High-precision parametric modeling method for fiber winding shell

Abstract

The invention relates to the technical field of solid rocket engine shell modeling, in particular to a fiber winding shell high-precision parametric modeling method which comprises the steps that structural parameters and technological parameters of a winding shell are obtained; obtaining the total thickness of a winding layer of the end socket section of the shell and an outer contour curve of the shell; obtaining the upper edge lines of all the spiral winding layers; and obtaining a three-dimensional finite element model of the shell. According to the method, the design efficiency of a complex shell structure is improved, the solid rocket engine winding shell model can be accurately and rapidly established, and the problems that an existing winding shell is long in modeling time and inaccurate in structure are solved.

Description

Technical Field

[0001] The invention relates to the technical field of solid rocket engine casing modeling, and in particular to a high-precision parameterized modeling method for a filament-wound casing. Background Art

[0002] The solid rocket engine case is not only an important component of the rocket engine, but also a major component of the spacecraft structure. As the engine's propellant tank and combustion chamber, it must withstand high internal pressure loads during the engine's operation, and at the same time withstand and transmit various external loads of the spacecraft. The case characteristic coefficient PV / W (P, V, and W are the bursting pressure, structural volume, and mass of the case, respectively) is an important indicator that characterizes the design and production process level of the case, and places high demands on the comprehensive performance of the engine case. Composite materials have excellent properties such as high specific strength, high specific stiffness, strong corrosion resistance, and designable material properties. They have been widely used in the aerospace field. The use of fiber winding technology as the process molding technology for composite pressure vessels enables the case to meet the requirements of lightweight and high internal pressure, and has achieved large-scale and low-cost structure.

[0003] The fiber-wound composite shell has complex features such as anisotropy, variable thickness and variable angle of materials, which makes many mature design and calculation methods of metal pressure vessels inapplicable. At present, the main shell design methods are grid theory, film theory and finite element method, but each method has its limitations, and the process of accurately analyzing the mechanical properties of the shell is relatively complicated. Zhang Qian and others invented a solid rocket engine shell modeling method and system. Based on the outer contour of the core model in ABAQUS, the coordinates of the starting point of the thickness growth of each winding layer are calculated in turn, and the shell contour curve is obtained by B-spline curve fitting, so as to quickly construct a solid rocket engine shell model. However, complex structural features such as the skirt connection area are not considered. When the rocket body is subjected to complex aerodynamic effects, the shell will be subjected to complex loads of pressure and bending moment through the skirt connection area, which cannot be ignored in structural analysis.

[0004] The wound shell structure is relatively complex, especially the variable angle and thickness distribution of the winding layer and the addition of reinforcement layer at the shell head. The manual modeling process in the commercial finite element software ABAQUS is very complicated and tedious. The structural parameters need to be constantly modified during the structural optimization process, which will consume a lot of time.

[0005] Therefore, it is necessary to provide a high-precision parametric modeling method for a fiber-wound shell to solve the above problems. Summary of the invention

[0006] The present invention provides a high-precision parametric modeling method for a filament-wound shell, which efficiently connects the shell design and analysis processes based on Python scripts, and quickly evaluates the shell bearing performance during the design, thereby shortening the design cycle to solve existing problems.

[0007] A high-precision parametric modeling method for a filament-wound shell of the present invention adopts the following technical scheme, including: Obtain the structural parameters and process parameters of the winding shell; wherein the structural parameters include: the radius of the barrel section, the length of the barrel section, the length of the major semi-axis of the inner contour ellipse of the head, the length of the minor semi-axis of the inner contour ellipse of the head, the radius of the large pole hole and the radius of the small pole hole; the process parameters include: winding layer, sliding line coefficient, barrel spiral winding angle, number of cyclic windings, yarn thickness and yarn width; The total thickness of the winding layer of the barrel section is obtained according to the winding layer, and the total thickness of the winding layer of the head section of the shell is calculated according to the structural parameters and process parameters and the cubic spline thickness prediction formula; According to the total thickness of the winding layer of the head section and the total thickness of the winding layer of the barrel section, the outer contour curve of the shell is drawn in sections using a spline curve; Define the upper surface meridian of each spiral winding layer section as the upper edge line, the upper edge line of the core mold head section is the lower surface meridian of the spiral winding layer section, obtain the angle between the tangent at different positions on the core mold head section contour curve and the shell axial direction, and obtain the first coordinate change from the upper edge line of the core mold head section contour curve to the corresponding point of the upper edge line of the first spiral winding layer according to the angle and the total thickness of the winding layer of the head section; According to the first coordinate variation and the coordinates of the discrete points of the contour curve of the core mold head section, the position coordinates of the upper edge line of the first spiral winding layer and each discrete point of the upper edge line are obtained; based on the angles between the tangent at different positions on the upper edge line of the first spiral winding layer and the axial direction of the shell, and the total thickness of the winding layer of the head section, the second coordinate variation from the upper edge line of the first spiral winding layer to the upper edge line of the second spiral winding layer is obtained; based on the second coordinate variation and the position coordinates of each point on the upper edge line of the first spiral winding layer, the position coordinates of the upper edge line of the second spiral winding layer and each point on the upper edge line are obtained, and so on, the upper edges of all spiral winding layers are obtained; According to the outer contour curve of the shell, a triangular resin-rich area is drawn between every two spiral winding layers on the equatorial circle at the connection between the barrel section and the head section, and a two-dimensional modeling curve diagram of the shell half section is obtained; Based on the two-dimensional modeling curve graph of the shell half section, a three-dimensional finite element model is obtained.

