Fiber random distribution RVE generation method and equipment based on lattice division

Abstract

The invention belongs to the related technical field of composite materials, and discloses a lattice division-based fiber random distribution RVE generation method and equipment, and the method comprises the following steps: (1) setting parameters of RVE, and calculating the size of an RVE window and the number of fibers required to be generated; the parameters comprise a target fiber volume fraction # imgabs0 # fiber radius rf, a lattice type and a normalized lattice side length alpha; (2) obtaining a fiber distribution of a first target fiber volume fraction by random fiber generation; (3) dividing the RVE window into periodic crystal lattices; (4) moving each current fiber to the nearest crystal lattice center; and (5) adding new fibers in the RVE window, and further completing generation of random distribution of the fibers. The method is simple in principle, few in input parameters, short in operation time and easy to program, and fiber distribution with the fiber volume fraction as high as 80% can be effectively generated.

Description

Technical Field

[0001] The present invention belongs to the technical field related to composite materials, and more specifically, relates to a method and device for generating a fiber random distribution RVE based on lattice division. Background Art

[0002] Continuous fiber reinforced composites have excellent properties of high specific strength and specific stiffness, and therefore have been widely used in the aerospace and rail transportation industries. In order to analyze and predict the performance of composite materials, many scholars have carried out a large number of experimental studies; however, experimental studies require a lot of time and manpower, and more efficient numerical simulation methods have gained favor among researchers in recent years. The representative volume element (RVE) method is an effective means to study the micromechanics of composite materials. In order to establish a reasonable RVE model, it is necessary to first determine the fiber distribution in the composite material. Existing studies have shown that the fibers in actual materials tend to be randomly distributed, and the RVE model with random fiber distribution can achieve more accurate prediction of composite material performance.

[0003] Existing methods for generating random fiber distribution can be divided into two categories. In the first method, fibers are gradually generated until the required volume fraction is reached, and certain constraints are used to control the sequential generation of fibers, such as the hard core method, random sequence expansion method, etc. The fiber volume fraction generated by this type of algorithm usually does not exceed 70%, and it is impossible to generate a random fiber distribution with a high fiber content. The process of the second method is to first randomly or uniformly generate the number of fibers with the required volume fraction (allowing fiber interference), and then control the movement of the fibers according to certain constraints to achieve the purpose of resolving fiber interference or improving the randomness of fiber distribution, such as the initial periodic vibration method, molecular dynamics method, etc. This type of method can generate a random fiber distribution with a higher fiber volume fraction, but the principle is more complicated and the running time is longer. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a method and device for generating RVE of random fiber distribution based on lattice division, which aims to solve the problem of low fiber content in the existing fiber distribution.

[0005] To achieve the above object, according to one aspect of the present invention, a method for generating a fiber random distribution RVE based on lattice partitioning is provided, the method comprising the following steps:

[0006] (1) Setting the parameters of RVE and calculating the size of the RVE window and the number of fibers to be generated; the parameters include the target fiber volume fraction Fiber radius r f , lattice type and normalized lattice edge length α;

[0007] (2) obtaining a fiber distribution having a first target fiber volume fraction by random fiber generation;

[0008] (3) Divide the RVE window into a periodic lattice;

[0009] (4) Move the current fibers to the nearest lattice center;

[0010] (5) Add new fibers in the RVE window to complete the generation of random fiber distribution.

[0011] Furthermore, step (1) includes the following sub-steps:

[0012] Step (1.1): Determine parameters including target fiber volume fraction Fiber radius r f , lattice type and normalized lattice side length α; the lattice types include regular hexagonal lattice and square lattice, and the normalized lattice side length represents the ratio of lattice length to fiber radius α = l 0 / r f ;

[0013] Step (1.2): Based on the parameters in step (1.1), the size of the RVE window and the number of fibers required to be generated can be calculated.

