Method and system for fast generation of two-dimensional multiscale model of fiber reinforced recycled concrete

Abstract

The application provides a method and system for quickly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete, considering the influence of the shape and type of aggregate and the interaction mechanism of the fiber-cement base interface, quickly generating all microphase structures and interfaces, and effectively simulating the real situation with high efficiency and high quality. The method comprises the following steps: step 1, according to the information of the fiber-reinforced recycled concrete to be simulated, generating a corresponding size, shape and position of the recycled concrete two-dimensional plane micro model at the corresponding region of the concrete component macro model; step 2, according to the aggregate gradation of the micro model, calculating the number of recycled coarse aggregates in each particle size range; step 3, randomly generating the center point coordinate position of the circular aggregate in the micro model, and avoiding overlapping between the aggregates; step 4, randomly generating the shape of the aggregate in the micro model; step 5, setting different recycled coarse aggregate replacement rates; and step 6, establishing a fiber-interface model.

Description

Technical Field

[0001] This invention belongs to the field of fiber-reinforced concrete simulation technology, specifically relating to a method and system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete. Background Technology

[0002] Recycled concrete, as a green and circular resource, is formed by crushing and screening waste concrete and then mixing it with natural aggregates in a certain proportion and gradation. Because recycled aggregates have a large amount of old mortar adhering to their surfaces, the microstructure of recycled concrete is more complex than that of ordinary concrete, specifically comprising a six-phase structure: natural aggregate, natural aggregate interface, old mortar interface, old mortar interface, new mortar, and new mortar interface. Therefore, numerous studies have shown that the mechanical properties of recycled concrete are inferior to those of ordinary concrete. However, through appropriate modification treatments (such as the addition of suitable fiber), its mechanical properties can still be effectively improved, thus allowing it to replace ordinary concrete in practical engineering applications.

[0003] With the continuous development of computer technology and the maturation of related numerical calculation techniques, stochastic aggregate models that consider the internal microstructure of recycled concrete, such as aggregate shape, gradation, and interfaces, have begun to be adopted to study the microscopic failure mechanism of materials. Currently, the method of simplifying aggregates into circles and randomly distributing them using the Monte Carlo method to generate a circular stochastic aggregate model is relatively mature and common. However, the shape, type, and replacement rate of the aggregates still have a certain impact on the calculation results, especially for recycled concrete, which has many weak points in its internal structure. The structure and properties of each component have a significant impact on the mechanical properties of recycled concrete and cannot be ignored. For fibers, from a numerical modeling perspective, the common practice is to simplify fibers into linear elements. However, this method is relatively crude and does not consider the interaction mechanism of the fiber-cement matrix interface, resulting in a significant difference from reality. Summary of the Invention

[0004] This invention is made to solve the above-mentioned problems, and aims to provide a method and system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete. It takes into account the influence of aggregate shape and type and the interaction mechanism of fiber-cement matrix interface, and rapidly generates all micro-phase structures and interfaces, which has both high efficiency and high quality, and effectively simulates real conditions.

[0005] To achieve the above objectives, the present invention adopts the following solution:

[0006] <Method>

[0007] like Figure 1 As shown, the present invention provides a method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete, characterized by comprising the following steps:

[0008] Step 1: Based on the information of the fiber-reinforced recycled concrete to be simulated, generate a two-dimensional planar model (two-dimensional planar mesoscopic model of recycled concrete) of the corresponding size, shape, and position of the recycled concrete beam in a local area of ​​the macroscopic model (e.g., the research focus area of ​​the large reinforced concrete component, the middle part of the beam); specifically, within the boundary of a regular quadrilateral of arbitrary size, by inputting the horizontal and vertical distances to a vertex of the quadrilateral, as well as the length and width of the mesoscopic region, a mesoscopic model of any given size can be generated at any local location of the macroscopic model;

[0009] Step 2: Based on the aggregate gradation of the microstructure model, calculate the number of recycled coarse aggregates within each particle size range; based on the Varavan aggregate gradation formula, calculate the number n(D) of recycled coarse aggregates within each particle size range. i D j ):

[0010]

[0011] n(D i D j )=(P(D j )-P(D j ))×length×width / v[D i D j ];

[0012] In the formula, v[D i D j ] represents D i ~D j The area of ​​aggregate representing the particle size within the range. k D represents the volume fraction of aggregate; max Indicates the maximum coarse aggregate particle size;

[0013] Step 3: Randomly generate the coordinates of the center point of the circular aggregate in the microscopic model, and avoid overlap between aggregates;

[0014] Step 4: Randomly generate aggregate shapes in the microscopic model; including the following sub-steps:

[0015] Step 4.1, random generation of interlayer geometry:

[0016] A certain number of points are randomly generated on the virtual circular boundary line of the current layer. The number of points is a random integer within a given range. To determine the specific coordinates of the i-th point (i = 0, 1, 2, ..., n-1) on the circle with n points, the angle each_angle between point i and the x-axis is first randomly generated:

[0017] each_angle=random.uniform(2πi / n,2π(i+1) / n);

[0018] Next, based on the diameter D of the circle and the angle of point i, determine the relative position of point i with respect to the center of the circle, and thus obtain the coordinates (x, y) of point i. i ,y i ):

[0019] x i =x_center+Dcos(each_angle) / 2;

[0020] y i =y_center+Dsin(each_angle) / 2

[0021] Connect all the points in sequence to form the boundary of the random polygon in the current layer;

[0022] Step 4.2: The thickness of the old mortar layer is generated randomly and non-uniformly;

[0023] A certain amount of old mortar adheres to the surface of the recycled coarse aggregate, and this old mortar randomly wraps around the old interface layer of the natural aggregate. Let the virtual circle containing all vertices of the polygonal old interface layer be the inner circle of the aggregate, and the virtual circle containing all vertices of the polygonal old mortar layer be the outer circle of the aggregate. Based on step 4.1, different numbers of points n1 and n2 are randomly generated on the outer and inner circles of the aggregate, respectively. Then, random polygons are formed based on the points in n1 and n2, respectively, to create a non-uniform old mortar layer. To avoid the geometric boundaries of the random polygons on the outer and inner circles overlapping due to the insufficient thickness of the old mortar layer, the following measures are taken... The following method is used: First, construct a random polygon with n1 points on the outer circle, and assign vertex numbers 0, 1, 2, 3, ..., i, ..., j, ..., n1-1 to the polygon. Connect these points to form the random polygon on the outer circle as the outer boundary of the old mortar layer. Next, construct a random polygon on the inner circle. Based on the point numbers and positions of the outer polygon, randomly extract a point at intervals of 0 to 2 points, and then connect these points to form a random polygon on the inner circle as the inner boundary of the old mortar layer. Using this method, not only is a non-uniform old mortar layer constructed, but conflicts in polygon geometric boundaries are also absolutely avoided. See details below. Figure 2 ;

[0024] Step 5, set different replacement rates for recycled coarse aggregate:

[0025] Based on the recycled coarse aggregate replacement rate r of the fiber-reinforced recycled concrete to be simulated, calculate the (D) for each particle size range according to step 2. i D jThe number of recycled coarse aggregates and natural coarse aggregates is calculated, and the result is rounded down using a rounding function: int(r×n(D i D j )), n(D i D j )-int(r×n(D i D j The location and geometric information of recycled coarse aggregate and natural coarse aggregate need to be stored in different arrays, and the aggregate geometric parameters need to be set separately to determine the aggregate shape.

