A finite element mesh model generation method and system for a solid engine casing

Abstract

The present invention discloses a method and system for generating a finite element mesh model of a solid motor casing, which relates to the technical field of finite element model construction. The method includes the following steps: performing axial compression load analysis on the solid motor casing to construct a finite element mesh surface of the solid motor casing cross section; rotating the finite element mesh surface of the solid motor casing cross section by a preset angle based on the central axis of the solid motor casing to obtain a finite element mesh unit body of the solid motor casing cross section; after defining the unit body discrete coordinate system and the unit body fiber winding angle; repeatedly rotating the finite element mesh unit body of the solid motor casing cross section by a preset angle based on the central axis until it coincides with the finite element mesh surface of the solid motor casing cross section, thereby obtaining a finite element mesh model of the solid motor casing. The present invention can obtain a finite element mesh model suitable for a solid motor casing whose load-bearing portion is anisotropic material.

Description

Technical Field

[0001] The present invention relates to the technical field of finite element model construction, and in particular to a method and system for generating a finite element mesh model of a solid engine casing. Background Art

[0002] Understanding the response of solids under axial loading is crucial in engineering design and structural analysis. For example, to ensure the stability of solid rocket motors during transport and launch, it is necessary to accurately predict the behavior of solids. Researchers have developed a three-dimensional axial compression solid algorithm to simulate the stress distribution, deformation, and failure mode of solids under loading. The three-dimensional axial compression solid algorithm plays an important role in engineering and science, primarily used to simulate and analyze the mechanical behavior of three-dimensional solids under axial loading (e.g., compression).

[0003] The existing algorithms are not accurate enough in calculating the axial compression buckling failure of thin-walled pressure vessels, including solid rocket engine casings, during the computational process. This is because the load-bearing parts are usually made of anisotropic materials. Therefore, it is urgent to study the meshing methods to avoid the mesh incompatibility caused by general meshing algorithms. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for generating a finite element mesh model of a solid motor casing, which can effectively complete the construction of the finite element mesh model of the solid motor casing.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] In one aspect, the present invention provides a method for generating a finite element mesh model of a solid motor casing, wherein the solid motor casing includes a barrel section and two head sections located on both sides of the barrel section, wherein a polar hole is formed on the head section at a position away from the center of the barrel section; the finite element mesh model generation method comprises the following steps:

[0007] An axial compression load analysis is performed on the solid motor case to construct a finite element mesh surface of the solid motor case cross section; the finite element mesh surface of the solid motor case cross section includes the finite element mesh surface of the skirt inner wrapping layer, the finite element mesh surface of the metal skirt, the finite element mesh surface of the rubber layer, and the finite element mesh surface of the skirt outer wrapping layer; any finite element mesh surface is composed of a number of discrete points.

[0008] Based on the central axis of the solid motor case, the finite element mesh surface of the solid motor case cross section is rotated by a preset angle to obtain a finite element mesh unit body of the solid motor case cross section; the finite element mesh unit body of the solid motor case cross section includes a plurality of mesh unit bodies; the central axis is a line connecting the polar holes on the two head sections; the preset angle is divisible by 360.

[0009] For any grid cell, the cell discrete coordinate system and the cell fiber winding angle are defined.

[0010] Based on the central axis of the solid engine case, the finite element mesh unit body of the solid engine case cross section is repeatedly rotated at a preset angle until it coincides with the finite element mesh surface of the solid engine case cross section, thereby obtaining a finite element mesh model of the solid engine case; the finite element mesh model of the solid engine case is composed of multiple finite element mesh unit bodies of the solid engine case cross section.

[0011] On the other hand, the present invention also provides a finite element mesh model generation system for a solid motor casing, which is used to implement the finite element mesh model generation method for a solid motor casing as described above.

[0012] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0013] The present invention provides a method and system for generating a finite element mesh model of a solid motor casing. The method comprises the following steps: performing an axial compressive load analysis on the solid motor casing to construct a finite element mesh surface of the solid motor casing cross section; rotating the finite element mesh surface of the solid motor casing cross section by a preset angle based on the central axis of the solid motor casing to obtain a finite element mesh unit body of the solid motor casing cross section; defining a unit discrete coordinate system and a unit fiber winding angle for each mesh unit body; and repeatedly rotating the finite element mesh unit body of the solid motor casing cross section by a preset angle based on the central axis of the solid motor casing until the unit body coincides with the finite element mesh surface of the solid motor casing cross section to obtain a finite element mesh model of the solid motor casing. The present invention comprehensively considers factors such as the initial geometric defects of the casing, the form of structural deformation, and the calculation accuracy. The structure of the solid motor casing subjected to axial compressive load is discretized layer by layer, and the cross section finite element mesh surface is rotated and swept to construct a finite element mesh model of the solid motor casing suitable for the load-bearing portion of the solid motor casing made of anisotropic material. This facilitates the simulation and analysis of the mechanical behavior of three-dimensional entities under axial loading. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1A schematic structural diagram of a solid motor casing in a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0016] Figure 2 A simplified structural schematic diagram of a solid motor casing in a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0017] Figure 3 This is a flow chart of a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0018] Figure 4 This is a specific flow chart of step A1 in a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0019] Figure 5 A schematic diagram of the shell thickness in a method for generating a finite element mesh model of a solid motor shell provided in Example 1 of the present invention;

[0020] Figure 6 A schematic diagram of a discrete shell core mold outline in a method for generating a finite element mesh model of a solid motor shell provided in Example 1 of the present invention;

