A reinforced concrete slab penetration damage prediction method and system based on unconventional state type near field dynamics

Abstract

This invention belongs to the field of structural impact resistance numerical simulation technology, and discloses a method and system for predicting penetration failure of reinforced concrete slabs based on unconventional near-field dynamics. The method includes: discretizing concrete, reinforcing steel, and the projectile into material points; using a common-node model to achieve displacement coordination between the reinforcing steel and concrete, avoiding additional interface elements; introducing a Holmquist-Johnson-Cook constitutive model to describe the dynamic response of concrete under high pressure and high strain rate; proposing an hourglass force model coupled with material damage variables to automatically attenuate the hourglass force in the material failure region, suppressing zero-energy modes and avoiding artificial stiffness. The motion of the material points is solved through explicit time history iteration, and bond fracture is determined based on the critical elongation rate, outputting the damage morphology of the reinforced concrete slab and the residual velocity after projectile penetration. This invention can be used for the assessment and design of the penetration resistance performance of reinforced concrete components such as protective doors, nuclear containment structures, and underground structures.

Description

Technical Field

[0001] This invention belongs to the field of structural impact resistance numerical simulation technology, specifically relating to a method and system for predicting penetration failure of reinforced concrete slabs based on unconventional near-field dynamics. Background Technology

[0002] In military protective engineering, nuclear facility containment structures, and important civilian buildings, reinforced concrete slabs must withstand the penetration of high-speed projectiles. The design phase should accurately predict the failure mode of the slab and the residual velocity after projectile penetration to assess the remaining structural load-bearing capacity. Currently, the finite element method is mainly used for penetration simulation, but it has the following problems: severe distortion occurs in concrete elements near the projectile under high-speed impact, leading to decreased accuracy or even premature termination of the calculation; crack propagation paths are limited by mesh boundaries, making it difficult to characterize the actual damage appearance; the interface between concrete and reinforcement needs to be modeled separately and contact conditions defined, increasing modeling complexity and computational load.

[0003] Unconventional peri-field dynamics uses integral equations to describe the interactions between material points, eliminating the need for pre-defined crack paths and naturally simulating crack initiation, propagation, and debris ejection. It can also directly utilize traditional continuum constitutive models, facilitating engineering applications. However, in simulating the penetration of reinforced concrete slabs, this method often employs bond reinforcement or iterative constraint methods for the coupling between reinforcement and concrete, resulting in low computational efficiency. Furthermore, without suppressing inherent zero-energy modes, numerical oscillations and computational instability can occur. To address these shortcomings, this invention proposes a method for predicting the penetration failure of reinforced concrete slabs based on unconventional peri-field dynamics. Summary of the Invention

[0004] To address the challenge of accurately predicting the failure morphology of reinforced concrete slabs under high-speed projectile penetration in existing technologies, this invention provides a method and system for predicting the penetration failure of reinforced concrete slabs based on unconventional near-field dynamics. The method includes: discretizing concrete, reinforcing steel, and the projectile into material points; employing a common-node model to achieve displacement coordination between the reinforcing steel and concrete, avoiding additional interface elements; introducing a Holmquist-Johnson-Cook (HJC) constitutive model to describe the dynamic response of concrete under high pressure and high strain rate; proposing an hourglass force model coupled with material damage variables to automatically attenuate the hourglass force in the material failure region, suppressing zero-energy modes and avoiding artificial stiffness. The motion of the material points is solved through explicit time-history iteration, and bond fracture is determined based on the critical elongation rate, outputting the damage morphology of the reinforced concrete slab and the residual velocity after projectile penetration. This invention can be used for the assessment and design of the penetration resistance performance of reinforced concrete components such as protective doors, nuclear containment structures, and underground structures.