[0026] When the replacement rate is set to 1.0, all the aggregate is recycled coarse aggregate. The geometric parameters of the recycled coarse aggregate need to be set, including the thickness of the old mortar layer, the old mortar interface layer and the new mortar interface layer. For a single recycled coarse aggregate model, the thickness parameter is the difference in the radii of the circumcircle of the polygon.

[0027] When the replacement rate is set to 0, all the aggregate is natural coarse aggregate, and only the interface thickness between the natural aggregate and the new mortar needs to be set.

[0028] When the replacement rate is between 0 and 1, it is a mixture of recycled coarse aggregate and natural coarse aggregate, and the same thickness can be set for the natural aggregate interface and the new interface.

[0029] Step 6, establish the fiber-interface model, as follows:

[0030] A fiber model is introduced into the two-dimensional microscopic model. Considering the interaction between the fiber and the cement matrix, a fiber-cement matrix interface is set. The fiber model is set as a two-dimensional quadrilateral unit, and the geometric boundaries of the fiber and the fiber-cement matrix interface are separated. A certain thickness is uniformly extended outward around the fiber model to divide the interface and form the interface layer of the fiber-cement matrix.

[0031] Step 6.1, determine the coordinates of the geometric contour points of the fiber-interface model; such as Figure 3As shown, a fiber-interface model is generated using a "three-step decomposition method": First, a fiber-interface unit model is generated at the initial coordinate point ①, with the lower left corner of the model placed at the zero point of the xOy coordinate system. Second, a random counter-clockwise rotation angle is generated around the origin: angle = random.uniform(0, 2π), rotating the model to position ②. Third, a random translation distance along the x-axis: xlength = random.uniform(0, length) and a random translation distance along the y-axis: ylength = random.uniform(0, width) are generated, and the model is translated along the coordinate axes to position ③, thus completing the generation of one fiber-interface model. This method can easily generate fiber models that meet specific research needs. By adjusting the range of angle in the second step, the orientation of the fibers can be controlled, allowing for the study of the directional mechanism of the fibers. For example, setting angle = random.uniform(4π / 9, 5π / 9) will arrange the fiber length direction along the x-axis. See [link to documentation]. Figure 4 (a) By adjusting the translation distances xlength and ylength in step three, the position of the fiber model can be controlled, and the local reinforcement effect of the fiber on the entire model can be studied. See details. Figure 4 (b);

[0032] like Figure 3 As shown in position ③, based on the fiber length and diameter parameters and the fiber-cement interface thickness, the relative positions of the points are determined, and the coordinates of the four contour points of the fiber-interface model are finally generated:

[0033] A i =(thickness×sin(angle)+xlength,-thickness×cos(angle)+ylength);

[0034] B i =(-(thickness+fibre_l)×sin(angle)+xlength,(thickness+fibre_l)×cos(angle)+ylength);

[0035] C i =(thickness×sin(angle)+(2thickness+fibre_d)×cos(angle)+xlength,-thickness×cos(angle)+(2thickness+fibre_d)×sin(angle)+ylength);

[0036] Di =(-(thickness+fibre_l)×sin(angle)+(2thickness+fibre_d)×cos(angle)+xlength, (thickness+fibre_l)×cos(angle)+(2thickness+fibre_d)×sin(angle)+ylength);

[0037] Step 6.2: Determine whether there is overlap between fibers and aggregates, and between fibers; In the script, use the loop command for to repeat the fiber-interface model generation process in step 6.1. Each time the model is generated, check the overlap of the geometric boundaries of the model until a fiber-interface model with a quantity of fiber_n is generated.

[0038] To determine the overlap between fibers and aggregates as circles and rectangles, the following conditions must be met: all points of the outermost rectangle of the fiber-interface model must not be inside the outer circle of the aggregate, meaning the distance from each point to the center of the circle must be greater than the radius of the circle; at the same time, the distance from the center of the circle to each side of the rectangle must not be less than the radius of the circle.

[0039] To avoid fiber overlap (including boundary overlap), the contour points cannot simultaneously satisfy the following two formulas:

[0040]

[0041] In the formula, the subscripts 1 and 2 represent two different fibers.

[0042] Preferably, the method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete provided by the present invention may also have the following features: In step 3, the distribution characteristics of concrete aggregates are regarded as the random generation and placement of position coordinates, and the coordinates of the center points (x_center, y_center) of two-dimensional circular aggregates are randomly generated. The overlap between each pair of generated aggregates is judged, requiring that the distance between the centers be greater than the sum of the radii of the two circles; simultaneously, a protective layer of a certain thickness c is set around the concrete: c+D. <x_center<length-c-D,c+D<y_center<width-c-D。

[0043] Preferably, the method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete provided by the present invention may also have the following features: In step 5, geometric regions are divided for all microstructures using a cutting command. To facilitate the subsequent setting of section and element properties in ABAQUS, the location information of each phase structure is collected using the lookup function findat: myPart.faces.findAt(point). Then, a set is created for each microstructure, including: natural aggregate set_agg, natural interface set_itz1, new mortar set_newce, new mortar interface set_itz2, old mortar set_oldce, old mortar interface set_itz3, fiber set_fibre, and fiber-cement-based interface set_fibre_ce. For recycled concrete with different replacement rates r, the following relationship exists:

[0044] (1) If r≠0, then create set_itz2, set_oldce, and set_itz3;

[0045] (2) If r≠1, then create set_itz1;

[0046] (3) Regardless of the value of r, set_agg, set_newce, set_fibre, and set_fibre_ce are created.

[0047] The model generated by this invention is very simple. All microstructures are divided into geometric regions by the cutting command, and the findat function is used to create a set for each microstructure of the recycled concrete, which facilitates the subsequent setting of section properties and element properties.

[0048] Preferably, the method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete provided by the present invention may also have the following feature: In step 6, the geometric boundaries of the fibers and the fiber-cement matrix interface are separated using the ConstrainedSketch function command in ABAQUS:

[0049] mdb.models["Model-1"].ConstrainedSketch(name='sketch').Line(point1=(x1,y1),point2=(x2,y2));

[0050] In the script, point1 and point2 are both geometric boundary points of the fiber-interface model. The two points are connected by a straight line segmentation type Line. A certain thickness is uniformly extended outward around the fiber model, and the interface is divided again using function commands.

