Method and system for simulating freeze-thaw damage of concrete

Abstract

The invention discloses a concrete freeze-thaw failure simulation method and system, and relates to the technical field of material failure prediction and mechanical numerical simulation. Comprising the following steps: based on a conventional state-based near-field dynamic model, defining mass point coordinates, endowing concrete material attributes, creating family members of mass points and generating keys; setting a broken'key 'based on the open porosity rho; a freeze-thaw force state is applied to mass points at the two ends of the fractured'key ', which indicates that the pore or crack surface is subjected to the freeze-thaw pressure effect; freeze-thaw pressure is applied to the fractured key, and dynamic capture of new cracks is achieved. According to the method, the freeze-thaw force state is directly applied to the mass points at the two ends of the fractured'key ', the mesoscale simulation of the concrete freeze-thaw process is realized without constructing a complex temperature field model, the calculation efficiency is effectively improved, and a remarkable effect is achieved in the aspect of simulating freeze-thaw damage and crack propagation.

Description

Technical Field

[0001] The invention relates to the technical field of material failure prediction and mechanical numerical simulation, and in particular to a concrete freeze-thaw damage simulation method and system. Background Art

[0002] Freeze-thaw damage is undoubtedly an important factor that cannot be ignored in the durability of concrete in cold regions. This damage often causes severe peeling of the concrete surface, which in turn leads to a significant reduction in the thickness of the steel bar protection layer, or even complete exposure, which seriously threatens the safety and stability of the structure. At the same time, fine and complex cracks will also appear inside the concrete due to freeze-thaw action. These cracks not only weaken the rigidity of the concrete, but also greatly reduce its overall strength.

[0003] When trying to simulate such crack growth problems through methods based on continuum mechanics theory, researchers often encounter severe challenges, especially mesh dependency, which greatly reduces the accuracy and reliability of simulation results. To address this problem, peridynamics, as a non-local theory, has made significant progress in the field of crack simulation, providing new perspectives and tools for simulating crack growth in materials such as concrete.

[0004] However, it is worth noting that the root cause of concrete freeze-thaw damage often lies in the water in its internal pores. There is a huge order of magnitude difference between the size of these pores and the overall size of the concrete specimen, which requires that the influence of this tiny pore structure on the overall performance must be considered when performing refined modeling. However, this refined modeling process will undoubtedly greatly increase the complexity and resource consumption of the calculation, making it challenging in practical applications. Therefore, how to reduce the consumption of computing resources while ensuring the simulation accuracy has become a key issue that needs to be urgently solved in the current field of concrete freeze-thaw damage simulation. Summary of the invention

[0005] The purpose of the present invention is to propose a concrete freeze-thaw damage simulation method and system, establish the relationship between the peridynamic freeze-thaw force state and the freeze-thaw pressure, realize the dynamic capture of concrete freeze-thaw cracks, and improve the calculation efficiency.

[0006] According to a first aspect of an embodiment of the present disclosure, a method for simulating freeze-thaw damage of concrete is provided, comprising the following steps:

[0007] Based on the conventional state-based peridynamic model, the coordinates of the particles are defined and the concrete material properties are assigned, the family members of the particles are created and the "bonds" are generated;

[0008] Based on the open porosity ρ, the “bonds” for the fracture are set;

[0009] The freeze-thaw stress state is applied to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure;

[0010] Apply freeze-thaw pressure to the broken "bonds" to dynamically capture the new cracks.

[0011] In one embodiment, the conventional state-based peridynamic equation of motion is as follows:

[0012]

[0013] Where ρ is the peridynamic unit density, is the acceleration of the peridynamic unit, H(x) is the near-field integration domain, T is the force state between the peridynamic units, dV is the volume of the peridynamic unit, and b is the volume force;

[0014] The force state in the conventional state-based peridynamic equation is expressed as:

[0015]

[0016] Where K and G represent the bulk modulus and shear modulus in classical mechanics, ν is Poisson's ratio, ω is the influence function, x is the initial distance between peridynamic units, m is the weighted volume in peridynamics, m = (ωx) x, θ is the volume expansion term, e d is the deflected part of the elongation,

[0017] In peridynamics, damage is defined as follows:

[0018]

[0019] Among them, φ(x) represents the damage degree of the peridynamic unit, and d(ξ) represents the breaking of the "bond" between the two peridynamic units; when d(ξ) = 0, it means that the "bond" is intact; when d(ξ) = 1, it means that the "bond" is broken.

