Method and system for designing universal reduced scale model of hull beam considering ultimate bending bearing capacity and buckling failure mode

Abstract

The invention discloses a hull beam universal scale model design method and system considering the ultimate bending bearing capacity and a buckling failure mode, and belongs to the field of hull beam design. The problem that the similarity criterion cannot be met due to the fact that a distortion model is simply designed according to the scale ratio in the prior art is solved. The method comprises the following steps: constructing a similarity criterion of ship body beam bending load; the number of the reinforcing ribs is adjusted to achieve local flexibility coefficient similarity, and the number of the reinforcing ribs in the reduced scale model is obtained; the similarity of beam column flexibility coefficients is realized by correcting the length of a plate grid in the reduced scale model or the distance between strong components; recombining the arrangement directions of the ribs on the bottom plate and the deck to obtain a similarity difference range of different section characteristics; selecting a model with the best ultimate bearing capacity similarity effect as a reference model; balancing the strength of the deck and the bottom plate on the basis of the ultimate bearing capacity difference of the reference model; adjusting the thickness of the similar plate or the reinforcing rib to ensure the similarity between the height of the neutral axis and the inertia moment, and completing the design of the reduced scale model. The method is applied to ship fields.

Description

Technical Field

[0001] The present invention belongs to the field of hull girder design, and particularly relates to a design method for a general scale model of a hull girder considering ultimate bending load-carrying capacity and buckling failure modes. Background Art

[0002] The ultimate bending moment is one of the important mechanical parameters for evaluating the load-carrying capacity of a ship structure, and it directly affects the safety and performance of the ship. With the continuous expansion of the scale of modern civilian ships, especially the increasing size of container ships, the problem of the ultimate load-carrying capacity of the hull has become particularly urgent. Container ships usually have a slender hull shape and a small block coefficient, which results in the buoyancy in the middle of the hull playing a dominant role in the overall stability of the ship. In addition, the relatively uniform distribution of the weight of the cargo and the empty ship is considered in the design of such ships, which also makes the bending load occupy an important position in the ship structure, especially when the hull girder is stressed.

[0003] For example, the famous container ship "MOL Comfort" suffered a serious accident of hull fracture failure due to insufficient load-carrying capacity in the mid-ship area under the action of the ultimate bending moment in the hogging condition. Therefore, understanding and mastering the characteristics of the ultimate load-carrying capacity of the hull girder under bending loads is crucial for the reasonable design of ship structures and ensuring the safety of ships under different working conditions. This usually requires a combination of numerical simulation and experimental research to accurately obtain the ultimate load-carrying failure behavior and the evaluation of the ultimate load-carrying capacity of the hull girder.

[0004] However, conducting the ultimate load-carrying capacity test on a full-scale hull girder faces high economic costs in reality, and it is also difficult to guarantee the test loading conditions. In addition, there are many challenges in the measurement during the experiment. In contrast, using a scale model test is a more economical and effective option. In this kind of test, by establishing a reasonable scale model to simulate the stress and deformation characteristics of the hull girder, the ultimate load-carrying capacity and failure behavior of the prototype ship can be predicted more accurately. Therefore, establishing a high-precision and simple scale model design method, especially applicable to the typical double-bottom hull girder structure, is of great significance for replacing the full-scale test.

[0005] To ensure the feasibility and economy of the test, the design of the scaled model usually sets a relatively low scale ratio for the geometric dimensions to ensure appropriate scaling effects during the test, while setting a relatively high scale ratio for the plate thickness to meet the technological requirements of manufacturing and processing. This gives rise to the so-called distorted model design requirement, that is, unequal scaling is adopted between the geometric shape and the plate thickness of the scaled model. Although this distorted model design can reduce the test cost and complexity, if designed only according to a simple scale ratio, it often fails to meet the similarity criteria, resulting in the test results of the model being unable to accurately reflect the load-bearing capacity and failure characteristics of the prototype hull girder under the action of the ultimate bending moment.

[0006] Therefore, it is particularly important to study and establish a general scaled model design method for hull girders under bending loads that is both universal and accurate. This method can not only effectively improve the similarity and reliability of the scaled model test, but also provide reliable data support for the safety design of ship structures on the basis of ensuring the consistency between the test results and the prototype ship structure. In this context, the 2024 paper "An improved scaled model design method for box girders under hogging moment considering the ultimate bending moment and collapse modes" proposed an improved scaled model design method for hull girders under hogging bending loads. However, this method does not fully consider how to ensure the similarity of the same scaled model in reflecting the vertical ultimate load-bearing characteristics of the prototype hull girder. Therefore, in order to more accurately evaluate the ultimate load-bearing capacity of ship structures, it is urgent to further improve the scaled model design method so that it can comprehensively consider the similarity problems under different working conditions, thereby more accurately predicting the ultimate load-bearing capacity of the prototype hull girder. Summary of the Invention

[0007] In view of this, the present invention aims to propose a general scaled model design method for hull girders considering the ultimate bending load-bearing capacity and buckling failure modes, so as to solve the problem that the existing distorted model designed simply according to the scale ratio fails to meet the requirements of the similarity criteria, resulting in the results of the distorted model being unable to accurately reflect the ultimate load-bearing failure characteristics of the prototype.

