Multi-target position bending moment and shearing force adjusting method for finite element calculation of ship body cabin section

Abstract

The invention discloses a multi-target position bending moment and shearing force adjusting method for finite element calculation of a ship body cabin section, which comprises the following steps of: performing finite element calculation on the ship body cabin section, selecting a plurality of target positions in a target cabin section, and respectively setting target values of vertical bending moment and shearing force corresponding to each target position; constructing a three-cabin-section model; selecting a target position; applying bending moments to the head end face and the tail end face of the three-cabin-section model respectively, so that the shearing force and the bending moments of the target position are adjusted towards the target value direction corresponding to the target position; comparing the matching degree between the adjusted bending moment distribution of the target position and a target value corresponding to the target position; checking the stress state of the component in the target position area; and for other target positions, respectively repeating the previous steps. According to the method, the accuracy and reliability of structural strength evaluation can be improved, the structural strength of the whole target cabin section is ensured to be comprehensively checked, and the actual engineering requirements are met.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and in particular to a method for adjusting the bending moment and shear force at multiple locations in finite element calculations of hull sections. Background Technology

[0002] In ship structural strength assessment, finite element analysis of hull sections is a crucial method for verifying the load-bearing capacity of hull beams. Its core principle is ensuring that the calculated vertical bending moment and shear force distribution closely match the target values ​​specified in the code. However, existing techniques for adjusting finite element analyses of ships not covered by harmonized common code (CCC) standards (such as container ships and ore carriers) have significant limitations. These ships are currently not included in the harmonized common code methods, especially in the fore and stern cargo hold areas, where suitable software and methods are lacking to adjust the bending moment and shear force at each strong frame location to the target values ​​according to the harmonized common code methods. Figure 1 As shown, for this type of ship, the traditional single-target position adjustment strategy is difficult to match the gradient change law of the target bending moment in the bow and stern cargo hold areas, resulting in local distortion of the calculation results and directly affecting the accuracy and reliability of the structural strength assessment.

[0003] For the fore and stern cargo holds, the target bending moment decreases non-linearly along the longitudinal direction of the hold section (e.g., ...). Figure 1 As shown in the diagram, if only the middle section is used as the adjustment reference, the deviation between the bending moment at the fore and stern and the target value can reach 20%-40%. This deviation directly leads to the following problems:

[0004] Distortion of bending moment in the fore and stern regions: The gradient change of the target bending moment at the fore and stern of the compartment is not accurately simulated, and the local stress calculation results deviate from the actual working conditions.

[0005] Existing methods typically only perform strength checks on the bending moment in the middle of the compartment. When calculating the bending moment in the cargo hold areas at the bow and stern using this method, there are cases where the bending moment deviates significantly from the allowable bending moment. The stress state of the structural details (especially the longitudinal members involved in the overall longitudinal strength) is not effectively verified, which may lead to potential structural safety hazards. Summary of the Invention

[0006] To overcome the aforementioned deficiencies in the existing technology, this invention provides a method for adjusting the bending moment and shear force at multiple locations in finite element calculations of ship hull sections.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] A method for adjusting the bending moment and shear force at multiple locations in finite element analysis of a ship hull section, comprising:

[0009] Step 1: Perform finite element analysis on the hull section, select multiple target locations in the target section, and set the target values ​​of vertical bending moment and shear force for each target location.

[0010] Step 2: Construct a three-section model, which includes the target section and two sections adjacent to the target section before and after it;

[0011] Step 3, select a target location;

[0012] Step 4: Apply bending moments to the bow and stern faces of the three-section model respectively, so that the shear force and bending moment at the target position are adjusted in the direction of the target value corresponding to the target position.

[0013] Step 5: Compare the adjusted bending moment distribution at the target location with the target value at the target location; check the stress state of the components in the target location area.

[0014] Step 6: Repeat steps 4 and 5 for each of the other target locations.

[0015] Furthermore, in step 1, at least three target locations are selected within the target compartment.

[0016] Furthermore, the target location includes the forward transverse bulkhead of the target section, or the middle of the target section, or the rear transverse bulkhead of the target section.

[0017] Furthermore, in step 1, the target values ​​of vertical bending moment and shear force corresponding to each target location are determined by ship design specifications or by calculation.

[0018] Furthermore, in step 2, the three-section model is used to simulate the actual load transfer path.

