CN-121983197-A - Random distribution generation method of high-volume-fraction fibers based on grid

CN121983197ACN 121983197 ACN121983197 ACN 121983197ACN-121983197-A

Abstract

The invention discloses a grid-based high-volume-fraction fiber random distribution generation method, and relates to the field of numerical simulation of fiber reinforced composite materials. The method comprises the steps of firstly setting parameters such as a fiber radius, a target volume fraction and the like, constructing a first grid system for fiber throwing and conflict detection and a second grid system for density evaluation, randomly selecting a unit throwing fiber in the first grid system, calculating a rejection area, updating a unit state, calculating the proportion of unoccupied areas in a fiber reference range based on the second grid system to determine fiber retention if the target volume fraction is not reached, and iterating to reach standards or reach an iteration upper limit by updating the grid state and reducing the reference value. The method can rapidly generate random fiber distribution with the volume fraction of more than 0.77, meets periodic boundary conditions, and is suitable for constructing a two-dimensional initial geometric model of a representative volume unit of the composite material.

Inventors

ZHANG PENG
HOU CHAOHUI
CHEN JUNQI
CUI WEIHUA

Assignees

河南工业大学

Dates

Publication Date: 20260505
Application Date: 20260121

Claims (10)

1. A method for generating random distribution of high volume fraction fibers based on a grid, which is characterized by comprising the following steps: S100, respectively constructing a first grid system for fiber position throwing and conflict detection and a second grid system for fiber distribution density evaluation based on preset parameters and throwing area sizes; S200, randomly selecting available throwing units in the first grid system, determining the center position of a fiber in the selected units to throw the fiber, calculating the rejection area of the thrown fiber according to the position and the radius of the thrown fiber, and updating the state of the units influenced by the rejection area in the first grid system, and marking the states as unavailable; S300, stopping fiber feeding and calculating total volume fraction of currently fed fibers when no available feeding units exist in the first grid system, judging whether the current volume fraction reaches a preset target volume fraction, if so, outputting a current fiber distribution result, otherwise, executing step S400; S400, traversing all the thrown fibers based on the second grid system, calculating the proportion of unoccupied areas in a preset reference range of each fiber, comparing the proportion of unoccupied areas with a dynamically adjusted reference value, and determining whether to retain the fiber according to a comparison result; S500, clearing the occupation state of the second grid system, updating the available state of the first grid system, reducing the reference value, and repeatedly executing the steps S200 to S500 until the current volume fraction reaches the target volume fraction or the preset upper limit of the iteration times.
2. The method for generating a random distribution of high volume fraction fiber based on grid of claim 1, wherein in step S100, the process of constructing the first grid system comprises: s110, discretizing the throwing area into m multiplied by m large throwing lattices; S120, further discretizing each large throwing lattice into n multiplied by n small throwing lattices; S130, establishing a jettisonable state for each small jettisoning lattice and initializing the states as jettisonable; S140, maintaining a small-grid quantity counter capable of being thrown for each large throwing grid and initializing the small-grid quantity counter to n2.
3. The grid-based high volume fraction fiber random distribution generation method according to claim 1, wherein in the step S200, the randomly selected available delivery units are specifically: s210, randomly selecting a large throwing lattice with the number of throwing small lattices being more than 0; S220, if the number of the small throwing lattices of the large throwing lattice is equal to n2, randomly selecting one of all n multiplied by n small throwing lattices in the large throwing lattice; S230, if the number of the small throwing lattices of the large throwing lattice is smaller than n2, randomly selecting one of the small throwing lattices with the throwing states in the large throwing lattice; s240, randomly determining a point in the selected small throwing lattice as a fiber circle center.
4. The method for generating a random distribution of high volume fraction fibers based on a grid according to claim 1, wherein the specific process of updating the cell status affected by the exclusion zone in the first grid system in step S200 comprises: s250, traversing each large throwing lattice intersected with the square circumscribed by the exclusion area; s260, if the large throwing lattices are completely located in the rejection area, the number of the small throwing lattices of the large throwing lattices is directly updated to 0; s270, if the large throwing lattices intersect with the repulsive area boundary, traversing each small throwing lattice in the large throwing lattices further, and judging whether the small throwing lattices intersect with the repulsive area; and S280, if the small throwing lattices are intersected and the states of the small throwing lattices are throwable, updating the states of the small throwing lattices into non-throwable states, and subtracting 1 from the number of the throwable small lattices of the large throwing lattices to which the small throwing lattices belong.
5. The method for generating a random distribution of high volume fraction fiber based on grid of claim 1, wherein in step S100, the process of constructing the second grid system comprises: S150, discretizing the put-in area into S multiplied by S large-occupied lattices; s160, further discretizing each large-occupied grid into t multiplied by t small-occupied grids; s170, establishing an occupied state for each small occupied cell and initializing to be unoccupied; S180, an unoccupied small lattice number counter is maintained for each large occupied lattice and initialized to t2.
6. The method for generating random distribution of high volume fraction fiber based on grid of claim 1, wherein in step S400, the process of calculating the proportion of unoccupied areas within the preset reference range specifically comprises: S410, calculating a circular reference area which takes the center of each put-in fiber as a center and has a radius which is k times of the radius of the fiber; S420, traversing each large-occupied cell intersected with the square circumscribed by the circular reference area, and counting the number of unoccupied small cells of the large-occupied cells completely located in the reference area and the number of unoccupied small-occupied cells intersected with the reference area in the large-occupied cells intersected with the boundary of the reference area; S430, counting the total number of the unoccupied small lattices obtained through statistics as a numerator, and counting the total number of the small occupied lattices in the reference area as a denominator, wherein the ratio of the total number of the small occupied lattices in the reference area to the unoccupied area is the ratio of the unoccupied areas.
7. The grid-based high volume fraction fiber random distribution generation method according to claim 1, wherein in the step S400, an initial value of the dynamically adjusted reference value is set by a user and is reduced according to a predetermined strategy in the step S500 of each iteration.
8. The grid-based high volume fraction fiber random distribution generation method of claim 1, wherein said step S200 further comprises: And S290, when the thrown fiber intersects with the boundary of the throwing area, generating one or more supplementary circles, wherein the circle center of each supplementary circle is obtained by translating the circle center coordinates of the fibril by one or more throwing area widths, so as to ensure the periodic boundary condition of fiber distribution.
9. The method for generating a random distribution of high volume fraction fibers based on a grid as set forth in claim 1, wherein in the step S400, the step of determining whether to retain the fibers according to the comparison result is specifically to retain the fibers and all complementary circles corresponding thereto if the unoccupied area ratio is smaller than the current reference value, and otherwise, mark the fibers and the complementary circles thereof as to be deleted.
10. The grid-based high volume fraction fiber random distribution generation method of claim 1, wherein the method is adapted to generate a two-dimensional initial geometric model of a representative volume element of the fiber reinforced composite material, the generated fiber volume fraction being above 0.77.