[0008] To achieve the above object, the present invention adopts the following technical solutions: A general scaled model design method for hull girders considering the ultimate bending load-bearing capacity and buckling failure modes, the method comprising:

[0009] Step S1: Construct the similarity criteria for the bending load of the hull girder;

[0010] Step S2: Adjust the number of stiffeners to achieve similarity in the flexibility coefficient of the local plate, and obtain the number of stiffeners in the scaled model;

[0011] Step S3: Determine the parameters of the scaled model;

[0012] Step S4: Achieve similarity in the flexibility coefficient of the beam-column by correcting the length of the plate grid or the spacing between two adjacent transverse stiffeners in the scaled model;

[0013] Step S5: Recombine the arrangement directions of the ribs on the bottom plate and the deck to obtain the similarity difference range of different cross-sectional characteristics;

[0014] Step S6: Select the model with the best similarity effect of ultimate bearing capacity as the reference model;

[0015] Step S7: Balance the strength of the deck and the bottom plate based on the similarity differences in the midship ultimate bearing capacity and the hogging ultimate bearing capacity of the reference model;

[0016] Step S8: Adjust the thickness of the similar plate or stiffener to simultaneously meet the similarity differences in the neutral axis height and the moment of inertia, and complete the design of the scaled model.

[0017] Furthermore, an optimization method is also proposed. The step S1 includes: the strength similarity criterion for the local stiffened plate structure and the strength similarity criterion for the hull girder structure.

[0018] Furthermore, an optimization method is also proposed. The number of stiffeners in the scaled model in step S2 includes:

[0019]

[0020] where N s is the number of stiffeners in the scaled model, N p is the number of stiffeners in the prototype, C L is the geometric scale ratio, C t is the plate thickness scale ratio, σ Y-s is the yield strength of the scaled model, σ Y-p is the yield strength of the prototype, E p is the elastic modulus of the prototype, E s is the elastic modulus of the scaled model.

[0021] Furthermore, an optimization method is also proposed. The parameters of the scaled model in step S3 include: the plate grid length of the scaled model, the molded breadth of the scaled model, the plate grid width of the scaled model, the attached plate thickness of the scaled model, the web height of the stiffener in the scaled model, the web thickness of the stiffener in the scaled model, the face plate width of the stiffener in the scaled model, and the face plate thickness of the stiffener in the scaled model.

[0022] Further, a preferred method is also proposed. The step S4 includes correcting the scaled model through a correction factor M stiff which is:

[0023]

[0024] Further, a preferred method is also proposed. The step S5 of obtaining the similarity difference range of different cross-section characteristics includes: the similarity difference range of the neutral axis height, the similarity difference range of the moment of inertia, and the similarity difference range of the section modulus after changing the rib direction.

[0025] Further, a preferred method is also proposed. The step S7 includes: when the similarity difference of the sagging condition is large, strengthening the deck and weakening the bottom plate; when the similarity difference of the hogging condition is large, weakening the deck and strengthening the bottom plate.

[0026] Based on the same inventive concept, the present invention also proposes a general scaled model design system for a hull girder considering the ultimate bending bearing capacity and buckling failure mode. The system includes:

[0027] A similarity criterion construction unit for constructing the similarity criterion of the bending load of the hull girder;

[0028] A stiffener number acquisition unit for adjusting the number of stiffeners to achieve local flexibility similarity and obtaining the number of stiffeners in the scaled model;

[0029] A parameter acquisition unit for determining the parameters of the scaled model;

[0030] A correction unit for achieving the similarity of the beam-column flexibility coefficient by correcting the length of the panel in the scaled model or the distance between two adjacent transverse stiffeners;

[0031] A recombination unit for recombining the layout directions of the ribs on the bottom plate and the deck to obtain the similarity difference range of different cross-section characteristics;

[0032] A reference model acquisition unit for selecting the model with the best similarity effect of the ultimate bearing capacity as the reference model;

[0033] A balancing unit for balancing the strength of the deck and the bottom plate based on the similarity difference of the sagging ultimate bearing capacity and the similarity difference of the hogging ultimate bearing capacity of the reference model;

[0034] An adjustment unit for adjusting the thickness of the similar plate or stiffener to simultaneously satisfy the similarity difference of the neutral axis height and the moment of inertia and complete the design of the scaled model.

