Method for obtaining failure rate of pressure compensator leather bag of underwater electro-hydraulic actuator

Abstract

The invention discloses a method for obtaining the failure rate of a pressure compensator leather bag of an underwater electro-hydraulic actuator, and relates to the technical field of deep sea equipment reliability testing, and the method comprises the following steps: carrying out a material performance test on a leather bag sample; performing finite element simulation on the leather bag sample; a multi-field coupling loading system is started to simulate actuator movement, a deep sea environment and a corrosion working condition, and an in-situ monitoring system is adopted to monitor strain distribution, abrasion loss, a crack propagation path and corrosion product components on the surface of the leather bag sample; judging whether failure occurs according to the leakage rate and the abrasion loss; establishing a failure time probability model based on Weibull distribution fitting; and extrapolating the failure rate under the actual working condition based on the inverse power law model. The failure rate of the pressure compensator leather bag of the underwater electro-hydraulic actuator is obtained by combining the multi-field coupling loading system, the in-situ monitoring system, Weibull distribution fitting and the inverse power law model, and the obtaining accuracy of the failure rate is improved.

Description

Technical Field

[0001] This application relates to the technical field of deep - sea equipment reliability testing, and particularly to a method for obtaining the failure rate of the bladder of a pressure compensator for an underwater electro - hydraulic actuator. Background Art

[0002] The bladder of the pressure compensator of an underwater electro - hydraulic actuator is a core component for maintaining the pressure balance inside and outside the system. Its failure modes include fatigue rupture, corrosion perforation, and material aging. It is necessary to study the technology for obtaining the failure rate of the bladder of the pressure compensator of an underwater electro - hydraulic actuator to improve the reliability of the underwater electro - hydraulic actuator.

[0003] Currently, generally, traditional fatigue tests are used to simulate mechanical cyclic loads, and off - line weighing, pressure decay method, or acoustic emission monitoring is used to determine whether the bladder fails.

[0004] However, the existing technology for obtaining the failure rate of the bladder of the pressure compensator of an underwater electro - hydraulic actuator does not consider the influence of the deep - sea environment and corrosion conditions on the failure rate. Moreover, off - line weighing and the pressure decay method cannot detect micro - leakage situations, and acoustic emission monitoring lacks the ability to identify characteristics of multiple failure modes (such as crack propagation and material swelling). At the same time, it is difficult for the existing technology to quantify the acceleration effect of corrosion on the fatigue life. In summary, the accuracy of obtaining the failure rate by the existing technology is poor. Summary of the Invention

[0005] This application provides a method for obtaining the failure rate of the bladder of a pressure compensator for an underwater electro - hydraulic actuator to solve the problem of poor accuracy in obtaining the failure rate in the existing technology for obtaining the failure rate of the bladder of the pressure compensator of an underwater electro - hydraulic actuator.

[0006] On the one hand, this application provides a method for obtaining the failure rate of the bladder of a pressure compensator for an underwater electro - hydraulic actuator, including the following steps: Step 1, conduct material property tests on the bladder samples and record the initial mechanical property parameters.

[0007] Step 2, perform finite - element simulation on the bladder samples according to the initial mechanical property parameters to determine the high - risk areas.

[0008] Step 3, construct a multi - field coupled loading system and an in - situ monitoring system.

[0009] Step 4, start the multi - field coupled loading system to simulate the movement of the actuator, the deep - sea environment, and the corrosion conditions, and use the in - situ monitoring system to periodically detect and disassemble and analyze the high - risk areas of the bladder samples, and monitor the strain distribution, wear amount, crack propagation path, and corrosion product composition on the surface of the bladder samples.

[0010] Step 5: Monitor the leakage rate of the bladder sample in real time, and determine whether it fails based on the leakage rate and the wear amount to obtain the failure time data.

[0011] Step 6: Based on Weibull distribution fitting, establish a failure time probability model according to the failure time data.

[0012] Step 7: Based on the inverse power law model, extrapolate the failure rate under actual working conditions according to the failure time probability model.

[0013] In a possible implementation manner, in Step 1, the material property test includes: hardness test, tensile strength test, and compression set test.

[0014] In a possible implementation manner, in Step 3, the multi-field coupling loading system includes: a mechanical cycle module, an environment simulation module, and a corrosion medium module.

[0015] The mechanical cycle module is used to simulate the movement of the actuator.

[0016] The environment simulation module is used to simulate the deep-sea environment.

[0017] The corrosion medium module is used to simulate the corrosion working condition.

[0018] In a possible implementation manner, the deep-sea environment includes: deep-sea water pressure environment, deep-sea temperature environment, and electrochemical corrosion environment.