[0021] Figure 7 A schematic diagram of the outer contour of a discrete spirally wound layer in a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0022] Figure 8 A schematic diagram of the outer contour of a discrete circumferential winding layer in a finite element mesh model generation method for a solid motor casing provided in Example 1 of the present invention;

[0023] Figure 9 A schematic diagram of the contour lines of the discrete metal skirt in a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0024] Figure 10 A schematic diagram of the contour lines of the discrete rubber layer in a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0025] Figure 11 A schematic diagram of the first layer outline of the discrete skirt outer winding layer in a finite element mesh model generation method for a solid motor casing provided in Example 1 of the present invention;

[0026] Figure 12 A schematic diagram of the outer contour of a discrete skirt outer wrapping layer (full paving) in a finite element mesh model generation method for a solid motor casing provided in Example 1 of the present invention;

[0027] Figure 13 A schematic diagram of the outer contour of the discrete skirt outer wrapping layer reinforcement layer in a finite element mesh model generation method for a solid motor casing provided in Example 1 of the present invention;

[0028] Figure 14 A schematic diagram of a rotational sweep in a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0029] Figure 15 A schematic diagram of a unit discrete coordinate system and a unit fiber winding angle in a finite element mesh model generation method for a solid motor casing provided in Example 1 of the present invention;

[0030] Figure 16 A schematic diagram of the relationship between the radius r of the parallel circle of the casing head and the coordinate z of the axis of rotation in a finite element mesh model generation method for a solid motor casing provided in Example 1 of the present invention;

[0031] Figure 17 A schematic diagram of C3D8 unit replication in a finite element mesh model generation method for a solid motor casing provided in Example 1 of the present invention;

[0032] Figure 18 A schematic diagram of C3D6 unit replication in a finite element mesh model generation method for a solid motor casing provided in Example 1 of the present invention;

[0033] Figure 19 A schematic diagram of a finite element mesh model in a method for generating a finite element mesh model of a solid motor casing provided in Example 1 of the present invention;

[0034] Figure 20 This is a structural block diagram of a finite element mesh model generation system for a solid motor casing provided in Example 2 of the present invention;

[0035] Figure 21 This is a diagram of the internal structure of a computer device provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The purpose of the present invention is to provide a method and system for generating a finite element mesh model of a solid engine casing, aiming to construct a finite element mesh model suitable for a solid engine casing whose load-bearing part is anisotropic material.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] In this embodiment, a finite element mesh model generation method of a solid engine casing is described as follows: Figure 1 As shown in the structural diagram, the solid rocket case consists of a barrel section and two head sections located on either side of the barrel section. A polar hole is provided in the head section, away from the center of the barrel section. Taking into account factors such as the case's initial geometric defects, structural deformation patterns, and computational accuracy, this embodiment uses three-dimensional solid elements as the basic unit to construct a 3D fine finite element analysis model of the case. C3D8R elements are selected to represent the case's main structures, such as the inner / outer skirt wrapping layers and the metal skirt. C3D6 elements are used to represent the case's wrapping layer boundary transition sections, such as the rubber layer.

[0041] Considering the contribution of each component to the load and the mechanical response characteristics under the action of axial compression load, the model structure of the shell is simplified as follows: the components that bear the axial compression load are mainly the winding layer, metal skirt and overlap rubber. The metal joints, insulation layer rubber, plugging cover and other structures are not considered in the geometric model; the stress relief groove structure of the metal skirt is not considered, and the metal skirt structure is simplified as follows: Figure 2 The axisymmetric distribution structure shown is symmetrical along the X axis in the figure.

[0042] like Figure 3 As shown in the flowchart, the method of this embodiment includes the following steps:

[0043] A1. Perform axial compression load analysis on the solid rocket shell and construct the finite element mesh surface of the solid rocket shell cross section. The finite element mesh surface of the solid rocket shell cross section includes the finite element mesh surface of the skirt inner wrapping layer, the finite element mesh surface of the metal skirt, the finite element mesh surface of the rubber layer and the finite element mesh surface of the skirt outer wrapping layer. Any finite element mesh surface is composed of a number of discrete points. Figure 4 In the flowchart shown, step A1 specifically includes the following steps:

[0044] A11. Obtain the thickness of the single-layer winding layer of the barrel section, and use the cubic spline formula method to calculate the thickness of the single-layer winding layer at any position of the head section. Figure 5As shown in the figure, the shell head section has a variable thickness structure, that is, the thickness gradually increases from the barrel section to the part close to the pole hole. Specifically, the thickness of a single layer of winding layer at any position of the head section is calculated according to the following formula:

[0045] t f (r i )=m1×r i 0 +m2×r i 1 +m3×r i 2 +m4×r i 3 .

[0046] Among them, r i is the radius of the parallel circle at any position of the head section; m1, m2, m3 and m4 are the unknown coefficients of the cubic spline formula method.

[0047] In order to solve the unknown coefficients m1, m2, m3 and m4, four boundary conditions are required, namely:

[0048] (a) The thickness of the head at the pole hole is the highest.

[0049] (b) The thickness at twice the bandwidth is equal.

[0050] (c) The derivatives at twice the bandwidth are equal.

[0051] (d) The fiber volume remains unchanged within the double bandwidth range.

[0052] The unknown coefficients m1, m2, m3 and m4 can be solved according to the following formula:

[0053]

[0054]

[0055] Among them, r0 is the radius of the polar hole; b is the width of the fiber yarn; r b is the radius of the parallel circle at the position of one bandwidth; r 2b is the radius of the parallel circle at the position of twice the bandwidth; t R is the thickness of the winding layer of the barrel section; R is the radius of the barrel section; α0 is the diameter of the pole hole; m0 is the number of fiber yarns at the pole hole position; m R is the number of fiber yarn sheets in the barrel section; n R is the number of spiral winding layers of the barrel section; t p is the thickness of the single-layer winding layer of the barrel section; d is the differential symbol.

