Ice block internal stress analysis method and system under action of underwater laser distribution array

Abstract

The invention discloses an ice block internal stress analysis method and system under the action of an underwater laser point distribution array, and belongs to the technical field of icebreaking. The ice block internal stress analysis method under the action of the underwater laser point distribution array comprises the steps that S1, a water power module is established and verified; s2, acquiring water flow force; s3, establishing an ice block solid mechanical module; s4, fitting a static pressure load equation and a pulse load equation; s5, performing coupling calculation and verification on the hydrodynamic module and the ice block solid mechanical module; s6, selecting and optimizing initial laser array stationing parameters; s7, comparing and selecting load types; and S8, calculating the distribution of the stress in the ice block at any time and space under the action of the pulse load and the water flow force. By applying the technical scheme, the rule of the maximum stress influence of the laser point distribution array on the interior of the ice block under the combined action of the water flow force and the mechanical load can be disclosed, and then the efficiency of the polar region ice breaking operation is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of ice breaking, and in particular relates to a method and system for analyzing the internal stress of ice blocks under the action of an underwater laser spot array. Background Art

[0002] As the world pays more and more attention to polar resources and waterways, the development of polar regions has become a strategic priority for many countries to compete for layout. However, since polar waters are widely covered with thick ice, especially in winter and cold seasons, these ice layers pose a significant obstacle to polar research, resource development and navigation, and there is an urgent need to overcome them through icebreaking technology. Traditional icebreaking technology mainly relies on mechanical means, but in extremely low temperature environments, these methods are usually inefficient, noisy, and easy to damage equipment. Therefore, in order to improve the efficiency of polar development and gain a competitive advantage, there is an urgent need to develop more efficient and environmentally friendly icebreaking technology in order to gain greater influence in polar resource development and international cooperation.

[0003] Compared with traditional mechanical icebreaking methods, laser technology has unique advantages in icebreaking. For example, no noise is generated during laser radiation, which not only reduces interference and damage to the marine ecosystem, avoids pollution to the surrounding environment, but also improves the concealment of icebreaking operations. Laser technology has high energy transmission efficiency and good directionality, and the high temperature it generates can melt the ice layer. Therefore, in the field of polar icebreaking, laser technology has great application potential and prospects. Despite this, the current application of laser icebreaking technology in actual engineering is mainly concentrated in power grid deicing, road ice melting, etc., while the actual application of polar icebreaking is almost blank. The laser can resonate with the target material and convert electromagnetic wave energy into heat energy. When the ice layer is thick enough, the laser energy will be completely absorbed, resulting in a temperature field distribution inside the ice layer, thereby increasing the maximum stress peak of the ice layer under the surface load and inducing cracks in the ice layer. Laser drilling is one of the earliest practical laser processing technologies. Therefore, by using a laser array to melt holes in the ice and locally destroy the ice structure, the external load required for icebreaking can be effectively reduced. In the future, combined with mechanical icebreaking technology, it is expected to achieve rapid icebreaking. Summary of the invention

[0004] Technical solution, in order to solve the technical problems in the above-mentioned background technology, a method and system for analyzing the internal stress of ice blocks under the action of underwater laser point array is proposed. By establishing a water tank numerical model to obtain water flow force, a three-dimensional solid mechanics model of ice blocks is constructed, and the static pressure load and pulse load external force equations are fitted. The local destructive effect caused by the laser point array on the surface of the ice block is combined with the mechanical external force and water flow force, and the response law of the maximum stress inside the ice block under different laser array point parameters is analyzed. This solution can help to deeply understand the impact of the laser point array on the stress state of the ice body, find the optimal laser array point parameters, provide a theoretical basis for laser-assisted mechanical icebreaking technology, and provide new measures for optimizing icebreaking strategies, improving icebreaking efficiency, and reducing noise pollution.

[0005] The first object of the present invention is to provide a method for analyzing the internal stress of ice blocks under the action of an underwater laser spot array, comprising:

[0006] S1. Establishment and verification of hydrodynamic module;

[0007] S2, obtain water flow force;

[0008] S3, establish ice solid mechanics module;

[0009] S4, fitting static pressure load equation and pulse load equation;

[0010] S5. Coupling calculation and verification of hydrodynamic module and ice solid mechanics module;

[0011] Referring to the laser array parameters set in the physical model experiment, the water flow force obtained in S2 and the static pressure load expression fitted in S4 are applied to the ice solid mechanics model, and stress measurement points are set corresponding to the jack head area in the physical experiment. After calculation, the simulation results are compared with the measured values ​​of the physical model to ensure that the relative error meets the requirements;

[0012] S6, selection and optimization of initial laser array point distribution parameters;

[0013] S7. Comparison and selection of load types;

[0014] S8. Calculate the distribution of internal stress of ice cubes in time and space under the action of pulse load and water flow force.

[0015] Preferably, S1 is specifically as follows: in order to obtain the water flow force acting on the ice cubes, a water tank numerical model of the interaction between water flow and fixed ice is established, the shear stress transport k-ωSST turbulence model is adopted, the fluid volume method is used for free interface capture, the finite volume method is used for spatial discretization, the coupling of velocity and pressure is realized by the PIMPLE algorithm, and the simulation results are compared with the measured flow velocity data to verify the accuracy and reliability of the numerical calculation method.

[0016] Preferably, S2 is specifically: the water flow force includes the drag force and lift acting on the ice cube; firstly, the velocity field, pressure field and stress tensor of the fluid are calculated, and then the total water flow force is obtained by integrating on the surface of the ice cube, and compared and verified with the under-ice water flow force under different water flow conditions obtained in the water tank physical model experiment, and the measured data is used as the water flow force applied to the solid mechanics model, and is applied to the stress analysis of different ice cubes under static pressure and pulse loads.