[0019] In a possible implementation manner, in Step 3, the in-situ monitoring system includes: an optical fiber sensing network and a microscopic observation module.

[0020] The optical fiber sensing network is used to monitor the strain distribution on the surface of the bladder sample.

[0021] The microscopic observation module is used to monitor the wear amount, crack propagation path, and corrosion product composition on the surface of the bladder sample.

[0022] In a possible implementation manner, in Step 5, a threshold comparison method is used to determine whether it fails according to the leakage rate and the wear amount, including: When the leakage rate is greater than or equal to the preset leakage rate threshold, or when the wear amount is greater than or equal to the preset wear amount threshold, it is determined that the bladder sample fails; otherwise, it is determined that it does not fail.

[0023] In a possible implementation manner, in Step 6, the maximum likelihood method is used to estimate the Weibull distribution parameters according to the failure time data, including the characteristic life and the shape parameter, and establish a failure time probability model.

[0024] In a possible implementation, the method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator further includes: Step Eight, based on the extrapolated failure rate under actual working conditions, and in combination with the strain distribution, the crack propagation path, and the corrosion product composition, optimize the design of the pressure compensator bladder.

[0025] The design optimization includes: structural optimization and material modification.

[0026] The method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator in this application has the following advantages: By combining a multi-field coupling loading system, an in-situ monitoring system, Weibull distribution fitting, and an inverse power law model to obtain the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator. Among them, the multi-field coupling loading system can simulate the actuator movement, deep-sea environment, and corrosion working conditions, the in-situ monitoring system can monitor the strain distribution, wear amount, crack propagation path, and corrosion product composition on the surface of the bladder sample, and Weibull distribution fitting and the inverse power law model can quantify the acceleration effect of corrosion on the fatigue life. Overall, the accuracy of obtaining the failure rate is improved. Description of the Drawings

[0027] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a schematic flowchart of the method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator provided in the embodiment of the present application; Figure 2 It is a schematic structural diagram of the multi-field coupling loading system and the in-situ monitoring system provided in the embodiment of the present application.

[0029] Description of the Reference Numerals: 1 - Double-rod cylinder oil pumping system, 2 - Driving cylinder, 3 - Supplementary cylinder, 4 - Compensator, 5 - First one-way valve, 6 - First spring one-way valve, 7 - Second one-way valve, 8 - Second spring one-way valve, 9 - First valve, 10 - Second valve, 11 - First cavity interface, 12 - Second cavity interface, 13 - First interface, 14 - Second interface, 15 - Third valve, 16 - Fourth valve, 17 - Pressure sensor, 18 - First temperature sensor, 19 - Second temperature sensor. Detailed Embodiments

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0031] As Figure 1 shown, the embodiment of the present application provides a method for obtaining the failure rate of the pressure compensator bladder of an underwater electro-hydraulic actuator, including the following steps: Step 1: Conduct material property tests on the bladder samples and record the initial mechanical property parameters.

[0032] Step 2: Perform finite element simulation on the bladder samples according to the initial mechanical property parameters to determine the high-risk areas.

[0033] Step 3: Construct a multi-field coupled loading system and an in-situ monitoring system.

[0034] Step 4: Start the multi-field coupled loading system to simulate the actuator movement, deep-sea environment, and corrosion conditions. Use the in-situ monitoring system to perform periodic detection and periodic disassembly analysis on the high-risk areas of the bladder samples, and monitor the strain distribution, wear amount, crack propagation path, and corrosion product composition on the surface of the bladder samples.

[0035] Step 5: Real-time monitor the leakage rate of the bladder samples, and determine whether they fail according to the leakage rate and the wear amount to obtain the failure time data.

[0036] Step 6: Based on Weibull distribution fitting, establish a failure time probability model according to the failure time data.

[0037] Step 7: Based on the inverse power law model, extrapolate the failure rate under actual working conditions according to the failure time probability model.

[0038] Exemplarily, in Step 1, the material property tests include: hardness test, tensile strength test, and compression permanent deformation test.

[0039] Specifically, in this embodiment, in Step 1, a Shore A durometer is used to perform a hardness test on the bladder samples, the tensile strength test on the bladder samples is performed according to the GB / T528 standard, and a dynamic mechanical analyzer is used to perform a compression permanent deformation test on the bladder samples.

[0040] Specifically, in this embodiment, in Step 2, based on the Abaqus finite element simulation software, finite element simulation is performed on the bladder samples according to the initial mechanical property parameters to determine the high-risk areas (such as the root of the wrinkles of the bladder samples) as the monitoring focus.

