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

Abstract

The present invention discloses a method for obtaining the failure rate of a pressure compensator bladder for an underwater electro-hydraulic actuator, relating to the technical field of deep-sea equipment reliability testing. The method comprises the following steps: conducting material property testing on a bladder sample; performing finite element simulation on the bladder sample; activating a multi-field coupling loading system to simulate actuator motion, deep-sea environment, and corrosion conditions, and using an in-situ monitoring system to monitor the strain distribution, wear, crack propagation path, and corrosion product composition on the surface of the bladder sample; determining failure based on leakage rate and wear; establishing a failure time probability model based on Weibull distribution fitting; and extrapolating the failure rate under actual operating conditions based on an inverse power law model. This application improves the accuracy of failure rate acquisition 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 for an underwater electro-hydraulic actuator.

Description

Technical Field

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

[0002] The pressure compensator bladder of an underwater electro-hydraulic actuator is a core component that maintains internal and external pressure balance in the system. Its failure modes include fatigue cracking, corrosion perforation, and material aging. Research is needed on techniques to determine the failure rate of the pressure compensator bladder in underwater electro-hydraulic actuators to improve their reliability.

[0003] At present, mechanical cyclic loads are generally simulated through traditional fatigue tests, and whether the bladder has failed is determined by offline weighing, pressure decay method or acoustic emission monitoring.

[0004] However, existing technologies for determining failure rates for pressure compensator bladders in underwater electro-hydraulic actuators fail to account for the impact of deep-sea environments and corrosive conditions on failure rates. Furthermore, offline weighing and pressure decay methods cannot detect micro-leaks, and acoustic emission monitoring lacks the ability to identify the characteristics of multiple failure modes (such as crack propagation and material swelling). Furthermore, existing technologies struggle to quantify the accelerated effects of corrosion on fatigue life. Consequently, existing technologies for determining failure rates suffer from poor accuracy. Summary of the Invention

[0005] The present application provides a method for obtaining the failure rate of a pressure compensator bladder of an underwater electro-hydraulic actuator, so as to solve the problem of poor accuracy in the failure rate acquisition technology of the pressure compensator bladder of an underwater electro-hydraulic actuator.

[0006] In one aspect, the present application provides a method for obtaining the failure rate of a pressure compensator bladder of an underwater electro-hydraulic actuator, comprising the following steps:

[0007] Step 1: Perform material performance tests on the skin bag sample and record the initial mechanical performance parameters.

[0008] Step 2: Perform finite element simulation on the skin bag sample according to the initial mechanical performance parameters to determine the high-risk area.

[0009] Step three: construct a multi-field coupled loading system and in-situ monitoring system.

[0010] Step 4: Start the multi-field coupling loading system to simulate the actuator movement, deep-sea environment, and corrosion conditions, and use the in-situ monitoring system to perform periodic inspection and periodic disassembly analysis on the high-risk areas of the bladder sample to monitor the strain distribution, wear amount, crack propagation path, and corrosion product composition on the surface of the bladder sample.

[0011] Step 5: monitor the leakage rate of the bladder sample in real time, determine whether it is failed based on the leakage rate and the wear amount, and obtain failure time data.

[0012] Step six: Based on Weibull distribution fitting, a failure time probability model is established according to the failure time data.

[0013] Step seven: Based on the inverse power law model, the failure rate under actual working conditions is extrapolated according to the failure time probability model.

[0014] In a possible implementation, in step 1, the material performance test includes: a hardness test, a tensile strength test, and a compression set test.

[0015] In a possible implementation, in step three, the multi-field coupling loading system includes: a mechanical circulation module, an environmental simulation module, and a corrosive medium module.

[0016] The mechanical cycle module is used to simulate the actuator movement.

[0017] The environmental simulation module is used to simulate the deep sea environment.

[0018] The corrosive medium module is used to simulate corrosion conditions.

[0019] In a possible implementation, the deep sea environment includes: a deep sea water pressure environment, a deep sea temperature environment, and an electrochemical corrosion environment.

[0020] In one possible implementation, in step three, the in-situ monitoring system includes: a fiber optic sensing network and a microscopic observation module.

