Air pressure abnormity monitoring method of inflatable film structure for distinguishing temperature change and gas leakage

Abstract

The invention belongs to the technical field of inflatable film structure health monitoring and state evaluation, and provides an inflatable film structure air pressure abnormity monitoring method for distinguishing environment temperature change and gas leakage. According to the method, firstly, under the conditions that the structure is well sealed and gas leakage does not exist, a finite element analysis model of the inflatable film structure is established and corrected through measured data, theoretical values of internal air pressure of the structure under different temperature working conditions are obtained, then a temperature-air pressure mapping relation is established, and a theoretical air pressure calculation module is formed; in the actual operation process of the structure, internal temperature and air pressure data are collected in real time, a theoretical air pressure value under the corresponding temperature condition is obtained based on the theoretical air pressure calculation module, the theoretical air pressure value is compared with actually-measured air pressure, and air pressure deviation is calculated; by setting the air pressure deviation threshold value and the time window, the air pressure deviation value and the continuity of the air pressure deviation value are jointly judged, so that normal air pressure fluctuation caused by environment temperature change and abnormal air pressure change caused by gas leakage are effectively distinguished, and accurate recognition and early warning of tiny leakage of the inflatable film structure are achieved. According to the invention, the risk of misjudgment caused by temperature interference can be reduced, and the reliability and safety of air pressure monitoring of the inflatable film structure are improved.

Description

Technical Field

[0001] This invention belongs to the technical field of health monitoring and status assessment of inflatable membrane structures, and relates to a method for determining whether changes in internal air pressure of an inflatable membrane structure are caused by air leakage under varying ambient temperature conditions. Background Technology

[0002] Inflatable membrane structures are lightweight structural forms that rely on internal gas pressure to maintain their shape and load-bearing capacity. They offer advantages such as light weight, foldability, and ease of deployment, and are widely used in temporary buildings, engineering protection, and aerospace deployable structures. After inflation, the stability of the internal gas pressure significantly impacts the structure's operational safety. In actual use, the ambient temperature of the inflatable membrane structure often changes over time, altering the temperature of the structure and its internal gas, thus causing changes in internal gas pressure. These pressure fluctuations caused by temperature changes are normal physical phenomena and do not indicate structural abnormalities. However, during long-term service, inflatable membrane structures may experience gas leaks due to minor external damage or other reasons, especially early minor leaks. These leaks cause small pressure changes that can easily overlap with temperature-induced pressure fluctuations, making them difficult to distinguish. Existing pressure monitoring methods often employ real-time measurement and fixed threshold judgment, typically failing to fully consider the combined effects of environmental and structural temperature changes on internal gas pressure, leading to false alarms or missed alarms. Existing studies have attempted to obtain the pressure variation patterns of inflatable membrane structures under different temperature conditions through long-term operational monitoring or experimental testing. However, such methods usually require a long time to cover the temperature range that the structure may experience during actual service, and it is difficult to obtain complete and reliable data during the initial deployment or short-term operation phase of the structure. At the same time, some extreme or rare temperature conditions have a low probability of occurrence in the actual environment or are expensive to achieve experimentally, making it difficult to fully reflect the impact of temperature changes on internal pressure by relying solely on measured data.

[0003] Therefore, when environmental temperature changes and minor gas leaks in the structure may coexist, there is an urgent need for a method that can establish a reliable pressure benchmark and distinguish the causes of pressure changes, so as to accurately identify and provide early warning of abnormal gas leaks in inflatable membrane structures. Summary of the Invention

[0004] To address the problem in existing technologies that make it difficult to accurately distinguish the causes of internal air pressure changes in inflatable membrane structures when both ambient temperature changes and minor gas leaks occur simultaneously, leading to misjudgments or missed detections, this invention proposes a method for monitoring abnormal air pressure in inflatable membrane structures that distinguishes between temperature changes and gas leaks.

