A method and system for detecting the sealing performance of a spherical underwater connector

Abstract

The present invention relates to a method and system for testing the sealing performance of a spherical underwater connector. Dry inert gas with the same working pressure is injected into the sealing ring through a pressure measuring hole. A sinusoidal deflection motion of 5 to 15° and 0.1-1 Hz is applied to the sphere, and the dynamic working condition of the underwater pipeline subjected to long-term impact of ocean currents is simulated through a short-term extreme periodic deflection motion. At the same time, the pressure fluctuation amplitude ΔP is recorded at a sampling frequency of ≥10 Hz, and the first cycle ΔP0 is used as a reference to regularly measure ΔPn to construct a ΔP(t) curve. The critical threshold ΔPmax is determined experimentally, and the duration from ΔP0 to ΔPmax is calculated based on the ΔP(t) curve as the predicted service life. This invention realizes real-time status detection and long-term performance evaluation of the sealing ring through short-term extreme dynamic loading and high-frequency monitoring, solving the problem that traditional static detection cannot predict the degradation of sealing performance under alternating stress.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing performance detection of spherical underwater connectors, and in particular to a method and system for sealing performance detection of spherical underwater connectors. Background Art

[0002] Underwater connectors are key components in marine oil and gas production, submarine cable laying, and deep-sea observation systems. Their sealing performance directly impacts the safety and reliability of these devices. Spherical underwater connectors, in particular, are widely used in dynamic marine environments because they can accommodate relative motion between pipes.

[0003] In actual operation, seals not only need to withstand static water pressure, but are also subjected to continuous cyclical stress due to external factors such as ocean current impact and mechanical vibration, which can gradually fatigue the material and ultimately cause seal failure. However, current seal detection methods mainly focus on immediate detection after installation. For example, gas is introduced into the pressure measuring hole of the flange to determine whether the seal is properly installed or leaks based on the changes in gas flow. Although this method can verify the installation quality, it only reflects the current status and cannot assess the performance degradation trend of the seal under long-term dynamic loads.

[0004] The limitation of existing technology is that it only focuses on static or short-term sealing detection, but ignores the problem of long-term alternating stress that the sealing ring is subjected to under actual working conditions. Due to the lack of dynamic simulation and long-term performance prediction methods, operation and maintenance personnel can only rely on regular inspections or passively wait for leaks to occur, which not only increases maintenance costs but may also lead to serious safety accidents due to sudden failure. Summary of the Invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the limitations of the existing technology in the detection of the sealing performance of spherical underwater connectors. The proposed dynamic sealing detection method, by accurately simulating the actual stress environment of the underwater connector and combining it with pressure monitoring, not only realizes the instant detection of the sealing ring, but also can accurately evaluate its long-term performance.

[0006] To solve the above technical problems, the present invention provides a method for testing the sealing performance of a spherical underwater connector. The spherical underwater connector includes a sphere and a flange. The sphere and the flange are fitted together to form a seal through a sealing ring. A pressure measuring hole that passes through the sealing ring is opened on the flange. Gas is passed into the pressure measuring hole to test the sealing performance of the sealing ring. The method includes the following steps:

[0007] Inject dry inert gas into the sealing ring through the pressure measuring hole. The pressure of the injected inert gas is the same as the pressure of the spherical underwater connector when it is working underwater.

[0008] A periodic deflection motion is applied to the sphere, causing it to deflect sinusoidally relative to the flange. The unidirectional deflection angle is set to 5-15° based on the statistical value of the maximum angular displacement of the pipeline joint under actual ocean current impact. The frequency is set to 0.1-1Hz based on the multiple acceleration coefficient of the typical ocean current vortex shedding frequency. The dynamic working conditions of the underwater pipeline subjected to long-term ocean current impact are simulated through short-term extreme periodic deflection motion.

[0009] While applying periodic deflection motion, record the pressure fluctuation amplitude ΔP of the injected gas at a sampling frequency of not less than 10 Hz. Record the pressure fluctuation amplitude ΔP0 of the first deflection motion cycle after pressurization is stabilized and use it as the pressure fluctuation reference amplitude. Repeat the pressure fluctuation amplitude ΔPn at regular intervals to construct a pressure fluctuation amplitude change curve ΔP(t).

[0010] The critical threshold value ΔPmax of the pressure fluctuation amplitude is determined experimentally, and the duration of the increase from the initial reference value ΔP0 to ΔPmax is calculated according to the pressure fluctuation amplitude change curve ΔP(t), which is the predicted service life of the spherical underwater connector.

[0011] In one embodiment of the present invention, the step of injecting dry inert gas into the sealing ring through the pressure measuring hole includes:

[0012] Pre-pressurization stage: Inject inert gas into the pressure measuring hole in a stepped pressurization manner, with each level of pressurization not exceeding 10% of the working pressure. Each level of pressure is maintained for 30-60 seconds until it reaches 80% of the working pressure.

[0013] Pressure balancing stage: Maintain 80% of the working pressure for 2-3 minutes and observe the pressure decay. If the pressure fluctuation amplitude exceeds the critical threshold value ΔPmax of the pressure fluctuation amplitude, suspend pressurization and check the sealing system.

[0014] Final pressurization stage: gradually increase the pressure to the working pressure in increments of 5% of the working pressure, and maintain each pressure level for 1-2 minutes;

[0015] Pressure stabilization confirmation stage: After reaching the working pressure, maintain it for 3-5 minutes, and enter the subsequent test steps after confirming that the pressure fluctuation amplitude is less than the critical threshold value of the pressure fluctuation amplitude ΔPmax.

[0016] In one embodiment of the present invention, the step of applying periodic deflection motion to the sphere includes:

[0017] Starting from an initial 5° deflection angle, the deflection angle is increased by 1° after each movement cycle until it reaches a maximum deflection angle of 15°; then the deflection angle is reduced by 1° after each cycle until it returns to a 5° deflection angle, and this cycle repeats.

[0018] Starting from the initial frequency of 0.1Hz, after each complete angle increase and decrease cycle, the frequency is increased by 0.1Hz until it reaches the maximum frequency of 1Hz; then the frequency is reduced by 0.1Hz each cycle until it returns to 0.1Hz, and this cycle repeats;

[0019] Keep the angle and frequency gradients synchronized to ensure that the angle changes at each frequency are fully executed;

[0020] In each motion cycle, the current deflection angle and frequency parameters are recorded in real time and marked accordingly with the pressure fluctuation data.