[0051] Preferably, the method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete provided by the present invention may also have the following features: In step 6, the fiber length fiber_l and fiber_d are set according to the information of the fiber-reinforced recycled concrete to be simulated, and the fiber volume content V is determined according to the fiber volume content V. f And the dimensions of the concrete, to calculate the number of fibers, fiber_n;

[0052] fiber_n = width × length × V f / fibre_l / fibre_d;

[0053] In the formula, width and length are the width and length of the two-dimensional plane model of the recycled concrete beam, respectively.

[0054] <System>

[0055] Furthermore, this invention also provides a system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete, capable of automatically implementing the above-mentioned <method>, characterized in that it includes:

[0056] Upon closer inspection of the model generation unit, a two-dimensional planar model of a recycled concrete beam with corresponding dimensions, shape, and position is generated based on the information of the fiber-reinforced recycled concrete to be simulated.

[0057] The aggregate calculation department calculates the number of recycled coarse aggregates within each particle size range based on the aggregate gradation of the two-dimensional plane model of the recycled concrete beam.

[0058] The aggregate location generation unit randomly generates the coordinates of the center point of the circular aggregate in the two-dimensional plane model of recycled concrete, and avoids overlap between aggregates.

[0059] The aggregate shape generation section uses the following steps 4.1 to 4.2 to randomly generate aggregate shapes in the two-dimensional plane model of recycled concrete;

[0060] Step 4.1, random generation of interlayer geometry:

[0061] A certain number of points are randomly generated on the virtual circular boundary line of the current layer. The number of points is a random integer within a given range. To determine the specific coordinates of the i-th point (i = 0, 1, 2, ..., n-1) on the circle with n points, the angle each_angle between point i and the x-axis is first randomly generated:

[0062] each_angle=random.uniform(2πi / n,2π(i+1) / n);

[0063] Next, based on the diameter D of the circle and the angle of point i, determine the relative position of point i with respect to the center of the circle, and thus obtain the coordinates (x, y) of point i. i ,y i ):

[0064] x i =x_center+Dcos(each_angle) / 2;

[0065] y i =y_center+Dsin(each_angle) / 2

[0066] Connect all the points in sequence to form the boundary of the random polygon in the current layer;

[0067] Step 4.2: The thickness of the old mortar layer is generated randomly and non-uniformly;

[0068] A certain amount of old mortar adheres to the surface of the recycled coarse aggregate, and this old mortar randomly wraps around the old interface layer of the natural aggregate. Let the virtual circle containing all vertices of the polygonal old interface layer be the inner circle of the aggregate, and the virtual circle containing all vertices of the polygonal old mortar layer be the outer circle of the aggregate. Based on step 4.1, different numbers of points n1 and n2 are randomly generated on the outer and inner circles of the aggregate, respectively. Then, random polygons are formed based on the points in n1 and n2, combining to form a non-uniform old mortar layer. To avoid the outer circle being randomly... The geometric boundaries of the polygon and the inner circle random polygon overlap and conflict. The following method is adopted: First, construct a random polygon with n1 points on the outer circle, and set the vertex numbers of the polygon to 0, 1, 2, 3, ..., i, ..., j, ..., n1-1. Connect these points to form the outer circle random polygon as the outer boundary of the old mortar layer. Then, construct a random polygon on the inner circle. According to the point number and position of the outer circle polygon, randomly extract a point at intervals of 0 to 2 points, and regenerate the inner circle random polygon as the inner boundary of the old mortar layer.

[0069] The replacement rate setting section sets different recycled coarse aggregate replacement rates: based on the given recycled coarse aggregate replacement rate r, and according to step 2, calculate the replacement rate for each particle size range (D). i ,D j The number of recycled coarse aggregates and natural coarse aggregates is calculated, and the result is rounded down using a rounding function: int(r×n(D i D j )), n(D i D j )-int(r×n(D i D jThe location and geometric information of recycled coarse aggregate and natural coarse aggregate need to be stored in different arrays, and the aggregate geometric parameters need to be set separately to determine the aggregate shape: When the replacement rate is set to 1.0, all the aggregate is recycled coarse aggregate, and the geometric parameters of the recycled coarse aggregate need to be set, including the thickness of the old mortar layer, the old mortar interface layer, and the new mortar interface layer; for a single recycled coarse aggregate model, the thickness parameter is the difference in the radius of the circumcircle of the polygon; when the replacement rate is set to 0, all the aggregate is natural coarse aggregate, and only the interface thickness between the natural aggregate and the new mortar needs to be set; when the replacement rate is between 0 and 1, the aggregate is a mixture of recycled and natural coarse aggregate, and the same thickness can be set for the natural aggregate interface and the new interface; different aggregate replacement rates are set only for the micro-model in the macro model, and the other parts of the macro model are homogeneous;

[0070] The fiber interface model construction section introduces a fiber model into the two-dimensional microscopic model. Considering the interaction between the fiber and the cement matrix, a fiber-cement matrix interface is set. The fiber model is set as a two-dimensional quadrilateral element, and the geometric boundaries of the fiber and the fiber-cement matrix interface are delineated. A certain thickness is uniformly extended outward around the fiber model to delineate the interface, forming the fiber-cement matrix interface layer. The following steps 6.1 and 6.2 are used to efficiently and accurately deliver the fiber:

[0071] Step 6.1, determine the coordinates of the geometric contour points of the fiber-interface model: First, generate the fiber-interface unit model at the initial coordinate point ①, with the lower left corner of the model placed at the zero point of the xOy coordinate system; Second, randomly generate the angle of counterclockwise rotation around the origin: angle = random.uniform(0, 2π), and rotate the model to position ②; Third, randomly generate the translation distance along the x-axis: xlength = random.uniform(0, length) and the translation distance along the y-axis: ylength = random.uniform(0, width), and translate the model along the coordinate axes to position ③, thus completing the generation of one fiber-interface model; By adjusting the range of angle in the second step, the orientation of the fiber can be controlled, and the directional action mechanism of the fiber can be studied; By adjusting the translation distances xlength and ylength in the third step, the generated position of the fiber model can be controlled, and the local reinforcement effect of the fiber on the entire model can be studied;

[0072] Based on the fiber length and diameter parameters, as well as the fiber-cement interface thickness, the relative positions of the points are determined, ultimately generating the coordinates of four contour points of the fiber-interface model:

[0073] A i=(thickness×sin(angle)+xlength,-thickness×cos(angle)+ylength);

[0074] B i =(-(thickness+fibre_l)×sin(angle)+xlength,(thickness+fibre_l)×cos(angle)+ylength);

[0075] C i =(thickness×sin(angle)+(2thickness+fibre_d)×cos(angle)+xlength,-thickness×cos(angle)+(2thickness+fibre_d)×sin(angle)+ylength);

[0076] D i =(-(thickness+fibre_l)×sin(angle)+(2thickness+fibre_d)×cos(angle)+xlength, (thickness+fibre_l)×cos(angle)+(2thickness+fibre_d)×sin(angle)+ylength);

[0077] Step 6.2: Determine whether there is overlap between fibers and aggregates, and between fibers; repeat the fiber-interface model generation process in step 6.1, and check the overlap of the geometric boundaries of the model each time it is generated, until a fiber-interface model with a quantity of fiber_n is generated.