[0008] Preferably, the step of obtaining the angle between the tangent at different positions on the contour curve of the core mold head section and the axial direction of the shell is: Formulate discrete partitioning principles, determine the partitions of the head section and barrel section corresponding to the core mold, and obtain the position coordinates of the corresponding discrete points in each partition on the core mold; Obtain the tangent slope of the discrete point on the contour curve of the mandrel head section according to the position coordinates of the discrete point on the contour curve of the mandrel head section and the major semi-axis and minor semi-axis of the cross-sectional area of ​​the mandrel head section at the discrete point; According to the tangent slope of the discrete point on the contour curve of the core mold head section, the angle between the tangent of the discrete point on the contour curve of the core mold head section and the axial direction of the shell is obtained.

[0009] Preferably, the angle between the tangent of the discrete points on the contour curve of the core mold head section and the axial direction of the shell is expressed as:

[0010] In the formula, It represents the angle between the tangent line at the discrete point (x, y) on the contour curve of the core mold head section and the axial direction of the shell; It represents the slope of the tangent line at the discrete point (x, y) on the contour curve of the core mold head section; Represents the major semi-axis of the contour curve of the core mold head section; Represents the short semi-axis of the contour curve of the core mold head section.

[0011] Preferably, the position coordinates of discrete points on the outer contour curve of the core mold are obtained according to the core mold reference curve equation.

[0012] Preferably, the expression of the relative coordinate change from the upper edge of the core mold end section to the corresponding point of the upper edge of the first winding layer is:

[0013] In the formula, Indicates the first horizontal coordinate change from the upper edge of the core mold end section to the corresponding point of the upper edge of the first winding layer; Indicates the change in the first ordinate from the upper edge of the core mold end section to the corresponding point of the upper edge of the first winding layer; Indicates the thickness of a single winding layer of the head section; It represents the angle between the tangent line at the discrete point (x, y) on the contour curve of the core mold head section and the axial direction of the shell.

[0014] Preferably, the steps of obtaining the three-dimensional finite element model are: The starting position of the head of any winding layer in the two-dimensional modeling curve diagram of the half-section of the shell is retracted to obtain a two-dimensional modeling curve diagram after retraction, and the retraction length is less than twice the width of the winding tape; Obtain the reinforcement layer in the winding layer corresponding to the two-dimensional modeling curve diagram after the retreat; Reinforcing the reinforcement layer in the two-dimensional modeling curve diagram of the half-section of the shell to obtain a target two-dimensional modeling curve diagram; Based on the target two-dimensional modeling curve, a three-dimensional finite element model of the shell is generated by rotating around the center of the core mold.

[0015] Preferably, the step of obtaining the reinforcement layer is: Obtaining the remainder after comparing the layer number of the winding layer in the three-dimensional finite element model with a preset value; According to the remainder, it is determined whether the winding layer corresponding to the layer number is a reinforcement layer.

[0016] Preferably, the three-dimensional finite element models of the metal joint and the shell are combined and modeled, wherein the metal joint and the shell are bonded with a rubber layer.

[0017] Preferably, the method further comprises: constructing a finite element model of the skirt shell, the construction steps being: Draw the outer contour of the meridian section of the metal skirt according to the characteristic parameters of the metal skirt; The outer contour image is used as the initial feature surface and rotated into a metal skirt model; Add material properties to the metal skirt model and perform meshing to obtain a finite element model of the metal skirt; The connection area of ​​the finite element model of the shell and the finite element model of the metal skirt is assembled, and the load and boundary conditions are applied as required to add binding interactions to obtain the finite element model of the shell including the skirt.

