Method for testing ice breaking total force and ice load space distribution state in upward-floating ice breaking process

Abstract

The invention relates to a method for testing an ice breaking total force and an ice load space distribution state in a floating ice breaking process, and belongs to the technical field of ice pool model tests. Comprising the following steps: a model is located below an ice cover; controlling the model to float at a preset speed, and simulating a floating icebreaking process; in the upward-floating icebreaking process, the total ice load borne by the model and the local ice load of each subsection model are measured synchronously, and the spatial distribution state of the ice loads is obtained; based on an inertia force interference elimination system, inertia force calibration and correction are carried out on ice load data obtained through measurement, and the corrected net ice load is obtained. When the ice load test is carried out, inertia force interference can be effectively eliminated in real time, and the accuracy of a test result is ensured.

Description

Technical Field

[0001] This invention relates to a method for testing the floating and ice-breaking state, belonging to the technical field of ice-water pool model testing. Background Technology

[0002] Global warming is causing the gradual melting of polar sea ice, driving an increase in polar scientific research, commercial, and resource development activities. Against this backdrop, underwater vehicles (UVs) may need to perform icebreaking missions during polar operations due to real-time communication or emergency needs. Unlike conventional ship icebreaking, underwater vehicle icebreaking involves the fracture and failure process of the ice sheet under vertical loads. During this process, the spatial distribution of ice loads on the structure is crucial to the structural strength and maneuverability design of the vehicle. However, this process involves complex multiphysics coupling and the variable physical and mechanical properties of sea ice materials, and the academic and engineering communities both domestically and internationally have not yet established a comprehensive and effective research and testing methodology.

[0003] Currently, some scholars have conducted exploratory research on this problem using numerical simulation methods, introducing methods such as the finite element method, discrete element method, smoothed particle method, and peri-field dynamics into the field of ice mechanics. Hu Xinyun (2022) established an underwater vehicle-ice-water coupling model based on the SPH-FEM algorithm, quantifying the influence of factors such as ice thickness and surfacing velocity on the spatial distribution gradient of the load. Wang et al. (2021) used LS-DYNA software to simulate the process of an underwater vehicle breaking through ice and emerging from the water vertically, incorporating the nonlinear interaction between the structure, ice, and water. Yue et al. (2021) determined the main control parameters during the structure's surfacing and ice-breaking process through dimensional analysis, and then studied the dynamic characteristics of ice loads under different initial velocities. Ye et al. (2018) established an aerodynamic mathematical model to simulate the structure's surfacing and ice-breaking process and analyzed the temporal characteristics of the ice load. Ye Liyu et al. (2018) used peri-field dynamics to simulate the contact process between the underwater vehicle and the ice sheet, tracking the ice sheet failure morphology and load distribution through a contact detection algorithm. Liu Junjie et al. (2015) simplified the icebreaking process of the structure's ascent into a multi-body impact process, and then analyzed the coupling effect between impact forces.

[0004] In model testing, researchers have focused on collision tests between ice and typical local structures. Yu Shuang et al. (2024) applied a concentrated vertical load to freshwater ice in the field and recorded the ice failure process using displacement sensors and high-speed cameras. Lee et al. (2014) placed multiple strain measurement points on the inner side of the hull plating to record structural deformation during loading. Kim et al. (2014) used free-fall impact with ice samples to observe the deformation of the plate frame structure and the spatial distribution of ice loads. Choi et al. (2012) simulated the impact of steel plates on ice in the laboratory, testing the impact force and ice failure modes under different conditions by controlling the inclination angle and impact velocity of the steel plates. Gagnon (2004) used model ice to simulate the collision process between floating ice and the hull, measuring the contact pressure time history on the surface of the model.

[0005] In summary, existing research on the icebreaking process of underwater submersibles mainly includes two methods: numerical simulation and local structural experiments. With the continuous development of methods such as the finite element method, discrete element method, and peri-field dynamics, numerical simulation methods can now reproduce the entire process from submersible-ice sheet contact to failure relatively completely. However, due to the complexity of the constitutive relationship of ice materials, the calculation results still need to be verified by physical model experiments or field tests. Physical model experiments, limited by geometric scaling and laboratory conditions, can only test local structures of the submersible and cannot simulate the icebreaking process of the entire submersible. Because there are significant coupling effects between different parts of the submersible's structure during the icebreaking process, the results of icebreaking tests on individual local structures will inevitably deviate from the results of icebreaking at the corresponding parts of the complete submersible structure.

