Ship hull corrosion limit strength evaluation method based on corrosion real-time monitoring data

Abstract

The present application belongs to the field of hull ultimate strength evaluation, and particularly relates to a hull corrosion ultimate strength evaluation method based on corrosion real-time monitoring data, comprising the following steps: S1, collecting thickness data of a hull component plate; S2, calculating the section characteristics of the hull component plate before and after corrosion; S3, calculating the ultimate bending moment and material yield stress of the hull component plate; and S4, real-time ultimate strength evaluation of the hull component plate under corrosion; the present application realizes real-time dynamic monitoring and evaluation of the ultimate strength of the hull structure under the influence of corrosion, and provides scientific and reliable data support through accurate section reduction and step-by-step approximation calculation, so as to help develop more effective maintenance and repair strategies and ensure the safety and reliability of the hull structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of hull ultimate strength evaluation, and particularly relates to a hull corrosion ultimate strength evaluation method based on real-time corrosion monitoring data. BACKGROUND

[0002] In the marine environment, the hull structure is long-term exposed to seawater and is prone to corrosion. Corrosion can cause the thickness of the hull structure to thin, thereby seriously affecting the structural strength and safety of the hull. The corrosion problem not only threatens the normal navigation of the ship, but also may cause a major safety accident. Therefore, real-time monitoring of the corrosion condition of the hull and dynamic evaluation of the ultimate strength of its structure are crucial to ensure the safety of ship navigation.

[0003] Traditional hull corrosion monitoring methods mainly rely on periodic manual inspection and maintenance. These methods require a large amount of cost and time, and are prone to problems such as data lag, incompleteness, and insufficient accuracy. These defects make it difficult for traditional methods to achieve real-time monitoring of the corrosion condition of the hull, and also make it difficult to dynamically evaluate the impact of corrosion on the structural strength of the hull, thereby restricting the efficiency and scientificity of ship safety management.

[0004] Existing corrosion monitoring methods based on sensing technology and data analysis can collect hull plate thickness and corrosion-related data in real time through sensors, and combine data processing and analysis technology to monitor the corrosion condition of the hull in real time. However, these methods still have deficiencies in systematicness and efficiency, and are usually difficult to combine corrosion data with hull ultimate strength evaluation, and also difficult to accurately provide scientific maintenance and repair strategies, thereby limiting their actual application effect.

[0005] Based on the above problems, there is an urgent need for a technical method that can realize real-time corrosion data monitoring and dynamic evaluation of the ultimate strength of the hull structure, in order to improve the safety and reliability of the hull structure, and provide data support for scientific maintenance and repair decisions. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a hull corrosion ultimate strength evaluation method based on real-time corrosion monitoring data, which dynamically checks and updates the ultimate strength evaluation model to ensure that the strength evaluation of the hull under corrosion conditions is more accurate and reliable.

[0007] The present application provides a hull corrosion ultimate strength evaluation method based on real-time corrosion monitoring data, comprising the following steps:

[0008] S1, collecting thickness data of the hull component plate:

[0009] using an ultrasonic thickness gauge to measure the thickness of the hull component plate in real time;

[0010] S2, calculating the section properties of the hull member plate before and after corrosion:

[0011] According to the thickness data of the hull member plate before corrosion measured in step S1, the section area, static moment and section moment of inertia of the initial state of the hull member plate are calculated;

[0012] According to the thickness data of the hull member plate after corrosion measured in step S1, the real-time section area, static moment and section moment of inertia of the hull member plate after corrosion are calculated;

[0013] S3, calculating the ultimate bending moment and material yield stress of the hull member plate:

[0014] According to the compression or tension of the hull member plate, the ultimate bending moment M u of the hull member plate is calculated;

[0015] S4, real-time ultimate strength evaluation of the hull member plate after corrosion;

[0016] Based on the real-time section properties after corrosion obtained in step S2, in the hogging or sagging working condition, the following conditions are met

[0017] ;

[0018] It is considered that the ultimate strength of the hull member plate under the section properties meets the requirements;

