CN103268385B - A kind of generation method of finite element skeleton unit - Google Patents

Abstract

The invention provides a method for generating a finite element skeleton unit. It can be used in the pre-processing software for finite element analysis to quickly and effectively generate continuous skeleton elements. The continuity of the matrix material in the present invention is defined as: among all matrix material units, any unit has two common nodes with one or two adjacent units, and these two common nodes are adjacent rather than opposite. The continuity of the skeleton element is defined as: In a continuous matrix material distribution, the next node of the skeleton element generated by the previous matrix element must be the same as the starting node of the skeleton element generated by the current matrix element in number and geometric position , that is, the nodes have continuity in the distribution. The nodes of the skeletal elements generated by this method must meet the requirements of continuous skeletal material distribution, and can be imported into the finite element analysis. Under the condition of meeting the specific requirements of users, the work efficiency and work enthusiasm are greatly improved.

Description

A Method for Generating Finite Element Skeleton Elements

technical field

The invention relates to an automatic generation method for finite element skeleton units, which can be used in pre-processing software for finite element analysis, and can quickly and effectively generate continuous skeleton units.

Background technique

Since some materials are limited by their own physical properties and cannot meet the strength requirements of certain specific projects, it is often necessary to add a certain amount of reinforcing materials to meet their strength requirements. In finite element analysis, the material to be reinforced is usually called matrix material, and the reinforced material is called skeleton material. When performing finite element analysis, it is necessary to embed the corresponding skeleton unit in the matrix material unit during preprocessing. In order to ensure the consistency of the strength and stiffness of the skeleton material during the analysis process, it is necessary to make the distribution of the skeleton unit meet the requirements for continuity. . As far as the current commercialized finite element software is concerned, the process of generating skeleton material elements is relatively cumbersome, so it is necessary to carry out secondary development on the preprocessing of skeleton material elements to meet the special needs of users.

In the tire industry, due to the high elasticity and low elastic modulus of rubber, it is easy to undergo large deformation under a certain external force, so a certain amount of steel cords, cords, etc. are added to many parts of it. The skeleton material is used to enhance the strength of the tire and the deformation ability against external force. Therefore, in the finite element analysis of the tire, it is necessary to generate a correspondingly large number of skeleton elements for the matrix material of these parts. At the same time, considering the needs of the skeleton material to bear the force, this requires that the skeleton material must be continuously distributed, and at the same time must satisfy a certain direction distribution. However, the skeleton materials automatically generated by general commercial software according to the generation rules of the skeleton materials are usually disorderly and in the wrong direction, which cannot meet the requirements for continuous distribution, resulting in a lot of boring and tedious workload. In order to automatically generate correct, orderly and continuous skeleton material units, reduce working time, and improve work efficiency, it is necessary to adopt a new method for automatic generation of skeleton materials, which is extracted from the pre-processing grid division information file in the form of computer programming. The number and geometry information of the relevant matrix material elements and their nodes can automatically generate the correct skeleton elements.

Contents of the invention

The invention provides a simple and feasible method for automatically generating skeleton units by using the computer programming language Python, and at the same time can ensure that the skeleton units generated by the method have complete continuity.

The continuity of the matrix material is defined as: among all matrix material units, any unit has two common nodes with its adjacent one (unit at the end point) or two units, and these two common nodes are adjacent and Not relative. The continuity of the skeleton element is defined as: In a continuous matrix material distribution, the next node of the skeleton element generated by the previous matrix element must be the same as the starting node of the skeleton element generated by the current matrix element in number and geometric position , that is, the nodes have continuity in the distribution.

The principle of the skeleton unit generated by the present invention is: under the premise that the matrix unit corresponding to the skeleton unit to be generated is a continuous quadrilateral unit, according to the requirement of continuity, take the midpoint of the common side of two adjacent units and its opposite The midpoint of the edge generates two nodes of the skeleton element respectively, and then connects these two nodes to generate the skeleton element. Therefore, the requirement of skeleton unit continuity must be met during the generation process.

A method for generating a finite element skeleton unit, the steps of which are:

The first step is to read the unit number, node number and geometric information: by reading the finite element pre-processing unit mesh division information, the unit number of the matrix material to be added to the skeleton and the corresponding node number and geometric information are obtained; To avoid duplication of unit numbers during finite element analysis, the skeleton unit number must be greater than the maximum unit number of all units, and the starting unit number of the defined skeleton unit is m; in order to avoid duplication of node numbers in the analysis process, the skeleton node number must be is greater than the maximum node number of all nodes, define the starting number of the skeleton node as n; put all the obtained units and nodes into the unit set ES and the node set S1 respectively, and make a good connection between the unit and the node to which the unit belongs Correspondence.

