Material geometric multi-scale optimization design method for stiffened plate of cruise ship cabin

Abstract

The invention relates to a material geometric multi-scale optimization design method of a cruise ship cabin stiffened plate, establishes a secondary optimization design method of a cruise ship cabin type typical stiffened plate structure, regards composite material parameter configuration as a mechanical inverse problem, and improves the degree of freedom of the structural design. The problems existing in the parameter determination aspect of a traditional metal or composite material stiffened plate structure are solved, so that the optimal mechanical parameter combination of the stiffened plate structure is obtained to the maximum extent, and the structural safety of a cruise ship cabin and the comfort of passengers are guaranteed. The method not only can be used for structural design of a cruise ship cabin, but also can provide reference for structural optimization design of other metal and composite material combined stiffened plates.

Description

Technical Field

[0001] The invention relates to the technical field of multi-scale optimization design methods for cruise ship cabin stiffeners, and in particular to a material geometry multi-scale optimization design method for cruise ship cabin stiffeners. Background Art

[0002] The stiffened plate structure is a typical load-bearing structure in engineering with high specific strength and specific stiffness. Using this type of structure as the main structure of the cruise ship cabin can improve the mechanical properties of the system. However, with the gradual increase in the requirements for vibration comfort, noise control, etc. of the cruise ship cabin, and the continuous increase in the lightweight requirements of the overall structure. The laminated structure of metal-based composite materials is a suitable choice as the base plate of the stiffened plate. However, due to the anisotropy of composite materials, how to reasonably configure the thickness of composite materials and metals. Determining the optimal composite material laying method has become a new design problem. Summary of the invention

[0003] In view of the shortcomings in the above-mentioned existing production technologies, the applicant provides a material geometry multi-scale optimization design method for cruise ship cabin stiffened panels, thereby effectively solving the problems existing in parameter determination of traditional metal or composite stiffened panel structures, obtaining the optimal mechanical parameter combination of the stiffened panel structure to the greatest extent, and ensuring the structural safety of the cruise ship cabin and the comfort of passengers; this method can not only be used for the structural design of cruise ship cabins, but can also provide reference for the optimization design of other metal and composite stiffened panel structures.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A material geometry multi-scale optimization design method for cruise ship cabin stiffeners includes the following operation procedures:

[0006] S1: Establish a finite element parametric model of the cruise ship cabin stiffened plate sandwich structure;

[0007] S2: Determine the design variables, constraints and objective function of the stiffened plate sandwich structure;

[0008] S3: Use the global optimization algorithm to solve the optimization design model of the stiffened plate structure and determine the thickness ratio and equivalent material parameters of the metal and composite materials in the sandwich structure;

[0009] S4: Based on the equivalent composite material parameters obtained in S3, optimize the parameters such as the ply angle and ply thickness of the composite material to obtain the configuration of the composite material;

[0010] S5: Bring the optimized composite material parameters into the parametric model of the cruise ship cabin stiffened plate structure to verify the rationality of the optimization results.

[0011] Its further technical solution is:

[0012] S1 includes the following processes:

[0013] S1.1: Separate the typical characteristics of the cruise ship cabin stiffened plate structure and establish a parametric finite element model of the metal-composite laminated stiffened plate structure;

[0014] S1.2: Set the initial parameters of the model and analyze the natural frequency of the stiffened plate structure and the displacement, velocity and acceleration under load excitation.

[0015] S2 includes the following processes:

[0016] S2.1: The perturbation method is used to determine the sensitive parameters in the stiffened plate structure. The candidate parameters include the material of the metal layer, the thickness of the composite layer, and the equivalent material parameters;

[0017] S2.2: According to the design requirements, the sensitive parameters selected in S2.1 are limited to obtain the feasible domain;

[0018] S2.3: With reference to the design specifications and requirements, establish the objective function for the optimal design with the goal of maximizing the fundamental frequency of the structure and minimizing the velocity and displacement acceleration amplitude under load excitation.

[0019] S3 includes the following processes:

[0020] S3.1: The global optimization method used is a genetic algorithm. The input parameters of the optimization method include the material of the metal layer, the thickness of the composite layer, the equivalent material parameters of the composite layer and the composite reinforcement, and the width and thickness of each rib;

[0021] S3.2: During optimization, solve the thickness, material or equivalent material parameters of metals and composite materials to obtain the optimal parameter combination of materials and geometric multi-scales.