[0017] Preferably, S3 is specifically:

[0018] Obtaining the geometric dimensions of the ice block, including the overall length, width, height, and laser point distribution parameters of the internal structure, wherein the laser point distribution parameters include the number, depth, and spacing of holes;

[0019] Determine the physical and mechanical parameters of polar ice and clarify the mechanical loads applied to the ice; the physical parameters include density and specific heat capacity; the mechanical parameters include elastic modulus, Poisson's ratio, yield strength, and plastic strain.

[0020] Preferably, S4 is specifically: based on the experimental data of the laser-assisted static pressure load and pulse load icebreaking physical model, a mathematical expression of the static pressure load and pulse load changing with time is obtained by fitting through a combined algorithm of the quasi-Newton method and the general global optimization method.

[0021] Preferably, S6 is specifically as follows: based on the laser-assisted pulse load icebreaking physical model experiment, the initial laser array point distribution parameters are set, and through solid mechanics numerical simulation, a single factor sensitivity analysis of the laser array point distribution parameters is carried out, and based on the McQuarter method, the relationship equation between different laser point distribution parameters and the maximum stress inside the ice block is fitted, and the initial laser array point distribution parameter settings are optimized.

[0022] Preferably, S7 specifically comprises: applying the static pressure load equation and the pulse load equation to the ice block model with the same distribution parameters respectively, comparing the maximum stress value generated inside the ice block and the time required to reach the stress value, and selecting the load type with better ice breaking efficiency through comparative analysis.

[0023] Preferably, S8 is specifically: based on the relationship equation between different laser point distribution parameters and the maximum stress inside the ice block, the optimal laser array point distribution parameters are selected according to the actual situation, and then combined with the load with better icebreaking efficiency selected in S7 and the water flow force obtained in S2 to achieve the best mechanical effect in the icebreaking process and improve the icebreaking efficiency.

[0024] The second object of the present invention is to provide an ice block internal stress analysis system under the action of an underwater laser spot array, comprising:

[0025] Hydrodynamics module: Based on the shear stress transport k-ωSST turbulence model, a numerical model of a water tank for the interaction between water flow and fixed ice cubes is established. The free interface is captured using the fluid volume method, and the velocity and pressure coupling is achieved through the PIMPLE algorithm. The water flow force including drag force and lift is obtained. The total water flow force is obtained by calculating the fluid velocity field, pressure field and stress tensor, integrating the ice surface force distribution, and comparing it with the physical experimental data to verify the accuracy of the model;

[0026] Ice solid mechanics module: Based on continuum mechanics, the momentum conservation equation and elastoplastic constitutive relation are used to describe the stress and strain of ice. The boundary conditions are static pressure and pulse load, and the mechanical boundary is set as a fixed constraint to verify the maximum stress at the indenter position. When the model is established, the geometric dimensions of the ice, laser point distribution parameters, and physical and mechanical parameters of the ice are obtained, and the analysis is carried out in combination with the applied load.

[0027] Fitting static pressure load and pulse load equation module: Based on the experimental data of laser-assisted static pressure load and pulse load icebreaking physical model, the mathematical expressions of static pressure load and pulse load changing with time are fitted through the combined algorithm of quasi-Newton method and general global optimization method;

[0028] Coupling calculation and verification module of hydrodynamic model and ice solid mechanics model: referring to the laser array parameters set in the physical model experiment, the water flow force obtained in the hydrodynamic module and the static pressure load expression fitted in the static pressure load fitting and pulse load equation modules are applied to the model established in the ice solid mechanics module, and stress measurement points are set in the jack head area in the physical experiment. After calculation, the simulation results are compared with the measured values ​​of the physical model to ensure that the relative error meets the requirements;

[0029] Selection and optimization module of initial laser array point distribution parameters: According to the laser-assisted pulse load icebreaking experiment, the initial laser array point distribution parameters are set, and single-factor sensitivity analysis is performed through solid mechanics numerical simulation. The relationship between the laser point distribution parameters and the maximum stress of ice blocks is fitted based on the Macquart method, and the initial parameter settings are optimized to improve the icebreaking effect;

[0030] Load type comparison and selection module: The static pressure load equation and the pulse load equation are applied to the ice block model with the same distribution parameters, and the maximum stress value generated inside the ice block and the time required to reach the stress are compared to evaluate the ice-breaking effect of the two load types and select the load type with better ice-breaking efficiency;

[0031] Module for calculating the distribution of internal stress of ice cubes in time and space under the action of pulse loads and water flow forces: Based on the selection of initial laser array point distribution parameters and the relationship equation between the laser point distribution parameters fitted in the optimization module and the maximum internal stress of the ice cube, the optimal laser array point distribution parameters are selected according to the actual situation, and combined with the dominant load in the load type comparison selection module and the water flow force obtained in the hydrodynamic module to achieve the best icebreaking mechanical effect.

[0032] The third invention objective of this patent is to provide a computer program product, including a computer program, which, when executed by a processor, implements the above-mentioned method for analyzing the internal stress of ice blocks under the action of the underwater laser spot array.

[0033] The fourth invention objective of this patent is to provide a computer-readable storage medium, including instructions, which, when run on a computer, enables the computer to execute the above-mentioned method for analyzing the internal stress of ice blocks under the action of an underwater laser spot array.