[0021] The optical fiber sensing network is used to monitor the strain distribution on the surface of the leather bag sample.

[0022] The microscopic observation module is used to monitor the wear amount, crack propagation path and corrosion product composition of the skin sample surface.

[0023] In one possible implementation, in step five, determining whether failure has occurred based on the leakage rate and the wear amount by using a threshold comparison method includes:

[0024] 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, the bladder sample is judged to be invalid; otherwise, it is judged to be not invalid.

[0025] In a possible implementation, in step six, the maximum likelihood method is used to estimate the Weibull distribution parameters, including characteristic life and shape parameters, based on the failure time data, and a failure time probability model is established.

[0026] In one possible implementation, the method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator also includes: step eight, based on the failure rate under extrapolated actual working conditions, combined with the strain distribution, the crack propagation path, and the corrosion product composition, the pressure compensator bladder is designed and optimized.

[0027] The design optimization includes: structure optimization and material modification.

[0028] 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:

[0029] The failure rate of the pressure compensator bladder of an underwater electro-hydraulic actuator is determined by combining a multi-field coupled loading system, an in-situ monitoring system, Weibull distribution fitting, and an inverse power law model. The multi-field coupled loading system simulates actuator motion, deep-sea environments, and corrosion conditions. The in-situ monitoring system measures the strain distribution, wear volume, crack propagation path, and corrosion product composition on the bladder sample surface. The Weibull distribution fitting and inverse power law model quantify the accelerated effect of corrosion on fatigue life. Together, these methods improve the accuracy of failure rate determination. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A flow chart of a method for obtaining the failure rate of a pressure compensator bladder of an underwater electro-hydraulic actuator provided in an embodiment of the present application;

[0032] Figure 2 This is a schematic diagram of the principle structure of the multi-field coupling loading system and in-situ monitoring system provided in the embodiments of the present application.

[0033] Description of reference numerals:

[0034] 1-Double-rod cylinder pump oil system, 2-Drive cylinder, 3-Supplementary oil 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 DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] like Figure 1 As shown, the embodiment of the present application provides a method for obtaining the failure rate of a pressure compensator bladder of an underwater electro-hydraulic actuator, comprising the following steps:

[0037] Step 1: Perform material performance tests on the skin bag sample and record the initial mechanical performance parameters.

[0038] Step 2: Perform finite element simulation on the skin bag sample according to the initial mechanical performance parameters to determine the high-risk area.

[0039] Step three: construct a multi-field coupled loading system and in-situ monitoring system.

[0040] Step 4: Start the multi-field coupling loading system to simulate the actuator movement, deep-sea environment, and corrosion conditions, and use the in-situ monitoring system to perform periodic inspection and periodic disassembly analysis on the high-risk areas of the bladder sample to monitor the strain distribution, wear amount, crack propagation path, and corrosion product composition on the surface of the bladder sample.

[0041] Step 5: monitor the leakage rate of the bladder sample in real time, determine whether it is failed based on the leakage rate and the wear amount, and obtain failure time data.

[0042] Step six: Based on Weibull distribution fitting, a failure time probability model is established according to the failure time data.

[0043] Step seven: Based on the inverse power law model, the failure rate under actual working conditions is extrapolated according to the failure time probability model.

[0044] Illustratively, in step one, the material performance test includes: hardness test, tensile strength test, and compression permanent deformation test.

[0045] Specifically, in this embodiment, in step one, a Shore A durometer is used to perform a hardness test on the bladder sample, a tensile strength test is performed on the bladder sample according to the GB / T528 standard, and a dynamic mechanical analyzer is used to perform a compression permanent deformation test on the bladder sample.

[0046] Specifically, in this embodiment, in step 2, based on the Abaqus finite element simulation software, the finite element simulation of the bladder sample is performed according to the initial mechanical performance parameters, and the high-risk area (such as the root of the wrinkle of the bladder sample) is determined as the monitoring focus.

[0047] Exemplarily, in step three, the multi-field coupling loading system includes: a mechanical circulation module, an environmental simulation module, and a corrosive medium module.

[0048] The mechanical cycle module is used to simulate the actuator movement.

