Method and system for checking longitudinal bending of ship based on component classification and data linkage

Abstract

The first aspect of the present application discloses a ship longitudinal bending strength checking method based on component classification and data linkage. The second aspect of the present application discloses a ship longitudinal bending strength checking system for implementing the above ship longitudinal bending strength checking method. The core of the present application is to build an efficient and accurate checking system by scientific component classification and close data linkage, and to deeply couple the professional ship strength checking logic and the data processing capability of the general electronic spreadsheet. The system is based on a unique component numbering system divided according to the plate rack position, combined with the pre-existing double classification of components, to realize the fine management of the ship longitudinal bending strength checking process. At the same time, the system developed based on the Excel platform solidifies the complex checking process into an orderly associated calculation table, ensuring the automatic transmission and efficient processing of data.

Description

Technical Field

[0001] This invention relates to a method and system for calculating the longitudinal bending stress of hull beams in the overall longitudinal strength verification of ships, belonging to the field of ship structural design technology. Background Technology

[0002] Longitudinal bending verification is a crucial step in the overall longitudinal strength verification process during ship structural design. For classed vessels, such as bulk carriers, oil tankers, and container ships, commercial software from classification societies is typically used; while for non-classed vessels, such as certain types of government vessels and other workboats, traditional verification methods are usually employed.

[0003] Existing traditional verification methods suffer from a severe disconnect between initial component data management and subsequent multi-step verification calculations. First, at the data source level, existing methods employ an isolated and rigid numbering and statistical system for the vast number of cross-sectional components. They fail to standardize the classification and identification based on the instability mechanical characteristics and stress roles of different components. This results in the initial established cross-sectional component characteristics failing to provide categorized input data for subsequent critical steps such as critical stress calculation, stability verification, and longitudinal bending verification. Second, at the execution level of the verification process, this lack of pre-classified data directly severs the connection between each verification step.

[0004] Because the characteristics of cross-sectional components do not allow for rapid screening based on classification and labeling, technicians are forced to return to the original, chaotic list and rely on manual experience and visual identification to search, filter, and record whenever a specific type of component is needed at each step. This process is not only tedious and inefficient but also greatly increases the risk of human error. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies, such as cumbersome operation, low efficiency and easy error, caused by the disconnect between the characteristics of cross-sectional components and subsequent calculation processes, and to provide a standardized, streamlined and automated method and system based on component classification and data linkage.

[0006] To achieve the above objectives, the first aspect of this invention discloses a method for verifying the longitudinal bending strength of ships based on component classification and data linkage, characterized by comprising the following steps: S1: Select the verification section and verification working condition, and determine the ship section bending moment; S2: Based on the mid-section view, establish a section component numbering and statistical system according to the location of deck plate frame, bottom plate frame, side plate frame, etc.; and in this system, classify the components into three categories according to the instability type and two categories according to the stress type based on their mechanical behavior. S3: Calculate the section moment of inertia and neutral axis position of the verification section; S4: Based on the aforementioned instability type classification, calculate the critical stress of each type of component using the corresponding standard formula; S5: Calculate the local bending stress of the components in the bottom plate frame; S6: Under the combined action of the overall longitudinal section bending moment and the local bottom plate frame load, check the stability of the section members; if there are unstable members, return to step S2 to modify the design scheme and recalculate until there are no unstable members. S7: Under the combined action of the overall longitudinal section bending moment and the local bottom plate frame load, check the overall longitudinal bending stress of the section members according to the allowable stress criterion; if there are members that do not meet the criterion, return to step S2 to modify the design scheme and recalculate until all members meet the criterion.

[0007] Preferably, in step S2, the instability type classification includes: instability type 1 - plate; instability type 2 - T-profile panel; instability type 3 - longitudinal rib.

[0008] Preferably, in step S2, the stress type classification includes: stress type 1 - all cross-sectional members bearing total longitudinal bending stress; stress type 2 - bottom plate structure members bearing additional local bending stress.

[0009] Preferably, in step S5, the calculation of the local bending stress is performed using the displacement method for a simplified three-dimensional cross beam system of the bottom plate frame, and the two characteristic positions of mid-span and end are distinguished.