[0019] Wherein, M u is the ultimate bending moment obtained in step S3;

[0020] M s is the still water bending moment;

[0021] M w is the wave additional bending moment, which is calculated by the following formula

[0022]

[0023] Wherein, h represents the calculated wave height, L represents the designed waterline length at the normal displacement, D represents the waterline width at the ship's hump when the normal displacement is considered, U1 is the influence coefficient considering the speed and still water bending moment, U2 is the dynamic water pressure correction coefficient, and K b represents the coefficient considering the linear shadow;

[0024] M d is the slamming bending moment, which is calculated by the following formula

[0025]

[0026] In the formula, h represents the calculated wave height, the unit is m, K is a coefficient, which is obtained by the designed waterline length L at the normal displacement and the depth of the waist at the normal displacement T through The calculation results are B w is the waterline width at the ship waist at the normal displacement.

[0027] The technical scheme realizes that the limit strength of the ship body structure under the corrosion influence can be monitored and evaluated in real time and dynamically, and scientific and reliable data support can be provided through the precise section reduction and step-by-step approximation calculation mode, so as to help to make more effective maintenance and repair strategies, and to ensure the safety and reliability of the ship body structure.

[0028] In some embodiments, the section area A of the ship body component plate in the initial state is:

[0029] (1)

[0030] Wherein, is the area of the i-th small area divided by the initial section of the ship body component plate;

[0031] The static moment B of the ship body component plate in the initial state is:

[0032] (2)

[0033] Wherein, represents the distance between the center of gravity of the i-th small area divided by the initial section of the ship body component plate and the reference axis.

[0034] In some embodiments, the section inertia moment I of the ship body component plate in the initial state is:

[0035]

[0036] Wherein, C is the reference axis inertia moment of the ship body component plate in the initial state, which is calculated according to The calculation results are, is the area of the i-th small area divided by the initial section of the ship body component plate, represents the distance between the center of gravity of the i-th small area divided by the initial section of the ship body component plate and the reference axis, is an influence factor, which is a fixed value;

[0037] ɛ is the distance between the neutral axis of the ship body component plate and the reference axis, which is calculated according to The calculation results are B, the static moment of the ship body component plate in the initial state, which is calculated according to formula (2); A is the section area of the ship body component plate in the initial state, which is calculated according to formula (1).

[0038] In some embodiments, in step S2, before calculating the section properties of the ship hull member plate after corrosion, the area reduction coefficient of the ship hull member plate needs to be calculated ,

[0039]

[0040] wherein, is the Euler stress, calculated by , t is the thickness of the ship hull member plate, and b is the longitudinal spacing;

[0041] σ i is the working stress, calculated by , wherein, M is the bending moment of the ship hull member plate, calculated by , Ms is the hydrostatic bending moment of the ship hull member plate, M w is the wave additional bending moment of the ship hull member plate, calculated by the formula , wherein h is the calculated wave height, L is the designed waterline length at the normal displacement, D is the waterline width at the ship's hump at the normal displacement, U1 is the influence coefficient considering the speed and the hydrostatic bending moment, U2 is the dynamic water pressure correction coefficient, K b represents the coefficient considering the linear shape; M d is the slamming bending moment of the ship hull member plate, calculated by the formula , wherein K is a coefficient, calculated by , L is the designed waterline length at the normal displacement, and T is the depth of the midship section at the normal displacement.

[0042] In some embodiments, in step S2, the section area A' of the ship hull member plate in real time after corrosion is:

[0043]

[0044] wherein A is the section area of the ship hull member plate in the initial state, is the area of the i-th small area divided by the initial section of the ship hull member plate, is the area reduction coefficient of the ship hull member plate;

[0045] The static moment of the ship hull member plate after corrosion is B':

[0046]

[0047] wherein B is the static moment of the ship hull member plate in the initial state, is the area of the i-th small area divided by the initial section of the ship hull member plate, is the area reduction coefficient of the ship hull member plate, a distance between a center of gravity of an i-th small area divided by an initial section of the hull member plate and the reference axis;

[0048] In some embodiments, a section inertia moment of the hull member plate after corrosion is I':

[0049]

[0050] wherein C' is a reference axis inertia moment of the hull member plate after corrosion, C is a reference axis inertia moment of the hull member plate in an initial state, an area of an i-th small area divided by an initial section of the hull member plate, a distance between a center of gravity of an i-th small area divided by an initial section of the hull member plate and the reference axis;

[0051] ɛ' is a distance between a neutral axis of the hull member plate after corrosion and the reference axis, according to B' is a static moment of the hull member plate after corrosion, and A' is a section area of the hull member plate after corrosion.