[0021] In one embodiment of the present invention, a three-way conversion joint is connected to the outside of the pressure measuring hole, the first interface is connected to the inert gas injection pipeline, the second interface is connected to the pressure detection pipeline, and the third interface is connected to the pressure measuring hole. During the gas injection stage, the pressure detection pipeline is closed, and the gas injection pipeline is opened to inflate the sealing ring. After reaching the working pressure, the gas injection pipeline is closed and the pressure detection pipeline is opened to detect the change in the injected gas pressure value.

[0022] In one embodiment of the present invention, the step of recording the pressure fluctuation amplitude ΔP of the injected gas at a sampling frequency of not less than 10 Hz includes: collecting in real time at least 10 equally spaced pressure data points within each complete deflection cycle, and using the difference between the maximum pressure value and the minimum pressure value collected within the cycle as the pressure fluctuation amplitude ΔP corresponding to the deflection cycle.

[0023] In one embodiment of the present invention, the specific process of constructing the pressure fluctuation amplitude change curve ΔP(t) includes:

[0024] After the pressurization is stabilized, the pressure fluctuation amplitude data is continuously collected for at least 100 complete deflection cycles;

[0025] The collected pressure fluctuation amplitude data are arranged in chronological order, with each data point corresponding to a complete deflection cycle;

[0026] With time t as the abscissa and pressure fluctuation amplitude ΔP as the ordinate, connect adjacent data points with straight lines;

[0027] The broken line formed by the connection is smoothed to obtain a continuous ΔP(t) change curve;

[0028] During the curve construction process, abnormal fluctuation data points caused by equipment interference are eliminated.

[0029] In one embodiment of the present invention, the specific process of experimentally determining the critical pressure fluctuation amplitude threshold ΔPmax includes:

[0030] Prepare three groups of sealing ring samples of the same model and use different destructive test conditions:

[0031] The first group of samples was subjected to an intensive dynamic load with a deflection angle of 15-20° and a frequency of 1.2-1.5 Hz;

[0032] The second group of samples had axial vibration with an amplitude of 0.5-1mm superimposed on the 5-15° deflection motion;

[0033] The third group of samples were tested for sealing performance at an ambient temperature of 40-60°C;

[0034] For each group of samples, dry inert gas with the same working pressure is injected through the pressure measuring hole. The pressure fluctuation amplitude ΔP of each group of samples is continuously monitored at a sampling frequency of not less than 10 Hz. When a sample has visible leakage, the average ΔP value of the 10 complete deflection cycles before failure is recorded. The average ΔP values ​​of the three groups of samples are compared and the average value is taken as the ΔPmax critical threshold.

[0035] In one embodiment of the present invention, the circumferential strain of the sealing ring is also detected:

[0036] A distributed optical fiber strain sensing network is embedded inside the sealing ring, with multiple strain monitoring points evenly distributed along the circumference;

[0037] During the dynamic deflection test, the strain change data of each monitoring point is recorded in real time;

[0038] Identify the areas where the strain accumulation exceeds the circumferential average value and mark them as high stress concentration areas;

[0039] Determine the main impact direction of the fluid medium on the connector in the underwater environment, which is obtained through underwater photography or fluid dynamics analysis;

[0040] Adjust the installation orientation of the connector so that the high stress concentration area forms an angle of not less than 90° with the main impact direction of the medium;

[0041] Re-perform dynamic sealing test to verify the optimized strain distribution state.

[0042] In one embodiment of the present invention, a plurality of pressure measuring holes are provided at different positions of the flange, and sealing performance tests are performed simultaneously at the plurality of pressure measuring holes. The ΔP(t) variation curves of the pressure measuring holes are synthesized, and the average value is taken as the basis for life prediction.

[0043] To solve the above technical problems, the present invention further provides a system for testing the sealing performance of a spherical underwater connector, which is capable of executing the above method. The system comprises:

[0044] A gas injection module is used to inject dry inert gas into the sealing ring through the pressure measuring hole. The pressure of the inert gas is the same as the pressure of the spherical underwater connector when working underwater;

[0045] The dynamic loading module is used to apply periodic deflection motion to the sphere, causing it to deflect sinusoidally relative to the flange. The unidirectional deflection angle is set to 5-15° based on the statistical value of the maximum angular displacement of the pipeline joint under actual ocean current impact. The frequency is set to 0.1-1Hz based on the multiple acceleration coefficient of the typical ocean current vortex shedding frequency. The short-term extreme periodic deflection motion is used to simulate the dynamic working conditions of underwater pipelines subjected to long-term ocean current impact.

[0046] The pressure monitoring module is used to record the pressure fluctuation amplitude ΔP of the injected gas at a sampling frequency of not less than 10 Hz while applying the periodic deflection motion, record the pressure fluctuation amplitude ΔP0 of the first deflection motion cycle after pressurization is stabilized as the pressure fluctuation reference amplitude, and repeatedly measure the pressure fluctuation amplitude at regular intervals to obtain ΔPn;

[0047] The data processing module is used to construct a pressure fluctuation amplitude change curve ΔP(t) and calculate the duration of the increase from the initial reference value ΔP0 to ΔPmax based on the critical threshold value of the pressure fluctuation amplitude ΔPmax determined in advance through experiments, and output the predicted service life of the spherical underwater connector.

[0048] The above technical solution of the present invention has the following advantages over the prior art:

[0049] The method for testing the sealing performance of a spherical underwater connector described in the present invention first injects an inert gas matching the working pressure into the sealing ring to ensure that the test environment is consistent with the actual working conditions. Subsequently, a sinusoidal periodic deflection motion is applied to the sphere to simulate the dynamic load caused by ocean current impact. The deflection angle and frequency are both set based on real ocean data. The 5-15° deflection angle set based on the actual ocean current impact statistics can accurately reproduce the maximum angular displacement of the pipe joint in the long-term marine environment, ensuring that the mechanical stress to which the sealing ring is subjected is completely matched with the actual working conditions. At the same time, a multiple acceleration coefficient of the ocean current vortex shedding frequency is used to determine the test frequency of 0.1-1Hz, which not only ensures test efficiency but also avoids atypical failure modes caused by excessive acceleration. This parameter design enables short-term limit testing to equivalently simulate long-term actual service conditions, subjecting the sealing ring to the same alternating stress as in the actual working conditions. Through the sinusoidal wave deflection motion, the dynamic effect of the ocean current on the connector is accurately reproduced, so that the stress to which the sealing ring is subjected during the test is highly consistent with the actual service conditions, thereby improving the reliability of the test results.

