Preposed discrete rod full model initial speed calculation method

Abstract

The invention discloses a front discrete rod full model initial speed calculation method. The method comprises the following steps: establishing a three-dimensional geometric model containing air, transient high-pressure gas and discrete rods; defining material attributes of each part, adopting an ideal gas state equation for high-pressure gas, and adopting a rigid body material model for a discrete rod; the method comprises the following steps: performing hexahedral mesh generation on a single discrete rod, generating densely arranged discrete rod arrays in batches through a program integrating lct, lrep, gmi progressive increase and while circulation, adopting SALE structured meshes for high-pressure gas and air, and finally calculating and obtaining the initial velocity of flying through a finite element solver. According to the method, rapid parameterization construction of the ten-thousand-magnitude discrete rod model is achieved, the modeling efficiency is improved by 80% or above, the calculation efficiency is improved by 90% or above while the precision of the whole model is guaranteed, and the method is suitable for initial speed accurate forecasting of various special-shaped gas cavities and discrete rod configurations and can be extensively applied to various transient gas driving systems.

Description

Technical Field

[0001] This invention relates to the fields of computational mechanics and fluid mechanics, specifically to a method for calculating the initial velocity of a full model of a pre-discrete rod. Background Technology

[0002] Transient high-pressure gas-driven discrete rod systems have wide applications in defense and industrial fields such as impact testing, dynamic material performance testing, and warhead damage element design. In these systems, the initial velocity, spatial distribution, and synchronicity of the discrete rod group under high-pressure gas are key physical quantities that determine its terminal effect. Therefore, high-precision and high-efficiency prediction of its motion process is of paramount importance for optimizing system design, improving driving efficiency, and ensuring controllable behavior.

[0003] Currently, numerical simulation analysis of this physical process mainly relies on the finite element method, but existing technical solutions have significant shortcomings in terms of modeling strategies and computational efficiency, primarily in the following aspects:

[0004] Oversimplification of models makes it difficult to reflect real physical details: To avoid the huge computational cost of modeling large-scale discrete rods, traditional methods often oversimplify discrete rod groups. For example, a homogeneous continuum model is used instead of a real discrete rod array, or only local regions are modeled. Such methods cannot accurately reflect the interactions between discrete rods, complex spatial arrangements, and the independent trajectories of individual rods, resulting in significant biases in the prediction of key parameters such as initial scattering velocity, distribution pattern, and density.

[0005] Traditional Arbitrary Lagrange-Euler (ALE) methods have limitations when dealing with large-scale fluid-structure interaction problems. While these methods offer advantages in handling large fluid deformations, they face significant challenges when applied to coupling problems involving thousands of discrete rods with high-pressure gas. Firstly, with a large number of rods, the computational efficiency of traditional contact algorithms drops sharply and is prone to computational interruptions due to mesh distortion. Secondly, conventional fluid-structure interaction setups cannot completely prevent the "numerical leakage" of momentum at the interface, leading to inaccurate calculations of gas pressure acting on the rods and directly affecting the accuracy of initial velocity calculations.

[0006] Inefficient modeling and lack of parametric and automated capabilities: In existing technologies, building a full model containing thousands to tens of thousands of discrete rods typically relies on manual or semi-automatic geometric modeling and mesh generation, a cumbersome, time-consuming, and error-prone process. The lack of efficient, parametric batch generation methods makes iterative and optimized design of solutions for different rod shapes, sizes, and arrangements extremely difficult, severely restricting R&D efficiency.

[0007] In summary, the core contradiction of existing technologies lies in the difficulty of balancing computational accuracy and efficiency: simplifying the model sacrifices physical realism, while attempting to build a full model faces bottlenecks such as high computational costs and cumbersome modeling processes.

[0008] Therefore, there is an urgent need in this field for a technical solution that can efficiently and automatically build a full model and solve it using a high-fidelity numerical method, so as to achieve rapid and accurate prediction of the motion process of a transient high-pressure gas-driven discrete rod system. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a method for calculating the initial velocity of a pre-discrete rod full model, which can efficiently and accurately simulate the scattering process and initial velocity distribution of a large number of discrete rods driven by transient high-pressure gas. The core of this method lies in realistically recreating complex physical scenarios through full model modeling and advanced fluid-structure coupling algorithms.

[0010] The technical solution adopted in this invention is as follows:

[0011] A method for calculating the initial velocity of a full model of a pre-discrete rod, the specific steps of which are as follows:

[0012] S1. Based on the actual physical model, establish a three-dimensional geometric model that includes the air domain, the transient high-pressure gas domain, and the discrete rod array;

[0013] S2. Define the material properties for each component in the geometric model, where the high-pressure gas domain adopts the ideal gas law and the discrete rod array adopts a rigid body material model.

