Rubber diaphragm super high cycle fatigue equivalent simulation test method and system under gas-liquid pressure difference
Patent Information
- Application Number
- CN202611459304.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-20
- Publication Date
- 2026-10-30
AI Technical Summary
[0006]本发明提出一种气液压差下橡胶隔膜超高周疲劳等效模拟测试方法及系统，解决了现有橡胶隔膜疲劳测试中直接采用气压、液压或气液压差循环加载时存在的密封要求高、加载控制复杂、加载频率受限、长周期测试效率低以及试验重复性不易保证等问题
本发明提出的一种气液压差下橡胶隔膜超高周疲劳等效模拟测试方法及系统，通过建立橡胶隔膜在实际气液压差载荷作用下的有限元分析模型，获得其变形、应变响应，并据此确定轴向循环机械载荷参数，能够将不便长期稳定施加的气液压差循环载荷转化为易于控制的机械循环载荷，无需依赖复杂的气压或液压循环加载系统，从而大幅降低了对密封系统、压力控制系统和流体循环系统的要求；其次，通过对橡胶隔膜试验件边缘固定、设置通孔并采用第一夹片、第二夹片及刚性加载杆施加轴向循环机械载荷，加载形式简单，便于控制加载位移、幅值、频率、波形、循环次数等参数，显著提高了超高周疲劳测试的可实施性和测试效率；最后，通过采集机械载荷作用下的应变、循环次数或失效状态，能够在保证机械加载响应与实际气液压差载荷响应满足预设等效条件的前提下，获得橡胶隔膜在气液压差服役条件下的疲劳性能，解决了传统流体加载方式难以兼顾加载稳定性、测试效率和工况等效性的问题，适用于碗状或膜片状橡胶隔膜的超高周疲劳寿命测试、失效分析和结构优化。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of rubber diaphragm fatigue performance testing technology, and in particular to a method and system for equivalent simulation testing of ultra-high cycle fatigue of rubber diaphragms under pneumatic-hydraulic differential. Background Technology
[0002] Rubber diaphragms are a type of elastic element commonly used for sealing, isolation, pressure transmission, and flexibility compensation. They are widely used in valves, pumps, pressure regulators, actuators, and other equipment involving the isolation of gas or liquid media. In actual service, rubber diaphragms are typically installed within fixed boundaries, with their sides subjected to gas pressure, liquid pressure, or gas-liquid pressure differential. With long-term operation, the rubber diaphragm undergoes repeated deformation under cyclic differential pressure loads, potentially leading to fatigue damage, resulting in decreased sealing performance or even failure.
[0003] For cup-shaped or diaphragm-shaped rubber diaphragms, the stress and deformation under service conditions typically exhibit significant nonlinear characteristics. On the one hand, rubber materials themselves possess mechanical properties such as large deformation, hyperelasticity, and viscoelasticity; on the other hand, the diaphragm structure undergoes significant flexural deformation under pressure differential, and high strain concentration easily forms in localized areas. Therefore, to evaluate the reliability of rubber diaphragms under long-term service conditions, fatigue performance testing is necessary, especially under high-cycle or ultra-high-cycle service conditions, to obtain their fatigue response and life characteristics under near-actual differential pressure loads.
[0004] Existing fatigue testing methods for rubber diaphragms typically employ pneumatic loading, hydraulic loading, or pneumatic-hydraulic differential loading to simulate the actual service environment of the diaphragm as closely as possible. However, for ultra-high cycle fatigue testing, directly using gas or liquid pressure for long-term cyclic loading has certain shortcomings. For example, pneumatic or hydraulic cyclic loading systems have high requirements for sealing performance and complex loading device structures; under high-frequency or long-cycle loading conditions, pressure control stability and response speed are difficult to guarantee; simultaneously, the gas-liquid medium loading process may be affected by factors such as pipeline volume, medium compressibility, seal leakage, temperature rise, and pressure fluctuations, resulting in low testing efficiency, poor repeatability, and long test cycles. Furthermore, if fatigue verification relies solely on actual pneumatic-hydraulic differential loading, the setup and maintenance costs of the test system are high, and it is not convenient to quickly conduct comparative tests under different load amplitudes and cyclic conditions. Especially when ultra-high cycle fatigue evaluation is required, traditional fluid loading methods often struggle to simultaneously ensure loading stability, testing efficiency, and operational equivalence.
