A method for visualizing stress in the end cap of a solid rocket motor winding casing

Abstract

This invention discloses a method for visualizing the stress in the head of a solid rocket motor's wound shell, belonging to the field of solid rocket motor technology. The method comprises the following steps: constructing a finite element simulation model of the solid rocket motor's wound shell head structure, performing mechanical performance simulation analysis, obtaining stress state analysis results data, and performing post-processing; reading the post-processed stress state analysis results data, generating a single principal stress line based on principal stress trace theory, using a cylindrical coordinate system as the tracking basis, and controlling the tracking step size using the bisection method; adjusting the density of principal stress line generation based on spacing control parameters; adjusting the tracking line type of the principal stress line based on line type control parameters, and drawing a stress visualization image. This invention solves the problem that traditional fiber winding processes and thin-layer solid structures lack process guidance significance for stress visualization results.

Description

Technical Field

[0001] This invention belongs to the field of solid rocket engine technology, specifically relating to a method for visualizing the stress of the end cap of a solid rocket engine's wound shell. Background Technology

[0002] Solid rocket motor casings, as the main load-bearing structure of the engine, have a crucial impact on the overall performance and safety of the rocket. With the development of industrial technology, the design and manufacturing technology of solid rocket motor casings has continuously improved. Fiber-wound composite material casing heads, with their excellent material structural properties and pressure and corrosion resistance, have become the mainstream direction in casing design. In the design process of casing heads, simulation stress analysis is the most critical reference tool. Traditional stress analysis methods mainly rely on theoretical calculations and empirical formulas, but with the improvement of computing power, finite element analysis (FEA) allows designers to obtain detailed stress distribution information of the casing under various load conditions, thereby ensuring the safety and reliability of the design. The development of modern visualization technology makes the display of stress analysis results more intuitive. Through 3D modeling and graphics rendering technology, complex stress distributions can be visually displayed in the form of color, shape, etc. Various commercial finite element simulation software on the market (such as ANSYS, ABAQUS, etc.) provide model stress analysis and visualization functions. These tools integrate powerful calculation and graphics processing capabilities, allowing users to obtain detailed stress distribution maps through simple operations.

[0003] Existing commercial finite element simulation software for studying stress distribution in head structures primarily relies on finite element analysis contour plots for characterization. This makes it difficult to provide direct reference for the design of shell head structures, resulting in unclear optimization directions for winding design process parameters, high uncertainty in single optimizations, and long overall optimization time. Furthermore, existing open-source stress direction visualization programs (released by Wang Junpeng on GitHub) typically process data based on .stress format files. However, conventional commercial finite element simulation software, such as ABAQUS, cannot directly output .stress format files, requiring complex data processing, which is cumbersome and imposes a significant operational burden on users. Additionally, this stress direction visualization method is based on mesh node stress, using principal stress trajectories (PSLs) to characterize the maximum stress direction at each node within the object under external force. However, this method is not suitable for thin-layer solid structures, making it difficult to fully plot the principal stress trajectories of the entire model and clearly characterize the stress direction of the model.

[0004] Therefore, this invention proposes a method for visualizing the stress of a solid rocket motor winding shell head based on principal stress trajectories. It specifically addresses the impact of fiber winding process and thin-layer solid structure on stress visualization in the solid rocket motor winding shell head structure. At the same time, it optimizes the human-computer interaction method by controlling the stress line visualization display through parameter control, thereby reducing the burden on operators. Summary of the Invention

[0005] The technical problem to be solved:

[0006] To overcome the shortcomings of existing technologies, this invention provides a method for visualizing the stress of a solid rocket motor winding shell end cap. Through a unique stress data post-processing workflow, principal stress line generation and density control mechanism, and linear trajectory adjustment technology, it solves the problem that traditional fiber winding processes and thin-layer solid structures lack process guidance for stress visualization results.