[0014] Furthermore, the length L and width W of the RVE window under hexagonal lattice division are:

[0015]

[0016] The length L and width W of the RVE window divided by a square lattice are:

[0017]

[0018] The number of fibers N that need to be generated tar for:

[0019]

[0020] Furthermore, step (2) includes the following sub-steps:

[0021] Step (2.1): Taking the center of the RVE window as the coordinate origin, randomly generate a new fiber F try =(x try ,y try ), x try =rand[-L / 2,L / 2],y try =rand[-W / 2,W / 2];

[0022] Step (2.2): Compare whether the fiber overlaps with the existing fiber. If so, go to step (2.1). If not, accept the fiber and determine whether the first target fiber volume fraction is reached. If so, end. If not, go to step (2.1).

[0023] Furthermore, the first target fiber volume fraction has a value range of 0 to 50%.

[0024] Furthermore, taking the center of the RVE window as the coordinate origin and the lower left vertex of the RVE window as the center of the first lattice, all lattice centers contained in the RVE window are calculated, and the RVE window is lattice-divided according to the lattice center coordinates.

[0025] Furthermore, step (4) includes the following sub-steps:

[0026] Step (4.1): Compare the distances between the fiber center and the centers of all the lattices to be matched, take the lattice with the closest distance as its closest lattice, and move the lattice out of the list of lattices to be matched. The moving direction of the fiber is set to the direction starting from the fiber center and ending at the center of the closest lattice;

[0027] Step (4.2): Calculate the maximum movable distance of the fiber when it moves along the moving direction

[0028] Step (4.3): Determine the maximum movable distance Is it greater than or equal to the movable distance threshold l? thre If so, the fiber movement distance is If not, the moving direction of the fiber is randomly specified and the process goes to step (4.2); wherein the fiber movable distance threshold l is also thre It is equal to the difference between the adjacent lattice centers and the fiber diameter.

[0029] Furthermore, step (5) includes the following sub-steps:

[0030] Step (5.1): Randomly generate new fibers F try =(x try ,y try ), x try =rand[-L / 2,L / 2],y try =rand[-W / 2,W / 2];

[0031] Step (5.2): Compare whether the fiber overlaps with the existing fiber. If so, go to step (5.1) until the maximum number of attempts is reached. When the number of attempts reaches the maximum number of attempts, go to step (4). If not, accept the fiber and determine whether the required number of fibers is reached. If so, the fiber generation is completed. If not, go to step (5.1).

[0032] The present invention also provides a fiber random distribution RVE generation system based on lattice partitioning, the system includes a memory and a processor, the memory stores a computer program, and the processor executes the fiber random distribution RVE generation method based on lattice partitioning as described above when executing the computer program.

[0033] The present invention also provides a computer-readable storage medium, which stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the fiber random distribution RVE generation method based on lattice partitioning as described above.

[0034] In general, compared with the prior art, the above technical solutions conceived by the present invention mainly have the following advantages over the prior art:

[0035] Beneficial effects:

[0036] 1. The present invention provides a method for generating RVE of random fiber distribution based on lattice partitioning. The method has a simple principle, few input parameters, short running time, and is easy to program and implement. It can effectively generate fiber distribution with a fiber volume fraction of up to 80%, and provides a simple and effective method for creating fiber distribution in numerical research on micromechanics of composite materials.

[0037] 2. The RVE window is divided into a periodic lattice, the current fibers are moved to the nearest lattice center, and then new fibers are added to the RVE window to complete the generation of random fiber distribution. This method is easy to implement, has strong practicality, and is conducive to promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of a fiber random distribution RVE generation method based on lattice partitioning provided by the present invention;

[0039] Figure 2 It is a randomly generated fiber distribution map with a fiber volume fraction of 50%;

[0040] Figure 3 is the regular hexagonal lattice division diagram of the RVE window;

[0041] Figure 4 is a schematic diagram of fiber movement;

[0042] Figure 5 is a schematic diagram of random fiber filling;

[0043] Figure 6This is the fiber distribution map generated by this method with a fiber volume fraction of 60%;

[0044] Figure 7 This is the fiber distribution map generated by this method with a fiber volume fraction of 80%. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] The present invention provides a method for generating a fiber random distribution RVE based on lattice partitioning, and the method mainly comprises the following steps:

[0047] (1) Setting the parameters of RVE and calculating the size of the RVE window and the number of fibers to be generated; the parameters include the target fiber volume fraction Fiber radius r f , lattice type and normalized lattice edge length α.