[0041] Exemplarily, in step three, the multi-field coupling loading system includes: a mechanical cycling module, an environmental simulation module, and a corrosion medium module.

[0042] The mechanical cycling module is used to simulate the movement of the actuator.

[0043] The environmental simulation module is used to simulate the deep-sea environment.

[0044] The corrosion medium module is used to simulate the corrosion working conditions.

[0045] Exemplarily, the deep-sea environment includes: deep-sea water pressure environment, deep-sea temperature environment, and electrochemical corrosion environment.

[0046] Specifically, in this embodiment, the mechanical cycling module uses a servo hydraulic testing machine to apply axial cyclic displacement (±20 mm, frequency 0.1 - 5 Hz) to the bladder sample to simulate the movement of the actuator.

[0047] The environmental simulation module integrates a deep-sea high-pressure chamber (0 - 30 MPa water pressure) and a temperature control system (5 - 40 °C), and is equipped with an electrochemical workstation (polarization voltage 0 - 100 mV) to simulate the deep-sea water pressure environment, deep-sea temperature environment, and electrochemical corrosion environment.

[0048] The corrosion medium module uses artificial seawater (NaCl concentration 3.5%) and a pH adjustment system (2 - 12) to simulate the corrosion working conditions.

[0049] Exemplarily, in step three, the in-situ monitoring system includes: an optical fiber sensing network and a microscopic observation module.

[0050] The optical fiber sensing network is used to monitor the strain distribution on the surface of the bladder sample.

[0051] The microscopic observation module is used to monitor the wear amount, crack propagation path, and corrosion product composition on the surface of the bladder sample.

[0052] Specifically, in this embodiment, the optical fiber sensing network uses a distributed optical fiber sensor (strain resolution 1 με) to monitor the strain distribution on the surface of the bladder sample and can identify stress concentration areas.

[0053] The microscopic observation module includes: a high-speed camera (frame rate 1000 fps), a laser confocal microscope (accuracy 0.1 μm), and an energy spectrometer. The high-speed camera is used to monitor the wear amount on the surface of the bladder sample, the laser confocal microscope is used to monitor the crack propagation path on the surface of the bladder sample, and the energy spectrometer is used to monitor the corrosion product composition on the surface of the bladder sample.

[0054] Specifically, in this embodiment, in step four, every 10 4Perform a periodic detection (shutdown detection) for each cyclic displacement, and use an optical fiber sensing network to monitor the strain distribution on the surface of the bladder sample; every 10 5 Perform a periodic disassembly analysis (disassemble the bladder sample) for each cyclic displacement, and use a microscopic observation module to monitor the wear amount, crack propagation path, and corrosion product composition on the surface of the bladder sample.

[0055] Exemplarily, in step five, determine whether it fails according to the leakage rate and the wear amount by using a threshold comparison method, including: When the leakage rate is greater than or equal to a preset leakage rate threshold, or when the wear amount is greater than or equal to a preset wear amount threshold, determine that the bladder sample fails; otherwise, determine that it does not fail.

[0056] Specifically, in this embodiment, in step five, the leakage rate threshold is set to 1×10 -6 Pa・m³ / s, and the wear amount threshold is set to 0.2 mm.

[0057] Exemplarily, in step six, use the maximum likelihood method to estimate the Weibull distribution parameters according to the failure time data, including the characteristic life and the shape parameter, and establish a failure time probability model.

[0058] Specifically, in this embodiment, in step seven, the formula of the inverse power law model is as follows: lnη = a + b / p + c / T + dE.

[0059] Where, η represents the characteristic life, a represents the basic life constant, b represents the pressure sensitivity coefficient, p represents the value of the simulated deep-sea water pressure environment (water pressure value), c represents the temperature sensitivity coefficient, T represents the value of the simulated deep-sea temperature environment (temperature value), d represents the electrochemical sensitivity coefficient, and E represents the value of the simulated electrochemical corrosion environment (electrochemical potential value).

[0060] The calculation formula of the failure rate is as follows: .

[0061] Where, represents the failure rate at time t, η represents the characteristic life, represents the shape parameter.

[0062] Exemplarily, the method for obtaining the failure rate of the pressure compensator bladder of an underwater electro-hydraulic actuator further includes: step eight, design optimization of the pressure compensator bladder according to the extrapolated failure rate under actual working conditions, in combination with the strain distribution, the crack propagation path, and the corrosion product composition.

[0063] The design optimization includes: structural optimization and material modification.

