Ultrasonic resonance multi-axial tension-compression fatigue test device

Abstract

The application discloses an ultrasonic resonance multiaxial tension-compression fatigue experimental device, which is improved on the basis of an existing biaxial device and is a set of ultrahigh-frequency biaxial resonance experimental device. The device can realize orthogonal resonance type specimen long-life multiaxial cycle fatigue test through the cooperation of two horizontal worktables. The device comprises an orthogonal resonance type specimen and two horizontal worktables. Two adjacent ends of the orthogonal resonance type specimen are arranged on the two horizontal worktables through amplitude rods. The orthogonal resonance type specimen is a cross-shaped structure of 'complete symmetry orthogonal resonance type'. Two adjacent force arms and a central part are connected through a curved surface. The central projection of the orthogonal resonance type specimen is a conical platform. The horizontal worktable comprises a moving mechanism composed of a bottom plate, a sliding block and a slide, an upper plate provided with a vertical arched circular plate and a transducer. The moving mechanism is arranged between the upper plate and the bottom plate. The transducer is installed on the vertical arched circular plate through a flange. The amplitude rod is connected to the transducer.

Description

Technical Field

[0001] This invention relates to the field of material fatigue testing technology, and more specifically, to an ultrasonic resonance multiaxial tensile and compressive fatigue testing device. Background Technology

[0002] Fatigue failure is the primary failure mode of components or structures under alternating loads. For example, fatigue failure is the main failure mode of components and structures such as vehicles, aircraft, gears, turbine blades, and springs. In actual engineering accidents, fatigue-related accidents account for up to 80%. Therefore, the study of material fatigue properties has always been a research topic of concern for the engineering community both domestically and internationally.

[0003] In aerospace, nuclear industry, and machinery, some structural components need to withstand high-frequency vibration loads during operation. Especially when other loads are present, the resulting combined damage can significantly accelerate the failure of structural components. Therefore, research on the fatigue life of high-speed rotating structural components, both domestically and internationally, places particular emphasis on ultra-high frequency fatigue life. Furthermore, with the development and application of new materials, there are higher requirements for material reliability and stability during service, making research on long lifespan and more complex stress states especially important.

[0004] Multiaxial fatigue refers to fatigue occurring under multiaxial stress states, where the directions and amplitudes of two or three principal stresses (principal strains) change over time. Many components operate under complex multiaxial stress states in real-world environments such as aerospace, nuclear power plants, chemical engineering, and vehicle transportation. However, current research on multiaxial fatigue theory is not as comprehensive and in-depth as that on uniaxial fatigue theory, especially regarding ultra-high cycle life multiaxial fatigue. Uniaxial research results often cannot fully explain the problems under actual operating conditions, making biaxial experimental research crucial. However, with existing equipment and methods, biaxial experiments cannot be combined with long-life studies, primarily due to the lack of a stable and independent experimental method.

[0005] In multiaxial testing, the phase difference and frequency of the load both affect the prediction of the material's long life. Currently, there are two common methods: 1. Conduct long life tests using only a single independent load; 2. Use a biaxial tensile testing machine to change the phase difference and frequency parameters of the load, thereby observing the experimental results of different phases. The current approach involves a trade-off between these two conditions. Considering the complex phase and frequency effects requires sacrificing experimental time (often several months for a single specimen in long life prediction), while saving experimental time means not considering the effects of complex loads. Existing biaxial equipment is either a cross-shaped low-frequency tensile testing machine or a high-frequency resonant machine under a single load. Trade-offs are often required in experimental design, resulting in a severe lack of data for long-life multiaxial cyclic fatigue testing. Therefore, to promote further development in the field of fatigue in my country and to address the actual working conditions of engineering materials and components, designing a testing device for high-speed multiaxial fatigue to achieve long-life multiaxial cyclic fatigue testing has become an inevitable requirement. Summary of the Invention

[0006] The purpose of this invention is to design an ultrasonic resonance multiaxial tensile and compressive fatigue testing device. Based on the existing biaxial equipment, an improvement is made to obtain an ultra-high cycle biaxial resonance testing device. Through the cooperation of two horizontal worktables, long-life multiaxial cyclic fatigue testing of orthogonal resonance specimens can be achieved.