The second step is to obtain the end node set: in order to ensure that the skeleton unit is continuous, the distribution of the corresponding matrix material unit must also have certain continuity; according to the definition of matrix unit continuity, in all units of this matrix material , except for the end unit, all nodes on other units will appear at least twice in the node set S1, that is, the end unit nodes are unique; according to the continuity judgment theory of the matrix unit, all nodes in the node set S1 The nodes that appear once are the nodes contained in the end unit of this matrix material, and the nodes that only appear once are put into the end node set S2.

The third step is to select the starting node and the starting unit: select a node from S2 as the starting node P0, since this node only appears in one end unit, the starting unit E1 can be inversely deduced; by The node sequence corresponding to unit E1 is compared with the end node set S2, and the node P0 that has appeared is excluded, and another end node P1 can be obtained; in order to avoid continuing the used nodes and units in subsequent operations, the P0 and P1 are deleted from the end set S2, and E1 is deleted from the unit set ES; at this time, the two nodes needed to generate the skeleton unit m are obtained, and the skeleton unit m is obtained according to the generation rules of the skeleton material unit The first node, numbered n, is located at the midpoint of the line connecting P0 and P1.

The fourth step is to generate a skeleton unit: the other point of this skeleton unit m+j is the midpoint of the line connecting the remaining two points P2 and P3 of the quadrilateral base unit E1, and the node number is n+j+1, Where j represents the number of cycles; at this time, the skeleton unit is successfully generated, and its corresponding unit number and node number are m+j and (n+j,n+j+1); nodes P2 and P3 are used as new The starting nodes P0 and P1.

The fifth step is to determine the position of the new starting node: determine whether the new starting nodes P0 and P1 are located in the end set S2; if the new starting node is located in the end set, delete P0 and P1 from S2 , at this time, if S2 is an empty set, it means that all base units have successfully generated skeleton units, and if it is not an empty set, execute the third step; if the new node is not in the end node set S2, compare the node with The corresponding relationship between units, get the corresponding unit number, and under the premise of ensuring that this unit is in the unit set ES, get the new starting unit E1, and then perform the fourth step; the newly generated node and unit number The j represents the number of times the loop is performed.

In the sixth step, when the end node set S2 is an empty set, it indicates that the skeleton units corresponding to all matrix material units have been successfully generated, and the numbers of all skeleton units and their node numbers and geometric information can be obtained, and the corresponding The numbers of the skeleton elements and their nodes are m+j:(n+j,n+j+1) respectively. At the same time, the nodes of the skeletal elements generated by this method must meet the requirements of continuous skeletal material distribution, which can be imported into the finite element analysis, and the work efficiency and enthusiasm for work can be greatly improved while meeting the specific requirements of users.

Description of drawings

Fig. 1 is a tire carcass material unit;

Fig. 2 is a tire carcass skeleton material unit.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings: the present embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation is provided, but the protection scope of the present invention is not limited to the following embodiments.

According to the implementation steps of the present invention, firstly, the unit numbers and node numbers of the carcass material located under the traveler are extracted from the finite element pre-processing unit division information. As shown in Figure 1, the numbers with lighter colors are unit numbers, and the numbers with darker colors are node numbers. All the carcass base units are quadrilateral units, and there are 7 units in total. All the units are distributed from left to right, and the node numbers are in counterclockwise order to obtain the correspondence between the units and nodes as shown in the following table relation.

The resulting element set SE is: (60,37,36,35,34,53,52), and the node set S1 is: (71,50,49,48,48,49,29,47,47,29 ,28,46,46,28,27,45,45,27,43,44,44,43,42,65,65,42,41,64). In order to avoid repeated appearance of unit and node numbers in finite element analysis and affect the calculation, the starting unit number of the skeleton unit is set to m=1000, and the starting number of the skeleton node is set to n=1000.

Repeatedly check all nodes in S1, and add all nodes that appear more than 2 times (including 2 times) in S1 to the end set S2 to get S2: (71,50,64,41) .

A node is randomly selected from the end set as the initial node, and node 71 is selected as the initial node P0 in this embodiment. It can be seen from the correspondence between units and nodes that P0 is located in unit 60, so the starting unit E1 is 60. The node list contained in the starting unit E1 is: (71,50,49,48). Comparing this node list with the end set S2, it is found that except for P0, the number of recurring nodes is 50, so P1 is node 50. Delete nodes P0 and P1 from S2, at this time the end set S2 is: (64,41), delete E1 from the unit set SE, at this time the unit set SE: (37,36,35,34,53, 52). Through the nodes P0 and P1, the first node of the first skeleton unit can be obtained, the node number is 1000, and it is located at the midpoint of the line connecting P1 and P2.