[0064] Specifically, for the strain distribution and crack propagation path, structural optimization can be carried out (such as reducing the fold angle, etc.), and for the composition of corrosion products, material modification can be carried out (such as adding a corrosion-resistant coating, etc.).

[0065] Such as Figure 2 The principle structure diagrams of the multi-field coupling loading system and the in-situ monitoring system are shown as follows.

[0066] Figure 2 The component connection relationships in Oil circuit connection: The double-rod cylinder pumping system 1 is connected to the first cavity interface 11 and the second cavity interface 12 of the compensator 4 through pipelines to form an oil circulation channel. When the piston rod of the double-rod cylinder pumping system 1 pushes and pulls, it pumps oil to the first cavity interface 11 and the second cavity interface 12 alternately. The supplementary oil cylinder 3 is connected to the first interface 13 of the first cavity interface 11 and the second interface 14 of the second cavity interface 12 through pipelines for initial oil filling. The third valve 15 is connected in series in the oil circuit of the first cavity interface 11 to control the one-way flow of the oil in the first cavity interface 11; the fourth valve 16 is connected in series in the oil circuit of the second cavity interface 12 to control the one-way flow of the oil in the second cavity interface 12.

[0067] Check valve connection: The first check valve 5 is connected in series in the oil circuit from the double-rod cylinder pumping system 1 to the first cavity interface 11, and the second check valve 7 is connected in series in the oil circuit from the double-rod cylinder pumping system 1 to the second cavity interface 12. The first spring check valve 6 is connected in parallel between the supplementary oil cylinder 3 and the first interface 13, and the second spring check valve 8 is connected in parallel between the supplementary oil cylinder 3 and the second interface 14.

[0068] Corrosion medium pipeline: The first valve 9 connects the outlet of the corrosion medium module to the immersion cavity of the compensator 4, and the second valve 10 connects the immersion cavity of the compensator 4 to the recovery device.

[0069] Sensor integration: The pressure sensor 17 is installed in the main oil circuit, and the first temperature sensor 18 and the second temperature sensor 19 are installed in the corrosion medium pipeline and embedded in the environmental simulation module.

[0070] Mechanical connection: The driving oil cylinder 2 is connected to the piston rod of the double-rod cylinder pumping system 1 or the compensator tooling through a mechanical structure to drive the double-rod cylinder pumping system 1 to act.

[0071] Figure 2 The system operation principle in Initial oil filling and air exhausting process: Before the test starts, push the piston of the oil replenishing cylinder 3 to the rightmost position and keep it there. Open the fourth valve 16 and close the third valve 15. Fill hydraulic oil into the second cavity interface 12 from the second interface 14, and exhaust air through the second interface 14 at the same time to make the bladder expand to the maximum state. Continue to fill oil until the pressure at the second cavity interface 12 reaches 0.4 - 0.5 MPa (reaching the opening pressure of the oil return check valve), and then keep the pressure unchanged. Open the third valve 15 and close the fourth valve 16. Fill hydraulic oil into the first cavity interface 11 from the first interface 13, and exhaust air through the first interface 13 at the same time. Ensure that the bladder is not compressed during the oil filling process. Similarly, add the pressure to 0.4 - 0.5 MPa. At this time, it is observed that the bladder is in the maximum state, and then close the third valve 15 and the fourth valve 16 to complete the oil filling and air exhausting. Open the second spring check valve 8 and the fourth valve 16. The oil replenishing cylinder 3 injects oil into the second cavity interface 12 through the second interface 14, and the second check valve 7 prevents the oil from flowing back. Open the first spring check valve 6 and the third valve 15. The oil replenishing cylinder 3 injects oil into the first cavity interface 11 through the first interface 13, and the first check valve 5 prevents the oil from flowing back. The pressure sensor 17 monitors the oil pressure in real time to ensure that it is stable at 0.4 - 0.5 MPa.

[0072] Fatigue test cycle process: Calculate the stroke of the driving cylinder 2 according to the oil replenishment amount, and determine its stroke range through no-load operation. Limit the stroke at the corresponding position through the mechanical limit device to prevent damage to the bladder caused by excessive oil. The driving cylinder 2 makes reciprocating motions, driving the piston rod of the double-rod cylinder oil pumping system 1 to push and pull. When the piston rod moves to the left, pump oil into the first cavity interface 11 to make the bladder contract; when the piston rod moves to the right, pump oil into the second cavity interface 12 to make the bladder expand. Repeat this process to simulate the contraction and expansion actions of the bladder in actual work and conduct a fatigue test on the bladder. During the test, the counter records the number of reciprocating motions of the driving cylinder 2 in real time. When the bladder is damaged or reaches the preset number of cycles, the test ends. The driving cylinder 2 drives the piston of the double-rod cylinder oil pumping system 1 to move: when the piston moves to the left, the first check valve 5 conducts, and the hydraulic oil is pressed into the first cavity interface 11 to make the bladder contract; the second spring check valve 8 opens to replenish oil at low pressure. When the piston moves to the right, the second check valve 7 conducts, and the hydraulic oil is pressed into the second cavity interface 12 to make the bladder expand; the first spring check valve 6 opens to replenish oil at low pressure.