[0019] Furthermore, in step 2, the three-section model includes the longitudinal components of the hull beam, which include the deck, bottom plate, and side structure.

[0020] Furthermore, in step 4, the bending moment M caused by the local load is first obtained. local_loc_i Adjusting the bending moment M by shear force shear_i Adjust the shear force at the target location to the target value, and then apply M. target_loc_i -M local_loc_i- M shear_i Adjust the vertical bending moment to the target value M. target_loc_i .

[0021] Furthermore, in step 5, the stress state of the components in the target location area is checked to ensure that the stress state meets the allowable value.

[0022] Furthermore, in step 5, the allowable value is determined by the ship's specifications.

[0023] Furthermore, in step 5, only one target location is checked at a time.

[0024] The beneficial effects of this invention are as follows: By selecting multiple key locations (such as the bow, middle, and stern) within the target section and setting corresponding target values ​​for bending moment and shear force, and through segmented boundary moment adjustment, the bending moment and shear force at each target location can accurately approach the target values. This invention can improve the accuracy and reliability of structural strength assessment, avoid structural safety hazards caused by local bending moment distortion, improve computational efficiency and adaptability, and ensure that the structural strength of the entire target section is comprehensively verified to meet actual engineering requirements. Attached Figure Description

[0025] Figure 1 This diagram illustrates the difference between the adjusted bending moment and the target bending moment, based on the cabin position as the target value in the existing technology.

[0026] Figure 2 The diagram shows a comparison between the bending moment adjusted using the method of this invention and the target bending moment, with the section divided into three target positions as an example. Detailed Implementation

[0027] The present invention will be described more clearly and completely below with reference to a preferred embodiment and the accompanying drawings.

[0028] A method for adjusting the bending moment and shear force at multiple locations in finite element analysis of a ship hull section, comprising:

[0029] Step 1: Perform finite element analysis on the hull section, select multiple target locations in the target section, and set the target values ​​of vertical bending moment and shear force for each target location.

[0030] Step 2: Construct a three-section model, which includes the target section and two sections adjacent to the target section before and after it;

[0031] Step 3, select a target location;

[0032] Step 4: Apply bending moments to the bow and stern faces of the three-section model respectively, so that the shear force and bending moment at the target position are adjusted in the direction of the target value corresponding to the target position.

[0033] Step 5: Compare the adjusted bending moment distribution at the target location with the target value at the target location; check the stress state of the components in the target location area.

[0034] Step 6: Repeat steps 4 and 5 for each of the other target locations.

[0035] The method for adjusting the multi-objective bending moment and shear force of hull sections using finite element analysis in this embodiment includes the following steps:

[0036] 1. Multi-target location selection.

[0037] Finite element analysis was performed on the hull section. Multiple target locations were selected in the target section, and target values ​​for vertical bending moment and shear force were set for each target location.

[0038] In a preferred embodiment, at least three target locations are selected within the target segment. These target locations may include the forward transverse bulkhead of the target segment, the middle of the target segment, or the aft transverse bulkhead of the target segment.

[0039] The target values ​​of vertical bending moment and shear force corresponding to each target location are determined by ship design specifications or by calculation.

[0040] 2. Establish a finite element model for the three compartments.

[0041] A three-section model is constructed, comprising the target section and two sections adjacent to it, one before and one after. This three-section model is used to simulate the actual load transfer path. The model includes the longitudinal members of the hull beams, which include the deck, bottom plate, and side structures.

[0042] 3. Select a target location.

[0043] 4. Apply additional bending moment for adjustment.

[0044] Bending moments are applied to the bow and stern faces of the three-section model to adjust the shear force and bending moment at the target locations toward the target values ​​corresponding to those locations.

[0045] The specific adjustment method includes: assuming the target position is the i-th target position, first obtain the bending moment M caused by the local load. local_loc_i Adjusting the bending moment M by shear force shear_i Adjust the shear force at the target location to the target value, and then apply M. target_loc_i -M local_loc_i -M shear_i Adjust the vertical bending moment to the target value M. target_loc_i .

[0046] 5. Verification and checking.

[0047] Compare the adjusted bending moment distribution at the target location with the target value corresponding to that location to determine the degree of agreement; check the stress state of the components in the target location area. Verify the stress state of the components in the target location area to ensure that the stress state meets the allowable values. Allowable values ​​are determined by ship specifications. Only one target location is checked at a time.

