Die shrinkage method for ship and bridge collision experiment

Abstract

The invention discloses a model shrinking method for a ship and bridge collision experiment. The method comprises the following steps: simplifying a ship and bridge collision model; establishing a ship-bridge collision dynamics similarity model; based on the established mechanical similarity model, carrying out ship and bridge collision model shrinkage verification; on the basis of a model shrinkage verification result, performing model shrinkage model optimization iteration; and an optimized shrinkage model is obtained. The invention provides a systematic model shrinkage design method based on geometric similarity, material invariance and dynamic similarity principles. According to the method, a system verification system of an energy consumption path, a force-displacement curve and a failure mode is constructed, and the consistency of a mold shrinkage result and a full-size prototype in multiple dimensions is ensured. According to the optimization iteration design method of the shrinkage model, accurate reduction of complex plastic deformation and energy dissipation characteristics of the ship bow in collision can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of ship-bridge collision, and in particular relates to a shrinking method for a ship-bridge collision experiment. Background Art

[0002] In the field of ship-bridge collision research, the main research methods at this stage include numerical simulation analysis and physical collision experiments.

[0003] Numerical simulation technology is widely used in ship-bridge collision research due to its efficiency and flexibility. However, its simulation accuracy is limited by model assumptions and parameter settings. Especially under the local response of complex structures or the coupling of multiple factors, it is difficult to fully reflect the actual collision behavior.

[0004] Traditional full-scale physical collision experiments can directly reveal the mechanical behavior of collisions, but their high cost, large test site requirements, and difficulty in implementation limit their practical application. In contrast, scaled-down experiments offer a viable alternative due to their low cost, high repeatability, and direct physical phenomena. They employ the principles of geometric and mechanical similarity to achieve a reasonable approximation of full-scale collision behavior.

[0005] There are currently some related patents for ship-bridge collision scenarios, but some problems still exist:

[0006] Chinese Patent 202410918052.0, a design method for subway head car collision reduction molds that meets gravity criteria and pose equivalence, proposes a subway reduction mold design method based on static parameter and dynamic response optimization. This method constructs an equivalent reduction mold model with high pose similarity through geometric size adjustment, material correction, and parameter optimization. It effectively restores the dynamic pose changes of the prototype in train collision experiments and improves the accuracy of the model in static and dynamic response through optimization algorithms. However, the above method still has the following deficiencies in reduction mold technology, or there are significant differences with this patent:

[0007] First, it's difficult to simulate plastic deformation during a collision: The method focuses on pose similarity and overall matching of dynamic responses, but doesn't consider the stress characteristics of the vehicle body during a collision. This suggests that the previous patent focuses more on multibody dynamics, while this patent focuses on the plasticity of the structure.

[0008] Second, the scenarios they address differ: The previous patent focused on a specific collision scenario: the collision posture of a subway train in a subway collision. This patent, on the other hand, focuses on the specific plastic deformation patterns, collision force characteristics, and energy transfer characteristics of ships in ship-bridge collisions. This method is applicable only to the specific scenario of subway collisions and is difficult to directly generalize to ship-bridge collisions.

[0009] Chinese Patent 201811591809.0 discloses a method for constructing a train equivalent mold and a train equivalent mold. This method utilizes dynamic parameter scaling factors to achieve a reduced mold design for the train structure. Specifically, the locomotive head car is divided into a deformation energy absorption zone and a non-deformation zone, and a honeycomb aluminum cylinder is introduced as the primary energy dissipation structure. This method demonstrates good dynamic response reduction in train collisions, but compared to the patent's application requirements in ship-bridge collisions, it has the following differences and shortcomings:

[0010] First, application scenarios: This patent targets train collision scenarios, focusing on the overall dynamic response of the train during a collision and the energy absorption characteristics of the deformation zone. In ship-bridge collision scenarios, however, the interaction between the bow and the bridge piers exhibits significant localized damage, resulting in more complex collision force peaks, deformation patterns in the contact area, and energy dissipation paths, making it difficult to directly equate these using train collision reduction methods.