[0050] While dynamically loading, the system records gas pressure fluctuations at a sampling frequency of at least 10 Hz, capturing microscopic leakage changes in the seal ring under cyclic loading. This data better reflects the cumulative effects of material fatigue than direct static testing of leaking gas. Static leak testing only measures the overall amount of gas lost, while this solution, by recording the amplitude of pressure fluctuations, can reflect the microscopic opening and closing changes of the sealing interface during dynamic deflection. When the seal ring develops microcracks or plastic deformation due to fatigue, its rebound performance decreases, resulting in more significant pressure fluctuations during the cyclic compression and release of gas. This increase in fluctuation amplitude indicates material degradation earlier and more sensitively than traditional leak rate testing, thus providing an early warning of seal performance degradation before macroscopic leakage occurs.

[0051] Finally, by analyzing the evolution trend of the pressure fluctuation amplitude and combining it with the critical threshold determined experimentally, a correlation model between the pressure fluctuation amplitude and the degradation of sealing performance was established. The predicted service life of the sealing ring from the initial state to failure can be calculated. For the first time, it is possible to infer the long-term service life from short-term test data, providing a scientific basis for preventive maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0053] Figure 1 It is a schematic structural diagram of an underwater connector to which the detection method of the present invention is applicable;

[0054] Figure 2 is a flowchart of the steps of the method for testing the sealing performance of a spherical underwater connector of the present invention;

[0055] Figure 3 This is a flow chart of the steps of injecting dry inert gas into the sealing ring through the pressure measuring hole of the present invention;

[0056] Figure 4 is a flow chart of the steps of applying periodic deflection motion to a sphere according to the present invention;

[0057] Figure 5 This is a flow chart of the steps of detecting the circumferential strain of the sealing ring introduced in the present invention;

[0058] Figure 6 It is a structural framework diagram of the system for testing the sealing performance of a spherical underwater connector according to the present invention.

[0059] Explanation of the accompanying drawings in the specification: 1. sphere; 2. flange; 3. sealing ring; 4. pressure measuring hole. DETAILED DESCRIPTION

[0060] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0061] The present invention discloses a method for detecting the sealing performance of a spherical underwater connector. Figure 1 As shown, the applicable spherical underwater connector includes a sphere 1 and a flange 2. The sphere 1 and the flange 2 are fitted together to form a seal through a sealing ring 3. A pressure measuring hole 4 is provided on the flange 2 and is connected to the sealing ring 3. Gas is introduced into the pressure measuring hole 4 to detect the sealing performance of the sealing ring 3. For example, Chinese utility model patent publication number CN216344531U discloses an elastic sealing ball flange, which belongs to a spherical underwater connector. As mentioned above, when testing the sealing performance of this type of spherical underwater connector, the existing technology introduces gas into the pressure measuring hole 4 of the flange 2 and determines whether the sealing ring 3 is properly installed or leaks by observing the flow of gas. Although this method can verify the installation quality, it can only reflect the current status and cannot evaluate the performance degradation trend of the sealing ring 3 under long-term dynamic loads. It ignores the problem that the sealing ring 3 is subjected to long-term alternating stress in actual working conditions. Due to the lack of dynamic simulation and long-term performance prediction methods, operation and maintenance personnel can only rely on regular inspections or passively wait for leaks to occur.

[0062] To solve the above problems, refer to Figure 2 As shown, the method of the present invention comprises the following steps:

[0063] Inject dry inert gas into the sealing ring 3 through the pressure measuring hole 4. The pressure of the injected inert gas is the same as the pressure of the spherical underwater connector when it is working underwater.

[0064] The key to this step is to restore the sealing environment under real working conditions. The use of inert gas (such as nitrogen) can avoid the corrosion interference of moisture or oxygen on the sealing material, ensuring that the test results only reflect the mechanical sealing performance. The gas pressure is set to the actual working water pressure, so that the sealing ring 3 is subjected to the same static compression force in the test as in actual service. This is the basis for subsequent dynamic testing. If the pressure is too low, the actual contact state of the sealing interface cannot be simulated; if it is too high, abnormal damage may be caused prematurely. This precise pressure matching ensures the comparability of test data with actual conditions.

[0065] A periodic deflection motion is applied to sphere 1, causing it to deflect sinusoidally relative to flange 2. The unidirectional deflection angle is set to 5-15° based on the statistical value of the maximum angular displacement of the pipeline joint under actual ocean current impact. The frequency is set to 0.1-1Hz based on the multiple acceleration coefficient of the typical ocean current vortex shedding frequency. The dynamic working condition of the underwater pipeline subjected to long-term ocean current impact is simulated through short-term extreme periodic deflection motion.

[0066] The core of this step is to reproduce the alternating stress that the sealing ring 3 is subjected to in the actual marine environment. The sinusoidal deflection simulates the pipeline swing characteristics caused by the periodic impact of ocean currents. Its parameter design is based on an in-depth study of the motion characteristics of pipeline joints under the impact of actual ocean currents: the deflection angle of 5 to 15 degrees covers the maximum angular displacement range of pipeline joints in most marine environments; and the frequency of 0.1-1 Hz corresponds to the accelerated simulation of the typical ocean current vortex shedding frequency. In the field of marine engineering, the typical ocean current vortex shedding frequency (that is, the frequency of periodic vortex shedding when water flows through cylindrical structures such as pipelines) is usually in the lower frequency band. According to the Strouhal number ( According to theoretical calculations, for underwater pipeline structures with a diameter of 0.1-1 meters, at a typical ocean current velocity of 1-2 m / s, the vortex shedding frequency is about 0.001-0.01 Hz (i.e., 0.06-0.6 cycles per minute). Although a single cycle of this low-frequency vortex shedding has little effect on the sealing ring 3, it can accumulate to millions of stress cycles during years or even decades of service, which is the main cause of fatigue failure of the sealing material. The 0.1-1 Hz test frequency used in this application is equivalent to a 100-fold acceleration factor compared to the actual vortex shedding frequency of 0.001-0.01 Hz. This acceleration ratio was set based on the following scientific considerations: First, a 100x acceleration factor makes a 24-hour laboratory test equivalent to approximately 100 days (approximately three months) of actual service time, ensuring test efficiency while avoiding atypical failure modes caused by excessively high frequencies. Second, the frequency range of 0.1-1Hz maintains the consistency of the fatigue mechanism of the sealing material. Studies have shown that the fatigue crack propagation behavior of rubber sealing materials at loading frequencies below 1Hz is essentially the same as that of quasi-static loading. This scientifically verified accelerated testing method can replicate the number of stress cycles experienced in long-term service in a short period of time while ensuring the authenticity of the mechanism.