[0006] The invention disclosed in CN120141793A, entitled "A Test Method for the Spatial Distribution of Load on the Ascent and Icebreaking of an Underwater Submersible," addresses the issue that the vertical motion of the submersible model is significantly affected by the weight of the model and mechanism. This leads to inaccurate load test results during the submersible's ascent and icebreaking due to the inertial force of the model and mechanism. To solve this problem, a test method for the spatial distribution of load on the ascent and icebreaking of an underwater submersible is urgently needed.

[0007] Therefore, it is urgent to propose a test method for the spatial distribution of total ice-breaking force and ice load during the surfacing and ice-breaking process in order to solve the above-mentioned technical problems. Summary of the Invention

[0008] To address the aforementioned problems, a method for testing the spatial distribution of total ice-breaking force and ice load during the icebreaking process is provided. A brief overview of this invention is given below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0009] The technical solution of this invention:

[0010] A test method for the spatial distribution of total icebreaking force and ice load during the surfacing and icebreaking process includes the following steps: The model is located below the ice sheet; the model is controlled to rise at a predetermined speed to simulate the ice-breaking process; during the ice-breaking process, the total ice load on the model and the local ice load of each segment of the model are measured simultaneously to obtain the spatial distribution of the ice load; based on the inertial force interference elimination system, the measured ice load data is calibrated and corrected to obtain the corrected net ice load.

[0011] Preferably, a testing device for mounting a model is provided below the ice sheet, the testing device comprising: One end of the upright limb is connected to the output end of the lifting servo device, and the other end of the upright limb is connected to one end of the horizontal limb. The other end of the horizontal limb is connected to the rigid base through a hinge seat. Both sides of the hinge seat are respectively provided with detachable connections to the horizontal limb. The rigid base is supported above the pad block. The test unit is set on the rigid base, and a model is set on the test unit.

[0012] Preferably, the model is a segmented submersible model, wherein the model is segmented at the point of abrupt change in the linear structure of the model, and each segment of the model corresponds to a set of test units.

[0013] Preferably, the test unit includes a force sensor and a velocity sensor for simultaneously measuring the ice load and motion response of the model.

[0014] Preferably, the method includes the following steps: S1. Prepare a model ice sheet in an ice water tank; S2. Place the test device with the model installed at a predetermined position in the ice water pool, so that it is located below the ice cover of the model; S3. The model is controlled to rise at a predetermined speed by the lifting servo device to simulate the process of rising and breaking ice. S4. During the icebreaking process, the total ice load on the model and the local ice load of each segment model are measured synchronously through the test unit to obtain the spatial distribution of the ice load. S5. Based on the inertial force interference elimination system, the measured ice load data is calibrated and corrected to obtain the corrected net ice load.

[0015] Preferably, the preparation of the model ice sheet in step S1 includes the following steps: S101. Reduce the ambient temperature of the ice water pool to -20℃~-25℃ and keep it uniform; S102. Use an industrial spray gun to spray water at 28℃~30℃ at 19~21 atmospheres onto the surface of the ice pool to induce crystal growth. S103. During the spray crystallization process, turn off the cooling air supply and control the water surface wind speed to be below 0.1m / s; S104. After the crystal is generated, continue to cool down to allow the ice cap to grow to the predetermined thickness.

[0016] Preferably, in step S5, the inertial force interference cancellation system corrects the data through the following steps: S501. Before the test, weigh each segment of the model and the testing device to obtain the mass parameters; S502. Conduct a floating calibration test in an ice-free still water environment, repeating the test multiple times to obtain the motion response and force measurement data of each segment model. S503. Calculate the equivalent mass, damping coefficient, and offset parameters of each segment based on the calibration data. S504. In the formal test, the ice load measured in each segment is corrected in real time based on the following formula:

[0017] In the formula, F ice,i (t) represents the net ice load of the i-th segment; F meas,i (t) represents the data measured by the force sensor in the i-th segment; m eff,i The equivalent mass of the i-th segment model consists of the segment model mass, the test device mass, and the added mass; c 1,i c is the piecewise linear damping coefficient for the i-th segment; 2,i b is the second-order damping coefficient for the i-th segment; i For the i-th segment, bias; v i (t) represents the vertical velocity of the i-th segment; a i (t) represents the vertical acceleration of the i-th segment.

[0018] Preferably, the range of the test unit is estimated based on a semi-theoretical, semi-empirical formula for the vertical destructive force of the ice layer under the surface contact ice-breaking mode. The formula is:

[0019] Among them, P f σ represents the vertical failure load of the ice layer when a circumferential crack penetrates; N denoted as , where h is the flexural strength of the ice layer; is the thickness of the ice layer; k is a dimensionless constant; R is the radius of failure of the ice layer; and L is the characteristic length of the ice layer.

[0020] Where E is the elastic modulus of ice; υ is the Poisson's ratio of ice; ρ w ρ is the density of water; g is the acceleration due to gravity.