[0048] Step (1) includes the following sub-steps:

[0049] Step (1.1): Determine parameters including target fiber volume fraction Fiber radius r f , lattice type and normalized lattice side length α. The lattice types include regular hexagonal lattice and square lattice. The normalized lattice side length represents the ratio of lattice length to fiber radius α = l 0 / r f .

[0050] Step (1.2): Based on the parameters in step (1.1), the size of the RVE window and the number of fibers to be generated can be calculated: the length L and width W of the RVE window divided by a hexagonal lattice are:

[0051]

[0052] The length L and width W of the RVE window divided by a square lattice are:

[0053]

[0054] The number of fibers N that need to be generated tar for:

[0055]

[0056] (2) Obtaining a fiber distribution with a first target fiber volume fraction by random fiber generation.

[0057] Step (2) includes the following sub-steps:

[0058] Step (2.1): Taking the center of the RVE window as the coordinate origin, randomly generate a new fiber F try =(x try ,y try ), x try =rand[-L / 2,L / 2],y try =rand[-W / 2,W / 2];

[0059] Step (2.2): Compare whether the fiber overlaps with the existing fiber. If so, go to step (2.1). If not, accept the fiber and determine whether the first target fiber volume fraction is reached. If so, end. If not, go to step (2.1).

[0060] The first target fiber volume fraction has a value range of 0 to 50%.

[0061] (3) Divide the RVE window into a periodic lattice.

[0062] Specifically, the center of the RVE window is taken as the coordinate origin, the lower left vertex of the RVE window is taken as the center of the first lattice, all lattice centers contained in the RVE window are calculated, and the RVE window is divided into lattices according to the lattice center coordinates.

[0063] (4) Move the current fibers to the nearest lattice center.

[0064] Step (4) includes the following sub-steps:

[0065] Step (4.1): Compare the distances between the fiber center and the centers of all the lattices to be matched, take the lattice with the closest distance as its closest lattice, and move the lattice out of the list of lattices to be matched. The moving direction of the fiber is set to the direction starting from the fiber center and ending at the center of the closest lattice;

[0066] Step (4.2): Calculate the maximum movable distance of the fiber when it moves along the moving direction

[0067] Step (4.3): Determine the maximum movable distance Is it greater than or equal to the movable distance threshold l? thre If so, the fiber movement distance is If not, the fiber moving direction is randomly specified and go to step (4.2).

[0068] The fiber movable distance threshold l thre Equal to the difference between the adjacent lattice center and the fiber diameter, under the hexagonal lattice division In the square lattice division thre =αr f -2r f .

[0069] (5) Add new fibers in the RVE window to complete the generation of random fiber distribution.

[0070] Step (5) includes the following sub-steps:

[0071] Step (5.1): Randomly generate new fibers F try =(x try ,y try ), x try =rand[-L / 2,L / 2],y try =rand[-W / 2,W / 2];

[0072] Step (5.2): Compare whether the fiber overlaps with the existing fiber. If so, go to step (5.1) until the maximum number of attempts is reached. When the number of attempts reaches the maximum number of attempts, go to step (4). If not, accept the fiber and determine whether the required number of fibers is reached. If so, the fiber generation is completed. If not, go to step (5.1).

[0073] Normalized lattice edge length α vs. lattice type and target fiber volume fraction The specific relationship is as follows:

[0074] When the lattice type is regular hexagon,

[0075] When the lattice type is square,

[0076] The present invention also provides a fiber random distribution RVE generation system based on lattice partitioning, the system includes a memory and a processor, the memory stores a computer program, and the processor executes the fiber random distribution RVE generation method based on lattice partitioning as described above when executing the computer program.

