A method and system for simulating the freeze-thaw damage of concrete

Abstract

The present invention discloses a method and system for simulating the freeze-thaw damage of concrete, which relates to the technical fields of material failure prediction and mechanical numerical simulation; it includes defining the particle coordinates and assigning the concrete material properties based on the conventional state-based peridynamics model, creating the family members of the particles and generating "bonds"; setting the broken "bonds" based on the open porosity ρ; applying the freeze-thaw force state to the particles at both ends of the broken "bonds" to indicate that the pore or crack surface is subjected to the freeze-thaw pressure; applying the freeze-thaw pressure to the broken "bonds" to achieve the dynamic capture of the newly generated cracks. The present invention directly applies the freeze-thaw force state to the particles at both ends of the broken "bonds", and without constructing a complex temperature field model, it realizes the mesoscopic scale simulation of the concrete freeze-thaw process, effectively improves the calculation efficiency, and has achieved remarkable results in simulating freeze-thaw damage and crack propagation.

Description

Technical Field

[0001] The present 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 a significant factor in concrete durability in cold regions. This damage often causes severe spalling of the concrete surface, significantly reducing the thickness of the steel reinforcement cover, or even completely exposing it, seriously threatening the safety and stability of the structure. Furthermore, freeze-thaw damage can cause subtle and complex cracks within the concrete, weakening its rigidity and significantly reducing its overall strength.

[0003] When attempting to simulate such crack growth using methods based on continuum mechanics, researchers often encounter significant challenges, particularly mesh dependency, which can significantly compromise the accuracy and reliability of simulation results. To address this issue, peridynamics, a nonlocal theory, has made significant progress in crack simulation, providing new insights and tools for simulating crack growth in materials like concrete.

[0004] However, it's worth noting that the root cause of freeze-thaw damage in concrete often lies in water trapped in its internal pores. The size of these pores differs significantly from the overall size of the concrete specimen, necessitating that detailed modeling consider the impact of these tiny pore structures on overall performance. However, this elaborate modeling process undoubtedly significantly increases computational complexity and resource consumption, making practical applications challenging. Therefore, how to minimize computational resource consumption while maintaining simulation accuracy has become a key issue 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 broken “bonds” are set;

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

[0010] Apply the freeze-thaw pressure to the broken "bond" to achieve the dynamic capture of the newly generated crack.

[0011] In one of the embodiments, the near-field dynamics motion equation of the conventional state basis is as follows:

[0012]

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

[0014] The force state in the near-field dynamics equation of the conventional state basis is expressed as:

[0015]

[0016] Among them, K and G respectively represent the bulk modulus and shear modulus in classical mechanics, ν is the Poisson's ratio; ω is the influence function, x is the initial distance between the near-field dynamics units, m is the weighted volume in the near-field dynamics, m = (ωx)·x; θ is the volume expansion term, e d is the deviatoric part of the elongation,

[0017] In the near-field dynamics, the definition of damage is as follows:

[0018]

[0019] Among them, φ(x) represents the damage degree of the near-field dynamics unit, and d(ξ) represents the fracture situation of the "bond" between two near-field dynamics units; when d(ξ) = 0, it means the "bond" is intact; when d(ξ) = 1, it means the "bond" is broken.

[0020] In one of the embodiments, the fracture 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" fractures, that is, d(ξ) = 1, and 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 of the two-dimensional problem.

[0023] In one embodiment, let the number of all "bonds" in the model be N, and the number of "bonds" preset to break be n, satisfying Randomly distribute the "bonds" preset to break.

[0024] In one embodiment, apply the freeze-thaw force state to the particles at both ends of the broken "bond". Specifically: define the freeze-thaw pressure on the crack surface as P, and the freeze-thaw force state applied between peridynamic particles as T ice , and this force state does not disappear with the breakage of the bond between 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] where ξ is the length of the "bond" and δ is the line-of-sight distance;

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

[0028]

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

[0030]

[0031] In one embodiment, dynamically capture the newly generated crack. Specifically: when a new "bond" breaks, it indicates crack propagation. At this time, pore water will enter the crack and generate a new freeze-thaw pressure; therefore, the present invention applies the freeze-thaw force state to the particles at both ends of each broken "bond", thereby realizing the capture of the crack tip and simultaneously simulating the migration of pore water.

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

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

[0034] An initial damage setting module, based on the open porosity ρ, sets the broken "bonds";

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

[0036] A capture module, applies the freeze-thaw pressure to the broken "bond" to realize the dynamic capture of the newly generated crack.

[0037] According to the third aspect of the embodiments of the present disclosure, an electronic device is provided, including a memory, a processor, and a computer program running on the memory. When the processor executes the program, the mesoscopic scale simulation of the concrete freeze-thaw process is realized, effectively improving the calculation efficiency, and remarkable results have been achieved in simulating freeze-thaw damage and crack propagation.