[0021] Preferably, when the submersible segment model is arranged, the distance between its edge and the free boundary of the ice sheet and the pool wall is not less than 1 times the characteristic length L of the ice layer.

[0022] The present invention has the following beneficial effects: This invention features targeted adaptive designs for different ice-water pool environments, effectively simulating the surfacing and ice-breaking behavior of underwater submersibles, and accurately controlling the movement speed and stroke of the structural model. This invention is adapted to the segmented model of an underwater submersible. It rationally designs the range and sensitivity of the test unit and selects test elements that meet the requirements for low temperature resistance, anti-interference and waterproof performance. It reduces inertial force interference in real time and realizes accurate measurement of the total ice-breaking force and ice load distribution of the segmented model of the underwater submersible. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the testing device structure of the present invention; Figure 2 This is a schematic diagram of the testing device of the present invention from another perspective; Figure 3 This is a time history diagram of the ice load test results of the model segment before correction by the inertial force correction system of this invention; Figure 4 This is a time history diagram of the ice load test results of the segmented model after correction by the inertial force correction system of this invention; In the diagram, 1-connecting plate, 2-vertical limb, 3-horizontal limb, 4-rigid base, 5-test unit, 6-model, 7-hinge seat, 8-pad, 9-lifting servo device, 10-model ice cover. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0025] Specific implementation method one: Combining Figure 1-3 This embodiment describes a method for testing the spatial distribution of total ice-breaking force and ice load during the buoyancy and ice-breaking process, comprising the following steps: Model 6 is located below ice sheet 10; Model 6 is controlled to rise at a predetermined speed to simulate the ice-breaking process; during the ice-breaking process, the total ice load on Model 6 and the local ice load of each segment of the model are measured simultaneously to obtain the spatial distribution of the ice load; based on the inertial force interference elimination system, the measured ice load data is calibrated and corrected to obtain the corrected net ice load; this invention can eliminate inertial force interference in real time and effectively during ice load testing, ensuring the accuracy of the test results.

[0026] Specific Implementation Method Two: Combining Figure 1-3 This embodiment describes a method for testing the total ice-breaking force and spatial distribution of ice load during the ice-breaking process. A testing device for mounting the model 6 is provided below the ice cover 10. The testing device includes: a connecting plate 1, a vertical limb 2, a horizontal limb 3, a rigid base 4, a testing unit 5, a hinge seat 7, a pad 8, and a lifting servo device 9. One end of the vertical limb 2 is connected to the output end of the lifting servo device 9 via a connecting plate 1. The lifting servo device 9 is fixed relative to the side wall of the ice water pool. The lifting servo device 9 can be a linear motor, used to realize the vertical movement of the model 6 driven by the test device. The other end of the vertical limb 2 is connected to one end of the horizontal limb 3. The other end of the horizontal limb 3 is connected to the rigid base 4 via a hinge seat 7. Both sides of the hinge seat 7 are respectively provided with detachable connections to the horizontal limb 3. The rigid base 4 is supported above the pad 8. The angle of the rigid base 4 can be adjusted by replacing the pads 8 of different thicknesses. Several sets of test units 5 are evenly arranged on the rigid base 4. The test unit 5 is equipped with a model 6. This invention designs a test device for simulating the surfacing and ice-breaking process of an underwater submersible and for testing the spatial distribution of ice load. It has been designed to adapt to different ice-water pool environments. The device can effectively simulate the surfacing and ice-breaking behavior of an underwater submersible and accurately control the movement speed and stroke of the structural model. At the same time, the device is adapted to the segmented model of the underwater submersible. The range and sensitivity of the test unit are reasonably designed, and test elements with low temperature resistance, anti-interference and waterproof performance are selected to reduce inertial force interference in real time. This enables accurate measurement of the total ice-breaking force and ice load distribution of the segmented model of the underwater submersible.

[0027] Specific implementation method three: Combining Figure 1-3 This embodiment describes the method for testing the spatial distribution of total ice-breaking force and ice load during the surfacing and ice-breaking process. Model 6 is a segmented submersible model. The model 6 is segmented at abrupt changes in the linearity of its structure, and each segment has a similar length. Each segment of the model 6 corresponds to a set of test units 5. Gaps are provided between the various segments of the model 6, and each segment is connected to the surfacing simulation component by a test unit 5. Along the length of the submersible segment model 6, the length of each segment structure is no more than 6 times the length of the test unit 5; along the width of the submersible segment model 6, the bottom contact width of each segment structure is no more than 8 times the width of the test unit 5. When the segment length is no more than 3 times the length of test unit 5, one test unit 5 is arranged in the middle of the segment; When the segment length is greater than 3 times but not more than 6 times the length of test unit 5, one test unit 5 is arranged at each end of the segment at a distance of 1 test unit 5 from the edge. When the bottom contact width of the segment is no more than 4 times the width of test unit 5, one test unit 5 is arranged in the width direction; When the bottom contact width of the segment is greater than 4 times but not more than 8 times the width of the test unit 5, one test unit 5 is arranged on each side of the width direction at a distance of 1.5 times the width of the test unit 5 from the contact edge.