[0022] S4 includes the following processes:

[0023] S4.1: A variable control strategy was adopted to obtain 30 sets of data including the elastic modulus E1 of the fiber direction of the single-layer plate, the stacking angle, and the first-order vibration frequency of the model. The griddata package in Python was used for interpolation. Based on the interpolation results, the two key parameters of the composite material, the stacking angle and the fiber matrix, were optimized.

[0024] S4.2: Round the optimized results with reference to relevant standards or specifications.

[0025] In S5, the rounded optimization result parameters are substituted into the parameterized model to solve the frequency. The beneficial effects of the present invention are as follows:

[0026] The present invention breaks through the traditional framework of separate optimization of materials and geometry, and proposes a multi-scale optimization method for the sandwich structure of the cruise ship cabin stiffened plate. The sandwich structure determined based on this method can obtain the best mechanical properties and economy. The characteristic of this method is that it establishes a secondary optimization design method for the typical stiffened plate structure of the cruise ship cabin, regards the parameter configuration of the composite material as an inverse mechanical problem, and improves the degree of freedom of design of this type of structure. The theoretical basis of the present invention is correct and reliable, the design steps are clearly divided into levels, and the design calculation process can be completed on a high-performance computer platform relying on finite element software and intelligent optimization algorithms. The multi-scale optimization design method proposed in the present invention solves the problem of independent optimization of materials and geometry of complex stiffened plate structures, and can achieve the best fit between materials and structural dimensions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of a typical stiffened plate of the present invention.

[0028] Figure 2 It is a typical stiffened plate finite element calculation model of the present invention.

[0029] Figure 3 It is a schematic diagram of the variation of the first-order frequency of the reinforced double-layer plate after the optimization parameters are perturbed by 10% respectively according to the present invention.

[0030] Figure 4 It is a frequency variation curve diagram during the frequency optimization process using genetic algorithm in the present invention.

[0031] Figure 5 It is a curve diagram of the changes in the three parameters (steel plate thickness) that have the greatest impact on the first-order frequency of the double-layer plate reinforced structure during the optimization process of the present invention.

[0032] Figure 6 It is a curve diagram of the changes in the three parameters (carbon fiber plate thickness) that have the greatest impact on the first-order frequency of the double-layer plate reinforced structure during the optimization process of the present invention.

[0033] Figure 7 It is a curve diagram of the changes in the optimization process of the three parameters (in-plane elastic modulus of the carbon fiber plate) that have the greatest influence on the first-order frequency of the double-layer plate reinforced structure of the present invention.

[0034] Figure 8 It is a three-dimensional surface that characterizes the relationship between the tensile modulus of the carbon fiber single-layer plate, the stacking angle of the carbon fiber single-layer plate and the first-order vibration frequency of the structure in the present invention.

[0035] Fig. 9 It is a schematic diagram of the actual plying of the carbon fiber plate of the present invention. DETAILED DESCRIPTION

[0036] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0037] like Figure 1-Figure 9 As shown, the material geometry multi-scale optimization design method of the cruise ship cabin stiffener of this embodiment includes the following operation process:

[0038] S1: Establish a finite element parametric model of the cruise ship cabin stiffened plate sandwich structure;

[0039] S2: Determine the design variables, constraints and objective function of the stiffened plate sandwich structure;

[0040] S3: Use the global optimization algorithm to solve the optimization design model of the stiffened plate structure and determine the thickness ratio and equivalent material parameters of the metal and composite materials in the sandwich structure;

[0041] S4: Based on the equivalent composite material parameters obtained in S3, optimize the parameters such as the ply angle and ply thickness of the composite material to obtain the configuration of the composite material;

[0042] S5: Bring the optimized composite material parameters into the parametric model of the cruise ship cabin stiffened plate structure to verify the rationality of the optimization results.

[0043] S1 includes the following processes:

[0044] S1.1: Separate the typical characteristics of the cruise ship cabin stiffened plate structure and establish a parametric finite element model of the metal-composite laminated stiffened plate structure;

[0045] S1.2: Set the initial parameters of the model and analyze the natural frequency of the stiffened plate structure and the displacement, velocity and acceleration under load excitation.