[0052] In some embodiments, in step S3, when the deck is compressed, a limit bending moment M u is a product of a buckling critical stress of the deck and a section modulus of the deck, but is not greater than a product of a section modulus of the bottom plate frame and a material yield stress of the bottom plate frame;

[0053] When the deck is stretched, a limit bending moment M u is a product of a material yield stress of the deck and a section modulus of the deck, but is not greater than a product of a section modulus of the bottom plate frame and a buckling critical stress of the bottom plate frame;

[0054] wherein the buckling critical stress of the deck, the material yield stress of the bottom plate frame, the material yield stress of the deck, and the buckling critical stress of the bottom plate frame are known quantities;

[0055] The section modulus of the deck and the section modulus of the bottom plate frame can be calculated by a formula

[0056]

[0057] wherein, I' is a section inertia moment of the hull member plate after corrosion, and W denotes a section modulus after a corrosion area of the deck or the bottom frame plate is reduced, I' is a section inertia moment of the hull member plate after corrosion, l is a vertical distance between the neutral axis and a farthest point of the section of the hull member plate.

[0058] In some embodiments, the mechanical properties of the complex ship body structure are equivalent to an equivalent beam model of the whole, and the limit bending moment M of the ship body component plate in step S3 is calculated u When the equivalent beam section modulus of the deck and the bottom plate frame is used, the step-by-step approximation calculation is obtained, if the difference between the total longitudinal normal stress in the last approximation and the previous approximation is not more than 0.05, the data of the last time is used as the final calculation value, if the final calculation value is less than 0.8 times the equivalent beam section coefficient obtained by the first approximation calculation, measures are taken to improve the stability of the main component of the equivalent beam.

[0059] 1. Based on the above technical solutions, the present application realizes real-time dynamic monitoring and evaluation of the limit strength of the ship body structure under the influence of corrosion, and provides scientific and reliable data support through accurate section reduction and step-by-step approximation calculation, helps to develop more effective maintenance and repair strategies, and ensures the safety and reliability of the ship body structure. BRIEF DESCRIPTION OF DRAWINGS

[0060] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0061] Figure 1 The flowchart of the embodiments of the present application. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is described and explained below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and do not limit the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0063] Obviously, the drawings described below are only some examples or embodiments of the present application, and for those of ordinary skill in the art, the present application can be applied to other similar scenarios without creative labor. In addition, it can be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacture or production changes based on the technical content disclosed in the present application are only routine technical means, and should not be understood as insufficient disclosure of the present application.

[0064] Reference to“an embodiment” or“the embodiment” in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in one embodiment” or“in at least one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is expressly understood that any of the embodiments described in this application can be combined with any of the other embodiments that are described in the application without matching features being repeated.

[0065] The embodiment takes the ship's midship section of a certain in-service wharf ship as an example to monitor the corrosion of the in-service wharf ship in real time, and carries out corrosion limit strength evaluation research work based on the service environment, i.e. the corrosion state of the ship body under the conditions of different corrosion years of 10 years, 15 years, 20 years and 25 years. Specifically, the steps include:

[0066] S1, collecting the thickness data of the ship body component plate:

[0067] The thickness of the ship body component plate is measured in real time using an ultrasonic thickness gauge, and the thickness data of the ship body component plate before and after corrosion is recorded;

[0068] S2, calculating the section characteristics of the ship body component plate before and after corrosion:

[0069] According to the thickness data of the ship body component plate before corrosion measured in step S1, the section area, static moment and section moment of inertia of the initial state of the ship body component plate are calculated. Specifically:

[0070] The section area A of the initial state of the ship body component plate is:

[0071] (1)

[0072] Wherein, is the area of the i-th small area divided by the initial section of the ship body component plate;

[0073] The static moment B of the initial state of the ship body component plate is:

[0074] (2)

[0075] Wherein, represents the distance from the center of gravity of the i-th small area divided by the initial section of the ship body component plate to the reference axis;

[0076] The section moment of inertia I of the initial state of the ship body component plate is:

[0077]

[0078] Wherein, C is the reference axis moment of inertia of the initial state of the ship body component plate, which is calculated according to calculated, the area of the i-th small region divided by the initial section of the hull member plate, the distance between the center of gravity of the i-th small region divided by the initial section of the hull member plate and the reference axis, is a fixed value;

[0079] is the distance between the neutral axis of the hull member plate and the reference axis, and is calculated according to calculated, B is the static moment B of the hull member plate in the initial state, which is calculated according to formula (2); A is the section area of the hull member plate in the initial state, which is calculated according to formula (1);

[0080] According to the thickness data of the hull member plate after corrosion measured in step S1, the area reduction coefficient of the hull member plate after corrosion needs to be calculated before calculating the section characteristics of the hull member plate after corrosion ,

[0081]

[0082] wherein, is the Euler stress, which is calculated according to , t is the thickness of the hull member plate, and b is the longitudinal spacing;

[0083] is the working stress, which is calculated according to , wherein, M is the bending moment of the hull member plate, which is calculated according to , Ms is the hydrostatic bending moment of the hull member plate, and the hydrostatic bending moment Ms is positive in the hogging,

[0084] M w is the wave additional bending moment of the hull member plate, which is calculated according to formula

[0085]

[0086] calculated, wherein h is the calculated wave height, L is the designed waterline length at the normal displacement, D is the waterline width at the ship's bulge at the normal displacement, U1 is the influence coefficient considering the speed and the hydrostatic bending moment, U2 is the dynamic water pressure correction coefficient, K b represents the coefficient considering the linear shape; M d is the slamming bending moment of the hull member plate, which is calculated according to formula , wherein K is a coefficient, which is calculated according to , L is the designed waterline length at the normal displacement, and T is the depth of the midship section at the normal displacement;

[0087] The section area, the static moment and the section moment of inertia of the hull member plate after corrosion are calculated, specifically:

[0088] The cross-sectional area A' of the ship member plate after corrosion is:

[0089]

[0090] A is the cross-sectional area of the ship member plate in the initial state, is the area of the i-th small region divided by the initial cross-section of the ship member plate, is the area reduction coefficient of the ship member plate;

[0091] The static moment B' of the ship member plate after corrosion is:

[0092]

[0093] B is the static moment of the ship member plate in the initial state, is the area of the i-th small region divided by the initial cross-section of the ship member plate, is the area reduction coefficient of the ship member plate, is the distance between the center of gravity of the i-th small region divided by the initial cross-section of the ship member plate and the reference axis;

[0094] The cross-sectional moment of inertia I' of the ship member plate after corrosion is:

[0095]

[0096] C' is the reference axis moment of inertia of the ship member plate after corrosion, C is the reference axis moment of inertia of the ship member plate in the initial state, is the area of the i-th small region divided by the initial cross-section of the ship member plate, is the distance between the center of gravity of the i-th small region divided by the initial cross-section of the ship member plate and the reference axis;

[0097] ɛ' is the distance between the neutral axis of the ship member plate after corrosion and the reference axis, according to B' is the static moment of the ship member plate after corrosion, and A' is the cross-sectional area of the ship member plate after corrosion;

[0098] S3, calculating the ultimate bending moment and material yield stress of the ship member plate:

[0099] According to the compression or tension of the ship member plate, the ultimate bending moment M u of the ship member plate is calculated.