[0007] The technical solution of this invention is: a method for visualizing the stress of the end cap of a solid rocket motor winding casing, the specific steps of which are as follows:

[0008] A finite element simulation model of the solid rocket motor winding shell head structure was constructed, mechanical performance simulation analysis was performed, stress state analysis results were obtained and post-processed.

[0009] After reading the stress state analysis results data after processing, based on the principal stress trace theory, using the cylindrical coordinate system as the tracking basis, and using the bisection method to control the tracking step size, a single principal stress line is generated.

[0010] The density of principal stress line generation is adjusted based on spacing control parameters;

[0011] By adjusting the tracking line type of the principal stress line based on the line type control parameters, a stress visualization image is drawn.

[0012] A further technical solution of the present invention is: the post-processing method for the stress state analysis result data is as follows:

[0013] The stress state analysis results are simplified by outputting the element integral point stress and node coordinate data of the shell split structure to be processed from the simulation results and storing them as a general format data storage file.

[0014] Read the stress magnitudes at the integration points in the reduced integration elements of the conical shell from the data storage file, set each row as an element according to the element index number, and store it as a stress matrix according to the natural output order of the software. At this time, the row index of the matrix is ​​the arrangement order number of the elements.

[0015] Read the cone-shell reduced integral element node index data and node coordinate data from the data storage file. Set each row as an element according to the x, y, z coordinates of the element nodes, and store them as a node matrix according to the natural output order of the software. At this time, the row number index of the matrix is ​​the node number index. Set each row as an element according to the index number of the nodes in the element, and store them as an element node index matrix according to the natural output order of the software. At this time, the row number index of the matrix is ​​the arrangement order number of the elements.

[0016] The stress matrix is ​​extracted by iterating through the elements based on the number of elements. The elements are arranged into a tensor matrix. The eigenvalues ​​and eigenvectors of the matrix are obtained by solving the QR eigenvalue method. The eigenvalues ​​and eigenvectors are arranged by size and stored in the order of eigenvalues ​​and eigenvector spatial components. At this time, each row in the matrix contains the magnitude and direction of the principal stress at the element integration point indexed by that row number.

[0017] A further technical solution of the present invention is: the specific post-processing operation of the stress state analysis result data is as follows:

[0018] The finite element simulation software was used to perform simulation calculations on the head structure of the wound shell of a solid rocket motor.

[0019] Output the stress state data of the model, store and output it in the software's common output format;

[0020] Load the model stress state data into the program;

[0021] Post-processing of stress state analysis results data;

[0022] Output the post-processed data and save it as a common format data storage file.

[0023] A further technical solution of the present invention is: the data storage file includes the number of nodes, coordinates, number of elements, index matrix, position, value, and direction of loads, position and method of constraints, and magnitude and direction vector of principal stresses.

[0024] A further technical solution of the present invention is: the method for generating a single principal stress line is as follows:

[0025] Select an element and use its integration point as a seed point. Based on the stress tracing scheme, start tracing its maximum or minimum principal stress line from that point.

[0026] Once the principal stress line of a seed point is generated, the candidate point closest to the initial seed point is selected as the new seed point according to the set stress trajectory distance parameter.

[0027] Repeat the above steps until all candidate points have been tracked, thus completing the integration of principal stress lines based on the stress tensor field.

[0028] A further technical solution of the present invention is: the stress tracing scheme is a method for generating a single stress trajectory;

[0029] Randomly select or specify a cell as a seed for stress line tracing;

[0030] The step size is set from the first element along the principal stress direction, and this step size ends at the next element.

[0031] The second element is reached after extending one step along the principal stress direction;

[0032] The second unit repeats the above steps until it extends to the boundary.