[0018] The beneficial effects of the present invention are: Based on Python language, a scripted model that can be run in finite element software is established to realize Abaqus secondary development. By modifying the input parameters, the shell model can be automatically generated by running the script, that is, the parametric design of the wound shell is realized, which significantly improves the design efficiency of complex shell structures and can accurately and quickly establish the wound shell model of the solid rocket engine, solving the current problems of long modeling time and inaccurate structure of the wound shell. Based on this parametric script, multiple iterative designs can be performed to optimize the performance of the shell model, which is of great significance to the design of composite pressure vessels. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0020] Figure 1 A flowchart of a high-precision parameterized modeling method for a filament-wound shell according to the present invention; Figure 2 It is a schematic diagram of the fiber winding at the shell head; Figure 3 is a schematic diagram of the thickness profile curve of the shell; Figure 4 It is a schematic diagram of the resin-rich area at the equatorial circle; Figure 5 A schematic diagram of the pole hole formed by the winding layer after retreat; Figure 6 Schematic diagram of the reinforcement layer and the spiral winding layer; Figure 7 It is a schematic diagram of the connection between the shell, the metal joint and the plug cover; Figure 8 It is a schematic diagram of the curve of the winding angle on the head section changing with the axial position under different sliding line coefficients; Fig. 9 is a schematic diagram of the shell loading condition; Fig.10 It is a schematic diagram of the characteristic structure of the skirt connection area; Fig.11 Schematic diagram of the finite element model of the skirt shell. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0022] An embodiment of a high-precision parametric modeling method for a fiber-wound shell of the present invention is described. In this embodiment, a composite material wound shell model with a reduced diameter of φ480 mm is used as an example. Figure 1 As shown, this embodiment specifically includes: S1. Obtaining structural parameters and process parameters of the winding shell; The structural parameters in the embodiment include: barrel section radius 237mm, barrel section length 270mm, head inner contour ellipse major semi-axis length 237mm, head inner contour ellipse minor semi-axis length 118.5mm, large pole hole radius 120mm, small pole hole radius 86mm; process parameters include: winding number 9 layers (i.e. 3 spiral winding layers and 6 annular winding layers), sliding line coefficient 0.1, barrel spiral winding angle 28°, cyclic winding number 182, yarn thickness 0.225mm and yarn width 7.5mm.

[0023] S2, obtaining the total thickness of the winding layer of the head section of the shell and the outer contour curve of the shell; Specifically, the total thickness of the winding layer of the barrel section is obtained according to the winding layer, and the total thickness of the winding layer of the head section of the shell is calculated according to the structural parameters and process parameters and the cubic spline thickness prediction formula; according to the total thickness of the winding layer of the head section and the total thickness of the winding layer of the barrel section, the outer contour curve of the shell is drawn in segments using a spline curve.

[0024] Step 21, the step of obtaining the total thickness of the winding layer of the barrel section according to the winding layer is: In this embodiment, the total thickness of the winding layers of the barrel section is 2.7 mm according to the winding layers, that is, the number of winding layers is 3 spiral winding layers and 6 circumferential winding layers, wherein the ply angles of the spiral winding layers are counted as one layer (the thickness of a spiral winding layer is actually twice the thickness of the yarn tape), and the total thickness of the winding layers of the barrel section is 12 times the thickness of the yarn tape, that is, 2.7 mm.

[0025] Step 22: Calculate the total thickness of the winding layer of the head section of the shell according to the structural parameters and process parameters and using the cubic spline thickness prediction formula: When the fiber is wound around the shell head, the geometric relationship between the head and the yarn is as follows: Figure 2 As shown, assuming that the yarn is in this Figure 2 The straight line is shown below. According to the geometric relationship, in the area within the width of a yarn tape at the end of the end cap, the total thickness of the winding layer at point A is equal to the sum of the thickness of the yarn tape passing through BC during the winding process, that is, the total thickness formula of the winding layer within the width of a yarn tape at the end cap:

[0026] In the formula, is the number of cycle windings; is the number of spiral winding layers; is the thickness of the yarn; is the width of the yarn tape; is the pole hole radius, and r represents the radial coordinate of the winding layer of the shell head section.