[0038] According to the 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 mesoscopic scale simulation of the concrete freeze-thaw process is realized, effectively improving the calculation efficiency, and remarkable results have been achieved in simulating freeze-thaw damage and crack propagation.

[0039] The advantages of the above technical solutions adopted by the present invention compared with the prior art are as follows: The present invention directly applies the freeze-thaw force state on the particles at both ends of the broken "bond", and without constructing a complex temperature field model, the mesoscopic scale simulation of the concrete freeze-thaw process is realized, effectively improving the calculation efficiency, and remarkable results have been achieved in simulating freeze-thaw damage and crack propagation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The specification drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application.

[0041] Figure 1 is the flowchart of the concrete freeze-thaw damage simulation method of the present invention;

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

[0043] Figure 3 is the test result graph of the concrete freeze-thaw surface spalling of the embodiment of the present invention;

[0044] Figure 4 is the test result graph of the concrete freeze-thaw crack propagation of the embodiment of the present invention;

[0045] Figure 5 is the simulation result graph of the concrete freeze-thaw of the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

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

[0047] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this 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 also be understood that when the terms "comprise" and / or "include" are used in this specification, they specify 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 architectures, functions, and operations of methods and systems according to various embodiments of the present disclosure. It should be noted that each block in the flowchart or block diagram may represent a module, a program segment, or a part of code, and the module, program segment, or part of 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 blocks may occur in a different order from that marked in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the functions involved. Similarly, it should be noted that each block in the flowchart and / or block diagram, as well as the combination of blocks in the flowchart and / or block diagram, may be implemented using a dedicated hardware-based system for performing the specified functions or operations, or may be implemented using a combination of dedicated hardware and computer instructions.

[0050] This embodiment is described based on two-dimensional concrete with a size of 100 mm × 100 mm, a concrete grade of C40, and a total of 200 × 200 mass points. The viewing distance δ of each mass point is 3Δx = 1.5 mm. No boundary conditions are set for the model, and the boundary can move freely. The measured open porosity is 1.68%, and the freeze-thaw pressure P obtained by the finite element method is 58.3 MPa. 120 freeze-thaw cycles of the concrete are simulated and compared with the test results. The test uses a TDR-15D concrete rapid freeze-thaw testing machine with a temperature range of (-18 ± 2)°C to (18 ± 2)°C. Before the experiment starts, first soak the concrete in clean water for 4 days to ensure that the water fully penetrates the concrete. Then start the freeze-thaw testing machine and conduct the freeze-thaw cycle test according to the preset number of cycles and temperature.

[0051] Example 1:

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

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

[0054] Specifically, the governing equations of peridynamics in the classical state are as follows:

[0055]

[0056] In the formula, ρ is the density of the peridynamic element, is the acceleration of the peridynamic element, H(x) is the peridynamic integration domain, T is the force state between peridynamic elements, dV is the volume of the peridynamic element, and b is the body force;

[0057] Adopt the plane strain equation of peridynamics in the classical state:

[0058]

[0059] Among them, K and G respectively represent the bulk modulus and shear modulus in classical mechanics, ν is the Poisson's ratio; ω is the influence function, x is the initial distance between peridynamic elements, m is the weighted volume in peridynamics, m = (ωx)·x; θ is the volume dilation term, e d is the deviatoric part of the elongation,

[0060] Step 2: Based on the open porosity ρ = 1.68%, set the "broken" bonds;

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

[0062] Step 3: Apply the freeze-thaw force state to the mass points at both ends of the broken "bonds", indicating that the pore or crack surface is subjected to the freeze-thaw pressure, as Figure 2 shown;

[0063] Step 4: Apply the freeze-thaw pressure to the broken "bonds" to achieve dynamic capture of the newly generated cracks.

[0064] In each cycle, when a new "bond" breaks, apply the freeze-thaw force state to the mass points at both ends of the broken "bond" to achieve capture of the crack tip. As can be seen from Figures 3 - 5 it can be seen that the damage value of the concrete freeze-thaw damage crack Figure 4 in the [specific cycle] is almost 1, indicating that surface concrete spalling occurs after freeze-thaw; irregular expansion and bifurcation cracks appear in the middle. The concrete freeze-thaw simulation result diagram shows a high similarity with the test result diagram.

[0065] Example 2:

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

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

[0068] An initial damage setting module, based on the open porosity ρ, sets the broken "bonds";

[0069] An application module applies a freeze-thaw force 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] A capture module applies a freeze-thaw pressure to the broken "bond" to achieve dynamic capture of newly generated cracks.

[0071] Embodiment 3:

[0072] An electronic device includes a memory, a processor, and a computer program running on the memory. When the processor executes the program, it implements the above-mentioned concrete freeze-thaw damage simulation method, including:

[0073] Based on the conventional state-based peridynamics model, define the coordinates of particles and assign concrete material properties, create family members of the particles and generate "bonds";

[0074] Based on the open porosity ρ, set the broken "bonds";

[0075] Apply a freeze-thaw force state 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 a freeze-thaw pressure to the broken "bond" to achieve dynamic capture of newly generated cracks.

