size, and the outer flexible clamping plates 34 are closer to the outer side. Therefore, under the action of hydraulic pressure, the outer flexible clamping plates 34 will quickly contact and then cannot continue to move. At this time, the hydraulic action is actively applied to the inner flexible clamping plates 34, so that they continue to move until they contact the wall plate test piece 4. Finally, the pair of flexible clamping plates 34 can realize uniform clamping of the wall plate test piece 4 at the boundary. The flexible clamping plates 34 can clasp the wall plate test piece 4 by utilizing the flexible fitting characteristics.

[0042] The flexible clamping plate 34 is a hollow elastic bag-shaped structure and is filled with an electric current variable liquid in the inside, and is electrically connected with an electric field generator. Different strength electric fields are applied to realize different clamping forces, so as to simulate the connection strength of the aircraft wall plate under actual working conditions and improve the boundary simulation effect.

[0043] The flexible clamping plate 34 is a hollow elastic capsule structure, the shell is made of oil-resistant nitrile rubber material, has good elasticity and sealing performance, can tightly fit the edges of wallboard test pieces 4 with different profiles; the inside is filled with electrorheological fluid, which can quickly change viscosity from liquid to solid-like state under the action of electric field, and by applying different intensity of electric field through the electric field generator, the clamping stiffness and force can be accurately adjusted, perfectly simulating the boundary constraint strength of bolt connection, riveting and other boundary constraints of aircraft wallboard under actual working conditions, solving the problem that traditional rigid clamps cannot restore the real boundary state. The U-shaped flow channel 35 and the hydraulic oil pipe 36 are made of stainless steel material, the hydraulic oil pipe 36 is wrapped with a protective sleeve to prevent it from breaking under pressure during testing; the hydraulic piston 37 is made of stainless steel material, and is in interference fit with the U-shaped flow channel 35, with a gap of less than 0.01 mm, ensuring the sealing performance of hydraulic transmission; the synchronous rod 38 is made of alloy steel material, one end is welded and fixed with the hydraulic piston 37, and the other end is connected with the flexible clamping plate 34 through bolts, ensuring uniform transmission of clamping force.

[0044] The load transmission rod 54 includes a hollow sleeve 541, a matching detection rod 542 is slidably installed inside the hollow sleeve 541, and a through hole 56 matched with the detection rod 542 is formed at the lower end of the load curved surface transmission plate 55. The detection rod 542 extends out of the load curved surface transmission plate 55 and reciprocates at a specific frequency to simulate the vibration environment in actual flight to apply dynamic load.

[0045] A magnetic guide rod 543 is fixedly installed at the upper end of the detection rod 542, and an electromagnetic coil 546 corresponding to the magnetic guide rod 543 is fixedly installed inside the hollow sleeve 541. A connecting plate 544 is fixedly installed at the upper end of the magnetic guide rod 543, a tension spring 545 is fixedly installed between the connecting plate 544 and the top wall of the hollow sleeve 541. By controlling the electromagnetic coil 546 to generate a changing magnetic field, the magnetic guide rod 543 is subjected to an attractive-repulsive driving force to drive the detection rod 542 to extend out of the load curved surface transmission plate 55 and reciprocate at a specific frequency to simulate the vibration environment in actual flight and apply dynamic load to the wallboard test piece 4. At the same time, the electromagnetic coil 546 can also act as a sensing coil. According to Faraday's law of electromagnetic induction, when the magnetic guide rod 543 moves relative to the coil, a voltage will be induced in the coil. The amplitude of the induced voltage is proportional to the movement speed of the moving rod. By integrating the induced signal, the dynamic displacement amplitude of the detection rod 542 and the real-time state of the contact between the detection rod 542 and the wallboard test piece 4 can be accurately calculated. The baseline waveform of the induced signal during dynamic excitation is recorded. Once the induced signal is found to have a sharp jump or high-frequency burr, which is a typical feature of instantaneous separation-collision between the detection rod 542 and the wallboard test piece 4, the logic immediately judges that the contact is unstable.

