Aircraft fuselage wall panel strength test device

Abstract

The invention discloses an aircraft fuselage wall panel strength test device, and belongs to the technical field of aircraft wall panel testing, the aircraft fuselage wall panel strength test device comprises a detection table, a fixed backboard, a boundary clamp, a wall panel test piece and a load test assembly, the boundary clamp realizes self-adaptive clamping by hydraulically driving a flexible clamping plate, and the flexible clamping plate is filled with electrorheological fluid; the clamping force can be accurately adjusted and the actual connection strength can be simulated by matching with an electric field generator, the load testing assembly applies a static load through a hydraulic rod, an electromagnetic coil of a load transmission rod drives a detection rod to stretch out and draw back in a reciprocating mode and applies a dynamic vibration load, and meanwhile the monitoring function is achieved; the acoustic fatigue test is realized, static, dynamic and acoustic 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 test accuracy and reliability are greatly improved, and powerful support is provided for research and development of the aviation wallboard.

Description

Technical Field

[0001] This invention relates to the field of aircraft fuselage panel testing technology, and more specifically, to an aircraft fuselage panel strength testing device. Background Technology

[0002] As a core load-bearing component of aircraft, the fuselage panels directly bear the complex mechanical forces of aerodynamic loads, structural vibrations, and engine acoustic fatigue during flight. Their structural strength and stability are directly related to flight safety. With the aviation industry's development towards higher load capacities, longer lifespans, and lighter weights, the reliability requirements for aircraft fuselage panels are increasingly stringent. Therefore, precise strength testing equipment is needed to simulate the stress environment under actual operating conditions and comprehensively evaluate the mechanical response and structural safety of the panels.

[0003] Currently, existing aircraft fuselage panel strength testing equipment has many shortcomings and cannot meet the needs of accurate testing. Regarding boundary clamping, traditional devices mostly use rigid clamps with fixed clamping dimensions, resulting in poor adaptability and an inability to meet the testing requirements of panel specimens of different specifications and shapes. Furthermore, the clamping force is not adjustable, making it difficult to simulate the connection strength between the panel and the fuselage under actual working conditions. Rigid clamping also easily leads to edge damage to the specimens, affecting the accuracy of the test results. Some improved devices use hydraulically driven clamping, but lack adaptive adjustment capabilities. When the panel specimen is misaligned or has dimensional deviations, uniform clamping cannot be achieved, leading to significant differences between the boundary constraints and actual working conditions.

[0004] Regarding load application, existing devices primarily employ single static loads or simple dynamic loads, failing to achieve the coordinated application of vibration and acoustic loads. However, aircraft panels often experience the coupled effects of vibration and acoustic waves during actual flight, making single-load tests insufficient to comprehensively reflect the panel's true mechanical properties. Furthermore, the monitoring accuracy of dynamic loads is insufficient, failing to accurately obtain the contact state between the specimen and the loading mechanism, and making it difficult to identify critical conditions such as contact instability, resulting in incomplete test data. Summary of the Invention

[0005] 1. Technical problems to be solved To address the problems existing in the prior art, the present invention aims to provide an aircraft fuselage panel strength testing device that can realize static, dynamic, and acoustic multi-field coupled loading, combined with ultrasonic defect detection, accurately simulate actual working conditions, comprehensively evaluate the mechanical response and stability of the panel, significantly improve the accuracy and reliability of testing, and provide strong support for the research and development of aerospace panels.

[0006] 2. Technical Solution To solve the above problems, the present invention adopts the following technical solution.

[0007] An aircraft fuselage panel strength testing device includes a testing platform, a boundary clamp fixedly installed at the upper end of the testing platform, a panel specimen clamped on the boundary clamp, a fixed back plate fixedly installed at the rear end of the testing platform, and a load testing component fixedly installed at the lower end of the fixed back plate, with the load testing component located above the panel specimen. The load testing assembly includes an arc-shaped top plate fixedly installed at the lower end of a fixed back plate. Multiple hydraulic rods arranged in a ring array are fixedly installed at the lower end of the arc-shaped top plate. A connecting platform is fixedly installed at the output end of each hydraulic rod. A load transfer rod is fixedly installed at the end of the connecting platform near the wall panel specimen. A matching load curved surface transfer plate is fixedly installed at the end of the load transfer rod near the wall panel specimen.