[0005] Therefore, it is necessary to design an equivalent simulation test method and system for ultra-high cycle fatigue of rubber diaphragms under pneumatic-hydraulic differential pressure, so as to transform the pneumatic-hydraulic differential cyclic load, which is inconvenient to apply stably for a long time, into an easily controllable mechanical cyclic load while maintaining the equivalence of the key response of the rubber diaphragm with the actual pneumatic-hydraulic differential load response. This will improve the feasibility, stability and efficiency of ultra-high cycle fatigue testing of rubber diaphragms. Summary of the Invention
[0006] This invention proposes an equivalent simulation test method and system for ultra-high cycle fatigue of rubber diaphragms under pneumatic-hydraulic differential pressure, which solves the problems of high sealing requirements, complex loading control, limited loading frequency, low efficiency of long-cycle testing, and difficulty in ensuring test repeatability when directly using pneumatic, hydraulic or pneumatic-hydraulic differential pressure cyclic loading in the fatigue test of rubber diaphragms.
[0007] The technical solution of this invention is: a method for equivalent simulation testing of ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure, comprising the following steps: A finite element analysis model of the rubber diaphragm under actual pneumatic-hydraulic differential load was established to obtain the response characteristics of the rubber diaphragm under the actual pneumatic-hydraulic differential load. Rubber diaphragm test pieces are prepared based on actual service rubber diaphragms, and through holes are provided on the rubber diaphragm test pieces; The edge area of the rubber diaphragm test piece is fixed, a rigid loading rod is vertically set on one side of the rubber diaphragm test piece, and a first clamping piece and a second clamping piece are respectively set on both sides of the rubber diaphragm test piece. The first clamping piece and the second clamping piece are clamped together by a fixing piece that passes through the first clamping piece, the through hole of the rubber diaphragm test piece and the second clamping piece and is connected to the rigid loading rod. An axial cyclic mechanical load is applied to the rigid loading rod so that the response characteristics of the rubber diaphragm test specimen under mechanical loading and the response characteristics under actual pneumatic-hydraulic differential load satisfy a preset equivalent condition. The strain, number of cycles, or failure state of the rubber diaphragm test specimen under axial cyclic mechanical load are collected to obtain the fatigue performance of the rubber diaphragm under pneumatic-hydraulic differential load service conditions.
[0008] In at least one embodiment of the present invention, the response characteristics include at least one of the following: deformation state of the rubber diaphragm, displacement field, maximum principal strain, location of the critical region, and strain distribution along the critical path.
[0009] In at least one embodiment of the present invention, the preset equivalent condition includes at least one of the following conditions: The deformation response of the rubber diaphragm specimen under mechanical loading is consistent with or basically consistent with the deformation response of the rubber diaphragm under pneumatic-hydraulic differential loading. The maximum principal strain distribution of the rubber diaphragm test specimen under mechanical loading is consistent with or basically consistent with the maximum principal strain distribution of the rubber diaphragm under pneumatic-hydraulic differential loading. The location of the critical area of the rubber diaphragm test specimen under mechanical loading is the same as or basically the same as the location of the critical area of the rubber diaphragm under pneumatic-hydraulic differential load. When evaluating using the strain form of the Goodman relation, the Goodman equivalent strain of the critical area of the rubber diaphragm specimen under mechanical loading is greater than or equal to the Goodman equivalent strain of the critical area of the rubber diaphragm under pneumatic-hydraulic differential loading.
[0010] In at least one embodiment of the present invention, the axial cyclic mechanical load includes at least one of the following: load displacement, load amplitude, load upper and lower limits, load frequency, load waveform, number of cycles, and stopping condition.
[0011] In at least one embodiment of the present invention, the area on the rubber diaphragm test piece that is clamped by the first clamp and the second clamp is the non-fatigue evaluation area.