[0034] The advantages and positive effects of the present invention are:

[0035] The present invention first obtains the water flow force on the ice by establishing and verifying the hydrodynamic model; then the solid mechanics model of the ice is established using the physical properties and mechanical parameters of polar ice. Based on the laser-assisted icebreaking physical experiment, the external force equations of the static pressure load and the pulse load are fitted. The fitted static pressure load equation and the water flow force are applied to the solid mechanics model of the ice, and the simulation results are compared with the physical experimental data to ensure that the relative error is low and verify the accuracy of the model. Then, based on the laser-assisted static pressure load icebreaking physical model experiment, the initial laser array point distribution parameters are set, and the relationship equation between different laser point distribution parameters and the maximum stress inside the ice is fitted through the single factor sensitivity analysis of the point distribution parameters. Finally, the static pressure load equation and the pulse load equation are respectively applied to the ice model with the same point distribution parameters, and the effects of the two loads on the maximum stress value and action time inside the ice are compared, and the load type with better icebreaking efficiency is selected. The optimal point distribution parameters are selected through the relationship equation between the laser point distribution parameters and the maximum stress inside the ice, and the optimal ice-breaking effect is achieved by combining the advantageous load and water flow force, thereby significantly improving the ice-breaking efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flowchart of a preferred embodiment of the present invention;

[0037] Figure 2 A numerical model diagram of a water tank in which water flow and ice sheets interact in a preferred embodiment of the present invention;

[0038] Figure 3 The drag force and corresponding flow velocity diagram obtained by numerical simulation of the water tank in the preferred embodiment of the present invention;

[0039] Figure 4 This is an example diagram of the solid mechanics model of ice in a preferred embodiment of the present invention;

[0040] Figure 5 It is a static pressure load pressure-time curve diagram fitted in a preferred embodiment of the present invention;

[0041] Figure 6 It is a pressure-time curve diagram after the three sections of pulse load curve fitted in the preferred embodiment of the present invention are merged;

[0042] Figure 7 This is a verification comparison diagram of the maximum stress of the indenter in the preferred embodiment of the present invention;

[0043] Figure 8 A curve diagram showing the variation of the maximum stress inside the ice block with the number of holes in a preferred embodiment of the present invention;

[0044] Fig. 9 It is a curve diagram showing the variation of the maximum stress inside the ice block with the hole depth in the preferred embodiment of the present invention;

[0045] Fig.10 It is a curve diagram showing the variation of the maximum stress inside the ice block with the hole spacing in the preferred embodiment of the present invention;

[0046] Fig.11 The stress distribution diagram of the cross section where the maximum stress value inside the ice block is located at the time t=0.005s in the 3*3 point distribution mode in the preferred embodiment of the present invention;

[0047] Fig.12 The stress distribution diagram of the cross section where the maximum stress value inside the ice block is located at the time t=0.001s when the hole depth is 80mm in the preferred embodiment of the present invention;

[0048] Fig.13 The stress distribution diagram of the cross section where the maximum stress value inside the ice block is located at the time t=0.001s with a hole spacing of 80mm in the preferred embodiment of the present invention;

[0049] Fig.14 This is a diagram of stress distribution and maximum stress value under static pressure load when the number of points is 2*2, the depth is 200mm, and the spacing is 6.67mm in the preferred embodiment of the present invention;

[0050] Fig.15 This is a diagram of stress distribution and maximum stress value under pulse load when the number of points is 2*2, the depth is 200mm, and the spacing is 6.67mm in the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings.

[0052] The present invention adopts laser-assisted icebreaking technology, which effectively promotes local destruction and weakens the overall structural strength by forming a hole array on the surface of the ice body, thereby significantly reducing the difficulty of subsequent icebreaking operations and reducing noise. To this end, the present invention constructs a numerical model of the water tank to obtain water flow force, establishes a three-dimensional solid mechanics model of the ice block, and fits the external force equations of static pressure load and pulse load. By combining the local destructive effect produced by the laser point array on the surface of the ice block with the action of mechanical external force and water flow force, the variation law of the maximum stress inside the ice block under different laser array point parameters is analyzed. This method helps to deeply understand the influence of the laser point array on the stress state of the ice body, determine the optimal laser array point parameters, provide theoretical support for laser-assisted mechanical icebreaking technology, and provide a new way to optimize icebreaking strategies, improve icebreaking efficiency, and reduce noise pollution.

[0053] See also Figures 1 to 15 :

[0054] The first embodiment is a method for analyzing internal stress of ice blocks under the action of an underwater laser spot array, comprising the following steps:

[0055] Step 1, establishment and verification of hydrodynamic module:

[0056] In order to accurately obtain the water flow force acting on the ice, this application constructs a water tank numerical model of the interaction between water flow and fixed ice. The shear stress transport k-ωSST turbulence model is used to simulate the turbulent characteristics of the fluid, the fluid volume method (VOF) is used to capture the free interface, and the finite volume method (FVM) is used for spatial discretization. The coupled calculation of velocity and pressure is realized by the PIMPLE algorithm (i.e., the PISO-SIMPLE combined algorithm). Subsequently, the simulation results are compared and analyzed with the actual measured flow velocity data to verify the accuracy and reliability of the numerical calculation method. The control equation is as follows:

[0057] Continuity equation:

[0058]

[0059] Momentum conservation equation:

[0060]

[0061] Where: ρ is the fluid density, t is the time, U is the velocity vector, p is the pressure, μ is the fluid dynamic viscosity, σ is the surface tension, κ is the mean curvature of the free interface, and n is the free surface normal vector.

[0062] Step 2, obtaining water flow force:

[0063] The water flow force involves the drag force (the force generated in the direction of the water flow) and the lift force (the force generated perpendicular to the direction of the water flow) acting on the ice cube, and the calculation method is:

[0064] F w =C r ρA w U 2 (3)

[0065] Where: F w A is the water flow force on the fixed ice. w is the projected area of ​​the headstream of the fixed ice.

[0066] First, the velocity field, pressure field and stress tensor of the fluid must be calculated, and then the water flow force is calculated by equation (3), and compared with the water flow force under ice under different water flow conditions obtained in the flume physical model experiment. The measured data is used as the water flow force applied to the solid mechanics model for stress analysis of different ice blocks under static pressure and pulse loads;

[0067] In fluid mechanics, the water flow force is obtained by decoupling the momentum equation and the continuity equation. The PISO algorithm used is an improvement on the SIMPLE algorithm. Compared with the SIMPLE algorithm, the PISO algorithm introduces an additional correction step in the calculation process, which significantly improves the convergence efficiency.