[0008] As a further improvement of the present invention, the boundary fixture includes a mounting base plate, with side slots at both ends of the mounting base plate. A pair of symmetrically distributed flexible clamping plates are slidably installed inside the side slots. A pair of guide slides corresponding to the side slots are fixedly installed at the front end of the mounting base plate. The guide slides can guide the wall panel specimen into the side slots, and then the wall panel specimen is adjustablely clamped and fixed by the pair of flexible clamping plates to adapt to wall panel specimens of different sizes and types.

[0009] As a further improvement of the present invention, the mounting base plate has a pair of U-shaped flow channels corresponding to the side slots. The U-shaped flow channels are connected to a hydraulic pump via hydraulic oil pipes. Hydraulic pistons with interference fits are slidably installed at the openings on both sides of the U-shaped flow channels. A synchronizing rod is fixedly installed between the hydraulic pistons and the flexible clamping plate. Hydraulic oil is injected into the U-shaped flow channels through hydraulic oil pipes via an external hydraulic pump. The hydraulic pressure forces the hydraulic pistons to move outwards, which in turn pushes the flexible clamping plate to contact and press against the wall plate specimen via the synchronizing rod, thus providing good clamping. To accommodate wall panel specimens of different sizes and with positional deviations, such as those that were not centered before testing or were large in size with their outer edges close to the outer flexible clamping plates, the outer flexible clamping plates will quickly make contact under hydraulic pressure and then be unable to move further. At this point, the hydraulic pressure is actively applied to the inner flexible clamping plates, causing them to continue moving until they contact the wall panel specimen. Ultimately, a pair of flexible clamping plates can achieve uniform clamping force on both sides of the wall panel specimen boundary. The flexible clamping plates can flexibly clamp the wall panel specimen by utilizing their flexible fitting characteristics.

[0010] As a further improvement of the present invention, the flexible clamping plate is a hollow elastic capsule structure filled with electrorheological fluid and electrically connected to an electric field generator. By applying electric fields of different intensities, clamping with different forces can be achieved, thereby simulating the connection strength of aircraft panels under actual working conditions and improving the boundary simulation effect.

[0011] As a further improvement of the present invention, the load transfer rod includes a hollow sleeve, and a matching probe rod is slidably installed on the inner side of the hollow sleeve. The lower end of the load curved transfer plate has a through hole that matches the probe rod. The probe rod extends out of the load curved transfer plate and reciprocates at a specific frequency to simulate the vibration environment in actual flight to apply dynamic load.

[0012] As a further improvement of the present invention, a magnetic guide rod is fixedly installed at the upper end of the probe rod, and 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, and a tension spring is fixedly installed between the connecting plate and the top wall of the hollow sleeve. By controlling the electromagnetic coil to generate a changing magnetic field, an attraction-repulsion driving force is applied to the magnetic guide rod, causing it to drive the probe rod to extend out of the load-bearing curved plate and reciprocate at a specific frequency, simulating the vibration environment in actual flight and applying a dynamic load to the wall panel specimen. At the same time, the electromagnetic coil can also... As a sensing coil, according to Faraday's law of electromagnetic induction, when the magnetic rod moves relative to the coil, a voltage will be induced in the coil. The amplitude of the induced voltage is proportional to the speed of the moving rod. By integrating and processing the induced signal, the dynamic displacement amplitude of the probe rod and the real-time state of contact between the probe rod and the wall panel specimen can be accurately calculated. The reference waveform of the induced signal during dynamic excitation is recorded. Once a violent jump or high-frequency spike is detected in the induced signal, this is a typical characteristic of the probe rod and the wall panel specimen undergoing instantaneous separation-collision. The logic immediately judges it as "contact instability".

[0013] As a further improvement of the present invention, a sound-emitting groove is provided at the lower end of the probe rod, and an acoustic loader is installed in the sound-emitting groove to simulate the acoustic fatigue test during aircraft flight, realize multi-field coupled loading, and thus comprehensively evaluate the mechanical response and stability of the connection structure under complex working conditions.

[0014] As a further improvement of the present invention, the acoustic loading device includes a piezoelectric ceramic stack. A damping backing is fixedly installed between the upper end of the piezoelectric ceramic stack and the top wall of the sound-generating groove. An acoustic waveguide is fixedly installed at the lower end of the piezoelectric ceramic stack. The high-frequency acoustic wave excitation generated by the piezoelectric ceramic stack is transmitted to the wall panel specimen through the acoustic waveguide. The damping backing can prevent the acoustic wave from propagating backward and causing signal reception interference. At the moment when testing is required, the dynamic loading is paused or its interval is utilized. The ultrasonic instrument emits a high-voltage electric pulse to the piezoelectric ceramic stack, which generates high-frequency vibration. The vibration is focused and transmitted to the wall panel specimen through the acoustic waveguide. The acoustic wave propagates in the wall panel specimen and will be reflected when it encounters defects or boundaries. The echo is collected by the same acoustic waveguide and transmitted back to the piezoelectric ceramic stack. The piezoelectric ceramic stack converts the mechanical vibration back into an electrical signal, which is received and analyzed by the ultrasonic instrument.