[0027] In the area outside the end hole of the head plus twice the width of the yarn tape, the total thickness of the winding layer at point A is:

[0028] In the formula, is the equatorial radius; Based on the formula for the total thickness of the winding layer within the polar hole of one yarn tape width, a cubic spline curve is used for fitting. The total thickness of the winding layer at the edge of the polar hole within the polar hole radius plus twice the yarn tape width is:

[0029] In the formula, the four constants A, B, C and D are unknown and need to be solved by four constraint equations. According to the actual boundary conditions of the structural geometry, we can obtain: ① the total thickness of the winding layer at the edge of the pole hole; ② the total thickness of the winding layer at the two tape widths; ③ the first-order derivative of the thickness at the two tape widths is continuous; ④ the total amount of fiber bundles within the two tape widths is consistent. Solving the four constraint conditions ①, ②, ③, and ④, we can get the total amount of fiber bundles within the two tape widths as follows:

[0030] In the formula, Indicates the total amount of fiber bundles within two tape widths; Indicates the number of loop windings; Indicates the number of layers of the spiral winding; represents the polar aperture radius; Indicates the thickness of the yarn tape; It means the radius of the pole hole plus twice the width of the ribbon; It represents the pole hole radius plus the width of the yarn tape; Represents the radial coordinate of the winding layer of the shell head section.

[0031] Finally, the total thickness of the winding layer in the area within the radius of the large end hole plus twice the width of the yarn tape is:

[0032] The total thickness of the winding layer in the area within the small end hole radius plus twice the width of the yarn tape is:

[0033] The total thickness of the winding layer in the area outside the pole hole radius plus twice the width of the yarn tape is:

[0034] Step 23: The steps for drawing the outer contour curve of the shell are: Since the lower surface of the first winding layer is the outer contour of the core mold model, the outer contour coordinates of the core mold model can be obtained by the core mold reference curve equation Then, based on the total thickness of the winding layer of the head section and the total thickness of the winding layer of the barrel section obtained in step 22, the outer contour curve of the shell is drawn in sections using a spline curve, such as Figure 3 As shown, the red line represents the outer contour curve of the shell, and the black line represents the inner contour curve of the shell (i.e., the outer contour curve of the core mold).

[0035] S3, obtaining the upper edges of all spirally wound layers; Since the calculation of the contour curve of the head section of the shell is an important link for multi-layer fiber-wound composite shells, the accurate generation of this data will directly affect the accuracy of the shell finite element model, and a certain point of the outer contour line of each spiral winding layer is obtained by offsetting a certain thickness value along the outer normal direction of the core mold at the corresponding point of the inner layer contour. The thickness direction of the shell head is the normal direction of the head curve, which cannot be directly used to calculate the coordinates of each winding layer of the shell. Therefore, it is necessary to calculate the change in thickness in the direction of the coordinate axis based on the relationship between the contour curve of the core mold head section and the coordinate axis. Therefore, the upper surface meridian of each spiral winding layer section is defined as the upper edge line, and the upper edge line of the core mold head section is the lower surface meridian of the spiral winding layer section.

[0036] Step 31, the steps of obtaining the angles between the tangents at different positions on the contour curve of the core mold head section and the axial direction of the shell are: Step 311, formulate discrete partitioning principles, determine the partitions of the head section and the barrel section corresponding to the core mold, and obtain the position coordinates of the corresponding discrete points in each partition on the core mold.

[0037] In this embodiment, since the thickness of each winding layer is considered when modeling layer by layer, the ply information of each winding layer is stored in three lists (0, 1, 2), corresponding to the left head section, the barrel section, and the right head section, respectively, and each list is defined as a tuple. Among them, the discrete partition principle is: set different discrete point steps in the head section and the barrel section of the shell (the left head section and the right head section are the same), and determine the number of partitions with the discrete point as the center. In this embodiment, the head section of the shell is divided into 90 intervals and the barrel section is divided into 6 intervals. The axial and radial directions of the head section and the barrel section are discretized to ensure that areas with different curvatures can be processed in detail.

[0038] Step 312, according to the position coordinates of the discrete points on the core mold head section contour curve, and the major and minor semi-axes of the cross-sectional area of ​​the core mold head section at the discrete points, obtain the tangent slope of the discrete points on the core mold head section contour curve, that is: The equation of the core mold head section contour curve is derived to obtain the tangent slope at different positions on the core mold head section contour curve, that is, the tangent slope is:

[0039] In the formula, It represents the slope of the tangent line at the discrete point (x, y) on the contour curve of the core mold head section; (x, y) represents the discrete point on the contour curve of the core mold head section; Represents the major semi-axis of the cross-sectional area at the discrete point (x, y) on the contour curve of the core mold head section; Represents the minor semi-axis of the cross-sectional area at the discrete point (x, y) on the contour curve of the core mold head section.