[0012] This invention also proposes an equivalent simulation test system for ultra-high cycle fatigue of rubber diaphragms under pneumatic-hydraulic differential pressure, used for testing rubber diaphragm test specimens, wherein the rubber diaphragm test specimens have through holes. The system includes: The fixing part includes two mutually fitted and bolted first fixing rings and second fixing rings; the rubber diaphragm test piece is clamped between the first fixing rings and the second fixing rings; The loading component includes a rigid loading rod vertically disposed on one side of the rubber diaphragm test piece, a first clamping piece and a second clamping piece disposed on both sides of the rubber diaphragm test piece, and a loading drive component connected to the rigid loading rod. The first clamping piece and the second clamping piece clamp the rubber diaphragm test piece by a fixing member passing through the first clamping piece, the through hole of the rubber diaphragm test piece, and the second clamping piece. The fixing member is fixedly connected to the rigid loading rod. The loading drive component is used to apply an axial cyclic mechanical load to the rigid loading rod. The loading controller is connected to the loading drive signal and is used to set the loading amplitude, upper and lower limits, loading frequency, loading waveform, loading displacement, number of cycles or stopping conditions of the loading drive; The data acquisition unit is connected to the loading drive component signal and is used to acquire the number of cycles of the loading drive component; the data acquisition unit is also used to acquire the strain and failure state of the rubber diaphragm test specimen under axial cyclic mechanical load.
[0013] In at least one embodiment of the present invention, the data acquisition unit includes a strain gauge disposed on the rubber diaphragm test specimen, a displacement sensor for measuring the loaded displacement, a cycle number recording module for detecting the cycle number of the loading drive component, and an image acquisition device for recording the failure state of the rubber diaphragm test specimen.
[0014] In at least one embodiment of the present invention, the first clamp and the second clamp both have curved surfaces that fit with the rubber diaphragm test piece, the end of the rigid loading rod is provided with a threaded hole, and the fixing member is a bolt that passes through the first clamp, the through hole of the rubber diaphragm test piece and the second clamp and is threadedly connected to the threaded hole.
[0015] In at least one embodiment of the present invention, the first fixing ring and the second fixing ring are provided with opposite annular grooves on opposite sides, and the edge area of the rubber diaphragm test piece is fitted into the annular groove.
[0016] In at least one embodiment of the present invention, the rigid loading rod is a cylindrical rod, and a sliding bearing is sleeved on the rigid loading rod. The sliding bearing is used to guide the rigid loading rod and limit the radial displacement of the rigid loading rod.
[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes an equivalent simulation test method and system for ultra-high cycle fatigue of rubber diaphragms under pneumatic-hydraulic differential load. By establishing a finite element analysis model of the rubber diaphragm under actual pneumatic-hydraulic differential load, its deformation and strain response are obtained, and the axial cyclic mechanical load parameters are determined accordingly. This transforms the pneumatic-hydraulic differential cyclic load, which is inconvenient to apply stably over a long period, into an easily controllable mechanical cyclic load, eliminating the need for complex pneumatic or hydraulic cyclic loading systems and significantly reducing the requirements for sealing, pressure control, and fluid circulation systems. Furthermore, by fixing the edge of the rubber diaphragm test piece, setting through holes, and using a first clamp, a second clamp, and a rigid loading rod to apply the axial load... The cyclic mechanical load method is simple to apply and facilitates control of parameters such as displacement, amplitude, frequency, waveform, and number of cycles, significantly improving the feasibility and efficiency of ultra-high cycle fatigue testing. Finally, by collecting strain, number of cycles, or failure state under mechanical load, the fatigue performance of rubber diaphragms under pneumatic-hydraulic differential load conditions can be obtained while ensuring that the mechanical loading response and the actual pneumatic-hydraulic differential load response meet the preset equivalent conditions. This solves the problem that traditional fluid loading methods cannot simultaneously achieve loading stability, testing efficiency, and working condition equivalence, and is suitable for ultra-high cycle fatigue life testing, failure analysis, and structural optimization of bowl-shaped or diaphragm-shaped rubber diaphragms. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the overall system structure of the present invention; Figure 2 This is a cross-sectional view of the testing device of the present invention; Figure 3 This is a schematic diagram of the structure of the rubber diaphragm test specimen of the present invention; Figure 4This is a schematic diagram of the axial cross-sectional structure of the rubber diaphragm test specimen of the present invention; Figure 5 This is a schematic diagram of the working condition of the rubber diaphragm of the present invention under actual pneumatic-hydraulic differential load. Figure 6 This is the maximum principal strain cloud diagram of the rubber diaphragm of the present invention under the action of pneumatic-hydraulic differential load; Figure 7 This is a contour plot of the maximum principal strain of the rubber diaphragm test specimen of the present invention under mechanical load.