[0005] To achieve the above objectives, the present invention provides the following solution: A method for predicting penetration failure of reinforced concrete slabs based on unconventional near-field dynamics, the method comprising: Step 1: Obtain the geometric parameters, material parameters, and initial boundary conditions of the target reinforced concrete slab and the penetrating projectile; Step 2: Establish a near-field dynamic penetration simulation model for reinforced concrete slabs; Step 3: Perform explicit time history calculation of the near-field dynamics penetration simulation model, update the motion state of the material points and calculate the damage in each time step; Step 4: Terminate the calculation when the calculation time reaches the preset analysis duration, and output the prediction results, including the final damage morphology of the reinforced concrete slab and the residual velocity of the projectile after penetrating the slab.

[0006] Preferably, in step 2, the method for establishing a near-field dynamic penetration simulation model of the reinforced concrete slab includes: Step 2.1 Discretize the concrete, steel reinforcement, and projectile into near-field dynamic material points containing material property information, wherein the steel reinforcement material points and the concrete material points are coupled in a common node manner; Step 2.2 Construct a dynamic damage constitutive model for concrete material, as well as constitutive models for steel reinforcement and elastic material. The dynamic response of concrete material is characterized by the Holmquist-Johnson-Cook (HJC) model. Step 2.3 Introduce an hourglass force model that considers damage effects to suppress zero-energy modes in unconventional peri-field dynamics calculations; Step 2.4 Configure the initial velocity conditions of the projectile and the boundary constraints of the reinforced concrete slab.

[0007] Preferably, in step 2.1, the concrete, reinforcing steel, and the projectile are discretized into near-field dynamic material points containing material property information, wherein the method of coupling the reinforcing steel material points and the concrete material points using a common-node approach includes: ; in For deformation gradient, For the concrete neighborhood, , For concrete material points, For the influence function, , For the steel reinforcement material point, For shape tensors, For unit tensors, For the rebar neighborhood, For concrete material points Displacement, For concrete material points Displacement, For the material points of the reinforcing steel Displacement; The volume integral is the volume of the concrete material within a point region. It represents the volume integral within the region of the reinforcing steel material.

[0008] Preferably, in step 2.2, constructing a dynamic damage constitutive model for concrete material, as well as constitutive models for reinforcing steel and elastic material, wherein the method for characterizing the dynamic response of concrete material using the Holmquist-Johnson-Cook (HJC) model includes: ; in To normalize the equivalent effect, This is the normalized cohesive strength coefficient. Damage variables characterizing the degree of material damage, This is the normalized pressure hardening coefficient. For normalized pressure that depends on the equation of state, This is the actual hydrostatic pressure. For compressive strength, The stress hardening index. The strain rate coefficient, Normalized strain rate; The damage evolution equation is: ; in, For HJC damage variables, For the equivalent plastic strain increment, For the plastic volumetric strain increment, , The damage constant is For normalization pressure, This represents the normalized tensile strength.

[0009] Preferably, in step 2.3, the method of introducing an hourglass force model that considers damage effects to suppress zero-energy modes in unconventional peridynamic calculations includes: ; in, To correct the stress of the hourglass, The hourglass coefficient, The equivalent strain corresponding to zero energy displacement, This is the bulk modulus.

[0010] Preferably, in step 3, the method for performing explicit time history calculations of the near-field dynamics penetration simulation model, updating the motion state of the material points and calculating damage in each time step includes: Step 3.1 Calculate the interaction forces between material points in the current time step, and solve for the acceleration of each material point based on the equation of motion; Step 3.2 Update the velocity and displacement of the material points using an explicit integral scheme; Step 3.3 Determine whether the bonds between material points have broken according to the critical elongation criterion, and update the damage state; Step 3.4 Determine whether the current calculation time has reached the preset analysis duration. If not, proceed to the next time step to continue calculation. If it has, terminate the calculation and output the prediction result.

[0011] Preferably, in step 3.1, the method for calculating the interaction forces between material points within the current time step and solving for the acceleration of each material point based on the equations of motion includes: ; in, for t Momentary Matter Point acceleration, and For a point of matter and its near-field range The material points inside, For matter points density, for t Momentary Matter Point displacement, For matter points The volume of the integration field, For matter points physical density, and The interaction force between material points within the same material is expressed as: ; in, , It is the Cauchy stress tensor, derived from the constitutive models of steel bars, concrete, and projectiles.