[0033] A further technical solution of the present invention is: the method of controlling the tracking step size using a bisection method based on a cylindrical coordinate system is as follows:

[0034] Determine cell e i The current point P in i Based on the spatial coordinates of the element, the integration point number is read and the principal stress direction of the integration point is extracted. The principal stress direction is then converted into cylindrical coordinates. Integrate the derivative to obtain the distance P. i Point, along The new integration point P with direction and arc length of step size x is tested. i+1 Determine if it is in the original cell e i Within the range, if e i Not containing P i+1 Then it is necessary to determine cell e i+1 ;

[0035] Define cell e i The adjacent cells are called neighboring cells. Further testing of P... i+1 Is it located in e? i any adjacent cell e adj In the middle, if P i+1 Not in e i or e adj Within, the step size x is reduced using the bisection method;

[0036] Until P i+1 Located in e i or e adj The subsequent integration process begins at integration point P. i+1 and containing P i+1 cell e i+1 restart.

[0037] A further technical solution of the present invention is: the method for regulating the density of principal stress line generation based on spacing control parameters is as follows:

[0038] Set the control parameter for adjusting the spacing between stress lines to m. This control parameter is the minimum number of units between stress lines.

[0039] Using the control parameter m as the minimum number of units between stress lines, the space enclosed by m units around the first stress line is defined as the "empty zone".

[0040] The unit closest to the seed outside the "empty zone" is used as the second seed to start tracing the next stress line;

[0041] Repeat the above steps until stress lines for all parts are drawn.

[0042] A further technical solution of the present invention is: the method for tracking the principal stress line based on the line type control parameters is as follows:

[0043] The linear control parameter for adjusting the seeding frequency is set to n. This linear control parameter is the number of unit intervals between adjacent units determined during stress line tracing.

[0044] Based on the linear control parameters of the seeding frequency, all cells within the area enclosed by the next cell with an interval of n cells from the original cell are defined as adjacent cells, thus controlling the number of cell intervals selected as seeding point units.

[0045] Stress lines are traced using the method for generating single principal stress lines, and new stress lines are drawn.

[0046] An electronic device includes at least one processor and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the method for visualizing the stress of the solid rocket motor winding shell head.

[0047] Beneficial effects

[0048] The beneficial effects of this invention are as follows: This invention proposes a method for visualizing the stress of a solid rocket motor winding shell head based on principal stress trajectories. Through a unique stress data post-processing workflow, principal stress line generation and density control mechanism, and linear trajectory adjustment technology, it effectively solves the problem of insufficient process guidance in stress visualization during traditional fiber winding processes. Compared with existing patents, this invention simplifies the data processing workflow, improves data compatibility and processing efficiency; it uses the eigenvalue solution method to accurately calculate the principal stress direction and introduces bisection step size control in the cylindrical coordinate system to ensure the continuity and accuracy of stress lines in high-curvature and thin-layer shell structures, solving the problem of stress line breakage when tracing stress to the thin-layer boundary in existing inventions for composite material shell thin-layer structures. Furthermore, through dynamic adjustment of spacing and linear parameters, the stress line density and arrangement are optimized, significantly improving the clarity and process guidance value of the stress visualization image. This method's standardized and efficient data processing workflow, seamlessly integrated with finite element simulation software, provides a systematic and reusable visualization tool, significantly enhancing the guidance and efficiency of process optimization and engineering design, demonstrating significant creativity and novelty.

[0049] Comparative analysis with existing stress line visualization results, such as Figure 10 As shown, traditional fiber winding processes lack process guidance for stress visualization results, and existing stress tracing methods are prone to stress line breakage in high-curvature, thin-layer structures. Furthermore, the required data processing is complex, only accepting specific .stress format files as input, lacking standardization and efficiency. This invention provides a systematic and standardized stress visualization method, using principal stress traces as a process reference for composite material shells, enhancing the process guidance significance of the results. Through eigenvalue solving and bisection step size control based on cylindrical coordinates, the accuracy and consistency of stress lines are ensured. Optimized data processing flow and stress line density control, such as… Figure 7 As shown, this improves processing efficiency and image quality. It comprehensively covers the stress distribution of the shell head structure, such as... Figure 9 As shown, it supports more precise process optimization and design improvements. Attached Figure Description

[0050] Figure 1 This is a flowchart of the data preprocessing process for stress visualization in this invention.

[0051] Figure 2 This is a flowchart of the stress state data post-processing process of the present invention.