[0015] As a further improvement of the present invention, a matching couplant release ring is fixedly installed at the lower end of the probe rod, and the acoustic waveguide extends to the bottom surface of the couplant release ring. The couplant release ring can actively release couplant during the test, which can prevent the wall panel specimen from being worn during the test, and the oil film formed can effectively conduct the excitation acoustic wave generated by the acoustic loader.

[0016] As a further improvement of the present invention, the coupling agent release ring includes an oil storage ring. The lower end of the oil storage ring is sequentially equipped with a microporous sintered metal filter, a porous polymer release layer, and a flexible lip seal. The upper end of the oil storage ring is equipped with a sealing cap. When a static load is applied, the flexible lip seal is squeezed after contacting the wall plate specimen and a gap is formed between it and the probe rod. The internal pressure causes the porous polymer release layer to slowly release the coupling agent and form an oil film on the surface of the wall plate specimen.

[0017] 3. Beneficial Effects Compared with the prior art, the advantages of this invention are: (1) This invention achieves adaptive adjustment through a hydraulically driven flexible clamping plate, which can adapt to wall panel specimens of different sizes and placement positions, solving the problem of poor adaptability of traditional rigid clamps. The hydraulic drive ensures uniform clamping force on both sides, avoiding test errors caused by uneven clamping. At the same time, the electrorheological fluid in the flexible clamping plate can precisely adjust the clamping force through the electric field strength, which can accurately simulate the connection strength of aircraft wall panels under actual working conditions. The fit design between the flexible capsule and the surface of the specimen avoids clamping damage, greatly improving the simulation realism of boundary constraint conditions and providing a reliable foundation for subsequent load testing.

[0018] (2) This invention innovatively realizes multi-field coupled loading of static load, dynamic vibration load and acoustic load, which perfectly matches the stress environment of the aircraft panel in actual flight, and solves the defect of the single load type of traditional devices. The electromagnetic coil has both driving and monitoring functions. It can not only accurately control the frequency and amplitude of dynamic vibration, but also capture the displacement state and contact stability of the probe rod in real time, and promptly identify contact instability conditions. The focusing design and damping backing of the acoustic loader effectively reduce signal interference and ensure the accurate application of acoustic load, providing rich data support for the comprehensive evaluation of the mechanical performance of the panel under complex working conditions.

[0019] (3) The slow-release design of the coupling agent release ring in this invention solves the problems of uneven application and easy loss of traditional coupling agents. The uniformly formed oil film not only ensures the sound wave transmission efficiency, but also achieves wear protection on the surface of the specimen, extending the test life of the specimen. The ultrasonic testing and load loading process are carried out in tandem, which can capture the dynamic evolution of internal defects in the panel in real time during the loading process. This avoids the data lag problem caused by the independent testing and loading of traditional devices. Through precise analysis of the echo signal, the location and size of defects can be accurately identified, providing comprehensive and accurate data for panel strength assessment. This effectively reduces flight safety hazards and is of great significance to the high-quality development of the aviation industry. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a partial cross-sectional view of the test bench portion of the present invention; Figure 3 This is a schematic diagram of the load testing component of the present invention; Figure 4 This is a schematic diagram of the load transfer plate portion of the present invention; Figure 5 This is a cross-sectional view of the load transfer rod portion of the present invention; Figure 6 This is a cross-sectional view of the probe portion of the present invention; Figure 7 This is a split structural diagram of the coupling agent release ring of the present invention; Figure 8 This is a split structural diagram of the acoustic wave loader of the present invention.

[0021] Explanation of the labels in the diagram: 1. Testing table; 2. Fixed back plate; 3. Boundary clamp; 31. Mounting base plate; 32. Side slot; 33. Guide slide; 34. Flexible clamping plate; 35. U-shaped flow channel; 36. Hydraulic oil pipe; 37. Hydraulic piston; 38. Synchronizing rod; 4. Wall panel specimen; 5. Load testing assembly; 51. Arc-shaped top plate; 52. Hydraulic rod; 53. Connecting platform; 54. Load transfer rod; 541. Hollow sleeve; 542. Detector 543. Magnetic rod; 544. Connecting plate; 545. Tension spring; 546. Electromagnetic coil; 55. Load transfer plate; 56. Perforation; 6. Coupling release ring; 61. Oil reservoir ring; 62. Microporous sintered metal filter; 63. Porous polymer release layer; 64. Flexible lip seal; 65. Sealing cap; 7. Acoustic wave loader; 71. Piezoelectric ceramic stack; 72. Damping backing; 73. Acoustic waveguide. Detailed Implementation

[0022] The following describes one embodiment of this application in detail with reference to the accompanying drawings.

