Method for determining minimum-weight marine lamp holder

Abstract

According to the method for determining the minimum-weight marine lamp bracket, the reliability of the lamp bracket structure is evaluated according to the two indexes of the strength characteristic and the vibration characteristic of the lamp bracket structure, and the lamp bracket is finely designed according to the characteristics of the lamp bracket structure. According to the method, the proxy model is introduced into the lamp holder with the reinforced complex structure, bending stress and first-order inherent frequency of input structure parameters and output parameters in an uninterpretable original model are converted into analyzable mathematical formulas, structural optimization design of the lamp holder with the reinforced structure is carried out through the genetic algorithm, computing resources are saved, the design period is shortened, and the design efficiency is improved. Compared with a non-reinforced lamp bracket structure, a reasonable design of the marine lamp bracket is finally realized by combining the weight of the marine lamp bracket with a construction process, so that the problem of contradiction between the design cost and the reliability of the marine lamp bracket is solved, and a key technical support is provided for high-quality development of the ship industry.

Description

Technical Field

[0001] This invention belongs to the field of marine shipbuilding and design, and specifically relates to a method for determining the minimum weight of a marine light fixture. Background Technology

[0002] With the increase in tonnage and the increasingly compact hull structure of modern ships, it is particularly important to optimize the structural design of outfitting components to reduce their weight while meeting the load-bearing capacity requirements, in order to help ships reduce emissions and manufacturing costs.

[0003] Marine lighting fixtures, as a crucial component of outfitting, play a key role in shipbuilding and daily operation. Given their large number and significant weight load, current marine lighting fixture designs are largely based on experience, lacking corresponding technical references. These fixtures suffer from high structural redundancy, insufficient vibration resistance, and high maintenance costs. Furthermore, suitable modification plans are often unavailable when problems arise, and design cycles are lengthy. Therefore, a design method for marine lighting fixtures that shortens the design cycle, enhances structural reliability, and reduces weight and costs is urgently needed. This method would allow for strength and vibration assessments of the fixtures at the initial design stage, meeting shipowners' safety requirements while also reducing weight and costs.

[0004] Marine lighting rig structures include the main beam, the lamp, marine cables, and reinforcement. Determining the rationality of a marine lighting rig structure requires simultaneously meeting strength and vibration requirements. Excessive bending stress can lead to breakage at the base or joints of the rig, while structural instability can cause resonance with the ship's engine and other vibration sources, resulting in structural fatigue failure. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for determining the minimum weight of a marine light fixture, aiming to ensure that the marine light fixture meets strength and vibration requirements. The method employed is as follows: A method for determining the minimum weight of a marine light fixture, the specific method is as follows: When no reinforcing structure is installed between the light fixture and the hull: S1: Set the initial variable for the diameter of the main beam of the lamp holder to D1=30mm, and the initial variable for the wall thickness of the main beam of the lamp holder to H1=2mm. When installing from the top, consider that the distance between the lamp holder and the bottom of the deck is 2400mm to determine the length of the main beam of the lamp holder. When installing from the wall, consider the illumination area of ​​the lamp and the length of the main beam of the lamp holder to 800mm≤L1≤1500mm.

[0006] S2: Perform stress assessment when B1≤0.6*σ y If the strength requirements are met, proceed to the next step.

[0007] When B1 > 0.6*σ yIf the strength requirements are not met, the wall thickness H1 of the main beam of the lamp holder will be increased by 0.2mm, and stress assessment will continue.

[0008] Wherein, B1 is the bending stress of the lamp holder structure.

[0009] σ y The yield strength of the main beam of the lamp holder.

[0010] S3: Calculate the first natural frequency M1 of the lamp holder structure, and calculate the excitation frequency M of the host machine. .

[0011] Among them, CSR RPM The main engine speed is (r / min).

[0012] 'a' represents the number of propeller blades; S4: Conduct a vibration assessment. When M1 ≥ 1.5 * M, the vibration requirements are met.

[0013] When M1 < 1.5 * M, the vibration requirements are not met. The diameter D1 of the main beam of the lamp holder is increased by 2 mm, and stress and vibration assessments are continued until the strength and vibration requirements are met.