[0012] Preferably, in step 3.2, the method of updating the velocity and displacement of the material point using an explicit integral scheme includes: ; ; ; in, For the first Matter point during step displacement, For the first The speed of the step, For the first acceleration during step, For time step, No. Matter point during step The location coordinates.

[0013] Preferably, in step 3.3, the method for determining whether the bonds between material points have broken based on the critical elongation criterion and updating the damage state includes: In the critical elongation criterion, the material point and Elongation of the bond between Defined as: ; in, Let be the relative position vector of two points in the initial configuration. Let be the relative displacement vector between the two points. , For matter points and displacement, The distance between two points in the current configuration. The distance between two points in the initial configuration; if the matter point Its near-neighborhood Another material point inside Elongation of the bond between Exceeding the critical elongation s If the value is 0, then the bond breaks. The distance between the material points is given; and the distance to the target material point is calculated. The percentage of all broken bonds in the near-field neighborhood is the damage value of that material point; critical elongation. s 0 is the material fracture energy and bulk modulus For three-dimensional problems: ; material points Damage variables Defined as the ratio of the number of broken bonds within the near-field range of a substance point to the total number of bonds: ; in, It is a discontinuous function when the bond is not broken. When the bond breaks Accordingly, This indicates that the materials are intact. This indicates that the material is completely damaged.

[0014] The present invention also provides a system for predicting the penetration failure of reinforced concrete slabs based on unconventional near-field dynamics. The system is used to implement the aforementioned method and includes: an acquisition module, a construction module, an execution module, and a termination module. The acquisition module is used to acquire the geometric parameters, material parameters, and initial boundary conditions of the target reinforced concrete slab and the penetrating projectile. The construction module is used to establish a near-field dynamic penetration simulation model of reinforced concrete slabs; The execution module is used to perform explicit time history calculations of the near-field dynamics penetration simulation model, update the motion state of the material points and calculate the damage in each time step; The termination module is used to terminate the calculation when the calculation time reaches the preset analysis duration and output the prediction results, including the final damage morphology map of the reinforced concrete slab and the residual velocity of the projectile after penetrating the slab.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Based on the near-field dynamics method, without the need to preset the crack path, the crack initiation, propagation, bifurcation, penetration and fragmentation process of reinforced concrete slab under high-speed penetration are directly output, avoiding the crack morphology distortion caused by mesh distortion in the finite element method.

[0016] (2) By using a common node method to couple the steel bars and concrete material points, the force, displacement and velocity states between the concrete and steel bars can be effectively transferred without increasing the amount of calculation, simplifying the modeling process and reducing the computational complexity.

[0017] (3) Introduce the hourglass force model that takes into account damage. The hourglass correction stress decreases adaptively as the material damage variable increases. While suppressing the zero-energy mode, avoid introducing artificial stiffness into the failure region and maintain calculation stability. Attached Figure Description

[0018] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the penetration test setup for reinforced concrete slabs in an embodiment of the present invention (unit: mm). Figure 2 This is a schematic diagram of the solution process in an embodiment of the present invention; Figure 3 This is a schematic diagram of the near-field dynamics of the reinforced concrete slab and the projectile in an embodiment of the present invention. Figure 4 This is a comparison diagram of the predicted damage morphology of reinforced concrete slabs and the experimental results in the embodiments of the present invention; Figure 5 This is a comparison chart of the predicted projectile residual velocity and the experimental value in an embodiment of the present invention; Figure 6 This is a schematic diagram of a method for predicting the penetration failure of reinforced concrete slabs based on unconventional near-field dynamics, as described in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Example 1 To address the engineering problems of computational interruption and crack morphology distortion caused by mesh distortion in high-speed penetration simulation using the finite element method, this invention provides a method for predicting penetration failure of reinforced concrete slabs based on unconventional near-field dynamics, applicable to the design and performance evaluation of protective structures. For example... Figure 6 As shown, the method includes the following steps: Step 1: Obtain the geometric parameters, material parameters, and initial boundary conditions of the target reinforced concrete slab (length, width, thickness) and the penetrating projectile (length, diameter, warhead curvature, etc.); Step 2: Establish a near-field dynamic penetration simulation model for reinforced concrete slabs; Step 3: Perform explicit time history calculation of the near-field dynamics penetration simulation model, update the motion state of the material points and calculate the damage in each time step; Step 4: Terminate the calculation when the calculation time reaches the preset analysis duration, and output the prediction results, including the final damage morphology of the reinforced concrete slab and the residual velocity of the projectile after penetrating the slab.