[0068] Step 3, establishment of ice solid mechanics module:

[0069] The governing equation is based on the mechanics of continuous media, using the law of conservation of momentum and combining the elastic-plastic constitutive relation of the material to describe the relationship between stress and strain. At the same time, the relationship between strain and displacement is defined by geometric equations. In terms of discretization, the finite element method (FEM) is used, and tetrahedral units are used for division in space, and the implicit time integration method is used in time to ensure the stability of the calculation process. The boundary conditions considered include static pressure loads and pulse loads, while the mechanical boundaries are set as fixed constraints. The model is verified by the maximum stress at the position of the mechanical load pressure head. In the process of constructing the solid mechanics model of ice, it is first necessary to obtain the geometric dimensions of the ice, including the overall length, width, height, and laser point distribution parameters of the internal structure (such as the number, depth, and spacing of holes). In addition, it is necessary to determine the physical parameters (such as density, specific heat capacity, etc.) and mechanical parameters (such as elastic modulus, Poisson's ratio, yield strength, plastic strain, etc.) of polar ice, and to clarify the mechanical loads applied to the ice;

[0070] In this application, a nonlinear elastic-plastic solid mechanics model of ice cubes is constructed based on the obtained ice cube size and material parameters. Before cracks are generated under pressure, the ice cube material is in a linear elastic stage and satisfies Hooke's law; when the stress reaches the yield value, the material enters the plastic stage. In order to construct an elastic-plastic model, plastic nodes are added to the linear elastic material to describe the plastic deformation behavior. The equilibrium equation of solid mechanics is established based on Newton's second law. In transient analysis, the time effect cannot be ignored, so the volume force, surface stress, inertial force and damping force must reach equilibrium at the same time. Therefore, the dynamic equilibrium equation of continuous medium mechanics is as follows:

[0071]

[0072] Where: s is the mass per unit volume, u is the displacement, is the acceleration, d a is the damping coefficient, is the divergence of the stress tensor, i.e., the surface stress, F v is the volume force. Before reaching the initial yield stress, the elastoplastic material behaves in an elastic manner. The equivalent stress in the plastic stage is determined using the Von Mises yield criterion, and the yield condition of the material is:

[0073] F(σ)=σ s -σ ys (5)

[0074] Where: s is the equivalent stress, σ ys is the initial yield stress, and F(σ) is the yield function.

[0075] Step 4, fitting the static pressure load and pulse load equations:

[0076] Based on the experimental data of laser-assisted static pressure load and pulse load icebreaking physical model, the mathematical expressions of static pressure load and pulse load changing with time are fitted by the combined algorithm of quasi-Newton method (BFGS) and general global optimization method:

[0077] The static pressure load P(t) generated by the jack is:

[0078]

[0079] Where: t is time.

[0080] Pulse load I(t):

[0081]

[0082] When the ice is subjected to external loads, the actual force on the surface element acts on the current area da along the normal direction. Therefore, the pressure load type should be specified as surface load F. s :

[0083]

[0084] Where: f is the static pressure load P(t) or pulse load I(t), A s is the total area and a is the unit area.

[0085] Step 5, coupling calculation and verification of the hydrodynamic module and the ice solid mechanics module:

[0086] Referring to the laser array parameters set in the physical model experiment, the water flow force obtained in S2 and the static pressure load expression fitted in S4 are applied to the ice solid mechanics model established in S3, and stress measurement points are set corresponding to the jack head area in the physical experiment. After calculation, the simulation results are compared with the actual measured values ​​of the physical model to ensure that the relative error is low, so as to prove that the established ice solid mechanics model can better reflect the stress state of the ice when it is actually subjected to force;

[0087] Step 6: Selection and optimization of initial laser array point distribution parameters:

[0088] The initial parameters of the laser array point distribution are set, including the number of holes, hole depth and spacing. Based on the physical model experiment of laser-assisted pulse load icebreaking, the initial parameters of the laser array point distribution are established, and the single factor sensitivity analysis of the laser array point distribution parameters is performed through solid mechanics numerical simulation. Based on the Macquart method, the relationship equation between the maximum stress inside the ice block and different laser point distribution parameters is constructed, and the initial laser array point distribution parameters are optimized.

[0089] For example, based on the laser-assisted static pressure load icebreaking physical model experiment, cylindrical holes are set on the ice to simulate the local damage caused by the laser on the ice. The initial parameters are 4*4 points, 150mm depth, 24mm spacing, and 8mm hole diameter.

[0090] After single factor sensitivity analysis of laser point distribution parameters, the relationship equation between different laser point distribution parameters and the maximum stress inside the ice block was fitted by using the combined algorithm of the quasi-Newton method (BFGS) and the general global optimization method:

[0091] The fitting formula between the number of holes x1 and the maximum stress y inside the ice block is:

[0092]

[0093] The fitting formula between the hole depth x2 and the maximum stress y inside the ice block is:

[0094]

[0095] The fitting formula between the hole spacing x3 and the maximum stress y inside the ice block is:

[0096]

[0097] The root mean square error (RMSE) of the above fitting formula is 7.28×10 -6 ~2.24×10 -5 The coefficient of certainty (DC) is 0.99, indicating that the model has a very high certainty. According to the fitting relationship between the number, spacing and depth of laser holes and the maximum stress inside the ice, the maximum stress can be calculated by the given laser array parameters in the design stage of the laser array assisted pulse load icebreaking experiment, so as to optimize the array parameters to achieve the best icebreaking effect.