[0014] Obtain the required main beam diameter D 1n and wall thickness H 1n ; S5: Based on the length L1 and diameter D of the main beam of the lamp holder 1n and wall thickness H 1n Calculate the weight W of the lamp holder. B1 =f1(D 1n H 1n The specific formula is as follows: (L1) W B1 =7850*pi*(2*D1*H1-H1^2) / 4*L1.

[0015] When a reinforcing structure is installed between the light fixture and the hull: S6: Based on the initial variables D1 (diameter of the main beam of the lamp holder) and H1 (wall thickness) in S1, set the number of reinforcing structures N and the length L of the reinforcing structures. S The angle θ of the reinforcing structure, the diameter D2 of the reinforcing structure, and the wall thickness H2 of the reinforcing structure.

[0016] S7: Generate a sample space using the Latin hypercube method based on the variables in S6, and construct a surrogate model for the lamp holder.

[0017] S8: Add new sample points by generating new sample points using the maximum expectation criterion to improve the sample space.

[0018] S9: Set the number of iterations Z. If the number of iterations Z is not met, generate new sample points and return to the sample space to continue building the lamp holder proxy model until the number of iterations Z is reached, and then proceed to the next step.

[0019] S10: Fitting the bending stress B2=f of the lamp holder with reinforced structure based on the constructed surrogate model. 21 (D1,H1,N,L S (θ, D2, H2) and the first natural frequency M2 = f 22 (D1,H1,N,L S ,θ,D2,H2).

[0020] S11: Determine the objective function W B2 =f2(D1,H1,N,L S The relationship between θ, D2, and H2 is as follows: W B2 =7850*pi*(2*D1*H1-H1^2) / 4*L1+7850*pi*(2*D2*H2-H2^2) / 4* L S / cos(θ)*N.

[0021] Determine the stress constraint T1: B2≤0.6*σy.

[0022] Vibration constraint T2: M2≥1.5*M.

[0023] Structural constraint T3: D2≤0.5*D1.

[0024] S12: Optimize using a genetic algorithm, outputting the weight W of the lamp holder. B2m Main beam diameter D 1m Wall thickness H 1m Number of reinforced structures N m Length L Sm Angle θ m The diameter D of the reinforced structure 2m and wall thickness H 2m ; S13: Introduce construction process weight P. .

[0025] Select the option using the following formula: ; When Weight < 0, choose the scheme without reinforcement.

[0026] When Weight ≥ 0, choose the scheme with reinforcement structure.

[0027] The method for determining the minimum weight of a marine light fixture described above further includes wall-mounted light fixtures and ceiling-mounted light fixtures.

[0028] Furthermore, in the above-mentioned method for determining the minimum weight of a marine lamp holder, one end of the wall-mounted lamp holder is welded and fixed to the hull, and the hull has reinforcing ribs to improve structural stability.

[0029] Furthermore, in the aforementioned method for determining the minimum weight of a marine light fixture, the top-mounted light fixture is welded and suspended from the hull of the ship or from a T-beam.

[0030] The above method for determining the minimum weight of a marine light fixture further specifies that the weight of the light is 2 kg to 30 kg.

[0031] Furthermore, in the method for determining the minimum weight of a marine light fixture described above, the yield strength of the main beam of the light fixture is determined based on the material of the main beam.

[0032] Furthermore, the method for determining the minimum weight of a marine light fixture described above, when the reinforcement structure is located on the main beam, has a position where 0.5*L1≤L S ≤L1, the maximum number of reinforcing structures N is 2, the angle θ of the reinforcing structure is between 30° and 45°, the two reinforcing structures are located in the same position, and the diameter D2 of the reinforcing structure is not greater than 0.5*D1.

[0033] Among them, L S To reinforce the location of the structure.

[0034] L1 is the length of the main beam of the lamp holder.

[0035] Furthermore, in step S9 of the method for determining the minimum weight marine light fixture described above, the number of iterations for dot-matrix addition is Z=50.