[0035] Based on the same inventive concept, the present invention also provides a computer device, including a memory and a processor. A computer program is stored in the memory. When the processor runs the computer program stored in the memory, the processor executes a hull girder general scaling model design method considering ultimate bending load-carrying capacity and buckling failure mode as described in any one of the above.

[0036] Based on the same inventive concept, the present invention also provides a computer-readable storage medium. A computer program is stored on the computer-readable storage medium. When the computer program is run by a processor, it executes the steps of a hull girder general scaling model design method considering ultimate bending load-carrying capacity and buckling failure mode as described in any one of the above.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] A hull girder general scaling model design method considering ultimate bending load-carrying capacity and buckling failure mode proposed by the present invention, by considering the ultimate bending load-carrying capacity and buckling failure mode, avoids the simple distortion model that only relies on the scale ratio design in the existing method, and can more accurately reflect the true failure characteristics of the hull girder in the ultimate state. This is beneficial for better simulating and predicting the failure behavior of the structure when conducting hull structure design and safety assessment. During the design process of this method, through a series of meticulous steps, the similarity of the neutral axis height, moment of inertia, and section modulus can be relatively perfectly achieved. By optimizing these parameters, the behavior of the scaled model can be ensured to be similar to that of the prototype hull girder, thereby obtaining more reliable test results.

[0039] By adjusting the number and structural layout of the stiffeners, the present invention effectively ensures the similarity between the scaled model and the prototype in terms of local flexibility and strength. This makes the response of the hull girder under the stress state closer to the actual situation, thereby improving the design accuracy.

[0040] When selecting the reference model, the present invention considers the similarity difference in ultimate load-carrying capacity and balances the strength of the deck and bottom plate. This process can help optimize the structure of the hull girder and ensure that it can maintain a high load-carrying capacity under various ultimate conditions.

[0041] The hull girder general scaling model design method proposed by the present invention has strong versatility and can adapt to the design requirements of different hull girders. The same distortion model can simultaneously achieve the similarity of the ultimate load-carrying capacity in the sagging condition and the similarity of the ultimate load-carrying capacity in the hogging condition, and the error can be controlled within 5% at the same time. Meanwhile, according to the method proposed by the present invention, the similarity of the buckling failure mode can be achieved.

[0042] The present invention is mainly used in the ship field. Description of the Drawings

[0043] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0044] Figure 1 It is a flowchart of a general scaling model design method for a hull girder considering the ultimate bending capacity and buckling failure mode as described in Embodiment 1.

[0045] Figure 2 It is a schematic diagram of the double-bottom prototype section as described in Embodiment 11.

[0046] Figure 3 It is a preliminary design flowchart as described in Embodiment 11.

[0047] Figure 4 It is a schematic diagram of the distorsion model section as described in Embodiment 11.

[0048] Figure 5 It is a schematic diagram of the change in the distorsion model section as described in Embodiment 11.

[0049] Figure 6 It is a schematic diagram of the section of a certain Suez-class cruise ship as described in Embodiment 11.

[0050] Figure 7 It is a simplified schematic diagram of the section of a certain Suez-class cruise ship as described in Embodiment 11.

[0051] Figure 8 It is a schematic diagram of the distorsion model as described in Embodiment 11, where Figure 7 (a) is the uncorrected distorsion model, Figure 7 (b) is the distorsion model with the plate thickness changed, Figure 7 (c) is the distorsion model with the stiffener thickness changed;

[0052] Figure 9 It is a schematic diagram of the similarity verification of the ultimate bearing capacity as described in Embodiment 11, where Figure 9 (a) is the schematic diagram of the similarity verification of the hogging ultimate bearing capacity, Figure 9 (b) is the schematic diagram of the similarity verification of the sagging ultimate bearing capacity

[0053] Figure 10 It is a schematic diagram of the similarity verification of the failure mode as described in Embodiment 11, where Figure 10 (a) is the prototype, Figure 10 (b) is the schematic diagram of the uncorrected distorsion model, Figure 10 (c) is the schematic diagram of the distorsion model with the plate thickness changed, Figure 10 (d) is the schematic diagram of the distorsion model with the stiffener thickness changed. Specific implementation manner

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention may be combined with each other. The described embodiments are only some of the embodiments of the present invention, rather than all of the embodiments.