In the node list of E1, except P0 and P1, the remaining two nodes are 49 and 48, which are the corresponding P3 and P4. According to the generation rules of skeleton nodes, the second node is 1001, which is located at the midpoint of the line connecting P3 and P4. At this point, the first skeleton unit is successfully generated, and the corresponding unit number and node number are: 1000:(1000,1001).

At this time, it is necessary to judge the positions of P3 and P4 to determine whether they are located in the end set S2. Through the comparison with S2, it is found that P3 and P4 do not belong to the set S2. At this time, P3 and P4 are used as new P0 and P1 respectively, and new skeleton units can be obtained by repeated operations.

The cycle continues, when the number of the base unit is 52, and the corresponding P3 and P4 node numbers are 64 and 41 respectively, compare it with S2, and find that both 64 and 41 are in the end set S2, so it is removed from S2 Deleted in . At this time, none of the elements in the S2 set is an empty set, indicating that the skeleton material units corresponding to all matrix units have been automatically generated at this time, and the final generated skeleton units and their corresponding nodes and matrix unit numbers are listed in the following table As shown in Fig. 2, the corresponding diagram of the generated skeleton unit and base unit is shown in Fig. 2, where the number with lighter color is the number of skeleton unit, and the number with darker color is the number of skeleton node.

The above are only preferred specific implementations of the present invention. These specific implementations are all based on different implementations under the overall concept of the present invention, and the scope of protection of the present invention is not limited thereto. Anyone familiar with the technical field Within the technical scope disclosed in the present invention, any changes or substitutions that can be easily conceived by a skilled person shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (1)

1. A generation method of finite element skeleton unit, is characterized in that, The first step is to read the unit number, node number and geometric information: by reading the finite element pre-processing unit mesh division information, the unit number of the matrix material to be added to the skeleton and the corresponding node number and geometric information are obtained; To avoid duplication of unit numbers during finite element analysis, the skeleton unit number must be greater than the maximum unit number of all units, and the starting unit number of the defined skeleton unit is m; in order to avoid duplication of node numbers in the analysis process, the skeleton node number must be is greater than the maximum node number of all nodes, define the starting number of the skeleton node as n; put all the obtained units and nodes into the unit set ES and the node set S1 respectively, and make a good connection between the unit and the node to which the unit belongs Correspondence; The second step is to obtain the end node set: in order to ensure that the skeleton unit is continuous, the distribution of the corresponding matrix material unit must also have certain continuity; according to the definition of matrix unit continuity, in all units of this matrix material , except for the end unit, all nodes on other units will appear at least twice in the node set S1, that is, the end unit nodes are unique; according to the continuity judgment theory of the matrix unit, all nodes in the node set S1 The nodes that appear only once are the nodes included in the end unit of this matrix material, and put the nodes that only appear once into the end node set S2; The third step is to select the starting node and the starting unit: select a node from S2 as the starting node P0, since this node only appears in one end unit, the starting unit E1 can be inversely deduced; by The node sequence corresponding to the unit E1 is compared with the end node set S2, and the node P0 that has already appeared is excluded, and another end node P1 can be obtained; in order to avoid continuing the used nodes and units in subsequent operations, P0 and P1 are deleted from the end set S2, and E1 is deleted from the element set ES; at this time, the two nodes needed to generate the skeleton unit m are obtained, and according to the generation rules of the skeleton material unit, the first node of the skeleton unit m is obtained A node number n is located at the midpoint of the line connecting P0 and P1; The fourth step is to generate a skeleton unit: the other point of this skeleton unit m+j is the midpoint of the line connecting the remaining two points P2 and P3 of the base unit E1, and the node number is n+j+1, where j Indicates the number of cycles; at this time, the skeleton unit is successfully generated, and its corresponding unit number and node number are m+j and (n+j,n+j+1); take nodes P2 and P3 as new starting points Start nodes P0 and P1; The fifth step is to determine the position of the new starting node: determine whether the new starting nodes P0 and P1 are located in the end set S2; if the new starting node is located in the end set, delete P0 and P1 from S2 , at this time, if S2 is an empty set, it means that all base units have successfully generated skeleton units, and if it is not an empty set, execute the third step; if the new node is not in the end node set S2, compare the node with The corresponding relationship between units, get the corresponding unit number, and under the premise of ensuring that this unit is in the unit set ES, get the new starting unit E1, and then perform the fourth step; the newly generated node and unit number The j represents the number of cycles; In the sixth step, when the end node set S2 is an empty set, it indicates that the skeleton units corresponding to all matrix material units have been successfully generated, and the numbers of all skeleton units and their node numbers and geometric information can be obtained, and the corresponding The numbers of the skeleton elements and their nodes are m+j: (n+j,n+j+1).