[0052] Figure 3 This is a flowchart illustrating the input file conversion process for the stress visualization program of this invention.

[0053] Figure 4 This is a flowchart illustrating the stress visualization process of this invention.

[0054] Figure 5 This is a flowchart of the single-stress line trajectory generation process of the present invention.

[0055] Figure 6 This is a flowchart of the search step size control tracking process of the present invention.

[0056] Figure 7 This is a visual comparison chart of the stress lines for parameter control in this invention.

[0057] Figure 8 A visualization of stress lines in a homogeneous material shell.

[0058] Figure 9 This is a schematic diagram of the operation steps in an embodiment of the present invention.

[0059] Figure 10 This is a comparison chart of the effects of the present invention and existing stress visualization methods on thin-walled shell structures made of composite materials. Detailed Implementation

[0060] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0061] To address the shortcomings of existing methods for visualizing stress in solid rocket motor wound shell head structures, such as difficulties in data post-processing, lack of process guidance for fiber winding processes and thin-layer solid structures, and complex human-computer interaction, this invention provides a method for visualizing stress in solid rocket motor wound shell heads based on principal stress trajectories. The specific steps are as follows:

[0062] Step 1: Construct a finite element simulation model of the solid rocket motor winding shell head structure, perform mechanical performance simulation analysis, obtain stress state analysis results data, and perform post-processing;

[0063] Step 2: Read the stress state analysis results after processing, and based on the principal stress trace theory, use the cylindrical coordinate system as the tracking basis, use the bisection method to control the tracking step size, and generate a single principal stress line;

[0064] Step 3: Adjust the density of principal stress line generation based on spacing control parameters;

[0065] Step 4: Adjust the tracking line type of the principal stress line based on the line type control parameters, and draw a stress visualization image.

[0066] This invention can be used to visualize the principal stress trajectory of different regions and winding layers of a head, obtain a stress distribution trajectory diagram of the head structure, and analyze the influence of different regions, winding line type, yarn size, winding angle and other winding process parameters and different head reinforcement processes on the stress distribution of the head. It provides guidance and direct reference for the design, manufacturing, optimization and reinforcement of solid rocket engine winding shell head structure.

[0067] The above technical solution will be further described below with reference to the accompanying drawings and specific embodiments. The intermediate transition parameters, functions, and matrices designed in the following steps are all examples, including but not limited to the following naming conventions:

[0068] Reference Figure 1 As shown, this embodiment includes a preprocessing flow for stress visualization data of a solid rocket motor wound shell head structure. This invention interfaces with commonly used commercial finite element analysis software, such as ABAQUS. It uses the common output format file of this commercial software as the initial file, performs post-processing on the output data, and finally organizes it into a universal format data storage file as the input file for stress visualization. This embodiment uses ABAQUS finite element analysis software as an example, as the simulation analysis software. It uses its common output format file (.rpt format file) as an example, as the data output file. It uses the universal format data storage file, .stress format file, as an example, as the output file for the stress visualization scheme. The specific steps are as follows:

[0069] Step 1: Use the commercial ABAQUS finite element simulation software to complete the simulation calculation of the solid rocket motor winding shell head structure.

[0070] Step 2: Output the stress state data of the model and save it as a .rpt format file.

[0071] Step 3: Load the model stress state data into the program.

[0072] Step 4: Post-process the stress state data.

[0073] Step 5: Output the post-processed data as a .stress format file.

[0074] Reference Figure 2As shown, post-processing is performed on the stress state data. The stress state data output from commercial software typically includes the magnitudes of principal stresses at nodes and element integration points, as well as the magnitudes of Cartesian stresses. However, this embodiment also requires the direction vectors of the principal stresses at each element integration point in Cartesian coordinates. Therefore, the stress state data output from the commercial software needs to be reprocessed. The eigenvalue method is used to solve for the stress tensor matrix at each element integration point to calculate the required input stress data. This embodiment uses the commercial software ABAQUS as an example for data simulation and output, with the output data file format .rpt as an example. The specific steps are as follows:

[0075] Step 1: Read the element integration point stress from the .rpt format file and store it as a stress matrix.