[0073] Corrosion working condition simulation: Open the first valve 9 and the second valve 10, and circulate through the surface of the bladder after controlling the flow rate.

[0074] Failure monitoring: The sudden change of the pressure sensor 17 indicates leakage.

[0075] The first temperature sensor 18 and the second temperature sensor 19 feedback data to the environmental simulation module to dynamically adjust the oil temperature.

[0076] In the embodiments of the present application, a failure rate of a bladder of a pressure compensator of an underwater electro-hydraulic actuator is obtained by combining a multi-field coupling loading system, an in-situ monitoring system, Weibull distribution fitting, and an inverse power law model. Among them, the multi-field coupling loading system can simulate the actuator movement, deep-sea environment, and corrosion conditions. The in-situ monitoring system can monitor the strain distribution, wear amount, crack propagation path, and corrosion product composition on the surface of the bladder sample. The Weibull distribution fitting and the inverse power law model can quantify the acceleration effect of corrosion on the fatigue life. Collectively, the accuracy of obtaining the failure rate is improved.

[0077] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications that fall within the scope of the present application.

[0078] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A method for obtaining the failure rate of the bladder of the pressure compensator of an underwater electro-hydraulic actuator, characterized in that, It includes the following steps: Step 1: Conduct material property tests on the bladder samples and record the initial mechanical property parameters; Step 2: Perform finite element simulation on the bladder samples according to the initial mechanical property parameters to determine the high-risk areas; Step 3: Construct a multi-field coupling loading system and an in-situ monitoring system; Step 4: Start the multi-field coupling loading system to simulate the actuator movement, deep-sea environment, and corrosion conditions. Use the in-situ monitoring system to conduct periodic detection and periodic disassembly analysis on the high-risk areas of the bladder samples, and monitor the strain distribution, wear amount, crack propagation path, and corrosion product composition on the surface of the bladder samples; Step 5: Real-time monitor the leakage rate of the bladder samples, and judge whether it fails according to the leakage rate and the wear amount to obtain the failure time data; Step 6: Based on Weibull distribution fitting, establish a failure time probability model according to the failure time data; Step 7: Based on the inverse power law model, extrapolate the failure rate under actual working conditions according to the failure time probability model.

2. The method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator according to claim 1, characterized in that, In Step 1, the material property tests include: hardness test, tensile strength test, and compression permanent deformation test.

3. The method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator according to claim 1, characterized in that, In Step 3, the multi-field coupling loading system includes: a mechanical cycle module, an environment simulation module, and a corrosion medium module; The mechanical cycle module is used to simulate the actuator movement; The environment simulation module is used to simulate the deep-sea environment; The corrosion medium module is used to simulate the corrosion conditions.

4. The method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator according to claim 1, characterized in that, The deep-sea environment includes: deep-sea water pressure environment, deep-sea temperature environment, and electrochemical corrosion environment.

5. The method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator according to claim 1, characterized in that In Step 3, the in-situ monitoring system includes: an optical fiber sensing network and a microscopic observation module; The optical fiber sensing network is used to monitor the strain distribution on the surface of the bladder samples; The microscopic observation module is used to monitor the wear amount, crack propagation path, and corrosion product composition on the surface of the bladder samples.

6. The method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator according to claim 1, characterized in that, In Step 5, the method of judging whether it fails according to the leakage rate and the wear amount by threshold comparison includes: When the leakage rate is greater than or equal to the preset leakage rate threshold, or when the wear amount is greater than or equal to the preset wear amount threshold, it is judged that the bladder sample fails, otherwise it is judged not to fail.

7. The method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator according to claim 1, characterized in that In Step 6, the Weibull distribution parameters, including the characteristic life and the shape parameter, are estimated according to the failure time data by the maximum likelihood method to establish a failure time probability model.

8. The method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator according to claim 1, characterized in that, It also includes: Step 8, according to the extrapolated failure rate under actual working conditions, combined with the strain distribution, the crack propagation path, and the corrosion product composition, optimize the design of the pressure compensator bladder; The design optimization includes: structural optimization and material modification.

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