[0077] The present invention also provides a computer-readable storage medium, which stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the fiber random distribution RVE generation method based on lattice partitioning as described above.

[0078] The present invention is further described in detail below with reference to specific embodiments.

[0079] like Figure 1 As shown in the figure, this example takes the simulation of generating a random fiber distribution with a fiber volume fraction of 60% as an example, and sets the input parameter to the target fiber volume fraction. Fiber radius r f =3.3μm, the lattice type is regular hexagon, the normalized lattice length α=1.1927, the calculated window size is L=163.6127μm, W=165.3082μm, and the number of fibers to be generated is N tar =474.

[0080] Set the first target fiber volume fraction to 50%. First, randomly generate the first fiber F 0 =(x 0 ,y 0 ), x 0 =rand[-L / 2,L / 2],y 0 =rand[-W / 2,W / 2]. Randomly generate new fiber F try =(x try ,y try ), x try =rand[-L / 2,L / 2],y try = rand[-W / 2, W / 2], compare whether the fiber overlaps with the existing fiber, if so, randomly generate new fibers and compare, if not, accept the fiber and determine whether the first target fiber volume fraction is reached, if yes, proceed to the next step, if not, randomly generate new fibers and compare. The fiber distribution generated by the random generation method is as follows Figure 2 shown.

[0081] Take the center of the RVE window as the coordinate origin, take the lower left vertex of the RVE window as the center of the first lattice, calculate all the lattice centers contained in the RVE window, and divide the RVE window into lattices according to the lattice center coordinates. In this example, there are 672 lattices in total. Figure 3 shown.

[0082] For each fiber in the window, compare the distance between the fiber center and the centers of all the lattices to be matched, take the lattice with the closest distance as its nearest lattice, and move the lattice out of the list of lattices to be matched. The direction of fiber movement starts from the fiber center and ends at the nearest lattice center. Calculate the maximum movable distance of the fiber when it moves along this direction Calculate the movable distance threshold l thre = 0.2172μm. Determine the maximum movable distance Is it greater than or equal to the movable distance threshold l? thre If so, the fiber movement distance is If not, the fiber movement direction is randomly specified and the maximum movable distance is recalculated until the maximum movable distance is greater than or equal to the movable distance threshold. Figure 4 As shown, the hollow circle represents the fiber position before movement, the solid circle represents the fiber position after movement, and the arrow represents the movement path of the fiber center.

[0083] After all fibers are moved, a new fiber F is randomly generated in the RVE window. try =(x try ,y try ), x try =rand[-L / 2,L / 2],y try = rand[-W / 2,W / 2]. Compare whether the fiber overlaps with the existing fiber. If so, try to generate a new fiber again until the maximum number of attempts is reached. If not, accept the fiber and determine whether the current number of fibers reaches the number of fibers that need to be generated. If so, fiber generation ends. If not, try to generate a new fiber and compare. Random fiber filling is as follows Figure 5 As shown, the hollow circles represent existing fibers, and the solid circles represent newly added fibers.

[0084] When the number of new fiber attempts reaches the maximum number of attempts, all fibers are moved again and new fibers are tried to be added. This process is repeated until the required number of fibers is reached. The fiber distribution with a fiber volume fraction of 60% is generated as follows: Figure 6 As shown, there are 474 fibers in total. There is no overlap between the generated fibers and their distribution is random, which proves the effectiveness of this method.

[0085] Other parameters remain unchanged, set the target fiber volume fraction The resulting fiber distribution of 80% fiber volume fraction is as follows Figure 7 As shown, there are 632 fibers in total, proving that the method can effectively generate a fiber distribution with a fiber volume fraction as high as 80%.