[0056] For the thickness prediction formula of the shell head beyond twice the bandwidth from the polar hole, due to the principle that the total amount of fiber at each position of the head section is equal to the total amount of fiber at the barrel, the thickness prediction formula beyond twice the bandwidth is obtained:

[0057]

[0058] Where w is the width of the fiber yarn. The thickness of the inner and outer layers of the skirt of the shell body are both initial given values ​​and do not need to be calculated.

[0059] In this embodiment, before generating discrete points of each layer, the following steps are also included:

[0060] Construct the discrete point array of the solid motor casing, the discrete point array of the inner winding layer of the skirt, the discrete point array of the metal skirt, the discrete point array of the rubber layer and the discrete point array of the outer winding layer of the skirt.

[0061] Initialize the solid engine casing discrete point array Node, the skirt inner winding layer discrete point array nodnum_1, the metal skirt discrete point array nodnum_2, the rubber layer discrete point array nodnum_3, and the skirt outer winding layer discrete point array nodnum_4. The purpose of storing the number pairs in the arrays nodnum_1, nodnum_2, nodnum_3, and nodnum_4 is to facilitate indexing of node numbers when generating units successively. For ease of explanation, the attached figure shows relatively few discrete points. In actual application, to ensure accuracy, sufficient discrete points are required.

[0062] Table 1 Node array format

[0063] Numbering sequence horizontal axis vertical axis vertical coordinate 1 <![CDATA[x1]]> <![CDATA[y1]]> <![CDATA[z1]]> 2 <![CDATA[x2]]> <![CDATA[y2]]> <![CDATA[z2]]> …

[0064] Table 2 Format of nodnum_1 / 2 / 3 / 4 array

[0065]

[0066] A12. Based on the thickness of a single layer of winding layer, generate discrete points of each contour line of the inner skirt winding layer, and construct a finite element mesh surface of the inner skirt winding layer. When generating the discrete points of each contour line of the inner skirt winding layer, add the spatial position of each discrete point to the solid engine shell discrete point array in sequence, and store the number of each discrete point in the inner skirt winding layer discrete point array according to the order of the contour line; the number of columns of the inner skirt winding layer discrete point array is the same as the number of discrete points on a single contour line of the inner skirt winding layer; the number of rows of the inner skirt winding layer discrete point array is the same as the number of contour lines of the inner skirt winding layer. Step A12 specifically includes the following steps:

[0067] Step A121, discrete shell core mold outline, and generate a series of number pair information and coordinate information from left to right. The winding layer is generated by winding on the core mold, and the inner edge of the skirt winding layer is closely attached to the core mold outline, so the skirt winding layer can use the discrete shell core mold outline as the starting point. Figure 6 As shown in the example, for the discrete shell core mold contour, the overall node number and coordinates of each point are stored in Node, and the number pair information is stored in nodnum_1. (The first number in the number pair indicates the position of the point on a specific layer of the contour, and the second number indicates the position on the overall node. For example, (2,19) indicates that the point is the second point on a specific layer and the 19th point on the overall node.)

[0068] Step A122: Based on the previous contour, generate the thickness of the single layer of the spiral winding layer, and superimpose the single layer thickness in the outer normal direction of each scattered point of the previous contour to obtain the outer contour of the spiral winding layer, such as Figure 7 Similarly, store the overall node number and coordinates of each point in Node, and store the number pair information in nodnum_1.

[0069] Step A123: If the next layer is spirally wound, repeat step 2; if the next layer is hoop-wound, repeat step 2. Figure 8 As shown, based on the previous outline, the thickness of the hoop winding layer is generated. The thickness of the single layer is superimposed on the outer normal direction of each scattered point in the previous outline to obtain the outer contour of the hoop winding layer. Transition regions are set at the left and right ends of the hoop winding layer to prevent the fiber single layer from hanging. Similarly, the overall node number and coordinates of each point are stored in Node, and the number pair information is stored in nodnum_1.

[0070] Step A124: Repeat steps A122 to A123 until the contour lines of the inner winding layer of the skirt are completely discrete.

[0071] A13. Based on the finite element mesh surface of the inner winding layer of the skirt, generate discrete points of each contour line of the metal skirt to construct the finite element mesh surface of the metal skirt. When generating the discrete points of each contour line of the metal skirt, add the spatial position of each discrete point to the solid engine casing discrete point array in sequence, and store the number of each discrete point in the metal skirt discrete point array according to the order of the contour line; the number of columns of the metal skirt discrete point array is the same as the number of discrete points on a single contour line of the metal skirt; the number of rows of the metal skirt discrete point array is the same as the number of contour lines of the metal skirt. Assuming that the finite element mesh surface of the inner winding layer of the skirt generates 1000 discrete points, the numbering of the metal skirt discrete points starts from 1001. Figure 9 As shown, after dividing the thickness of each designed layer equally to obtain the average thickness of each layer, the length of the left side is used to calculate the number n, and the metal skirt is divided into n layers along the thickness direction. Step A13 specifically includes the following steps:

[0072] Step A131: Discretize the first layer outline of the metal skirt and generate a series of number pair information and coordinate information from the left end to the right end.

[0073] Step A132: Discretize the second layer outline of the metal skirt and generate a series of number pair information and coordinate information from the left end to the right end.