[0007] The present invention is achieved through the following technical solution: an ultrasonic resonance multiaxial tensile and compressive fatigue test device, comprising an orthogonal resonance specimen and two horizontal worktables, wherein the two adjacent ends of the orthogonal resonance specimen are respectively set on the two horizontal worktables by means of amplitude transformers.

[0008] To further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specifically adopted: the orthogonal resonance specimen is a "completely symmetrical orthogonal resonance" cross-shaped structure, with two adjacent lever arms and the central part connected by a curved surface, and the central projection of the orthogonal resonance specimen is a conical platform.

[0009] To further improve the ultrasonic resonance multiaxial tensile-compression fatigue testing device described in this invention, the following structure is specifically adopted: the design dimensions of the orthogonal resonance specimen under tensile-compression mode conditions at a frequency of 20kHz are as follows: its thickness is 2.9mm, its total length is 28.93mm, and the lever arm width outside the curved section is 10.81mm. The cross-section of the four centrally symmetrical curved surfaces is an elliptical arc with a major semi-axis of 16.43mm and a minor semi-axis of 9.51mm.

[0010] To further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device described in this invention, the following structure is specifically adopted: the center of the orthogonal resonance specimen is a large conical platform with a projected radius of 12.89m and a center thickness of 0.3mm.

[0011] To further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device described in this invention, the following structure is specifically adopted: the orthogonal resonance specimen resonates at the same frequency at a specified test frequency of 20kHz, and the mode it is in is the tensile and compressive mode.

[0012] To further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specifically adopted: the orthogonal resonance specimen and the amplitude transformer are connected by a threaded structure.

[0013] To further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specifically adopted: the horizontal worktable includes a base plate, a sliding mechanism consisting of a slider and a slide rail, an upper plate with a vertical arched circular plate above it, and a transducer. The sliding mechanism is located between the upper plate and the base plate. The transducer is mounted on the vertical arched circular plate through a flange. The amplitude transformer is connected to the transducer.

[0014] To further improve the ultrasonic resonance multiaxial tensile and compressive fatigue testing device of the present invention, the following structure is specifically adopted: the slide is fixed on the base plate and the slider is fixed on the upper plate.

[0015] To further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device described in this invention, the following structure is specifically adopted: orthogonal biaxial loading can be achieved simply by using the threaded structure between two orthogonal resonance specimens and the amplitude transformer.

[0016] The most common biaxial stretching tests on the market achieve biaxial stretching or compression by moving the four clamping ends in two orthogonal directions.

[0017] Experimental verification shows that this invention achieves its experimental purpose through biaxial resonance. Signals are transmitted from a host computer, and then converted into mechanical signals by piezoelectric ceramics. This resonance allows the orthogonal resonant specimen to undergo tensile-compressive mode experiments at a frequency of 20 kHz. The resonant method achieves biaxial tensile-compressive stress through only one connection point in each of the two orthogonal directions: stress waves are transmitted from the connection points to the free ends in their respective directions, ensuring that the peak values ​​of the two stress waves intersect precisely at the center of the orthogonal resonant specimen. The stress wave loading amplitude and bidirectional phase difference are controlled by the host computer signal. This represents a completely different driving force and loading method.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects: The horizontal worktable described in this invention differs from traditional biaxial tensile tests. It can reduce the test time while considering phase, and limit the test data to the ultra-high frequency range. It can achieve multi-direction multi-load loading through independent control, and can realize resonant mode tests such as high-frequency tension and compression.

[0019] The orthogonal resonance specimen of this invention adopts a completely symmetrical design, which makes the stress distribution more uniform in the experiment and ensures that the fatigue fracture of the orthogonal resonance specimen occurs at the intersection of the cross centers, thus reducing the research scope. Its loading method is multi-load loading, which changes the traditional single-load loading biaxial model experiment method. It increases the radius of the central groove, making the stress distribution more uniform and preventing sudden stress stratification.

[0020] This invention enables the horizontal worktable to move freely on a horizontal plane, which is suitable for loading biaxial specimens of different sizes in experiments.

[0021] This invention can adapt to more varied experimental environments and allows for non-contact observation during experiments.

[0022] This invention simplifies the loading and unloading of biaxial specimens during dual-load loading experiments.