[0019] Explanation of reference numerals in the attached figures: 1. Rubber diaphragm test piece; 2. First clamping piece; 3. Second clamping piece; 4. First fixing ring; 5. Second fixing ring; 6. Sliding bearing; 7. Rigid loading rod; 8. Fixing component; 9. Loading drive component; 10. Loading controller; 11. Data acquisition unit. Detailed Implementation
[0020] The accompanying drawings in this invention are not strictly drawn to scale, and the specific dimensions and quantity of each structure can be determined according to actual needs. The drawings described in this invention are merely structural schematic diagrams.
[0021] 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 some, not all, of the embodiments of the present invention. Based on the described 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.
[0022] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” indicate that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as “inner,” “outer,” “upper,” “lower,” “far,” “near,” “front,” and “rear” are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0023] like Figure 5As shown, under actual service conditions, the rubber diaphragm is subjected to a pneumatic load P1 and a hydraulic load P2 on both sides, respectively. Here, P1 represents the pneumatic load acting on one side of the rubber diaphragm, and P2 represents the hydraulic load acting on the other side. In one specific embodiment, P1 is maintained at 2 bar, while P2 fluctuates within the range of 2 ± 0.4 bar. The rubber diaphragm undergoes periodic deformation under the periodic changes in the pneumatic-hydraulic differential formed by these two loads, which may lead to fatigue damage.
[0024] Combination Figures 1 to 7 As shown, a method for equivalent simulation testing of ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential includes the following steps: A finite element analysis model of the rubber diaphragm under actual pneumatic-hydraulic differential load was established to obtain the response characteristics of the rubber diaphragm under this load. The actual pneumatic-hydraulic differential load includes the pneumatic load acting on one side of the rubber diaphragm and the hydraulic load acting on the other side.
[0025] A rubber diaphragm test piece 1 was prepared based on an actual service rubber diaphragm, and through holes were provided on the rubber diaphragm test piece 1; The edge area of the rubber diaphragm test piece 1 is fixed. A rigid loading rod 7 is vertically set on one side of the rubber diaphragm test piece 1. A first clamping piece 2 and a second clamping piece 3 are respectively set on both sides of the rubber diaphragm test piece 1. The first clamping piece 2 and the second clamping piece 3 are clamped together by a fixing piece 8 that passes through the first clamping piece 2, the through hole of the rubber diaphragm test piece 1 and the second clamping piece 3 and is connected to the rigid loading rod 7. The mechanical loading parameters are determined based on the response characteristics; an axial cyclic mechanical load is applied to the rigid loading rod 7 so that the response characteristics of the rubber diaphragm test piece 1 under mechanical loading and the response characteristics under actual pneumatic-hydraulic differential load satisfy the preset equivalent conditions. The strain, number of cycles, or failure state of the rubber diaphragm test specimen 1 under axial cyclic mechanical load are collected to obtain the fatigue performance of the rubber diaphragm under pneumatic-hydraulic differential load service conditions.
[0026] Rubber diaphragms have a cup-shaped or sheet-like elastic structure and are used for sealing, isolation, or pressure transmission during actual service. For example... Figure 3 and Figure 4 As shown, the rubber diaphragm includes a bowl-shaped deformation region and an edge fixing region. In actual service, the rubber diaphragm has a structure without a central through-hole. In this embodiment, to facilitate the application of loads mechanically, a rubber diaphragm test piece is prepared based on the actual service rubber diaphragm, and a through-hole is provided in the predetermined pressing area of the rubber diaphragm test piece to facilitate the mechanical connection of the rigid loading rod 7.