[0074] Step A13n: Discretize the nth layer of the metal skirt and generate a series of number pairs and coordinate information from the left end to the right end. During these steps, store the overall node number and coordinates of each discrete point in Node, and sequentially store the number pairs in the array nodnum_2.

[0075] A14. Based on the finite element mesh surface of the inner winding layer of the skirt and the finite element mesh surface of the metal skirt, generate discrete points of each contour line of the rubber layer to construct the finite element mesh surface of the rubber layer. When generating the discrete points of each contour line of the rubber layer in step A14, add the spatial position of each discrete point to the discrete point array of the solid engine casing in sequence, and store the number of each discrete point in the rubber layer discrete point array according to the order of the contour line; the number of columns of the rubber layer discrete point array is the same as the number of discrete points on a single contour line of the rubber layer; the number of rows of the rubber layer discrete point array is the same as the number of contour lines of the rubber layer. Assuming that the finite element mesh surface of the metal skirt generates 1000 discrete points, then based on the finite element mesh surface of the inner winding layer of the skirt and the finite element mesh surface of the metal skirt, the discrete points in the rubber layer start from 2001. Initialize the number pair array nodnum_3 and divide the rubber into n layers of contours along the thickness direction. As Figure 10 As shown, some nodes of the rubber layer, the metal skirt, the inner winding layer of the skirt, and the outer winding layer of the skirt have common nodes, and the generated nodes are uniformly represented by m; step A14 specifically includes the following steps:

[0076] Step A141: Discretize the contour of the first layer of the rubber layer and generate a series of number pair information and coordinate information from the left end to the right end.

[0077] Step A142: Discretize the contour of the second layer of the rubber layer and generate a series of number pair information and coordinate information from the left end to the right end.

[0078] Step A14n: Discretize the contour of the nth rubber layer and generate a series of number pairs and coordinate information from left to right. During these steps, store the overall node number and coordinates of each discrete point in Node, and sequentially store the number pairs in the array nodnum_3.

[0079] A15. Based on the finite element mesh surface of the inner skirt wrapping layer and the finite element mesh surface of the rubber layer, and based on the thickness of the single-layer wrapping layer, generate discrete points for each contour line of the outer skirt wrapping layer, and construct the finite element mesh surface of the outer skirt wrapping layer. When generating the discrete points for each contour line of the outer skirt wrapping layer, the spatial position of each discrete point is sequentially added to the solid engine casing discrete point array, and the number of each discrete point is stored in the outer skirt wrapping layer discrete point array according to the order of the contour line; the number of columns of the outer skirt wrapping layer discrete point array is the same as the number of discrete points on a single contour line of the outer skirt wrapping layer; the number of rows of the outer skirt wrapping layer discrete point array is the same as the number of contour lines of the outer skirt wrapping layer. Assuming that 1000 discrete points are generated for the rubber layer, then based on the finite element mesh surface of the inner skirt wrapping layer, the finite element mesh surface of the rubber layer, and the finite element mesh surface of the metal skirt, the rubber discrete points start from 3001. Initialize the number pair array nodnum_4; step A15 specifically includes the following steps:

[0080] Step A151: Figure 11 As shown, the first layer of the outer skirt wrapping layer is discretized and a series of number pairs and coordinate information is generated from the left end to the right end. The overall node number and coordinates of each point are stored in Node, and the number pair information is stored in nodnum_4.

[0081] Step A152: Figure 12 As shown in the figure, based on the previous outline, the outer contour of the skirt wrapping layer (full paving) is discretized. Similarly, the overall node number and coordinates of each point are stored in Node, and the number pair information is stored in nodnum_4.

[0082] Step A153: If the next layer is a skirt wrapping layer (full paving), repeat step A152; if the next layer is a reinforcement layer, repeat step A153. Figure 13 As shown in the figure, based on the previous outline, the outer contour of the reinforcement layer is discretized. Similarly, the overall node number and coordinates of each point are stored in Node, and the number pair information is stored in nodnum_4.

[0083] Step A154: Repeat steps A152 and A153 until the contour points of the outer wrapping layer of the skirt are discretized.

[0084] A16. The finite element mesh of the solid rocket motor case cross section is constructed based on the finite element mesh of the inner skirt wrapping layer, the metal skirt, the rubber layer, and the outer skirt wrapping layer. The finite element mesh of the inner skirt wrapping layer has overlapping contours with the finite element mesh of the rubber layer and the outer skirt wrapping layer; the finite element mesh of the rubber layer has overlapping contours with the finite element mesh of the metal skirt and the outer skirt wrapping layer.

[0085] A2. Based on the central axis of the solid motor case, the finite element mesh surface of the solid motor case cross section is rotated by a preset angle to obtain a finite element mesh unit body of the solid motor case cross section; the finite element mesh unit body of the solid motor case cross section includes a plurality of mesh unit bodies; the central axis is the line connecting the polar holes on the two head segments; the preset angle is divisible by 360; such as Figure 14 As shown, the side surface is a finite element mesh surface of a solid engine case cross section, which is swept around the rotation axis. Each time a preset angle is rotated, a finite element mesh unit body of the solid engine case cross section can be obtained.