[0010] The second aspect of this invention discloses a ship longitudinal bending strength verification system for implementing the above-mentioned ship longitudinal bending strength verification method, characterized in that the ship longitudinal bending strength verification system is built on an Excel spreadsheet platform and includes: A steel profile database worksheet is used to store data such as the cross-sectional area, moment of inertia, and center of gravity height of commonly used bulb flats or user-defined profiles; A verification calculation worksheet contains seven sequentially linked calculation tables, each corresponding to one of the seven steps of the verification method, including: Table 1: Sectional Bending Moment Table, used for inputting and storing data from step S1; Table 2: Profile Component Characteristics Table, used to implement the component numbering, statistics and classification in step S2; Table 3: Sectional Moment of Inertia and Neutral Axis Position Table, used to show the calculation results of step S3; Tables 4-1, 4-2, and 4-3: Critical stress calculation tables corresponding to the three types of instability, used to perform step S4; Table 5: Bending stress table of bottom plate frame, used for performing step S5; Table 6: Stability Check Table for Sectional Components, used to perform step S6; Table 7: Check Table for Overall Longitudinal Bending Stress of Sectional Members, used to perform step S7.

[0011] Preferably, the steel profile database and the verification calculation worksheet are linked through data verification or lookup reference functions; when the user selects the steel profile specifications used for the component, the system automatically retrieves the corresponding cross-sectional area and moment of inertia data from the steel profile database and uses them for the calculation of the longitudinal bone critical stress in Table 4-3.

[0012] Preferably, Table 2 has a function to quickly filter data on components according to instability type and stress type.

[0013] Preferably, Table 6 is equipped with an automatic judgment unit based on calculation results; the automatic judgment unit outputs a clear indication of "yes" or "no" for whether the component is unstable through built-in conditional formatting, wherein "yes" is indicated by a dark background and "no" is indicated by no dark background; Table 7 is equipped with an automatic judgment unit based on calculation results; the automatic judgment unit outputs a clear indication of "satisfied" or "not satisfied" for whether the bending stress of the component meets the allowable value through built-in conditional formatting, wherein "satisfied" is indicated by no dark background and "not satisfied" is indicated by a dark background.

[0014] Preferably, steps S6 and S7 form an iterative closed loop; when the automatic judgment unit outputs "no" or "failed" indication, the user can optimize the design scheme by modifying the size or specifications of the corresponding component in Table 2, and the data in all subsequent tables will be automatically updated accordingly, so the user can re-verify without manually modifying the subsequent tables.

[0015] Preferably, the tables in the verification calculation worksheet are linked automatically through Excel's formula linking and data referencing functions, so that subsequent tables can automatically obtain the calculation results of the aforementioned tables as input.

[0016] The core of this invention, a method and system for verifying the longitudinal bending strength of ships based on component classification and data linkage, lies in constructing an efficient and accurate verification system through scientific component classification and close data linkage. This deeply couples professional ship strength verification logic with the data processing capabilities of general-purpose spreadsheets. Based on a unique component numbering system categorized by platen position, combined with pre-defined dual component classification, this system achieves refined management of the ship's longitudinal bending strength verification process. Simultaneously, the system, developed using the Excel platform, solidifies the complex verification process into an ordered, interconnected calculation table, ensuring automatic data transfer and efficient processing.

[0017] Compared with existing technical solutions, the present invention has the following beneficial effects: 1. Forward-looking data management: By classifying components in advance according to both instability and stress type, data management can directly and accurately serve subsequent calculation needs, fundamentally eliminating the confusion and errors of manual screening.

[0018] 2. Automated verification process: The Excel-based integrated system enables seamless data linking and automatic transfer between each step, avoiding repetitive input, significantly improving efficiency, and reducing human error rate.