[0023] In this embodiment, in step 1, the material parameters include the density, elastic modulus, compressive strength, tensile strength and strain rate effect parameters of concrete, and the density, elastic modulus and yield strength of steel bars and projectiles; the initial boundary conditions include the support type of concrete, the penetration velocity of projectiles and penetration angle, etc.

[0024] In this embodiment, step 2, pre-constructing the near-field dynamics reinforced concrete slab penetration simulation model, includes: Step (2.1) Discretize the concrete, steel bars and the projectile into near-field dynamic material points containing material property information, wherein the steel bar material points and the concrete material points are coupled in a common node manner; Step (2.2) Construct a dynamic damage constitutive model for concrete material, as well as constitutive models for steel reinforcement and elastic material, wherein the dynamic response of concrete material is characterized by the HJC model; Step (2.3) Introduce an hourglass force model that considers damage effects to suppress zero-energy modes in unconventional peri-field dynamics calculations; Step (2.4) Configure the initial velocity conditions of the projectile and the boundary constraints of the reinforced concrete slab.

[0025] Further, in step (2.1), the concrete, reinforcing steel, and the projectile are discretized into a series of material points containing material information. During discretization, the model is divided into a series of hexahedral elements, with uniform element distribution and consistent size. The maximum discretization spacing does not exceed 1 / 100 of the maximum side length of the solid geometric model, and the specific spacing is adjusted according to the required calculation accuracy. (Reinforcing steel material points) With concrete material points Using a shared-node coupling method, when the spatial distance between two nodes is less than the near-field range δ, they are defined as a shared-node pair, sharing displacement and velocity motion states in the calculation; the deformation gradient of the shared-node pair simultaneously considers the concrete neighborhood. Internal concrete material points and the neighboring area of ​​the steel reinforcement Internal steel reinforcement material points The contribution is calculated as follows: in For deformation gradient, For the influence function, For concrete material points Displacement, For concrete material points Displacement, For the material points of the reinforcing steel Displacement; The volume integral is the volume of the concrete material within a point region. The volume integral of the steel reinforcement material within the region of the point. For shape tensors, It is a unit tensor.

[0026] Furthermore, in step (2.2), the HJC dynamic damage constitutive model of concrete material can effectively reflect the response changes of the concrete structure during penetration and is easy to embed into an unconventional near-field dynamics framework. Its yield surface equation is: in To normalize the equivalent effect, This is the normalized cohesive strength coefficient. Damage variables characterizing the degree of material damage, This is the normalized pressure hardening coefficient. For normalized pressure that depends on the equation of state ( (actual hydrostatic pressure) For compressive strength, The stress hardening index. The strain rate coefficient, Normalized strain rate; The damage evolution equation is: in, For HJC damage variables, For the equivalent plastic strain increment, For the plastic volumetric strain increment, , The damage constant is For normalization pressure, The normalized tensile strength is used. This model is used to describe the mechanical response of concrete under high strain rate and high pressure conditions, as well as the accumulation process of compressive damage; the reinforcement adopts the Drucker-Prager (DP) constitutive model, and the projectile adopts the linear elastic constitutive model.