[0078] To determine the overlap between fibers and aggregates as circles and rectangles, the following conditions must be met: all points of the outermost rectangle of the fiber-interface model must not be inside the outer circle of the aggregate; at the same time, the distance from the center of the circle to each side of the rectangle must not be less than the radius of the circle.

[0079] To avoid overlapping between fibers, the contour points cannot simultaneously satisfy the following two formulas:

[0080]

[0081] In the formula, the subscripts 1 and 2 represent two different fibers;

[0082] The control unit is connected in communication with the microscopic model generation unit, aggregate calculation unit, aggregate position generation unit, aggregate shape generation unit, replacement rate setting unit, and fiber interface model construction unit, and controls their operation.

[0083] Preferably, the system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete provided by the present invention may further include: an input display unit, communicatively connected to the control unit, for allowing users to input operation commands and displaying them accordingly. Through the graphical user interface of the input display unit, users can intuitively and quickly operate the generation and viewing of the model. The model parameters are highly adjustable and have a wide range of applications: from the material level to the component level; from ordinary concrete to recycled concrete.

[0084] Preferably, the system for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete provided by the present invention may also have the following features: in the aggregate position generation section, the distribution characteristics of concrete aggregates are regarded as the random generation and placement of position coordinates, and the coordinates of the center points (x_center, y_center) of two-dimensional circular aggregates are randomly generated. The overlap between each pair of generated aggregates is judged, requiring that the distance between the centers be greater than the sum of the radii of the two circles; simultaneously, a protective layer of a certain thickness c is set around the concrete: c+D. <x_center<length-c-D,c+D<y_center<width-c-D。

[0085] Preferably, the system for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete provided by the present invention may also have the following features: In the replacement rate setting section, the location information of each phase structure is collected using the lookup function findat: myPart.faces.findAt(point), and then a set is created for each phase microstructure, including: natural aggregate set_agg, natural interface set_itz1, new mortar set_newce, new mortar interface set_itz2, old mortar set_oldce, old mortar interface set_itz3, fiber set_fibre, and fiber-cement-based interface set_fibre_ce; for recycled concrete under different replacement rates r, the following relationship exists:

[0086] (1) If r≠0, then create set_itz2, set_oldce, and set_itz3;

[0087] (2) If r≠1, then create set_itz1;

[0088] (3) Regardless of the value of r, set_agg, set_newce, set_fibre, and set_fibre_ce are created.

[0089] Preferably, the system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete provided by the present invention may also have the following feature: in the fiber interface model construction section, the geometric boundaries of the fibers and the fiber-cement matrix interface are separated using the ConstrainedSketch function command in ABAQUS:

[0090] mdb.models["Model-1"].ConstrainedSketch(name='sketch').Line(point1=(x1,y1),point2=(x2,y2));

[0091] In the script, point1 and point2 are both geometric boundary points of the fiber-interface model. The two points are connected by a straight line segmentation type Line. A certain thickness is uniformly extended outward around the fiber model, and the interface is divided again using function commands.

[0092] The role and effect of invention

[0093] 1) This invention takes into account all the microstructures and interfaces of the model in detail. The recycled concrete contains a 6-phase structure, and after the fiber is inserted, it contains an 8-phase structure.

[0094] 2) In the recycled coarse aggregate model established in this invention, the old mortar is non-uniformly wrapped on the surface of the natural aggregate, and the thickness of the old mortar layer is not uniform, which is more consistent with the actual situation of recycled coarse aggregate.

[0095] 3) This invention establishes a micro-random aggregate model for fiber-reinforced recycled concrete under different replacement rates. The replacement rate can be set to any value between 0 and 1 according to the actual situation, and is not limited to 0 or 1. It takes into account all micro-phase structures inside the recycled concrete in a refined manner. The parameters of coarse aggregate, fiber and interface can be set according to specific scientific problems to carry out multi-scale numerical calculation and analysis.

[0096] 4) This invention uses a two-dimensional quadrilateral shell element as the fiber model and considers the fiber-cement-based interface within the two-dimensional model. To precisely control the position and orientation of the fiber-interface model, a three-step decomposition method is used for the first time to generate the fiber-interface model. This method can easily generate fiber models that meet specific research needs. On the one hand, by adjusting the range of the angle in the second step, the orientation of the fiber can be controlled to study the directional mechanism of the fiber. On the other hand, by adjusting the translation distances xlength and ylength in the third step, the generated position of the fiber model can be controlled to study the local reinforcement effect of the fiber on the entire model. This is of great significance for studying the directional mechanism of fibers.

[0097] 5) In the fiber-reinforced recycled concrete two-dimensional microscopic model generation method proposed in this invention, the special fiber generation and overlap judgment method can quickly generate and accurately judge the model. When the number of fibers is small, the fibers will not be over-concentrated due to the "laziness" of the random function command. When the number of fibers is large, it can also ensure that the fibers are inserted at appropriate angles and relative positions, achieving both high placement rate and high quality. It can achieve good results when the number of fibers is large or small.

[0098] 6) The present invention has simple operation steps, reasonable design, convenient implementation, good use effect, and low investment cost. Moreover, the rapid generation of fiber-reinforced recycled concrete two-dimensional multi-scale model established by the present invention has a short calculation time and can be well applied to numerical simulation (e.g., hierarchical calculation and analysis of recycled concrete components). Attached Figure Description

[0099] Figure 1 The flowchart is a method for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete according to the present invention.

[0100] Figure 2 This is a schematic diagram of the random system generation and overlap judgment algorithm of recycled coarse aggregate involved in the present invention; the recycled concrete contains natural coarse aggregate and recycled coarse aggregate, and there is a natural interface between the natural coarse aggregate and the new mortar; the recycled coarse aggregate consists of the following layers from the inside out: natural aggregate, old interface, old mortar, new interface, and the outermost layer is new mortar.

[0101] Figure 3 This is a schematic diagram of the "three-step decomposition method" for fiber-interface modeling involved in this invention;

[0102] Figure 4 This is a schematic diagram illustrating the beneficial effects of the "three-step decomposition method" involved in this invention, wherein (a) controls the fiber length direction to be arranged along the x-axis as a whole, and (b) controls the fiber model generation position (local generation);

[0103] Figure 5 This is a schematic diagram of the fiber-interface model overlap determination algorithm involved in the present invention;

[0104] Figure 6 This is a schematic diagram illustrating the beneficial effects of the fiber-interface model overlap judgment algorithm involved in this invention;

[0105] Figure 7 This invention relates to a GUI (Graphical User Interface).