[0011] Second, there is a lack of a verification system: Although the patent uses a dynamic parameter proportional factor to perform a mold reduction design, it does not provide a method to verify the consistency between the mold reduction results and the full-size prototype. In particular, there is a lack of systematic verification of key indicators such as the force-displacement curve, energy consumption path, and failure mode, making it difficult to evaluate the accuracy of the mold reduction method.

[0012] Chinese Patent 201710591020.4, a test device for simulating ship-bridge collisions, constructs a scaled model of an actual ship bow, a target bridge pier, and related supporting equipment, enabling a relatively realistic simulation of the dynamic process of a ship-bridge collision in an experiment. Its innovation lies in fully considering the impact of the upper and lower structures of the piers and the boundary conditions of the surrounding piers on the damage form of the target piers. At the same time, the use of an axial force compensation component solves the problem of insufficient axial force caused by the inability to scale gravity acceleration in the scaled model. However, this patent fails to address the core issues of ship-bridge collision reduction, and has the following deficiencies or differences in the reduction principles and methods:

[0013] First, a systematic mold reduction method was not proposed: A mold reduction methodology based on the principles of geometric similarity, dynamic similarity, and material invariance was not clearly proposed, and the theoretical framework and technical basis for mold reduction were not clear. Model design was largely based on experience and lacked the support of a systematic mold reduction solution.

[0014] Second, there is a lack of a verification system: there is a lack of a consistency verification system for experimental results after model reduction. The device focuses on the physical experiment itself, and does not provide a verification method between the scaled model and the full-scale model, especially in terms of consistency verification of key indicators such as energy consumption path, force-displacement curve and bow failure mode.

[0015] Third, different emphasis: This patent focuses more on the construction and implementation of physical test equipment, and does not conduct in-depth research on the dynamic response and energy dissipation laws of the bow structure during the collision. Summary of the Invention

[0016] Aiming at the problems existing in existing ship-bridge collision research, such as unsystematic shrinkage method, inaccurate energy consumption path simulation, unreasonable simplification of key structures and lack of verification system, the present invention proposes a shrinkage method for ship-bridge collision experiment.

[0017] The technical solution of the present invention is: a shrinking method for a ship-bridge collision test, comprising the following steps:

[0018] A. Simplify the ship-bridge collision model;

[0019] B. Establish a ship-bridge collision dynamics similarity model;

[0020] C. Based on the established mechanical similarity model, conduct ship-bridge collision scale model verification;

[0021] D. Based on the mold reduction verification results, perform mold reduction model optimization iteration;

[0022] E. Get the optimized shrink mold model.

[0023] Furthermore, step A simplifies the ship-bridge collision model. The specific process is as follows:

[0024] a1. Simplify the key structures of ships and bridge piers;

[0025] a2. During the simplification process of the bridge pier, the geometric shape and stiffness characteristics of the key load-bearing parts should be retained;

[0026] a3. During the simplification process, the bow section is retained and counterweights are added;

[0027] a4. The mechanical properties of the simplified ship model remain similar to those of the ship prototype.

[0028] Furthermore, the simplified ship-bridge collision model ensures that the mechanical response, stress propagation path and energy dissipation characteristics during the collision are consistent with the prototype model.

[0029] Furthermore, step B establishes a ship-bridge collision dynamics similarity model. The specific process is as follows:

[0030] b1. Construct a scaled-down framework for the ship-bridge collision dynamics model based on the similarity of unchanged materials;

[0031] b2. Based on the simplified model, establish geometric similarity with the reduced mold frame;

[0032] b3. Based on the simplified model, establish the dynamic similarity with the reduced mold frame;

[0033] b4. Based on the simplified model, establish kinematic similarity with the reduced mold frame.