[0036] This invention introduces a proxy model for lamp holders with reinforced complex structures, transforming the input structural parameters and output parameters (bending stress and first-order natural frequency) from the uninterpretable original model into analyzable mathematical formulas. A genetic algorithm is then used for the structural optimization design of reinforced lamp holders, saving computational resources and shortening the design cycle. A comparison is made with unreinforced lamp holder structures using a criterion combining marine lamp holder weight and construction technology, ultimately achieving a reasonable marine lamp holder design. This solves the contradiction between cost and reliability in marine lamp holder design, providing key technical support for the high-quality development of the shipbuilding industry. Attached Figure Description

[0037] Figure 1 It is a wall-mounted lamp holder without reinforcement. Figure 2 It is a top-mounted lamp holder without reinforcement. Figure 3 It is a wall-mounted lamp holder with a reinforced structure; Figure 4 It is a top-mounted lamp holder with a reinforced structure; Among them, 1-lighting frame main beam, 2-hull, 3-reinforcing rib, 4-reinforcing structure. Detailed Implementation

[0038] The present invention will be described in detail with reference to specific embodiments.

[0039] like Figure 1 and 2 The method shown is for determining the minimum weight of a marine light fixture. Depending on the application scenario, the type of light fixture can be either a wall-mounted light fixture or a ceiling-mounted light fixture. Wall-mounted light fixtures are welded and fixed to the hull at one end, with reinforcing ribs on the hull to improve structural stability. Ceiling-mounted light fixtures are welded and suspended from the ceiling; they can be welded to the hull or to a T-beam.

[0040] There are many types of lights on ships, and their weight ranges from 2 kg to 30 kg. The weight (W) of a light can be determined by consulting the technical manual, depending on its type. L The height of the light fixture, between 2.2m and 2.4m from the ground, balances lighting and spatial layout. The length of the ceiling-mounted light fixture is determined by both its height from the ground and the ceiling height, while the length of the wall-mounted light fixture is determined based on the spatial layout and functional requirements. Thus, the length L1 of the light fixture can be determined. The cable is fixed to the main beam and connected to the light. The cable density is 210kg / km. The weight W of the cable is calculated based on the length of the main beam. C =0.21*L1, the distributed quality is centralized, and the cable is concentrated at 0.75*L1.

[0041] In the case of no reinforced structure, such as Figure 1 , 2 As shown, wall-mounted and ceiling-mounted light fixtures without reinforcement structures.

[0042] Design variable: main beam diameter D1.

[0043] The design variable is the wall thickness H1 of the main beam of the lamp holder.

[0044] Calculate the bending stress B1 of the lamp holder structure, and determine the yield strength σ of the main beam of the lamp holder based on the material of the main beam. y .

[0045] Perform stress assessment when B1 ≤ 0.6*σ y If the strength requirement is met, proceed to the next step. If B1 > 0.6*σ y The strength requirements are not met, so the wall thickness H1 of the main beam of the lamp holder is increased by 0.2mm, and stress assessment is continued.

[0046] The first natural frequency M1 of the lamp holder structure and the excitation frequency M of the host are calculated using the following formulas: .

[0047] In the formula, M is the natural frequency of the first-order mode, and the part to the right of the less than sign is the excitation frequency of the host. CSR RPM denoted as 'rotor speed' (r / min), and 'a' as the number of propeller blades.

[0048] A vibration assessment is conducted. If M1 ≥ 1.5 * M, the vibration requirement is met. If M1 < 1.5 * M, the vibration requirement is not met. The diameter D1 of the main beam of the lamp holder is increased by 2 mm, and stress and vibration assessments are continued until the requirement is met.

[0049] Output parameter: Main beam diameter D 1n and wall thickness H 1n .

[0050] Based on the length L1 and diameter D of the main beam of the lamp holder 1n and wall thickness H 1n Calculate the weight W of the lamp holder. B1 = f 1(D 1n H 1n The specific formula is as follows: W (L1) B1 =7850*pi*(2*D1*H1-H1^2) / 4*L1 Cases with reinforced structures, such as Figure 3 , 4 The wall-mounted and ceiling-mounted light fixtures shown are reinforced structural forms.