[0077] Embodiment 4:

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

[0079] Based on the conventional state-based peridynamics model, define the coordinates of particles and assign concrete material properties, create family members of the particles and generate "bonds";

[0080] Based on the open porosity ρ, set the broken "bonds";

[0081] Apply a freeze-thaw force state 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 "bond" to achieve dynamic capture of new cracks.

[0083] Those skilled in the art should understand that the above-mentioned modules or steps of the present disclosure can be implemented by a general-purpose computer device. Optionally, they can be implemented by program codes executable by the computing device, so that they can be stored in the storage device and executed by the computing device, or they can be separately fabricated into individual integrated circuit modules, or multiple modules or steps among them can be fabricated 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 are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

[0085] Although the specific implementation manners of the present disclosure are described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present disclosure. Those skilled in the art should understand that based on the technical solutions of the present disclosure, various modifications or deformations that can be made without creative efforts by those skilled in the art are still within the protection scope of the present disclosure.

Claims

1. A method for simulating freeze-thaw damage of concrete, characterized in that, It includes the following steps: Based on the conventional state-based peridynamics model, define the coordinates of the particles and endow the concrete material properties, create the family members of the particles and generate "bonds"; Based on the open porosity ρ, set the broken "bonds"; Apply the freeze-thaw force state to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to the freeze-thaw pressure. Specifically: Define the freeze-thaw pressure on the crack surface as P, and the freeze-thaw force state applied between the peridynamic particles as T ice , this force state does not disappear with the breakage 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 - ξ / δ) Where ξ is the length of the "bond" and δ is the line-of-sight distance; The freeze-thaw pressure P and the freeze-thaw force state T ice are related as follows: Apply freeze-thaw pressure to the broken "bonds" to achieve dynamic capture of the newly generated cracks.

2. The concrete freeze-thaw damage simulation method according to claim 1, wherein, The conventional state-based peridynamics motion equation is as follows: where ρ is the peridynamic element density, is the acceleration of the peridynamic element, H(x) is the peridynamic integration domain, T is the force state between peridynamic elements, dV is the volume of the peridynamic element, and b is the body force; The force state in the conventional state-based peridynamics equation is expressed as: Among them, K and G respectively represent the bulk modulus and shear modulus in classical mechanics, ν is the Poisson's ratio; ω is the influence function, x is the initial distance between peridynamic units, and m is the weighted volume in peridynamics. θ is the volumetric dilatation term. e d is the deviatoric part of the elongation. In peridynamics, the definition of damage is as follows: Where φ(x) represents the damage degree of the peridynamics element, and d(ξ) represents the fracture condition of the "bond" between two peridynamics elements; when d(ξ) = 0, it means the "bond" is intact; when d(ξ) = 1, it means the "bond" is broken.

3. The concrete freeze-thaw damage simulation method according to claim 2, wherein The fracture 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" fractures, that is, d(ξ) = 1, and 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. The method for simulating freeze-thaw damage of concrete according to claim 1, characterized in that Let the number of all "keys" in the model be N, and the number of "keys" preset to be broken be n, satisfying Randomly distribute the "keys" preset to be broken.

5. The concrete freeze-thaw damage simulation method according to claim 1, characterized in that The freeze-thaw force state is expressed as: 。 6. The method for simulating freeze-thaw damage of concrete according to claim 1, wherein, The dynamic capture of the newly generated cracks is specifically as follows: when a new "bond" fractures, it indicates crack propagation. At this time, pore water will enter the crack, generating a new freeze-thaw pressure, thereby achieving the capture of the crack tip and simultaneously simulating the migration of pore water.

7. A simulation system for freeze-thaw damage of concrete, characterized in that, It includes: A "bond" generation module, which based on the conventional state-based peridynamics model, defines the coordinates of the particles and endows the concrete material properties, creates the family members of the particles and generates "bonds"; An initial damage setting module, which based on the open porosity ρ, sets the broken "bonds"; An application module applies a freeze-thaw force state to the particles at both ends of the broken "bond", indicating that the pore or crack surface is subjected to freeze-thaw pressure. Specifically, the freeze-thaw pressure on the crack surface is defined as P, and the freeze-thaw force state applied between peridynamic particles is T ice , and this force state does not disappear with the breakage of the bond between particles, and the magnitude of this force state is related to the length of the "bond": T ice = t ice ·(1 - ξ / δ) Where ξ is the length of the "bond" and δ is the line-of-sight distance; The freeze-thaw pressure P and the freeze-thaw force state T ice are related as follows: A capture module, which applies freeze-thaw pressure to the broken "bonds" to achieve dynamic capture of the newly generated cracks.

8. An electronic device, comprising a memory, a processor, and a computer program running on the memory, characterized in that, When the processor executes the program, it implements a concrete freeze-thaw damage simulation method according to any one of claims 1-6.

9. A computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements a concrete freeze-thaw damage simulation method according to any one of claims 1-6.

Images