[0020] In one embodiment, the breaking criterion of the "bond" adopts the energy density criterion. When the energy density of the "bond" is greater than the critical energy density, the "bond" is broken, that is, d(ξ)=1. The critical energy density is expressed as:

[0021]

[0022] Among them, G c is the critical energy release rate, and h is the plate thickness for two-dimensional problems.

[0023] In one embodiment, let the number of all "bonds" in the model be N, and the number of "bonds" that are broken in advance be n, satisfying Randomize the "bonds" that are pre-set to break.

[0024] In one embodiment, freeze-thaw stress states are applied to the particles at both ends of the broken "bond", specifically: the freeze-thaw pressure on the crack surface is defined as P, and the freeze-thaw stress state applied between the peridynamic particles is defined as T ice , this force state does not disappear with the destruction of the bond between the particles, and the magnitude of this force state is related to the length of the "bond":

[0025] T ice =t ice ·(1-ξ / δ)

[0026] Among them, ξ is the length of the "key" and δ is the sight distance;

[0027] The freeze-thaw pressure P and freeze-thaw state T ice The relationship is:

[0028]

[0029] In one embodiment, the freeze-thaw state is expressed as:

[0030]

[0031] In one of the embodiments, newly formed cracks are captured dynamically. Specifically, when a new "bond" breaks, it indicates that the crack is expanding. At this time, pore water will enter the crack and generate new freeze-thaw pressure. Therefore, the present invention applies freeze-thaw force to the particles at both ends of each broken "bond", thereby capturing the crack tip and simulating the migration of pore water.

[0032] According to a second aspect of an embodiment of the present disclosure, a concrete freeze-thaw damage simulation system is provided, comprising:

[0033] The "bond" generation module defines the coordinates of the particles and assigns concrete material properties based on the conventional state-based peridynamic model, creates family members of the particles and generates "bonds";

[0034] The initial damage setting module sets the fracture “key” based on the open porosity ρ;

[0035] The application module applies freeze-thaw stress state to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure;

[0036] The capture module applies freeze-thaw pressure to the broken "bonds" to achieve dynamic capture of new cracks.

[0037] According to a third aspect of an embodiment of the present disclosure, an electronic device is provided, including a memory, a processor, and a computer program stored and running on the memory, wherein the processor implements the method for simulating freeze-thaw damage of concrete when executing the program.

[0038] According to a fourth aspect of the embodiments of the present disclosure, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the method for simulating freeze-thaw damage of concrete is implemented.

[0039] Compared with the prior art, the above technical solution adopted by the present invention has the following advantages: the present invention directly applies freeze-thaw force states to the particles at both ends of the broken "bond", without the need to construct a complex temperature field model, thereby realizing the mesoscopic scale simulation of the freeze-thaw process of concrete, effectively improving the calculation efficiency, and achieving remarkable results in simulating freeze-thaw damage and crack propagation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings in the specification, which constitute a part of the present application, are used to provide further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0041] Figure 1 It is a flow chart of the concrete freeze-thaw damage simulation method of the present invention;

[0042] Figure 2 It is a schematic diagram of freeze-thaw pressure and freeze-thaw force state of the present invention;

[0043] Figure 3 is a graph showing the results of a freeze-thaw surface peeling test of concrete according to an embodiment of the present invention;

[0044] Figure 4 is a graph showing the freeze-thaw crack growth test results of concrete according to an embodiment of the present invention;

[0045] Figure 5 4 is a diagram of concrete freeze-thaw simulation results according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0047] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0048] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0049] It should be noted that the flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the methods and systems according to various embodiments of the present disclosure. It should be noted that each box in the flowchart or block diagram can represent a module, a program segment, or a part of a code, and the module, program segment, or a part of a code may include one or more executable instructions for implementing the logical functions specified in each embodiment. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the flowchart and / or block diagram, and the combination of boxes in the flowchart and / or block diagram can be implemented using a dedicated hardware-based system that performs a specified function or operation, or can be implemented using a combination of dedicated hardware and computer instructions.