[0027] It should be noted that the through-hole is not a structure in the actual service rubber diaphragm, but rather a loading connection hole set on the test piece to achieve mechanical equivalent loading. During the test, the area containing this through-hole is clamped by the first clamp 2 and the second clamp 3, forming a non-fatigue evaluation area. Because this area is clamped by the clamps during cyclic loading and does not bear the main cyclic deformation, nor is it used as a fatigue damage evaluation area, the setting of the through-hole will not have a substantial impact on the main fatigue evaluation results of the rubber diaphragm.
[0028] As an alternative embodiment, the response characteristics include at least one of the deformation state, displacement field, maximum principal strain, location of the critical area, and strain distribution of the critical path of the rubber diaphragm. This ensures that the finite element analysis can comprehensively capture the key mechanical response characteristics of the rubber diaphragm under pneumatic-hydraulic differential load, providing a sufficient equivalent comparison basis for the determination of subsequent mechanical loading parameters.
[0029] As an alternative embodiment, the preset equivalent conditions include at least one of the following conditions: The deformation response of the rubber diaphragm specimen 1 under mechanical loading is consistent with or basically consistent with the deformation response of the rubber diaphragm under pneumatic-hydraulic differential loading. The maximum principal strain distribution of rubber diaphragm specimen 1 under mechanical loading is consistent with or basically consistent with the maximum principal strain distribution of rubber diaphragm under pneumatic-hydraulic differential loading. The location of the dangerous area of the rubber diaphragm test piece 1 under mechanical loading is the same as or basically the same as the location of the dangerous area of the rubber diaphragm under pneumatic-hydraulic differential load. When evaluating using the strain form of Goodman relation, the Goodman equivalent strain of the critical area of the rubber diaphragm test piece 1 under mechanical loading is greater than or equal to the Goodman equivalent strain of the critical area of the rubber diaphragm under pneumatic-hydraulic differential load. The above-mentioned equivalent adjustment limit ensures that the mechanical loading method has clear equivalence or conservatism for the actual pneumatic-hydraulic differential service conditions, and provides a flexible and quantifiable judgment basis for different equivalent evaluation paths.
[0030] As an alternative embodiment, the axial cyclic mechanical load includes at least one of the following: loading displacement, loading amplitude, loading upper and lower limits, loading frequency, loading waveform, number of cycles, and stopping conditions. This allows the mechanical loading parameters to be precisely set and adjusted based on the finite element analysis results, improving the parameter controllability of the testing process and its adaptability to different working conditions.
[0031] As an alternative embodiment, the area on the rubber diaphragm test piece 1 that is clamped by the first clamp 2 and the second clamp 3 is a non-fatigue evaluation area. The non-fatigue evaluation area is not used as the fatigue damage evaluation area of the rubber diaphragm test piece 1. The above limitation eliminates the adverse effects of structural modification of the rubber diaphragm test piece 1 (setting through holes) on the fatigue test results, and ensures that the test results can truly reflect the fatigue performance of the rubber diaphragm under actual service conditions.
[0032] This invention also proposes an equivalent simulation test system for ultra-high cycle fatigue of rubber diaphragms under pneumatic-hydraulic differential pressure, used for testing rubber diaphragm test specimen 1. The rubber diaphragm test specimen 1 has through holes. The system includes: The fixing part includes two mutually fitted and bolted first fixing rings 4 and second fixing rings 5; the rubber diaphragm test piece 1 is clamped between the first fixing rings 4 and second fixing rings 5 to simulate the installation boundary of the rubber diaphragm in an actual service device; The loading component includes a rigid loading rod 7 vertically disposed on one side of the rubber diaphragm test piece 1, a first clamping piece 2 and a second clamping piece 3 respectively disposed on both sides of the rubber diaphragm test piece 1, and a loading drive component 9 connected to the rigid loading rod 7. The first clamping piece 2 and the second clamping piece 3 clamp the rubber diaphragm test piece 1 by a fixing piece 8 passing through the first clamping piece 2, the through hole of the rubber diaphragm test piece 1, and the second clamping piece 3. The fixing piece 8 is fixedly connected to the rigid loading rod 7. The loading drive component 9 is used to apply an axial cyclic mechanical load to the rigid loading rod 7. The loading drive component 9 is a loading device capable of outputting a periodic displacement load. Specifically, at least one parameter among the first clamping piece 2 and the second clamping piece 3, the size of the pressing area, and the axial cyclic mechanical load is determined based on the results of finite element analysis.