[0046] S2 includes the following processes:

[0047] S2.1: The perturbation method is used to determine the sensitive parameters in the stiffened plate structure. The candidate parameters include the material of the metal layer, the thickness of the composite layer, and the equivalent material parameters;

[0048] S2.2: According to the design requirements, the sensitive parameters selected in S2.1 are limited to obtain the feasible domain;

[0049] S2.3: With reference to the design specifications and requirements, establish the objective function for the optimal design with the goal of maximizing the fundamental frequency of the structure and minimizing the velocity and displacement acceleration amplitude under load excitation.

[0050] 3 includes the following processes:

[0051] S3.1: The global optimization method used is a genetic algorithm. The input parameters of the optimization method include the material of the metal layer, the thickness of the composite layer, the equivalent material parameters of the composite layer and the composite reinforcement, and the width and thickness of each rib;

[0052] S3.2: During optimization, solve the thickness, material or equivalent material parameters of metals and composite materials to obtain the optimal parameter combination of materials and geometric multi-scales.

[0053] S4 includes the following processes:

[0054] S4.1: A variable control strategy was adopted to obtain 30 sets of data including the elastic modulus E1 of the fiber direction of the single-layer plate, the stacking angle, and the first-order vibration frequency of the model. The griddata package in Python was used for interpolation. Based on the interpolation results, the two key parameters of the composite material, the stacking angle and the fiber matrix, were optimized.

[0055] S4.2: Round the optimized results with reference to relevant standards or specifications.

[0056] In S5, the rounded optimization result parameters are substituted into the parameterized model to solve the frequency.

[0057] Embodiment 1:

[0058] Step 1: Analyze the structural characteristics of the optimized double-layer stiffened plate, such as Figure 1 As shown, the length and width of the reinforced plate are both 500m, and the total thickness of the double-layer plate is 8mm. The thickness of the carbon fiber composite plate and the steel plate is initially set to be the same 4mm. The cross-sectional shape of the added reinforcement is rectangular, and the width of each rib is initially set to 7mm and the height is 10mm. The overall structure is a carbon fiber composite plate, a steel plate, and a carbon fiber composite reinforcement from bottom to top. Among them, the carbon fiber material parameters used for the base plate and the reinforcement are considered different and will be optimized as two independent sets of variables. All optimized parameters include both geometry and materials. The geometric parameters include the thickness of the carbon fiber plate and the steel plate, and the width and thickness of the reinforcement. The material parameters include the in-plane elastic modulus, lateral elastic modulus, in-plane Poisson's ratio, lateral Poisson's ratio and shear modulus of the carbon fiber base plate and the carbon fiber reinforcement. The established finite element analysis model is shown as follows Figure 2 shown.

[0059] max:F(X)=f(x1,x2,x3,x4,x5,x6,x7,x8,x9,x 10 )

[0060] x1—steel plate thickness, 0≤x1≤8

[0061] x2—composite material plate thickness, x2=8-x1

[0062] x3—elastic modulus of composite material board surface, 130000≤x3≤160000

[0063] x4—elastic modulus of composite material plate in thickness direction, 5000≤x4≤7000

[0064] x5—Poisson’s ratio within the composite material plate, 0.2≤x5≤0.3

[0065] x6—Shear modulus of composite material plate, 4000≤x6≤5000

[0066] x7—Rectangular rib width, 2≤x7≤10

[0067] x8—rectangular rib thickness, 7≤x8≤25

[0068] x9—elastic modulus of rectangular reinforcement surface, 130000≤x9≤160000

[0069] x 10 —Rectangular reinforcement shear modulus, 4000≤x 10 ≤5000

[0070] Step 2: First, calculate the first-order vibration frequency of the original model. Then, based on the perturbation method, increase each parameter to be optimized by 10% on the basis of the original model, calculate the first-order vibration frequency of the double-layer plate reinforced structure, compare the obtained frequency with the initial vibration frequency, and calculate the percentage value of the change. In this way, the influence of each parameter to be optimized on the vibration frequency of the structure is obtained. Figure 3 The analysis results shown here remove the parameters that have zero effect on the structural vibration frequency.

