Methods and systems for estimating and evaluating the ellipticity of the inner cylinder of cryogenic tank trucks

Abstract

This invention discloses a method and system for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker. The method involves obtaining the actual liquid level and design parameters of the tanker; calculating the theoretical liquid level using interpolation based on a liquid level-to-mass comparison table; calculating the maximum radial deviation of the elliptical deformed cylinder based on the theoretical, actual, and design parameters; calculating the ellipticity of the cylinder based on the maximum radial deviation and inner diameter; calculating the additional bending stress of the elliptical deformed cylinder under internal pressure conditions to determine if the ellipticity exceeds the limit; and calculating the critical instability pressure of the elliptical deformed cylinder under external pressure conditions using the formula for calculating the critical instability pressure of the elliptical deformed cylinder, comparing the critical instability pressure with the tanker's external pressure design value to determine if the ellipticity exceeds the limit. This method solves the problem of the inability to inspect the ellipticity of the inner cylinder of a tanker and proposes a criterion for evaluating the ellipticity limit, ensuring the safe operation of cryogenic tankers.

Description

Technical Field

[0001] This invention relates to the field of tank truck inspection and testing technology, and in particular to a method and system for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck. Background Technology

[0002] Cryogenic tank trucks are widely used for transporting liquefied gases in energy, chemical, and biopharmaceutical industries due to their large capacity, high mobility, and low cost. However, due to manufacturing errors and accidents during service, the tank truck body inevitably exhibits a certain degree of elliptical deformation. This elliptical deformation causes additional bending stress within the shell under internal pressure and reduces the structure's external pressure bearing capacity under external pressure, increasing the risk of structural damage or instability. Therefore, the ellipticity of the inner cylinder is a key focus of cryogenic tank truck inspection.

[0003] Ellipticity is defined as the ratio of the difference between the maximum and minimum diameters of the cylinder cross-section to the average diameter. Measuring the cylinder diameter typically requires entering the container to do so. To maintain the liquefied state of the medium, cryogenic tank trucks are mostly vacuum-insulated structures, with an inner cylinder encased in a vacuum-insulated outer cylinder. During routine inspections, it is impossible to enter the tank interior, making it impossible to inspect the ellipticity of the inner cylinder, which poses a safety hazard during the use of cryogenic tank trucks. Furthermore, there is currently a lack of clear assessment methods for the safety of elliptical deformed inner cylinders in tank trucks, resulting in a long-standing technical gap in the ellipticity testing of inner cylinders in in-service vacuum-insulated tank trucks. Inspectors can only refer to the cylinder ellipticity quality control indicators in the product manufacturing standards, but these indicators are not directly related to the safety of cryogenic tank trucks.

[0004] The currently used methods for detecting the ellipticity of the inner cylinder of cryogenic tank trucks have the following technical bottlenecks: 1. Limitations of inspection during the manufacturing stage: Traditional methods (such as coordinate measuring machines and laser trackers) require contact with the surface of the tanker body, which is only applicable to workpieces that can be freely accessed and cannot be applied to in-service cryogenic tankers.

[0005] 2. Inaccessibility during in-service testing: The physical isolation of the vacuum insulation layer completely seals the inner cylinder of the cryogenic tanker, making it impossible for any external probe or scanning equipment to penetrate the insulation layer for contact measurement.

[0006] 3. Data and assessment are disconnected: During testing, only geometric parameters are output, which need to be manually imported into the system for stress calculation. There is a lack of automated and standardized safety assessment process. Summary of the Invention

[0007] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method and system for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck. Utilizing the relationship between the liquid cross-sectional area of ​​an ideal cylindrical body and an elliptical deformed cylinder under the same filling volume, the maximum radial deviation of the elliptical deformed cylinder is calculated, thereby determining the ellipticity of the cylinder. This solves the problem of the inability to inspect the ellipticity of the inner cylinder of a cryogenic tank truck, and proposes a criterion for evaluating the ellipticity limit, ensuring the safe operation of cryogenic tank trucks.

[0008] On one hand, embodiments of the present invention provide a method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker, including: The actual liquid level height and tank truck design parameters are obtained. The tank truck design parameters include tank truck geometric parameters, tank truck material parameters, and tank truck design pressure. The tank truck geometric parameters include the inner diameter of the cylinder, the cylinder length, and the cylinder wall thickness. The tank truck material parameters include the material yield strength and the material elastic modulus. The tank truck design pressure includes the design external pressure and the design internal pressure. The theoretical liquid level height was calculated using interpolation based on the tanker truck liquid level and liquid mass comparison table. Based on the theoretical liquid level height, the actual liquid level height, and the tanker design parameters, and using the formula relating the liquid cross-sectional area of ​​an ideal cylindrical body and an elliptical deformed cylinder under the same liquid loading capacity, the maximum radial deviation of the elliptical deformed cylinder is calculated. The ellipticity of the cylinder is calculated based on the maximum radial deviation of the cylinder and the inner diameter of the cylinder. Based on the tanker design parameters and the maximum radial deviation of the cylinder, the additional bending stress of the elliptical deformed cylinder under internal pressure is calculated. The additional bending stress is compared with the allowable bending stress value to determine whether the ellipticity of the cylinder exceeds the limit. Based on the calculation formula for the critical instability pressure of the elliptical deformable cylinder, the critical instability pressure of the elliptical deformable cylinder under external pressure is calculated. The critical instability pressure is compared with the design value of the external pressure of the tank truck to determine whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified.

