CN107679341B

CN107679341B - Finite element parametric modeling method for barrel structure

Info

Publication number: CN107679341B
Application number: CN201711034851.8A
Authority: CN
Inventors: 邹利波; 于存贵; 孙同生; 赵纯; 秦予峥
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2017-10-30
Filing date: 2017-10-30
Publication date: 2021-03-02
Anticipated expiration: 2037-10-30
Also published as: CN107679341A

Abstract

The invention provides a finite element parametric modeling method for a barrel structure, which comprises the following steps: establishing a three-dimensional geometric model of the straight cylindrical barrel through finite element software; dividing a finite element mesh into the geometric model; an execution log file automatically generated by finite element CAE software is changed into a Python script program file rpy to form a Python script language, and the parameters of the barrel structure are replaced by variables to realize parametric modeling; exporting an Inp file of a finite element model of the straight cylindrical barrel; reading the node coordinates of each layer of unit along the barrel axis contained in the Inp file by using a Python language to form a barrel finite element mesh model; and updating Inp, and importing the Inp into commercial finite element CAE software, namely generating a barrel finite element mesh model.

Description

Finite element parametric modeling method for barrel structure

Technical Field

The invention relates to a computer simulation technology, in particular to a barrel structure finite element parametric modeling method.

Background

The barrel is the basic component that provides the ballistic process within the gun, withstanding extremely high powder gas pressures. During the process of launching the projectile, a large amount of high-temperature and high-pressure gas is generated instantly when gunpowder burns to push the projectile to move along the axis direction of the barrel, in the process, the projectile and the rifling of the barrel are mutually extruded, and the belt material undergoes high transient large deformation, friction and other processes. The movement of the projectile in the bore is a highly non-linear problem. The research on the initial motion process in the projectile chamber has important significance for researching the motion rule of the projectile. With the development of science and technology, finite element methods gradually become mainstream methods for studying such problems. In the finite element model, the structure and the grid precision of the barrel finite element grid are particularly important for the accuracy of the simulation calculation result.

The inner bore structure of the rifling barrel is complex and is loaded badly. When using finite element analysis, the barrel rifling geometry is discretized. The general barrel is provided with a plurality of rifling lines, the geometrical size of the cross section of each rifling line is smaller than the caliber of the barrel, and the rifling lines rotate spirally around the axis of the barrel to influence the establishment of a finite element mesh of the barrel and the division of excellent units.

In the technical field of finite element analysis, the whole analysis time occupied by pretreatment modeling is more than 60%, and the conventional modeling technical means is to establish a simplified barrel geometric model in three-dimensional modeling software according to a design drawing, then introduce the simplified barrel geometric model into the pretreatment software for grid division, and finally introduce the divided grid model into finite element software for simulation calculation. The mutual introduction of data among various software not only causes complex operation, but also easily causes data loss, and takes longer time, and the precision of the grid model is poorer. Furthermore, when the pre-processing is performed for barrel mesh division, the quality of the divided mesh is not very good due to the complexity of the barrel structure.

Disclosure of Invention

The invention provides a finite element parametric modeling method for a barrel structure, which can realize rapid and accurate parametric modeling of a barrel medicine chamber, a slope chamber structure, a guide part and the outer contour of the barrel through secondary development.

The technical scheme for realizing the purpose of the invention is as follows: a finite element parametric modeling method for a barrel structure comprises the following steps:

step 1, establishing a three-dimensional geometric model of a straight cylindrical barrel through finite element software;

step 2, dividing a finite element mesh into the geometric model;

step 3, automatically generating an execution log file by finite element CAE software, changing a filename suffix of rpy into a Python script program file of py, forming a Python script language, and replacing the structure parameters of the body pipe by using variables to realize parametric modeling;

step 4, exporting an Inp file of the finite element model of the straight cylindrical barrel;

step 5, reading the node coordinates of each layer of unit along the barrel axis contained in the Inp file by using Python language to form a barrel finite element mesh model;

and 6, updating Inp, and importing the Inp into commercial finite element CAE software, namely generating a barrel finite element mesh model.

By adopting the method, the specific process of the step 5 is as follows:

step 5.1, positioning to a rifling initial part unit by using the same z-direction coordinates of front and rear end surface nodes of each layer of unit of the barrel, taking an end surface node close to the gun tail direction as a source surface node, and taking the other end surface node as a terminal surface node;

step 5.2, taking the source surface node as a fixed point, taking the terminal surface node as an offset node, and taking the source surface node to the terminal surface node as the barrel axial direction;

step 5.3, carrying out any angle rotation deviation on one node (x, y) according to the barrel winding degree and the rifling form to obtain a new coordinate (x ', y')

And 5.4, the node offset of the next layer of unit is performed on the basis of the unit of the previous layer, and the operations are repeated, so that the node offset of the whole body pipe can be completed, and a body pipe finite element mesh model is formed.