[0098] Step 7, comparison and selection of load types:

[0099] Apply the static pressure load equation and pulse load equation in step 4 to the ice model with the same distribution parameters, and compare the maximum stress value generated inside the ice and the time required to reach the stress value. Through comparative analysis, select the load type with better ice-breaking efficiency;

[0100] Step 8: Calculate the distribution of internal stress of ice cubes in time and space under the action of pulse load and water flow force:

[0101] Based on the relationship equation between different laser point distribution parameters and the maximum stress inside the ice block fitted in step 6, the optimal laser array point distribution parameters are selected according to the actual situation. Then, they are combined with the dominant load in step 7 and the water flow force obtained in step 2 to achieve the best mechanical effect in the ice-breaking process and improve the ice-breaking efficiency.

[0102] The second embodiment is a system for analyzing internal stress of ice blocks under the action of an underwater laser spot array, which is used to implement the method of the first embodiment. The system includes:

[0103] Hydrodynamics module: Based on the shear stress transport k-ωSST turbulence model, a numerical model of a water tank for the interaction between water flow and fixed ice cubes is established. The free interface is captured using the volume of fluid method (VOF), and the velocity and pressure coupling is achieved through the PIMPLE algorithm. The water flow forces including drag and lift are obtained. By calculating the fluid velocity field, pressure field and stress tensor, the total water flow force is obtained by integrating the surface force distribution of the ice cube, and the accuracy of the model is verified by comparing it with the physical experimental data. The control equation is as follows:

[0104] Continuity equation:

[0105]

[0106] Momentum conservation equation:

[0107]

[0108] Where: ρ is the fluid density, t is the time, U is the velocity vector, p is the pressure, μ is the fluid dynamic viscosity, σ is the surface tension, κ is the mean curvature of the free interface, and n is the free surface normal vector.

[0109] The water flow force involves the drag force (the force generated in the direction of the water flow) and the lift force (the force generated perpendicular to the direction of the water flow) acting on the ice cube, and the calculation method is:

[0110] F w =C r ρA w U 2 (3)

[0111] Where: F w A is the water flow force on the fixed ice. w is the projected area of ​​the headstream of the fixed ice.

[0112] Ice solid mechanics module: Based on continuum mechanics, the momentum conservation equation and elastoplastic constitutive relations are used to describe the stress and strain of ice. The boundary conditions are static pressure and pulse load, and the mechanical boundary is set as a fixed constraint to verify the maximum stress at the indenter position. When the model is established, the geometric dimensions of the ice, the laser point distribution parameters, and the physical and mechanical parameters of the ice are obtained, and the analysis is combined with the applied load. The dynamic equilibrium equation of continuum mechanics is as follows:

[0113]

[0114] Where: s is the mass per unit volume, u is the displacement, is the acceleration, d a is the damping coefficient, is the divergence of the stress tensor, i.e., the surface stress, F v is the volume force. Before reaching the initial yield stress, the elastoplastic material behaves in an elastic manner. The equivalent stress in the plastic stage is determined using the Von Mises yield criterion, and the yield condition of the material is:

[0115] F(σ)=σ s -σ ys (5)

[0116] Where: s is the equivalent stress, σ ys is the initial yield stress, and F(σ) is the yield function.

[0117] Fitting static pressure load and pulse load equation module: Based on the experimental data of laser-assisted static pressure load and pulse load icebreaking physical model, the mathematical expressions of static pressure load and pulse load changing with time are fitted by the combined algorithm of quasi-Newton method (BFGS) and general global optimization method as follows:

[0118] The static pressure load P(t) generated by the jack is:

[0119]

[0120] Where: t is time.

[0121] Pulse load I(t):

[0122]

[0123] When the ice is subjected to external loads, the actual force on the surface element is applied to the current area da along the normal direction. Therefore, the pressure load type should be specified as a surface load F. s :

[0124]

[0125] Where: f is the static pressure load P(t) or pulse load I(t), A s is the total area and a is the unit area.

[0126] Coupling calculation and verification module of hydrodynamic model and ice solid mechanics model: referring to the laser array parameters set in the physical model experiment, the water flow force obtained in the hydrodynamic module and the static pressure load expression fitted in the fitting static pressure load and pulse load equation modules are applied to the model established in the ice solid mechanics module, and stress measurement points are set in the jack head area corresponding to the physical experiment. After calculation, the simulation results are compared with the actual measured values ​​of the physical model to ensure that the relative error is low, so as to prove that the established ice solid mechanics model can better reflect the stress state of the ice when it is actually subjected to force.

[0127] Selection and optimization module of initial laser array point distribution parameters: According to the laser-assisted pulse load icebreaking experiment, the initial laser array point distribution parameters (number of holes, hole depth and hole spacing) are set. Through solid mechanics numerical simulation, single factor sensitivity analysis is performed, and the relationship between laser point distribution parameters and maximum stress of ice blocks is fitted based on the Macquart method, and the initial parameter settings are optimized to improve the icebreaking effect. The fitting formula is as follows:

[0128] The fitting formula between the number of holes x1 and the maximum stress y inside the ice block is:

[0129]

[0130] The fitting formula between the hole depth x2 and the maximum stress y inside the ice block is:

[0131]

[0132] The fitting formula between the hole spacing x3 and the maximum stress y inside the ice block is:

[0133]

[0134] Load type comparison and selection module: The static pressure load equation and pulse load equation in the static pressure load and pulse load equation fitting module are applied to the ice block model with the same distribution parameters, and the maximum stress value generated inside the ice block and the time required to reach the stress are compared. The ice-breaking effect of the two load types is evaluated, and the load type with better ice-breaking efficiency is selected.

[0135] Module for calculating the distribution of internal stress of ice cubes in time and space under the action of pulse load and water flow force: Based on the selection of initial laser array point distribution parameters and the relationship equation between the laser point distribution parameters fitted in the optimization module and the maximum stress inside the ice cube, the optimal laser array point distribution parameters are selected according to the actual situation. Combined with the dominant load in the load type comparison selection module and the water flow force obtained in the hydrodynamic module, the best ice-breaking mechanical effect is achieved.