[0048] 6. For each of the other target locations, repeat the "Apply Additional Bending Moment Adjustment" and "Verification and Checking" steps respectively.

[0049] The bending moment adjustment will now be further explained in detail with an example, based on the aforementioned steps.

[0050] In bending moment adjustment, multiple overall longitudinal bending moment adjustment conditions can be established, including condition 1, condition 2... condition n.

[0051] Taking the i-th target position as an example, the bending moment M caused by the local load is obtained. local_loc_i Adjusting the bending moment M by shear force shear_i Adjust the shear force at the target location to the target value, and then apply (M) target_loc_i -M local_loc_i -M shear_i Adjust the vertical bending moment to the target value M. target_loc_i This allows the bending moment and shear force at the target location to be adjusted to the target value to check the strength of adjacent components. See Table 1 for details.

[0052] Table 1 Multi-objective shear force and bending moment adjustment

[0053]

[0054] Taking the division of the compartment into three target locations as an example, a comparison diagram of the bending moment adjusted using the method of this invention and the target bending moment is shown below. Figure 2 As shown.

[0055] Compare Figure 1 and Figure 2 As can be seen, using the multi-target position bending moment adjustment method can make the adjusted bending moment better fit the target bending moment, avoiding a large deviation between the calculation results and the actual working conditions.

[0056] The method of the present invention is an adjustment method based on bending moment at multiple target locations, which can achieve better results in the calculation of sections with large variations in bending moment and shear force.

[0057] In this invention, based on the adjustment of bending moment and shear force at multiple target locations, each calculation result only checks the structural strength of the region adjacent to the target location, ensuring that the bending moment and shear force of the checked structure are close to the target value.

[0058] This invention provides a method for adjusting bending moment and shear force at multiple target locations. By selecting multiple key locations (such as the bow, middle, and stern) of the target section and setting corresponding target values ​​for bending moment and shear force for each location, and by adjusting the boundary bending moment in a segmented manner, the bending moment and shear force at each target location can accurately approach the target values. This invention can improve the accuracy and reliability of structural strength assessment, avoid structural safety hazards caused by local bending moment distortion, improve computational efficiency and adaptability, and ensure that the structural strength of the entire target section is comprehensively verified, meeting the needs of actual engineering projects.

[0059] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for adjusting bending moment and shear force at multiple locations in finite element analysis of a ship hull section, characterized in that, It includes: Step 1: Perform finite element analysis on the hull section, select multiple target locations in the target section, and set the target values ​​of vertical bending moment and shear force for each target location. Step 2: Construct a three-section model, which includes the target section and two sections adjacent to the target section before and after it; Step 3, select a target location; Step 4: Apply bending moments to the bow and stern faces of the three-section model respectively, so that the shear force and bending moment at the target position are adjusted in the direction of the target value corresponding to the target position. Step 5: Compare the adjusted bending moment distribution at the target location with the target value at the target location; check the stress state of the components in the target location area. Step 6: Repeat steps 4 and 5 for each of the other target locations.

2. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 1, characterized in that, In step 1, at least 3 target locations are selected in the target compartment.

3. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 2, characterized in that, The target location includes the forward transverse bulkhead of the target section, or the middle of the target section, or the rear transverse bulkhead of the target section.

4. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 1, characterized in that, In step 1, the target values ​​of vertical bending moment and shear force corresponding to each target location are determined by ship design specifications or by calculation.

5. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 1, characterized in that, In step 2, the three-section model is used to simulate the actual load transfer path.

6. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 1, characterized in that, In step 2, the three-section model includes the longitudinal components of the hull beam, which include the deck, bottom plate, and side structure.

7. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 1, characterized in that, In step 4, the bending moment M caused by the local load is first obtained. localloci Adjusting the bending moment M by shear force shear_i Adjust the shear force at the target location to the target value, and then apply M. target_loc_i -M local_loc_i- M shear_i Adjust the vertical bending moment to the target value M. target_loc_i .

8. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 1, characterized in that, In step 5, the stress state of the components in the target location area is checked to ensure that the stress state meets the allowable value.

9. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 8, characterized in that, In step 5, the allowable value is determined by the ship's specifications.

10. The method for adjusting the bending moment and shear force at multiple locations in finite element calculation of hull sections as described in claim 8, characterized in that, In step 5, only one target location is checked at a time.

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