The method can quickly, effectively and accurately establish the finite element mesh model of the barrel structure, and can carry out parametric modeling on the barrel structure so as to establish the finite element mesh model of the barrel with any different calibers.

The invention is further described below with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic flow diagram of the process of the present invention.

Figure 2 is a schematic view of a barrel rifling configuration.

FIG. 3 is a schematic diagram of a straight cylindrical barrel mesh finite element model.

FIG. 4 is a schematic diagram of cell layer identification.

Fig. 5 is a schematic diagram of the cell node offset principle.

Fig. 6 is a schematic diagram of node offset calculation.

FIG. 7 is a schematic diagram of a finite element mesh model of a 76mm barrel.

Detailed Description

With reference to fig. 1 to 6, a method for parametrizing and modeling a barrel structure includes the following steps:

step 1, according to the actual size of the barrel bore structure, in ABAQUS software, according to the method of a central small circle (the diameter of the central small circle is the width of a female line) as shown in figure 2, establishing the rifling section of the gun barrel. And the section of the barrel is stretched to form the straight cylindrical barrel.

And 2, dividing a finite element mesh for the straight cylindrical artillery barrel, as shown in figure 3.

And 3, in the process of generating the straight cylindrical barrel grid, automatically generating an execution log file (. rpy) by ABAQUS software, finding a corresponding statement in the file by almost each step of CAE operation, changing the suffix of the file name into a Python script program file (.py) to form a Python script language, and replacing the barrel structure parameter by a variable to facilitate parametric modeling.

Step 4, generating an Inp file containing units and nodes;

and 5, reading the node coordinates of each layer of unit along the axis of the barrel contained in the Inp file by using a Python language to form a barrel finite element mesh model.

For example: as shown in fig. 4, the same z-direction coordinates of the front and rear end face nodes of each layer unit of the barrel are used to position the barrel to the rifling start unit (assuming that the 3 rd layer unit is the rifling start unit), the end face node near the tail direction is used as the source face node, and the other end face node is used as the end face node. After the source node and the terminal node of the unit are identified, the source node is used as a fixed point, and the terminal node is used as an offset node. As shown in fig. 5, for example, in this unit,

nodes

100, 101, 102, 103 are source nodes,

nodes

200, 201, 202, 203 are terminal nodes, and the source to terminal nodes are barrel axial directions. When the node is shifted, taking the node 203 as an example, the node 203 is one of the terminal surface nodes of the unit and is also one of the source surface nodes of another unit, the node is shifted according to the barrel winding degree and the rifling form, and after rotating by any angle according to a point 203(x, y) on the same circle, the new coordinates 203(x ', y') after the shift can be obtained by the formula (1), that is, the node shift of the layer unit is completed, as shown in fig. 6. Node deviation of the next layer of units is carried out on the basis of the units of the previous layer, and the operations are repeated, so that node deviation of the whole body pipe can be completed, and a body pipe finite element mesh model is formed. The method has the advantages that the barrel finite element mesh model is modeled on the basis of the finite element unit nodes, the accuracy of the established model is high, time period is consumed for modeling, geometric distortion and data loss of the model cannot be generated compared with the traditional modeling method, and the barrel finite element mesh model with higher accuracy can be provided for correlation related to barrel finite element calculation.

And 6, importing the modified node coordinates into a new Inp file to form a barrel finite element mesh model.

FIG. 7 shows a 76mm barrel finite element mesh model generated using this method.

Claims

1. A finite element parametric modeling method for a barrel structure is characterized by comprising the following steps:

step 2, dividing a finite element mesh into the geometric model;

step 6, updating the Inp file, and importing the Inp file into commercial finite element CAE software, namely generating a barrel finite element mesh model;

the specific process of the step 5 is as follows:

x ′ = x c o s ( θ ) - y s i n ( θ ) y ′ = x s i n ( θ ) + y c o s ( θ ) ;

θ is the angle of rotation of (x, y);

and 5.4, repeating the steps 5.1 to 5.3 on the basis of the node offset of the unit of the next layer and the unit of the previous layer, so that the node offset of the whole body pipe can be completed, and a body pipe finite element mesh model is formed.