[0136] The present invention has significant technical advantages and application effects, which are mainly reflected in the following aspects:

[0137] (1) Establish a coupling model between hydrodynamics and ice solid mechanics

[0138] The present invention constructs a numerical model of the water tank to obtain the water flow force, and at the same time, establishes a solid mechanics model of ice based on the physical properties and mechanical parameters of polar ice. Based on the physical experiment of laser-assisted icebreaking, the present invention fits the external force equations of static pressure load and pulse load. By applying the fitted static pressure load equation and water flow force to the solid mechanics model of ice, it is possible to accurately simulate the stress state caused by various external forces that ice is subjected to under the local destruction of the laser array.

[0139] (2) Select and optimize laser point placement parameters

[0140] The present invention calculates the influence of the laser array on the maximum stress inside the ice cube under different point number, depth and spacing conditions by performing single factor sensitivity analysis, and accordingly fits an equation reflecting the relationship between different point parameters and the maximum stress value. This equation can help determine the optimal point parameters of the laser array in the early stage of scheme design, thereby realizing the optimal design of the icebreaking system and ensuring the optimization of icebreaking efficiency. This advantage makes the present invention have higher practical value in practical applications.

[0141] (3) Significantly improve underwater icebreaking efficiency

[0142] The present invention uses the relationship equation between laser point distribution parameters and the maximum stress inside the ice to screen out the best point distribution parameters, and combines the combined effect of the dominant load and water flow force to achieve the best ice-breaking effect. Compared with traditional mechanical ice-breaking methods, this invention is expected to significantly improve ice-breaking efficiency while significantly reducing noise.

[0143] Innovation and application prospects: The innovation of this invention lies in the use of a laser dot array to generate thermal effects or structural weakening points, combined with mechanical icebreaking to achieve efficient collaborative operations. This technology can adapt to thick ice, heterogeneous ice layers and complex polar environments, and optimize parameter design through numerical simulation. In the fields of polar waterway development, energy exploration, scientific research and environmental protection, military rescue, etc., this technology shows broad application prospects. It can not only improve icebreaking efficiency and reduce operating costs, but also reduce damage to the environment. In the future, this technology is expected to integrate intelligent technology to promote the realization of unmanned polar operations and provide important support for polar resource development and international cooperation.

[0144] The above embodiment first constructs a hydrodynamic model and verifies it to obtain the stress of ice cubes under the action of water flow and obtain water flow force data; secondly, based on the physical and mechanical parameters of polar ice, a solid mechanical model of ice cubes is established to accurately describe the force response of ice cubes. Then, the external force equations of static pressure load and pulse load are fitted through the laser-assisted icebreaking physical experiment data, and the initial laser point distribution parameters are set. Through single-factor sensitivity analysis, the relationship equation between the laser point distribution parameters and the maximum stress inside the ice cube is fitted. The fitted static pressure load curve is applied to the solid mechanical model of ice cubes, and the simulation results are calculated and compared with the physical experimental data to verify the accuracy of the model. The static pressure load and pulse load are further applied to the ice cube model with the same point distribution parameters, and the maximum stress values ​​and action times generated by the two loads are compared to select the load type with better icebreaking efficiency. Finally, the optimal laser point distribution parameters are selected through the relationship equation between the point distribution parameters and the maximum stress, and the icebreaking effect is optimized by combining the advantageous load and water flow force, thereby improving the overall icebreaking efficiency.

[0145] The following is an example of a specific implementation case:

[0146] This implementation case first constructed a numerical model of the wave flume to obtain the water flow force. Subsequently, a static pressure load icebreaking experiment was carried out based on the laser point distribution technology. According to the obtained physical and mechanical parameters of the ice, a three-dimensional model of a 200×200×200 mm cube ice block with the same size as the ice sample in the experiment was constructed. Based on the physical model experimental data, the data of static pressure load and pulse load were obtained, and the equations of these two loads were fitted. After setting the initial laser array point distribution parameters, the relationship equation between different laser point distribution parameters and the maximum stress inside the ice block was fitted through single-factor sensitivity analysis. The fitted static pressure load curve was applied to the solid mechanics model of the ice block, and the calculation simulation results were compared with the physical experimental data. The error was controlled within 9%, thereby verifying the accuracy of the model. Static pressure load and pulse load were applied to the ice block model with the same point distribution parameters. It was found that the pulse load took a shorter time to produce the same maximum stress inside the ice block, so the pulse load was selected as the main load. Finally, the optimal laser point placement parameters were determined through the relationship equation between the point placement parameters and the maximum stress of ice.

[0147] The specific implementation steps of the method described in this implementation include the following steps:

[0148] Step 1, establishment and verification of hydrodynamic model:

[0149] The numerical model of the flume for the interaction between water flow and fixed ice is established based on the volume of fluid method (VOF) and the finite volume method (FVM). Figure 2 As shown, by adjusting different water flow parameters, such as flow velocity, wave height and period, different hydrodynamic environments are simulated. The ice bottom measurement point position 3 is located at the bottom of the ice row 2; the free surface 1 is located on both sides of the ice row 2.

[0150] Step 2, obtaining water flow force:

[0151] An ice cube geometry model is set up in a water tank, and multiple pressure measuring points are arranged at different positions to measure the water flow force on the surface of the model for the subsequent step 8, where the drag force and the corresponding flow velocity are as follows: Figure 3 shown.