[0086] A3. For any grid unit body, define the unit body discrete coordinate system and unit body fiber winding angle of the grid unit body. Specifically in this embodiment, if Figure 15 As shown, the unit discrete coordinate system has axis 1 along the shell axis, axis 3 along the outer normal of the shell surface, and axis 2 orthogonal to axes 1 and 3. A 3×3 matrix T is defined to describe the discrete coordinate system. The unit discrete coordinate system of the grid unit is described according to the following formula:

[0087]

[0088] Wherein, T is the cell discrete coordinate system matrix, a1 is the direction cosines between the cell discrete coordinate axis 1 of the grid cell and the x-axis of the global coordinate system, b1 is the direction cosines between the cell discrete coordinate axis 1 of the grid cell and the y-axis of the global coordinate system, c1 is the direction cosines between the cell discrete coordinate axis 1 of the grid cell and the z-axis of the global coordinate system; a2 is the direction cosines between the cell discrete coordinate axis 2 of the grid cell and the x-axis of the global coordinate system, b2 is the direction cosines between the cell discrete coordinate axis 2 of the grid cell and the y-axis of the global coordinate system, c2 is the direction cosines between the cell discrete coordinate axis 2 of the grid cell and the z-axis of the global coordinate system; a3 is the direction cosines between the cell discrete coordinate axis 3 of the grid cell and the x-axis of the global coordinate system, b3 is the direction cosines between the cell discrete coordinate axis 3 of the grid cell and the y-axis of the global coordinate system, and c3 is the direction cosines between the cell discrete coordinate axis 3 of the grid cell and the z-axis of the global coordinate system.

[0089] The winding angle is the angle between the direction of the composite material's reinforcing fibers and axis 1 of the discrete coordinate system of the unit cell. The winding angle of the inner winding layer of the skirt is calculated using a non-geodesic mathematical model. The winding angle of each layer of the outer winding layer of the skirt is 0° or 90°. The specific calculation method is:

[0090] Establish the relationship between the parallel circle radius r of the shell head and the coordinate z of the axis of rotation, such as Figure 16As shown; then the first and second derivatives of r are calculated to obtain r' and r". Finally, the head slip coefficient λ is given, and the winding angle at the pole hole is set to 89.99° as the initial condition. Substituting r, r', and r", the ordinary differential equation is solved to obtain the winding angle at any point of the shell head. The unit fiber winding angle of any mesh unit located on the head section is described by the following formula:

[0091]

[0092] Where α represents the fiber winding angle of the unit cell, z represents the coordinate of the grid unit cell on the z-axis of the solid motor case coordinate system, d represents the differential sign, λ represents the head slip coefficient, r represents the parallel circle radius at the grid unit cell, r' represents the first derivative of r, and r" represents the second derivative of r.

[0093] In addition, the winding angle of the shell barrel section is a constant value, which is equal to the winding angle at the equatorial circle of the head (i.e., the junction of the head and the barrel section), while the winding angle of the outer winding layer of the shell skirt is initially given, and each layer is 90° or 0°.

[0094] Assume that the number of meshes divided in the shell circumference is N, then the angle θ swept by a single copy node is m It can be calculated according to the following formula:

[0095] θ m =360° / N.

[0096] Assuming the coordinates of the cross-section source grid scattered points are (x1, y1, z1), the specific process of unit generation is:

[0097] Before performing step A4, the method provided in this embodiment further includes the following steps:

[0098] Construct the eight-vertex mesh unit array element_1, the six-vertex mesh unit array element_2, the discrete coordinate coefficient array ori, and the fiber winding angle array alp. The eight-vertex mesh unit array element_1 is used to store C3D8R units. The format is shown in Table 3:

[0099] Table 3 Format of element_1 array

[0100] Node 1 Node 2 Node 3 Node 4 Node 5 Node 6 Node 7 Node 8 1 <![CDATA[A1]]> <![CDATA[B1]]> <![CDATA[C1]]> <![CDATA[D1]]> <![CDATA[E1]]> <![CDATA[F1]]> <![CDATA[G1]]> <![CDATA[H1]]> 2 <![CDATA[A2]]> <![CDATA[B2]]> <![CDATA[C2]]> <![CDATA[D2]]> <![CDATA[E2]]> <![CDATA[F2]]> <![CDATA[G2]]> <![CDATA[H2]]> ......

[0101] The six-vertex mesh unit array element_2 is used to store C3D6 units. The format is shown in Table 4:

[0102] Table 4 Format of element_2 array

[0103] Node 1 Node 2 Node 3 Node 4 Node 5 Node 6 1 <![CDATA[A1]]> <![CDATA[B1]]> <![CDATA[C1]]> <![CDATA[D1]]> <![CDATA[E1]]> <![CDATA[F1]]> 2 <![CDATA[A2]]> <![CDATA[B2]]> <![CDATA[C2]]> <![CDATA[D2]]> <![CDATA[E2]]> <![CDATA[F2]]> ......

[0104] The discrete coordinate coefficient group is used to store the discrete coordinate system matrix of each grid unit body. Its format is shown in Table 5:

[0105] Table 5 ori array format

[0106]

[0107] The fiber winding angle array is used to store the fiber winding angle of each grid cell. Its format is shown in Table 6:

[0108] Table 6 alp array format

[0109] Winding Angle 1 <![CDATA[A1]]> 2 <![CDATA[A2]]> ......

[0110] The number of each vertex of a finite element mesh unit body with eight vertices in the cross section of the solid engine casing is taken as a piece of data and stored in an eight-vertex mesh unit body array.

[0111] The number of each vertex of a finite element mesh unit body with six vertices in the cross section of the solid engine casing is taken as a piece of data and stored in a six-vertex mesh unit body array.

[0112] The discrete coordinate system matrix of each grid unit body in the finite element grid unit body of the solid rocket shell section is stored in the discrete coordinate coefficient group.

[0113] The fiber winding angle of each grid unit body in the finite element grid unit body of the solid engine shell section is stored in the fiber winding angle array.