[0106] Figure 8 This is a two-dimensional multi-scale model of a fiber-reinforced recycled concrete beam with a 100% recycled coarse aggregate replacement rate and a fiber volume content of 1.0%, as described in Embodiment 1 of the present invention.

[0107] Figure 9 This is a two-dimensional planar model of a standard cube of (fiber-reinforced) recycled concrete with a 100% recycled coarse aggregate replacement rate and different fiber volume fractions (0, 1.0%, 2.0%) according to Embodiment 2 of the present invention. Among them, (a) is a replacement rate of 100% and fiber fraction of 0; (b) is a replacement rate of 100% and fiber fraction of 1.0%; (c) is a replacement rate of 100% and fiber fraction of 2.0%.

[0108] Figure 10 This is a two-dimensional planar model of a standard prism of fiber-reinforced (recycled) concrete with a fiber volume content of 1.0% and different recycled coarse aggregate replacement rates (0 and 50%) according to Embodiment 3 of the present invention, wherein (a) is a replacement rate of 0 and a fiber content of 1.0%; and (b) is a replacement rate of 50% and a fiber content of 1.0%. Detailed Implementation

[0109] The following describes in detail, with reference to the accompanying drawings, the specific implementation scheme of the method and system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete according to the present invention.

[0110] <Example 1>

[0111] The purpose of this first embodiment is to generate a two-dimensional multi-scale model of a fiber-reinforced recycled concrete beam with a 100% recycled coarse aggregate replacement rate and a fiber volume content of 1.0%.

[0112] 1) Based on the given recycled coarse aggregate parameters, fiber parameters and the geometric dimensions of the recycled concrete beam, generate a two-dimensional planar model of the (fiber reinforced) recycled concrete beam. The planar dimensions of the beam model are 1250mm×250mm. At the middle part of the beam, 400mm, use the Monte Carlo method to generate a two-dimensional mesoscopic random aggregate model of (fiber reinforced) recycled concrete, and set the replacement rate of recycled coarse aggregate to 100%.

[0113] 2) Establish the geometric model of recycled coarse aggregate and fiber-interface, as follows:

[0114] Aggregate gradation parameters were set based on the Varavan aggregate gradation formula. The aggregate was continuously gradable, and the total aggregate volume fraction was set to 0.75, a commonly used value for continuous gradation. The particle size range of recycled coarse aggregate was 5–35 mm. The difference in radius of the circumscribed concentric circles was used as the interface and the geometric thickness of the mortar. The old mortar interface and the new mortar interface were both set to 0.5 mm, and the old mortar thickness was set to 1.0 mm. Next, the geometric parameters of the fibers and cohesive units were set, with a fiber length of 20 mm, a fiber diameter of 0.2 mm, and an aspect ratio of 100. Based on the fiber volume fraction, geometric parameters, and mesoscopic region size, the number of fibers was calculated to be 250. The cohesive region thickness was set to 0.05 mm, uniformly distributed around the fibers. All structures were geometrically delineated using a cutting command. The generated results are shown below. Figure 8 As shown.

[0115] <Example 2>

[0116] The purpose of this second embodiment is to generate standard cubic planar models of (fiber-reinforced) recycled concrete with a 100% recycled coarse aggregate replacement rate and three different fiber volume fractions: 0%, 1.0%, and 2.0%. When the fiber volume fraction is set to 0, a fiber-free recycled concrete model is generated, which is a special case of the method of this invention.

[0117] 1) Based on the given recycled coarse aggregate parameters and fiber parameters, generate a two-dimensional planar model of a standard cube of (fiber reinforced) recycled concrete. The model size is 150mm×150mm, and the replacement rate of recycled coarse aggregate is set to 100%.

[0118] 2) Establish the geometric model of recycled coarse aggregate and fiber-interface, as follows:

[0119] Aggregate gradation parameters were set based on the Varavan aggregate gradation formula. The aggregate was continuously gradable, and the total aggregate volume fraction was set to 0.75, a commonly used value for continuous gradation. The particle size range of recycled coarse aggregate was 5–20 mm. The interface between old and new mortar was set to 0.5 mm, and the thickness of the old mortar was set to 1.0 mm. Next, the geometric parameters of the fibers and cohesive units were set, with a fiber length of 14 mm, a fiber diameter of 0.2 mm, and an aspect ratio of 70. Based on the fiber volume fraction, geometric parameters, and mesoscopic region size, the number of fibers at each volume fraction was calculated to be 0, 80, and 160, respectively. The cohesive region thickness was set to 0.05 mm, uniformly distributed around the fibers. The generated results are shown below. Figure 9 As shown.

[0120] <Example 3>

[0121] The purpose of this third embodiment is to generate two-dimensional planar models of standard prisms of fiber-reinforced (recycled) concrete with a fiber volume content of 1.0% and different recycled coarse aggregate replacement rates. The recycled coarse aggregate replacement rates are 0% and 50%, respectively. In the models, recycled coarse aggregate is mixed with natural coarse aggregate, which can be used for numerical simulation studies of the material layers of fiber-reinforced (recycled) concrete. When the recycled coarse aggregate replacement rate is 0%, a normal concrete model will be generated, which is another special case of the method of this invention.

[0122] 1) A two-dimensional mesoscopic random aggregate model of fiber-reinforced (recycled) concrete was generated using the Monte Carlo method, with dimensions of 150mm × 300mm, which is the planar dimensions of a standard prism.

[0123] 2) Establish the geometric model of recycled coarse aggregate and fiber-interface, as follows:

[0124] Aggregate gradation parameters were set based on the Varavan aggregate gradation formula. The aggregate was continuously gradable, with the total aggregate volume fraction set to 0.75 (a commonly used value for continuous gradation). The coarse aggregate particle size range was 5–20 mm. The interfaces between the old and new mortars were both set to 0.5 mm, with the old mortar thickness set to 1.0 mm. The natural aggregate interface thickness was always consistent with the new mortar interface thickness, also set to 0.5 mm. Based on the recycled coarse aggregate replacement rate, the number of recycled and natural coarse aggregates within each particle size range was calculated. Next, the geometric parameters of the fibers and cohesive units were set. The fiber length was set to 12 mm, the fiber diameter to 0.2 mm, and the fiber aspect ratio to 60. Based on the fiber volume fraction, geometric parameters, and the microscopic model dimensions of the recycled concrete, the number of fibers was calculated to be 188. The cohesive region thickness was set to 0.05 mm, uniformly distributed around the fibers. The generated results are shown below. Figure 10 As shown.