[0023] Example 1: Please see Figures 1-6 An aircraft fuselage panel strength testing device includes a testing table 1, a boundary clamp 3 fixedly installed on the upper end of the testing table 1, a panel specimen 4 clamped on the boundary clamp 3, a fixed back plate 2 fixedly installed at the rear end of the testing table 1, a load testing component 5 fixedly installed at the lower end of the fixed back plate 2, and the load testing component 5 is located above the 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.

[0024] The curved top plate 51 is made of aluminum alloy and is bolted to the lower end of the fixed back plate 2. Its curved structure can distribute the installation stress of multiple hydraulic rods 52. The hydraulic rods 52 are high-pressure servo hydraulic rods with stainless steel cylinders and chrome-plated piston rods, providing high-precision telescopic control and the ability to apply stable static loads. The connecting platform 53 is made of alloy steel and is fixed to the output end of the hydraulic rods 52 via flanges to ensure the stability of load transmission.

[0025] The boundary fixture 3 includes a mounting base plate 31. Side slots 32 are provided at both ends of the mounting base plate 31. A pair of symmetrically distributed flexible clamping plates 34 are slidably installed inside 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 panel specimen 4 can be guided into the side slots 32 through the guide slides 33. Then, the wall panel specimen 4 is adjustablely clamped and fixed by the pair of flexible clamping plates 34 to adapt to wall panel specimens 4 of different sizes and types.

[0026] 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 pump via hydraulic oil pipes 36. Hydraulic pistons 37 with interference fits are slidably installed at the openings on both sides of the U-shaped flow channels 35. Synchronizing rods 38 are fixedly installed between the hydraulic pistons 37 and the flexible clamping plate 34. Hydraulic oil is injected into the U-shaped flow channels 35 through the hydraulic oil pipes 36 via an external hydraulic pump. The hydraulic pressure forces the hydraulic pistons 37 to move outwards, which in turn pushes the flexible clamping plate 34 to contact and press against the wall plate specimen 4 via the synchronizing rods 38, thus providing good clamping. Different sizes and positions of the wall panel specimen 4 are used. For example, if the wall panel specimen 4 is not centered or is large in size before testing, and the outer edge surface is close to the outer flexible clamping plate 34, the outer flexible clamping plate 34 will quickly make contact under hydraulic action and then cannot continue to move. At this time, the hydraulic action actively acts on the inner flexible clamping plate 34, so that it continues to move until it contacts the wall panel specimen 4. Finally, a pair of flexible clamping plates 34 can achieve uniform clamping force on both sides of the boundary of the wall panel specimen 4. The flexible clamping plate 34 can flexibly clamp the wall panel specimen 4 by utilizing its flexible fitting characteristics.

[0027] The flexible clamping plate 34 is a hollow elastic capsule structure filled with electrorheological fluid and electrically connected to an electric field generator. By applying electric fields of different intensities, clamping with different forces can be achieved, thereby simulating the connection strength of aircraft panels under actual working conditions and improving the boundary simulation effect.

[0028] The flexible clamping plate 34 is a hollow, elastic capsule structure. Its outer shell is made of oil-resistant nitrile rubber, providing excellent elasticity and sealing, allowing it to tightly conform to the edges of the wall panel specimen 4 with varying contours. The interior is filled with an electrorheological fluid, which rapidly changes viscosity under an electric field, transforming from a liquid to a near-solid state. By applying electric fields of varying intensities through an electric field generator, the clamping stiffness and force can be precisely adjusted, perfectly simulating the boundary constraint strength of bolted connections and riveting on aircraft wall panels under actual working conditions. This solves the problem of traditional rigid clamps failing to reproduce the true boundary state. The U-shaped flow channel 35 and hydraulic oil pipe 36 are both made of stainless steel. The hydraulic oil pipe 36 is encased in a protective sleeve to prevent rupture under pressure during testing. The hydraulic piston 37 is made of stainless steel and is interference-fitted with the U-shaped flow channel 35 with a clearance of less than 0.01 mm, ensuring the sealing of the hydraulic transmission. The synchronizing rod 38 is made of alloy steel, with one end welded to the hydraulic piston 37 and the other end bolted to the flexible clamping plate 34, ensuring uniform transmission of clamping force.