[0076] Step 2: Read the cell node index data and node coordinate data from the .rpt format file and store them as eleids and nodes matrices.

[0077] Step 3: Iterate through the stress matrix and output the stress data of each element integration point as a p matrix. Use the eigenvalue method to obtain the magnitude and direction of the three principal stresses at each element integration point.

[0078] Reference Figure 3 As shown, the output post-processed data is a general-format data storage file. This embodiment uses a .stress format file as an example and uses MATLAB software for programming. Since the .stress format file has its fixed format and corresponding syntax, the processed data is output according to the file format for easy subsequent use. The specific steps are as follows:

[0079] Step 1: Create and open a .stress format file to output the dimensional search keywords and the unit search keywords.

[0080] Step 2: Output the node search keywords, the number of nodes, and the node coordinate data.

[0081] Step 3: Output the unit search keywords, output the number of units, and output the unit index data under the new node matrix based on the unit index matrix.

[0082] Step 4: Output node load search keywords and output node load data.

[0083] Step 5: Output node constraint search keywords and output node constraint data.

[0084] Step 6: Output Cartesian stress search keywords, and output the magnitudes of the three principal stresses and the vector data of the principal stress directions.

[0085] Step 7: Close the .stress file.

[0086] The specific steps of the post-processing method for the stress state analysis results data are as follows:

[0087] Step 1: Simplify the stress state analysis results data, that is, output the element integral point stress and nodal coordinate data of the shell split structure to be processed from the simulation results, and store them as a general format data storage file;

[0088] Step 2: Read the stress magnitude of the integration point in the tapered shell reduced integration element from the data storage file, set each row as an element according to the element index number, and store it as a stress matrix according to the natural output order of the software. At this time, the row index of the matrix is ​​the arrangement order number of the elements.

[0089] Step 3: Read the cone-shell reduced integral element node index data and node coordinate data from the data storage file. Set each row as an element according to the x, y, z coordinates of the element nodes, and store it as a node matrix according to the natural output order of the software. At this time, the row number index of the matrix is ​​the node number index. Set each row as an element according to the index number of the nodes in the element, and store it as an element node index matrix according to the natural output order of the software. At this time, the row number index of the matrix is ​​the arrangement order number of the elements.

[0090] Step 4: Iterate through the stress matrix based on the number of elements, extract the elements from the stress matrix and arrange them into a tensor matrix. Use the QR eigenvalue solution method to obtain the eigenvalues ​​and eigenvectors of the matrix. Arrange them according to their size and store them as a matrix in the order of eigenvalues ​​and eigenvector spatial components. At this time, each row in the matrix contains the magnitude and direction of the principal stress at the element integration point indexed by that row number.

[0091] Reference Figure 4 As shown, a stress visualization method based on principal stress trajectories is presented. The foundation of this method for visualizing the stress tensor is the generation of individual stress trajectories. To address the influence of thin-layer structures on the normal principal stress trajectories in shell head structures, element integration points are selected, and an element-by-element tracing approach is used to implement the stress visualization method based on principal stress trajectories.

[0092] Specifically, the method for generating a single principal stress line in step two is as follows:

[0093] Step 1: Select an element and use its integration point as the seed point. Based on the stress tracing scheme, start tracing its maximum or minimum principal stress line from that point.

[0094] Step 2: Once the principal stress line of a seed point is generated, select the candidate point closest to the initial seed point as the new seed point according to the set stress trajectory distance parameter.

[0095] Step 3: Repeat Step 1 until no candidate points are available, thus achieving the integration of principal stress lines based on the stress tensor field.

[0096] Reference Figure 5 As shown, the stress tracing scheme is a method for generating a single stress trajectory: First, a cell within the model is randomly selected or specified as the seed for stress line tracing. A step size is set from the first cell along the principal stress direction, ending at the next cell. Then, the step size is extended along the principal stress direction by one step size to reach the second cell. This operation is repeated in the second cell until the cell at the model boundary is reached. The specific steps are as follows:

[0097] Step 1: Randomly select or specify an element as the seed element for stress line tracing.