[0067] Moreover, the sinusoidal motion pattern can produce uniform alternating stress, which is highly consistent with the periodic characteristics of real ocean currents. Through this precisely controlled dynamic loading, the stress type and number of cycles that the sealing ring 3 is subjected to during the test are highly consistent with the actual working conditions, making the accelerated test results truly representative.

[0068] While applying periodic deflection motion, record the pressure fluctuation amplitude ΔP of the injected gas at a sampling frequency of not less than 10 Hz. Record the pressure fluctuation amplitude ΔP0 of the first deflection motion cycle after pressurization is stabilized and use it as the pressure fluctuation reference amplitude. Repeat the pressure fluctuation amplitude measurement at regular intervals to obtain ΔPn, and construct the pressure fluctuation amplitude change curve ΔP(t).

[0069] High-frequency pressure sampling is the key to capturing microscopic failures of the sealing ring 3. A sampling rate of more than 10 Hz can fully record the dynamic changes in pressure within each deflection cycle (minimum 1 Hz), while the minute-level sampling of traditional static detection will miss this transient information. Recording the ΔP0 of the first cycle as a benchmark eliminates the influence of initial assembly deviations. Subsequently, through continuous monitoring of ΔPn, the gradual degradation of the elastic performance of the sealing ring 3 can be observed. The increase in the amplitude of pressure fluctuations directly reflects the decrease in resilience or microcrack propagation caused by fatigue at the sealing interface. This dynamic indicator is more sensitive to predicting early failure than the static leakage rate.

[0070] The critical threshold value ΔPmax of the pressure fluctuation amplitude is determined experimentally, and the duration of the increase from the initial reference value ΔP0 to ΔPmax is calculated based on the pressure fluctuation amplitude change curve ΔP(t), which is the predicted service life of the spherical underwater connector.

[0071] The critical threshold ΔPmax is calibrated through accelerated aging experiments, corresponding to the pressure fluctuation characteristics when the sealing ring 3 actually fails. By analyzing the growth rate of the ΔP(t) curve, the time T when ΔPmax is reached can be deduced, realizing a quantitative life prediction. The breakthrough of this method lies in correlating short-term test data with long-term performance: the dynamic pressure fluctuation amplitude includes both the instantaneous elastic response of the sealing material and the accumulated fatigue damage information. Its evolution law has a definite mathematical relationship with the service life. Compared with the traditional method of only judging "whether there is a leak", this solution can provide early warning of the trend of sealing performance degradation, provide a scientific basis for preventive maintenance, and avoid the risk of sudden failure.

[0072] Specifically, the method of the present invention elevates sealing detection from a static qualitative level to a dynamic quantitative level through the coordinated four steps of working condition restoration, dynamic loading, high-frequency monitoring and threshold determination. Through the dynamic indicator of pressure fluctuation amplitude, microscopic damage is identified before macroscopic leakage occurs, and a prediction model for short-term testing and long-term life is established, solving the industry problem that traditional methods cannot evaluate the degradation of sealing performance under alternating stress.

[0073] During the implementation process, if the working pressure gas is directly injected into the sealing ring 3, the sudden increase in pressure may cause the sealing ring 3 to deform too much instantaneously and affect the detection accuracy. To solve this problem, refer to Figure 3 As shown, a graded progressive pressurization scheme is proposed, including:

[0074] Pre-pressurization stage: A stepped pressurization method is adopted, with each level of pressurization controlled within 10% of the working pressure and maintained for 30-60 seconds. This progressive loading method allows the sealing ring 3 material to gradually adapt to pressure changes, avoiding microstructural damage caused by instantaneous stress concentration. At the same time, the 30-60 second maintenance time ensures that the creep of the sealing ring 3 is fully released;

[0075] Pressure stabilization and balance stage: When the pressure reaches 80% of the working pressure, maintaining a stable period of 2-3 minutes can effectively identify initial leaks in the sealing system. If the pressure fluctuation exceeds the ΔPmax threshold at this time, it indicates that there is an assembly defect or material damage on the sealing interface, and the test needs to be interrupted for maintenance. This design significantly improves the reliability of the detection process;

[0076] Final pressurization stage: Using a more precise 5% pressure increment, combined with a short hold time of 1-2 minutes, precise control is achieved when approaching the working pressure, ensuring pressure accuracy while avoiding excessively long test cycles.

[0077] Pressure stabilization confirmation stage: Through a final observation of 3-5 minutes, ensure that the system reaches a true steady state. At this time, the recorded pressure fluctuation reference value ΔP0 can truly reflect the initial performance status of the sealing ring 3.

[0078] This graded pressurization mechanism achieves a smooth transition of the stress state of the sealing ring 3 by controlling the pressure change rate and holding time, making the test data more reflective of the sealing performance under actual working conditions while avoiding false failure judgments caused by overload impact. The coordinated design of pressure parameters and time parameters at each stage takes into account both the mechanical properties of the material and the detection efficiency. In particular, the ΔPmax threshold is used as the judgment standard for each stage, forming a closed-loop quality control system.