[0028] Specific implementation method four: Combination Figure 1-3 This embodiment describes a method for testing the spatial distribution of total ice-breaking force and ice load during the ice-breaking process. Test unit 5 includes a force sensor and a velocity sensor, used to simultaneously measure the ice load and motion response of the model.

[0029] Specific Implementation Method Five: Combining Figure 1-3 This embodiment describes a method for testing the spatial distribution of total ice-breaking force and ice load during the buoyancy and ice-breaking process. The method includes the following steps: S1. Prepare model ice sheet 10 in ice water pool; S2. Place the test device with model 6 installed at a predetermined position in the ice water pool, so that it is located below the model ice cover 10; S3. The lifting servo device 9 controls the model 6 to rise at a predetermined speed to simulate the process of rising and breaking ice. S4. During the icebreaking process, the total ice load on the model 6 and the local ice load on each segment model are measured synchronously by the test unit 5 to obtain the spatial distribution of the ice load. S5. Based on the inertial force interference elimination system, the measured ice load data is calibrated and corrected to obtain the corrected net ice load.

[0030] Specific Implementation Method Six: Combination Figure 1-3 This embodiment describes the method for testing the spatial distribution of total ice-breaking force and ice load during the ice-breaking process. The preparation of the model ice sheet 10 in step S1 includes the following steps: S101. Reduce the ambient temperature of the ice water pool to -20℃~-25℃ and keep it uniform; S102. Use an industrial spray gun to spray water at 28℃~30℃ at 19~21 atmospheres onto the surface of the ice pool to induce crystal growth. S103. During the spray crystallization process, turn off the cooling air supply and control the water surface wind speed to be below 0.1m / s; S104. After the crystal is generated, continue to cool down to allow the ice cap to grow to the predetermined thickness.

[0031] Specific implementation method seven: Combining Figure 1-3 This embodiment describes the method for testing the spatial distribution of total ice-breaking force and ice load during the buoyancy and ice-breaking process. In step S5, the inertial force interference elimination system corrects the data through the following steps: S501. Before the test, weigh each segment of the model and the testing device to obtain the mass parameters; S502. Conduct a floating calibration test in an ice-free still water environment, repeating the test multiple times to obtain the motion response and force measurement data of each segment model. S503. Calculate the equivalent mass, damping coefficient, and offset parameters of each segment based on the calibration data. S504. In the formal test, the ice load measured in each segment is corrected in real time based on the following formula:

[0032] In the formula, F ice,i (t) represents the net ice load of the i-th segment; F meas,i (t) represents the data measured by the force sensor in the i-th segment; m eff,i The equivalent mass of the i-th segment model consists of the segment model mass, the test device mass, and the added mass; c 1,i c is the piecewise linear damping coefficient for the i-th segment; 2,i b is the second-order damping coefficient for the i-th segment; i For the i-th segment, bias; v i (t) represents the vertical velocity of the i-th segment; a i (t) represents the vertical acceleration of the i-th segment.

[0033] Specific implementation method eight: Combination Figure 1-3 This embodiment describes the testing method for the spatial distribution of total ice-breaking force and ice load during the buoyancy ice-breaking process. The range of the testing unit 5 is estimated based on a semi-theoretical, semi-empirical formula for the vertical destructive force of the ice layer under the surface contact ice-breaking mode. The formula is:

[0034] Among them, P f σ represents the vertical failure load of the ice layer when a circumferential crack penetrates; Ndenoted as , where h is the flexural strength of the ice layer; is the thickness of the ice layer; k is a dimensionless constant; R is the radius of failure of the ice layer; and L is the characteristic length of the ice layer.

[0035] Where E is the elastic modulus of ice; υ is the Poisson's ratio of ice; ρ w ρ is the density of water; g is the acceleration due to gravity.

[0036] Specific Implementation Method Nine: Combining Figure 1-3 This embodiment describes the method for testing the spatial distribution of total ice-breaking force and ice load during the surfacing and ice-breaking process. When the submersible segment model 6 is arranged, the distance between its edge and the free boundary of the ice sheet and the pool wall is not less than 1 times the characteristic length L of the ice layer.