[0014] S3. Perform finite element hexahedral mesh generation on a single discrete rod, and generate a densely arranged array of discrete rods in a specified space using a parametric batch generation program; model the high-pressure gas domain and the air domain using arbitrary Lagrange-Euler structured meshes;

[0015] S4. An explicit dynamic finite element solver is used to perform fluid-structure interaction calculations to simulate the process of high-pressure gas driving the discrete rod to scatter, and the initial velocity of the discrete rod to scatter is obtained through post-processing.

[0016] Furthermore, in step S1, the shape, size, and location of the high-pressure gas domain are designed according to the actual application scenario. Its shape includes spheres, cylinders, and irregular shapes, and its geometric parameters can be parametrically changed according to actual needs.

[0017] Furthermore, in step S1, in order to accurately fill the complex irregular gas cavity, a volume fraction-based geometric filling method can be adopted to initially fill the high-pressure gas domain within the air domain, thereby efficiently handling the volume definition problem of irregular shapes.

[0018] Furthermore, in step S2, for the driving medium—transient high-pressure gas—it is preferable to use the ideal gas law for description. For the discrete rod, to balance computational efficiency and stability, its material properties can be defined using a rigid body constitutive model, and key parameters such as its elastic modulus, Poisson's ratio, and density can be set.

[0019] Furthermore, step S3 is the core of achieving efficient modeling, specifically as follows:

[0020] (1) Discrete Rod Meshing and Array Generation: First, the geometric model of a single discrete rod is meshed with high-quality hexahedral elements. Then, to solve the problem of low efficiency in manual arrangement, this invention automatically generates a densely arranged array of discrete rods in space through a parametric batch generation program. This program has high flexibility and can be implemented through strategies such as array replication and automatic incrementing of material numbers. The key dimensions such as the cross-sectional shape (e.g., square, circular) and length of the discrete rods can be parametrically changed according to actual needs.

[0021] (2) Fluid domain mesh generation: For the fluid domain containing high-pressure gas and air, an arbitrary Lagrange-Eulerian structured mesh is used for modeling. This is a meshing technique suitable for large deformation fluid analysis, which eliminates the need for traditional finite element volume meshing of the fluid domain and effectively avoids mesh distortion problems.

[0022] (3) Fluid-structure interaction setup: To accurately simulate the interaction force between the high-pressure gas and the discrete rods, this invention can employ a dedicated fluid-structure interaction algorithm, such as the arbitrary Lagrange-Euler structured fluid-structure interaction algorithm, to define the contact interface between the two. This algorithm can achieve leak-free transfer of momentum and energy between the fluid and the structure, ensuring that the gas pressure can be accurately applied to each discrete rod.

[0023] Furthermore, in step S4, after the solution is completed, the calculation results can be visualized and analyzed using post-processing software, outputting the scattering cloud map, velocity-time curve, distribution density, and scattering initial velocity cloud map of the discrete rod group.

[0024] The beneficial effects of this invention are as follows:

[0025] (1) This invention can automatically generate discrete rod arrays, improving modeling speed by more than 80%, and can efficiently construct full models of tens of thousands of discrete rods. By combining rigid body materials and SALE mesh technology, the computational efficiency is improved by more than 90% while ensuring accuracy.

[0026] (2) This invention adopts full model modeling and combines The leak-free fluid-structure interaction algorithm accurately describes the interaction between gas and discrete rods, and can truly reflect the complex arrangement structure and instantaneous scattering state of discrete rods, with accurate and reliable calculation results.

[0027] (3) This invention supports parametric design of high-pressure gas chambers (including irregularly shaped chambers) and discrete rod shapes (such as square and circular), and can quickly adapt to the modeling needs of different sizes, shapes and materials, and has wide applicability.

[0028] (4) The technical framework established by this invention has universality, and its core method can be easily extended to the simulation analysis of other types of transient gas-driven systems, with great application potential. Attached Figure Description

[0029] Figure 1 The image shows the scattering cloud diagram of the transient high-pressure gas-driven front discrete rod model in Example 1.

[0030] Figure 2 This is a schematic diagram of the finite element model of Example 1.

[0031] Figure 3 This is a diagram showing the arrangement of the discrete rods.

[0032] Figure 4 This is the initial velocity contour map of the discrete rod. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto.

[0034] Example 1

[0035] This embodiment takes a system with a diameter of 80mm as an example, where each discrete rod is a cylinder with a diameter of 1.5mm and a length of 10mm, and the total number of discrete rods is 2220. The specific modeling process is as follows:

[0036] S1. Establishment of 3D Geometric Model

[0037] First, based on the set system diameter (80mm), a sufficiently large air domain is established in the finite element preprocessing software to accommodate the entire dispersion process. Then, within this air domain, a high-pressure gas chamber with an initial volume and specific location is created according to the driving requirements. The high-pressure gas chamber is designed as a cylinder, and its shape, size, and location can be parametrically adjusted according to the actual application. A volume fraction-based geometry filling method is used (e.g., through...). (Keywords) Precisely fill the defined cavity area with high-pressure gas. For example... Figure 2 As shown, the finite element model in this embodiment includes a three-dimensional geometric full model of the high-pressure gas and the discrete rod. The high-pressure gas is located in the air filling the space, and the discrete rod is located outside the high-pressure gas.