[0086] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fiber random distribution RVE generation method based on lattice partitioning, characterized by: The method comprises the following steps: (1) Setting the parameters of RVE and calculating the size of the RVE window and the number of fibers to be generated; the parameters include the target fiber volume fraction Fiber radius r f , lattice type and normalized lattice edge length α; (2) obtaining a fiber distribution having a first target fiber volume fraction by random fiber generation; (3) Divide the RVE window into a periodic lattice; (4) Move the current fibers to the nearest lattice center; (5) Add new fibers in the RVE window to complete the generation of random fiber distribution.

2. The fiber random distribution RVE generation method based on lattice partitioning according to claim 1, characterized in that: Step (1) includes the following sub-steps: Step (1.1): Determine parameters including target fiber volume fraction Fiber radius r f , lattice type and normalized lattice side length α; the lattice types include regular hexagonal lattice and square lattice, and the normalized lattice side length represents the ratio of lattice length to fiber radius α = l0 / r f ; Step (1.2): Based on the parameters in step (1.1), the size of the RVE window and the number of fibers required to be generated can be calculated.

3. The fiber random distribution RVE generation method based on lattice partitioning according to claim 2, characterized in that: The length L and width W of the RVE window divided by hexagonal lattice are: The length L and width W of the RVE window divided by a square lattice are: The number of fibers N that need to be generated tar for:

4. The fiber random distribution RVE generation method based on lattice partitioning according to claim 1 is characterized in that: Step (2) includes the following sub-steps: Step (2.1): Taking the center of the RVE window as the coordinate origin, randomly generate a new fiber F try =(x try ,y try ), x try =rand[-L / 2,L / 2],y try =rand[-W / 2,W / 2]; Step (2.2): Compare whether the fiber overlaps with the existing fiber. If so, go to step (2.1). If not, accept the fiber and determine whether the first target fiber volume fraction is reached. If so, end. If not, go to step (2.1).

5. The fiber random distribution RVE generation method based on lattice partitioning according to claim 4, characterized in that: The first target fiber volume fraction has a value range of 0 to 50%.

6. The fiber random distribution RVE generation method based on lattice partitioning according to claim 1, characterized in that: Taking the center of the RVE window as the coordinate origin and the lower left vertex of the RVE window as the center of the first lattice, all lattice centers contained in the RVE window are calculated, and the RVE window is divided into lattices according to the lattice center coordinates.

7. The fiber random distribution RVE generation method based on lattice partitioning according to claim 1, characterized in that: Step (4) includes the following sub-steps: Step (4.1): Compare the distances between the fiber center and the centers of all the lattices to be matched, take the lattice with the closest distance as its closest lattice, and move the lattice out of the list of lattices to be matched. The moving direction of the fiber is set to the direction starting from the fiber center and ending at the center of the closest lattice; Step (4.2): Calculate the maximum movable distance of the fiber when it moves along the moving direction Step (4.3): Determine the maximum movable distance Is it greater than or equal to the movable distance threshold l? thre If so, the fiber movement distance is If not, the fiber moving direction is randomly specified and the process goes to step (4.2); wherein the fiber movable distance threshold l thre It is equal to the difference between the adjacent lattice centers and the fiber diameter.

8. The fiber random distribution RVE generation method based on lattice partitioning according to claim 1, characterized in that: Step (5) includes the following sub-steps: Step (5.1): Randomly generate new fibers F try =(x try ,y try ), x try =rand[-L / 2,L / 2],y try =rand[-W / 2,W / 2]; Step (5.2): Compare whether the fiber overlaps with the existing fiber. If so, go to step (5.1) until the maximum number of attempts is reached. When the number of attempts reaches the maximum number of attempts, go to step (4). If not, accept the fiber and determine whether the required number of fibers is reached. If so, the fiber generation is completed. If not, go to step (5.1).

9. A fiber random distribution RVE generation system based on lattice partitioning, characterized by: The system includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the method for generating a fiber random distribution RVE based on lattice partitioning according to any one of claims 1 to 8 is executed.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores machine-executable instructions. When the machine-executable instructions are called and executed by the processor, the machine-executable instructions prompt the processor to implement the lattice partitioning-based fiber random distribution RVE generation method described in any one of claims 1-8.

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