[0046] The hollow sleeve 541 of the load transmission rod 54 is made of stainless steel, and the internally mounted probe rod 542 is made of titanium alloy material. The titanium alloy has high strength and light weight characteristics, can maintain structural stability under high-frequency vibration, and avoids affecting the test accuracy due to its own deformation. The magnetic guide rod 543 at the upper end of the probe rod 542 is made of neodymium-iron-boron permanent magnet, which has high magnetic strength and can produce strong magnetic interaction with the electromagnetic coil 546. The electromagnetic coil 546 is wound by high-purity copper enameled wire, and has uniform winding density. After being electrified, it can generate a stable changing magnetic field. By controlling the current direction and intensity, the probe rod 542 can be driven to reciprocate at a specific frequency by the attraction-repulsion alternation of the magnetic guide rod 543. The connecting plate 544 is made of aluminum alloy material and is welded and fixed with the magnetic guide rod 543. The tension spring 545 is made of stainless spring steel material and is processed by heat treatment process. The elastic recovery performance is stable, which provides a reset force for the probe rod 542 and ensures the accuracy of the vibration frequency. The load curved surface transmission plate 55 is made of polyurethane elastic material, and the surface is attached to the contour design of the wallboard test piece 4. The load can be uniformly transmitted to the surface of the test piece to avoid test errors caused by local stress concentration.

[0047] Embodiment 2:

[0048] Please refer to Figure 6 and Figure 8 The lower end of the probe rod 542 is provided with a sound emitting groove, and a sound wave loader 7 is installed in the sound emitting groove. The sound wave loader 7 simulates the sound wave fatigue test during the flight of the airplane, realizes multi-field coupling loading, and further comprehensively evaluates the mechanical response and stability of the connecting structure under complex working conditions.

[0049] The sound wave loader 7 includes a piezoelectric ceramic stack 71, a damping backing 72 fixedly installed between the upper end of the piezoelectric ceramic stack 71 and the top wall of the sound emitting groove, and a sound wave guide 73 fixedly installed at the lower end of the piezoelectric ceramic stack 71. High-frequency sound waves generated by the piezoelectric ceramic stack 71 are conducted to the wallboard test piece 4 through the sound wave guide 73. The damping backing 72 can prevent the sound waves from propagating backward to cause signal reception interference. At the moment when detection is needed, dynamic loading is paused or the piezoelectric ceramic stack 71 is used in the interval. An ultrasonic instrument emits a high-voltage electric pulse to the piezoelectric ceramic stack 71. The piezoelectric ceramic stack 71 generates high-frequency vibration, which is focused and conducted to the wallboard test piece 4 through the sound wave guide 73. When the sound wave propagates in the wallboard test piece 4, it will be reflected when encountering defects or boundaries. The echo is collected by the same sound wave guide 73 and transmitted back to the piezoelectric ceramic stack 71. The piezoelectric ceramic stack 71 converts the mechanical vibration back to an electric signal, which is received and analyzed by the ultrasonic instrument.

[0050] The piezoelectric ceramic stack 71 is stacked by 12 pieces of PZT-5H type piezoelectric ceramic sheets, each with a diameter of 10 mm, a thickness of 1 mm, a total height of 12 mm, and a polarization direction along the thickness direction. The electrodes of adjacent ceramic sheets are reversely connected in parallel to increase the output amplitude, and the maximum displacement output can reach 50 μm. The damping backing 72 at the upper end of the piezoelectric ceramic stack 71 is made of high-damping butyl rubber material, which effectively blocks the propagation of sound waves into the hollow sleeve 541, avoiding interference with the induction signal of the electromagnetic coil 546. The sound wave guide 73 fixed at the lower end of the piezoelectric ceramic stack 71 is made of TC4 titanium alloy material, with a diameter of 10 mm and a length of 6 mm. The lower end is processed into a semispherical focusing surface with a curvature radius of 4 mm, which facilitates the focusing and conduction of high-frequency sound waves to the surface of the wallboard test piece 4. The frequency range of the sound waves can be adjusted between 20 kHz and 2 MHz. The power supply of the sound wave loader 7 is provided by a special high-voltage power supply, with an output voltage of 0-2000V adjustable. At the same time, the emission and reception of pulse signals are realized through an ultrasonic instrument, which is powered by 220V alternating current. The ultrasonic instrument is equipped with a built-in signal amplifier and filter, and the amplification factor can be adjusted between 1000 and 10000 times. The filter center frequency is 5-20 MHz.

[0051] Example 3:

[0052] Please refer to Figures 6-7 The lower end of the probe rod 542 is fixedly installed with a matching coupling agent release ring 6, and the sound wave guide 73 extends to the bottom surface of the coupling agent release ring 6. The coupling agent release ring 6 can actively release the coupling agent during the test, which can prevent the wallboard test piece 4 from being worn during the test, and the oil film formed can effectively conduct the excitation sound waves generated by the sound wave loader 7.