[0009] According to some embodiments of the present invention, the formula for calculating the liquid cross-sectional area of ​​an ideal cylindrical body is as follows: ; In the formula, S1 is the cross-sectional area of ​​the ideal cylindrical body containing liquid; H is the theoretical liquid level height; and R is the inner diameter of the cylinder. It is the central angle of the liquid surface.

[0010] According to some embodiments of the present invention, the formula for calculating the liquid cross-sectional area of ​​the elliptical deformable cylinder is as follows: ; ; , In the formula, S2 is the liquid cross-sectional area of ​​the elliptical deformed cylinder, and h is the actual liquid level height; It is the semi-major axis of the ellipse. It is the minor semi-axis of the ellipse. The eccentric angle of the ellipse, ( , () is the intersection of the liquid surface and the cylinder outline.

[0011] According to some embodiments of the present invention, the relationship between the liquid cross-sectional area of ​​an ideal cylindrical body and an elliptical deformed cylinder under the same liquid volume is expressed by the following formula: S1 = S2; In the formula, S1 is the liquid cross-sectional area of ​​the ideal cylindrical body, and S2 is the liquid cross-sectional area of ​​the elliptical deformed cylinder.

[0012] According to some embodiments of the present invention, the ellipticity of the cylinder is calculated based on the maximum radial deviation of the cylinder and the inner diameter of the cylinder, and the calculation formula is as follows: ; In the formula, 0% represents the ellipticity of the cylinder. R represents the maximum radial deviation of the cylinder, and R is the inner diameter of the cylinder.

[0013] According to some embodiments of the present invention, the additional bending stress of the elliptical deformed cylinder is calculated based on the tanker design parameters and the maximum radial deviation of the cylinder body. The calculation formula is as follows: In the formula, To account for the additional bending stress, P is the design internal pressure, R is the inner diameter of the cylinder, and t is the cylinder wall thickness. E represents the maximum radial deviation of the cylinder, and E is the elastic modulus of the material.

[0014] According to some embodiments of the present invention, the formula for calculating the critical instability pressure of the elliptical deformable cylinder is as follows: ; , ; , , , ; In the formula, The critical instability pressure, For instability parameters, n The wavenumber for cylinder instability. Ln The length of the cylinder. Poisson's ratio, This represents the maximum radial deviation of the cylinder. The equivalent radius of the cylinder is... , , , To calculate the equivalent radius of the cylinder Intermediate parameters.

[0015] According to some embodiments of the present invention, before the steps of determining whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified, the method further includes: System adaptive calibration is performed based on temperature compensation and pressure correction; Dynamically correct the effect of thermal expansion and contraction of the inner cylinder on the test results.

[0016] According to some embodiments of the present invention, after the steps of determining whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified, the method further includes: Store detection data and operating condition data to predict historical trends; Predict ellipticity degradation rate and remaining safe lifetime through time series analysis.

[0017] In another aspect, embodiments of the present invention provide a system for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck, used to implement the aforementioned method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck. The system includes: The sensor unit includes a level gauge, a temperature sensor, and a pressure sensor, which are used to acquire the actual liquid level, temperature, and pressure inside the tanker. Edge computing units are used to estimate the ellipticity of the tanker's inner cylinder and for system adaptive calibration; The cloud service platform is used to store detection data and operating condition data, and to make historical trend predictions.

[0018] The method and system for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck according to embodiments of the present invention have at least the following beneficial effects: Under the constraint of not being able to enter the interior of the tank during routine inspections of cryogenic tank trucks, a mathematical model of the deformable cylinder-volume relationship and an iterative algorithm are established to accurately quantify the ellipticity of the inner cylinder of the cryogenic tank truck without opening the tank or disrupting the vacuum. This deeply integrates geometric parameter detection with structural mechanics assessment, forming a coherent intelligent process of "data acquisition - model inversion - strength / stability assessment - conclusion output," which can directly output quantitative safety conclusions and clear safety status determinations for operation and maintenance decisions. This constructs an automated closed loop for cryogenic tank truck inspection and safety assessment, improving inspection efficiency and decision-making quality. Unique model self-validation, multi-condition analysis, and adaptive calibration functions ensure high accuracy and reliability of test results. This shortens the safety decision-making cycle from days to hours and reduces the risk of human error. Abandoning the direct measurement approach relying on physical contact or scanning, a creative indirect detection paradigm based on the inversion of geometric deformation according to the liquid level-volume relationship is proposed, achieving a fundamental breakthrough and realizing an automated and standardized safety assessment process.

[0019] In another aspect, embodiments of the present invention provide a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor runs the computer program, the processor executes the above-described method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker.