[0023] The horizontal fixing device (slider, slide rail, vertical arched circular plate) of the horizontal worktable of the present invention can realize the joint operation of multiple transducers on the same plane, thereby better carrying out multi-axis resonance experiments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the orthogonal resonance specimen structure described in this invention (excluding the threaded section).

[0025] Figure 2 This is a schematic diagram of the horizontal worktable structure described in this invention.

[0026] Figure 3 This is a front view of a single horizontal worktable.

[0027] Figure 4 This is a schematic diagram of the installation structure for conducting long-life multiaxial cyclic fatigue resonance experiments according to the present invention.

[0028] Figure 5 This is a schematic diagram of the orthogonal resonance specimen of the present invention connected to one of the horizontal worktables via an amplitude transformer.

[0029] Figure 6 This is a schematic diagram illustrating the loading and unloading of test specimens for the experimental setup.

[0030] Among them, 1-orthogonal resonance specimen, 2-slider, 3-slide rail, 4-vertical arched circular plate, 5-flange, 6-transducer, 7-amplifier rod, 8-bent arc surface, 9-bolt. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0033] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms, etc., is based on the orientation or positional relationship shown in the drawings and is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "setting," "layout," and "fixing," etc., should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections. The specific means used are not limited to conventional mechanical connection methods such as screwing, interference fit, riveting, and threaded auxiliary connections. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] It is worth noting that in this application, when certain well-known or conventional technical means in the field are required, the applicant may not have specifically described what kind of technical means the well-known or / and conventional technical means are in the text. However, the fact that the technical means are not specifically disclosed in the text does not mean that the technical solution of this application is unclear.

[0038] Definitions: Threaded auxiliary parts refer to any kind of connecting parts used to connect two structures, including bolts, screws, and screws. In the following embodiments, bolts are preferred as threaded auxiliary parts.

[0039] Example 1: like Figures 1-6 As shown, the ultrasonic resonance multiaxial tensile and compressive fatigue test device is an improved version of the existing biaxial equipment, resulting in an ultra-high cycle biaxial resonance test device. It includes an orthogonal resonance specimen 1 and two horizontal worktables. The two adjacent ends of the orthogonal resonance specimen 1 are respectively set on the two horizontal worktables through the amplitude transformer 7.

[0040] As a preferred setup, existing biaxial equipment is either a cross-shaped low-frequency tensile machine or a high-frequency resonance machine under single load. In experimental design, trade-offs are often necessary, resulting in a severe lack of data for long-life multiaxial cyclic fatigue tests. Based on this, this embodiment provides an ultra-high cycle biaxial resonance experimental device, which consists of an orthogonal resonance specimen 1, an amplitude transformer 7, and two horizontal worktables. The orthogonal resonance specimen 1 is connected to the two horizontal worktables through the amplitude transformer 7. The cooperation of the two horizontal worktables enables long-life multiaxial cyclic fatigue testing of the orthogonal resonance specimen.

[0041] Example 2: This embodiment is a further optimization based on the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Figures 1-6As shown, to further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structural configuration is specifically adopted: the orthogonal resonance specimen 1 is a "completely symmetrical orthogonal resonance" cross-shaped structure, with two adjacent lever arms and the central part connected by a curved surface 8. The central projection of the orthogonal resonance specimen 1 is a conical platform. The orthogonal resonance specimen 1 adopts a completely symmetrical design, which makes the stress distribution more uniform in the experiment, ensuring that the fatigue fracture of the orthogonal resonance specimen occurs at the intersection of the cross centers, thus reducing the research scope. Its loading method is multi-load loading, changing the traditional single-load loading biaxial model test method. The radius of the central groove is increased, making the stress distribution more uniform and preventing sudden stress stratification.

[0042] Example 3: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Figures 1-6 As shown, to further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specifically adopted: the design dimensions of the orthogonal resonance specimen 1 under tensile and compressive mode conditions at a frequency of 20kHz are: its thickness is 2.9mm, its total length is 28.93mm, the lever arm width outside the curved part is 10.81mm, and the cross-section of the four centrally symmetrical curved surfaces 8 is an elliptical arc with a major semi-axis of 16.43mm and a minor semi-axis of 9.51mm.

[0043] Example 4: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Figures 1-6 As shown, in order to better realize the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specially adopted: the center of the orthogonal resonance specimen 1 is a large conical platform with a projection radius of 12.89m and a center thickness of 0.3mm.