[0027] Furthermore, in step (2.3), an hourglass force model considering damage effects is proposed, which can effectively improve the model's stability and computational accuracy, making the solution more accurate. Its corrected hourglass stress expression is: in, To correct the stress of the hourglass, The hourglass coefficient, Bulk modulus This represents the equivalent strain corresponding to zero-energy displacement. The model couples the hourglass control force with the material damage variable, ensuring that the hourglass force naturally decays in areas where the material has been damaged and softened, thus avoiding the introduction of artificial stiffness in areas of complete failure.

[0028] Further, in step (2.4), the projectile is discretized into a set of material points, each of which is a material point of the projectile. i They are all given a certain initial velocity at the initial moment. : in , , They are projectile material points i The velocity components along the x, y, and z directions at the initial moment. When discretizing the reinforced concrete slab model, if 2-3 layers of material points at the edge of the slab are set as a fixed boundary layer, then the material points in this region... j displacement It can be represented as: in , , Fixed boundary layer material points for reinforced concrete slabs j Displacement components along the x, y, and z directions. By ensuring that the displacement in this region remains zero, a fixed constraint can be achieved.

[0029] In this embodiment, step 3, which involves performing explicit time history calculations of the near-field dynamics penetration simulation model, includes: Step (3.1) Calculate the interaction forces between material points in the current time step, and solve for the acceleration of each material point according to the equation of motion; Step (3.2) Update the velocity and displacement of the material points using an explicit integral scheme; Step (3.3): Determine whether the bonds between material points have broken according to the critical elongation criterion, and update the damage state; Step (3.4) Determine whether the current calculation time has reached the preset analysis time. If not, proceed to the next time step to continue the calculation. If it has, terminate the calculation and output the prediction result.

[0030] Further, in step (3.1), the unconventional peridynamic equations of motion are as follows: in, for t Momentary Matter Point acceleration, and For a point of matter and its near-field range The material points inside, For matter points density, for t Momentary Matter Point displacement, For matter points The volume of the integration field, For matter points Physical density. and The interaction force between material points within the same material can be expressed as: in, , It is the Cauchy stress tensor, derived from the constitutive models of steel bars, concrete, and projectiles.

[0031] Furthermore, in step (3.2), the iterative method for the explicit integration scheme is as follows: in, For the first Matter point during step displacement, For the first The speed of the step, For the first acceleration during step, For time step, No. Matter point during step The location coordinates.

[0032] Further, in step (3.3), the damage level of the material points is assessed according to the critical elongation criterion to determine whether bond failure has occurred. In the critical elongation criterion, the material points... and Elongation of the bond between Defined as: in, Let be the relative position vector of two points in the initial configuration. The relative displacement vector between two points ( , For matter points and (displacement) The distance between two points in the current configuration. This is the distance between two points in the initial configuration. If the matter point... Its near-neighborhood ( Another material point within the distance between material points (where the distance between material points is the distance between material points). Elongation of the bond between Exceeding the critical elongation s If the value is 0, then the bond breaks; this is used to calculate the effect on the target material point. The percentage of broken bonds in the near-field neighborhood is the damage value of that material point. Critical elongation. s 0 is the material fracture energy and bulk modulus For three-dimensional problems: This will further transform the material points Damage variables Defined as the ratio of the number of broken bonds within the near-field range of a substance point to the total number of bonds: in, It is a discontinuous function when the bond is not broken. When the bond breaks Accordingly, This indicates that the materials are intact. This indicates that the material is completely damaged.

[0033] Further, in step (3.4), if the current calculation time... The preset analysis time has not been exceeded. Continue running the calculation for the next time step; terminate the calculation when the calculation time reaches the preset analysis duration, and output the prediction results.