[0020] On the other hand, an embodiment of the present invention provides a storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-described method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of the method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the liquid level before and after elliptic deformation of the inner cylinder of a cryogenic tanker, illustrating the method for estimating and evaluating the ellipticity of the inner cylinder in this embodiment of the invention. Figure 3 This is a schematic diagram of two liquid levels for a cylindrical body and an elliptical deformed cylinder, representing the method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the centrifugal angle of the liquid surface in the elliptical deformed cylinder of the cryogenic tank truck, as described in the embodiment of the present invention, for estimating and evaluating the ellipticity of the inner cylinder. Figure 5 This is a schematic diagram of the central angle of the liquid surface in the cylinder of the cryogenic tank truck, which is an embodiment of the present invention for estimating and evaluating the ellipticity of the inner cylinder. Figure 6 This is a schematic diagram of an elliptical deformed cylinder in the method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker according to an embodiment of the present invention. Figure 7 This is a schematic diagram of the liquid level difference between the elliptic tanker cylinder and the cylindrical body with different liquid contents under different diameters, as shown in the embodiment of the present invention for estimating and evaluating the ellipticity of the inner cylinder of the cryogenic tanker. Figure 8 This is a functional block diagram of the cryogenic tank truck inner cylinder ellipticity estimation and evaluation system according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0024] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0025] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the stated number, and "above," "below," "within," etc. are understood to include the stated number. If "first," "second," etc. are used in the description, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of the indicated technical features.

[0026] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] This embodiment provides a method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker. Please refer to [link to relevant documentation]. Figure 1 The method for estimating and evaluating the ellipticity of the inner cylinder of the cryogenic tanker mainly includes steps S101~S106: S101. Obtain the actual liquid level height of the tank truck and the tank truck design parameters. The tank truck design parameters include the tank truck geometric parameters, tank truck material parameters, and tank truck design pressure. The tank truck geometric parameters include the inner diameter of the cylinder, the cylinder length, and the cylinder wall thickness. The tank truck material parameters include the material yield strength and the material elastic modulus. The tank truck design pressure includes the design external pressure and the design internal pressure.

[0028] S102. Based on the tank truck liquid level and liquid mass comparison table, the theoretical liquid level height is calculated by interpolation.

[0029] S103. Based on the theoretical liquid level height, the actual liquid level height, and the tank truck design parameters, and using the formula relating the liquid cross-sectional area of ​​an ideal cylindrical body and an elliptical deformed cylinder under the same liquid loading capacity, the maximum radial deviation of the elliptical deformed cylinder is calculated.

[0030] S104. The ellipticity of the cylinder is calculated based on the maximum radial deviation of the cylinder and the inner diameter of the cylinder.

[0031] S105. Based on the tanker design parameters and the maximum radial deviation of the cylinder, calculate the additional bending stress of the elliptical deformed cylinder under internal pressure conditions, compare the additional bending stress with the allowable bending stress value, and determine whether the ellipticity of the cylinder exceeds the limit.

[0032] S106. Based on the formula for calculating the critical instability pressure of an elliptical deformable cylinder, calculate the critical instability pressure of the elliptical deformable cylinder under external pressure conditions. Compare the critical instability pressure with the design value of the external pressure of the tank truck to determine whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified.

[0033] In step S103, the formula for calculating the liquid cross-sectional area of ​​an ideal cylindrical body is: ; In the formula, S1 is the cross-sectional area of ​​the ideal cylindrical body containing liquid; H is the theoretical liquid level height; and R is the inner diameter of the cylinder. It is the central angle of the liquid surface.

[0034] In step S103, the formula for calculating the liquid cross-sectional area of ​​the elliptical deformed cylinder is: ; ; , In the formula, S2 is the liquid cross-sectional area of ​​the elliptical deformed cylinder, and h is the actual liquid level height; It is the semi-major axis of the ellipse. It is the minor semi-axis of the ellipse. The eccentric angle of the ellipse, ( , () is the intersection of the liquid surface and the cylinder outline.

[0035] It should be noted that the formulas for calculating the liquid cross-sectional area of ​​an ideal cylindrical body and an elliptical deformed cylinder are derived based on geometric relationships. Please refer to [link / reference needed]. Figures 2 to 6 .

[0036] In step S103, the formula for calculating the equal liquid cross-sectional areas of an ideal cylindrical body and an elliptical deformed cylinder under the same liquid volume is: S1 = S2; In the formula, S1 is the liquid cross-sectional area of ​​the ideal cylindrical body, and S2 is the liquid cross-sectional area of ​​the elliptical deformed cylinder.

[0037] The physical principle is that for the same liquid volume V, whether in an ideal cylindrical body or an elliptical deformed cylinder, the volume should be equal. Combining the cylinder length L, the theoretical liquid level H, and the actual liquid level h, we obtain the core equation: S ideal (H) * L = S real (ω, h) * L, thus obtaining S ideal (H) = S real (ω, h); Where S1(H) is the area of ​​the sector calculated using the formula for the area of ​​an ideal circle, and is a known quantity; S real (ω, h) is the sector area calculated using the elliptic area formula, with ω being the only unknown in the equation. Substituting the specific expression for S2(ω, h) yields a nonlinear equation regarding ω. Numerical methods (such as the bisection method and Newton's method) are used to quickly and stably solve this equation, obtaining the best estimate of the maximum radial deviation ω, which can then be converted to the ellipticity of 0%. This allows for the quantification of key geometric deformation parameters of the tanker's inner cylinder under invisible and inaccessible conditions, enabling the inversion of geometric deformation based on the liquid level-volume relationship.