[0114] A4. Based on the central axis of the solid motor case, repeatedly rotate the finite element mesh unit body of the solid motor case cross section by a preset angle until it coincides with the finite element mesh surface of the solid motor case cross section, thereby obtaining a finite element mesh model of the solid motor case; the finite element mesh model of the solid motor case is composed of multiple finite element mesh unit bodies of the solid motor case cross section. Step A4 specifically includes the following steps:

[0115] A41. Based on the central axis of the solid motor case, the finite element mesh unit body of the solid motor case cross section is rotated by a preset angle to obtain the latest finite element mesh unit body; the number of mesh units in the latest finite element mesh unit body is the same as the number of mesh units in the finite element mesh unit body of the solid motor case cross section.

[0116] Assume that the coordinates of a scattered point M1 on the finite element mesh unit of the cross section are (x1, y1, z1), copy the scattered point M1, and rotate it by angle θ = θ m , M2 is obtained using the formula for rotating point M1 around the x-axis by an angle θ.

[0117]

[0118] A42. Add the spatial positions of each discrete point in the latest finite element mesh to the solid rocket casing discrete point array. As described above, rotate M1 to obtain M2. Rotate each scattered point one by one, and store the number and coordinates of each new scattered point in the Node array.

[0119] A43. In the latest finite element mesh unit, the number of each vertex of the mesh unit with eight vertices is used as a data and added to the eight-vertex mesh unit array. From left to right, generate units layer by layer according to the unit number sequence. The main area uses the C3D8 unit number sequence. Figure 17 In the manner shown, new scattered points are generated, and the units composed of the generated scattered points are stored into the element_1 array one by one.

[0120] A44. Add the vertex number of each six-vertex mesh unit in the latest finite element mesh unit as a piece of data to the six-vertex mesh unit array. Generate units layer by layer from left to right according to the unit number sequence. The winding layer transition area uses the C3D6 unit number sequence. Figure 18 In the manner shown, new scattered points are generated, and the units composed of the generated scattered points are stored one by one into the element_2 array.

[0121] A45. Add the discrete coordinate system matrix of each mesh unit in the latest finite element mesh unit to the discrete coordinate coefficient group. Calculate the deflection angle β of each generated composite element with respect to the x-axis, calculate the angle γ between the center of each composite element and the XOY plane, and determine the initial discrete coordinate system T0. The expression of T0 satisfies the following formula:

[0122]

[0123] If the deflection angle β of a unit is 0, the discrete coordinate system T of the unit is N It can be calculated according to the vector rotation formula, namely:

[0124]

[0125] If the deflection angle β of a unit is 0, the discrete coordinate system T of the unit is Nf Need to be in T N Based on the rotation around the z axis by an angle β, that is:

[0126]

[0127] Store the generated discrete coordinate system matrices into the ori array one by one.

[0128] A46. Add the fiber winding angle of each mesh cell in the latest finite element mesh cell to the fiber winding angle array. Calculate the winding angle at the center of each generated composite element and store the winding angles sequentially in alp.

[0129] A47, determine whether it coincides with the finite element mesh surface of the solid engine shell section. If so, execute step A48: end the rotation to obtain the finite element mesh model of the solid engine shell; if not, jump to step A41: based on the central axis of the solid engine shell, rotate the finite element mesh unit body of the solid engine shell section by a preset angle to obtain the latest finite element mesh unit body. Finally, the result is as follows Figure 19 The finite element mesh model is shown.

[0130] This embodiment provides a method for generating a finite element mesh model of a solid motor casing. The method comprises the following steps: performing an axial compressive load analysis on the solid motor casing to construct a finite element mesh surface of the solid motor casing cross section; rotating the finite element mesh surface of the solid motor casing cross section by a preset angle based on the central axis of the solid motor casing to obtain a finite element mesh unit body of the solid motor casing cross section; defining a unit discrete coordinate system and a unit fiber winding angle for each mesh unit body; and repeatedly rotating the finite element mesh unit body of the solid motor casing cross section by a preset angle based on the central axis of the solid motor casing until the unit body coincides with the finite element mesh surface of the solid motor casing cross section to obtain a finite element mesh model of the solid motor casing. This embodiment comprehensively considers factors such as the initial geometric defects of the casing, the form of structural deformation, and the calculation accuracy. The structure of the solid motor casing subjected to axial compressive load is discretized layer by layer, and a rotation sweep is performed based on the cross-sectional finite element mesh surface to construct a finite element mesh model of a solid motor casing suitable for a load-bearing portion made of anisotropic material. This method facilitates the simulation and analysis of the mechanical behavior of three-dimensional entities under axial loading.

[0131] Example 2

[0132] In addition, the finite element mesh model generation method of a solid motor casing according to embodiment 1 of the present invention can also be achieved by Figure 20 The architecture of a finite element mesh model generation system for a solid engine casing is implemented as shown. Figure 20 As shown, the finite element mesh model generation system of the solid engine casing may include a finite element mesh surface construction module, a finite element mesh unit body construction module, a unit body discrete coordinate system determination module, a unit body fiber winding angle determination module and a finite element mesh model construction module; some modules may also have subunits for realizing their functions. Of course, Figure 20The architecture shown is only exemplary and can be omitted according to actual needs when implementing different functions. Figure 20 One or at least two components of the system shown.

[0133] Example 3

[0134] A computer device, which may be a database, may have an internal structure as shown in FIG. Figure 21 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, the memory and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store pending transactions. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, it implements a finite element mesh model generation method for a solid engine casing in Example 1.

[0135] It should be noted that the object information (including but not limited to object device information, object personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in the present invention are all information and data authorized by the object or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions.