[0071] Step 3: Take all the parameters listed in step 1 as input features, and the double-layer plate reinforced structure as the target feature, and optimize based on the genetic algorithm. The frequency change curve during the optimization process is shown in Figure 4 The change curves of the three parameters (composite plate thickness, steel plate thickness, and composite plate in-plane stiffness) that have the greatest impact on the first-order frequency of the double-layer plate reinforced structure during the optimization process are shown in Figure 1. Figure 5 , Figure 6 , Figure 7 As shown in the figure, the optimized size parameters are rounded.

[0072] Step 4: Take the strategy of controlling variables to obtain 30 sets of data including the elastic modulus E1 of the fiber direction of the single-layer board, the stacking angle and the first-order vibration frequency of the model, and use the griddata package in python to interpolate. Based on the interpolation results, the two key parameters of the composite material, the stacking angle and the fiber base, are optimized. The interpolation results are visualized as a three-dimensional surface, such as Figure 8 shown.

[0073] Step 5: Use the rounded composite fiber direction elastic modulus and ply angle to replace the original equivalent elastic modulus in the engineering constant format, and calculate the results of the updated finite element model to verify whether the ply method and carbon fiber material parameters used are consistent with the optimization results. Fig. 9 As shown, the total number of layers is n=30, the thickness of each layer is 0.2 mm, and 0° / 90° alternating ply is adopted.

[0074] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any form of modification may be made within the scope of protection of the present invention.

Claims

1. A material geometry multi-scale optimization design method for cruise ship cabin stiffeners, characterized by: The following operation procedures are included: S1: Establish a finite element parametric model of the cruise ship cabin stiffened plate sandwich structure; S2: Determine the design variables, constraints and objective function of the stiffened plate sandwich structure; S3: Use the global optimization algorithm to solve the optimization design model of the stiffened plate structure and determine the thickness ratio and equivalent material parameters of the metal and composite materials in the sandwich structure; S4: Based on the equivalent composite material parameters obtained in S3, optimize the parameters such as the ply angle and ply thickness of the composite material to obtain the configuration of the composite material; S5: Bring the optimized composite material parameters into the parametric model of the cruise ship cabin stiffened plate structure to verify the rationality of the optimization results.

2. A material geometry multi-scale optimization design method for cruise ship cabin stiffeners according to claim 1, characterized in that: S1 includes the following processes: S1.1: Separate the typical characteristics of the cruise ship cabin stiffened plate structure and establish a parametric finite element model of the metal-composite laminated stiffened plate structure; S1.2: Set the initial parameters of the model and analyze the natural frequency of the stiffened plate structure and the displacement, velocity and acceleration under load excitation.

3. The material geometry multi-scale optimization design method for cruise ship cabin stiffeners according to claim 1, characterized in that: S2 includes the following processes: S2.1: The perturbation method is used to determine the sensitive parameters in the stiffened plate structure. The candidate parameters include the material of the metal layer, the thickness of the composite layer, and the equivalent material parameters; S2.2: According to the design requirements, the sensitive parameters selected in S2.1 are limited to obtain the feasible domain; S2.3: With reference to the design specifications and requirements, establish the objective function for the optimal design with the goal of maximizing the fundamental frequency of the structure and minimizing the velocity and displacement acceleration amplitude under load excitation.

4. The material geometry multi-scale optimization design method for cruise ship cabin stiffeners according to claim 1, characterized in that: S3 includes the following processes: S3.1: The global optimization method used is a genetic algorithm. The input parameters of the optimization method include the material of the metal layer, the thickness of the composite layer, the equivalent material parameters of the composite layer and the composite reinforcement, and the width and thickness of each rib; S3.2: During optimization, solve the thickness, material or equivalent material parameters of metals and composite materials to obtain the optimal parameter combination of materials and geometric multi-scales.

5. The material geometry multi-scale optimization design method for cruise ship cabin stiffeners according to claim 1, characterized in that: S4 includes the following processes: S4.1: A variable control strategy was adopted to obtain 30 sets of data including the elastic modulus E1 of the fiber direction of the single-layer plate, the stacking angle, and the first-order vibration frequency of the model. The griddata package in Python was used for interpolation. Based on the interpolation results, the two key parameters of the composite material, the stacking angle and the fiber matrix, were optimized. S4.2: Round the optimized results with reference to relevant standards or specifications.

6. The material geometry multi-scale optimization design method for cruise ship cabin stiffeners according to claim 1, characterized in that: In S5, the rounded optimization result parameters are substituted into the parameterized model to solve the frequency.

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