[0050] This embodiment is explained based on two-dimensional concrete, with a size of 100mm×100mm, a concrete grade of C40, and a total of 200×200 particles. The line of sight of each particle δ=3Δx=1.5mm, and the model does not set boundary conditions, and the boundaries can move freely. The open porosity measured in the experiment is 1.68%, and the freeze-thaw pressure P obtained by the finite element method is 58.3MPa. The concrete was simulated for 120 freeze-thaw cycles and compared with the test results. The test used a TDR-15D concrete rapid freeze-thaw tester with a temperature range of (-18±2)℃~(18±2)℃. Before the experiment began, the concrete was first soaked in clean water for 4 days to ensure that the water fully penetrated the concrete. The freeze-thaw tester was then started, and the freeze-thaw cycle test was performed according to the pre-set number of cycles and temperature.

[0051] Embodiment 1:

[0052] like Figure 1 As shown, this embodiment provides a method for simulating freeze-thaw damage of concrete, comprising the following steps:

[0053] Step 1: Based on the conventional state-based peridynamic model, define the coordinates of the particles and assign concrete material properties, create family members of the particles and generate "bonds";

[0054] Specifically, the conventional state-based peridynamic equation of motion is as follows:

[0055]

[0056] Where ρ is the peridynamic unit density, is the acceleration of the peridynamic unit, H(x) is the near-field integration domain, T is the force state between the peridynamic units, dV is the volume of the peridynamic unit, and b is the volume force;

[0057] The plane strain equation using conventional state-based peridynamics is:

[0058]

[0059] Where K and G represent the bulk modulus and shear modulus in classical mechanics, ν is Poisson's ratio, ω is the influence function, x is the initial distance between peridynamic units, m is the weighted volume in peridynamics, m = (ωx) x, θ is the volume expansion term, e d is the deflected part of the elongation,

[0060] Step 2, setting the broken “bonds” based on the open porosity ρ = 1.68%;

[0061] Specifically, define the number of all "bonds" in the model as N, and set the number of broken "bonds" to n, satisfying The concrete of this embodiment is divided into 200×200 mass points, so the number of all “bonds” in the model is N=1105636, and the number of broken “bonds” is preset to n=18575.

[0062] Step 3, apply freeze-thaw stress state to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure, such as Figure 2 As shown;

[0063] Step 4: Apply freeze-thaw pressure to the broken "bonds" to dynamically capture the new cracks.

[0064] In each cycle, when a new "bond" breaks, the freeze-thaw force is applied to the particles at both ends of the broken "bond" to capture the crack tip. Figure 3-5 It can be seen that the concrete freeze-thaw damage cracks Figure 4 The damage value of the periphery is almost 1, indicating that the surface concrete peeling occurs after freezing and thawing; the middle part shows irregular expansion and bifurcated cracks. The concrete freeze-thaw simulation result diagram and the test result diagram show a high similarity.

[0065] Embodiment 2:

[0066] This embodiment provides a concrete freeze-thaw damage simulation system, including:

[0067] The "bond" generation module defines the coordinates of the particles and assigns concrete material properties based on the conventional state-based peridynamic model, creates family members of the particles and generates "bonds";

[0068] The initial damage setting module sets the fracture “key” based on the open porosity ρ;

[0069] The application module applies freeze-thaw stress state to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure;

[0070] The capture module applies freeze-thaw pressure to the broken "bonds" to achieve dynamic capture of new cracks.

[0071] Embodiment three:

[0072] An electronic device includes a memory, a processor, and a computer program stored and running on the memory, wherein the processor implements the above-mentioned concrete freeze-thaw damage simulation method when executing the program, including:

[0073] Based on the conventional state-based peridynamic model, the coordinates of the particles are defined and the concrete material properties are assigned, the family members of the particles are created and the "bonds" are generated;

[0074] Based on the open porosity ρ, the “bonds” for the fracture are set;

[0075] The freeze-thaw stress state is applied to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure;

[0076] Apply freeze-thaw pressure to the broken "bonds" to dynamically capture the new cracks.