[0033] The loading controller 10 is signal-connected to the loading drive 9 and is used to set the loading amplitude, upper and lower limits, loading frequency, loading waveform, loading displacement, number of cycles or stop conditions of the loading drive 9. The data acquisition unit 11 is connected to the loading drive 9 by signal and is used to acquire the number of cycles of the loading drive 9. The data acquisition unit 11 is also used to acquire the strain and failure state of the rubber diaphragm test specimen 1 under axial cyclic mechanical load. The system can convert the pneumatic-hydraulic differential cyclic load, which is inconvenient to apply stably for a long time, into an axial cyclic mechanical load for testing. This avoids the high requirements for sealing and pressure control stability of complex pneumatic or hydraulic cyclic loading systems. At the same time, it realizes the precise control of loading parameters and the automatic acquisition of test data, which improves the feasibility and testing efficiency of ultra-high cycle fatigue testing.
[0034] As an alternative embodiment, the data acquisition unit 11 includes strain gauges disposed on the rubber diaphragm test piece 1, a displacement sensor for measuring the loaded displacement, a cycle number recording module for detecting the cycle number of the loading drive 9, and an image acquisition device for recording the failure state of the rubber diaphragm test piece 1. The data acquisition unit 11 realizes multi-dimensional synchronous acquisition of strain, displacement, cycle number and failure state during mechanical loading, providing comprehensive and accurate test data support for the fatigue performance evaluation of the rubber diaphragm.
[0035] As an alternative embodiment, both the first clamp 2 and the second clamp 3 have curved surfaces that fit with the rubber diaphragm test piece 1. The end of the rigid loading rod 7 is provided with a threaded hole. The fixing member 8 is a bolt that passes through the first clamp 2, the through hole of the rubber diaphragm test piece 1, and the second clamp 3 and is threadedly connected to the threaded hole. The above configuration ensures good fit and reliable connection between the first clamp 2 and the second clamp 3 and the rubber diaphragm test piece 1. At the same time, the bolt connection method simplifies the assembly structure, facilitates the installation and replacement of the rubber diaphragm test piece 1, and improves the ease of operation of the testing system.
[0036] As an alternative embodiment, the first fixing ring 4 and the second fixing ring 5 are provided with opposite ring grooves on opposite sides. The edge area of the rubber diaphragm test piece 1 is fitted into the ring groove, which simulates the installation boundary conditions of the rubber diaphragm in the actual service device. At the same time, it realizes the reliable fixation of the edge of the test piece, avoids edge slippage or abnormal stress concentration during the test, and ensures the consistency between the loading boundary conditions and the actual working conditions.
[0037] As an alternative embodiment, the rigid loading rod 7 is a cylindrical rod, and a sliding bearing 6 is sleeved on the rigid loading rod 7. The sliding bearing 6 is used to guide the rigid loading rod 7 and limit the radial offset of the rigid loading rod 7, ensuring the accuracy of the axial cyclic mechanical load application direction, eliminating the interference of the radial component force on the test results, and improving the stability of cyclic loading and the repeatability of test data.
[0038] In this embodiment, the maximum principal strain is used as the main fatigue evaluation parameter in the finite element equivalent analysis. For example... Figure 6 As shown, the maximum principal strain contour maps of the rubber diaphragm at three typical locations under pneumatic-hydraulic differential load were obtained, where... Figure 6 (a) in the text represents the initial position. Figure 6 (b) in the diagram represents the state when P1 is greater than P2. Figure 6 In the diagram, (c) represents the state when P1 is less than P2. Using the maximum principal strain results under the above three states, the strain amplitude and average strain under the pneumatic-hydraulic differential load condition can be calculated.