[0034] Furthermore, step b2 establishes geometric similarity with the reduced mold frame based on the simplified model, as follows:

[0035] First, geometric similarity requires that the prototype and model remain strictly consistent in shape and proportion;

[0036] Then, geometric similarity ensures that the geometric features of the structure are not distorted.

[0037] Furthermore, step b3 is based on the simplified model and establishes the dynamic similarity with the reduced mold frame as follows:

[0038] First, dynamic similarity requires that the prototype and the model be consistent in mechanical properties and response relationships;

[0039] Then, dynamic similarity ensures that the inertial forces are consistent with the prototype.

[0040] Furthermore, step b4 is based on the simplified model to establish the kinematic similarity with the reduced mold frame, as follows:

[0041] First, kinematic similarity requires that the prototype and the model be consistent in motion trajectory, velocity distribution, and deformation pattern;

[0042] Then, kinematic similarity ensures that the motion processes of the prototype and the model remain similar in time scale.

[0043] Furthermore, in step C, based on the established mechanical similarity model, a bridge collision scale model verification is performed. The specific process is as follows:

[0044] First, after the scaled-down model is constructed, the consistency of the results between the scaled-down model and the prototype model is verified through simulation calculations, thereby evaluating the reliability and accuracy of the scaled-down model.

[0045] Then, analyze the energy consumption path, select specific verification indicators, and define the corresponding error range;

[0046] Then, analyze the force-displacement curve, select specific verification indicators, and define the corresponding error range;

[0047] Finally, analyze the failure mode, select specific verification indicators, and define the corresponding error range.

[0048] Furthermore, step D performs iterative optimization of the reduction mold model based on the reduction mold verification results. The specific process is as follows:

[0049] First, based on the similarity of unchanged materials, determine the model optimization object:

[0050] Then, the structure of the model optimization object is optimized.

[0051] The beneficial effects of the present invention are as follows:

[0052] The present invention solves the problems of the current unsystematic shrinking method, inaccurate energy consumption path simulation, unreasonable simplification of key structures and lack of verification system.

[0053] The present invention proposes a systematic shrinkage design method based on the principles of geometric similarity, material invariance and dynamic similarity.

[0054] The present invention constructs a systematic verification system for force-displacement curves, energy dissipation paths and failure modes, which can ensure the consistency of reduction mold results with full-size prototypes in multiple dimensions.

[0055] The present invention proposes an optimized iterative design method for a reduced mold model, which can accurately restore the complex plastic deformation and energy dissipation characteristics of a ship bow during a collision. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a flow chart of the method of the present invention;

[0057] Figure 2 1 is a simplified model diagram of a bow according to an embodiment of the present invention;

[0058] Figure 3 1 is a diagram showing stress transfer paths and failure modes before and after mold reduction according to an embodiment of the present invention;

[0059] Figure 4 1 is a force-displacement curve diagram before and after mold reduction according to an embodiment of the present invention;

[0060] in:

[0061] 1. Finite element mesh division of bow, 2. Bulkhead, 3. Hull, 4. Deck. DETAILED DESCRIPTION

[0062] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments:

[0063] like Figures 1 to 4 As shown, a reduction model method for a ship-bridge collision test includes the following steps:

[0064] A. Simplify the ship-bridge collision model;

[0065] B. Establish a ship-bridge collision dynamics similarity model;

[0066] C. Based on the established mechanical similarity model, conduct ship-bridge collision scale model verification;

[0067] D. Based on the mold reduction verification results, perform mold reduction model optimization iteration;

[0068] E. Get the optimized shrink mold model.

[0069] Step A simplifies the ship-bridge collision model. The specific process is as follows:

[0070] a1. Simplify the key structures of ships and bridge piers;

[0071] a2. During the simplification process of the bridge pier, the geometric shape and stiffness characteristics of the key load-bearing parts should be retained;

[0072] a3. During the simplification process, the bow section is retained and counterweights are added;

[0073] a4. The mechanical properties of the simplified ship model remain similar to those of the ship prototype.