[0019] 3. Clear operation route: The clearly defined seven steps and closed-loop iterative process provide technical personnel with a clear verification roadmap, lower the operation threshold, and ensure the repeatability and reliability of the results. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the bending moment in the cross section of Table 1; Figure 2 This is a schematic diagram of the characteristics of the cross-section components in Table 2; Figure 3 This is a schematic diagram of the moment of inertia and neutral axis of the cross section in Table 3; Figure 4 The diagrams for calculating critical stresses in Tables 4-1 to 4-3 are shown below. Figure 5 Table 5 shows a schematic diagram of local bending stress. Figure 6 This is a schematic diagram of the stability check of the cross-sectional components shown in Table 6. Figure 7 This is a schematic diagram of the longitudinal bending stress check of the cross-section member in Table 7; Figure 8 This is a schematic diagram illustrating the implementation process of the present invention and the linkage between Excel table data. Detailed Implementation

[0021] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0022] This invention discloses a method for verifying the longitudinal bending strength of ships based on component classification and data linkage, comprising the following steps: S1. The midship section of a 3000-ton workboat is used as the verification section, as this section bears the most critical stress during longitudinal bending. The verification conditions are midship camber and midship sagging. The bending moment of the section consists of the still water bending moment and the wave bending moment. The still water bending moment can be directly obtained from the loading manual, with the still water bending moments of midship camber and midship sagging being 56000 kN*m and -35000 kN*m, respectively. The wave bending moment can be directly calculated using ship wave load software, with the wave bending moments of midship camber and midship sagging being 53000 kN*m and -40000 kN*m, respectively. These values ​​are then entered into the cells with dark backgrounds in Table 1, and the combined bending moments of midship camber and midship sagging are automatically summed.

[0023] Table 1 shows the cross-sectional bending moments, corresponding to step S1 above. It is used to record cross-sectional bending moment data, including the specific values ​​of still water bending moment and wave bending moment, and automatically calculates the composite bending moment.

[0024] S2. Based on the mid-section view of the design scheme, a comprehensive and detailed section component numbering and statistical system is established, divided according to different locations such as deck frame, bottom frame, and side frame. This data system pre-classifies components according to both instability type and stress type. For example... Figure 1 As shown, instability types are categorized as follows: Instability Type 1 - Plates, such as Deck 1 plate (6mm thick) numbered 1 and Flat keel (10mm thick) numbered 11; Instability Type 2 - T-section panels, such as Deck 1 longitudinal girder panel (12mm thick) numbered 6; Instability Type 3 - Longitudinal ribs, such as Deck 1 longitudinal rib (steel designation P10, corresponding to the steel database) numbered 2 and bottom side girder longitudinal rib (steel designation P14a, corresponding to the steel database) numbered 10. Instability types are also categorized as follows: Stress Type 1 - All cross-sectional members bearing total longitudinal bending stress, such as Deck 1 side plate numbered 4; Stress Type 2 - Bottom plate structure members bearing additional local bending stress. These members, in addition to bearing total longitudinal bending stress, also experience additional local bending stress due to localized forces on the bottom plate structure, such as bottom longitudinal rib numbered 12 (steel designation P14a, corresponding to the steel database). Other component characteristic values ​​are obtained from the design drawings and directly entered into the cells with dark backgrounds in Table 2.

[0025] Table 2 shows the characteristics of the cross-sectional components, corresponding to step S2 above. This table not only records the basic information of each cross-sectional component in detail, but also adds columns indicating the instability type and stress type of the cross-sectional components to clearly identify the classification of each component. It also has a filtering function, facilitating the filtering and analysis of component data according to different needs in subsequent steps. For example, it can quickly filter out components with specific instability or stress types. This classification serves as a "navigation map" for all subsequent automated calculations.

[0026] S3. Use external structural analysis software, such as BV's Mars2000, to obtain the section moment of inertia and neutral axis height values ​​and fill them into the cells with dark backgrounds in Table 3, such as... Figure 3 As shown.

[0027] Table 3 shows the section moment of inertia and neutral axis position, corresponding to step S3 above. It is used to store and process the section moment of inertia and neutral axis position data obtained from the external structural analysis software. These data are important bases for subsequent calculations.