[0029] The load transfer rod 54 includes a hollow sleeve 541, and a matching probe rod 542 is slidably installed inside the hollow sleeve 541. The lower end of the load curved transfer plate 55 has a through hole 56 that matches the probe rod 542. The probe rod 542 extends out of the load curved transfer plate 55 and reciprocates at a specific frequency to simulate the vibration environment in actual flight to apply dynamic load.

[0030] 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. 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, an adsorption-repulsion driving force is applied to the magnetic guide rod 543, causing it to drive the probe rod 542 to extend out of the load-bearing curved transfer plate 55 and reciprocate at a specific frequency, simulating the vibration environment in actual flight and applying a dynamic load to the wall panel specimen 4. At the same time, the electromagnetic coil 546... 46 can also be used as a sensing coil. According to Faraday's law of electromagnetic induction, when the magnetic 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 speed of the moving rod. By integrating and processing the induced signal, the dynamic displacement amplitude of the probe rod 542 and the real-time contact state between the probe rod 542 and the wall plate specimen 4 can be accurately calculated. The reference waveform of the induced signal during dynamic excitation is recorded. Once a violent jump or high-frequency spike is detected in the induced signal, this is a typical characteristic of the instantaneous separation-collision between the probe rod 542 and the wall plate specimen 4. The logic immediately judges it as "contact instability".

[0031] The hollow sleeve 541 of the load transfer rod 54 is made of stainless steel, and the probe rod 542 installed inside is made of titanium alloy. Titanium alloy has both high strength and lightweight characteristics, and can maintain structural stability under high frequency vibration, avoiding deformation that affects test accuracy. The magnetic guide rod 543 at the upper end of the probe rod 542 uses neodymium iron boron permanent magnet, which has high magnetic strength and can generate strong magnetic interaction with the electromagnetic coil 546. The electromagnetic coil 546 is made of high-purity copper enameled wire with uniform winding density. After being energized, it can generate a stable changing magnetic field. By controlling the direction and intensity of the current, the magnetic guide rod 543 is driven by alternating attraction and repulsion, thereby driving the probe rod 542 to reciprocate and extend at a specific frequency. The connecting plate 544 is made of aluminum alloy and is welded and fixed to the magnetic guide rod 543. The tension spring 545 is made of stainless steel spring steel and is processed by heat treatment. Its elastic recovery performance is stable, providing the restoring force for the probe rod 542 and ensuring the accuracy of the vibration frequency. The load transfer plate 55 is made of polyurethane elastic material and its surface is designed to fit the contour of the wall plate specimen 4. This allows the load to be transferred evenly to the surface of the specimen, avoiding test errors caused by local stress concentration.

[0032] Example 2: Please see Figure 6 and Figure 8 The lower end of the probe rod 542 is provided with a sound-emitting groove, and the sound wave loader 7 is installed in the sound-emitting groove to simulate the sound wave fatigue test during aircraft flight, realize multi-field coupled loading, and then comprehensively evaluate the mechanical response and stability of the connection structure under complex working conditions.

[0033] The acoustic loading device 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. An acoustic waveguide 73 is fixedly installed at the lower end of the piezoelectric ceramic stack 71. The high-frequency acoustic excitation generated by the piezoelectric ceramic stack 71 is transmitted to the wall panel specimen 4 through the acoustic waveguide 73. The damping backing 72 can prevent the acoustic waves from propagating backward and causing signal reception interference. At the moment when testing is required, the dynamic loading is paused or during its intervals. The 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 transmitted to the wall panel specimen 4 through the acoustic waveguide 73. The acoustic waves propagate in the wall panel specimen 4 and will be reflected when they encounter defects or boundaries. The echo is collected by the same acoustic waveguide 73 and transmitted back to the piezoelectric ceramic stack 71. The piezoelectric ceramic stack 71 converts the mechanical vibration back into an electrical signal, which is received and analyzed by the ultrasonic instrument.