[0079] During the implementation process, if the deflection motion with fixed angle and frequency is directly used for testing, it is difficult to fully evaluate the dynamic response characteristics of the sealing ring 3 under different working conditions. To solve this problem, refer to Figure 4 As shown, the present invention provides a progressive parameter-variable deflection motion solution, and the specific steps are as follows:

[0080] Angle gradient: Starting from an initial deflection angle of 5°, the deflection angle is increased by 1° after each movement cycle until it reaches a maximum of 15°, and then gradually reduced back to 5°. This gradual change method allows the sealing ring 3 material to gradually adapt to the increased mechanical stress and avoid instantaneous overload caused by sudden large-angle deflection;

[0081] Frequency gradient: The frequency starts from 0.1 Hz, increases by 0.1 Hz to 1 Hz after each complete angle cycle, and then gradually decreases. This design allows the viscoelastic response of the sealing ring 3 under different frequency loads to be fully examined.

[0082] Synchronous control: Synchronous gradients of angle and frequency ensure coordinated changes in test parameters. Each frequency stage fully covers the deflection angle range from minimum to maximum, allowing a comprehensive assessment of the performance of the seal 3 under various motion combinations.

[0083] Real-time monitoring: During the movement process, the current deflection parameters are recorded in real time and marked with corresponding pressure fluctuation data, establishing a complete working condition-response database, providing accurate input-output correspondence for subsequent analysis.

[0084] This progressive parameter-variation testing method, by gradually increasing the amplitude and frequency of the motion, accurately identifies the critical point of seal ring 3 performance degradation. The cyclical variation pattern examines the symmetry of the seal ring 3's response to increasing and decreasing loads. The synchronous and gradual parameter change design avoids data discontinuities caused by sudden changes in operating conditions. Real-time parameter recording ensures traceability and repeatability of test data. By simulating the complex and changing characteristics of ocean current impacts in actual operating conditions, this method enables test results to better reflect the seal ring 3's true service performance. In particular, it can detect progressive damage accumulation processes that are difficult to detect in fixed parameter testing, providing a more reliable data basis for service life prediction.

[0085] Specifically, when implementing the method of the present invention, it is necessary to simultaneously perform gas injection and pressure detection in the pressure measuring hole 4. For brand-new products, a pressure sensor can be set in the pressure measuring hole 4 for pressure detection when preparing the spherical underwater connector. However, the existing product does not have a corresponding pressure sensor set in the pressure measuring hole 4. In order to solve this problem, a pipeline switching scheme of a three-way conversion joint is proposed. When testing, a specially designed three-way conversion joint is connected to the pressure measuring hole 4 to physically separate the gas injection and pressure detection functions while maintaining system connectivity. The gas injection pipeline connected to the first interface is specifically used for inert gas delivery, the pressure detection pipeline connected to the second interface is dedicated to high-precision pressure monitoring, and the third interface is directly connected to the pressure measuring hole 4.

[0086] The operation mode of closing the pressure detection pipeline and opening the gas injection pipeline during the gas injection stage ensures that the gas flow during the inflation process will not impact or interfere with the pressure sensor. At the same time, the one-way flow design enables the sealing ring 3 to reach the working pressure state quickly and stably;

[0087] When the pressure reaches the set value, the working mode switches to closing the gas injection pipeline and opening the pressure detection pipeline. At this time, the static detection environment eliminates the fluid disturbance factor, and the pressure sensor can accurately capture the micro-pressure fluctuations generated by the sealing ring 3 during the dynamic deflection process.

[0088] The introduction of the three-way connector not only solves the problem of pressure detection, but also ensures that the gas flow during inflation will not impact or interfere with the pressure detection. This solution optimizes the detection process from a system level, so that the measurement results of the pressure fluctuation amplitude ΔP can more truly reflect the dynamic sealing performance of the sealing ring 3 itself, rather than the interference caused by the measurement system, providing a more reliable data basis for subsequent service life prediction.

[0089] Specifically, during the implementation process, it was found that if a simple continuous sampling method is used to record pressure fluctuations, it is difficult to accurately capture the dynamic impact of periodic deflection motion on sealing performance. To solve this problem, the present invention proposes a high-precision sampling scheme based on deflection cycle synchronization: by collecting no less than 10 equally spaced pressure data points in each complete deflection cycle, it is ensured that all phases of the sinusoidal deflection motion can be fully covered, and in particular, the pressure extremes at the two key positions of maximum and minimum deflection angles can be captured.

[0090] This equally spaced sampling design enables representative pressure distribution characteristics to be obtained in each deflection cycle. The difference between the maximum and minimum pressure values ​​within the cycle is used as the calculation method for ΔP, which effectively reflects the fluctuation amplitude of the sealing performance of the sealing ring 3 during the dynamic deformation process. The setting of a sampling frequency of not less than 10 Hz is based on the maximum frequency of the deflection movement of 1 Hz. This ensures that even at the fastest movement speed, sufficient data points can be collected in each cycle to accurately reconstruct the pressure waveform. The equally spaced sampling method avoids the loss of phase information that may be caused by random sampling, making the ΔP values ​​of different cycles comparable, and providing data consistency for constructing the ΔP(t) variation curve.

[0091] This periodically synchronized sampling strategy can effectively suppress the influence of non-periodic interference, highlight the pressure fluctuation characteristics directly related to the deflection motion, and make the test results more reflective of the true dynamic sealing performance of the sealing ring 3. By correlating the pressure fluctuation amplitude with the specific deflection period, a direct relationship between mechanical motion and sealing performance is established, providing reliable input parameters for the subsequent life prediction model.

[0092] During implementation, when collecting periodic pressure fluctuation data, the prediction results may be biased due to short-term data fluctuations and measurement noise interference. Therefore, to ensure data accuracy, sufficient data must be collected and possible interference data must be filtered out. In this embodiment, the specific process of constructing the pressure fluctuation amplitude change curve ΔP(t) includes:

[0093] After the pressurization stabilizes, continuously collect pressure fluctuation amplitude data for at least 100 complete deflection cycles. This data volume requirement ensures that the performance response of the sealing ring 3 under different deflection angle and frequency combinations can be covered, especially the progressive degradation characteristics of the sealing material under accelerated test conditions can be captured;

[0094] The design of strictly arranging the collected data in chronological order and ensuring that each data point corresponds to a complete deflection cycle maintains the temporal continuity and motion cycle integrity of the data, laying the foundation for the subsequent establishment of an accurate performance degradation timing model;

[0095] A coordinate system with time t as the horizontal axis and ΔP as the vertical axis is used, and adjacent data points are connected with straight lines to form a preliminary line graph. This processing method not only intuitively shows the overall trend of the pressure fluctuation amplitude changing with the test time, but also retains the key details of the original data.