[0152] Step 3, establishment of ice solid mechanics model:

[0153] Obtain the physical and mechanical parameters of polar ice required for simulation in this case. The density of ice is selected as 930.00 kg / m 3 , Young's modulus is selected as 2.00 GPa, Poisson's ratio is selected as 0.30, and initial yield stress is selected as 2.12 MPa. Then, based on the laser point distribution assisted static pressure load ice breaking experiment, an elastoplastic solid mechanics model of ice blocks with the same size of 200×200×200 mm as the ice sample in the experiment is established, such as Figure 4As shown, the number, depth and spacing of the holes in the figure are not unique and can be modified according to simulation needs.

[0154] Step 4, fitting the static pressure load and pulse load equations:

[0155] Based on the experimental data of laser-assisted static pressure load and pulse load icebreaking physical model, the mathematical expressions of static pressure load and pulse load changing with time are fitted by the combined algorithm of quasi-Newton method (BFGS) and general global optimization method:

[0156] The static pressure load P(t) generated by the jack is:

[0157]

[0158] Where: t is time.

[0159] Pulse load I(t):

[0160]

[0161] The function graph is Figure 5 and Figure 6 As shown, Figure 6 The image in the middle is the merged image of the three curve segments.

[0162] Step 5, coupling calculation and verification of the hydrodynamic module and the ice solid mechanics module:

[0163] Referring to the laser array parameters set in the physical model experiment, the static pressure load curve fitted in step 4 is applied to the ice solid mechanics model established in step 3, and a stress probe is set corresponding to the jack pressure head area in the physical experiment. After calculation, the simulated pressure-displacement curve of the pressure head area is compared with the physical measured value. The verification result is as follows Figure 7 As shown, the relative error does not exceed 9.00%, indicating that the model can better reflect the stress state of ice when it is compressed.

[0164] Step 6, selection and optimization of initial laser array parameters:

[0165] Based on the physical model experiment, the hole diameter is uniformly set to 8mm. The initial laser array point distribution parameters are 4*4, 150mm in depth, and 24mm in spacing.

[0166] In the optimization of laser point placement parameters, the variation curve of the maximum stress inside the ice cube with different laser point placement parameters was obtained through single factor sensitivity analysis of laser point placement parameters, such as Figures 8 to 10 , and the stress distribution of the ice block cross section under the maximum stress condition in different parameter calculations, such as Figures 11 to 13 Based on the Macquart method, the relationship equation between different laser point distribution parameters and the maximum stress inside the ice cube is fitted as follows:

[0167] The fitting formula between the number of holes x1 and the maximum stress y inside the ice block is:

[0168]

[0169] The fitting formula between the hole depth x2 and the maximum stress y inside the ice block is:

[0170]

[0171] The fitting formula between the hole spacing x3 and the maximum stress y inside the ice block is:

[0172]

[0173] Step 7, comparison and selection of load types:

[0174] Based on the working conditions of 2*2 holes, 200mm hole depth, and 6.67mm hole spacing, the static pressure load equation and pulse load equation fitted in step 4 were applied to the ice cube to obtain the stress distribution under different loads, as shown in the following figure: Fig.14 and Fig.15 Through comparative analysis, it is found that the pulse load takes a shorter time to produce the same maximum stress value in ice and is more efficient, so the pulse load is selected as the dominant load.

[0175] Step 8: Calculate the distribution of internal stress of ice cubes in time and space under the action of pulse load and water flow force:

[0176] Based on the relationship equation between different laser point distribution parameters and the maximum stress inside the ice block fitted in step 6, the optimal laser point distribution parameters are selected as: number of holes 3*3, hole depth 80mm, hole spacing 80mm. Subsequently, it can be combined with the pulse load selected in step 7 and the water flow force obtained in step 2 to simulate the ice breaking process with the best mechanical effect.

[0177] A third embodiment is a computer program product, comprising a computer program, which, when executed by a processor, implements the above-mentioned method for analyzing the internal stress of ice blocks under the action of the underwater laser spot array.

[0178] The fourth embodiment is an information data processing terminal for an analysis method of internal stress of ice blocks under the action of an underwater laser spot array.

[0179] A fifth embodiment is a computer-readable storage medium, comprising instructions, which, when executed on a computer, enables the computer to execute the above-mentioned method for analyzing the internal stress of ice blocks under the action of the underwater laser spot array.

[0180] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When the use is implemented in whole or in part in the form of a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable system. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL) or wireless (e.g., infrared, wireless, microwave, etc.) mode) to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk SolidState Disk (SSD)), etc.

[0181] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for analyzing internal stress of ice blocks under the action of an underwater laser spot array, characterized in that: include: S1. Establishment and verification of hydrodynamic module; S2, obtain water flow force; S3, establish ice solid mechanics module; S4, fitting static pressure load equation and pulse load equation; S5. Coupling calculation and verification of hydrodynamic module and ice solid mechanics module; Referring to the laser array parameters set in the physical model experiment, the water flow force obtained in S2 and the static pressure load expression fitted in S4 are applied to the ice solid mechanics model, and stress measurement points are set corresponding to the jack head area in the physical experiment. After calculation, the simulation results are compared with the measured values ​​of the physical model to ensure that the relative error meets the requirements; S6, selection and optimization of initial laser array point distribution parameters; S7. Comparison and selection of load types; S8. Calculate the distribution of internal stress of ice cubes in time and space under the action of pulse load and water flow force.

2. The method for analyzing internal stress of ice blocks under the action of an underwater laser spot array according to claim 1, characterized in that: S1 is specifically as follows: In order to obtain the water flow force acting on the ice, a numerical model of a water tank for the interaction between water flow and fixed ice is established, the shear stress transport k-ωSST turbulence model is adopted, the fluid volume method is used to capture the free interface, the finite volume method is used for spatial discretization, and the coupling of velocity and pressure is realized through the PIMPLE algorithm. The simulation results are compared with the measured flow velocity data to verify the accuracy and reliability of the numerical calculation method.