[0039] like Figure 7As shown, a finite element model of the rubber diaphragm specimen 1 under mechanical loading was further established, and the maximum principal strain contour maps at three typical locations under mechanical loading conditions were obtained. Figure 7 (a) in the text represents the initial position. Figure 7 (b) in the diagram represents the state when the rigid loading rod 7 moves downward by 2.5 mm. Figure 7 In the diagram, (c) represents the state when the rigid loading rod 7 moves upward by 2.5 mm. Using the maximum principal strain results from the above three states, the strain amplitude and average strain under mechanical loading conditions can be calculated.
[0040] In a specific example, a modified Goodman relation based on strain form is used to perform an equivalent evaluation of the fatigue risk of the rubber diaphragm. The modified Goodman relation can be expressed as: (1); in, ε eq For equivalent change, ε a For strain amplitude, ε m For average strain, ε u This represents the ultimate strain of the rubber diaphragm material.
[0041] The strain amplitude and average strain can be calculated from the extreme values of the maximum principal strain.
[0042] (2); (3); in, ε max This represents the maximum value of the principal strain during a single cycle. ε min It represents the minimum value of the maximum principal strain during a cycle.
[0043] In this embodiment, the ultimate strain ε uThe tensile test yielded a value of 2.09333. Finite element analysis was performed to extract the maximum principal strain at each node of the rubber diaphragm finite element model. Based on equations (1) to (3), the maximum equivalent strain under mechanical load was 0.349, and under pneumatic-hydraulic differential load was 0.335. Since the maximum equivalent strain under mechanical load is greater than that under pneumatic-hydraulic differential load, the mechanical loading method in this embodiment is relatively conservative compared to the actual pneumatic-hydraulic differential loading method. Therefore, when the rubber diaphragm test piece 1 does not experience ultra-high cycle fatigue failure under the mechanical load, it can be conservatively assumed that the rubber diaphragm meets the fatigue safety requirements under the corresponding pneumatic-hydraulic differential load.
[0044] It should be noted that the above-mentioned modified Goodman relation is only an equivalent evaluation method used in this embodiment. In other embodiments, the maximum principal strain, strain energy density, fatigue damage parameters or other fatigue evaluation criteria can also be used to evaluate the mechanical load condition and the pneumatic-hydraulic differential load condition.
[0045] In this way, the present invention converts the pneumatic-hydraulic differential cyclic load, which is inconvenient to apply stably for a long period of time, into an axial cyclic mechanical load that is easy to control. This avoids the high requirements of complex pneumatic or hydraulic cyclic loading systems for sealing, pressure control stability and long-term operational reliability. At the same time, it can ensure that the mechanical loading test results are representative of actual service conditions through finite element response and equivalent strain evaluation.
[0046] The above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and are not intended to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions implemented in the present invention, and should all be covered within the scope of protection of the present invention.
Claims
1. A method for equivalent simulation testing of ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure, characterized in that, Includes the following steps: A finite element analysis model of the rubber diaphragm under actual pneumatic-hydraulic differential load was established to obtain the response characteristics of the rubber diaphragm under the actual pneumatic-hydraulic differential load. Rubber diaphragm test pieces are prepared based on actual service rubber diaphragms, and through holes are provided on the rubber diaphragm test pieces; The edge area of the rubber diaphragm test piece is fixed, a rigid loading rod is vertically set on one side of the rubber diaphragm test piece, and a first clamping piece and a second clamping piece are respectively set on both sides of the rubber diaphragm test piece. The first clamping piece and the second clamping piece are clamped together by a fixing piece that passes through the first clamping piece, the through hole of the rubber diaphragm test piece and the second clamping piece and is connected to the rigid loading rod. An axial cyclic mechanical load is applied to the rigid loading rod so that the response characteristics of the rubber diaphragm test specimen under mechanical loading and the response characteristics under actual pneumatic-hydraulic differential load satisfy a preset equivalent condition. The strain, number of cycles, or failure state of the rubber diaphragm test specimen under axial cyclic mechanical load are collected to obtain the fatigue performance of the rubber diaphragm under pneumatic-hydraulic differential load service conditions.