[0028] S4. Based on different instability types, the corresponding standard formulas are used to calculate the critical stress of the cross-sectional member. For instability type 1—plate, the formula for calculating the critical stress is:

[0029] in It is the material's yield strength, Euler stress. Calculate using the following formula:

[0030] For the 2-T profile panel with instability type, the formula for calculating its critical stress is:

[0031] Its Euler stress Calculate using the following formula:

[0032] In the formula The width is half the width of the panel.

[0033] For the instability type 3-longitudinal bone, its critical stress The calculation formula is:

[0034] Its Euler stress Calculate using the following formula:

[0035] In the formula It is the elastic modulus of the material, taken as... MPa; Moment of inertia of longitudinal bone with plate cm 4 ; longitudinal section area of ​​plate cm 2 ; The thickness of the strip is in mm. It is the distance between longitudinal bones in mm. It is the cross-sectional area of ​​the longitudinal bone in cm².2 ;coefficient ; Position of longitudinal bone with plate mm; Stability of the strip width mm; The strong frame spacing is in centimeters; The above calculation formulas are embedded in Tables 4-1 to 4-3. Simply select the component numbers corresponding to different instability types from Table 2 and copy them to the component number columns with dark backgrounds in Tables 4-1 to 4-3. The other cells will automatically retrieve the component information corresponding to that component number from Table 2 or the profile database using the VLOOKUP function, and automatically calculate the critical stress of different types of instable components. Figure 4 As shown, the instability type columns in Tables 4-1 to 4-3 are used to check whether the entered component number is a valid component number.

[0036] Tables 4-1 to 4-3 all correspond to step S4 above, automatically dividing the components for calculation according to different instability types. Table 4-1 is for instability type 1, corresponding to the critical stress calculation of the plate; Table 4-2 is for instability type 2, corresponding to the critical stress calculation of the T-profile panel; Table 4-3 is for instability type 3, corresponding to the critical stress calculation of the longitudinal rib. Operation method: Simply filter out the component numbers corresponding to different instability types from Table 2 and copy them to the component number columns in Tables 4-1 to 4-3. Subsequent cells will automatically retrieve the corresponding component information from Table 2 or Sheet1 using the VLOOKUP function (e.g., for Table 4-1, this includes project name, instability type, longitudinal stiffener spacing, plate thickness, Euler stress, and yield strength; for Table 4-2, it includes project name, instability type, panel half-width, plate thickness, Euler stress, and yield strength; for Table 4-3, it includes project name, instability type, steel section code, cross-sectional area, moment of inertia, centroidal axis distance, strip plate thickness, strong frame spacing, longitudinal stiffener spacing, and yield strength). The remaining table information will be automatically calculated using the corresponding standard formulas for intermediate processes and final critical stress. The instability type columns in Tables 4-1 to 4-3 are used to check whether the entered component number is a valid component number.

[0037] S5. Abstract the bottom slab frame into a three-dimensional intersecting beam system model, considering the bending stiffness, shear stiffness, and connection conditions between beams. Based on the displacement method principle in structural mechanics, establish equilibrium equations with nodal displacements as the basic unknowns. Solve these equations to obtain the nodal displacement values. Calculate the bending stress at the mid-span and end positions of the members based on the nodal displacements and the mechanical properties of the beams. This method fully considers the actual stress conditions and structural characteristics of the bottom slab frame, enabling relatively accurate calculation of the local bending stress of the members. For Table 5, firstly, select the member numbers corresponding to stress type 2 from Table 2, add the suffixes ".1" and ".2" (representing the end and mid-span respectively), and fill them into the member number column with a dark background in Table 5. Then, fill the local bending stress calculated by the displacement method into the central arch column with a dark background. He Zhongchui Two columns, such as Figure 5 As shown in Table 5, the instability type column is used to check whether the entered component number is a valid component number.

[0038] Table 5 shows the bending stress calculation for stress type 2, specifically for the bottom plate frame, corresponding to step S5 above. It stores the local bending stress of the bottom plate frame components, recording the calculated bending stress data at the mid-span and ends. Operation method: Simply filter the component number corresponding to stress type 2 from Table 2, add the suffixes ".1" and ".2" (representing the end and mid-span respectively), and fill them into the component number column of Table 5. The instability type column in Table 5 is used to check whether the entered component number is a valid component number.