[0125] <Example 4>

[0126] In this fourth embodiment, a system is provided that can automatically generate a two-dimensional multi-scale model of fiber-reinforced recycled concrete using the method of the present invention. The system includes a microscopic model generation unit, an aggregate calculation unit, an aggregate position generation unit, an aggregate shape generation unit, a replacement rate setting unit, a fiber interface model construction unit, an input display unit, and a control unit.

[0127] The micro-model generation unit performs the steps described in step 1 above, and generates a two-dimensional planar micro-model of recycled concrete with corresponding size, shape and position in the corresponding area of ​​the macro model of the concrete component, based on the information of the fiber-reinforced recycled concrete to be simulated.

[0128] The aggregate calculation department performs the steps described in step 2 above, and calculates the number of recycled coarse aggregates in each particle size range based on the aggregate gradation of the two-dimensional plane model of the recycled concrete beam.

[0129] The aggregate position generation unit performs the steps described in step 3 above, randomly generating the coordinates of the center point of the circular aggregate in the microscopic model, and avoiding overlap between aggregates;

[0130] The aggregate shape generation unit performs the steps described in step 4 above, randomly generating aggregate shapes in the microscopic model.

[0131] The replacement rate setting section performs the steps described in step 5 above to set different replacement rates for recycled coarse aggregate.

[0132] The fiber interface model construction unit performs the steps described in step 6 above, introduces the fiber model into the micro-model, sets the fiber-cement matrix interface considering the interaction between the fiber and the cement matrix, forms the interface layer of the fiber-cement matrix, and efficiently and accurately delivers the fiber.

[0133] The input display unit is used to allow users to input operation commands and displays the corresponding information. For example, the input and output data and processing procedures of each unit are displayed in the form of text, tables, or static or dynamic graphs.

[0134] The control unit is communicatively connected to the microscopic model generation unit, aggregate calculation unit, aggregate position generation unit, aggregate shape generation unit, replacement rate setting unit, fiber interface model construction unit, and input display unit, and controls their operation.

[0135] The above embodiments are merely illustrative examples of the technical solutions of the present invention. The method and system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete involved in the present invention are not limited to the content described in the above embodiments, but are defined by the scope of the claims. Any modifications, additions, or equivalent substitutions made by those skilled in the art based on these embodiments are within the scope of protection claimed by the claims of the present invention.

Claims

1. A method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete, characterized in that, Includes the following steps: Step 1: Based on the information of the fiber-reinforced recycled concrete to be simulated, generate a two-dimensional planar micro-model of the recycled concrete with corresponding size, shape, and position in the corresponding area of ​​the macro model of the concrete component. Step 2: Based on the aggregate gradation of the microstructure model, calculate the aggregate size range within each particle size range. D i , D j Number of recycled coarse aggregates n ( D i , D j ); Step 3: Randomly generate the coordinates of the center point of the circular aggregate in the microscopic model. x_center , y_center Position the aggregates carefully and avoid overlapping between them. Step 4: Randomly generate aggregate shapes in the microscopic model; including the following sub-steps: Step 4.1, random generation of interlayer geometry: A certain number of points are randomly generated on the virtual circular boundary line of the current layer. The number of points is a random integer within a given range. This is to determine the boundaries of the area with... n On the circle with point n, the first i The specific coordinates of each point i =0,1,2,…, n -1, first randomly generate points i and x Angle of axis each_angle : ； Next, based on the diameter of the circle D and points i By determining the angle and the relative position of a point with respect to the center of the circle, we can obtain the point's position. i coordinates ( x i , y i ): ； Connect all the points in sequence to form the boundary of the random polygon in the current layer; Step 4.2: The thickness of the old mortar layer is generated randomly and non-uniformly; A certain amount of old mortar adheres to the surface of the recycled coarse aggregate, and this old mortar randomly wraps around the old interface layer of the natural aggregate. Let the virtual circle containing all the vertices of the polygonal old interface layer be the inner circle of the aggregate, and the virtual circle containing all the vertices of the polygonal old mortar layer be the outer circle of the aggregate. Based on step 4.1, different numbers of points are randomly generated on the outer and inner circles of the aggregate, respectively. n 1 and n 2, and then, based on respectively n 1 and n The points in section 2 form random polygons, which combine to form a non-uniform old mortar layer. To avoid the geometric boundaries of the outer and inner random polygons overlapping due to the insufficient thickness of the old mortar layer, the following method is adopted: first construct on the outer circle... n A random polygon with one vertex, where the vertices are numbered 0, 1, 2, 3, ... i , …, j , …, n 1-1. Connect these points to form an outer circle random polygon as the outer boundary of the old mortar layer; then, construct a random polygon on the inner circle, and extract a point at random intervals of 0 to 2 points according to the number and position of the points of the outer circle polygon, and regenerate these points to form an inner circle random polygon as the inner boundary of the old mortar layer. Step 5, set different replacement rates for recycled coarse aggregate: Based on the recycled coarse aggregate replacement rate of the fiber-reinforced recycled concrete to be simulated r Based on step 2, calculate the particle size range for each particle size range. D i , D j The number of recycled coarse aggregates and natural coarse aggregates, and the integer part of the calculation result is rounded using a rounding function: int ( r × n ( D i , D j )), n ( D i , D j )- int ( r × n ( D i , D j The location and geometric information of recycled coarse aggregate and natural coarse aggregate need to be stored in different arrays, and the aggregate geometric parameters need to be set separately to determine the aggregate shape. When the replacement rate is set to 1.0, all the aggregate is recycled coarse aggregate. The geometric parameters of the recycled coarse aggregate need to be set, including the thickness of the old mortar layer, the old mortar interface layer and the new mortar interface layer. For a single recycled coarse aggregate model, the thickness parameter is the difference in the radii of the circumcircle of the polygon. When the replacement rate is set to 0, all the aggregate is natural coarse aggregate, and only the interface thickness between the natural aggregate and the new mortar needs to be set. When the replacement rate is between 0 and 1, it is a mixture of recycled coarse aggregate and natural coarse aggregate, and the same thickness can be set for the natural aggregate interface and the new interface. Step 6, establish the fiber-interface model, as follows: In a micro-modeling approach, a fiber model is introduced. Considering the interaction between the fiber and the cementitious matrix, a fiber-cement-matrix interface is established. The fiber model is set as a two-dimensional quadrilateral element, and the geometric boundaries of the fiber and the fiber-cement-matrix interface are delineated. A certain thickness is uniformly extended outward around the fiber model. thickness The interface is defined to form an interface layer of fiber-cement matrix; Step 6.1, determine the coordinates of the geometric contour points of the fiber-interface model: First, generate the fiber-interface element model at the initial coordinate point ①, with the lower left endpoint of the model placed at... xOy The first step is to establish the origin of the coordinate system; the second step is to randomly generate the angle of counterclockwise rotation around the origin. angle = random.uniform (0, 2π), rotate the model to position ②; third step, randomly generate along... x Translation distance of the axis: xlength = random.uniform (0 , length ) and along y Translation distance of the axis: ylength = random.uniform (0 , width The model is then translated along the coordinate axes to position ③, thus completing the generation of a fiber-interface model. width and length These represent the width and length of the two-dimensional planar model of the recycled concrete beam, respectively; by adjusting the second step... angle The range of fiber orientation can be controlled to study the mechanism of fiber directionality. By adjusting the translation distance in step three xlength and ylength It can control the fiber model generation location and study the local reinforcement effect of fibers on the entire model; Based on the fiber length and diameter parameters and the fiber-cement interface thickness thickness The relative positions of the points are determined, and the coordinates of the four contour points of the fiber-interface model are finally generated: A i =( thickness ×sin( angle )+ xlength , - thickness ×cos( angle )+ ylength ); B i =(-( thickness + fiber_l )×sin( angle )+ xlength , ( thickness + fiber_l )×cos( angle )+ ylength ); C i =( thickness ×sin( angle )+(2 thickness + fiber_d )×cos( angle )+ xlength , - thickness ×cos( angle )+ (2 thickness + fiber_d )×sin( angle )+ ylength ); D i =(-( thickness + fiber_l )×sin( angle )+(2 thickness + fiber_d )×cos( angle )+ xlength , ( thickness + fiber_l ) ×cos( angle )+ (2 thickness + fiber_d )×sin( angle )+ ylength ); In the formula, fiber_l For the length of the fiber, fiber_d The diameter of the fiber; Step 6.2: Determine whether there is overlap between fibers and aggregates, and between fibers themselves; repeat the fiber-interface model generation process from step 6.1, checking the overlap of the geometric boundaries of the model each time it is generated, until the required number of overlaps is met. fibre_n Fiber-interface model; To determine the overlap between fibers and aggregates as circles and rectangles, the following conditions must be met: all points of the outermost rectangle of the fiber-interface model must not be inside the outer circle of the aggregate; at the same time, the distance from the center of the circle to each side of the rectangle must not be less than the radius of the circle. To avoid overlapping between fibers, the contour points cannot simultaneously satisfy the following two formulas: ； In the formula, the subscripts 1 and 2 represent two different fibers.