[0034] The piezoelectric ceramic stack 71 is composed of 12 stacked PZT-5H type piezoelectric ceramic sheets, each with a diameter of 10 mm, a thickness of 1 mm, and a total height of 12 mm. The polarization direction is along the thickness direction, and the electrodes of adjacent ceramic sheets are connected in parallel with opposite directions to improve the output amplitude, with a maximum displacement output of 50 μm. The damping backing 72 at the upper end of the piezoelectric ceramic stack 71 is made of high-damping butyl rubber, 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 acoustic waveguide 73 fixed at the lower end of the piezoelectric ceramic stack 71 is made of TC4 titanium alloy, with a diameter of 10 mm and a length of 6 mm. The lower end is machined into a hemispherical focusing surface with a curvature radius of 4 mm, which facilitates the focusing and transmission of high-frequency sound waves to the surface of the wall plate specimen 4. The sound wave frequency range can be adjusted between 20 kHz and 2 MHz. The acoustic loader 7 is powered by a dedicated high-voltage power supply with an adjustable output voltage of 0-2000V. It also transmits and receives pulse signals through an ultrasonic instrument. The ultrasonic instrument is powered by 220V AC and has a built-in signal amplifier and filter. The amplification factor can be adjusted between 1000 and 10000 times, and the filter center frequency is 5-20MHz.

[0035] Example 3: Please see Figures 6-7The lower end of the probe rod 542 is fixedly equipped with a matching couplant release ring 6, and the acoustic waveguide 73 extends to the bottom surface of the couplant release ring 6. The couplant release ring 6 can actively release couplant during the test. On the one hand, it can prevent the wall panel specimen 4 from being worn during the test. On the other hand, the oil film formed can effectively conduct the excitation acoustic wave generated by the acoustic loader 7.

[0036] The coupling agent release ring 6 includes an oil storage ring 61. 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. When a static load is applied, the flexible lip seal 64 is squeezed after contacting the wall plate specimen 4 and a gap is formed between it and the probe rod 542. The internal pressure causes the porous polymer release layer 63 to slowly release the coupling agent and form an oil film on the surface of the wall plate specimen 4.

[0037] The oil reservoir ring 61 is precision machined from stainless steel, with an inner diameter of 15mm, an outer diameter of 25mm, and a height of 8mm. The internal oil reservoir has a volume of approximately 3mL. The upper sealing cap 65 is made of polytetrafluoroethylene (PTFE) and connects to the oil reservoir ring 61 via an M16 thread. A fluororubber sealing gasket is installed at the thread to ensure no leakage of the coupling agent. At the lower end of the oil reservoir ring 61, a microporous sintered metal filter 62, a porous polymer release layer 63, and a flexible lip-shaped sealing ring 64 are sequentially installed to work together to achieve the slow release and uniform distribution of the coupling agent. Among them, the microporous sintered metal filter 62 is made of TC4 titanium alloy with a thickness of 1.5mm and a pore size of 5-10μm, which plays the role of filtering impurities and buffering the flow rate of the coupling agent; the porous polymer release layer 63 is made of polyvinyl alcohol formaldehyde foam with a thickness of 2mm and a pore size of 10-20μm, which has good liquid retention and can control the release rate of the coupling agent at 0.05-0.1mL / min; the flexible lip seal 64 is made of fluororubber with a Shore hardness of 55A, an inner diameter of 12mm, an outer diameter of 28mm, and a lip angle of 45°. When the load curved transfer plate 55 contacts the wall plate specimen 4, the lip seal is squeezed and deformed, forming a sealing cavity with the wall plate surface. The internal pressure is used to cause the coupling agent to slowly seep out, forming a uniform oil film with a thickness of 50-100μm. The coupling agent used is a glycerol-based coupling agent with a viscosity of 50-100mPa·s, which has both good sound wave conduction and anti-wear performance.

[0038] It should be noted that this device uses a PLC controller as its core, specifically an S7-1200 model. The controller achieves coordinated control of all components through analog output modules, digital input / output modules, and communication modules. The PLC controller connects to the electric field generator via an RS485 communication interface, outputting a 0-10V control signal to adjust the electric field strength. It generates an adjustable PWM signal of 50-500Hz via a pulse output module to control the drive circuit of the electromagnetic coil 546, enabling precise control of the reciprocating extension frequency and amplitude of the probe rod 542. Through the communication interface, it links with an ultrasonic instrument to control the timing of ultrasonic pulse emission. Typically, the pulse is emitted at the moment when the probe rod 542 is at its maximum extension and stably contacts the wall plate specimen 4, avoiding vibration interference. The echo signal is processed by the ultrasonic instrument and transmitted to the data acquisition card for analysis and processing by the host computer software.