[0074] The simplified ship-bridge collision model ensures that the mechanical response, stress propagation path and energy dissipation characteristics during the collision are consistent with the prototype model.

[0075] Step B: Establish the ship-bridge collision dynamics similarity model. The specific process is as follows:

[0076] b1. Construct a scaled-down framework for the ship-bridge collision dynamics model based on the similarity of unchanged materials;

[0077] b2. Based on the simplified model, establish geometric similarity with the reduced mold frame;

[0078] b3. Based on the simplified model, establish the dynamic similarity with the reduced mold frame;

[0079] b4. Based on the simplified model, establish kinematic similarity with the reduced mold frame.

[0080] Step b2 is to establish geometric similarity with the reduced mold frame based on the simplified model, as follows:

[0081] First, geometric similarity requires that the prototype and model remain strictly consistent in shape and proportion;

[0082] Then, geometric similarity ensures that the geometric features of the structure are not distorted.

[0083] Step b3 is based on the simplified model and establishes the dynamic similarity with the reduced mold frame, as follows:

[0084] First, dynamic similarity requires that the prototype and the model be consistent in mechanical properties and response relationships;

[0085] Then, dynamic similarity ensures that the inertial forces are consistent with the prototype.

[0086] Step b4 is based on the simplified model and establishes kinematic similarity with the reduced mold frame, as follows:

[0087] First, kinematic similarity requires that the prototype and the model be consistent in motion trajectory, velocity distribution, and deformation pattern;

[0088] Then, kinematic similarity ensures that the motion processes of the prototype and the model remain similar in time scale.

[0089] Step C: Based on the established mechanical similarity model, the bridge collision reduction model is verified. The specific process is as follows:

[0090] First, after the scaled-down model is constructed, the consistency of the results between the scaled-down model and the prototype model is verified through simulation calculations, thereby evaluating the reliability and accuracy of the scaled-down model.

[0091] Then, analyze the energy consumption path, select specific verification indicators, and define the corresponding error range;

[0092] Then, analyze the force-displacement curve, select specific verification indicators, and define the corresponding error range;

[0093] Finally, analyze the failure mode, select specific verification indicators, and define the corresponding error range.

[0094] Step D performs iterative optimization of the shrink mold model based on the shrink mold verification results. The specific process is as follows:

[0095] First, based on the similarity of unchanged materials, determine the model optimization object:

[0096] Then, the structure of the model optimization object is optimized.

[0097] Specifically, step A simplifies the ship-bridge collision model as follows:

[0098] First, the geometric shape and stiffness characteristics of the key load-bearing parts of the pier are retained during the simplification process;

[0099] Then, since the rear structure of the ship does not directly participate in the plastic deformation and energy dissipation during the collision, only the bow part is retained and counterweight is added;

[0100] Finally, by keeping the appearance consistent with the prototype ship and reasonably setting the internal structure, the mechanical performance is kept similar to that of the ship prototype.

[0101] More specifically, the internal structure includes a deck 4 and a bulkhead 2 ; the external structure includes an outer shell 3 .

[0102] The model is simplified by retaining the necessary structural features and stiffness distribution at key locations, such as Figure 2 As shown, it ensures that the mechanical response, stress propagation path and energy dissipation characteristics during the collision are consistent with the prototype.

[0103] Specifically, step B establishes a ship-bridge collision dynamics similarity model as follows:

[0104] Traditional similarity theory requires that material parameters before and after mold reduction change with the scale ratio. To improve the convenience of engineering applications, this invention adopts the similarity principle of unchanged materials to construct a reduced mold framework for the ship-bridge collision dynamics model.

[0105] The present invention ensures that the physical properties before and after mold reduction remain consistent through three aspects: geometric similarity, dynamic similarity, and kinematic similarity, thereby achieving model reduction while maintaining effective simulation accuracy and engineering application effects.

[0106] Correspondingly, step b2 is geometrically similar and is as follows:

[0107] b21. Similarity requires that the prototype and model remain strictly consistent in shape and proportion, but the size is scaled by the scale factor λ.