[0044] Example 5: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Figures 1-6 As shown, in order to better realize the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specially adopted: the orthogonal resonance specimen 1 resonates at the same frequency at the specified experimental frequency of 20kHz, and the mode it is in is the tensile and compressive mode.

[0045] Example 6: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Figures 1-6As shown, to further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specifically adopted: the orthogonal resonance specimen 1 and the amplitude transformer 7 are connected by a threaded structure. Preferably, an external thread section adapted to the internal thread of the amplitude transformer 7 is extended at the lever arm end where the orthogonal resonance specimen 1 and the amplitude transformer 7 are connected. The threaded structure allows the orthogonal resonance specimen 1 to fit tightly with the amplitude transformer 7 and will not undergo relative displacement under high-frequency vibration.

[0046] Example 7: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Figures 1-6 As shown, to further improve the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specifically adopted: the horizontal worktable includes a base plate, a sliding mechanism consisting of a slider 2 and a slide rail 3, an upper plate with a vertical arched circular plate 4 above it, and a transducer 6. The sliding mechanism is set between the upper plate and the base plate. The transducer 6 is mounted on the vertical arched circular plate 4 through a flange 5. The amplitude rod 7 is connected to the transducer 6.

[0047] Example 8: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Figures 1-6 As shown, in order to better realize the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specifically adopted: the slide 3 is fixed on the base plate and the slider 2 is fixed on the upper plate.

[0048] Example 9: This embodiment is a further optimization based on any of the above embodiments. The similarities with the aforementioned technical solutions will not be repeated here. Figures 1-6 As shown, in order to better realize the ultrasonic resonance multiaxial tensile and compressive fatigue test device of the present invention, the following structure is specially adopted: orthogonal biaxial force loading can be achieved by only the threaded structure between the two orthogonal resonance specimens 1 and the amplitude rod 7.

[0049] Example 10: This embodiment is a further optimization based on any of the above embodiments, such as... Figures 1-6 As shown, existing biaxial equipment is either a cross-shaped low-frequency tensile machine or a high-frequency resonance machine under single load. In experimental design, trade-offs are often required, which results in a severe lack of data for long-life multiaxial cyclic fatigue tests. Based on this, this embodiment provides a set of ultra-high cycle biaxial resonance test equipment (ultrasonic resonance multiaxial tensile and compressive fatigue test device), which consists of an orthogonal resonance specimen 1, an amplitude transformer 7, and two horizontal worktables.

[0050] Because the design of multiaxial specimens needs to consider stress concentration and stress distribution, and resonance needs to be achieved at the frequency of the experimental modes in ultra-high frequency experiments, the design of the size and shape of the orthogonal resonance specimen 1 requires high precision. This embodiment provides a specimen model of the material under test (orthogonal resonance specimen 1). Taking the tensile-compression mode design of aluminum alloy at 20kHz as an example, the orthogonal resonance specimen 1 is a 2.9mm thick "completely symmetrical orthogonal resonance" thin sheet structure. Two adjacent lever arms and the central part are connected by curved surfaces 8. The total length of the orthogonal resonance specimen 1 is 28.93mm, and the width of the lever arms is 10.81mm. The cross-section of the four centrally symmetrical curved surfaces 8 is an elliptical arc with a major semi-axis of 16.43mm and a minor semi-axis of 9.51mm. At the specified experimental frequency of 20kHz, the orthogonal resonance specimen 1 resonates at the same frequency, exhibiting the tensile-compression mode. The ends of the orthogonal resonance specimen 1 connected to the amplitude transformer 7 are all machined with the same thread (extending and adding threaded sections), allowing for a tight fit with the amplitude transformer 7 and preventing relative slippage under high-frequency vibration. The elliptical arc sides of the orthogonal resonance specimen 1 are all chamfered to prevent stress concentration outside the test section. The center of the orthogonal resonance specimen 1 is a large conical platform with a projected radius of 12.89m and a center thickness of 0.3mm. This design ensures maximum stress at the center of the specimen, leading to fatigue fracture. Because of the large radius and smooth transition, no stress gradient occurs. Observation of the test section allows for research in the field of ultra-high frequency multiaxial fatigue. The orthogonal resonance specimen... Figure 1 As shown.