[0055] Embodiment 1. Refer to Figure 1 This embodiment is described. A general scaling model design method for a hull girder considering the ultimate bending capacity and buckling failure mode, the method includes:

[0056] Step S1: Construct a similarity criterion for the bending load of the hull girder;

[0057] Step S2: Adjust the number of stiffeners to achieve similarity of the flexibility coefficient of the local plate, and obtain the number of stiffeners in the scaled model;

[0058] Step S3: Determine the parameters of the scaled model;

[0059] Step S4: Achieve similarity of the beam-column flexibility coefficient by correcting the length of the panel in the scaled model or the spacing between two adjacent transverse stiffeners;

[0060] Step S5: Recombine the layout directions of the ribs on the bottom plate and the deck to obtain the similarity difference range of different cross-sectional characteristics;

[0061] Step S6: Select the model with the best similarity effect of the ultimate bearing capacity as the reference model;

[0062] Step S7: Balance the strength of the deck and the bottom plate based on the similarity differences of the sagging ultimate bearing capacity and the hogging ultimate bearing capacity of the reference model;

[0063] Step S8: Adjust the thickness of the similar plate or stiffener to simultaneously meet the similarity differences of the neutral axis height and the moment of inertia, and complete the design of the scaled model.

[0064] A general scaling model design method for hull girder considering ultimate bending capacity and buckling failure mode proposed in this embodiment, by considering the ultimate bending capacity and buckling failure mode, avoids the simple distortion model that only relies on the scaling ratio in the existing methods, and can more accurately reflect the true failure characteristics of the hull girder in the ultimate state. This is beneficial for better simulating and predicting the failure behavior of the structure when conducting hull structure design and safety assessment. During the design process of this method, through a series of meticulous steps, the similarity of the neutral axis height, the similarity of the moment of inertia, and the similarity of the section modulus can be relatively perfectly achieved. By optimizing these parameters, it can be ensured that the behavior of the scaled model is similar to that of the prototype hull girder, thus obtaining more reliable test results.

[0065] By adjusting the number and structural layout of stiffeners, the present invention effectively ensures the similarity between the scaled model and the prototype in terms of local flexibility and strength. This makes the response of the hull girder under the stress state closer to the actual situation, thereby improving the design accuracy.

[0066] Furthermore, when selecting the reference model, the similarity difference in ultimate load-carrying capacity is considered to balance the strength of the deck and the bottom plate. This process can help optimize the structure of the hull girder to ensure that it can maintain a high load-carrying capacity under various ultimate conditions.

[0067] The general scaling model design method for hull girder proposed in this embodiment has strong versatility and can adapt to the design requirements of different hull girders. The same distortion model can simultaneously achieve the similarity of the ultimate load-carrying capacity in the sagging condition and the similarity of the ultimate load-carrying capacity in the hogging condition, and the error can be controlled within 5% at the same time. Meanwhile, according to the method proposed in the present invention, the similarity of the buckling failure mode can be achieved.

[0068] Embodiment 2: This embodiment further limits a general scaling model design method for hull girder considering ultimate bending capacity and buckling failure mode described in Embodiment 1. The step S1 includes: local stiffened plate structure strength similarity criterion and hull girder structure strength similarity criterion.

[0069] Embodiment 3: This embodiment further limits a general scaling model design method for hull girder considering ultimate bending capacity and buckling failure mode described in Embodiment 1. The number of stiffeners in the scaled model in the step S2 includes:

[0070]

[0071] Wherein, N s is the number of stiffeners in the scaled model, N p is the number of stiffeners in the prototype, C L is the scaling ratio of geometric dimensions, C tis the scale ratio of the plate thickness, σ Y-s is the yield strength of the scaled model, σ Y-p is the yield strength of the prototype, E p is the elastic modulus of the prototype, E s is the elastic modulus of the scaled model.

[0072] Embodiment 4: This embodiment further limits a general scaled model design method for a hull girder considering the ultimate bending capacity and buckling failure mode described in Embodiment 1. The scaled model parameters in step S3 include: the grillage length of the scaled model, the molded breadth of the scaled model, the grillage width of the scaled model, the plating thickness of the scaled model, the web height of the stiffener in the scaled model, the web thickness of the stiffener in the scaled model, the face plate width of the stiffener in the scaled model, and the face plate thickness of the stiffener in the scaled model.

[0073] By precisely setting different geometric parameters, the strength and stiffness characteristics of the model can be adjusted more finely. For example, the web height, thickness, face plate width, and thickness of the stiffener in the scaled model will directly affect the buckling failure mode and load-bearing capacity of the model. By reasonably optimizing these parameters, it can be ensured that the ultimate load-bearing capacity and buckling failure mode of the scaled model better exhibit characteristics consistent with the prototype in the experiment.