[0037] When simulating underwater structure lifting and icebreaking, the vertical force measured by traditional force sensors includes inertial force interference caused by acceleration, deceleration, and attitude changes during the lifting mechanism's upward movement. This invention employs a combination of sensing hardware and algorithm software in the test unit to form an inertial force interference cancellation system, effectively reducing inertial force interference during testing. On the hardware side, the test unit, located below each structural segment, includes force sensors and velocity sensors. All test units are connected to the same multi-channel data acquisition system, which uses a unified clock for synchronous sampling, measuring the vertical force and velocity response of each segment model. Regarding the testing process, inertial force parameters are determined through pre-test weighing and underwater calibration. The test data for each segment is then corrected online in real-time according to the following formula, reducing the interference of inertial force on the net ice load. The actual effect of this testing method is Figure 3 The example shows that Figure 3 The left-middle figure shows the time history of the vertical force and the time history of the structural model motion response directly measured by the force sensor. It can be seen from the vertical force time history that it is significantly affected by the structural motion relationship. After processing by the software and hardware method of this patent, the time history curve in the right figure is obtained. This curve is the ice-breaking load time history of the model after eliminating the interference of inertial force, thereby effectively improving the testing accuracy of the device for ice-breaking load.

[0038] Example 1: Combination Figure 1-4 The device shown is a test apparatus for measuring the spatial distribution of ice-breaking loads during the surfacing of an underwater submersible. It has two basic functions: simulating the ice-breaking process of an underwater submersible model in an ice-water pool, and simultaneously measuring the total ice load and the spatial distribution of the loads on the submersible model during the ice-breaking process. To achieve these functions, reference is made to… Figure 1 and Figure 2The device consists of an ascent simulation component and a load testing component. The ascent simulation component includes a vertical limb 2, a horizontal limb 3, and a rigid base 4. The vertical limb 2 is used to extend the diving depth of the submersible segment model 6. The upper end of the vertical limb 2 is bolted to the lifting arm of the lifting servo device 9, and the lower end of the vertical limb 2 is welded to the horizontal limb 3. The lifting arm is the main component that drives the vertical movement of the ascent simulation component and controls its speed, and is driven and controlled by the servo system. One end of the horizontal limb 3 is welded to the vertical limb 2, and the other end extends horizontally to extend the submersible segment model 6 under the ice sheet. Two diagonal braces extend from the ends of the horizontal limb 3 to the sides, forming a triangular support structure to support the rigid base 4. The rigid base 4 is used to install the submersible segment model 6. Referring to the shape of the underwater submersible, the rigid base 4 is slender and connected to the lower horizontal limb 3 at three points. The middle part is connected to the end of the horizontal limb 3 through a hinge seat 7, and the two sides are bolted to the corner positions where the horizontal limb 3 extends to the sides through pads 8.

[0039] In this embodiment, the vertical limb 2 is 0.5m high and is bolted to the lifting servo device 9 via the connecting plate 1, serving to lower the submersible segment model 6. The lifting servo device 9 has a rated power of 13kW, can provide a maximum lifting force of 2t, a maximum lifting rate of 300mm / s, and a rate control accuracy of 1mm / s. The horizontal limb 3 is 3.5m long and serves to extend the submersible segment model 6 under the ice. The length is designed based on the fact that the free end of the ice sheet is at least one characteristic length L away from the edge of the model, which can be calculated by formula. One end of the horizontal limb 3 is connected to the rigid base 4 via a hinge seat 7 and a pad 8. Both the hinge seat 7 and the pad 8 are bolted to the upper rigid base 4 and the lower horizontal limb 3. The length of the rigid base 4 is the same as the length of the underwater submersible model. Based on the linear characteristics and length of the submersible segment model 6, the model is divided into 10 segments, with one test unit 5 arranged under each segment. Test unit 5 is bolted to the rigid base 44 at the bottom and bolted to the corresponding segment of the model at the top to measure the ice-breaking load of that segment. A 2mm gap is left between each segment to avoid mutual interference of ice-breaking loads.

[0040] The load testing assembly consists of multiple identical test units 5 and data acquisition equipment. The test units 5 are arranged sequentially along the length of the rigid base 4, and are bolted to the upper submersible segment model 6 and the lower rigid base 4. This assembly measures the ice-breaking load distribution and inertial force of the underwater submersible. The segments of the submersible segment model 6 are not in contact and have a certain gap to avoid mutual interference between the measured loads of each segment. All test units 5 are of the same model and are connected to a single data acquisition device to ensure that all sensors synchronously collect load and velocity data at the same frequency. The underwater submersible model connected to the load testing assembly can be segmented according to its structural features. Considering that the lengths of each segment are similar, each segment is connected to the rigid base 4 via a test unit 5 to ensure the completeness of the ice load measurement results.