[0039] S6. Under the combined action of the overall longitudinal section bending moment and the local bottom plate frame load, the stability of the section members is checked. For Table 6, simply copy the member numbers corresponding to stress type 1 from Table 2 and stress type 2 from Table 5 to the member number column in Table 6. The remaining cells are automatically searched and calculated using the VLOOKUP function from Tables 4-1 to 4-3 or Table 2. For the stability check, the automatically calculated compressive stress of the member is compared with the critical stress. If the corresponding cells for member number 1 and member number 4 clearly indicate "yes" and have a dark background (e.g., ...), the stability is checked. Figure 6 If the current design fails to meet stability requirements, the following changes are made: The plate thickness of component 1 in Table 2 is changed from 6mm to 7mm; the plate thickness of component 4 is changed from 7mm to 8mm; the plate thicknesses of components 2 and 3 are changed to 7mm and 8mm respectively; the longitudinal stiffener spacing of the entire deck frame is changed from 800mm to 400mm; and other parts remain unchanged. Tables 2-6 can automatically recheck the stability of the cross-sectional components. After the modification, all components show "meets" stability requirements, and the next step is to check the total longitudinal bending stress.

[0040] Table 6 shows the stability check of the cross-sectional components. Corresponding to step S6 above, based on the data calculated earlier, the stability of the cross-sectional components is checked according to the stability criterion, and the check results are automatically recorded in the table. This allows for a direct assessment of which components are at risk of instability and forms a closed-loop feedback mechanism. Operation method: Simply copy the component numbers corresponding to stress type 1 from Table 2 and the component numbers corresponding to stress type 2 from Table 5 to the component number column in Table 6.

[0041] S7. Under the combined action of the overall longitudinal bending moment and the local bottom plate load, the overall longitudinal bending stress of the section member is finally checked. For Table 7, no manual input of information is required; the necessary information is seamlessly integrated and automatically receives the data from the previous steps. For the overall longitudinal bending stress check, the calculated overall longitudinal bending stress of the member is compared with the stress criterion. For stress type 1, the overall bending stress criterion is 0.38. The stress is taken as 89.3 MPa; for stress type 2, the total bending stress criterion is 0.46. The value is 108.1 MPa. It was found that the corresponding cells for component numbers 13.2 and 14.2 explicitly indicate "not satisfied" and are highlighted with a dark background (e.g., ...). Figure 7 If the current design fails to meet the bending strength requirements, the plate thickness of component 13 in Table 2 is modified from 9mm to 10mm, and the plate thickness of components 14 and 15 is correspondingly modified to 10mm, while other parts remain unchanged. Tables 2 to 7 automatically recheck the bending strength of the cross-sectional components. After modifying the design, all components show "meets" the bending strength requirements, the verification process is complete, indicating that the longitudinal bending stress of the ship meets the criterion requirements, and the current design is the final design.

[0042] Table 7 shows the total longitudinal bending stress check of the cross-sectional components. Corresponding to step S7 above, the total longitudinal bending stress of the cross-sectional components is checked according to the allowable stress criterion. The check results are automatically recorded to determine whether any components do not meet the stress requirements, and a closed-loop feedback is formed. Operation method: No manual information filling is required; the required information is seamlessly connected and automatically receives the data stream from the previous steps.

Claims

1. A method for verifying the longitudinal bending strength of ships based on component classification and data linkage, characterized in that, Includes the following steps: S1: Select the verification section and verification working condition, and determine the ship section bending moment; S2: Based on the mid-section view, establish a component numbering and statistical system according to the locations of deck frame, bottom frame, and side frame; within this system, pre-classify the components into three categories based on instability type and two categories based on stress type according to their mechanical behavior; S3: Calculate the section moment of inertia and neutral axis position of the check section; S4: Based on the instability type classification, calculate the critical stress of each type of component using the corresponding standard formula; S5: Calculate the local bending stress of the components in the bottom frame; S6: Under the combined action of the overall longitudinal section bending moment and the local bottom plate frame load, check the stability of the section members; if there are unstable members, return to step S2 to modify the design scheme and recalculate until there are no unstable members. S7: Under the combined action of the overall longitudinal section bending moment and the local bottom plate frame load, check the overall longitudinal bending stress of the section members according to the allowable stress criterion; if there are members that do not meet the criterion, return to step S2 to modify the design scheme and recalculate until all members meet the criterion.