[0136] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), data processing logic devices based on quantum computing, and the like.

[0137] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0138] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for generating a finite element mesh model of a solid motor casing, wherein the solid motor casing comprises a barrel section and two head sections located on both sides of the barrel section, wherein a polar hole is formed on the head section away from the center of the barrel section; characterized in that: include: Perform axial compression load analysis on the solid rocket shell and construct the finite element mesh surface of the solid rocket shell cross section; The finite element mesh surface of the cross section of the solid motor casing includes the finite element mesh surface of the inner winding layer of the skirt, the finite element mesh surface of the metal skirt, the finite element mesh surface of the rubber layer and the finite element mesh surface of the outer winding layer of the skirt; any of the finite element mesh surfaces is composed of a plurality of discrete points; Based on the central axis of the solid motor case, the finite element mesh surface of the solid motor case cross section is rotated by a preset angle to obtain a finite element mesh unit body of the solid motor case cross section; The finite element grid unit body of the solid motor case cross section includes a plurality of grid unit bodies; the central axis is a line connecting the polar holes on the two head segments; the preset angle is divisible by 360; For any grid unit body, defining a unit body discrete coordinate system and a unit body fiber winding angle of the grid unit body; Based on the central axis of the solid motor case, repeatedly rotating the finite element mesh unit body of the solid motor case cross section by a preset angle until it coincides with the finite element mesh surface of the solid motor case cross section, thereby obtaining a finite element mesh model of the solid motor case; The finite element grid model of the solid motor casing is composed of a plurality of finite element grid unit bodies of the solid motor casing cross sections.

2. The method for generating a finite element mesh model of a solid motor casing according to claim 1, characterized in that: Perform axial compression load analysis on the solid rocket motor case and construct a finite element mesh surface of the solid rocket motor case cross section, including: Obtain the thickness of a single-layer winding layer in the barrel section, and use the cubic spline formula method to calculate the thickness of a single-layer winding layer at any position in the head section; Based on the thickness of a single winding layer, discrete points of each contour line of the inner winding layer of the skirt are generated, and a finite element mesh surface of the inner winding layer of the skirt is constructed; Based on the finite element mesh surface of the inner winding layer of the skirt, discrete points of each contour line of the metal skirt are generated to construct the finite element mesh surface of the metal skirt; Based on the finite element mesh surface of the inner winding layer of the skirt and the finite element mesh surface of the metal skirt, discrete points of each contour line of the rubber layer are generated according to the thickness of each layer to construct the finite element mesh surface of the rubber layer; Based on the finite element mesh surface of the inner wrapping layer and the rubber layer, discrete points of each contour line of the outer wrapping layer are generated according to the thickness of the single wrapping layer to construct the finite element mesh surface of the outer wrapping layer. The finite element mesh surface of the solid rocket motor case cross section is constructed based on the finite element mesh surface of the inner winding layer of the skirt, the finite element mesh surface of the metal skirt, the finite element mesh surface of the rubber layer and the finite element mesh surface of the outer winding layer of the skirt.

3. The method for generating a finite element mesh model of a solid motor casing according to claim 2, characterized in that: The inner skirt wrapping layer has overlapping contour lines with the rubber layer and the outer skirt wrapping layer respectively; the rubber layer has overlapping contour lines with the metal skirt layer and the outer skirt wrapping layer respectively.

4. The method for generating a finite element mesh model of a solid motor casing according to claim 2, characterized in that: The thickness of a single-layer winding layer at any position of the head section can be calculated according to the following formula: Among them, r i is the radius of the parallel circle at any position of the head section; m1, m2, m3 and m4 are the undetermined coefficients of the cubic spline formula method; Determine the unknown coefficients m1, m2, m3 and m4 according to the following formula: Among them, r0 is the radius of the polar hole; b is the width of the fiber yarn; r b is the radius of the parallel circle at the position of one bandwidth; r 2b is the radius of the parallel circle at the position of twice the bandwidth; t R is the thickness of the winding layer of the barrel section; R is the radius of the barrel section; α0 is the diameter of the pole hole; m0 is the number of fiber yarns at the pole hole position; m R is the number of fiber yarn sheets in the barrel section; n R is the number of spiral winding layers of the barrel section; t p is the thickness of the single-layer winding layer of the barrel section; d is the differential symbol.

5. The method for generating a finite element mesh model of a solid motor casing according to claim 2, characterized in that: Before generating discrete points of each contour line of the inner skirt winding layer based on the thickness of the single winding layer and constructing the finite element mesh surface of the inner skirt winding layer, the following steps are also included: Construct the discrete point array of the solid motor shell, the discrete point array of the inner winding layer of the skirt, the discrete point array of the metal skirt, the discrete point array of the rubber layer and the discrete point array of the outer winding layer of the skirt; When generating discrete points of each contour line of the inner skirt winding layer, the spatial position of each discrete point is sequentially added to the solid motor casing discrete point array, and the number of each discrete point is stored in the inner skirt winding layer discrete point array according to the order of the contour line; the number of columns of the inner skirt winding layer discrete point array is the same as the number of discrete points on a single contour line of the inner skirt winding layer; the number of rows of the inner skirt winding layer discrete point array is the same as the number of contour lines of the inner skirt winding layer; When generating discrete points of each contour line of the metal skirt, the spatial position of each discrete point is sequentially added to the solid motor case discrete point array, and the number of each discrete point is stored in the metal skirt discrete point array according to the order of the contour line; the number of columns of the metal skirt discrete point array is the same as the number of discrete points on a single contour line of the metal skirt; and the number of rows of the metal skirt discrete point array is the same as the number of contour lines of the metal skirt; When generating discrete points for each contour line of the rubber layer, the spatial position of each discrete point is sequentially added to the solid motor case discrete point array, and the number of each discrete point is stored in the rubber layer discrete point array according to the order of the contour lines; the number of columns of the rubber layer discrete point array is the same as the number of discrete points on a single contour line of the rubber layer; and the number of rows of the rubber layer discrete point array is the same as the number of contour lines of the rubber layer; When generating discrete points of each contour line of the skirt outer winding layer, the spatial position of each discrete point is added to the solid engine casing discrete point array in sequence, and the number of each discrete point is stored in the skirt outer winding layer discrete point array according to the order of the contour line; the number of columns of the skirt outer winding layer discrete point array is the same as the number of discrete points on a single contour line of the skirt outer winding layer; the number of rows of the skirt outer winding layer discrete point array is the same as the number of contour lines of the skirt outer winding layer.