[0049] The environmental simulation module is used to simulate the deep sea environment.

[0050] The corrosive medium module is used to simulate corrosion conditions.

[0051] Exemplarily, the deep sea environment includes: deep sea water pressure environment, deep sea temperature environment, and electrochemical corrosion environment.

[0052] Specifically, in this embodiment, the mechanical cycle 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.

[0053] The environmental simulation module integrates a deep-sea hyperbaric chamber (0-30MPa water pressure) and a temperature control system (5-40°C), and is equipped with an electrochemical workstation (polarization voltage 0-100mV) to simulate the deep-sea water pressure environment, deep-sea temperature environment, and electrochemical corrosion environment.

[0054] The corrosion medium module uses artificial seawater (NaCl concentration 3.5%) and a pH adjustment system (2-12) to simulate corrosion conditions.

[0055] Exemplarily, in step three, the in-situ monitoring system includes: a fiber optic sensing network and a microscopic observation module.

[0056] The optical fiber sensing network is used to monitor the strain distribution on the surface of the leather bag sample.

[0057] The microscopic observation module is used to monitor the wear amount, crack propagation path and corrosion product composition of the skin sample surface.

[0058] Specifically, in this embodiment, the optical fiber sensing network uses distributed optical fiber sensors (strain resolution 1 με) to monitor the strain distribution on the surface of the skin bag sample and can identify stress concentration areas.

[0059] The microscopic observation module includes: a high-speed camera (frame rate 1000fps), a laser confocal microscope (accuracy 0.1μm), and an energy spectrometer. The high-speed camera is used to monitor the wear amount on the surface of the leather sample, the laser confocal microscope is used to monitor the crack propagation path on the surface of the leather sample, and the energy spectrometer is used to monitor the composition of corrosion products on the surface of the leather sample.

[0060] Specifically, in this embodiment, in step 4, every 10 4A periodic test (shutdown test) is performed every 10 cycles of displacement, and the strain distribution on the surface of the bag sample is monitored using a fiber optic sensor network; 5 A periodic disassembly analysis (disassembling the bladder sample) is performed with a cyclic displacement, and a microscopic observation module is used to monitor the wear amount, crack propagation path, and corrosion product composition of the bladder sample surface.

[0061] Exemplarily, in step 5, determining whether failure occurs based on the leakage rate and the wear amount by using a threshold comparison method includes:

[0062] 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, the bladder sample is judged to be invalid; otherwise, it is judged to be not invalid.

[0063] Specifically, in this embodiment, in step 5, the leakage rate threshold is set to 1×10 -6 Pa・m³ / s, and the wear threshold is set to 0.2mm.

[0064] Exemplarily, in step six, the maximum likelihood method is used to estimate the Weibull distribution parameters, including characteristic life and shape parameters, based on the failure time data, and a failure time probability model is established.

[0065] Specifically, in this embodiment, in step seven, the formula of the inverse power law model is as follows:

[0066] lnη=a+b / p+c / T+dE.

[0067] Among them, 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).

[0068] The failure rate is calculated as follows:

[0069] .

[0070] in, represents the failure rate at time t, η represents the characteristic life, Represents the shape parameter.

[0071] Exemplarily, the method for obtaining the failure rate of the pressure compensator bladder of the underwater electro-hydraulic actuator also includes: step eight, based on the failure rate under extrapolated actual working conditions, combined with the strain distribution, the crack propagation path, and the corrosion product composition, the pressure compensator bladder is designed and optimized.

[0072] The design optimization includes: structure optimization and material modification.

[0073] Specifically, structural optimization (such as reducing the wrinkle angle, etc.) can be carried out for the strain distribution and crack propagation path, and material modification (such as adding corrosion-resistant coating, etc.) can be carried out for the composition of corrosion products.

[0074] like Figure 2 Shown is the principle structure diagram of the multi-field coupling loading system and in-situ monitoring system.