[0051] To ensure that the orthogonal resonance specimen 1 and the transducer (using an ultrasonic transducer head) 6 resonate at the same frequency, forming a unified resonance system, the following is given: Figure 2 The horizontal working platform shown consists of a base plate, a sliding mechanism composed of sliders 2 and slide rails 3, an upper plate with a vertical arched circular plate 4, and a transducer 6 using an ultrasonic transducer head. The sliding mechanism is located between the upper plate and the base plate. The transducer 6 is mounted on the vertical arched circular plate 4 via flanges 5. An amplitude transformer 7 is connected to the transducer 6, allowing it to move in a planar coordinate system via four sliders 2 at its lower end. Bolts 9 connect the vertical arched circular plate 4 and the flanges 5, fixing the transducer 6 and constraining the vertical and angular degrees of freedom without affecting the lateral displacement amplitude. By connecting the horizontal working platform and the orthogonal resonance specimen 1, biaxial resonance is achieved. Figure 4 As shown, a long-life multiaxial cyclic fatigue resonance experiment was conducted.

[0052] Combination Figure 3 , Figure 5and Figure 6 As shown, the loading and unloading instructions are as follows: Figure 5 and Figure 6 The arrows in the text represent the direction of rotation: 1. First, fix a horizontal worktable on the optical plane table. By rotating one end of the threaded section of the orthogonal resonance specimen 1, make the lever arm of the orthogonal resonance specimen 1 tightly connected to the amplitude transformer 7 (e.g., Figure 5 (As shown).

[0053] 2. Place another horizontal worktable on the other threaded section side of the orthogonal resonance specimen 1. Adjust the slider 2 to make the amplitude transformer 7 contact the threaded section. Then rotate the bolt 9 on the flange 5 to allow the transducer 6 to rotate. Then rotate the transducer 6 to make the orthogonal resonance specimen 1 and the amplitude transformer 7 tightly connected (e.g., Figure 3 and 6 (As shown).

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention are within the protection scope of the present invention.

Claims

1. An ultrasonic resonance multiaxial tensile-compressive fatigue testing apparatus, characterized in that: The test includes an orthogonal resonance specimen (1) and two horizontal worktables. The two adjacent ends of the orthogonal resonance specimen (1) are respectively set on the two horizontal worktables by amplitude transformers (7). The orthogonal resonance specimen (1) is a "completely symmetrical orthogonal resonance" cross-shaped structure. The two adjacent lever arms and the center part are connected by a curved surface (8). The center projection of the orthogonal resonance specimen (1) is a conical platform. The design dimensions of the orthogonal resonance specimen (1) under the tension-compression mode at a frequency of 20kHz are: its thickness is 2.9mm and its total length is 28.93mm. The lever arm width outside the curved part is 10.81 mm, and the cross-section of the four centrally symmetrical curved surfaces (8) is an elliptical arc with a major semi-axis of 16.43 mm and a minor semi-axis of 9.51 mm; the orthogonal resonance specimen (1) resonates at the same frequency at the specified experimental frequency of 20 kHz, and the mode is the tension-compression mode; the orthogonal resonance specimen (1) and the amplitude rod (7) are connected by a threaded structure, and the orthogonal biaxial loading can be achieved by only two threaded structures between the orthogonal resonance specimen (1) and the amplitude rod (7).

2. The ultrasonic resonance multiaxial tensile-compressive fatigue testing apparatus according to claim 1, characterized in that: The center of the orthogonal resonance specimen (1) is a conical platform with a projection radius of 12.89m and a center thickness of 0.3mm.

3. The ultrasonic resonance multiaxial tensile-compressive fatigue testing apparatus according to claim 1 or 2, characterized in that: The horizontal worktable includes a base plate, a sliding mechanism consisting of a slider (2) and a slide rail (3), an upper plate with a vertical arched circular plate (4) on top, and a transducer (6). The sliding mechanism is located between the upper plate and the base plate. The transducer (6) is mounted on the vertical arched circular plate (4) via a flange (5). The amplitude rod (7) is connected to the transducer (6).

4. The ultrasonic resonance multiaxial tensile-compressive fatigue testing apparatus according to claim 3, characterized in that: The slide (3) is fixed on the base plate, and the slider (2) is fixed on the top plate.

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