2. The method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete according to claim 1, characterized in that: in, In step 3, the distribution characteristics of concrete aggregates are considered as the random generation and placement of position coordinates, and the coordinates of the center point of the two-dimensional circular aggregates are randomly generated ( x_center , y_center The process involves checking for overlap between each pair of generated aggregates, ensuring that the distance between the centers of the two circles is greater than the sum of their radii; simultaneously, a certain thickness is set around the concrete perimeter. c Protective layer: c+D <x_center<length-c-D , c+D < y_center <width-c-D .

3. The method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete according to claim 1, characterized in that: in, In step 5, a lookup function is used. findat Collect the location information of each phase structure: myPart.faces.findAt(point), and then create a set for each phase microstructure. set Including: natural aggregates set_agg Natural Interface Collection set_itz 1. New mortar aggregate set_newce New mortar interface set set_itz2 Old mortar collection set_oldce Old mortar interface collection set_itz3 Fiber aggregate set_fibre Fiber-cement-based interface set_ fiber_ce Set; for different substitution rates r The following relationship exists for recycled concrete: (1) If r If ≠0, then create set_itz2, set_oldce, set_itz3; (2) If r If ≠1, then create set_itz 1; (3) Regardless r For how many, create set_agg, set_newce, set_fibre, set_fibre_ce .

4. The method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete according to claim 1. Its features are: In step 6, functions in ABAQUS are used. ConstrainedSketch The geometric boundaries of the fiber and the fiber-cement interface are delineated: mdb.models [" Model-1 "] ConstrainedSketch ( name='sketch' ) .Line ( point 1 = ( x 1 , y 1) ,point 2 = ( x 2 , y 2))； In the script, point 1 and point Both points are geometric boundary points of the fiber-interface model, and are connected by a straight line segmentation type Line. A certain thickness is uniformly extended outward around the fiber model. thickness And then use function commands again to divide the interface.