[0034] Example 2 This embodiment is used to verify the accuracy of the present invention in predicting the damage morphology and residual velocity of reinforced concrete slabs under projectile penetration. For example... Figure 1 As shown, the reinforced concrete slab used is a square slab with dimensions of 675 mm × 675 mm × 200 mm. The static compressive strength of the concrete is 48.0 MPa, the direct tensile strength is 4.0 MPa, the density is 2400 kg / m³, the elastic modulus is 35 GPa, and the Poisson's ratio is 0.2. Three layers of reinforcing mesh are arranged within the slab, each layer consisting of bidirectional orthogonally arranged reinforcing bars with a diameter of 8 mm and a spacing of 82 mm. The thickness of the protective layer is determined by calculation. The reinforcing bar density is 7850 kg / m³, the elastic modulus is 210 GPa, the Poisson's ratio is 0.29, the yield strength is 400 MPa, and the hardening modulus is 1.2 GPa. The projectile is an Ogiive nose-shaped steel projectile with a diameter of 25.3 mm, a length of approximately 152 mm, a density of 7850 kg / m³, an elastic modulus of 210 GPa, and a Poisson's ratio of 0.29. The projectile's initial impact velocity was 540 m / s, and it was incident perpendicular to the plate surface.

[0035] like Figure 3 As shown, a near-field dynamics model is established according to the following: (1) Discretization: The concrete slab, steel mesh, and projectile are discretized into near-field dynamic material points. Considering both computational accuracy and efficiency, the discretization spacing of the material points is taken as Δx = 2 mm. The steel reinforcement material points are arranged at the same spacing along the steel reinforcement axis and are coupled with the concrete material points located in the same spatial position using a common node coupling scheme: when the spatial distance between the steel reinforcement material points and the concrete material points is less than the near-field range δ, the two are defined as a common node pair, sharing displacement and velocity motion states in the calculation.

[0036] (2) Near-field range setting: The near-field range δ of concrete and steel reinforcement is 4 times the discrete spacing, i.e., δ = 8 mm. The near-field range of the projectile is also set to 8 mm.

[0037] (3) Constitutive parameters of materials: The HJC dynamic damage constitutive model was used for concrete, and the ideal elastic-plastic constitutive model was used for steel reinforcement. The hardening modulus after yielding was set to 1.2 GPa.

[0038] (4) Hourglass force model parameters: The hourglass coefficient is 0.05. This value is within the effective range of 0.01 to 0.1 to fully suppress the zero-energy mode without introducing too much artificial stiffness.

[0039] (5) Contact and Boundary Conditions: The reinforced concrete slab is set as a free boundary around its perimeter. The projectile is given an initial velocity of 540 m / s, perpendicular to the slab surface. The time step is 1 × 10⁻⁶ m / s. -7 s, preset analysis duration 1×10 -3 s.

[0040] To begin the calculation, such as... Figure 2 As shown, the specific implementation steps are as follows: (1) Input the geometric and material parameters of the concrete, steel bars, and projectile, as well as the initial impact velocity.

[0041] (2) Initialize all material points, including position, velocity and acceleration; establish a list of common node pairs.

[0042] (3) Search for neighboring material points within the near field range of each material point and establish a near field list.

[0043] (4) Start the time step loop, t = 0.

[0044] (5) Calculate the deformation gradient, velocity gradient and incremental strain for each material point.

[0045] (6) Update the stress and damage variables of concrete material points based on the HJC constitutive model; update the stress of steel reinforcement material points based on the elastoplastic constitutive model.

[0046] (7) Calculate the hourglass correction force using the hourglass force model that takes damage into account, and update the force state.

[0047] (8) Based on the equation of motion, the acceleration, velocity and displacement of all material points are updated using the explicit prediction-correction integral scheme; the same displacement increment is used for the steel reinforcement and concrete material points in the common node pair.

[0048] (9) Judgment t Has the preset analysis duration of 1 × 10⁻⁶ been reached? - ³ s. If not reached, then t = t + Δ t Return to step (5); if the target has been reached, terminate the calculation.