[0038] In step S104, based on the maximum radial deviation of the cylinder... The ellipticity of the cylinder is calculated based on the inner diameter of the cylinder. The formula is as follows: ; In the formula, 0% represents the ellipticity of the cylinder. R represents the maximum radial deviation of the cylinder, and R is the inner diameter of the cylinder.

[0039] In step S105, based on the tank truck design parameters and the maximum radial deviation of the cylinder, the additional bending stress of the elliptical deformed cylinder is calculated using the following formula: In the formula, To account for the additional bending stress, P is the design internal pressure, R is the inner diameter of the cylinder, and t is the cylinder wall thickness. E represents the maximum radial deviation of the cylinder, and E is the elastic modulus of the material.

[0040] In step S106, the formula for calculating the critical buckling pressure of the elliptical deformed cylinder is: ; , ; , , , ; In the formula, The critical instability pressure, For instability parameters, n The wavenumber for cylinder instability. L n The length of the cylinder. Poisson's ratio, The equivalent radius of the cylinder is... , , , To calculate the equivalent radius of the cylinder The intermediate parameters. It should be noted that this calculation formula is derived from the API-579 "Compliance with Use Evaluation" standard.

[0041] In some embodiments of the present invention, before the steps in step S106 of determining whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified, the method further includes: System adaptive calibration is performed based on temperature compensation and pressure correction; Dynamically correct the effect of thermal expansion and contraction of the inner cylinder on the test results.

[0042] By dynamically eliminating or compensating for systematic errors caused by changes in ambient temperature and pressure through adaptive calibration, the final ellipticity obtained is ensured to purely reflect geometric deformation, rather than apparent deformation disturbed by physical conditions. Using synchronously acquired temperature and pressure data, key input parameters of the model (such as the inner diameter of the cylinder and the theoretical liquid level) are dynamically corrected and converted to a unified reference state (usually the design temperature and design pressure) before geometric inversion. The resulting maximum radial deviation ω of the cylinder represents the true geometric deformation, excluding thermo-mechanical coupling interference.

[0043] The corrected formula is: R eff = R0*[1+α*(T T0)] + ΔR(P); In the formula, Reff R0 is the effective working radius; R0 is the design radius; α is the linear expansion coefficient of the cylinder material, such as approximately 1.7 × 10⁻⁶ for stainless steel. 5 ℃, used to correct for thermal expansion and contraction; T is the average temperature of the medium inside the cylinder collected in real time; T0 is the reference temperature, set to 20℃; ΔR(P) is the radius elastic increment caused by internal pressure, used to correct for pressure effects, and is derived from the circumferential strain formula of a thin-walled cylinder under internal pressure: ΔR(P) ≈ (P * R0) 2 ) / (E * t), where P is the internal pressure, R0 is the design radius, E is the elastic modulus, and t is the wall thickness.

[0044] Because liquid density increases at low temperatures, the liquid level will decrease for the same mass. The system has a built-in database of temperature-density relationships for common cryogenic media. The density ρ(T) is retrieved from the current temperature T and compared with a reference density. The actual liquid level is then proportionally corrected to obtain the equivalent liquid level at the reference temperature. In some embodiments of the present invention, after the steps of determining whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified in step S106, the method further includes: Store detection data and operating condition data to predict historical trends; Predict ellipticity degradation rate and remaining safe lifetime through time series analysis.

[0045] An independent time-series database is established for each tanker truck, and the aforementioned detection data and operating condition data are stored in encrypted order according to time, forming a unique health record for that tanker truck.

[0046] A trend prediction model is used to fit and extrapolate the historical ellipticity data series. The model formula is as follows: O(t) = O0*e kt + C*sin(ωt + ) ; In the formula, O(t) is the predicted ellipticity at time t, which is the output target of the model; O0 is the initial ellipticity obtained by fitting, reflecting the initial state of the tanker truck when it is put into use; k is the degradation rate constant, k>0 indicates that the ellipticity increases exponentially with time (accelerated degradation), such as material fatigue or local defect propagation; k≈0 indicates stable degradation; the case of k<0 is extremely rare and may indicate data fluctuation or measurement error; this parameter directly determines the rate of equipment lifespan consumption; it is used to simulate the irreversible, long-term overall deterioration trend caused by material fatigue, corrosion, permanent deformation accumulation, etc.; C is the fluctuation amplitude, ω is the fluctuation angular frequency, This is the initial phase.

[0047] A nonlinear least squares fitting algorithm is used to fit a series of historical time points t.i and the corresponding measured ellipticity O(t) i Substitute these parameters into the model, and the system will automatically iterate to find a set of optimal model parameters (O0, k, C, ω, ...). ), making the model prediction value O(t) i The overall error between the measured value and the actual value is minimized. Discrete, periodic point-like detection data is transformed into continuous, time-dimensional linear or even surface-like health status evolution maps. Moving from post-inspection diagnosis to pre-inspection warning, it changes the traditional passive mode of discovering problems and then addressing them, proactively predicting defect development trends and providing early warnings before safety margins are exhausted. It optimizes maintenance strategies, providing data-driven decision support for developing more scientific and economical inspection cycles and maintenance plans. It assesses the degradation rate, quantifies the average annual growth rate of the inner cylinder ellipticity or the inflection point of accelerated deterioration, and evaluates the impact of transportation conditions and operating habits on equipment lifespan. Combined with a safety assessment model, it predicts the remaining safe service life of the equipment to reach regulatory or safety limits under the current degradation rate.