[0108] b22. The geometric parameters of the model are strictly reduced according to the scale ratio λ;

[0109] b221. For example, the linear dimensions of the original bow structure, such as length, width, and height, are all scaled by λ;

[0110] b222. For thickness parameters, such as the thickness of key parts such as decks, bulkheads, and stiffeners, scale them using the same scale ratio λ to ensure that the proportions of each part are consistent with the prototype;

[0111] b223. ​​The size and distribution of key feature areas, such as energy absorption areas, connection nodes, and support parts, should be scaled to maintain similarity to the prototype and ensure that the geometric features of the structure are not distorted;

[0112] b224. During the reduction process, the complex compartment layout, rib spacing, and local transition areas inside the bow are accurately modeled according to the scale ratio λ.

[0113] b23. Through geometric size scaling, a geometric basis is provided for subsequent dynamic and kinematic similarity analysis, while avoiding errors introduced due to improper processing of local features.

[0114] Accordingly, the kinetics of step b3 are similar, as follows:

[0115] b31. Dynamic similarity requires that the prototype and model be consistent in mechanical properties and response relationships;

[0116] b32. Under the premise that material parameters remain unchanged, dynamic similarity is mainly achieved by scaling parameters such as load, speed and time.

[0117] More specifically, the mass of a structure is proportional to its volume, and the scale factor λ 3 The collision speed must be the square root of the scale ratio Adjustments were made to ensure the inertial forces were consistent with the prototype.

[0118] More specifically, the key to keeping the stress and deformation of the structure similar under external loads lies in the reasonable adjustment of the load after mold reduction.

[0119] Correspondingly, the kinematics of step b4 are similar and are as follows:

[0120] b41. Kinematic similarity requires that the prototype and model be consistent in motion trajectory, velocity distribution, and deformation pattern;

[0121] b42. Under the premise that material parameters remain unchanged, kinematic similarity is achieved by scaling variables such as time and velocity.

[0122] More specifically, the model's motion time should be calculated as the square root of the scale factor λ Scaling was performed to ensure that the motion of the prototype and the model remained similar in time scale.

[0123] More specifically, the speed The displacement is scaled by λ to ensure the consistency of the motion state and deformation mode.

[0124] The overall similarity principle is shown in Table 1.

[0125] Table 1 Similarity principle

[0126]

[0127]

[0128] Specifically, step C is to conduct ship-bridge collision scale model verification based on the established mechanical similarity model, as follows:

[0129] Specifically, we analyze the energy consumption path, select specific verification indicators, and define the corresponding error range, as follows:

[0130] c11. The energy dissipation path is an important indicator that reflects the spatial distribution and transfer pattern of energy dissipation in a structure during a collision.

[0131] c12. The verification method is as follows:

[0132] c121. Extract stress cloud maps of key energy-consuming areas of the prototype and scaled-down model during the collision process. The key energy-consuming areas include the bow hull, energy absorption unit, and pier support area.

[0133] c122. Observe stress transfer paths and concentration areas.

[0134] c123. Compare the stress peaks and time series in key energy-consuming areas to ensure that the stress evolution at key locations and time points is consistent.

[0135] c13. Its verification indicators are as follows:

[0136] c131. Stress transfer path: The stress concentration area and propagation order of the reduction model are consistent with those of the prototype.

[0137] c132. Stress magnitude: The error between the peak stress and the average stress in the key energy consumption area is less than 5%.

[0138] Specifically, we analyze the force-displacement curve, select specific verification indicators, and define the corresponding error range, as follows:

[0139] c21. The force-displacement curve is a key indicator that reflects the relationship between force and deformation of a structure during a collision.

[0140] c22. The verification method is as follows:

[0141] c221. Extract the force-displacement curves of the scaled-down model and the prototype model during simulation and compare key characteristic points, including loading stiffness, peak force, and unloading stiffness.

[0142] c222. Compare the similarities in the curve morphology during loading and unloading.