[0077] Embodiment 4:

[0078] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the above-mentioned method for simulating freeze-thaw damage of concrete, including:

[0079] Based on the conventional state-based peridynamic model, the coordinates of the particles are defined and the concrete material properties are assigned, the family members of the particles are created and the "bonds" are generated;

[0080] Based on the open porosity ρ, the “bonds” for the fracture are set;

[0081] The freeze-thaw stress state is applied to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure;

[0082] Apply freeze-thaw pressure to the broken "bonds" to dynamically capture the new cracks.

[0083] Those skilled in the art should understand that the modules or steps of the present disclosure can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present disclosure is not limited to any specific combination of hardware and software.

[0084] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0085] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A method for simulating freeze-thaw damage of concrete, characterized in that: The following steps are involved: Based on the conventional state-based peridynamic model, the coordinates of the particles are defined and the concrete material properties are assigned, the family members of the particles are created and the "bonds" are generated; Based on the open porosity ρ, set the "bond" for breaking; The freeze-thaw stress state is applied to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure; Apply freeze-thaw pressure to the broken "bonds" to dynamically capture new cracks.

2. A method for simulating freeze-thaw damage of concrete according to claim 1, characterized in that: The conventional state-based peridynamic equation of motion is as follows: Where ρ is the peridynamic unit density, is the acceleration of the peridynamic unit, H(x) is the near-field integration domain, T is the force state between the peridynamic units, dV is the volume of the peridynamic unit, and b is the volume force; The force state in the conventional state-based peridynamic equation is expressed as: Among them, K and G represent the bulk modulus and shear modulus in classical mechanics, and ν is Poisson's ratio; ω is the influence function, x is the initial distance between peridynamic units, m is the weighted volume in peridynamics, m = ( ωx ) x ; θ is the volume expansion term, e d is the deflected part of the elongation, In peridynamics, damage is defined as follows: Where φ(x) represents the damage degree of the peridynamic unit, d (ξ) represents the breaking of the "bond" between two peridynamic units; when d When (ξ) = 0, it means the "bond" is complete; when d When (ξ) = 1, it means that the "bond" is broken.

3. A method for simulating freeze-thaw damage of concrete according to claim 2, characterized in that: The breaking criterion of the "bond" adopts the energy density criterion. When the energy density of the "bond" is greater than the critical energy density, the "bond" breaks, that is, d (ξ)=1, the critical energy density is expressed as: Among them, G c is the critical energy release rate, and h is the plate thickness for two-dimensional problems.

4. A method for simulating freeze-thaw damage of concrete according to claim 1, characterized in that: Assume that the number of all "bonds" in the model is N, and the number of broken "bonds" is set to n, satisfying Randomize the "bonds" that are pre-set to break.

5. A method for simulating freeze-thaw damage of concrete according to claim 1, characterized in that: The freeze-thaw stress state is applied to the particles at both ends of the broken "bond", specifically: the freeze-thaw pressure on the crack surface is defined as P, and the freeze-thaw stress state applied between the peridynamic particles is defined as T ice , this force state does not disappear with the destruction of the bond between the particles, and the magnitude of this force state is related to the length of the "bond": T ice =t ice ·(1-x / d) Among them, ξ is the length of the "key" and δ is the sight distance; The freeze-thaw pressure P and freeze-thaw state T ice The relationship is:

6. A method for simulating freeze-thaw damage of concrete according to claim 5, characterized in that: The freeze-thaw state is expressed as:

7. A method for simulating freeze-thaw damage of concrete according to claim 1, characterized in that: Dynamic capture of newly formed cracks. Specifically, when a new "bond" breaks, it indicates that the crack is expanding. At this time, pore water will enter the crack and generate new freeze-thaw pressure, thereby capturing the crack tip and simulating the migration of pore water.

8. A concrete freeze-thaw damage simulation system, characterized in that: include: The "bond" generation module defines the coordinates of the particles and assigns concrete material properties based on the conventional state-based peridynamic model, creates family members of the particles and generates "bonds"; Initial damage setting module, which sets the fracture "key" based on the open porosity ρ; The application module applies freeze-thaw stress to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure; The capture module applies freeze-thaw pressure to the broken "bonds" to achieve dynamic capture of new cracks.

9. An electronic device comprising a memory, a processor and a computer program stored and running on the memory, characterized in that: When the processor executes the program, a method for simulating freeze-thaw damage of concrete according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the method for simulating freeze-thaw damage of concrete according to any one of claims 1 to 7 is implemented.

Images