[0048] In some embodiments of the present invention, the generation of a comprehensive safety status inspection report for tank trucks may also be included. The comprehensive safety inspection conclusion report for tank trucks includes whether the ellipticity of the tank body exceeds the limit and whether the ability to resist external pressure instability is qualified.

[0049] Please see Figure 8 This embodiment also provides a system for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck, used to implement the above-mentioned method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck. The system includes: The sensor unit 100 includes a level gauge, a temperature sensor, and a pressure sensor, which are used to acquire the actual liquid level height, temperature, and pressure inside the tanker tank, respectively. Edge computing unit 200 is used to estimate the ellipticity of the inner cylinder of the tanker and for system adaptive calibration; The cloud service platform 300 is used to store detection data and operating condition data, and to perform historical trend prediction.

[0050] The system stores data on the ellipticity, maximum radial deviation, and operating conditions of the tank truck's inner cylinder from each inspection. Through time-series analysis, it predicts the ellipticity degradation rate and remaining safe life. This enables a shift from periodic preventative inspections to condition-based predictive maintenance, providing early warnings of defects, preventing catastrophic accidents, and extending the safe service life of cryogenic tank trucks.

[0051] Example 1 The estimation and evaluation object in this embodiment is a liquid argon cryogenic tanker.

[0052] 1. Obtain the tank truck design parameters, as shown in Table 1.

[0053] Table 1 Design parameters of liquid argon tank truck 2. Fill the cryogenic tanker with 21,000 kg of liquid argon. Refer to Table 2 for the comparison between vehicle liquid level and liquid mass. Determine the theoretical liquid level height H as 1515 mm using interpolation. Obtain the actual liquid level height h of the tanker as 1498 mm using the liquid level gauge.

[0054] Table 2. Comparison of Liquid Level and Liquid Mass in Liquid Argon Tank Trucks It should be noted that the actual liquid level should be measured under the tanker's operating pressure and after sufficient settling time; the recommended liquid level is 60% greater than the tank diameter. Please refer to [link / reference]. Figure 7 When the actual liquid level is greater than 60% of the cylinder diameter, the liquid level difference between a 2% elliptic tanker cylinder and an ideal cylindrical cylinder is greater than 10 mm for different diameters. Considering the measurement error of the level gauge helps improve the accuracy of ellipticity estimation.

[0055] 3. Using the condition that the cross-sectional area of ​​the liquid in a cylindrical body and an elliptical deformed body are equal under the same liquid volume, solve for the maximum radial deviation of the body. And calculate the ellipticity of the cylinder.

[0056] (1) Calculate the central angle of the liquid surface as follows: = = 93.8°; (2) Based on the fact that the theoretical liquid level height H is greater than the inner diameter R of the cylinder, the liquid cross-sectional area S1 of the ideal cylinder is calculated as follows: = = 2285837mm 2 ; In the formula, S1 is the cross-sectional area of ​​the ideal cylindrical body containing liquid; H is the theoretical liquid level height; and R is the inner diameter of the cylinder. It is the central angle of the liquid surface.

[0057] (3) Based on the fact that the actual liquid level height h is greater than the minor semi-axis b of the ellipse ， The formula for calculating the liquid cross-sectional area S2 of an elliptical deformable cylinder is: ; ; ; , In the formula, S2 is the liquid cross-sectional area of ​​the elliptical deformed cylinder, and h is the actual liquid level height; It is the semi-major axis of the ellipse. It is the minor semi-axis of the ellipse. The eccentric angle of the ellipse, ( , () is the intersection of the liquid surface and the cylinder outline.

[0058] (4) Let the liquid cross-sectional area S1 of the ideal cylindrical body be equal to the liquid cross-sectional area S2 of the elliptical deformed cylinder, as follows: = ; = .

[0059] (5) Set the initial radial deviation based on historical test data and engineering experience values. The initial value is 8.5 mm. Based on this, with increments of 0.1 mm, the cross-sectional area S2 of the liquid in the elliptical deformed cylinder is calculated using an iterative method and compared with the cross-sectional area S1 of the liquid in the cylindrical cylinder. The calculation results show that when the radial deviation is 10.2 mm, the relative deviation between the cross-sectional areas of the liquid in the elliptical deformed cylinder and the cylindrical cylinder is less than 0.01%, thus allowing the maximum radial deviation of the elliptical deformed cylinder to be determined. The value is 10.2 mm. For detailed calculation parameters, please refer to Table 3.

[0060] Table 3 Detailed parameter table of relevant calculation process (6) Based on the maximum radial deviation of the cylinder Calculate the ellipticity of the cylinder O %: ; In the formula, 0% represents the ellipticity of the cylinder. R represents the maximum radial deviation of the cylinder, and R is the inner diameter of the cylinder.