[0039] Working principle: First, the wall panel specimen 4 is installed and fixed: the wall panel specimen 4 to be tested is slid into the side slot 32 of the boundary fixture 3 along the guide slide 33. The external hydraulic oil pump is started, and hydraulic oil is injected into the U-shaped flow channel 35 inside the mounting base plate 31 through the hydraulic oil pipe 36. The pressure generated by the hydraulic oil squeezes the hydraulic pistons 37 on both sides. The hydraulic pistons 37 push the flexible clamping plate 34 towards the wall panel specimen 4 through the synchronizing rod 38. If the wall panel specimen 4 is not centered or there are differences in size, the flexible clamping plate 34 on one side will contact the specimen first and then cannot continue to move. The hydraulic pressure will actively act on the hydraulic piston 37 on the other side, pushing the flexible clamping plate 34 on the other side to continue to move until it contacts the specimen, thus achieving uniform clamping force on both sides. The electric field generator is then activated to apply an electric field of a specific intensity to the electrorheological fluid inside the flexible clamping plate 34. By adjusting the electric field intensity, the viscosity of the electrorheological fluid is changed, thereby adjusting the clamping force and accurately simulating the connection strength of the aircraft panel under actual working conditions. The flexible capsule fits flexibly with the surface of the specimen, avoiding damage to the specimen during the clamping process.

[0040] Next, the load testing assembly 5 is activated to apply multi-field coupled loads: First, the hydraulic rod 52 is controlled to extend synchronously, pushing the connecting platform 53, load transfer rod 54, and load curved transfer plate 55 downwards until the load curved transfer plate 55 makes stable contact with the surface of the wall panel specimen 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, which generates a periodically changing magnetic field, producing alternating attraction and repulsion forces on the magnetic guide rod 543. Under the reset action of the tension spring 545, the magnetic guide rod 543 drives the probe rod 542 to reciprocate along the hollow sleeve 541. The probe rod 542 passes through the perforation 56 of the load curved transfer plate 55, applying a dynamic vibration load to the wall panel specimen 4 at a specific frequency of 50-500Hz to simulate the vibration environment during flight. During this process, the electromagnetic coil 546 also acts as a sensing coil. According to Faraday's law of electromagnetic induction, when the probe rod 542 drives the magnetic guide rod 543 to move, a voltage will be induced in the coil. The amplitude of the induced voltage is proportional to the speed of movement. By integrating the induced signal, the dynamic displacement amplitude of the probe rod 542 can be accurately calculated. At the same time, the contact state between the probe rod 542 and the wall panel specimen 4 is monitored. If the induced signal shows a violent jump or high-frequency spike, it is immediately determined to be "contact instability" and a prompt is issued.

[0041] Subsequently, the acoustic loader 7 is activated to conduct acoustic fatigue testing: the piezoelectric ceramic stack 71 generates high-frequency vibration under the drive of a high-voltage power supply, forming a high-frequency acoustic excitation. The acoustic wave is focused by the focusing surface of the acoustic waveguide 73 and then transmitted to the surface of the wall panel specimen 4, realizing the application of acoustic load and simulating the fatigue effect of engine acoustic waves on the wall panel during aircraft flight. The damping backing 72 effectively blocks the propagation of acoustic waves into the hollow sleeve 541, avoiding interference with the induction signal of the electromagnetic coil 546, realizing the coordinated application of vibration load and acoustic load, and achieving multi-field coupled loading. During the load application process, the couplant release ring 6 simultaneously releases the couplant: after the flexible lip seal ring 64 contacts the wall plate specimen 4, it is squeezed and deformed, forming a tiny gap with the probe rod 542. Under the action of internal pressure, the couplant 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, and finally seeps out to the surface of the wall plate specimen 4 to form a uniform oil film. This not only avoids wear on the specimen during reciprocating vibration, but also ensures that the sound waves generated by the acoustic loader 7 can be transmitted efficiently.

[0042] When defect detection is required on the wall panel specimen 4, the PLC controller pauses the dynamic vibration loading or, during a stable period of vibration interval, sends a control signal to the ultrasonic instrument. The ultrasonic instrument emits a 0-2000V high-voltage pulse to the piezoelectric ceramic stack 71, which generates high-frequency ultrasonic vibration. This vibration is focused and transmitted to the interior of the wall panel specimen 4 via the acoustic waveguide 73. When the sound wave propagates inside the specimen, it is reflected if it encounters a defect or boundary. The reflected echo is collected by the acoustic waveguide 73 and transmitted back to the piezoelectric ceramic stack 71. The piezoelectric ceramic stack 71 converts the mechanical vibration into an electrical signal. This signal is amplified and filtered by the ultrasonic instrument before being transmitted to the host computer. The software analyzes the amplitude, phase, and other parameters of the echo signal to accurately identify the location and size of defects inside the wall panel specimen 4, thus completing a comprehensive assessment of strength and defects.