[0053] The coupling agent release ring 6 includes an oil storage ring 61, a microporous sintered metal filter screen 62, a porous polymer release layer 63, and a flexible lip-shaped sealing ring 64 installed in sequence at the lower end of the oil storage ring 61. A sealing cover 65 is installed at the upper end of the oil storage ring 61. When the static load is applied, the flexible lip-shaped sealing ring 64 is pressed after contacting the wallboard test piece 4, and a gap is formed between the probe rod 542, and the porous polymer release layer 63 is slowly released by the internal pressure to form an oil film on the surface of the wallboard test piece 4.

[0054] The oil storage ring 61 is made of stainless steel, with an inner diameter of 15 mm, an outer diameter of 25 mm, a height of 8 mm, and an internal oil storage cavity volume of about 3 mL. The sealing cover 65 at the upper end is made of polytetrafluoroethylene material and is connected with the oil storage ring 61 through M16 threads. Fluorine rubber sealing pads are arranged at the threads to ensure that the coupling agent does not leak. The microporous sintered metal filter screen 62, the porous polymer release layer 63, and the flexible lip-shaped sealing ring 64 are sequentially arranged at the lower end of the oil storage ring 61 to cooperatively realize the slow release and uniform distribution of the coupling agent. The microporous sintered metal filter screen 62 is made of TC4 titanium alloy, with a thickness of 1.5 mm and a pore size of 5-10 μm, which plays a role in filtering impurities and buffering the flow rate of the coupling agent. The porous polymer release layer 63 is made of polyvinyl formal foam, with a thickness of 2 mm and a pore size of 10-20 μm, which has good liquid retention and can control the release rate of the coupling agent to be 0.05-0.1 mL / min. The flexible lip-shaped sealing ring 64 is made of fluorine rubber material, with a Shore hardness of 55A, an inner diameter of 12 mm, an outer diameter of 28 mm, and a lip angle of 45°. When the load curved surface transmission plate 55 contacts the wall plate specimen 4, the lip-shaped sealing ring is deformed under pressure to form a sealed cavity with the surface of the wall plate, and the internal pressure is used to promote the slow seepage of the coupling agent to form a uniform oil film with a thickness of 50-100 μm. The coupling agent used is glyceryl coupling agent, with a viscosity of 50-100 mPa·s, which has good sound wave conduction and anti-wear performance.

[0055] It should be noted that the device uses a PLC controller as the core, with a model of S7-1200. The analog output module, digital input / output module, and communication module are used to realize the cooperative control of each component. The PLC controller is connected with the electric field generator through the RS485 communication interface, outputs a 0-10V control signal to adjust the electric field intensity, generates a 50-500Hz adjustable PWM signal through the pulse output module to control the driving circuit of the electromagnetic coil 546, realizes the precise regulation and control of the reciprocating frequency and amplitude of the probe rod 542, and is linked with the ultrasonic instrument through the communication interface to control the emission time point of the ultrasonic pulse. Usually, the pulse is emitted at the moment when the probe rod 542 is at the maximum elongation and stably contacts the wall plate specimen 4 to avoid vibration interference. The echo signal is transmitted to the data acquisition card after being processed by the ultrasonic instrument, and is analyzed and processed by the upper computer software.

[0056] Working principle:

[0057] First, the installation and fixation of the wallboard test piece 4 are carried out: the wallboard test piece 4 to be tested is slid into the side slot 32 of the boundary clamp 3 along the guide slide 33, the external hydraulic oil pump is started, the hydraulic oil is injected into the U-shaped flow channel 35 in the installation bottom plate 31 through the hydraulic oil pipe 36, the pressure generated by the hydraulic oil extrudes the hydraulic pistons 37 on both sides, the hydraulic pistons 37 push the flexible clamping plates 34 to move towards the wallboard test piece 4 through the synchronous rod 38. If the wallboard test piece 4 is not centered or has size difference, one side of the flexible clamping plate 34 first contacts the test piece and cannot continue to move, the hydraulic pressure will actively act on the other side of the hydraulic piston 37, and the other side of the flexible clamping plate 34 will continue to move until it contacts the test piece, so that the uniformity of the clamping force on both sides is finally realized. Then the electric field generator is started, and a specific intensity of electric field is applied to the electrorheological fluid in the flexible clamping plate 34, the viscosity of the electrorheological fluid is changed by adjusting the electric field intensity, and then the clamping force is adjusted, the connection strength of the aircraft wallboard under the actual working condition is accurately simulated, and the flexible capsule is flexibly attached to the surface of the test piece, so that damage to the test piece during clamping is avoided.