[0005] This invention establishes and modifies a finite element analysis model of an inflatable membrane structure to obtain the theoretical air pressure response law under different temperature conditions in the absence of leakage. During the actual operation of the structure, the real-time monitored air pressure is compared and analyzed with the theoretical air pressure to effectively distinguish between normal air pressure fluctuations caused by temperature changes and abnormal air pressure changes caused by gas leakage. This enables automatic identification and early warning of minor leaks in the inflatable membrane structure, thereby improving the safety and reliability of the structure's operation.

[0006] To achieve the above objectives, the technical solution of the present invention is: a method for monitoring abnormal air pressure in an inflatable membrane structure that distinguishes between temperature changes and gas leaks, comprising the following steps:

[0007] Step 1 includes: In ANSYS APDL modeling software, based on the actual structure of the inflatable membrane structure, establishing the geometry of the inflatable membrane and creating air inside it, and defining the corresponding material properties; wherein, the geometric dimension parameters include the external dimensions of the membrane structure, the membrane thickness and the size of the air, and the material property parameters include the elastic modulus, Poisson's ratio and density of the membrane material, and the density, sound velocity and air pressure parameters of the gas.

[0008] Step 2 includes: Assuming the structure is perfectly sealed and free of gas leakage, multiple sets of measured temperature values ​​and corresponding measured gas pressure values ​​are acquired inside the structure using temperature and pressure sensors. The measured values ​​are taken under various operating conditions as much as possible. The measured gas pressure values ​​are compared with the theoretical gas pressure values ​​calculated by the finite element model under the same temperature conditions. If a discrepancy exists, at least one equivalent parameter in the finite element model is corrected, and the calculation and analysis are re-performed based on the corrected parameters until the finite element model calculation results match the measured results. The equivalent parameters include one or more of the following: structural equivalent volume parameters, initial gas pressure parameters, and gas thermal parameters.

[0009] Step 3 includes: determining the temperature variation range of the inflatable membrane structure under normal service conditions based on its actual operating environment and possible ambient temperature changes; selecting each temperature condition at 0.1 degrees Celsius intervals within the temperature variation range, and calculating and analyzing each temperature condition based on the modified air pressure prediction model while keeping the structure in a leak-free state, to obtain the theoretical air pressure value under the corresponding temperature conditions; organizing and summarizing the theoretical air pressure results obtained under different temperature conditions to form a temperature-pressure response reference dataset for characterizing the relationship between temperature changes and internal air pressure changes, thereby revealing the influence of temperature factors on the internal air pressure changes of the inflatable membrane structure under leak-free conditions.

[0010] Step 4 includes: processing the temperature-pressure response reference data obtained in Step 3, and constructing a mapping relationship between temperature and theoretical pressure through table lookup, interpolation, and function fitting; integrating the mapping relationship into the theoretical pressure calculation module, so that the theoretical pressure calculation module can quickly and accurately output the corresponding theoretical pressure prediction value under the condition of inputting the current temperature parameters of the inflatable membrane structure.

[0011] The theoretical pressure calculation module can be set as an independent software function module, or embedded as a sub-module into the structural health monitoring system or the host computer monitoring system. The module can interact with the data acquisition modules of the temperature sensor and the pressure sensor to realize the automatic reading of real-time monitored temperature data and output the corresponding theoretical pressure prediction results, providing a basic input for subsequent pressure anomaly identification and early warning.

[0012] Step 5 includes: synchronously collecting internal temperature and pressure data of the structure at a preset sampling frequency using temperature sensors and air pressure sensors installed inside the inflatable membrane structure, and transmitting the data to the monitoring and analysis system.

[0013] Step 6 includes: during the actual operation of the inflatable membrane structure, real-time acquisition of the internal temperature T of the structure. real (t) and air pressure P real Based on the real-time temperature data, the monitoring data of (t) is used to call the theoretical pressure calculation module established in step 4 to calculate the corresponding theoretical pressure value P. theo (t); Subsequently, the theoretical air pressure is compared with the actual measured air pressure, and the relative air pressure deviation value ΔP is calculated. rel (t).

[0014]

[0015] Where t is the real-time monitoring time, and the relative deviation ΔP rel (t) is a percentage indicator used to consider changes in structural air pressure, which facilitates the determination of a unified threshold under different pressure levels. Through the above calculation, the deviation of the internal air pressure of the inflatable membrane structure from the theoretical expected value can be evaluated in real time, providing a quantitative basis for subsequent air pressure anomaly determination and leakage early warning.