[0096] The operation of smoothing the preliminary broken line effectively eliminates the interference of short-term random fluctuations through the intelligent filtering algorithm, so that the ΔP(t) variation curve can more clearly reflect the actual degradation trajectory of the performance of the sealing ring 3 without being interfered by measurement noise;

[0097] The abnormal data point elimination mechanism set up in the curve construction process can automatically identify and eliminate abnormal values ​​caused by instantaneous interference of equipment or operation fluctuations by setting a reasonable fluctuation threshold, ensuring that the curve reflects the actual performance variation of the sealing ring 3.

[0098] This systematic data processing method converts the raw pressure fluctuation data obtained from short-term accelerated tests into reliable performance degradation curves through multi-level quality control measures, providing a high-quality data foundation for subsequent calculations of the duration from ΔP0 to ΔPmax. This method pays special attention to maintaining the timing characteristics, cycle integrity, and trend stability of the accelerated test data, making the long-term service life prediction based on the extrapolation of short-term test data more accurate and reliable. It effectively solves the prediction bias problem caused by poor data quality in traditional methods and provides a scientific basis for preventive maintenance decisions for underwater connectors.

[0099] Specifically, the 100 test cycle data and life prediction analysis table constructed based on the above method are shown in Table 1:

[0100] Table 1:

[0101]

[0102] According to the above data, the pressure fluctuation amplitude change curve ΔP(t) is constructed as: ΔP(t) = 0.050 + 0.015·e^(0.0085·t). The failure threshold ΔPmax of the sealing ring 3 used in this test is tested through a destructive test: 0.20MPa. The predicted life is 320 cycles after calculation. Because the test frequency of 0.1-1Hz adopted in this application is equivalent to a 100-fold acceleration factor compared to the actual vortex shedding frequency of 0.001-0.01Hz, it is predicted that the life of the sealing ring 3 is 32,000 cycles. According to the time required for one test cycle, the life of the sealing ring 3 can be predicted.

[0103] Specifically, in order to make the critical pressure fluctuation amplitude threshold ΔPmax more accurate, this embodiment proposes a ΔPmax determination scheme with the synergistic effect of multiple factors. The specific process is as follows:

[0104] Three groups of identical seal ring 3 samples were prepared and subjected to different destructive test conditions. The first group employed an enhanced dynamic load with a deflection angle of 15-20° and a frequency of 1.2-1.5Hz. This overload test accelerates the initiation and propagation of fatigue cracks in the seal ring 3, simulating the mechanical stresses of extreme marine environments.

[0105] The second group superimposed axial vibration with an amplitude of 0.5-1mm on the standard deflection motion to reproduce the multi-directional composite vibration load commonly found in actual working conditions, specifically targeting the fretting wear effect at the interface between the seal ring 3 and the flange 2;

[0106] The third group was tested at an ambient temperature of 40-60°C to examine the effect of temperature on the elastic modulus and creep properties of the sealing material.

[0107] Each group of samples is injected with dry inert gas at the same working pressure through pressure measuring hole 4 to ensure the consistency of pressure conditions. At the same time, the pressure fluctuation amplitude ΔP is continuously monitored at a sampling frequency of not less than 10 Hz. This high-frequency monitoring can accurately capture the microscopic leakage characteristics before seal failure. When a sample has a visible leak, the average ΔP value of the 10 complete deflection cycles before failure is recorded. This design not only avoids the randomness of a single measurement, but also reflects the progressive degradation process of sealing performance. Finally, the average ΔP values ​​of the three groups of samples are compared and the average is taken as the ΔPmax critical threshold. This multi-condition comprehensive judgment method effectively improves the reliability of the threshold, so that the determined ΔPmax value can cover the influence of different failure modes.

[0108] This solution solves the problem of threshold judgment deviation that may be caused by traditional single-factor testing by constructing a multi-dimensional failure test system. In particular, it overcomes the prediction error caused by the difference between laboratory conditions and actual working conditions. The scientific combination of three sets of test conditions not only takes into account the rapid failure under extreme loads, but also includes the synergistic effects of composite vibration and temperature aging, so that the obtained ΔPmax threshold has a wider range of working condition adaptability and a longer prediction validity period.

[0109] During the implementation process, it was found that it was difficult to fully evaluate the local stress distribution characteristics of the sealing ring 3 during dynamic deflection by relying solely on pressure fluctuation monitoring, especially the inability to identify the potential failure risk caused by circumferential uneven deformation. To solve this problem, reference was made to Figure 5 As shown, this embodiment further introduces a technical solution for detecting the circumferential strain of the sealing ring 3, which specifically includes the following steps:

[0110] By embedding a distributed optical fiber strain sensing network inside the seal ring 3, strain monitoring points are evenly distributed along the circumference at intervals of no more than 10 degrees, forming a high-density strain monitoring array. This embedded sensing design can capture the microscopic deformation characteristics of various areas inside the seal ring 3 in real time without affecting the sealing performance.

[0111] During the dynamic deflection test, the fiber optic sensing network synchronously records the strain change data of each monitoring point at a sampling frequency of no less than 50Hz, ensuring that the strain response at each phase of the sinusoidal deflection motion can be fully recorded, especially the maximum strain state at the extreme deflection position;

[0112] By processing and analyzing full circumferential strain data in real time, the system can accurately identify areas where the accumulated strain exceeds the circumferential average. These high stress concentration areas are often the starting points for fatigue crack initiation in the seal ring 3 and are also the key areas that will first fail in long-term use.

[0113] Combined with the fluid scouring traces recorded by the underwater camera system or the mainstream impact direction obtained by computational fluid dynamics (CFD) simulation, the spatial correspondence between the stress distribution of the sealing ring 3 and the external load is established;

[0114] Based on this correspondence, the connector's installation orientation is adjusted so that the identified high-stress concentration area forms a safety angle of no less than 90° with the main impact direction of the medium. This optimized arrangement allows the weakest area of ​​the sealing ring 3 to avoid the maximum fluid impact load, achieving balanced stress distribution.