[0075] Figure 2 The connection relationship between the components in is as follows:

[0076] Oil circuit connection: The double-rod oil cylinder pumping system 1 is connected to the first cavity interface 11 and the second cavity interface 12 of the compensator 4 through a pipeline, forming an oil circulation channel. When the piston rod of the double-rod oil cylinder pumping system 1 is pushed or pulled, oil is pumped alternately to the first cavity interface 11 and the second cavity interface 12. The oil replenishing 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 a pipeline for initial oil filling. The third valve 15 is connected in series to the oil circuit of the first cavity interface 11 to control the one-way flow of oil in the first cavity interface 11; the fourth valve 16 is connected in series to the oil circuit of the second cavity interface 12 to control the one-way flow of oil in the second cavity interface 12.

[0077] Check valve connections: The first check valve 5 is connected in series in the oil circuit from the dual-rod cylinder pump system 1 to the first cavity port 11. The second check valve 7 is connected in series in the oil circuit from the dual-rod cylinder pump system 1 to the second cavity port 12. The first spring check valve 6 is connected in parallel between the replenishment cylinder 3 and the first port 13, and the second spring check valve 8 is connected in parallel between the replenishment cylinder 3 and the second port 14.

[0078] Corrosive medium pipeline: the first valve 9 connects the outlet of the corrosive medium module to the immersion chamber of the compensator 4, and the second valve 10 connects the immersion chamber of the compensator 4 to the recovery device.

[0079] Sensor integration: The pressure sensor 17 is installed in the main oil circuit, the first temperature sensor 18 and the second temperature sensor 19 are installed in the corrosive medium pipeline, and are embedded in the environmental simulation module.

[0080] Mechanical connection: The driving cylinder 2 is connected to the piston rod or compensator tooling of the double-rod cylinder oil pumping system 1 through a mechanical structure to drive the double-rod cylinder oil pumping system 1 to operate.

[0081] Figure 2 The system operation principle in is as follows:

[0082] Initial oil filling and exhaust process: Before the test begins, push the piston of the oil replenishment cylinder 3 to the rightmost position and hold it there. Open the fourth valve 16 and close the third valve 15. Fill hydraulic oil from the second port 14 into the second chamber port 12 while exhausting oil through the second port 14, causing the bladder to expand to its maximum. Continue filling until the pressure at the second chamber port 12 reaches 0.4-0.5 MPa (reaching the opening pressure of the oil return check valve). Maintain this pressure. Open the third valve 15 and close the fourth valve 16. Fill hydraulic oil from the first port 13 into the first chamber port 11 while exhausting oil through the first port 13. Ensure that the bladder is not compressed during the filling process. Similarly, increase the pressure to 0.4-0.5 MPa. At this point, observe that the bladder is at its maximum. Then close the third and fourth valves 15, 16, completing the oil filling and exhaust process. Open the second spring check valve 8 and the fourth valve 16. Fill oil from the oil replenishment cylinder 3 into the second chamber port 12 through the second port 14. The second check valve 7 prevents oil from flowing back. Opening first spring-loaded check valve 6 and third valve 15 allows oil to flow from first port 13 to first chamber port 11. First check valve 5 prevents oil from flowing back. Pressure sensor 17 monitors the oil pressure in real time, ensuring it remains stable at 0.4-0.5 MPa.

[0083] Fatigue test cycle: The stroke of drive cylinder 2 is calculated based on the oil replenishment volume, and its travel range is determined by running the test unit at no-load. A mechanical limiter limits the stroke to a specific position to prevent damage to the bladder caused by excessive oil. Drive cylinder 2 reciprocates, driving the piston rod of the dual-rod cylinder pumping system 1 in a push-and-pull motion. When the piston rod moves left, oil is pumped into the first chamber interface 11, causing the bladder to contract. When the piston rod moves right, oil is pumped into the second chamber interface 12, causing the bladder to expand. This cycle repeats, simulating the actual expansion and contraction of the bladder and performing a fatigue test on the bladder. During the test, a counter records the number of reciprocating motions of drive cylinder 2 in real time. The test ends when the bladder is damaged or the preset number of cycles is reached. Drive cylinder 2 drives the piston of dual-rod cylinder pumping system 1 in motion. When the piston moves left, the first check valve 5 opens, allowing oil to flow into the first chamber interface 11, causing the bladder to contract. The second spring-loaded check valve 8 opens when the pressure is low, replenishing oil. When the piston moves to the right, the second one-way valve 7 is turned on, and oil is pressed into the second cavity interface 12 to expand the bladder; the first spring one-way valve 6 is opened to replenish oil at low pressure.