[0074] In traditional scaled model design methods, errors often occur due to simplified design or neglect of details. This embodiment reduces the error between the model and the prototype by further refining various design parameters. For example, the fine adjustment of the grillage length, molded breadth, and each dimension of the stiffener can better maintain the consistency of local flexibility and global strength, thereby improving the reliability and prediction accuracy of the scaled model in actual tests.

[0075] Embodiment 5: This embodiment further limits a general scaled model design method for a hull girder considering the ultimate bending capacity and buckling failure mode described in Embodiment 3. Step S4 includes correcting the scaled model through a correction factor, and the correction factor M stiff is:

[0076]

[0077] Embodiment 6: This embodiment further limits a general scaled model design method for a hull girder considering the ultimate bending capacity and buckling failure mode described in Embodiment 1. The range of similarity differences in obtaining different cross-sectional characteristics in step S5 includes: the range of similarity differences in the neutral axis height after changing the stiffener direction, the range of similarity differences in the moment of inertia, and the range of similarity differences in the section modulus.

[0078] In the design of the scaled model of the hull girder, considering the similarity difference ranges of key parameters such as the neutral axis height, moment of inertia, and section modulus helps to optimize the design for a specific beam section. By adjusting these parameters, the performance of the actual structure under different loading conditions can be effectively simulated, avoiding the complex responses of the structure in bending and buckling failure modes being ignored due to simple scaling. Therefore, this embodiment can optimize the design to ensure the load-carrying capacity and stability of the hull girder under different working conditions.

[0079] In the practical application of the hull girder, different characteristics of the cross-section will significantly affect the load-carrying capacity and stability of the structure. By refining the similarity difference range, this embodiment takes into account these complex engineering factors and can better adapt to the design requirements of different types of hull girders. Therefore, the designed scaled model not only has high scientificity and theoretical basis but also strong engineering practicability.

[0080] Embodiment 7: This embodiment further defines a general scaled model design method for a hull girder considering the ultimate bending load-carrying capacity and buckling failure mode described in Embodiment 1. The step S7 includes: when the similarity difference in the sagging condition is large, strengthening the deck and weakening the bottom plate; when the similarity difference in the hogging condition is large, weakening the deck and strengthening the bottom plate.

[0081] The sagging condition is usually closely related to the longitudinal bending, load distribution, and flexural performance of the hull. When the deck bears vertical loads, it usually bears relatively large bending stresses, while the bending stresses of the bottom plate are relatively small. By strengthening the deck and weakening the bottom plate, the key role played by the deck during the loading process in the actual situation can be better simulated, improving the similarity of the test model and ensuring a good prediction of the actual performance of the hull by the test results.

[0082] For the case where the similarity difference in the hogging condition is relatively large, weaken the deck and strengthen the bottom plate: The hogging condition is a deformation mode of the hull under the action of waves or lateral loads, and the bottom plate will bear relatively large bending and buckling stresses. Through the design of weakening the deck and strengthening the bottom plate, the test model can be made closer to the mechanical behavior of the actual hull when simulating the hogging condition, thereby improving the adaptability and accuracy of the model.

[0083] In the design of the hull girder, the ultimate bending load-carrying capacity and buckling failure mode are key factors affecting the overall performance of the hull. Through this limitation, the design method can more effectively identify and strengthen key components, enhancing the stability of the overall structure, especially when facing the performance of the hull under extreme conditions. Through targeted strengthening or weakening design, the response of the actual hull under complex working conditions can be better simulated.

[0084] Embodiment 8. A general hull girder reduced scale model design system considering ultimate bending load-carrying capacity and buckling failure mode described in this embodiment, the system includes:

[0085] A similarity criterion construction unit for constructing similarity criteria for the bending load of the hull girder;

[0086] A stiffener number acquisition unit for adjusting the number of stiffeners to achieve similarity of local flexibility and obtaining the number of stiffeners in the reduced scale model;

[0087] A parameter acquisition unit for determining the parameters of the reduced scale model;

[0088] A correction unit for achieving similarity of beam-column flexibility coefficients by correcting the length of the panel in the reduced scale model or the distance between two adjacent transverse stiffeners;

[0089] A recombination unit for recombining the layout directions of the ribs on the bottom plate and the deck to obtain the similarity difference range of different cross-sectional properties;

[0090] A reference model acquisition unit for selecting the model with the best similarity effect of ultimate load-carrying capacity as the reference model;

[0091] A balancing unit for balancing the strength of the deck and the bottom plate based on the similarity differences of the midship ultimate load-carrying capacity and the hogging ultimate load-carrying capacity of the reference model;

[0092] An adjustment unit for adjusting the thickness of the similar plate or stiffener to simultaneously meet the similarity differences of the neutral axis height and the moment of inertia, and complete the design of the reduced scale model.