[0058] Next, the load test assembly 5 is started to apply a multi-field coupled load: first, the hydraulic rod 52 is controlled to synchronously elongate, the connecting table 53, the load transmission rod 54 and the load curved surface transmission plate 55 are pushed to move downward until the load curved surface transmission plate 55 stably contacts the surface of the wallboard test piece 4, the output pressure of the hydraulic rod 52 is adjusted through the hydraulic control system to apply a preset static load. At the same time, the PLC controller outputs a PWM control signal to the electromagnetic coil 546, the electromagnetic coil 546 generates a periodically changing magnetic field, and the magnetic guide rod 543 generates alternating attractive force and repulsive force, under the resetting action of the tension spring 545, the magnetic guide rod 543 drives the probe rod 542 to do reciprocating extension and contraction motion along the hollow sleeve 541, the probe rod 542 penetrates the perforation 56 of the load curved surface transmission plate 55, and a dynamic vibration load is applied to the wallboard test piece 4 at a specific frequency of 50-500 Hz to simulate the vibration environment in the flight process. In this process, the electromagnetic coil 546 simultaneously acts as a sensing coil, according to the Faraday's law of electromagnetic induction, when the magnetic guide rod 543 is driven to move by the probe rod 542, a voltage will be induced in the coil, the amplitude of the induced voltage is proportional to the speed of movement, and the dynamic displacement amplitude of the probe rod 542 can be accurately calculated by integrating the induced signal, and the contact state of the probe rod 542 with the wallboard test piece 4 is monitored at the same time, if the induced signal appears sharp jump or high frequency burr, it is immediately judged as "contact instability" and a prompt is given.

[0059] Subsequently, the sound wave loader 7 is started to perform a sound wave fatigue test: the piezoelectric ceramic stack 71 generates high-frequency vibration under the drive of a high-voltage power supply, forms a high-frequency sound wave excitation, and the sound wave is focused on the surface of the wallboard test piece 4 after being focused by the focusing surface of the sound wave guide 73, so as to realize the application of the sound wave load and simulate the fatigue effect of the engine sound wave on the wallboard during the flight of the airplane. The damping backing 72 effectively blocks the sound wave from propagating to the inside of the hollow sleeve 541, avoids interference with the induction signal of the electromagnetic coil 546, realizes the cooperative application of the vibration load and the sound wave load, and achieves multi-field coupling loading. During the load application process, the coupling agent release ring 6 synchronously realizes the release of the coupling agent: after the flexible lip-shaped sealing ring 64 contacts the wallboard test piece 4, it is deformed under extrusion, and a small gap is formed between the flexible lip-shaped sealing ring 64 and the detection rod 542. The coupling agent in the oil storage ring 61 is filtered through the microporous sintered metal filter 62 and slowly released through the porous polymer release layer 63 under the action of internal pressure, and finally seeps out to the surface of the wallboard test piece 4 to form a uniform oil film, which not only avoids the wear of the test piece during reciprocating vibration, but also ensures that the sound wave generated by the sound wave loader 7 can be efficiently conducted.

[0060] When it is necessary to detect defects of the wallboard test piece 4, the PLC controller controls to pause the dynamic vibration loading, or uses the stable period of the vibration gap to send a control signal to the ultrasonic instrument, the ultrasonic instrument emits a 0-2000V high-voltage electric pulse to the piezoelectric ceramic stack 71, the piezoelectric ceramic stack 71 generates high-frequency ultrasonic vibration, which is focused and conducted to the inside of the wallboard test piece 4 through the sound wave guide 73. When the sound wave propagates in the test piece, it will be reflected if it encounters a defect or a boundary, and the reflected echo is collected by the sound wave guide 73 and transmitted back to the piezoelectric ceramic stack 71. The piezoelectric ceramic stack 71 converts the mechanical vibration into an electric signal, which is amplified and filtered by the ultrasonic instrument and then transmitted to the upper computer. Through software analysis of the amplitude, phase and other parameters of the echo signal, the defect position and size inside the wallboard test piece 4 are accurately identified, and the comprehensive evaluation of the strength and defects is completed.