[0049] After the calculation is completed, a damage contour map of the concrete slab is output. For example... Figure 4 As shown in the comparative test photos of the actual damage, the present invention successfully predicted the circular pitting area at the center of the front surface of the reinforced concrete slab and the circumferential crack on the back side of the slab. A crushing zone was formed in front of the projectile, and a conical collapse zone was formed on the back side due to stress wave reflection. The distribution characteristics and propagation range of the cracks were consistent with the test results. Figure 5 As shown, the velocity tends to stabilize after the projectile completely penetrates the plate. The residual velocity predicted by this invention is 324.35 m / s, which is approximately 7.74% different from the experimentally measured value of 351.58 m / s, indicating a good agreement between the prediction and the actual velocity.

[0050] Example 3 The present invention also provides a system for predicting the penetration failure of reinforced concrete slabs based on unconventional near-field dynamics. The system is used to implement the method described in Embodiment 1. The system includes: an acquisition module, a construction module, an execution module, and a termination module. The acquisition module is used to acquire the geometric parameters, material parameters, and initial boundary conditions of the target reinforced concrete slab and the penetrating projectile. A building module is used to create a near-field dynamic penetration simulation model for reinforced concrete slabs; The execution module is used to perform explicit time history calculations of the near-field dynamics penetration simulation model, update the motion state of the material points and calculate the damage in each time step; The termination module is used to terminate the calculation when the calculation time reaches the preset analysis duration and output the prediction results, including the final damage morphology map of the reinforced concrete slab and the residual velocity of the projectile after penetrating the slab.

[0051] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for predicting penetration failure of reinforced concrete slabs based on unconventional near-field dynamics, characterized in that, The method includes: Step 1: Obtain the geometric parameters, material parameters, and initial boundary conditions of the target reinforced concrete slab and the penetrating projectile; Step 2: Establish a near-field dynamic penetration simulation model for reinforced concrete slabs; Step 3: Perform explicit time history calculation of the near-field dynamics penetration simulation model, update the motion state of the material points and calculate the damage in each time step; Step 4: Terminate the calculation when the calculation time reaches the preset analysis duration, and output the prediction results, including the final damage morphology of the reinforced concrete slab and the residual velocity of the projectile after penetrating the slab.

2. The method according to claim 1, characterized in that, In step 2, the method for establishing a near-field dynamic penetration simulation model of a reinforced concrete slab includes: Step 2.1 Discretize the concrete, steel reinforcement, and projectile into near-field dynamic material points containing material property information, wherein the steel reinforcement material points and the concrete material points are coupled in a common node manner; Step 2.2 Construct a dynamic damage constitutive model for concrete material, as well as constitutive models for steel reinforcement and elastic material. The dynamic response of concrete material is characterized by the Holmquist-Johnson-Cook (HJC) model. Step 2.3 Introduce an hourglass force model that considers damage effects to suppress zero-energy modes in unconventional peri-field dynamics calculations; Step 2.4 Configure the initial velocity conditions of the projectile and the boundary constraints of the reinforced concrete slab.

3. The method according to claim 2, characterized in that, In step 2.1, the concrete, reinforcing steel, and the projectile are discretized into near-field dynamic material points containing material property information. The method of coupling the reinforcing steel material points and the concrete material points using a common node approach includes: ； in For deformation gradient, For the concrete neighborhood, , For concrete material points, For the influence function, , For the steel reinforcement material point, For shape tensors, For unit tensors, For the rebar neighborhood, For concrete material points Displacement, For concrete material points Displacement, For the material points of the reinforcing steel Displacement; The volume integral is the volume of the concrete material within a point region. It represents the volume integral within the region of the reinforcing steel material.

4. The method according to claim 2, characterized in that, In step 2.2, a dynamic damage constitutive model of concrete material and constitutive models of steel reinforcement and elastic material are constructed. The method of characterizing the dynamic response of concrete material using the Holmquist-Johnson-Cook (HJC) model includes: ； in To normalize the equivalent effect, This is the normalized cohesive strength coefficient. Damage variables characterizing the degree of material damage, This is the normalized pressure hardening coefficient. For normalized pressure that depends on the equation of state, This is the actual hydrostatic pressure. For compressive strength, The stress hardening index. The strain rate coefficient, Normalized strain rate; The damage evolution equation is: ； in, For HJC damage variables, For the equivalent plastic strain increment, For the plastic volumetric strain increment, , The damage constant is For normalization pressure, This represents the normalized tensile strength.