[0093] Embodiment 9. A computer device described in this embodiment includes a memory and a processor. A computer program is stored in the memory. When the processor runs the computer program stored in the memory, the processor executes a general hull girder reduced scale model design method described in any one of Embodiments 1 to 7 considering ultimate bending load-carrying capacity and buckling failure mode.

[0094] Embodiment 10. A computer-readable storage medium described in this embodiment has a computer program stored thereon. When the computer program is run by a processor, it executes the steps of a general hull girder reduced scale model design method described in any one of Embodiments 1 to 7 considering ultimate bending load-carrying capacity and buckling failure mode.

[0095] Embodiment 11. Refer to Figures 2 to 10Describe this embodiment. This embodiment provides a specific example for a general scaled model design method of a hull girder considering the ultimate bending capacity and buckling failure mode described in Embodiment 1, and is also used to explain Embodiments 2 to 7. Specifically:

[0096] Taking a double-bottom box girder as an example, a general scaled model design method of a hull girder considering the ultimate bending capacity and buckling failure mode proposed by the present invention is described and verified. The profile schematic diagram of the prototype is as shown in Figure 2 . The corresponding geometric and material parameters are shown in Table 1. For the convenience of representing the parameters of the prototype and the scaled model, the subscript p represents the prototype parameters ( p ), and the subscript s represents the scaled model parameters ( s ). Taking C L to represent the scale ratio of the geometric dimension, and taking C t to represent the scale ratio of the plate thickness.

[0097] Table 1 Prototype geometric and material parameters

[0098]

[0099] First, establish the similarity criteria for the bending load of the hull girder, including:

[0100] Strength similarity criterion for the local stiffened plate structure: The flexibility coefficient of the plate is similar (β s = β p ), and the beam-column flexibility coefficient of the stiffener is similar (λ s = λ p ).

[0101] Strength similarity criterion for the hull girder structure: The moment of inertia of the cross-section is similar (I s = I p C L 3 C t ), where I p is the moment of inertia of the cross-section of the prototype, and I s is the moment of inertia of the cross-section of the scaled model), the neutral axis of the cross-section is similar (Z s = Z p C L ), where Z p is the height of the neutral axis of the prototype, and Z s is the height of the neutral axis of the scaled model), and the section modulus is similar (W s = W p C L 2 C t ), where W p is the section modulus of the prototype, and W s is the section modulus of the scaled model).

[0102] Furthermore, this embodiment also proposes a preliminary design method for a hull girder. After the material properties and dimensional parameters of the prototype are known, the preliminary design flow chart is as shown in Figure 3 the following. The specific steps include:

[0103] Step 1: Achieve similarity in the flexibility coefficient (β) of the local panel by changing the number of stiffeners, and thus derive the calculation formula for the number of stiffeners N in the scaled model s , where the number of stiffeners N in the scaled model s ):

[0104]

[0105] Step 2: Preliminary determine the parameters of the scaled model. Among them, the panel length (L s or a) of the scaled model: L s = L p C L ,;

[0106] The molded breadth (B s ) of the scaled model: B s = B p C L ;

[0107] The panel width (b s ) of the scaled model: b s = B s ÷ (N s + 1);

[0108] The thickness of the attached plate (t p-s ) of the scaled model: t p-s = t p-p C t , t p-p is the thickness of the attached plate of the prototype;

[0109] In order to maintain a similar buckling failure mode between the scaled model and the prototype, this embodiment proposes that: the web height (h w-s ) of the stiffener in the scaled model: h w-s = h w-p C t M stiff , h w-p is the web height of the prototype, the web thickness (t w-s ) of the stiffener in the scaled model: t w-s = t w-p C t M stiff , t w-p is the web thickness of the prototype, the panel width (b f-s ) of the stiffener in the scaled model: b f-s = bf-p C t M stiff and b f-p is the panel width of the prototype. The panel thickness (t f-s ) of the stiffener in the scaled model: t f-s = t f-p C t M stiff and t f-p is the panel thickness of the prototype. It should be noted that the geometric and plate thickness scale ratios of the stiffener both adopt the plate thickness scale ratio, i.e., Ct. At the same time, the calculation of each parameter introduces M stiff as a correction factor, and the calculation formula of the correction factor is:

[0110] Step 3: Achieve the similarity of the beam-column flexibility coefficient by modifying the length of the plate grid or the distance a or L between two adjacent transverse stiffeners in the scaled model s in the scaled model.

[0111] Taking the geometric scale ratio C L = 0.125, C t = 0.375 as an example, the cross-section of the formed distortion model is as Figure 4 shown.