[0016] Step 7 includes: based on the pressure stability requirements of the inflatable membrane structure and the time resolution of the monitoring system, pre-setting the time window length Δt for pressure anomaly detection and the pressure deviation threshold ΔP. th During real-time monitoring, the pressure deviation sequence ΔP calculated in step 6 is analyzed. rel (t) Perform continuous-time statistical analysis and determine whether the air pressure deviation meets the following criterion within each time window: when the air pressure deviation ΔP is within the time window Δt.rel (t) exceeds the pressure deviation threshold ΔP at certain times. th However, if the duration is less than the length of the time window, the abnormal air pressure is determined to be a transient abnormality caused by rapid fluctuations in ambient temperature, external disturbances, or measurement noise. No gas leak warning is triggered, and only the abnormal event is recorded. When the air pressure deviation exceeds the air pressure deviation threshold continuously within the continuous time window Δt, it is determined that the air pressure change inside the inflatable membrane structure can no longer be explained by normal temperature effects, and the structure is identified as having a risk of abnormal air pressure caused by gas leakage.

[0017] When a structural system is identified as having a risk of abnormal air pressure due to gas leakage, the system automatically outputs an abnormal air pressure warning. The warning information may include the time of the abnormality, the magnitude of the air pressure deviation, the duration, and the level of leakage risk. It can also be sent to the structural health monitoring system or the host computer monitoring platform to prompt maintenance personnel to take timely inspection or disposal measures. Attached Figure Description

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0019] Figure 1 This is a flowchart of a method for monitoring abnormal air pressure in an inflatable membrane structure that distinguishes between temperature changes and gas leaks, according to the present invention.

[0020] Figure 2 This is a finite element model diagram of an inflatable thin film structure.

[0021] Figure 3 This is a diagram showing the air pressure results obtained from the finite element model analysis. Detailed Implementation

[0022] The following detailed embodiments further illustrate the method for monitoring abnormal air pressure in an inflatable membrane structure that distinguishes between temperature changes and gas leaks, as proposed in this invention. These embodiments are merely illustrative of the technical solution of this invention and do not constitute a limitation on the scope of protection of this invention. Various modifications or substitutions can be made by those skilled in the art without departing from the technical concept of this invention, and all such modifications or substitutions should fall within the scope of protection of this invention.

[0023] Step 1: In ANSYS APDL modeling software, based on the actual structure of the inflatable membrane structure, use Shell281 elements to create the membrane, use Fluid220 elements to create the air, set the temperature field, and define the corresponding material properties. The geometric parameters include the external dimensions of the membrane structure, the membrane thickness, and the air volume. The material property parameters include the elastic modulus, Poisson's ratio, and density of the membrane material, and the density, sound velocity, and air pressure parameters of the gas. Then, mesh the model, perform fluid-structure interaction (FSI) analysis, and establish the finite element model as shown below. Figure 2 As shown.

[0024] Step 2: Temperature and pressure sensors are installed inside the inflatable membrane structure. Assuming the structure is perfectly sealed and leak-free, multiple sets of measured temperature values ​​and corresponding measured pressure values ​​are acquired using the temperature and pressure sensors. Based on the finite element model from Step 1, the temperature of the finite element model is set according to the measured temperatures, and the theoretical pressure value at the corresponding temperature is obtained through analysis. Figure 3 To obtain the model pressure result from the finite element software analysis, the measured pressure value is compared with the theoretical pressure value calculated by the finite element model under the same temperature conditions. When there is a deviation between the two, one or more equivalent parameters of the structural equivalent volume parameters, initial pressure parameters, and gas thermal parameters in the finite element analysis model are corrected, and the calculation and analysis are re-performed based on the corrected parameters until the calculation result of the finite element model is consistent with the measured result.