[0143] c23. Its verification indicators are as follows:

[0144] c231. Peak force: The maximum impact force error between the reduction model and the prototype model is less than 5%.

[0145] c232.Average Force: The average force during the collision has an error of less than 5%.

[0146] c233. Impact history: The trend of the entire impact history curve is consistent.

[0147] Specifically, we analyze the failure mode, select specific verification indicators, and define the corresponding error range, as follows:

[0148] c31. Failure mode verification is used to analyze whether the scaled-down model and the prototype model experience consistent structural damage during a collision.

[0149] c32. The verification method is as follows:

[0150] Compare the failure modes of the bow model, including the outer plate crushing form, bulkhead buckling form, damage failure path, etc.

[0151] c33. Its verification indicators are as follows:

[0152] The deformation, damage and failure characteristics of the entire impact process are consistent.

[0153] Specifically, step D performs iterative optimization of the reduction mold model based on the reduction mold verification results, as follows:

[0154] The material invariance similarity principle assumes that all material properties (such as elastic modulus, yield strength, density, etc.) remain unchanged between the scaled model and the prototype model before and after the reduction. This theory ensures that the mechanical response of the scaled model is consistent with the full-scale prototype model by adjusting parameters such as geometric dimensions, speed, and time. The above method has limitations: the behavior of the material during yielding, rheology, or local failure may vary due to differences in scale and material microstructure, resulting in differences in the order of plastic deformation, failure mode, etc. Although the material invariance similarity principle ensures the similarity of stress in the elastic stage, in the actual plastic collision process, the collision force and failure mode of the model and prototype may not be completely consistent. In particular, the difference in response after the material yields may lead to different energy absorption mechanisms.

[0155] Therefore, after scaling according to this principle, the verification results often cannot fully meet the requirements, and the model needs to be debugged and optimized to make the mechanical response at the moment of collision closer to the prototype. The model optimization method is as follows:

[0156] Specifically, if the energy consumption path does not meet the requirements, the optimization method is as follows:

[0157] When the stress transfer process is not in compliance, local components such as partitions and ribs are added or removed from the reduction model according to the calculation results to adjust the local stiffness and guide the stress transfer.

[0158] When the local or overall stress values ​​are inconsistent, the structural thickness of the area can be appropriately adjusted to achieve optimized stiffness distribution.

[0159] Specifically, if the force-displacement curve does not meet the requirements, the optimization method is as follows:

[0160] This step should be carried out in conjunction with the "energy dissipation path non-compliance" step to determine the correspondence between key characteristic points such as the initial peak, maximum peak, and inflection point of the curve and the ship's plastic energy dissipation path. Based on the errors in the scaled-down model, the bulkhead ribs should be added or removed, the plate thickness should be adjusted, and the distributed stiffness should be optimized.

[0161] Specifically, if the failure mode does not meet the requirements, the optimization method is as follows:

[0162] For areas in the reduction model where the failure mode does not conform, the structural damage failure strain is readjusted.

[0163] According to the final optimization results of the 10000DWT ship model, Figure 3The stress transfer paths and failure modes before and after mold reduction were compared, showing the bow stress conditions at three typical characteristic moments: wedge bow contact, bulbous bow contact, and maximum impact depth. The results show that the stress transfer paths and stress distributions of the models before and after mold reduction are highly consistent, and the plastic failure modes of the bow are highly similar.

[0164] According to the final optimization results of the 10000DWT ship model, Figure 4 The force-displacement curves before and after mold reduction were compared. The results showed that the maximum impact force error between the mold reduction model and the prototype model was 4.2%, the average force error during the collision was 2.1%, and the trends of the full impact history curves were consistent.

[0165] The present invention solves the problems of the current unsystematic shrinking method, inaccurate energy consumption path simulation, unreasonable simplification of key structures and lack of verification system.

[0166] The present invention proposes a systematic shrinkage design method based on the principles of geometric similarity, material invariance and dynamic similarity.