[0051] Location of the reinforced structure L S The number of reinforcing structures (N), their diameter (D2), wall thickness (H2), and angle (θ) of the reinforcing structures all have a certain impact on the strength and vibration of the lamp holder structure. The reinforcing structures are located on the main beam, at a position where 0.5*L1 ≤ L. S ≤L1, the maximum number of reinforcing structures N is 2, the angle θ of the reinforcing structure is between 30° and 45°, and when there are two reinforcing structures, the reinforcing structures are located in the same position. The diameter D2 of the reinforcing structure material cannot be greater than 0.5*D1. Design variables include the diameter D1 and wall thickness H1 of the main beam of the lamp holder, the number N of reinforcing structures, and the length L. S Angle θ, strengthen the structural diameter D2 and wall thickness H2.

[0052] When there are many design variables, mesh optimization has significant drawbacks and a long design cycle. Surrogate models can reduce computational costs and improve optimization efficiency while maintaining a certain level of accuracy. The sample space is generated using a Latin hypercube approach based on the defined design variables, avoiding over-design.

[0053] Construct a proxy model for the light fixture.

[0054] The points in the sample space are insufficient to describe the relationship between the design variables and the objective, so additional sample points are needed to supplement them. The maximum expectation criterion is used to generate new sample points to improve the sample space.

[0055] The design adds a point-based iteration count of Z=50. When the iteration count Z is not met, new sample points are generated and returned to the sample space to continue building the lamp holder proxy model until the iteration count Z is reached, and then proceed to the next step. The larger Z is, the more iterations are needed and the more accurate the proxy model becomes.

[0056] Based on the constructed surrogate model, the bending stress B2 of the reinforced lamp holder structure is fitted. f 21 (D1,H1,N,L S (θ, D2, H2) and first-order natural frequency M2 = f 22 (D1,H1,N,L S Determine the objective function W (θ, D2, H2). B2 = f 2(D1,H1,N,L S The relationship between θ, D2, and H2 is as follows: W B2 =7850*pi*(2*D1*H1-H1^2) / 4*L1+7850*pi*(2*D2*H2-H2^2) / 4* L S / cos(θ)*N; Determine the stress constraint T1: B2≤0.6*σ y Vibration constraint T2: M2≥1.5*M, T3: Structural constraint D2≤0.5*D1.

[0057] The optimal solution is found using a genetic algorithm, and the weight W of the lamp holder is output. B2m Main beam diameter D 1m Wall thickness H 1m Number of reinforced structures N m Length L Sm Angle θ m Strengthen the structural diameter D 2m and wall thickness H 2m。

[0058] S3: Introduce a construction process weight P, which is related to the number of reinforced structures and the welding process, as shown in the following formula: .

[0059] Select the option using the following formula: .

[0060] When Weight < 0, select the unreinforced structure scheme; when Weight ≥ 0, select the reinforced structure scheme.