[0115] Finally, the optimization effect was verified by re-performing dynamic sealing tests to ensure that the strain distribution state was effectively improved while the pressure fluctuation amplitude ΔP remained within a safe range.

[0116] This technical solution combines optical fiber strain monitoring with pressure fluctuation detection to comprehensively evaluate the performance of the sealing ring 3 from two dimensions: micro-deformation and macro-sealing. In particular, it achieves the best "stress-load" match through optimization of the installation orientation, making the wear rate of each area of ​​the sealing ring 3 consistent, significantly extending the overall service life.

[0117] Specifically, due to the uneven circumferential force on the sealing ring 3 and possible local defects, the pressure fluctuation data of a single pressure measuring point is difficult to fully reflect the overall sealing performance. Therefore, the existing spherical underwater connector is provided with at least two symmetrically arranged pressure measuring holes 4. For multiple pressure measuring holes 4, this embodiment further proposes a solution for coordinated detection of multiple pressure measuring holes 4:

[0118] According to the number of pressure measuring holes 4 in the circumferential direction of the flange 2, inert gas of the same pressure is synchronously injected into each pressure measuring hole 4 through a multi-channel gas control system to ensure that the initial conditions of each detection point are consistent. During the dynamic deflection test, each pressure measuring hole 4 independently collects pressure fluctuation data and generates a ΔP(t) change curve. This multi-point synchronous monitoring can effectively identify the local weak links in the sealing ring 3. After integrating the ΔP(t) change curves of each pressure measuring hole 4, the average value is taken as the basis for life prediction. This embodiment improves the statistical significance of the test results through data fusion of multiple pressure measuring holes 4, so that the life prediction model is established on the basis of more comprehensive performance data, avoiding prediction deviations caused by randomness of measurement positions.

[0119] Reference Figure 6 As shown, in order to implement the above method, the present invention also discloses a system for detecting the sealing performance of a spherical underwater connector, which can execute the method, and the system includes:

[0120] A gas injection module is used to inject dry inert gas into the sealing ring 3 through the pressure measuring hole 4. The pressure of the inert gas is the same as the pressure of the spherical underwater connector when it is working underwater;

[0121] The dynamic loading module is used to apply periodic deflection motion to the sphere 1, causing it to deflect sinusoidally relative to the flange 2. The unidirectional deflection angle is set to 5-15° based on the statistical value of the maximum angular displacement of the pipeline joint under actual ocean current impact. The frequency is set to 0.1-1Hz based on the multiple acceleration coefficient of the typical ocean current vortex shedding frequency. The short-term extreme periodic deflection motion is used to simulate the dynamic working conditions of the underwater pipeline subjected to long-term ocean current impact.

[0122] The pressure monitoring module is used to record the pressure fluctuation amplitude ΔP of the injected gas at a sampling frequency of not less than 10 Hz while applying the periodic deflection motion, record the pressure fluctuation amplitude ΔP0 of the first deflection motion cycle after pressurization is stabilized as the pressure fluctuation reference amplitude, and repeatedly measure the pressure fluctuation amplitude at regular intervals to obtain ΔPn;

[0123] The data processing module is used to construct a pressure fluctuation amplitude change curve ΔP(t) and calculate the duration of the increase from the initial reference value ΔP0 to ΔPmax based on the critical threshold value of the pressure fluctuation amplitude ΔPmax determined in advance through experiments, and output the predicted service life of the spherical underwater connector.

[0124] The system for testing the sealing performance of a spherical underwater connector of this embodiment can realize the testing of the sealing performance of the spherical underwater connector in the above embodiment. The specific implementation process refers to the description of the above embodiment and will not be repeated here.

[0125] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0126] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for testing the sealing performance of a spherical underwater connector. The spherical underwater connector includes a sphere and a flange. The sphere and flange are sealed together by a sealing ring. The flange is provided with a pressure measuring hole that penetrates the sealing ring. Gas is passed through the pressure measuring hole to test the sealing performance of the sealing ring. The method is characterized by: The method comprises the following steps: Inject dry inert gas into the sealing ring through the pressure measuring hole. The pressure of the injected inert gas is the same as the pressure of the spherical underwater connector when working underwater. The steps of injecting dry inert gas into the sealing ring through the pressure measuring hole include: pre-pressurization stage: inject inert gas into the pressure measuring hole in a step-by-step pressurization manner, with the pressurization amplitude of each stage not exceeding 10% of the working pressure, and each stage of pressure is maintained for 30-60 seconds until it reaches 80% of the working pressure; pressure balancing stage: maintain at 80% of the working pressure for 2-3 minutes, observe the pressure attenuation, and if the pressure fluctuation amplitude exceeds the critical threshold value ΔPmax of the pressure fluctuation amplitude, suspend pressurization and check the sealing system; final pressurization stage: gradually increase the pressure to the working pressure in increments of 5% of the working pressure, and maintain each stage of pressure for 1-2 minutes; pressure stabilization confirmation stage: maintain for 3-5 minutes after reaching the working pressure, and enter the subsequent test steps after confirming that the pressure fluctuation amplitude is less than the critical threshold value ΔPmax of the pressure fluctuation amplitude; A periodic deflection motion is applied to the sphere, causing it to deflect sinusoidally relative to the flange. The unidirectional deflection angle is set to 5-15° based on the statistical value of the maximum angular displacement of the pipeline joint under actual ocean current impact. The frequency is set to 0.1-1Hz based on the multiple acceleration coefficient of the typical ocean current vortex shedding frequency. The dynamic working conditions of the underwater pipeline subjected to long-term ocean current impact are simulated through short-term extreme periodic deflection motion. While applying periodic deflection motion, record the pressure fluctuation amplitude ΔP of the injected gas at a sampling frequency of not less than 10 Hz. Record the pressure fluctuation amplitude ΔP0 of the first deflection motion cycle after pressurization is stabilized and use it as the pressure fluctuation reference amplitude. Repeat the pressure fluctuation amplitude measurement at regular intervals to obtain ΔPn, and construct the pressure fluctuation amplitude change curve ΔP(t). The critical threshold value ΔPmax of the pressure fluctuation amplitude is determined experimentally, and the duration of the increase from the initial reference value ΔP0 to ΔPmax is calculated according to the pressure fluctuation amplitude change curve ΔP(t), which is the predicted service life of the spherical underwater connector.