[0167] The present invention constructs a systematic verification system for force-displacement curves, energy dissipation paths and failure modes, which can ensure the consistency of reduction mold results with full-size prototypes in multiple dimensions.

[0168] The present invention proposes an optimized iterative design method for a reduced mold model, which can accurately restore the complex plastic deformation and energy dissipation characteristics of a ship bow during a collision.

Claims

1. A reduction model method for a ship bridge collision test, characterized by: The following steps are involved: A. Simplify the ship-bridge collision model; B. Establish a ship-bridge collision dynamics similarity model; C. Based on the established mechanical similarity model, conduct ship-bridge collision scale model verification; D. Based on the mold reduction verification results, perform mold reduction model optimization iteration; E. Get the optimized shrink mold model.

2. The shrinking method for ship-bridge collision test according to claim 1, characterized in that: Step A simplifies the ship-bridge collision model. The specific process is as follows: a1. Simplify the key structures of ships and bridge piers; a2. During the simplification process of the bridge pier, the geometric shape and stiffness characteristics of the key load-bearing parts shall be retained; a3. During the simplification process, the bow section is retained and counterweights are added; a4. The mechanical properties of the simplified ship model remain similar to those of the ship prototype.

3. The shrinking method for ship-bridge collision test according to claim 1, characterized in that: The simplified ship-bridge collision model ensures that the mechanical response, stress propagation path and energy dissipation characteristics during the collision are consistent with the prototype model.

4. The shrinking method for ship-bridge collision test according to claim 1, characterized in that: Step B: Establish the ship-bridge collision dynamics similarity model. The specific process is as follows: b1. Construct a scaled-down framework for the ship-bridge collision dynamics model based on the similarity of unchanged materials; b2. Based on the simplified model, establish geometric similarity with the reduced mold frame; b3. Based on the simplified model, establish the dynamic similarity with the reduced mold frame; b4. Based on the simplified model, establish kinematic similarity with the reduced mold frame.

5. The shrinking method for ship-bridge collision test according to claim 1, characterized in that: Step b2 is to establish geometric similarity with the reduced mold frame based on the simplified model, as follows: First, geometric similarity requires that the prototype and model remain strictly consistent in shape and proportion; Then, geometric similarity ensures that the geometric features of the structure are not distorted.

6. The shrinking method for ship-bridge collision test according to claim 1, characterized in that: Step b3 is based on the simplified model and establishes the dynamic similarity with the reduced mold frame, as follows: First, dynamic similarity requires that the prototype and the model be consistent in mechanical properties and response relationships; Then, dynamic similarity ensures that the inertial forces are consistent with the prototype.

7. The shrinking method for ship-bridge collision test according to claim 1, characterized in that: Step b4 is based on the simplified model and establishes kinematic similarity with the reduced mold frame, as follows: First, kinematic similarity requires that the prototype and the model be consistent in motion trajectory, velocity distribution, and deformation pattern; Then, kinematic similarity ensures that the motion processes of the prototype and the model remain similar in time scale.

8. The shrinking method for ship-bridge collision test according to claim 1, characterized in that: Step C: Based on the established mechanical similarity model, the bridge collision reduction model is verified. The specific process is as follows: First, after the scaled-down model is constructed, the consistency of the results between the scaled-down model and the prototype model is verified through simulation calculations, thereby evaluating the reliability and accuracy of the scaled-down model. Then, analyze the energy consumption path, select specific verification indicators, and define the corresponding error range; Then, analyze the force-displacement curve, select specific verification indicators, and define the corresponding error range; Finally, analyze the failure mode, select specific verification indicators, and define the corresponding error range.

9. The shrinking method for ship bridge collision test according to claim 1, characterized in that: Step D performs iterative optimization of the shrink mold model based on the shrink mold verification results. The specific process is as follows: First, based on the similarity of unchanged materials, determine the model optimization object: Then, the structure of the model optimization object is optimized.

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