Description

Random distribution generation method of high-volume-fraction fibers based on grid Technical Field The invention relates to the technical field of numerical simulation of fiber reinforced composite materials, in particular to a grid-based random distribution generation method of high-volume-fraction fibers. Background The fiber reinforced composite material has wide application prospect in the fields of aviation, aerospace, automobiles, buildings and the like, has mechanical problems in the processes of designing, processing, forming, applying and the like of the fiber reinforced composite material, and researchers often adopt a finite element method to study the material performance of the fiber reinforced composite material, and generally adopt a representative volume unit (REPRESENTATIVE VOLUME ELEMENT, RVE) model to calculate and analyze the equivalent mechanical property of the material. In order to create a suitable representative volume unit, it is necessary to consider the distribution of the fibers in the matrix in addition to the volume fraction of the fibers, the size of the fibers, the physical properties of the individual components. Most of the existing methods assume that the distribution of the fibers is regular to simplify the microstructure analysis of the representative volume units, whereas the true distribution of the fibers in the matrix is random. Thus, the established representative volume units should exhibit such randomness and non-uniformity as accurately as possible. Currently, there is a lack of an effective method for producing high volume fraction fibers at a relatively high rate. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art. Disclosure of Invention The invention aims to overcome the defects and provide a grid-based random distribution generation method for high-volume-fraction fibers. In order to solve the technical problems, the technical scheme provided by the invention is as follows: A method for generating random distribution of high-volume-fraction fibers based on grids comprises the following steps of S100, respectively constructing a first grid system for fiber position throwing and conflict detection and a second grid system for fiber distribution density evaluation based on preset parameters and throwing area sizes, S200, randomly selecting available throwing units in the first grid system, determining fiber center positions in selected units to carry out fiber throwing, calculating a repulsive area according to the positions and radiuses of the thrown fibers, updating unit states influenced by the repulsive area in the first grid system, marking as unavailable, S300, stopping fiber throwing when no throwing units are available in the first grid system, calculating total volume fraction of currently thrown fibers, judging whether the current volume fraction reaches a preset target volume fraction, if so, outputting a current fiber distribution result, otherwise, executing step S400, traversing all the fibers based on the second grid system, calculating unoccupied area proportion in a preset reference range for each fiber, calculating unoccupied area proportion in the preset reference range, and updating the unit states influenced by the repulsive area, marking as unavailable, stopping fiber throwing, calculating the total volume fraction of currently thrown fibers, judging whether the current volume fraction reaches the preset target volume fraction, repeatedly executing the current volume fraction or repeatedly executing the current grid until the current volume fraction reaches the preset target volume fraction, and comparing the current volume fraction to the first grid 500 or the current volume fraction until the current volume fraction reaches the preset target volume fraction, and the current volume fraction is reached to the current threshold value 500. Optionally, in the step S100, the process of constructing the first grid system includes the steps of S110, discretizing the drop area into m×m large drop lattices, S120, further discretizing each large drop lattice into n×n small drop lattices, S130, establishing a drop state for each small drop lattice and initializing the drop state to be drop, S140, maintaining a drop small lattice number counter for each large drop lattice and initializing the drop small lattice number counter to be n2. Optionally, in the step S200, the randomly-selected available throwing units specifically include S210 of randomly selecting a large throwing lattice with the number of the available throwing lattices being greater than 0, S220 of randomly selecting one of all n×n small throwing lattices in the large throwing lattice if the number of the available throwing lattices in