[0098] Step 2: Set the tracking step size along the principal stress direction from the first element.

[0099] Step 3: Extend one step length along the principal stress direction to reach the second element.

[0100] Step 4: Repeat steps 2 and 3 for the second unit, and so on until the boundary.

[0101] Reference Figure 6 As shown, the method of using a cylindrical coordinate system as the tracking basis and controlling the tracking step size using the bisection method is as follows: Since this invention is for composite material wound shells, the model is approximately axisymmetric. Existing stress tracking methods are prone to tracking to the boundary in high curvature, thin-layer structures. Therefore, this invention uses the cylindrical coordinate system bisection method to track stress, ensuring the continuity of stress lines. In the stress tracking process, taking this as an example: with the controllable variable x as the step size, the principal stress line is moved from cell e... i The current point P in i Integrate to a new point P i+1 The specific steps are as follows:

[0102] Step 1: Determine cell e i The current point P in i Based on the spatial coordinates of the element, the integration point number is read and the principal stress direction of the integration point is extracted. The principal stress direction is then converted into cylindrical coordinates. Integrate the derivative to obtain the distance P. i Point, along The new integration point P with direction and arc length of step size x is tested. i+1 Determine if it is in the original cell e i Within the range, if e i Not containing P i+1 Then it is necessary to determine cell e i+1 ;

[0103] Step 2: Example definition of cell e i The adjacent cells are called neighboring cells. Further testing of P... i+1 Is it located in e? i any adjacent cell e adj In the middle, if P i+1 Not in e i or e adj Within, the step size x is reduced using the bisection method;

[0104] Step 3: Until P i+1 Located in e i or e adj The subsequent integration process begins at integration point P. i+1 and containing P i+1 cell e i+1 restart.

[0105] Reference Figure 7 As shown, this invention describes a method for controlling the density of principal stress line generation based on spacing control parameters. The invention sets three control parameters: directly affecting the stress line tracking angle by changing the seed unit's density; directly affecting the distance between stress lines by changing the production spacing of the stress lines; and directly affecting the thickness of the stress lines by changing their relative width. This achieves multi-angle, multi-layered, and diversified display effects.

[0106] The specific steps are as follows:

[0107] Step 1: Set the seeding frequency control parameters.

[0108] Step 2: Control the number of intervals between the selected elements of the seeding points.

[0109] Step 3: Set the control parameters for adjusting the spacing between stress lines.

[0110] Step 4: Based on the control parameters, the space around the first generated stress line at a specified distance is designated as the "empty zone".

[0111] Step 5: Using the cell closest to the seed outside the "empty band" as the second seed, start tracing the next stress line.

[0112] Step 6: Repeat steps two and three until the stress lines for all parts are drawn.

[0113] Step 7: Set the stress line width adjustment parameters.

[0114] Step 8: Using the control parameters from Step 3 as a reference, calculate the scaling factor of the stress line width through the "empty zone" parameter.

[0115] Reference Figure 8As shown, stress visualization based on stress trajectories is achieved for a homogeneous material shell. This embodiment uses a shell structure made of homogeneous aluminum material and analyzes it using stress visualization technology.

[0116] This embodiment uses a φ480mm shell size as an example. The specific steps are as follows:

[0117] Step 1: Create a three-dimensional model of the shell and apply predetermined load conditions to the model.

[0118] Step 2: Use finite element analysis software to perform stress analysis on the model and obtain stress distribution data of the shell under internal pressure load conditions.

[0119] Step 3: Post-process the stress state analysis results of the homogeneous material shell head structure. Obtain the magnitude and direction of the principal stresses at the element integration points.

[0120] Step 4: Read the data, and generate a single principal stress line based on the principal stress trace theory and the bisection method to control the tracking step size.

[0121] Step 5: Generate all principal stress lines based on the control parameters.