[0041] When designing the segmentation scheme for the underwater submersible segment model 6, it is necessary to ensure that segmentation occurs at locations where the structural lines abruptly change, and to guarantee the stability of the connections between each segment. This requires that the length and width of each segment be limited within a certain range, specifically referring to the following principles: Along the length direction of the submersible segment model 6, when the length of the model segment is less than or equal to three times the length of the test unit 5, one test unit 5 can be placed in the middle of the model segment; when the length of the model segment is greater than three times but less than or equal to six times the length of the test unit 5, one test unit 5 can be placed at the front and rear edges of the model segment at a distance of one test unit 5 length; when the length of the model segment is greater than six times the length of the test unit 5, the model segment can be further subdivided into ranges of less than three times the length or three to six times the length. It is also important to ensure that the length distribution of each segment is uniform.

[0042] Along the width direction of the submersible segment model 6, when the bottom contact width of the model is less than or equal to 4 times the width of the test unit 5, one sensor can be arranged in the width direction of the model; when the bottom contact width of the model is greater than 4 times but less than or equal to 8 times the width of the test unit 5, one test unit 5 can be arranged on each side of the model segment at a distance of 1.5 times the width from the contact edge.

[0043] On the other hand, when selecting the range of test unit 5, it is necessary to estimate the ice-breaking load of each model segment. A semi-theoretical and semi-empirical estimation method for the vertical destructive force of the ice layer under the surface contact ice-breaking mode can be used: (1) Among them, P f σ represents the vertical failure load of the ice layer when a circumferential crack penetrates; N Where is the bending strength of the ice layer; h is the ice layer thickness; k is a dimensionless constant; R is the ice layer failure radius; and L is the characteristic length of the ice layer, which can be calculated using the following formula: (2) In the formula, E is the elastic modulus of ice; υ is the Poisson's ratio of ice; ρ w This is the density of water.

[0044] The range of the force sensor in each test unit 5 can be determined according to P in formula (1). f The model was estimated and selected, and a product model with good low-temperature resistance, anti-interference, and waterproof performance was chosen. The velocity sensor model can be determined based on pre-test weighing and underwater calibration tests. All test units 5 were connected to the same data acquisition equipment, with a sampling frequency of not less than 50Hz set to ensure synchronous acquisition of the ice-breaking load and velocity time history of each segment structure.

[0045] A test method for the spatial distribution of ice-breaking loads on an underwater submersible during surfacing, the method using the aforementioned test apparatus, includes the following steps: S1. Prepare a model ice sheet in an ice water tank; The model ice cap is prepared through a process involving refrigeration, spray crystal induction, and temperature control. First, the temperature of the cryogenic chamber containing the ice-water pool is lowered to -20℃ to -25℃ (-22℃ in this example), ensuring uniform temperature throughout with a difference of no more than 0.5℃. Then, spray crystal induction begins, using an industrial spray gun with a pressure of 19-21 atmospheres to spray water at 28℃-30℃ onto the surface of the ice pool. In this example, the spray gun pressure is 20 atmospheres, and the water temperature is 30℃. The micro-atomized water droplets sprayed into the air above the ice pool rapidly absorb cold as they fall, forming tiny ice crystals that evenly settle on the surface. During this process, the wind speed above the water surface must be controlled to be below 0.1 m / s. Because the surface of the aqueous solution in the pool is already at freezing point, the falling micro-ice crystals do not melt, thus controlling the ice crystal lattice size and inducing the formation of the ice cap. Continued cooling of the air causes the ice crystals to grow continuously from top to bottom. The purpose of spray crystallization is to control the size of the ice crystal lattice. The entire spray crystallization process is carried out with the refrigeration unit shut off and the air supply stopped to avoid disturbing the water surface and causing breakage and unevenness of the ice crystal nuclei. Once a stable connection has been initially formed between the ice crystal nuclei, the cooling process is restarted. Cooling continues until the ice cap grows to the predetermined thickness, at which point the system is shut down, and preparations are made to begin the experiment.

[0046] S2. The test device with the submersible segment model installed is placed at a predetermined position in the ice water pool, so that it is located below the ice cover of the model; Install the submersible segment model and place it at a predetermined position in the ice-water pool. Use a lifting servo device to position the submersible segment model at a certain distance and depth under the ice, ensuring that the edges of the structural model maintain a distance of more than 1 feature length from the free boundary of the ice sheet and the pool wall.

[0047] S3. Control the submersible segment model to rise at a predetermined speed through the lifting servo device to simulate the ice-breaking process. S4. During the surfacing and icebreaking process, the total ice load on the submersible segment model and the local ice load on each segment model are measured simultaneously through the test unit to obtain the spatial distribution of the ice load. S5. Based on the inertial force interference elimination system, the measured ice load data is calibrated and corrected to obtain the corrected net ice load.