[0025] Step 3: Based on the actual operating environment of the inflatable membrane structure and the possible environmental temperature changes it may experience, determine the temperature variation range of the structure under normal service conditions. Within the temperature variation range, select each temperature condition at 0.1 degrees Celsius intervals. Under the premise of keeping the structure in a gas-leakage-free state, calculate and analyze each temperature condition based on the modified air pressure prediction model to obtain the theoretical air pressure value under the corresponding temperature conditions. Organize and summarize the theoretical air pressure results obtained under different temperature conditions to form a temperature-pressure response reference dataset to characterize the relationship between temperature change and internal air pressure change, thereby revealing the influence of temperature factors on the internal air pressure change of the inflatable membrane structure under leak-free conditions.

[0026] Step 4: Based on the temperature-pressure response reference data obtained in Step 3, process the reference data and construct the mapping relationship between temperature and theoretical pressure through table lookup, interpolation, and function fitting; integrate the mapping relationship into the theoretical pressure calculation module so that the theoretical pressure calculation module can quickly and accurately output the corresponding theoretical pressure prediction value under the condition of inputting the current temperature parameters of the inflatable membrane structure.

[0027] The theoretical pressure calculation module can be set as an independent software function module, or embedded as a sub-module into the structural health monitoring system or the host computer monitoring system. The module can interact with the data acquisition modules of the temperature sensor and the pressure sensor to realize the automatic reading of real-time monitored temperature data and output the corresponding theoretical pressure prediction results, providing a basic input for subsequent pressure anomaly identification and early warning.

[0028] Step 5 includes: using temperature sensors and air pressure sensors installed inside the inflatable membrane structure to synchronously collect internal temperature and air pressure data in real time at a preset sampling frequency, and transmitting the data to the monitoring and analysis system.

[0029] Step 6 includes: during the actual operation of the inflatable membrane structure, real-time acquisition of the internal temperature T of the structure. real (t) and air pressure P real Based on the real-time temperature data, the monitoring data of (t) is used to call the theoretical pressure calculation module established in step 4 to calculate the corresponding theoretical pressure value P. theo (t); Subsequently, the theoretical air pressure is compared with the actual measured air pressure, and the relative air pressure deviation value ΔP is calculated. rel (t).

[0030]

[0031] Where t is the real-time monitoring time, and the relative deviation ΔP rel (t) is a percentage indicator used to consider changes in structural air pressure, which facilitates the determination of a unified threshold under different pressure levels. Through the above calculation, the deviation of the internal air pressure of the inflatable membrane structure from the theoretical expected value can be evaluated in real time, providing a quantitative basis for subsequent air pressure anomaly determination and leakage early warning.

[0032] Step 7 includes: based on the pressure stability requirements of the inflatable membrane structure and the time resolution of the monitoring system, pre-setting the time window length Δt for pressure anomaly detection and the pressure deviation threshold ΔP. th The time window length Δt is set to 1 minute, and the air pressure deviation threshold ΔP is set to... th The value is set to 5%. During real-time monitoring, the pressure deviation sequence ΔP calculated in step 6 is... rel (t) Perform continuous-time statistical analysis and determine whether the air pressure deviation meets the following criterion within each time window: when the air pressure deviation ΔP is within the time window Δt. rel (t) exceeds the pressure deviation threshold ΔP at certain times. thHowever, if the duration is less than the length of the time window, the abnormal air pressure is determined to be a transient abnormality caused by rapid fluctuations in ambient temperature, external disturbances, or measurement noise. No gas leak warning is triggered, and only the abnormal event is recorded. When the air pressure deviation exceeds the air pressure deviation threshold continuously within the continuous time window Δt, it is determined that the air pressure change inside the inflatable membrane structure can no longer be explained by normal temperature effects, and the structure is identified as having a risk of abnormal air pressure caused by gas leakage.

[0033] When a structural system is identified as having a risk of abnormal air pressure due to gas leakage, the system automatically outputs an abnormal air pressure warning. The warning information may include the time of the abnormality, the magnitude of the air pressure deviation, the duration, and the level of leakage risk. It can also be sent to the structural health monitoring system or the host computer monitoring platform to prompt maintenance personnel to take timely inspection or disposal measures.