2. The method for testing the sealing performance of a spherical underwater connector according to claim 1, characterized in that: The steps for applying periodic deflection motion to the sphere include: Starting from an initial 5° deflection angle, the deflection angle is increased by 1° after each movement cycle until it reaches a maximum deflection angle of 15°; then the deflection angle is reduced by 1° after each cycle until it returns to a 5° deflection angle, and this cycle repeats. Starting from the initial frequency of 0.1Hz, after each complete angle increase and decrease cycle, the frequency is increased by 0.1Hz until it reaches the maximum frequency of 1Hz; then the frequency is reduced by 0.1Hz each cycle until it returns to 0.1Hz, and this cycle repeats; Keep the angle and frequency gradients synchronized to ensure that the angle changes at each frequency are fully executed; In each motion cycle, the current deflection angle and frequency parameters are recorded in real time and marked accordingly with the pressure fluctuation data.

3. The method for testing the sealing performance of a spherical underwater connector according to claim 1, characterized in that: A three-way conversion joint is connected to the outside of the pressure measuring hole. The first interface is connected to the inert gas injection pipeline, the second interface is connected to the pressure detection pipeline, and the third interface is connected to the pressure measuring hole. During the gas injection stage, the pressure detection pipeline is closed and the gas injection pipeline is opened to inflate the sealing ring. After reaching the working pressure, the gas injection pipeline is closed and the pressure detection pipeline is opened to detect the changes in the injected gas pressure value.

4. The method for testing the sealing performance of a spherical underwater connector according to claim 3, characterized in that: The step of recording the pressure fluctuation amplitude ΔP of the injected gas at a sampling frequency of not less than 10 Hz includes: collecting in real time at least 10 equally spaced pressure data points within each complete deflection cycle, and using the difference between the maximum pressure value and the minimum pressure value collected within the cycle as the pressure fluctuation amplitude ΔP corresponding to the deflection cycle.

5. The method for testing the sealing performance of a spherical underwater connector according to claim 1, characterized in that: The specific process of constructing the pressure fluctuation amplitude change curve ΔP(t) includes: After the pressurization is stabilized, the pressure fluctuation amplitude data is continuously collected for at least 100 complete deflection cycles; The collected pressure fluctuation amplitude data are arranged in chronological order, with each data point corresponding to a complete deflection cycle; With time t as the abscissa and pressure fluctuation amplitude ΔP as the ordinate, connect adjacent data points with straight lines; The broken line formed by the connection is smoothed to obtain a continuous ΔP(t) change curve; During the curve construction process, abnormal fluctuation data points caused by equipment interference are eliminated.

6. The method for testing the sealing performance of a spherical underwater connector according to claim 1, characterized in that: The specific process of experimentally determining the critical threshold value ΔPmax of the pressure fluctuation amplitude includes: Prepare three groups of sealing ring samples of the same model and use different destructive test conditions: The first group of samples was subjected to an intensive dynamic load with a deflection angle of 15-20° and a frequency of 1.2-1.5 Hz; The second group of samples had axial vibration with an amplitude of 0.5-1mm superimposed on the 5-15° deflection motion; The third group of samples were tested for sealing performance at an ambient temperature of 40-60°C; For each group of samples, dry inert gas with the same working pressure is injected through the pressure measuring hole. The pressure fluctuation amplitude ΔP of each group of samples is continuously monitored at a sampling frequency of not less than 10 Hz. When a sample has visible leakage, the average ΔP value of the 10 complete deflection cycles before failure is recorded. The average ΔP values ​​of the three groups of samples are compared and the average value is taken as the ΔPmax critical threshold.

7. The method for testing the sealing performance of a spherical underwater connector according to claim 1, characterized in that: It also includes circumferential strain detection of the sealing ring: A distributed optical fiber strain sensing network is embedded inside the sealing ring, with multiple strain monitoring points evenly distributed along the circumference; During the dynamic deflection test, the strain change data of each monitoring point is recorded in real time; Identify the areas where the strain accumulation exceeds the circumferential average value and mark them as high stress concentration areas; Determine the main impact direction of the fluid medium on the connector in the underwater environment, which is obtained through underwater photography or fluid dynamics analysis; Adjust the installation orientation of the connector so that the high stress concentration area forms an angle of not less than 90° with the main impact direction of the medium; Re-perform dynamic sealing test to verify the optimized strain distribution state.

8. The method for testing the sealing performance of a spherical underwater connector according to claim 1, characterized in that: A plurality of pressure measuring holes are provided at different positions of the flange, and sealing performance tests are performed simultaneously at the plurality of pressure measuring holes. The ΔP(t) variation curves of the pressure measuring holes are synthesized, and the average value is taken as the basis for life prediction.

9. A system for testing the sealing performance of a spherical underwater connector, capable of executing the method according to any one of claims 1 to 8, characterized in that: The system comprises: A gas injection module is used to inject dry inert gas into the sealing ring through the pressure measuring hole. The pressure of the inert gas is the same as the pressure of the spherical underwater connector when working underwater; The dynamic loading module is used to apply periodic deflection motion to the sphere, causing it to deflect sinusoidally relative to the flange. The unidirectional deflection angle is set to 5-15° based on the statistical value of the maximum angular displacement of the pipeline joint under actual ocean current impact. The frequency is set to 0.1-1Hz based on the multiple acceleration coefficient of the typical ocean current vortex shedding frequency. The short-term extreme periodic deflection motion is used to simulate the dynamic working conditions of underwater pipelines subjected to long-term ocean current impact. The pressure monitoring module is used to record the pressure fluctuation amplitude ΔP of the injected gas at a sampling frequency of not less than 10 Hz while applying the periodic deflection motion, record the pressure fluctuation amplitude ΔP0 of the first deflection motion cycle after pressurization is stabilized as the pressure fluctuation reference amplitude, and repeatedly measure the pressure fluctuation amplitude at regular intervals to obtain ΔPn; The data processing module is used to construct a pressure fluctuation amplitude change curve ΔP(t) and calculate the duration of the increase from the initial reference value ΔP0 to ΔPmax based on the critical threshold value of the pressure fluctuation amplitude ΔPmax determined in advance through experiments, and output the predicted service life of the spherical underwater connector.

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