[0040] Step 313, according to the tangent slope of the discrete point on the core mold head section contour curve, obtain the angle between the tangent of the discrete point on the core mold head section contour curve and the shell axial direction, that is, the expression is:

[0041] In the formula, It represents the angle between the tangent line at the discrete point (x, y) on the contour curve of the core mold head section and the axial direction of the shell; It represents the slope of the tangent line at the discrete point (x, y) on the contour curve of the core mold head section; Represents the major semi-axis of the contour curve of the core mold head section; Represents the short semi-axis of the contour curve of the core mold head section.

[0042] Step 32, the step of obtaining the first coordinate change amount from the upper edge line of the core mold head section contour curve to the corresponding point of the upper edge line of the first spiral winding layer is:

[0043] In the formula, Indicates the change in the horizontal coordinate from the upper edge of the core mold end section to the corresponding point of the upper edge of the first winding layer; Indicates the change in the ordinate from the upper edge of the core mold end section to the corresponding point of the upper edge of the first winding layer; Indicates the thickness of a single winding layer of the head section; It represents the angle between the tangent line at the discrete point (x, y) on the contour curve of the core mold head section and the axial direction of the shell.

[0044] Among them, in the barrel section That is, only the y direction (i.e. the radial direction of the barrel) of the corresponding point of the upper edge line of the first spiral winding layer in the barrel section has a change, and the change of the upper edge line of the first spiral winding layer in the barrel section can be obtained.

[0045] Step 34, according to the first coordinate change and the discrete point coordinates of the contour curve of the core mold head section, obtain the position coordinates of the upper edge line of the first spiral winding layer and each discrete point of the upper edge line, based on the angle between the tangent at different positions on the upper edge line of the first spiral winding layer and the axial direction of the shell, and the total thickness of the winding layer of the head section, obtain the second coordinate change from the upper edge line of the first spiral winding layer to the upper edge line of the second spiral winding layer; based on the second coordinate change and the position coordinates of each point on the upper edge line of the first spiral winding layer, obtain the position coordinates of the upper edge line of the second spiral winding layer and each point on the upper edge line, and so on, obtain the upper edges of all spiral winding layers, wherein the position coordinates of each discrete point of the upper edge line of the first spiral winding layer corresponding to the barrel section can be obtained based on the discrete point coordinates of the contour curve of the core mold barrel section and the change of the barrel section, and so on, calculate each discrete point coordinate information of the upper edge line of the spiral winding layer layer by layer from bottom to top, and obtain the upper edges of all spiral winding layers of the shell.

[0046] S4, obtaining a three-dimensional finite element model of the shell; Specifically, according to the outer contour curve of the shell, a triangular resin-rich area is drawn between every two spiral winding layers on the equatorial circle at the connection between the barrel section and the head section, and a two-dimensional modeling curve graph of the shell half section is obtained; based on the two-dimensional modeling curve graph of the shell half section, a three-dimensional finite element model of the shell is obtained.

[0047] Step 41, the steps of drawing a triangular resin-rich area between every two spiral winding layers on the equatorial circle at the connection between the barrel section and the head section are: Since the fiber winding process is carried out in a manner that the spiral winding layer and the circumferential winding layer are spaced apart from each other, the circumferential winding layer ends at the equatorial circle of the head, and a sudden change in thickness occurs at a local position. Therefore, when calculating the position of the circumferential winding layer, special processing is required at the equatorial circle. A triangular resin-rich area is added between every two winding layers on the equatorial circle at the connection between the barrel section and the head section. At this time, the coordinate points of the head area are not updated, and then the upper edge line of the next spiral winding layer is drawn, thereby realizing the continuous change of the winding layer and obtaining the following Figure 4 The two-dimensional modeling curve diagram of the shell half section is shown. Step 42: Based on the two-dimensional modeling curve diagram of the half-section of the shell, the steps of obtaining the three-dimensional finite element model of the shell are as follows: Step 421, the starting position of the head of any layer of the winding layer in the two-dimensional modeling curve diagram of the half-section of the shell is retreated to obtain the two-dimensional modeling curve diagram after retreat, and the retreat length is less than twice the width of the winding tape. That is, due to the consideration of the hole expansion process in the three-dimensional finite element model, the thickness of the fiber winding layer within twice the bandwidth of the head opening edge is smoothed. Different thickness distributions are achieved by setting the starting position of the thickness of any winding layer, and the retreat length is less than twice the width of the tape, such as Figure 5As shown, the shell structure of the pole hole area after the pole hole is wound to simulate the retreat. After the pole hole of the winding layer retreats, the pole hole radius of this layer increases, and the angle and thickness distribution of the winding layer are recalculated based on the non-geodesic linear design method and the cubic spline method.