[0122] Step 6: Based on the control parameter adjustment, users can ultimately control the display effect of stress lines by adjusting the parameters.

[0123] Reference Figure 9 As shown in the figure, the specific operation steps of the method for visualizing the stress of the wound shell head of a solid rocket motor based on the principal stress trace are as follows:

[0124] Based on the specific operating methods described in the above-described embodiments, taking a φ480mm shell as an example, the fiber winding angle is 23.5°, and the shell is wound with two longitudinal winding layers and four circumferential winding layers. Each longitudinal winding layer consists of two layers with a radial winding angle along the meridional plane of the shell. The specific implementation steps are as follows:

[0125] Step 1: Refer to Figure 9 Figure a shows how a three-dimensional model of the shell is created using commercial finite element analysis software, and how predetermined load conditions are applied to the model.

[0126] Step 2: Refer to Figure 9 Figure b shows the stress analysis performed on the model using finite element analysis software.

[0127] Step 3: Refer to Figure 9 Figure c shows the stress distribution data of the shell under internal pressure load conditions.

[0128] Step 4: Post-process the stress state analysis results of the homogeneous material shell head structure. Obtain the magnitude and direction of the principal stresses at the element integration points. (Refer to...) Figure 9 In the middle d diagram, for ease of display, the principal stress direction distribution diagram of the element integration point can be output here for reference and comparison.

[0129] Step 5: Read the data, and based on the principal stress trace theory and the bisection method, track the step size in the cylindrical coordinate system to generate a single principal stress line.

[0130] Step 6: Generate all principal stress lines based on the stress line spacing control parameters.

[0131] Step 7: Refer to Figure 9 In the Zhonge diagram, based on the adjustment of stress line type control parameters, users can ultimately control the display effect of stress lines by adjusting the parameters.

[0132] Reference Figure 10 As shown, this embodiment compares existing stress visualization methods with solid rocket motor winding shells, i.e. thin-walled structures, and uses a conical shell element model to compare the stress visualization effects.

[0133] It is clear that the images from existing stress visualization methods exhibit obvious stress line breaks, discontinuities, and sparseness, making it impossible to provide guidance or optimization for processing techniques based on the stress state. The stress state display is not intuitive, indicating that existing stress visualization methods are not suitable for thin-walled structures of composite material shells. Furthermore, their limitations on input files prevent some commercial software from directly using their data interfaces.

[0134] In this embodiment, the stress visualization method of the present invention presents images with obvious stress line continuity, appropriate density, and completeness of the wrapping around the axisymmetric shell. It can guide and optimize the winding and laying processes of composite material shells, and can intuitively display their stress state. At the same time, the data structure is optimized and can be compatible with the data output of various commercial software.