[0084] Corrosion condition simulation:

[0085] Open the first valve 9 and the second valve 10, and circulate the flow through the surface of the bladder after controlling the flow rate.

[0086] Failure monitoring:

[0087] A sudden change in the pressure sensor 17 indicates a leak.

[0088] The first temperature sensor 18 and the second temperature sensor 19 feed back data to the environmental simulation module to dynamically adjust the oil temperature.

[0089] The present embodiment combines a multi-field coupled loading system, an in-situ monitoring system, Weibull distribution fitting, and an inverse power law model to determine the failure rate of the pressure compensator bladder of an underwater electro-hydraulic actuator. The multi-field coupled loading system simulates actuator motion, deep-sea environments, and corrosive conditions. The in-situ monitoring system monitors the strain distribution, wear volume, crack propagation path, and corrosion product composition on the bladder sample surface. The Weibull distribution fitting and inverse power law model quantify the accelerated effect of corrosion on fatigue life. These combined methods improve the accuracy of failure rate determination.

[0090] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0091] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for obtaining the failure rate of a pressure compensator bladder of an underwater electro-hydraulic actuator, characterized in that: The following steps are involved: Step 1: Perform material performance testing on the skin bag sample and record the initial mechanical performance parameters; Step 2: performing finite element simulation on the skin bag sample according to the initial mechanical performance parameters to determine high-risk areas; Step 3: Construct a multi-field coupled loading system and an in-situ monitoring system; Step 4: Start the multi-field coupled loading system to simulate the actuator motion, deep-sea environment, and corrosion conditions, and use the in-situ monitoring system to periodically detect and periodically disassemble and analyze the high-risk areas of the bladder sample to monitor the strain distribution, wear volume, crack propagation path, and corrosion product composition on the surface of the bladder sample; Step 5: monitoring the leakage rate of the bladder sample in real time, determining whether it is failed based on the leakage rate and the wear amount, and obtaining failure time data; Step 6: Based on Weibull distribution fitting, a failure time probability model is established 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; In step 3, the multi-field coupling loading system includes: a mechanical circulation module, an environmental simulation module, and a corrosive medium module; The mechanical cycle module is used to simulate the movement of the actuator; The environmental simulation module is used to simulate the deep sea environment; The corrosive medium module is used to simulate corrosion conditions; In step 3, the in-situ monitoring system includes: a fiber optic sensing network and a microscopic observation module; The optical fiber sensing network is used to monitor the strain distribution on the surface of the leather bag sample; The microscopic observation module is used to monitor the wear amount, crack propagation path, and corrosion product composition of the skin sample surface; In step 6, the maximum likelihood method is used to estimate the Weibull distribution parameters, including characteristic life and shape parameters, based on the failure time data, and a failure time probability model is established; In step seven, the formula for the inverse power law model is as follows: lnη=a+b / p+c / T+dE; Wherein, η represents characteristic life, a represents basic life constant, b represents pressure sensitivity coefficient, p represents the value of simulated deep-sea water pressure environment, c represents temperature sensitivity coefficient, T represents the value of simulated deep-sea temperature environment, d represents electrochemical sensitivity coefficient, and E represents the value of simulated electrochemical corrosion environment; The failure rate is calculated as follows: ； in, represents the failure rate at time t, η represents the characteristic life, Represents the shape parameter.

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 performance test includes: 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: The deep sea environment includes: deep sea water pressure environment, deep sea temperature environment, and electrochemical corrosion environment.

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: In step 5, a threshold comparison method is used to determine whether failure has occurred based on the leakage rate and the wear amount, 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, the bladder sample is judged to be invalid; otherwise, it is judged to be not invalid.

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: The method further includes: step eight, optimizing the design of the pressure compensator bladder based on the extrapolated failure rate under actual working conditions, combined with the strain distribution, the crack propagation path, and the corrosion product composition; The design optimization includes: structure optimization and material modification.

Images