[0048] Step 422, the step of obtaining the reinforcement layer in the winding layer corresponding to the two-dimensional modeling curve diagram after the retreat is: In order to give full play to the performance of the composite material, the shell head can be reinforced to improve the head bearing capacity and the shell characteristic coefficient, that is, the three-dimensional finite element model is reinforced. The reinforcement steps are: obtain the remainder after the layer number K of the winding layer in the three-dimensional finite element model is compared with the preset value. In this embodiment, the preset value is set to 3. When the remainder after the comparison of K / 3 is 3 or 4, the winding layer corresponding to the layer number is the reinforcement layer; Figure 6 As shown, the reinforcement thickness and reinforcement angle of the reinforcement layer are set to reinforce the reinforcement layer. The laying angle is calculated according to relevant theories, and then the reinforcement area partition is identified, the corresponding reinforcement thickness and reinforcement angle are set, and the distribution of the reinforcement material is accurately restored. It should be noted that the reinforcement layer is equivalent to adding a spiral layer between the two spiral winding layers at the head position.

[0049] When the remainder of K / 5 is 0, 1 or 2, the winding layers corresponding to the layer numbers are hoop winding layers and spiral winding layers, and the laying angles are 90°, and ( is the winding angle).

[0050] Step 423, reinforcing the reinforcement layer in the two-dimensional modeling curve diagram of the half-section of the shell to obtain a target two-dimensional modeling curve diagram; based on the target two-dimensional modeling curve diagram, rotating around the center of the core mold to generate a three-dimensional finite element model of the shell.

[0051] Step 4231. Since the geometric structure of the wound shell changes periodically along the circumferential direction, for this type of structure, by performing two-dimensional modeling of the shell half-section and then applying cyclic symmetry constraints on the circumferential boundary, the calculation amount of the three-dimensional finite element model can be greatly reduced while ensuring the analysis accuracy.

[0052] Step 4232, use engineering constants to define the composite modulus of the three-dimensional finite element model, implement direct stiffness reduction through user-defined field variables FIELD, and use user subroutine USDFLD to determine the onset of damage and control damage evolution. When the stress state of the material point meets the corresponding failure criterion, the value of the field variable changes from 0 to 1, reflecting the state of the damage variable. If damage occurs, the reduced material parameters are used for calculation, and then the load is increased until the calculation is completed or does not converge. The material parameters are shown in Table 1.

[0053] Table 1

[0054] Among them, the material is assigned to the three-dimensional finite element model: each partition of each winding layer in the three-dimensional finite element model is assigned a material direction according to its axial position. A spiral winding layer is composed of two positive and negative winding layers, which are alternately wound with the hoop winding layer. The layer of the winding shell has Based on the non-geodesic winding line design theory, the winding angle at different positions of the shell is calculated. The principle formula is as follows: The winding angle differential equation is:

[0055] In the formula, is the sliding line coefficient, is the winding angle, Indicates the radial coordinate of the winding layer of the shell head section, corresponding to and The first and second derivatives of the radial coordinates of the winding layer are respectively calculated. The winding angle is determined by the geometric shape of the head surface and the sliding line coefficient, and the fourth-order Runge-Kutta method is used to solve it, such as Figure 8 As shown in the figure, under different sliding line coefficients, the winding angle distribution of the shell head has greater variation and design space.

[0056] Step 4233, set material properties, create material properties for the resin-rich area, metal skirt, metal joint, and rubber layer, all of which are isotropic materials, and assign them to the corresponding areas; Step 4234, meshing. In this embodiment, eight-node linear hexahedral elements (C3D8R) are used in the shell winding layer area, and the hourglass control option is enhanced. Wedge elements (C3D6) are used in the resin-rich area. C3D8R is also used for the metal joint, metal skirt, and rubber layer element types.

[0057] Step 4235, interaction settings: According to step 4231, apply cyclic symmetry constraints on the annular boundary, and the total number of sectors is 360° / sector angle; apply binding constraints on the inner surface of the two metal joints and the corresponding rubber layer, and on the lower surface of the shell and the corresponding rubber layer; set the analysis step type to static general, turn on large geometric deformation, and specify a dissipated energy fraction of 0.02%. The load type is inside pressure, and the first step of the analysis step applies a pressure of 17MPa to the shell structure. After reaching a stable state, the pressure is gradually increased to 22MPa in the second step. Reduce the maximum incremental step size to facilitate observation of the failure state. Fig. 9 As shown, the constraint method is to fix the upper end face of the joint and constrain the degrees of freedom other than the longitudinal displacement of the lower end face of the joint.