[0061] Calculate the ellipticity of the cylinder O The percentage is 2.3%.

[0062] 4. Based on the design parameters, material parameters, and maximum radial deviation of the elliptical deformed cylinder of the tanker truck. Calculate the additional bending stress of the elliptical deformed cylinder under internal pressure conditions.

[0063] Based on the tanker truck design parameters, the design internal pressure P = 0.3 MPa, the material elasticity E = 195 GPa (i.e., 195000 MPa), and the wall thickness t = 3.5 mm; calculate the additional bending stress under the internal pressure of the elliptical deformed cylinder. as follows: 17.0 MPa; The calculated bending stress under compression inside the elliptical deformed cylinder was obtained. It is 17.0 MPa.

[0064] Allowable bending stress The value is taken as the material yield strength. One-third, calculated as follows: = = 310 / 3 103.3 MPa; Comparison of additional bending stress With allowable bending stress To determine if the ellipticity of the cylinder exceeds the limit, comparison shows that the bending stress under compression within the elliptical deformed cylinder... Less than the allowable value of bending stress This indicates that the ellipticity of the cylinder is within the limit, and the elliptical deformed cylinder can be used safely under internal pressure conditions.

[0065] 5. Calculate the critical buckling pressure of the elliptical deformable cylinder under external pressure conditions. The formula for calculating the critical buckling pressure of the elliptical deformable cylinder is as follows: ; , ; , , , ; In the formula, For instability parameters, n The wave number for cylinder instability is calculated starting from n=2 with increments of 0.1 until the minimum critical instability pressure is obtained. L n The length of the cylinder; This is Poisson's ratio, with a value of 0.3; The equivalent radius of the cylinder is... , , , To calculate the equivalent radius of the cylinder Intermediate parameters.

[0066] Compare the design external pressure with the critical instability pressure to determine if the ellipticity of the cylinder exceeds the limit. Based on the tank truck design parameters, the design external pressure p = 0.1 MPa, material elasticity E = 195 GPa, wall thickness t = 3.5 mm, and cylinder length L... n The maximum radial deviation of the cylinder is 2.265m. The thickness is 10.2 mm. Calculations show that the critical buckling pressure is minimum when n=7.5, and the critical buckling pressure under external pressure is 0.106 MPa. The critical buckling pressure of the elliptical deformable cylinder is greater than the design external pressure, indicating that the elliptical deformable cylinder can be safely used under external pressure conditions.

[0067] Example 2 The estimation and evaluation object in this embodiment is a cryogenic liquid oxygen tanker. 1. Obtain the tank truck design parameters, as shown in Table 4.

[0068] Table 4 Design parameters for liquid oxygen tank trucks 2. Fill the cryogenic tanker with 5000kg of liquid oxygen. Refer to Table 5, the liquid oxygen tanker liquid level and liquid mass comparison table, and determine the theoretical liquid level height H as 807mm by interpolation. The liquid level gauge shows that the actual liquid level h of the tanker is 797mm.

[0069] Table 5. Comparison of Liquid Oxygen Tank Truck Liquid Level and Liquid Mass 3. Using the condition that the liquid cross-sectional area of ​​a cylindrical body and an elliptical deformed cylinder are equal under the same liquid volume, solve for the maximum radial deviation of the cylinder. And calculate the ellipticity of the cylinder. O %.

[0070] (1) The central angle of the liquid surface was calculated according to the steps of Example 1. The angle is 168.1°, and the ideal cylindrical liquid cross-sectional area S1 is 1105243 mm². 2 .

[0071] (2) Let the cross-sectional area of ​​the liquid in the cylindrical body be equal to the cross-sectional area of ​​the elliptical cylinder, and solve for the maximum radial deviation of the elliptical deformed cylinder relative to the cylindrical body. Based on historical testing data and engineering experience, the initial radial deviation is set as follows: The initial value is 10 mm. Based on this, with increments of 0.1 mm, the cross-sectional area S2 of the liquid in the elliptical deformed cylinder is calculated using an iterative method and compared with the cross-sectional area S1 of the liquid in the cylindrical cylinder. The calculation results show that when the radial deviation is 11.3 mm, the relative deviation between the cross-sectional areas of the liquid in the elliptical deformed cylinder and the cylindrical cylinder is less than 0.01%. Therefore, the maximum radial deviation of the elliptical deformed cylinder can be obtained. The value is 11.3 mm. Detailed parameters for the relevant calculation process are shown in Table 6.

[0072] Table 6. Parameters for solving the maximum radial deviation of the cylinder (3) Based on the maximum radial deviation of the cylinder Calculate the ellipticity of the cylinder O %: ; Calculate the ellipticity of the cylinder O The percentage is 2.5%.

[0073] 4. Based on the tank truck design parameters and the maximum radial deviation of the cylinder, calculate the additional bending stress of the elliptical deformed cylinder under internal pressure conditions. Compare the bending stress with the allowable bending stress value to determine whether the ellipticity of the cylinder exceeds the limit.