[0100] When the deck is compressed, the ultimate bending moment M uIt is the product of the critical buckling stress of the deck and the section modulus of the deck, but not greater than the product of the section modulus of the bottom plate frame and the yield stress of the bottom plate frame material;

[0101] When the deck is under tension, the ultimate bending moment M of the hull plate is... u It is the product of the material yield stress of the deck and the section modulus of the deck, but not greater than the product of the section modulus of the bottom plate frame and the buckling critical stress of the bottom plate frame.

[0102] Among them, the buckling critical stress of the deck, the material yield stress of the bottom plate frame, the material yield stress of the deck, and the buckling critical stress of the bottom plate frame are all known data;

[0103] The section modulus of the deck and the section modulus of the bottom plate frame can both be determined by formulas.

[0104]

[0105] The calculation shows that, W I' represents the section modulus after the reduction of the corrosion area of ​​the deck or bottom frame plate, and I' is the section moment of inertia of the hull component plate after corrosion calculated in step S2. l The distance from the neutral axis is the perpendicular distance to the farthest point of the cross-section of the corresponding hull component plate.

[0106] Based on the calculated section modulus of the deck and the section modulus of the bottom plate frame, the ultimate bending moment M of the hull component plate can be calculated. u ;

[0107] In calculating the ultimate bending moment M of the hull component plate u In this implementation, the equivalent beam method is adopted. Due to the complexity of the hull plate structure, including plates, frames, and other components, it is difficult to solve directly during analysis. To simplify the analysis, the mechanical properties of these complex components are equivalent to a whole "equivalent beam" model. The equivalent beam, by comprehensively considering the cross-sectional properties of longitudinal members, transverse members, and plates, can more accurately reflect the overall strength and stiffness characteristics of the hull under bending moment. When performing the cross-sectional reduction analysis of the hull plate structure under corrosion, in the first approximate calculation of the equivalent beam elements, that is, in step S2, when calculating the cross-sectional properties before corrosion causes area reduction, the cross-sectional area of ​​the longitudinal members is fully included. However, in the second and subsequent calculations of the equivalent beam elements, plates with a width of 0.25 times the longitudinal skeleton spacing on both sides are not reduced.

[0108] In calculating the ultimate bending moment M uThe equivalent beam section modulus is calculated by step-by-step approximation, if the difference between the total longitudinal normal stress in the last approximation and that in the previous approximation is less than 0.05, the data in the last approximation is taken as the final calculation value; if the final calculation value is less than 0.8 times the equivalent beam section modulus calculated in the first approximation, measures are taken to improve the stability of the main components of the equivalent beam.

[0109] S4, real-time limit strength evaluation of the corroded hull component plate;

[0110] Based on the real-time section characteristics after corrosion obtained in step S2, in the hogging or sagging working condition, the following conditions are met

[0111] ;

[0112] It is considered that the limit strength of the hull component plate under the section characteristics meets the requirements;

[0113] Wherein, M u is the limit bending moment obtained in step S3;

[0114] M s is the still water bending moment;

[0115] M w is the wave additional bending moment, which is calculated by the following formula

[0116]

[0117] Wherein, h represents the calculation wave height, unit m, L represents the design waterline length at the normal displacement, D represents the waterline width at the ship's bulge at the normal displacement, U1 is the influence coefficient considering the speed and the still water bending moment, U2 is the dynamic water pressure correction coefficient, K b represents the coefficient considering the linear shape;

[0118] M d is the slamming bending moment, which is calculated by the following formula

[0119]

[0120] Wherein, h represents the calculation wave height, unit m, K is a coefficient, which is calculated by the design waterline length L at the normal displacement and the depth of the amidship at the normal displacement T through , B W is the waterline width at the ship's amidship at the normal displacement.