[0038] S2, Material Property Definition

[0039] Assign appropriate material properties to each component in the geometric model. For high-pressure gases, use the ideal gas law (such as that in LS-DYNA). The transient expansion behavior is described using the *MAT_RIGID (rigid body material) model. For discrete rods, to balance computational efficiency and stability, the *MAT_RIGID model is used for definition, and parameters such as density, elastic modulus, and Poisson's ratio are set, thereby significantly improving the computational speed.

[0040] S3. Mesh Generation and Model Generation

[0041] Discrete rod mesh generation and array construction: First, a high-quality hexahedral element mesh is generated for each individual discrete rod (in this embodiment, a cylinder with a diameter of 1.5 mm and a length of 10 mm) (the arrangement and distribution diagram of the discrete rods is shown in the figure). Figure 3 (As shown). Then, a dense array of 2220 discrete bars is automatically generated in a specified space using a parameterized batch generation program (e.g., a program that uses LCT load curves, LREP array replication, and material number GMI increments, along with a while loop).

[0042] Fluid domain mesh setup: For regions containing air and high-pressure gases, use an arbitrary Lagrange-Eulerian structured mesh (e.g., through...). (Keywords) Generates multi-material SALE structured meshes, thus effectively handling large deformation problems without the need for traditional finite element volume meshing of the fluid domain.

[0043] Fluid-structure interaction setup: To accurately simulate the process of high-pressure gas driving a discrete rod, a fluid-structure interaction algorithm (e.g., through...) is used. The keyword defines an arbitrary Lagrange-Euler structured fluid-structure interaction (FSI) interface, which defines the interaction interface between the high-pressure gas and the discrete rod, ensuring the leakage-free transfer of momentum at the interface, thereby simulating the driving process with high fidelity.

[0044] S4. Solving and Post-processing

[0045] The model information generated in the above steps (such as the mesh.k file for discrete rods) is integrated with keywords such as material, mesh, and contact control into the calculation file. Then, an explicit dynamic finite element solver (such as the LS-DYNA solver) is called to perform the calculation. After the solution is completed, post-processing software is used to analyze the results, obtaining, for example... Figure 1 The scattered cloud map shown and Figure 4 The image shows the initial velocity cloud of the dispersion.

[0046] Through the detailed description of the specific embodiments above, and the step-by-step analysis in conjunction with the accompanying drawings, it is fully demonstrated that the technical solution of the present invention has sufficient feasibility, operability and significant technical effects.

Claims

1. A method for calculating a full model muzzle velocity of a front discrete rod, characterized by The method comprises the following steps: S1, establishing a three-dimensional geometric model comprising an air domain, a transient high-pressure gas domain and a discrete rod array; S2, defining material properties for each component in the geometric model, wherein the high-pressure gas domain adopts an ideal gas state equation and the discrete rod array adopts a rigid body material model; S3, performing hexahedral meshing on a single discrete rod and generating a densely arranged discrete rod array in a specified space through a parameterized batch generation program; modeling the high-pressure gas domain and the air domain using an arbitrary Lagrangian-Eulerian structured grid; S4, performing fluid-structure coupling calculation using an explicit dynamic finite element solver to simulate the process of high-pressure gas driving the scattering of discrete rods and output the initial velocity of the scattering of discrete rods.

2. The method of claim 1, wherein, In step S1, the shape of the high-pressure gas domain is a parameterizable geometric body, including a sphere, a cylinder or a special-shaped structure.

3. The method of claim 2, wherein, In step S1, the high-pressure gas domain is initially filled in the air domain using a method based on volume fraction geometry filling.

4. The method of claim 1, wherein, In step S3, the parameterized batch generation program generates the discrete rod array through array replication and automatic increment of material number.

5. The method of claim 4, wherein, The cross-sectional shape and length of the discrete rod can be parameterized, and the cross-sectional shape includes a square or a circle.

6. The method of claim 1, wherein, In step S3, a fluid-structure coupling algorithm is used to define the interaction interface between the high-pressure gas domain and the discrete rod array.

7. The method of claim 6, wherein, The fluid-structure coupling algorithm is an arbitrary Lagrangian-Eulerian structured fluid-structure coupling algorithm.

8. The method of claim 1, wherein, In step S4, the scattering cloud of the discrete rod group, the velocity-time curve and the initial velocity cloud of the scattering of the discrete rod group are obtained through post-processing.

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