6. The method for generating a finite element mesh model of a solid motor casing according to claim 5, characterized in that: Before repeatedly rotating the finite element mesh unit body of the solid motor case cross section by a preset angle based on the central axis of the solid motor case, the method further includes: Constructing an eight-vertex mesh unit cell array, a six-vertex mesh unit cell array, a discrete coordinate coefficient group, and a fiber winding angle array; The numbers of the vertices of the eight-vertex mesh unit body in the finite element mesh unit body of the solid rocket shell section are stored as a piece of data in the eight-vertex mesh unit body array; The numbers of the vertices of the six-vertex grid unit body in the finite element grid unit body of the solid rocket shell section are stored as a piece of data in the six-vertex grid unit body array; storing the discrete coordinate system matrix of each grid unit body in the finite element grid unit body of the solid motor case cross section into the discrete coordinate coefficient group; The fiber winding angle of each grid unit body in the finite element grid unit body of the solid motor case cross section is stored in the fiber winding angle array.

7. The method for generating a finite element mesh model of a solid motor casing according to claim 6, characterized in that: Based on the central axis of the solid motor case, the finite element mesh unit body of the solid motor case cross section is repeatedly rotated by a preset angle until it coincides with the finite element mesh surface of the solid motor case cross section, thereby obtaining a finite element mesh model of the solid motor case, specifically including: Based on the central axis of the solid motor case, the finite element grid unit body of the solid motor case cross section is rotated by a preset angle to obtain an updated finite element grid unit body; the number of grid units in the updated finite element grid unit body is the same as the number of grid units in the finite element grid unit body of the solid motor case cross section; Adding the spatial position of each discrete point in the latest finite element grid unit volume to the solid motor casing discrete point array in sequence; Adding the number of each vertex of a mesh unit body with eight vertices in the latest finite element mesh unit body as a piece of data to the eight-vertex mesh unit body array; Adding the number of each vertex of a mesh unit body with six vertices in the latest finite element mesh unit body as a piece of data to the six-vertex mesh unit body array; Adding the discrete coordinate system matrix of each grid unit body in the latest finite element grid unit body to the discrete coordinate coefficient group; Adding the unit fiber winding angle of each grid unit in the latest finite element grid unit to the fiber winding angle array; Determine whether it coincides with the finite element mesh surface of the solid engine case cross section. If so, end the rotation to obtain the finite element mesh model of the solid engine case; if not, jump to step: based on the central axis of the solid engine case, rotate the finite element mesh unit body of the solid engine case cross section by a preset angle to obtain the latest finite element mesh unit body.

8. The method for generating a finite element mesh model of a solid motor casing according to claim 1, characterized in that: The cell discrete coordinate system of the grid cell is described by the following equation: Wherein, T is the cell discrete coordinate system matrix, a1 is the direction cosine between the axis 1 of the cell discrete coordinate system of the grid cell and the x-axis of the global coordinate system, b1 is the direction cosine between the axis 1 of the cell discrete coordinate system of the grid cell and the y-axis of the global coordinate system, c1 is the direction cosine between the axis 1 of the cell discrete coordinate system of the grid cell and the z-axis of the global coordinate system; a2 is the direction cosine between the axis 2 of the cell discrete coordinate system of the grid cell and the x-axis of the global coordinate system, b2 is the direction cosine between the axis 2 of the cell discrete coordinate system of the grid cell and the y-axis of the global coordinate system, c2 is the direction cosine between the axis 2 of the cell discrete coordinate system of the grid cell and the z-axis of the global coordinate system; a3 is the direction cosine between the axis 3 of the cell discrete coordinate system of the grid cell and the x-axis of the global coordinate system, b3 is the direction cosine between the axis 3 of the cell discrete coordinate system of the grid cell and the y-axis of the global coordinate system, and c3 is the direction cosine between the axis 3 of the cell discrete coordinate system of the grid cell and the z-axis of the global coordinate system.

9. The method for generating a finite element mesh model of a solid motor casing according to claim 1, characterized in that: The fiber winding angle of any mesh unit cell located on the head section is described by the following formula: Wherein, α represents the fiber winding angle of the unit cell, z represents the coordinate of the grid unit cell on the z-axis of the solid engine casing coordinate system, d represents the differential sign, λ represents the head slip coefficient, r represents the parallel circle radius at the grid unit cell, r' represents the first derivative of r, and r" represents the second derivative of r.

10. A finite element mesh model generation system for a solid engine casing, characterized in that: The finite element mesh model generation system for a solid motor casing is used to implement a finite element mesh model generation method for a solid motor casing according to any one of claims 1 to 9.

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