[0121] Through the arrangement of the actual monitoring data, according to the section area, static moment, moment of inertia and other numerical values under the corrosion influence of different time periods, 10 years, 15 years, 20 years and 25 years, the limit strength of the hull structure is dynamically calculated and checked. The working conditions in the checking include the hogging and sagging working conditions. The limit strength checking results are shown in Tables 1 to 4:

[0122] Table 10 Checking results of section elements and ultimate strength under 10-year limit condition

[0123]

[0124] Table 2 Checking results of section elements and ultimate strength under 15-year limit condition

[0125]

[0126] Table 3 Checking results of section elements and ultimate strength under 20-year limit condition

[0127]

[0128] Table 4 Checking results of section elements and ultimate strength under 25-year limit condition

[0129]

[0130] The above results show that the ratio of the ultimate bending moment of the ship's midship section in the two states of hogging and sagging to the sum of the static water bending moment, the wave additional bending moment and the slamming bending moment is greater than 1.5, that is, the ultimate strength of the ship within 25 years of service meets the specification requirements.

[0131] The technical solution realizes real-time dynamic monitoring and evaluation of the ultimate strength of the ship structure under the influence of corrosion, and provides scientific and reliable data support through precise section reduction and step-by-step approximation calculation, helps to develop more effective maintenance and repair strategies, and ensures the safety and reliability of the ship structure.

[0132] Finally, it should be noted that: the embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to.

[0133] The above embodiments are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones without departing from the spirit of the present application. They should all be included in the technical solution range of the present application.

Claims

1. A method for assessing the corrosion limit strength of ship hulls based on real-time corrosion monitoring data, characterized in that, Includes the following steps: S1. Collect thickness data of hull component plates: The thickness of the ship's hull components was measured in real time using an ultrasonic thickness gauge. S2. Calculate the cross-sectional characteristics of the hull component plates before and after corrosion: Based on the thickness data of the hull component plate before corrosion obtained in step S1, calculate the cross-sectional area, static moment, and cross-sectional moment of inertia of the hull component plate in its initial state. Based on the thickness data of the corroded hull component plate obtained in step S1, calculate the real-time cross-sectional area, static moment, and cross-sectional moment of inertia of the corroded hull component plate. S3. Calculate the ultimate bending moment and material yield stress of the hull components: Calculate the ultimate bending moment M of the hull component plate based on whether it is subjected to compression or tension. u ; S4. Real-time ultimate strength assessment of hull component plates under corrosion: Based on the real-time profile characteristics obtained in step S2 after corrosion, under the conditions of mid-arch or mid-sag, the following conditions are met: ； This means that the ultimate strength of the hull component plate under the characteristics of this section is considered to meet the requirements. Among them, M u The ultimate bending moment obtained in step S3; M s For static bending moment; M w The additional bending moment applied to the wave is calculated using the following formula. In the formula, h represents the calculated wave height, L represents the design waterline length at normal displacement, D represents the waterline width at the helix at normal displacement, U1 is the coefficient taking into account the influence of speed and still water moment, U2 is the correction coefficient for hydrodynamic pressure, and K... b The coefficient representing the linear shadow; M d The slamming moment is calculated using the following formula. In the formula, h represents the calculated wave height, and K is a coefficient derived from the design waterline length L at normal discharge and the midship draft T at normal discharge. Calculations show that B w The width of the waterline at midships when the ship is at normal displacement; In step S3, when the deck is compressed, the ultimate bending moment M of the hull component plate... u It is the product of the critical buckling stress of the deck and the section modulus of the deck, but not greater than the product of the section modulus of the bottom plate frame and the yield stress of the bottom plate frame material; When the deck is under tension, the ultimate bending moment M of the hull component plate u It is the product of the material yield stress of the deck and the section modulus of the deck, but not greater than the product of the section modulus of the bottom plate frame and the buckling critical stress of the bottom plate frame; Among them, the buckling critical stress of the deck, the yield stress of the bottom plate frame material, the yield stress of the deck material, and the buckling critical stress of the bottom plate frame are all known quantities; The section modulus of the deck and the section modulus of the bottom plate frame can both be determined by formulas. The calculation shows that, W I' represents the section modulus after the reduction of the corroded area of ​​the deck or bottom frame plate, and I' is the section moment of inertia of the corroded hull component plate. l The distance from the neutral axis is the perpendicular distance to the farthest point of the cross-section of the corresponding hull component plate.