[0058] Step 4236, as Figure 7As shown, when the shell is working, the entire internal surface is subjected to internal pressure load, and the metal joints arranged at both ends of the shell are connected to the plugging covers to ensure the sealing of the container. Therefore, they cannot be ignored in the analysis. Therefore, the metal joints and the plugging covers are combined in the three-dimensional finite element model of the shell, and a rubber layer is used to bond the metal joints to the shell.

[0059] In addition, the shell is usually connected to the arrow body structure through a metal skirt and a flange. The present invention constructs a finite element model of the shell including the skirt according to the flange structure parameters, skirt parameters, rubber layer parameters and winding layer parameters. The specific steps are as follows: Step 1: Draw the outer contour of the meridian section of the metal skirt according to the characteristic parameters of the metal skirt. Fig.10 The metal skirt structure and characteristic parameters of the metal skirt are shown in Table 2.

[0060] Table 2

[0061] Since the outer winding reinforcement layer of the metal skirt has a step change in thickness direction at the end of the metal skirt, there will be problems such as discontinuous ply and excessive fiber turning angle. Therefore, a triangular area is designed at the end of the rubber layer to balance the thickness mutation generated by the metal skirt and the rubber. The outer winding reinforcement layer of the metal skirt is a spiral winding layer added outside the outer contour curve of the meridian section of the metal skirt based on the geometric relationship. The rubber layer is Fig.10 Medium purple area.

[0062] Step 2: Use the outer contour image as the initial feature surface and rotate it into a metal skirt model.

[0063] Step 3: Add material properties to the metal skirt model and perform meshing to obtain the finite element model of the metal skirt: The steps to add material properties are as follows: draw a split sketch of the metal skirt model, partition the metal skirt model by rotation splitting, so that the subsequent blocks can be assigned material properties. Referring to the characteristic parameters of the metal skirt, the metal skirt, rubber transition layer, skirt external axial winding reinforcement layer and circumferential winding reinforcement layer are split, and then material properties are added to the metal skirt model. Referring to the reduction method of material properties under different damage failure modes, the variables of each partition of the metal skirt model are read according to its geometric reference pattern coordinate position, the material properties are set, and the material direction of the fiber layer is set in a discrete manner.

[0064] Then, meshing is performed to obtain the finite element model of the metal skirt.

[0065] Step 4: Assemble the connection area between the shell finite element model and the metal skirt finite element model, apply loads and boundary conditions as required, add binding interactions, and obtain the finite element model of the shell with skirt. The finite element model of the shell with skirt is as follows: Fig.11 shown.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-precision parametric modeling method for a filament-wound shell, characterized in that: include: Obtain the structural parameters and process parameters of the winding shell; wherein the structural parameters include: the radius of the barrel section, the length of the barrel section, the length of the major semi-axis of the inner contour ellipse of the head, the length of the minor semi-axis of the inner contour ellipse of the head, the radius of the large pole hole and the radius of the small pole hole; the process parameters include: winding layer, sliding line coefficient, barrel spiral winding angle, number of cyclic windings, yarn thickness and yarn width; The total thickness of the winding layer of the barrel section is obtained according to the winding layer, and the total thickness of the winding layer of the head section of the shell is calculated according to the structural parameters and process parameters and the cubic spline thickness prediction formula; According to the total thickness of the winding layer of the head section and the total thickness of the winding layer of the barrel section, the outer contour curve of the shell is drawn in sections using a spline curve; Define the upper surface meridian of each spiral winding layer section as the upper edge line, the upper edge line of the core mold head section is the lower surface meridian of the spiral winding layer section, obtain the angle between the tangent at different positions on the core mold head section contour curve and the shell axial direction, and obtain the first coordinate change from the upper edge line of the core mold head section contour curve to the corresponding point of the upper edge line of the first spiral winding layer according to the angle and the total thickness of the winding layer of the head section; According to the first coordinate variation and the coordinates of the discrete points of the contour curve of the core mold head section, the position coordinates of the upper edge line of the first spiral winding layer and each discrete point of the upper edge line are obtained; based on the angles between the tangent at different positions on the upper edge line of the first spiral winding layer and the axial direction of the shell, and the total thickness of the winding layer of the head section, the second coordinate variation from the upper edge line of the first spiral winding layer to the upper edge line of the second spiral winding layer is obtained; based on the second coordinate variation and the position coordinates of each point on the upper edge line of the first spiral winding layer, the position coordinates of the upper edge line of the second spiral winding layer and each point on the upper edge line are obtained, and so on, the upper edges of all spiral winding layers are obtained; According to the outer contour curve of the shell, a triangular resin-rich area is drawn between every two spiral winding layers on the equatorial circle at the connection between the barrel section and the head section, and a two-dimensional modeling curve diagram of the shell half section is obtained; Based on the two-dimensional modeling curve graph of the shell half section, a three-dimensional finite element model is obtained.