[0074] Based on the tanker truck design parameters, the design internal pressure P = 0.52 MPa, the material elastic modulus E = 195 GPa (i.e., 195000 MPa), and the cylinder wall thickness t = 4 mm; calculate the additional bending stress under the internal pressure of the elliptical deformed cylinder. as follows: 21.5 MPa; The additional bending stress under internal pressure in the elliptical deformed cylinder was calculated. It is 21.5 MPa.

[0075] Allowable bending stress The value is taken as the material yield strength. One-third, calculated as follows: = = 230 / 3 76.7 MPa.

[0076] Comparison of additional bending stress With allowable bending stress To determine if the ellipticity of the cylinder exceeds the limit, the additional bending stress under internal compression of the elliptical deformed cylinder is compared. Less than the allowable value of bending stress This indicates that the ellipticity of the cylinder is within the limit, and the elliptical deformed cylinder can be used safely under internal pressure conditions.

[0077] 5. Calculate the critical buckling pressure of the elliptical deformed cylinder under external pressure conditions, compare the design pressure with the critical buckling pressure, and determine whether the ellipticity of the cylinder exceeds the limit.

[0078] The formula for calculating the critical buckling pressure of an elliptical deformable cylinder is as follows: ; , ; , , , ; In the formula, For instability parameters, n The wavenumber for cylinder instability. L n The length of the cylinder. Poisson's ratio, The equivalent radius of the cylinder is... , , , To calculate the equivalent radius of the cylinder Intermediate parameters.

[0079] Based on the tanker truck design parameters, the design external pressure p = 0.1 MPa, material elasticity E = 195 GPa, wall thickness t = 4 mm, and cylinder length L... n The diameter is 1.25m. Calculations show that the critical buckling pressure is minimum when n=9.6, and is 0.32MPa under external pressure conditions. The critical buckling pressure of the elliptical deformable cylinder is greater than the design external pressure, indicating that the elliptical deformable cylinder can be used safely under external pressure.

[0080] Addressing the constraint of inaccessible internal inspection of in-service tank trucks, this project abandons direct measurement methods relying on physical contact or scanning. Instead, it creatively proposes an indirect inspection paradigm based on the inversion of geometric deformation according to the liquid level-volume relationship, achieving a fundamental breakthrough. By establishing a mathematical model of the deformable cylinder-volume and an iterative algorithm, it achieves precise quantification of the ellipticity of the tank truck's internal cylinder without opening the tank or disrupting the vacuum. Deeply integrating geometric parameter detection with structural mechanics assessment, it forms a coherent intelligent workflow of "data acquisition - model inversion - strength / stability assessment - conclusion output," directly outputting quantitative safety conclusions and clear safety status determinations for operational decisions. This enables non-invasive ellipticity detection of the internal cylinder of vacuum-insulated tank trucks, improving inspection efficiency by over 80%. This shortens the safety decision-making cycle from days to hours and reduces the risk of human error. An automated closed loop for inspection and safety assessment is constructed, improving inspection efficiency and decision-making quality. Unique model self-validation, multi-condition analysis, and adaptive calibration functions ensure high accuracy and reliability of the inspection results. By fully utilizing existing sensors and routine operational data from tank trucks, inspection costs are reduced without the need for expensive specialized testing equipment or lengthy downtime for opening the tanks. This provides a standardized solution for predictive maintenance of tank trucks, driving the transformation of special equipment regulation from periodic inspections to condition monitoring.

[0081] Please see Figure 9 This application also provides a computer device 600, which includes a memory 601 and a processor 602. The processor 602 is used to run computer program instructions stored in the memory 601 to implement a method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck. The memory 601 includes at least one type of storage medium, including flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), magnetic memory, magnetic disk, optical disk, etc. In some embodiments, the memory 601 can be an internal storage unit of a computer device, such as a hard disk. In other embodiments, the memory 601 can be an external storage device of a computer device, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, Flash Card, etc. The memory 601 can also include both internal and external storage units of a computer device. The memory 601 can be used not only to store application software and various types of data installed on the computer device, but also to temporarily store data that has been output or will be output. Computer device 600 also includes bus 603. Bus 603 can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, it is represented by only one thick line in the figure, but this does not mean that there is only one bus or one type of bus. Computer device 600 may also include a display component 604. The display component 604 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen, etc. The display component 604 may also be appropriately referred to as a display device or display unit, used to display information processed in computer device 600 and to display a visual user interface.

[0082] Computer device 600 may also include communication component 605. Communication component 605 may optionally include wired communication component and / or wireless communication component (such as Wi-Fi communication component, Bluetooth communication component, etc.), and is typically used to establish communication connections between computer device 600 and other computer devices.

[0083] The figure only shows a computer device 600 with some components. Those skilled in the art will understand that the structure shown in the figure does not constitute a limitation on the computer device 600, and may include fewer or more components than shown, or combine certain components, or have different component arrangements.