Claims

1. A method for monitoring abnormal air pressure in an inflatable membrane structure, distinguishing between temperature changes and gas leaks, characterized in that, Includes the following steps: Step 1: Under conditions of no gas leakage, establish a finite element analysis model of the inflatable membrane structure based on the actual inflatable membrane structure; Step 2: After confirming that the inflatable membrane structure is in a state of no gas leakage, collect the actual internal air pressure and temperature data of the inflatable membrane structure under at least one temperature condition, and compare the actual internal air pressure with the corresponding theoretical air pressure obtained by the finite element analysis model. Based on the comparison results, correct the parameters of the finite element analysis model to obtain the corrected air pressure prediction model. Step 3: Based on the modified air pressure prediction model, analyze the internal air pressure response of the inflatable membrane structure under different temperature conditions, and obtain reference data reflecting the relationship between temperature change and air pressure change; Step 4: Based on the reference data, construct a theoretical pressure calculation module to obtain the corresponding theoretical pressure value under known structural temperature conditions; Step 5: During the actual operation of the inflatable membrane structure, real-time monitoring data of the internal temperature and air pressure of the structure are collected; Step 6: Calculate the theoretical air pressure value under the real-time temperature acquisition conditions, and compare the theoretical air pressure value with the real-time acquired actual air pressure value to calculate the corresponding air pressure deviation value; Step 7: When the air pressure deviation value continues to exceed the preset threshold within the preset time window, it is determined that the inflatable membrane structure has an air pressure abnormality caused by gas leakage, and a warning message is output.

2. The method for monitoring abnormal air pressure according to claim 1, characterized in that, Step 1 includes: establishing a finite element analysis model in ANSYS APDL modeling software based on the geometric dimensions, material mechanical parameters, initial air pressure parameters, and initial temperature parameters of the inflatable membrane structure.

3. The method for monitoring abnormal air pressure according to claim 1, characterized in that, Step 2 includes: the parameter correction includes correcting at least one equivalent parameter in the finite element analysis model, the equivalent parameter including at least one or more of the structural equivalent volume parameter, initial gas pressure parameter, and gas thermal parameter, and recalculating and analyzing the finite element analysis model based on the corrected equivalent parameter.

4. The method for monitoring abnormal air pressure according to claim 1, characterized in that, Step 3 includes: the range of temperature conditions is determined according to the actual use environment of the inflatable membrane structure, and the model is analyzed according to different temperature conditions from low to high to obtain a temperature-pressure correspondence dataset.

5. The method for monitoring abnormal air pressure according to claim 1, characterized in that, Step 4 includes: the theoretical pressure calculation module is an independent software function module or an embedded calculation module, which can be deployed in the structural health monitoring system or the host computer monitoring system; the theoretical pressure calculation module is established based on the reference data, and it adopts the method of table lookup calculation, interpolation calculation or fitting calculation. After inputting the current temperature value of the structure, it outputs the corresponding theoretical pressure prediction value.

6. The method for monitoring abnormal air pressure according to claim 1, characterized in that, Step 5 includes: synchronously collecting internal temperature and pressure data of the structure using temperature and pressure sensors installed inside the inflatable membrane structure at a preset sampling frequency.

7. The method for monitoring abnormal air pressure according to claim 1, characterized in that, Step 6 includes: the pressure deviation is the relative deviation between the actual monitored pressure value and the theoretical pressure prediction value at the corresponding temperature.

8. The method for monitoring abnormal air pressure according to claim 1, characterized in that, Step 7 includes: the length of the preset time window is set according to the pressure stability requirements of the inflatable membrane structure and the time resolution of the monitoring system; the preset threshold is a threshold determined according to the allowable pressure fluctuation range of the inflatable membrane structure; when the pressure deviation exceeds the preset threshold in a short period of time but does not continue to reach the preset time window, the pressure abnormality is judged as a transient abnormality caused by external transient disturbance, and a leakage warning is not triggered.

9. The method for monitoring abnormal air pressure according to claim 1, characterized in that: The parameter correction in step 2 and the temperature-pressure analysis in step 3 can be repeated periodically or as needed during the operation of the inflatable membrane structure, and the reference data can be updated to achieve continuous updating of the pressure prediction model.

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