5. The method for rapidly generating a two-dimensional multi-scale model of fiber-reinforced recycled concrete according to claim 1, characterized in that: in, In step 6, the fiber length is set according to the information of the fiber-reinforced recycled concrete to be simulated. fiber_l and diameter fiber_d And based on the fiber volume fraction V f And the dimensions of the concrete, to calculate the number of fibers. fiber n ; 。 6. A system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete, characterized in that, include: The micro-model generation unit generates a two-dimensional planar micro-model of recycled concrete with corresponding size, shape, and position in the corresponding area of ​​the macro model of the concrete component, based on the information of the fiber-reinforced recycled concrete to be simulated. The aggregate calculation department calculates the aggregate gradation within each particle size range based on the two-dimensional plane model of the recycled concrete beam. D i , D j Number of recycled coarse aggregates n ( D i , D j ); The aggregate location generation unit randomly generates the coordinates of the center point of the circular aggregate in the microscopic model. x_center , y_center Position the aggregates carefully and avoid overlapping between them. The aggregate shape generation section uses the following steps 4.1~4.2 to randomly generate aggregate shapes in the microscopic model; Step 4.1, random generation of interlayer geometry: A certain number of points are randomly generated on the virtual circular boundary line of the current layer. The number of points is a random integer within a given range. This is to determine the boundaries of the area with... n On the circle with point n, the first i The specific coordinates of each point i =0,1,2,…, n -1, first randomly generate points i and x Angle of axis each_angle : ； Next, based on the diameter of the circle D and points i By determining the angle and the relative position of a point with respect to the center of the circle, we can obtain the point's position. i coordinates ( x i , y i ): ； Connect all the points in sequence to form the boundary of the random polygon in the current layer; Step 4.2: The thickness of the old mortar layer is generated randomly and non-uniformly; A certain amount of old mortar adheres to the surface of the recycled coarse aggregate, and this old mortar randomly wraps around the old interface layer of the natural aggregate. Let the virtual circle containing all the vertices of the polygonal old interface layer be the inner circle of the aggregate, and the virtual circle containing all the vertices of the polygonal old mortar layer be the outer circle of the aggregate. Based on step 4.1, different numbers of points are randomly generated on the outer and inner circles of the aggregate, respectively. n 1 and n 2, and then, based on respectively n 1 and n The points in section 2 form random polygons, which combine to form a non-uniform old mortar layer. To avoid the geometric boundaries of the outer and inner random polygons overlapping due to the insufficient thickness of the old mortar layer, the following method is adopted: first construct on the outer circle... n A random polygon with one vertex, where the vertices are numbered 0, 1, 2, 3, ... i , …, j , …, n 1-1. Connect these points to form an outer circle random polygon as the outer boundary of the old mortar layer; then, construct a random polygon on the inner circle, and extract a point at random intervals of 0 to 2 points according to the number and position of the points of the outer circle polygon, and regenerate these points to form an inner circle random polygon as the inner boundary of the old mortar layer. The replacement rate setting section allows you to set different recycled coarse aggregate replacement rates: based on a given recycled coarse aggregate replacement rate... r Based on step 2, calculate the values ​​for each particle size range. D i , D j The number of recycled coarse aggregates and natural coarse aggregates, and the integer part of the calculation result is rounded using a rounding function: int ( r × n ( D i , D j )), n ( D i , D j )- int ( r × n ( D i , D j The location and geometric information of recycled coarse aggregate and natural coarse aggregate need to be stored in different arrays, and the aggregate geometric parameters need to be set separately to determine the aggregate shape: When the replacement rate is set to 1.0, all of them are recycled coarse aggregate, and the geometric parameters of recycled coarse aggregate need to be set, including the thickness of the old mortar layer, the old mortar interface layer and the new mortar interface layer; for a single recycled coarse aggregate model, the thickness parameter is the difference in the radius of the circumcircle of the polygon; when the replacement rate is set to 0, all of them are natural coarse aggregate, and only the interface thickness between natural aggregate and new mortar needs to be set; when the replacement rate is between 0 and 1, it is a mixture of recycled coarse aggregate and natural coarse aggregate, and the same thickness can be set for the natural aggregate interface and the new interface. In the fiber interface model construction section, a fiber model is introduced into the microscopic model. Considering the interaction between the fiber and the cementitious matrix, a fiber-cement-matrix interface is set. The fiber model is set as a two-dimensional quadrilateral element, and the geometric boundaries of the fiber and the fiber-cement-matrix interface are delineated. A certain thickness is uniformly extended outward around the fiber model. thickness The interface is then defined to form a fiber-cement matrix interface layer; the following steps 6.1 and 6.2 are used for efficient and accurate fiber delivery: Step 6.1, determine the coordinates of the geometric contour points of the fiber-interface model: First, generate the fiber-interface element model at the initial coordinate point ①, with the lower left endpoint of the model placed at... xOy The first step is to establish the origin of the coordinate system; the second step is to randomly generate the angle of counterclockwise rotation around the origin. angle = random.uniform (0, 2π), rotate the model to position ②; third step, randomly generate along... x Translation distance of the axis: xlength = random.uniform (0 , length ) and along y Translation distance of the axis: ylength = random.uniform (0 , width The model is then translated along the coordinate axes to position ③, thus completing the generation of a fiber-interface model. width and length These represent the width and length of the two-dimensional planar model of the recycled concrete beam, respectively; by adjusting the second step... angle The range of fiber orientation can be controlled to study the mechanism of fiber directionality. By adjusting the translation distance in step three xlength and ylength It can control the fiber model generation location and study the local reinforcement effect of fibers on the entire model; Based on the fiber length and diameter parameters and the fiber-cement interface thickness thickness The relative positions of the points are determined, and the coordinates of the four contour points of the fiber-interface model are finally generated: A i =( thickness ×sin( angle )+ xlength , - thickness ×cos( angle )+ ylength ); B i =(-( thickness + fiber_l )×sin( angle )+ xlength , ( thickness + fiber_l )×cos( angle )+ ylength ); C i =( thickness ×sin( angle )+(2 thickness + fiber_d )×cos( angle )+ xlength , - thickness ×cos( angle )+ (2 thickness + fiber_d )×sin( angle )+ ylength ); D i =(-( thickness + fiber_l )×sin( angle )+(2 thickness + fiber_d )×cos( angle )+ xlength , ( thickness + fiber_l ) ×cos( angle )+ (2 thickness + fiber_d )×sin( angle )+ ylength ); In the formula, fiber_l For the length of the fiber, fiber_d The diameter of the fiber; Step 6.2: Determine whether there is overlap between fibers and aggregates, and between fibers themselves; repeat the fiber-interface model generation process from step 6.1, checking the overlap of the geometric boundaries of the model each time it is generated, until the required number of overlaps is met. fibre_n Fiber-interface model; To determine the overlap between fibers and aggregates as circles and rectangles, the following conditions must be met: all points of the outermost rectangle of the fiber-interface model must not be inside the outer circle of the aggregate; at the same time, the distance from the center of the circle to each side of the rectangle must not be less than the radius of the circle. To avoid overlapping between fibers, the contour points cannot simultaneously satisfy the following two formulas: ； In the formula, the subscripts 1 and 2 represent two different fibers; The control unit is communicatively connected to the microscopic model generation unit, the aggregate calculation unit, the aggregate position generation unit, the aggregate shape generation unit, the replacement rate setting unit, and the fiber interface model construction unit, and controls their operation.

7. The system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete according to claim 6, characterized in that, Also includes: The input display unit is communicatively connected to the control unit and is used to allow the user to input operation commands and display the corresponding commands.

8. The system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete according to claim 6, characterized in that: in, In the aggregate location generation unit, the distribution characteristics of concrete aggregates are considered as the random generation and placement of location coordinates, and the coordinates of the center point of the two-dimensional circular aggregate are randomly generated. x_center , y_center The process involves checking for overlap between each pair of generated aggregates, ensuring that the distance between the centers of the two circles is greater than the sum of their radii; simultaneously, a certain thickness is set around the concrete perimeter. c Protective layer: c+D <x_center<length-c-D , c+D < y_center <width-c-D .

9. The system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete according to claim 6, characterized in that: in, In the replacement rate setting section, a lookup function is used. findat Collect the location information of each phase structure: myPart.faces.findAt(point), and then create a set for each phase microstructure. set Including: natural aggregates set_agg Natural Interface Collection set_itz 1. New mortar aggregate set_newce New mortar interface set set_itz2 Old mortar collection set_oldce Old mortar interface collection set_itz3 Fiber aggregate set_fibre Fiber-cement-based interface set_ fiber_ce Set; for different substitution rates r The following relationship exists for recycled concrete: (1) If r If ≠0, then create set_itz2, set_oldce, set_itz3; (2) If r If ≠1, then create set_itz 1; (3) Regardless r For how many, create set_agg, set_newce, set_fibre, set_fibre_ce .

10. The system for rapidly generating two-dimensional multi-scale models of fiber-reinforced recycled concrete according to claim 6. Its features are: in, In the fiber interface model construction section, functions and commands in ABAQUS are used. ConstrainedSketch The geometric boundaries of the fiber and the fiber-cement interface are delineated: mdb.models [" Model-1 "] ConstrainedSketch ( name='sketch' ) .Line ( point 1 = ( x 1 , y 1) ,point 2 = ( x 2 , y 2))； In the script, point 1 and point Both points are geometric boundary points of the fiber-interface model, and are connected by a straight line segmentation type Line. A certain thickness is uniformly extended outward around the fiber model. thickness And then use function commands again to divide the interface.

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