[0084] This application also provides a storage medium that, when executed by a computer processor, enables the computer to perform the method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck provided in the above embodiments. For example, the storage medium can be ROM, RAM, CD-ROM, magnetic tape, floppy disk, USB flash drive, or optical data storage device, etc. It is worth noting that the storage medium mentioned in this application embodiment can be a non-volatile storage medium or a non-transient storage medium. It should be understood that all or part of the steps of the above embodiments can be implemented by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part as a computer program product. A computer program product includes one or more computer instructions; the computer instructions can be stored in the aforementioned storage medium. That is, in some embodiments, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute the method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck provided in the above embodiments. The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck, characterized in that, include: The actual liquid level height and tank truck design parameters are obtained. The tank truck design parameters include tank truck geometric parameters, tank truck material parameters, and tank truck design pressure. The tank truck geometric parameters include the inner diameter of the cylinder, the cylinder length, and the cylinder wall thickness. The tank truck material parameters include the material yield strength and the material elastic modulus. The tank truck design pressure includes the design external pressure and the design internal pressure. The theoretical liquid level height was calculated using interpolation based on the tanker truck liquid level and liquid mass comparison table. Based on the theoretical liquid level height, the actual liquid level height, and the tanker design parameters, and using the formula relating the liquid cross-sectional area of ​​an ideal cylindrical body and an elliptical deformed cylinder under the same liquid loading capacity, the maximum radial deviation of the elliptical deformed cylinder is calculated. The ellipticity of the cylinder is calculated based on the maximum radial deviation of the cylinder and the inner diameter of the cylinder. Based on the tanker design parameters and the maximum radial deviation of the cylinder, the additional bending stress of the elliptical deformed cylinder under internal pressure is calculated. The additional bending stress is compared with the allowable bending stress value to determine whether the ellipticity of the cylinder exceeds the limit. Based on the calculation formula for the critical instability pressure of the elliptical deformable cylinder, the critical instability pressure of the elliptical deformable cylinder under external pressure is calculated. The critical instability pressure is compared with the design value of the external pressure of the tank truck to determine whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified.

2. The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker according to claim 1, characterized in that, The formula for calculating the cross-sectional area of ​​a liquid in an ideal cylindrical body is: ； In the formula, S1 is the cross-sectional area of ​​the ideal cylindrical body containing liquid, H is the theoretical liquid level height, and R is the inner diameter of the cylinder. It is the central angle of the liquid surface.

3. The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker according to claim 2, characterized in that, The formula for calculating the liquid cross-sectional area of ​​an elliptical deformable cylinder is: ； ； ， In the formula, S2 is the liquid cross-sectional area of ​​the elliptical deformed cylinder, and h is the actual liquid level height; It is the semi-major axis of the ellipse. It is the minor semi-axis of the ellipse. The eccentric angle of the ellipse, ( , () represents the intersection of the liquid surface and the cylinder profile, and R represents the inner diameter of the cylinder. This represents the maximum radial deviation of the cylinder.

4. The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker truck according to claim 3, characterized in that, The formula relating the cross-sectional areas of the liquid in an ideal cylindrical body and an elliptical deformed cylinder for the same liquid volume is: S1 = S2; In the formula, S1 is the liquid cross-sectional area of ​​the ideal cylindrical body, and S2 is the liquid cross-sectional area of ​​the elliptical deformed cylinder.

5. The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker truck according to claim 4, characterized in that, The ellipticity of the cylinder is calculated based on the maximum radial deviation of the cylinder and the inner diameter of the cylinder. The calculation formula is as follows: ； In the formula, 0% represents the ellipticity of the cylinder. R represents the maximum radial deviation of the cylinder, and R is the inner diameter of the cylinder.

6. The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker truck according to claim 1, characterized in that, Based on the tanker design parameters and the maximum radial deviation of the cylinder, the additional bending stress of the elliptical deformed cylinder is calculated using the following formula: In the formula, To account for the additional bending stress, P is the design internal pressure, R is the inner diameter of the cylinder, and t is the cylinder wall thickness. E represents the maximum radial deviation of the cylinder, and E is the elastic modulus of the material.

7. The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker truck according to claim 6, characterized in that, The formula for calculating the critical buckling pressure of an elliptical deformable cylinder is: ； ， ； ， ， ， ； In the formula, The critical instability pressure, For instability parameters, n The wavenumber for cylinder instability. L n The length of the cylinder. Poisson's ratio, This represents the maximum radial deviation of the cylinder. The equivalent radius of the cylinder is... , , , To calculate the equivalent radius of the cylinder Intermediate parameters.

8. The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker according to claim 1, characterized in that, Before the steps of determining whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified, the method further includes: System adaptive calibration is performed based on temperature compensation and pressure correction; Dynamically correct the effect of thermal expansion and contraction of the inner cylinder on the test results.

9. The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker according to claim 1, characterized in that, After the steps of determining whether the ellipticity of the cylinder exceeds the limit and whether the resistance to external pressure instability is qualified, the method further includes: Store detection data and operating condition data to predict historical trends; Predict ellipticity degradation rate and remaining safe lifetime through time series analysis.

10. A system for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tank truck, characterized in that, The method for estimating and evaluating the ellipticity of the inner cylinder of a cryogenic tanker as described in any one of claims 1 to 9 includes: The sensor unit includes a level gauge, a temperature sensor, and a pressure sensor, which are used to acquire the actual liquid level, temperature, and pressure inside the tanker. Edge computing units are used to estimate the ellipticity of the tanker's inner cylinder and for system adaptive calibration; The cloud service platform is used to store detection data and operating condition data, and to make historical trend predictions.

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