[0048] This embodiment focuses on the load problem of an underwater submersible model during vertical motion. Acceleration, deceleration, and attitude changes during surfacing and icebreaking generate inertial force interference. The sensor hardware and algorithm software in the test unit combine to form an inertial force interference cancellation system, which can effectively reduce inertial force interference during testing. In terms of hardware, the test unit, located below each segment structure, includes force sensors and velocity sensors. Each test unit is connected to the same multi-channel data acquisition system, which uses a unified clock for synchronous sampling to measure the vertical force and velocity response of each segment model. In terms of the test procedure, the parameters affecting inertial forces are determined through pre-test weighing and underwater calibration. The test data for each segment are then corrected online in real time according to the following formula to reduce the interference of inertial forces on the net ice load: (3) In the formula, F ice,i (t) represents the net ice load of the i-th segment; F meas,i (t) represents the data measured by the force sensor in the i-th segment; m eff,i The equivalent mass of the i-th segment model consists of the segment model mass, the test device mass, and the added mass; c 1,i c is the piecewise linear damping coefficient for the i-th segment; 2,i b is the second-order damping coefficient for the i-th segment; i For the i-th segment, bias; v i (t) represents the vertical velocity of the i-th segment; a i (t) represents the vertical acceleration of the i-th segment.

[0049] Understandably, F ice,i (t) is the corrected net ice load, F meas,i (t) represents the ice load measured by the sensor, and the subsequent terms in the formula are inertial force disturbance terms.

[0050] The general steps for inertial force calibration and test data correction using an inertial force interference cancellation system are as follows: S501. Weighing. Before the test, weigh each segment of the submersible model and the testing device to determine the mass of each segment and the mass of the testing device.

[0051] S502. Underwater Calibration. After installing all sections of the model and the testing system, lower the test object to the predetermined underwater position, ensuring the water surface is ice-free. In still water, force the test device to rise at the buoyancy rate set for the actual test. The initial and final positions of the rise should be consistent with those in the actual test. Each calibration test should be repeated at least twice.

[0052] S503, Calibration Data Analysis. Record the time histories of the data measured by each velocity sensor and force sensor in each calibration test. Perform first-order differential processing on the velocity motion time history curve to obtain the acceleration time history curve of the corresponding model segment. Substitute the above test data into formula (3) to form a system of simultaneous equations to calculate the equivalent mass m of each model segment. eff,i Linear damping coefficient c 1,i Secondary damping coefficient c 2,i and bias b i Parameters such as these.

[0053] S504, Inertial Force Correction. In the formal test, the force sensor reading F in formula (3) can be measured. meas,i (t), vertical velocity v i (t), vertical acceleration a i Substituting the parameters determined in the calibration test into formula (3), the net ice load F after inertial force correction can be obtained. ice,i (t), thereby improving the accuracy of test results.

[0054] Specifically, during the simulated surfacing and icebreaking process, the total ice load and the spatial distribution of the ice load were measured simultaneously. The submersible segment model was controlled by the lifting servo device to surface and break the ice at a predetermined speed and stroke. In the entire test process, each test unit was first activated, and the load time history of the submersible segment model from static start to completion of the icebreaking process was recorded to obtain the force sensor reading F in formula (3). meas,i (t), vertical velocity v i (t), vertical acceleration a i Substituting the parameters determined in the calibration test into formula (3), the net ice load F after inertial force correction can be obtained. ice,i (t), thus accurately obtaining the total ice load and spatial distribution of the ice load of the underwater submersible model during the icebreaking process. For example... Figure 3 As shown, the left figure shows the ice force time history and motion response time history directly measured on a certain model segment. It can be seen that there is a significant correlation between the two, that is, the effect of inertial force will affect the ice force test results. The right figure shows the static ice load results after correction by the inertial force removal algorithm. It can be seen that compared with the original ice force time history curve, the interference of inertial force has been effectively eliminated.

[0055] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for testing the spatial distribution of total ice-breaking force and ice load during the surfacing and ice-breaking process, characterized in that: Includes the following steps: Model (6) is located below ice sheet (10); control model (6) to float up at a predetermined speed to simulate the floating and ice-breaking process; during the floating and ice-breaking process, the total ice load on model (6) and the local ice load of each segment model are measured simultaneously to obtain the spatial distribution state of ice load; based on the inertial force interference elimination system, the measured ice load data are calibrated and corrected to obtain the corrected net ice load.