[0135] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for visualizing the stress in the end cap of a solid rocket motor's wound casing, characterized in that... The specific steps are as follows: A finite element simulation model of the solid rocket motor wound shell head structure was constructed, and mechanical performance simulation analysis was performed. Stress state analysis results were obtained and post-processed. The post-processing method for the stress state analysis results is as follows: The stress state analysis results are simplified by outputting the element integral point stress and node coordinate data of the shell split structure to be processed from the simulation results and storing them as a general format data storage file. Read the stress magnitudes at the integration points in the reduced integration elements of the conical shell from the data storage file, set each row as an element according to the element index number, and store it as a stress matrix according to the natural output order of the software. At this time, the row index of the matrix is ​​the arrangement order number of the elements. Read the cone-shell reduced integral element node index data and node coordinate data from the data storage file. Set each row as an element according to the x, y, z coordinates of the element nodes, and store them as a node matrix according to the natural output order of the software. At this time, the row number index of the matrix is ​​the node number index. Set each row as an element according to the index number of the nodes in the element, and store them as an element node index matrix according to the natural output order of the software. At this time, the row number index of the matrix is ​​the arrangement order number of the elements. The stress matrix is ​​extracted by iterating through the elements based on the number of elements and arranged into a tensor matrix. The eigenvalues ​​and eigenvectors of the matrix are obtained by solving the QR eigenvalue method. The eigenvalues ​​and eigenvectors are arranged by size and stored in the order of eigenvalues ​​and eigenvector spatial components. At this time, each row in the matrix contains the magnitude and direction of the principal stress at the element integration point indexed by that row number. After reading the processed stress state analysis data, based on the principal stress trace theory and using a cylindrical coordinate system as the tracking basis, a single principal stress line is generated by controlling the tracking step size using the bisection method. The method for generating a single principal stress line is as follows: Select an element and use its integration point as a seed point. Based on the stress tracing scheme, start tracing its maximum or minimum principal stress line from that point. Once the principal stress line of a seed point is generated, the candidate point closest to the initial seed point is selected as the new seed point according to the set stress trajectory distance parameter. Repeat the above steps until all candidate points have been tracked, thus completing the integration of principal stress lines based on the stress tensor field. The method of using cylindrical coordinates as the tracking basis and the bisection method to control the tracking step size is as follows: Determine cell Current point in Based on the spatial coordinates of the element, the integration point number is read and the principal stress direction of the integration point is extracted. The principal stress direction is then converted into cylindrical coordinates. Integrate the derivative to obtain the distance. Point, along The new integration point is in the direction of the arc with a step length of x. Determine if it is in the original cell Within the range, if Not included Then it is necessary to determine the cell. ; Define cell The adjacent cells are called neighboring cells; further testing is needed. Is it located in any adjacent cells In the middle, if Not here or Within, the step size x is reduced using the bisection method; until lie in or Inside, the subsequent integration process is based on the integration point. and contain cell restart; The density of principal stress line generation is adjusted based on spacing control parameters; the method for adjusting the density of principal stress line generation based on spacing control parameters is as follows: Set the control parameter for adjusting the spacing between stress lines to m. This control parameter is the minimum number of units between stress lines. Using the control parameter m as the minimum number of units between stress lines, the space enclosed by m units around the first stress line is defined as the "empty zone". The unit closest to the seed outside the "empty zone" is used as the second seed to start tracing the next stress line; Repeat the above steps until stress lines for all parts are drawn; The method for adjusting the tracking line type of the principal stress line based on the line type control parameters is as follows: The linear control parameter for adjusting the seeding frequency is set to n. This linear control parameter is the number of unit intervals between adjacent units determined during stress line tracing. Based on the linear control parameters of the seeding frequency, all cells within the area enclosed by the next cell with an interval of n cells from the original cell are defined as adjacent cells, thus controlling the number of cell intervals selected as seeding point units. Stress lines are traced using the method for generating single principal stress lines, and new stress lines are drawn.

2. The method for visualizing the stress of the end cap of a solid rocket motor winding casing according to claim 1, characterized in that: The specific post-processing operation for the stress state analysis results data is as follows: The finite element simulation software was used to perform simulation calculations on the head structure of the wound shell of a solid rocket motor. Output the stress state data of the model, store and output it in the software's common output format; Load the model stress state data into the program; Post-processing of stress state analysis results data; Output the post-processed data and save it as a common format data storage file.

3. The method for visualizing the stress of the end cap of a solid rocket motor winding casing according to claim 2, characterized in that: The data storage file includes the number of nodes, coordinates, number of elements, index matrix, location, value, and direction of loads, location and method of constraints, and magnitude and direction vector of principal stresses.

4. The method for visualizing the stress of the winding shell head of a solid rocket motor according to claim 3, characterized in that: The stress tracing scheme is a method for generating a single stress trajectory; Randomly select or specify a cell as a seed for stress line tracing; The step size is set from the first element along the principal stress direction, and this step size ends at the next element. The second element is reached after extending one step along the principal stress direction; The second unit repeats the above steps until it extends to the boundary.

5. An electronic device, characterized in that: The method includes at least one processor and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the method for visualizing the stress of the wound shell head of a solid rocket motor according to any one of claims 1-4.

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