[0112] However, after the above preliminary design is completed, the cross-section properties such as the neutral axis height, moment of inertia, and section modulus of the scaled model cannot meet the similarity requirements. Therefore, this embodiment proposes a distortion model design method that can simultaneously meet the similarity criterion requirements of the local stiffened plate and the hull girder.

[0113] First, clarify the reasons why such a distortion model cannot meet the similarity criterion, including:

[0114] First, under a specific combination of scale ratios, there is a situation in the local area of the distortion model where the stiffened plate in the prototype is scaled to a plate, that is, the local structural form changes from a stiffened plate to a plate, which will cause the similarity of the local area area not to be met. And area is one of the important factors affecting the cross-section moment of inertia. Therefore, after this design situation occurs, the similarity of the cross-section properties will definitely be destroyed.

[0115] Second, for the dimension design of the stiffener in the distortion model, in the initial design of this embodiment, to maintain the similarity of the buckling failure mode, it is proposed to scale the web height, web thickness, panel width, and panel thickness with the plate thickness scale ratio. Therefore, the stiffener in the distortion model is strengthened compared with the stiffener in the fully similar model, resulting in the shortening of the distance between the stiffener in the distortion model and the neutral axis, and finally affecting the similarity of the cross-section properties.

[0116] Thirdly, since the scale-down design of the geometric dimensions of the stiffeners uses the scale ratio of the plate thickness, the dimensions of the stiffeners become larger compared to the full-scale similarity model. Due to the limited dimensional space in the double-bottom area, the direction of the stiffeners needs to be changed, causing the stiffeners on the inner bottom plate to change from the direction away from the centroid in the full-scale similarity or prototype to the direction close to the centroid, which affects the similarity of the cross-sectional properties.

[0117] The reasons for the differences in the similarity of the cross-sectional properties of the distorted models caused by the initial design are the above three points. In this embodiment, the complete similarity of the cross-sectional properties is achieved through the following steps, including:

[0118] Taking the initial design as the first step, on this basis, in the second step, re-combine the layout directions of the ribs on the bottom plate and the deck to obtain the range of similarity differences in various cross-sectional properties, including: the range of similarity differences in the neutral axis height, the range of similarity differences in the moment of inertia, and the range of similarity differences in the section modulus after changing the rib direction.

[0119] In the third step, select the model with the best similarity effect of the ultimate bearing capacity of the model as the reference model from the four models with the smallest similarity difference in the moment of inertia, the largest similarity difference in the moment of inertia, the smallest similarity difference in the neutral axis, and the largest similarity difference in the neutral axis.

[0120] In the fourth step, based on the similarity differences in the ultimate bearing capacity of sagging and hogging of the reference model, balance the strength of the deck and the bottom plate, that is: if the similarity difference in the sagging condition is large, the deck needs to be strengthened and the bottom plate needs to be weakened, while if the similarity difference in the hogging condition is large, the deck needs to be weakened and the bottom plate needs to be strengthened.

[0121] In the fifth step, achieve the similarity differences in the neutral axis height and the moment of inertia simultaneously by changing the thickness of the similar plates or stiffeners.

[0122] In the sixth step, complete the scale-down model design, and the cross-sectional form changes generated in each step are as Figure 5 shown.

[0123] Taking a certain Suezmax oil tanker as an example, illustrate the scale-down design process proposed in this embodiment and give the verification effect. The cross-section of this Suezmax oil tanker refers to International Ship and Offshore Structures Congress (ISSC, 2012), as Figure 6 shown. For the convenience of explaining the scale-down process, the simplified cross-section of this cross-section is as Figure 7 shown. The geometric dimension scale ratio (C L ) is taken as 0.1, and the plate thickness scale ratio (C t ) is taken as 0.3.

[0124] According to the method proposed by the present invention, the dimensional parameters of the prototype and the scaled model are shown in Table 2. The geometric section of the scaled model is as Figure 8 shown.

[0125] Table 2 Simplified section parameters of a Suez-class cruise ship

[0126]

[0127] Figure 9 For the similarity verification of the ultimate bearing capacity, it can be seen that the corrected distorted model is closest to the prototype, with an error of less than 3%. Figure 10 For the similarity verification of the failure mode, the compressed areas all show the buckling of the plate grid and the lateral buckling of the ribs, and the failure modes are the same.

[0128] The specific embodiments of the present invention disclosed above are only used to help explain the present invention. The specific embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. According to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention.