Claims

1. A method for determining the minimum weight of a marine light fixture, characterized in that, The specific determination method is as follows: When no reinforcing structure is installed between the light fixture and the hull: S1: Set the initial variable D1=30mm for the diameter of the main beam of the lamp holder and the initial variable H1=2mm for the wall thickness of the main beam of the lamp holder. When the lamp holder is installed on the top, the distance from the bottom of the deck to the lamp holder is 2400mm. When the lamp holder is installed on the wall, the lamp holder main beam length is 800mm≤L1≤1500mm, considering the lamp illumination area. S2: Perform stress assessment when B1≤0.6*σ y If the strength requirements are met, proceed to the next step; When B1 > 0.6*σ y If the strength requirements are not met, the wall thickness H1 of the main beam of the lamp holder will be increased by 0.2mm, and stress assessment will continue. Wherein, B1 is the bending stress of the lamp holder structure; σ y The yield strength of the main beam of the lamp holder; S3: Calculate the first natural frequency M1 of the lamp holder structure, and calculate the excitation frequency M of the host machine. ； Among them, CSR RPM The main engine speed (r / min); 'a' represents the number of propeller blades; S4: Conduct a vibration assessment. If M1 ≥ 1.5 * M, the vibration requirements are met. When M1 < 1.5 * M, the vibration requirements are not met. The diameter D1 of the main beam of the lamp holder is increased by 2 mm, and stress and vibration assessments are continued until the strength and vibration requirements are met. Obtain the required main beam diameter D 1n and wall thickness H 1n ; S5: Based on the length L1 and diameter D of the main beam of the lamp holder 1n and wall thickness H 1n Calculate the weight W of the lamp holder. B1 =f1(D 1n H 1n The specific formula is as follows: (L1) IN B1 =7850*pi*(2*D1*H1-H1^2) / 4*L1; When a reinforcing structure is installed between the light fixture and the hull: S6: Based on the initial variables D1 (diameter of the main beam of the lamp holder) and H1 (wall thickness) in S1, set the number of reinforcing structures N and the length L of the reinforcing structures. S The angle θ of the reinforcing structure, the diameter D2 of the reinforcing structure, and the wall thickness H2 of the reinforcing structure; S7: Generate a sample space using the Latin hypercube method based on the variables in S6, and construct a proxy model for the lamp holder; S8: Add new sample points by generating new sample points using the maximum expectation criterion to improve the sample space; S9: Set the number of iterations Z. If the number of iterations Z is not met, generate new sample points and return to the sample space to continue building the lamp holder proxy model until the number of iterations Z is reached, and then proceed to the next step. S10: Fitting the bending stress B2=f of the lamp holder with reinforced structure based on the constructed surrogate model. 21 (D1,H1,N,L S (θ, D2, H2) and the first natural frequency M2 = f 22 (D1,H1,N,L S ,θ,D2,H2); S11: Determine the objective function W B2 =f2(D1,H1,N,L S The relationship between θ, D2, and H2 is as follows: W B2 =7850*pi*(2*D1*H1-H1^2) / 4*L1+7850*pi*(2*D2*H2-H2^2) / 4* L S / cos(θ)*N; Determine the stress constraint T1: B2≤0.6*σy; Vibration constraint T2: M2 ≥ 1.5 * M; Structural constraint T3: D2≤0.5*D1; S12: Optimize using a genetic algorithm, outputting the weight W of the lamp holder. B2m Main beam diameter D 1m Wall thickness H 1m Number of reinforced structures N m Length L Sm Angle θ m The diameter D of the reinforced structure 2m and wall thickness H 2m ; S13: Introduce construction process weight P. ； Select the option using the following formula: ; When Weight < 0, choose the scheme without reinforcement. When Weight ≥ 0, choose the scheme with reinforcement structure.

2. The method for determining the minimum weight marine light fixture according to claim 1, characterized in that, Light fixtures include wall-mounted light fixtures and ceiling-mounted light fixtures.

3. The method for determining the minimum weight marine light fixture according to claim 2, characterized in that, One end of the wall-mounted lamp holder is welded and fixed to the hull, which has reinforcing ribs to improve structural stability.

4. The method for determining the minimum weight marine light fixture according to claim 2, characterized in that, The ceiling light fixtures are welded and suspended from the hull of the ship or from the T-beam.

5. The method for determining the minimum weight marine light fixture according to claim 1, characterized in that, The lamp weighs between 2kg and 30kg.

6. The method for determining the minimum weight marine light fixture according to claim 1, characterized in that, The yield strength of the main beam of the lamp holder is determined based on the material of the main beam.

7. The method for determining the minimum weight marine light fixture according to claim 1, characterized in that, When the reinforcement structure is located on the main beam, the location is 0.5*L1≤L S ≤L1, the maximum number of reinforcing structures N is 2, the angle θ of the reinforcing structure is between 30° and 45°, the two reinforcing structures are located in the same position, and the diameter D2 of the reinforcing structure is not greater than 0.5*D1; Among them, L S To reinforce the location of the structure; L1 is the length of the main beam of the lamp holder.

8. The method for determining the minimum weight marine light fixture according to claim 1, characterized in that, In step S9, the number of iterations for dot-mapping is Z=50.

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