2. The method for testing the spatial distribution of total icebreaking force and ice load during the buoyancy and icebreaking process according to claim 1, characterized in that: A testing device for mounting the model (6) is provided below the ice cap (10), the testing device comprising: One end of the upright limb (2) is connected to the output end of the lifting servo device (9), and the other end of the upright limb (2) is connected to one end of the horizontal limb (3). The other end of the horizontal limb (3) is connected to the rigid base (4) through the hinge seat (7). The two sides of the hinge seat (7) are respectively provided with detachable connections to the horizontal limb (3). The rigid base (4) is supported above the pad (8). The test unit (5) is set on the rigid base (4), and the model (6) is set on the test unit (5).

3. The method for testing the spatial distribution of total icebreaking force and ice load during the buoyancy and icebreaking process according to claim 2, characterized in that: Model (6) is a segmented model of a submersible. The model (6) is segmented at the point where the model structure changes linearly. Each segment of the model (6) is provided with a set of test units (5).

4. The method for testing the spatial distribution of total icebreaking force and ice load during the buoyancy and icebreaking process according to claim 2 or 3, characterized in that: The test unit (5) includes a force sensor and a velocity sensor, which are used to simultaneously measure the ice load and motion response of the model.

5. The method for testing the spatial distribution of total icebreaking force and ice load during the buoyancy and icebreaking process according to claim 4, characterized in that: The method includes the following steps: S1. Prepare a model ice sheet (10) in an ice water pool. S2. Place the test device with the model (6) installed at a predetermined position in the ice water pool, so that it is located below the ice cover (10) of the model; S3. The lifting servo device (9) controls the model (6) to float up at a predetermined speed to simulate the floating and ice-breaking process. S4. During the ice-breaking process, the total ice load on the model (6) and the local ice load of each segment model are measured synchronously through the test unit (5) to obtain the spatial distribution state of the ice load. S5. Based on the inertial force interference elimination system, the measured ice load data is calibrated and corrected to obtain the corrected net ice load.

6. The method for testing the spatial distribution of total icebreaking force and ice load during the buoyancy and icebreaking process according to claim 5, characterized in that: The preparation of the model ice sheet (10) in step S1 includes the following steps: S101. Reduce the ambient temperature of the ice water pool to -20℃~-25℃ and keep it uniform; S102. Use an industrial spray gun to spray water at 28℃~30℃ at 19~21 atmospheres onto the surface of the ice pool to induce crystal growth. S103. During the spray crystallization process, turn off the cooling air supply and control the water surface wind speed to be below 0.1m / s; S104. After the crystal is generated, continue to cool down to allow the ice cap to grow to the predetermined thickness.

7. The method for testing the spatial distribution of total icebreaking force and ice load during the buoyancy and icebreaking process according to claim 6, characterized in that: In step S5, the inertial force interference cancellation system corrects the data through the following steps: S501. Before the test, weigh each segment of the model and the testing device to obtain the mass parameters; S502. Conduct a floating calibration test in an ice-free still water environment, repeating the test multiple times to obtain the motion response and force measurement data of each segment model. S503. Calculate the equivalent mass, damping coefficient, and offset parameters of each segment based on the calibration data. S504. In the formal test, the ice load measured in each segment is corrected in real time based on the following formula: In the formula, F ice,i (t) represents the net ice load of the i-th segment; F meas,i (t) represents the data measured by the force sensor in the i-th segment; m eff,i The equivalent mass of the i-th segment model consists of the segment model mass, the test device mass, and the added mass; c 1,i c is the piecewise linear damping coefficient for the i-th segment; 2,i b is the second-order damping coefficient for the i-th segment; i For the i-th segment, bias; v i (t) represents the vertical velocity of the i-th segment; a i (t) represents the vertical acceleration of the i-th segment.

8. The method for testing the spatial distribution of total icebreaking force and ice load during the buoyancy and icebreaking process according to claim 7, characterized in that: The range of the test unit (5) is estimated based on a semi-theoretical, semi-empirical formula for the vertical destructive force of ice layer under surface contact ice breaking mode. The formula is: Among them, P f σ represents the vertical failure load of the ice layer when a circumferential crack penetrates; N denoted as , where h is the flexural strength of the ice layer; , where h is the ice layer thickness; , where k is a dimensionless constant; , where R is the ice layer failure radius; and , where L is the characteristic length of the ice layer. Where E is the elastic modulus of ice; υ is the Poisson's ratio of ice; ρ w ρ is the density of water; g is the acceleration due to gravity.

9. The method for testing the spatial distribution of total icebreaking force and ice load during the buoyancy and icebreaking process according to claim 8, characterized in that: When the submersible segment model (6) is arranged, the distance between its edge and the free boundary of the ice sheet and the pool wall is not less than 1 times the characteristic length L of the ice layer.

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