2. The method for equivalent simulation testing of ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure as described in claim 1, characterized in that, The response characteristics include at least one of the following: deformation state of the rubber diaphragm, displacement field, maximum principal strain, location of the critical area, and strain distribution along the critical path.
3. The equivalent simulation test method for ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure as described in claim 2, characterized in that, The preset equivalent conditions include at least one of the following conditions: The deformation response of the rubber diaphragm specimen under mechanical loading is consistent with that under pneumatic-hydraulic differential loading. The maximum principal strain distribution of the rubber diaphragm specimen under mechanical loading is consistent with the maximum principal strain distribution of the rubber diaphragm under pneumatic-hydraulic differential loading. The location of the critical area of the rubber diaphragm test specimen under mechanical loading is the same as that of the rubber diaphragm under pneumatic-hydraulic differential loading. When evaluating using the strain form of the Goodman relation, the Goodman equivalent strain of the critical area of the rubber diaphragm specimen under mechanical loading is greater than or equal to the Goodman equivalent strain of the critical area of the rubber diaphragm under pneumatic-hydraulic differential loading.
4. The equivalent simulation test method for ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure as described in claim 1, characterized in that, The axial cyclic mechanical load includes at least one of the following: load displacement, load amplitude, load upper and lower limits, load frequency, load waveform, number of cycles, and stopping condition.
5. The equivalent simulation test method for ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure as described in claim 1, characterized in that, The area on the rubber diaphragm test piece that is clamped by the first and second clamps is the non-fatigue evaluation area.
6. An equivalent simulation testing system for ultra-high cycle fatigue of rubber diaphragms under pneumatic-hydraulic differential pressure, used for testing rubber diaphragm test specimens, characterized in that, The rubber diaphragm test specimen has a through hole, and the system includes: The fixing part includes two mutually fitted and bolted first and second fixing rings; the rubber diaphragm test piece is clamped between the first and second fixing rings. The loading component includes a rigid loading rod vertically disposed on one side of the rubber diaphragm test piece, a first clamping piece and a second clamping piece respectively disposed on both sides of the rubber diaphragm test piece, and a loading drive component connected to the rigid loading rod. The first clamping piece and the second clamping piece clamp the rubber diaphragm test piece by a fixing member passing through the first clamping piece, a through hole in the rubber diaphragm test piece, and the second clamping piece. The fixing member is fixedly connected to the rigid loading rod. The loading drive component is used to apply an axial cyclic mechanical load to the rigid loading rod. The load controller is connected to the load drive signal and is used to set the load amplitude, upper and lower load limits, load frequency, load waveform, load displacement, number of cycles or stop conditions of the load drive. The data acquisition unit is connected to the loading drive component signal and is used to acquire the number of cycles of the loading drive component; the data acquisition unit is also used to acquire the strain and failure state of the rubber diaphragm test specimen under axial cyclic mechanical load.
7. The equivalent simulation test system for ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure as described in claim 6, characterized in that, The data acquisition unit includes strain gauges installed on the rubber diaphragm test specimen, displacement sensors for measuring the loaded displacement, a cycle number recording module for detecting the cycle number of the loading drive component, and an image acquisition device for recording the failure state of the rubber diaphragm test specimen.
8. The equivalent simulation test system for ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure as described in claim 6, characterized in that, Both the first and second clamps have curved surfaces that fit into the rubber diaphragm test piece. The end of the rigid loading rod is provided with a threaded hole. The fixing member is a bolt that passes through the first clamp, the through hole of the rubber diaphragm test piece and the second clamp and is threadedly connected to the threaded hole.
9. The equivalent simulation test system for ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure as described in claim 6, characterized in that, The first fixing ring and the second fixing ring have opposite annular grooves on opposite sides, and the edge area of the rubber diaphragm test piece is fitted into the annular groove.
10. The equivalent simulation test system for ultra-high cycle fatigue of a rubber diaphragm under pneumatic-hydraulic differential pressure as described in claim 6, characterized in that, The rigid loading rod is a cylindrical rod, and a sliding bearing is fitted on the rigid loading rod. The sliding bearing is used to guide the rigid loading rod and limit its radial displacement.