[0043] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. An aircraft fuselage panel strength test apparatus, characterized by: The application relates to a wallboard test device, which comprises a detection table (1) with a boundary clamp (3) fixedly arranged at the upper end of the detection table (1), a wallboard test piece (4) clamped on the boundary clamp (3), a fixed back plate (2) fixedly arranged at the rear end of the detection table (1), and a load test assembly (5) fixedly arranged at the lower end of the fixed back plate (2) and located above the wallboard test piece (4). The load test assembly (5) comprises an arc top plate (51) fixedly arranged at the lower end of the fixed back plate (2), a plurality of annularly arranged hydraulic rods (52) fixedly arranged at the lower end of the arc top plate (51), a connecting table (53) fixedly arranged at the output end of the hydraulic rods (52), a load transmission rod (54) fixedly arranged 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 arranged at one end of the load transmission rod (54) close to the wallboard test piece (4).

2. A device for testing the strength of an aircraft fuselage panel according to claim 1, characterized in that: The boundary clamp (3) comprises a mounting bottom plate (31), side insertion grooves (32) are formed at the left and right ends of the mounting bottom plate (31), a pair of symmetrically distributed flexible clamping plates (34) are slidably arranged in the side insertion grooves (32), and a pair of guide sliding channels (33) corresponding to the side insertion grooves (32) are fixedly arranged at the front end of the mounting bottom plate (31).

3. An aircraft fuselage wall panel strength test apparatus as defined in claim 2, wherein: A pair of U-shaped flow channels (35) corresponding to the side insertion grooves (32) are formed in the mounting bottom plate (31), the U-shaped flow channels (35) are connected with a hydraulic oil pump through hydraulic oil pipes (36), interference-fitted hydraulic pistons (37) are slidably arranged at the left and right side openings of the U-shaped flow channels (35), and synchronous rods (38) are fixedly arranged between the hydraulic pistons (37) and the flexible clamping plates (34).

4. A device for testing the strength of an aircraft fuselage panel according to claim 3, characterized in that: The flexible clamping plates (34) are hollow elastic bag-shaped structures, the inner sides of the flexible clamping plates (34) are filled with electro-rheological fluid, and the flexible clamping plates (34) are electrically connected with an electric field generator.

5. A device for testing the strength of an aircraft fuselage panel according to claim 4, characterised in that: The load transmission rod (54) comprises a hollow sleeve (541), a matching detection rod (542) is slidably arranged in the hollow sleeve (541), and a perforation (56) corresponding to the detection rod (542) is formed at the lower end of the load curved surface transmission plate (55).

6. A device for testing the strength of an aircraft fuselage panel according to claim 5, characterized in that: A magnetic guide rod (543) is fixedly arranged at the upper end of the detection rod (542), an electromagnetic coil (546) corresponding to the magnetic guide rod (543) is fixedly arranged in the hollow sleeve (541), a connecting plate (544) is fixedly arranged at the upper end of the magnetic guide rod (543), and a tension spring (545) is fixedly arranged between the connecting plate (544) and the top wall of the hollow sleeve (541).

7. A device for testing the strength of an aircraft fuselage panel according to claim 6, characterised in that: A sound generating groove is formed at the lower end of the detection rod (542), and a sound wave loader (7) is arranged in the sound generating groove.

8. A device for testing the strength of an aircraft fuselage panel according to claim 7, characterized in that: The sound wave loader (7) comprises a piezoelectric ceramic stack (71), a damping backing (72) is fixedly arranged between the upper end of the piezoelectric ceramic stack (71) and the top wall of the sound generating groove, and a sound wave waveguide (73) is fixedly arranged at the lower end of the piezoelectric ceramic stack (71).

9. A device for testing the strength of an aircraft fuselage panel according to claim 8, characterised in that: A matching coupling agent releasing ring (6) is fixedly arranged at the lower end of the detection rod (542), and the sound wave waveguide (73) extends to the bottom surface of the coupling agent releasing ring (6).

10. A device for testing the strength of an aircraft fuselage panel according to claim 9, characterized in that: The coupling agent release ring (6) comprises an oil storage ring (61), the lower end of which is sequentially provided with a microporous sintered metal filter screen (62), a porous polymer release layer (63) and a flexible lip-shaped sealing ring (64), and the upper end of the oil storage ring (61) is provided with a sealing cover (65).

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