Claims

1. A method for designing a universal scaled model of a hull girder considering the ultimate bending bearing capacity and buckling failure mode, characterized in that: The method comprises: Step S1: constructing a similarity criterion for hull girder bending load; Step S2: adjusting the number of stiffeners to achieve similar flexibility coefficients of local plates, and obtaining the number of stiffeners in the scaled model; Step S3: Determine the scale model parameters; Step S4: achieving similarity of beam-column flexibility coefficients by correcting the length of the plate grid or the distance between two adjacent transverse stiffeners in the scaled model; Step S5: recombining the arrangement directions of the reinforcements on the bottom plate and the deck to obtain the similarity difference range of different cross-sectional characteristics; Step S6: Selecting the model with the best ultimate bearing capacity similarity effect as the benchmark model; Step S7: balancing the strength of the deck and the bottom plate based on the similarity difference of the ultimate bearing capacity of the sag and the ultimate bearing capacity of the hooping of the benchmark model; Step S8: Adjust the thickness of the side plate or the stiffener to simultaneously meet the similarity difference of the neutral axis height and the moment of inertia, and complete the design of the scaled model.

2. A method for designing a universal scaled model of a hull beam considering the ultimate bending bearing capacity and buckling failure mode according to claim 1, characterized in that: The step S1 includes: a local stiffened plate structural strength similarity criterion and a hull beam structural strength similarity criterion.

3. A method for designing a universal scaled model of a hull beam considering the ultimate bending bearing capacity and buckling failure mode according to claim 1, characterized in that: The number of reinforcing ribs in the scaled model in step S2 includes: Among them, N s is the number of stiffeners in the scaled model, N p is the number of reinforcing ribs in the prototype, C L is the scale ratio of geometric dimensions, C t is the reduction ratio of plate thickness, σ Y-s is the yield strength of the scaled model, σ Y-p is the yield strength of the prototype, E p is the elastic modulus of the prototype, E s is the elastic modulus of the scaled model.

4. A method for designing a universal scaled model of a hull girder considering the ultimate bending bearing capacity and buckling failure mode according to claim 1, characterized in that: The scaled model parameters in step S3 include: the panel length of the scaled model, the profile width of the scaled model, the panel width of the scaled model, the strip thickness of the scaled model, the web height of the stiffener in the scaled model, the web thickness of the stiffener in the scaled model, the panel width of the stiffener in the scaled model, and the panel thickness of the stiffener in the scaled model.

5. A method for designing a universal scaled model of a hull beam considering the ultimate bending bearing capacity and buckling failure mode according to claim 3, characterized in that: The step S4 includes correcting the scale model by using a correction factor, wherein the correction factor M stiff for:

6. A method for designing a universal scaled model of a hull girder considering ultimate bending bearing capacity and buckling failure mode according to claim 1, characterized in that: The step S5 obtains the similarity difference ranges of different cross-sectional characteristics, including: the similarity difference range of the neutral axis height after changing the rib direction, the similarity difference range of the moment of inertia, and the similarity difference range of the section modulus.

7. A method for designing a universal scaled model of a hull girder considering ultimate bending bearing capacity and buckling failure mode according to claim 1, characterized in that: The step S7 includes: when the similarity difference of the sagging working condition is large, strengthening the deck and weakening the bottom plate; when the similarity difference of the hoisting working condition is large, weakening the deck and strengthening the bottom plate.

8. A universal scaled model design system for hull beams considering ultimate bending bearing capacity and buckling failure mode, characterized in that: The system comprises: A similarity criterion construction unit is used to construct similarity criterion for hull girder bending load; A rib number acquisition unit is used to adjust the number of ribs to achieve local flexibility similarity and to obtain the number of ribs in the scaled model; A parameter acquisition unit, used to determine the scaled model parameters; Correction unit, used to achieve similarity of beam-column flexibility coefficients by correcting the length of the plate grid or the distance between two adjacent transverse stiffeners in the scaled model; The reorganization unit is used to reorganize the arrangement direction of the reinforcement on the bottom plate and deck to obtain the similarity difference range of different cross-sectional properties; A benchmark model acquisition unit, used for selecting a model with the best ultimate bearing capacity similarity effect as a benchmark model; A balancing unit is used to balance the strength of the deck and the bottom plate based on the similar difference of the ultimate bearing capacity of the mid-sag and the similar difference of the ultimate bearing capacity of the mid-hogging of the benchmark model; The adjustment unit is used to adjust the thickness of similar plates or stiffeners to simultaneously meet the similarity differences in neutral axis height and moment of inertia, thus completing the design of the scaled model.

9. A computer device, characterized in that: The invention comprises a memory and a processor, wherein a computer program is stored in the memory, and when the processor runs the computer program stored in the memory, the processor executes a general scaled model design method for a hull beam considering the ultimate bending bearing capacity and the buckling failure mode according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, which, when executed by a processor, executes the steps of a method for designing a universal scaled model of a hull beam considering ultimate bending bearing capacity and buckling failure mode as claimed in any one of claims 1 to 7.

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