3. The method for analyzing internal stress of ice blocks under the action of an underwater laser spot array according to claim 2, characterized in that: S2 is specifically: the water flow force includes the drag force and lift acting on the ice cube; first, the velocity field, pressure field and stress tensor of the fluid are calculated, and then the total water flow force is obtained by integrating over the surface of the ice cube, and compared and verified with the under-ice water flow force under different water flow conditions obtained in the water tank physical model experiment. The measured data is used as the water flow force applied to the solid mechanics model and is applied to the stress analysis of different ice cubes under static pressure and pulse loads.

4. The method for analyzing internal stress of ice blocks under the action of an underwater laser spot array according to claim 1, characterized in that: S3 is specifically: Obtaining the geometric dimensions of the ice block, including the overall length, width, height, and laser point distribution parameters of the internal structure, wherein the laser point distribution parameters include the number, depth, and spacing of holes; Determine the physical and mechanical parameters of polar ice and clarify the mechanical loads applied to the ice; the physical parameters include density and specific heat capacity; the mechanical parameters include elastic modulus, Poisson's ratio, yield strength, and plastic strain.

5. The method for analyzing internal stress of ice blocks under the action of an underwater laser spot array according to claim 1, characterized in that: S4 is specifically as follows: Based on the experimental data of the laser-assisted static pressure load and pulse load icebreaking physical model, the mathematical expressions of the static pressure load and pulse load changing with time are fitted through the combined algorithm of the quasi-Newton method and the general global optimization method.

6. The method for analyzing internal stress of ice blocks under the action of an underwater laser spot array according to claim 1, characterized in that: S6 is specifically as follows: Based on the laser-assisted pulse load icebreaking physical model experiment, the initial laser array distribution parameters are set, and through solid mechanics numerical simulation, the single factor sensitivity analysis of the laser array distribution parameters is carried out. Based on the Macquart method, the relationship equation between different laser distribution parameters and the maximum stress inside the ice is fitted, and the initial laser array distribution parameter settings are optimized.

7. The method for analyzing internal stress of ice blocks under the action of an underwater laser spot array according to claim 1, characterized in that: S7 is specifically as follows: applying the static pressure load equation and the pulse load equation to the ice block model with the same distribution parameters respectively, comparing the maximum stress value generated inside the ice block and the time required to reach the stress value, and selecting the load type with better ice breaking efficiency through comparative analysis.

8. The method for analyzing internal stress of ice blocks under the action of an underwater laser spot array according to claim 6, characterized in that: S8 is specifically as follows: based on the relationship equation between different laser point distribution parameters and the maximum stress inside the ice, the optimal laser array point distribution parameters are selected according to the actual situation, and then combined with the load with better icebreaking efficiency selected in S7 and the water flow force obtained in S2 to achieve the best mechanical effect in the icebreaking process and improve the icebreaking efficiency.

9. An ice block internal stress analysis system under the action of an underwater laser spot array, characterized in that: include: Hydrodynamics module: Based on the shear stress transport k-ωSST turbulence model, a numerical model of a water tank for the interaction between water flow and fixed ice cubes is established. The free interface is captured using the fluid volume method, and the velocity and pressure coupling is achieved through the PIMPLE algorithm. The water flow force including drag force and lift is obtained. The total water flow force is obtained by calculating the fluid velocity field, pressure field and stress tensor, integrating the ice surface force distribution, and comparing it with the physical experimental data to verify the accuracy of the model; Ice solid mechanics module: Based on continuum mechanics, the momentum conservation equation and elastic-plastic constitutive relation are used to describe the stress and strain of ice. The boundary conditions are static pressure and pulse load, and the mechanical boundary is set as a fixed constraint to verify the maximum stress at the pressure head position. When the model is established, the geometric dimensions of the ice, the laser point distribution parameters, and the physical and mechanical parameters of the ice are obtained, and the analysis is carried out in combination with the applied load; Fitting static pressure load and pulse load equation module: Based on the experimental data of laser-assisted static pressure load and pulse load icebreaking physical model, the mathematical expressions of static pressure load and pulse load changing with time are fitted through the combined algorithm of quasi-Newton method and general global optimization method; Coupling calculation and verification module of hydrodynamic model and ice solid mechanics model: referring to the laser array parameters set in the physical model experiment, the water flow force obtained in the hydrodynamic module and the static pressure load expression fitted in the static pressure load fitting and pulse load equation modules are applied to the model established in the ice solid mechanics module, and stress measurement points are set in the jack head area in the physical experiment. After calculation, the simulation results are compared with the measured values ​​of the physical model to ensure that the relative error meets the requirements; Selection and optimization module of initial laser array point distribution parameters: According to the laser-assisted pulse load icebreaking experiment, the initial laser array point distribution parameters are set, and single-factor sensitivity analysis is performed through solid mechanics numerical simulation. The relationship between the laser point distribution parameters and the maximum stress of ice blocks is fitted based on the Macquart method, and the initial parameter settings are optimized to improve the icebreaking effect; Load type comparison and selection module: The static pressure load equation and the pulse load equation are applied to the ice block model with the same distribution parameters, and the maximum stress value generated inside the ice block and the time required to reach the stress are compared to evaluate the ice-breaking effect of the two load types and select the load type with better ice-breaking efficiency; Module for calculating the distribution of internal stress of ice cubes in time and space under the action of pulse loads and water flow forces: Based on the selection of initial laser array point distribution parameters and the relationship equation between the laser point distribution parameters fitted in the optimization module and the maximum internal stress of the ice cube, the optimal laser array point distribution parameters are selected according to the actual situation, and combined with the dominant load in the load type comparison selection module and the water flow force obtained in the hydrodynamic module to achieve the best icebreaking mechanical effect.

10. A computer-readable storage medium, comprising instructions, which, when executed on a computer, enables the computer to execute the method for analyzing internal stress of ice blocks under the action of an underwater laser spot array as described in any one of claims 1 to 8.

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