2. The method for assessing the corrosion limit strength of ship hulls based on real-time corrosion monitoring data according to claim 1, characterized in that, In step S2, the cross-sectional area A of the hull component plate in its initial state is: （1） in, The area of ​​the i-th small region into which the initial cross-section of the hull component plate is divided; The static moment B of the hull component plate in its initial state is: （2） in, This represents the distance from the reference axis to the centroid of the i-th small region into which the initial section of the hull component plate is divided.

3. The method for assessing the corrosion limit strength of ship hulls based on real-time corrosion monitoring data according to claim 2, characterized in that, The initial section moment of inertia I of the hull component plate is: Where C is the reference moment of inertia of the hull component plate in its initial state, according to Calculated, Let be the area of ​​the i-th small region into which the initial cross-section of the hull component plate is divided. This represents the distance from the reference axis to the centroid of the i-th small region into which the initial section of the hull component plate is divided. The impact factor is a fixed value. ɛ is the distance from the reference axis to the neutral axis of the hull component plate, according to The calculated values ​​are as follows: B is the static moment of the hull component plate in its initial state, calculated by formula (2); A is the cross-sectional area of ​​the hull component plate in its initial state, calculated by formula (1).

4. The method for assessing the corrosion limit strength of ship hulls based on real-time corrosion monitoring data according to claim 3, characterized in that, In step S2, before calculating the cross-sectional characteristics of the hull component plate after corrosion, it is necessary to calculate the area reduction factor of the hull component plate. , in, For Euler stress, by We find that t is the thickness of the hull component plate and b is the longitudinal girder spacing; For working stress, by The calculation results show that, M The bending moment of the hull component plate is given by... Calculated, M S The hydrostatic bending moment M of the hull component plate is given by... w Add a bending moment M to the wave-induced bending moment on the hull component plate. d The slamming bending moment is the bending moment of the hull component plate.

5. The method for assessing the corrosion limit strength of ship hulls based on real-time corrosion monitoring data according to claim 4, characterized in that, In step S2, the real-time cross-sectional area A' of the corroded hull component plate is: Where A is the cross-sectional area of ​​the hull component plate in its initial state. Let be the area of ​​the i-th small region into which the initial cross-section of the hull component plate is divided. The area reduction factor is the area of ​​the hull component plate. The static moment of the corroded hull component plate is B': Wherein, B is the static moment of the hull component plate in its initial state. Let be the area of ​​the i-th small region into which the initial cross-section of the hull component plate is divided. Here is the area reduction factor for the hull component plate. This represents the distance from the reference axis to the centroid of the i-th small region into which the initial section of the hull component plate is divided.

6. The method for assessing the corrosion limit strength of ship hulls based on real-time corrosion monitoring data according to claim 5, characterized in that, The moment of inertia of the corroded hull component plate is I': Wherein, C' is the reference moment of inertia of the hull component plate after corrosion, and C is the reference moment of inertia of the hull component plate in its initial state. Let be the area of ​​the i-th small region into which the initial cross-section of the hull component plate is divided. This represents the distance from the reference axis to the centroid of the i-th small region into which the initial section of the hull component plate is divided; ɛ' is the distance from the reference axis to the neutral axis after the corrosion of the hull component plate, according to The calculated values ​​are as follows: B' is the static moment of the corroded hull component plate, and A' is the cross-sectional area of ​​the corroded hull component plate.

7. The method for assessing the ultimate corrosion strength of a ship's hull based on real-time corrosion monitoring data according to claim 6, characterized in that, The mechanical properties of the complex hull structure are equivalent to an overall equivalent beam model. In step S3, the ultimate bending moment M of the hull component plate is calculated. u When calculating the equivalent beam section modulus of the deck and the bottom plate frame, the values ​​are obtained by stepwise approximation. If the difference between the total longitudinal normal stress in the later approximation and the earlier approximation does not exceed 0.05, the data of the later approximation is used as the final calculated value. If the final calculated value is less than 0.8 times the equivalent beam section coefficient obtained by the first approximation, measures are taken to improve the stability of the main components of the equivalent beam.

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