5. The method according to claim 4, characterized in that, In step 2.3, the method of introducing an hourglass force model that considers damage effects to suppress zero-energy modes in unconventional near-field dynamics calculations includes: ； in, To correct the stress of the hourglass, The hourglass coefficient, The equivalent strain corresponding to zero energy displacement, This is the bulk modulus.

6. The method according to claim 5, characterized in that, In step 3, the method for performing explicit time history calculations of the near-field dynamics penetration simulation model, updating the motion state of the material points and calculating damage in each time step includes: Step 3.1 Calculate the interaction forces between material points in the current time step, and solve for the acceleration of each material point based on the equation of motion; Step 3.2 Update the velocity and displacement of the material points using an explicit integral scheme; Step 3.3 Determine whether the bonds between material points have broken according to the critical elongation criterion, and update the damage state; Step 3.4 Determine whether the current calculation time has reached the preset analysis duration. If not, proceed to the next time step to continue calculation. If it has, terminate the calculation and output the prediction result.

7. The method according to claim 6, characterized in that, In step 3.1, the method for calculating the interaction forces between material points within the current time step and solving for the acceleration of each material point based on the equations of motion includes: ； in, for t Momentary Matter Point acceleration, and For a point of matter and its near-field range Material points within, For matter points density, for t Momentary Matter Point displacement, For matter points The volume of the integration field, For matter points physical density, and The interaction force between material points within the same material is expressed as: ； in, , It is the Cauchy stress tensor, derived from the constitutive models of steel bars, concrete, and projectiles.

8. The method according to claim 7, characterized in that, In step 3.2, the method of updating the velocity and displacement of the material point using an explicit integral scheme includes: ； ； ； in, For the first Matter point during step displacement, For the first The speed of the step, For the first acceleration during step, For time step, No. Step-time material point The location coordinates.

9. The method according to claim 8, characterized in that, In step 3.3, the method for determining whether the bonds between material points have broken based on the critical elongation criterion and updating the damage state includes: In the critical elongation criterion, the material point and Elongation of the bond between Defined as: ； in, Let be the relative position vector of two points in the initial configuration. Let be the relative displacement vector between two points. , For matter points and displacement, The distance between two points in the current configuration. The distance between two points in the initial configuration; if the matter point Its near-neighborhood Another material point inside Elongation of the bond between Exceeding the critical elongation s If the value is 0, then the bond breaks. The distance between the material points is given; and the distance to the target material point is calculated. The percentage of all broken bonds in the near-field neighborhood is the damage value of that material point; critical elongation. s 0 is the material fracture energy and bulk modulus For three-dimensional problems: ； material points Damage variables Defined as the ratio of the number of broken bonds within the near-field range of a substance point to the total number of bonds: ； in, It is a discontinuous function when the bond is not broken. When the bond breaks Accordingly, This indicates that the materials are intact. This indicates that the material is completely damaged.

10. A system for predicting the penetration failure of reinforced concrete slabs based on unconventional near-field dynamics, the system being used to implement the method described in any one of claims 1-9, characterized in that, The system includes: an acquisition module, a construction module, an execution module, and a termination module; The acquisition module is used to acquire the geometric parameters, material parameters, and initial boundary conditions of the target reinforced concrete slab and the penetrating projectile. The construction module is used to establish a near-field dynamic penetration simulation model of reinforced concrete slabs; The execution module is used to perform explicit time history calculations of the near-field dynamics penetration simulation model, update the motion state of the material points and calculate the damage in each time step; The termination module is used to terminate the calculation when the calculation time reaches the preset analysis duration and output the prediction results, including the final damage morphology map of the reinforced concrete slab and the residual velocity of the projectile after penetrating the slab.

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