2. A high-precision parametric modeling method for a filament-wound shell according to claim 1, characterized in that: The steps for obtaining the angle between the tangent line at different positions on the contour curve of the core mold head section and the axial direction of the shell are as follows: Formulate discrete partitioning principles, determine the partitions of the head section and barrel section corresponding to the core mold, and obtain the position coordinates of the corresponding discrete points in each partition on the core mold; Obtain the tangent slope of the discrete point on the contour curve of the mandrel head section according to the position coordinates of the discrete point on the contour curve of the mandrel head section and the major semi-axis and minor semi-axis of the cross-sectional area of ​​the mandrel head section at the discrete point; According to the tangent slope of the discrete point on the contour curve of the core mold head section, the angle between the tangent of the discrete point on the contour curve of the core mold head section and the axial direction of the shell is obtained.

3. A high-precision parametric modeling method for a filament-wound shell according to claim 2, characterized in that: The expression of the angle between the tangent line of the discrete points on the contour curve of the core mold head section and the axial direction of the shell is: In the formula, It represents the angle between the tangent line at the discrete point (x, y) on the contour curve of the core mold head section and the axial direction of the shell; It represents the slope of the tangent line at the discrete point (x, y) on the contour curve of the core mold head section; Indicates the major semi-axis of the contour curve of the core mold head section; Represents the short semi-axis of the contour curve of the core mold head section.

4. A high-precision parametric modeling method for a filament-wound shell according to claim 2, characterized in that: The position coordinates of discrete points on the outer contour curve of the core mold are obtained according to the core mold reference curve equation.

5. The high-precision parametric modeling method for a filament-wound shell according to claim 1, characterized in that: The expression of the first coordinate change from the upper edge of the core mold end section to the corresponding point of the upper edge of the first winding layer is: In the formula, Indicates the first horizontal coordinate change from the upper edge of the core mold end section to the corresponding point of the upper edge of the first winding layer; Indicates the change in the first ordinate from the upper edge of the core mold end section to the corresponding point of the upper edge of the first winding layer; Indicates the thickness of a single winding layer of the head section; It represents the angle between the tangent line at the discrete point (x, y) on the contour curve of the core mold head section and the axial direction of the shell.

6. A high-precision parametric modeling method for a filament-wound shell according to claim 1, characterized in that: The steps to obtain a three-dimensional finite element model are: The starting position of the head of any winding layer in the two-dimensional modeling curve diagram of the half-section of the shell is retracted to obtain a two-dimensional modeling curve diagram after retraction, and the retraction length is less than twice the width of the winding tape; Obtain the reinforcement layer in the winding layer corresponding to the two-dimensional modeling curve diagram after the retreat; Reinforcing the reinforcement layer in the two-dimensional modeling curve diagram of the half-section of the shell to obtain a target two-dimensional modeling curve diagram; Based on the target two-dimensional modeling curve graph, a three-dimensional finite element model of the shell is generated by rotating around the center of the core mold.

7. A high-precision parametric modeling method for a filament-wound shell according to claim 6, characterized in that: The steps to obtain the reinforcement layer are: Obtaining the remainder after comparing the layer number of the winding layer in the three-dimensional finite element model with a preset value; According to the remainder, it is determined whether the winding layer corresponding to the layer number is a reinforcement layer.

8. The high-precision parametric modeling method for a filament-wound shell according to claim 1, characterized in that: The three-dimensional finite element models of the metal joint and the shell are combined and modeled, wherein the metal joint and the shell are bonded with a rubber layer.

9. The high-precision parametric modeling method for a filament-wound shell according to claim 1, characterized in that: Also includes: The construction steps of the finite element model of the skirt shell are as follows: Draw the outer contour of the meridian section of the metal skirt according to the characteristic parameters of the metal skirt; The outer contour image is used as the initial feature surface and rotated into a metal skirt model; Add material properties to the metal skirt model and perform meshing to obtain a finite element model of the metal skirt; The connection area of ​​the finite element model of the shell and the finite element model of the metal skirt is assembled, and the load and boundary conditions are applied as required to add binding interactions to obtain the finite element model of the shell including the skirt.

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