[0061] The above merely describes a preferred embodiment of the present application; however, the protection scope of the present application is not limited thereto. Any person skilled in the art can make equivalent replacements or changes to the technical solution and the improvement concept of the present application within the technical range disclosed by the present application, which should be covered by the protection scope of the present application.

Claims

1. A device for testing the strength of aircraft fuselage panels, characterized in that: The test bench (1) is fixedly installed with a boundary clamp (3) on its upper end, and a wall panel specimen (4) is clamped on the boundary clamp (3). A fixed back plate (2) is fixedly installed at the rear end of the test bench (1). A load testing component (5) is fixedly installed at the lower end of the fixed back plate (2), and the load testing component (5) is located above the wall panel specimen (4). The load testing assembly (5) includes an arc-shaped top plate (51) fixedly installed at the lower end of the fixed back plate (2). Multiple hydraulic rods (52) arranged in a ring array are fixedly installed at the lower end of the arc-shaped top plate (51). A connecting platform (53) is fixedly installed at the output end of the hydraulic rods (52). A load transfer rod (54) is fixedly installed at one end of the connecting platform (53) near the wall plate specimen (4). A matching load curved surface transfer plate (55) is fixedly installed at one end of the load transfer rod (54) near the wall plate specimen (4). The load transfer rod (54) includes a hollow sleeve (541), a matching probe rod (542) is slidably installed inside the hollow sleeve (541), a through hole (56) matching the probe rod (542) is opened at the lower end of the load curved transfer plate (55), a magnetic guide rod (543) is fixedly installed at the upper end of the probe rod (542), an electromagnetic coil (546) corresponding to the magnetic guide rod (543) is fixedly installed inside the hollow sleeve (541), a connecting plate (544) is fixedly installed at the upper end of the magnetic guide rod (543), and a tension spring (545) is fixedly installed between the connecting plate (544) and the top wall of the hollow sleeve (541).

2. The aircraft fuselage panel strength testing device according to claim 1, characterized in that: The boundary clamp (3) includes a mounting base plate (31), with side slots (32) at both the left and right ends of the mounting base plate (31). A pair of symmetrically distributed flexible clamping plates (34) are slidably installed inside the side slots (32), and a pair of guide slides (33) corresponding to the side slots (32) are fixedly installed at the front end of the mounting base plate (31).

3. The aircraft fuselage panel strength testing device according to claim 2, characterized in that: The mounting base plate (31) has a pair of U-shaped flow channels (35) corresponding to the side slots (32). The U-shaped flow channels (35) are connected to a hydraulic oil pump through hydraulic oil pipes (36). The left and right openings of the U-shaped flow channels (35) are slidably installed with interference fit hydraulic pistons (37). A synchronizing rod (38) is fixedly installed between the hydraulic pistons (37) and the flexible clamping plate (34).

4. The aircraft fuselage panel strength testing device according to claim 3, characterized in that: The flexible clamping plate (34) is a hollow elastic capsule structure filled with electrorheological fluid and electrically connected to an electric field generator.

5. The aircraft fuselage panel strength testing device according to claim 1, characterized in that: The lower end of the probe rod (542) is provided with a sound-emitting groove, and a sound wave loader (7) is installed in the sound-emitting groove.

6. The aircraft fuselage panel strength testing device according to claim 5, characterized in that: The acoustic loader (7) includes a piezoelectric ceramic stack (71), a damping backing (72) is fixedly installed between the upper end of the piezoelectric ceramic stack (71) and the top wall of the sound-generating groove, and an acoustic waveguide (73) is fixedly installed at the lower end of the piezoelectric ceramic stack (71).

7. The aircraft fuselage panel strength testing device according to claim 6, characterized in that: The lower end of the probe rod (542) is fixedly installed with a matching couplant release ring (6), and the acoustic waveguide (73) extends to the bottom surface of the couplant release ring (6).

8. The aircraft fuselage panel strength testing device according to claim 7, characterized in that: The coupling agent release ring (6) includes an oil storage ring (61), and a microporous sintered metal filter (62), a porous polymer release layer (63) and a flexible lip seal (64) are sequentially installed at the lower end of the oil storage ring (61). A sealing cap (65) is installed at the upper end of the oil storage ring (61).

Images