2. The method for verifying the longitudinal bending strength of a ship according to claim 1, characterized in that, In step S2, the instability type classification includes: instability type 1 - plate; instability type 2 - T-profile panel; instability type 3 - longitudinal rib.

3. The method for verifying the longitudinal bending strength of a ship according to claim 1, characterized in that, In step S2, the stress type classification includes: stress type 1 - all cross-sectional components that bear total longitudinal bending stress; stress type 2 - bottom plate structure components that additionally bear local bending stress.

4. The method for verifying the longitudinal bending strength of a ship according to claim 1, characterized in that, In step S5, the calculation of the local bending stress is performed on a simplified three-dimensional cross beam system of the bottom plate frame using the displacement method, and the two characteristic positions of mid-span and end are distinguished.

5. A ship longitudinal bending strength verification system that implements the ship longitudinal bending strength verification method as described in any one of claims 1-4, characterized in that, The ship longitudinal bending strength verification system is built on an Excel spreadsheet platform and includes: a steel profile database worksheet, which stores data such as the cross-sectional area, moment of inertia and center of gravity height of commonly used bulb flat steel or user-defined profiles; A verification calculation worksheet contains seven sequentially linked calculation tables, each corresponding to one of the seven steps of the verification method: Table 1: Sectional Bending Moment Table, used to input and store data for step S1; Table 2: Sectional Component Characteristics Table, used to implement component numbering, statistics, and classification for step S2; Table 3: Sectional Moment of Inertia and Neutral Axis Position Table, used to display the calculation results for step S3; Tables 4-1, 4-2, and 4-3: Critical Stress Calculation Tables corresponding to three types of instability, used to execute step S4; Table 5: Bottom Plate Bending Stress Table, used to execute step S5; Table 6: Sectional Component Stability Verification Table, used to execute step S6; Table 7: Sectional Component Overall Longitudinal Bending Stress Verification Table, used to execute step S7.

6. The ship longitudinal bending strength verification system according to claim 5, characterized in that, The steel profile database and the verification calculation worksheet are linked through data verification or lookup reference functions; when the user selects the steel profile specifications used for the component, the system automatically retrieves the corresponding cross-sectional area and moment of inertia data from the steel profile database and uses them for the calculation of the longitudinal bone critical stress in Table 4-3.

7. The ship longitudinal bending strength verification system according to claim 5, characterized in that, Table 2 provides a function for quickly filtering components based on instability type and stress type.

8. The ship longitudinal bending strength verification system according to claim 5, characterized in that, Table 6 includes an automatic judgment unit based on calculation results. This automatic judgment unit uses built-in conditional formatting to output a clear "yes" or "no" indication of whether a component is unstable. "Yes" is indicated by a dark background, and "no" by no dark background. Table 7 also includes an automatic judgment unit based on calculation results. This automatic judgment unit uses built-in conditional formatting to output a clear "satisfied" or "unsatisfied" indication of whether the bending stress of a component meets the allowable value. "Satisfied" is indicated by no dark background, and "unsatisfied" by a dark background.

9. The ship longitudinal bending strength verification system according to claim 5, characterized in that, Steps S6 and S7 form an iterative closed loop; when the automatic judgment unit outputs "no" or "failed" indication, the user can optimize the design scheme by modifying the size or specifications of the corresponding component in Table 2, and all data in the subsequent tables will be automatically updated accordingly, so the user can re-verify without manually modifying the subsequent tables.

10. The ship longitudinal bending strength verification system according to claim 5, characterized in that, The tables in the verification calculation worksheet are linked automatically through Excel's formula linking and data referencing functions, allowing subsequent tables to automatically obtain the calculation results from the aforementioned tables as input.

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