A method for corner control of interlaminar toughening lines in a composite preform process

Abstract

This invention discloses a method for controlling the rotation angle of interlaminar toughening lines in the preforming process of composite materials, relating to the field of composite material molding technology. It addresses the technical problem that in existing composite materials, during the implantation of interlaminar toughening fibers, slippage between fibers causes deviations in the rotation angle of the toughening fibers from the designed angle, resulting in a molded body that fails to meet design performance. The method for controlling the rotation angle of interlaminar toughening lines in the preforming process of composite materials includes: acquiring the composite material; constructing a preforming simulation model of the fiber-reinforced material based on the deformation characteristics of the composite material during the preforming process; establishing a pre-processing finite element model; performing finite element simulation based on the preforming simulation model to obtain a predicted rotation angle; setting a target rotation angle for the toughening line and obtaining a compensation angle for the toughening line based on the predicted rotation angle; adjusting the direction of the implantation needle according to the compensation angle; and preforming and / or curing the composite material.

Description

Technical Field

[0001] This invention relates to the field of composite material molding technology, and more specifically, to a method for controlling the rotation angle of interlayer toughening lines in the preforming process of composite materials. Background Technology

[0002] Liquid molding and thermoforming are typical methods for manufacturing composite materials. To address the shortcomings of traditional laminated materials in resisting delamination, interlaminar toughening is often used to improve the delamination resistance of the final composite structure. In addition to ensuring high molding precision and few manufacturing defects, the manufacturing process of this interlaminar toughened composite structure also requires ensuring that the final orientation of the interlaminar toughening fibers is consistent with the design.

[0003] Existing interlayer toughening fibers are often implanted into multilayer fiber preforms perpendicular to the neutral layer, followed by preforming and resin curing. During the preforming process, the slippage between fibers driven by the process is difficult to avoid, resulting in deviations between the toughening fiber angular orientation and the design angle after molding, making it impossible to obtain a molded body that meets the design performance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling the rotation angle of interlaminar toughening lines in the preforming process of composite materials. This method addresses the technical problem that, during the implantation of interlaminar toughening fibers in existing composite materials, slippage between fibers causes deviations in the rotation angle of the toughening fibers from the designed angle, resulting in a molded body that fails to meet the designed performance. Therefore, this invention achieves this through the following solution.

[0005] This invention provides a method for controlling the rotation angle of interlaminar toughening lines in the preforming process of composite materials, comprising:

[0006] Obtain a composite material; the composite material comprises an upper surface, a neutral layer, and a lower surface;

[0007] Based on the deformation characteristics of the composite material during the preforming process, a preforming simulation model of the fiber-reinforced material is constructed.

[0008] Based on the geometric characteristics of the composite material structure to be formed, the property parameters of the composite material are obtained. After meshing using the preforming simulation model, the property parameters are assigned to establish a preprocessing finite element model.

[0009] Finite element simulation is performed based on the preformed simulation model to obtain the predicted rotation angle; the predicted rotation angle is the angle between the initial normal of the composite material and the neutral layer at each position after molding.

[0010] Set the target turning angle of the toughening line, and obtain the compensation angle of the toughening line based on the predicted turning angle;

[0011] The direction of the implanted needle is adjusted according to the compensation angle, and the composite material is pre-formed and / or cured.

[0012] Compared with existing technologies, the method for controlling the interlayer toughening line rotation angle in the preforming process of composite materials of the present invention, after obtaining the composite material, constructs a preforming simulation model of the fiber-reinforced material based on the deformation characteristics of the composite material during the preforming process. Then, based on the geometric characteristics of the structure to be formed, the property parameters of the composite material are obtained. After meshing using the preforming simulation model, the property parameters are assigned, thereby establishing a pre-processing finite element model. Further, by performing finite element simulation based on the preforming simulation model, the angle between the initial normal and the neutral layer at each position of the composite material after forming can be obtained, i.e., the predicted rotation angle is obtained. Based on the predicted rotation angle and the target rotation angle, the compensation angle for the implanted needle during the preforming process is obtained, and the angle of the implanted needle is determined based on the compensation angle. After compensation in degree or direction, the composite material can be pre-formed and / or cured, so that the angle of the interlayer toughening line after pre-forming and / or curing is consistent with the target angle. Furthermore, in the above technical solution of the present invention, the interlayer slippage during the molding process of complex molds can be simulated and predicted using the pre-forming simulation model. By obtaining the angle between the initial normal in the pre-forming simulation model and the neutral layer after molding, the fiber slippage before and after molding at the same point is obtained in angle form. The target angle after molding is used as the control target, and the difference between the target angle and the predicted angle is used as the input parameter. That is, the compensation angle is used as the input parameter (i.e., process parameter) in the pre-forming process. By adjusting the implantation angle of the interlayer toughening line, the angle of the interlayer toughening line after molding of the composite material is controlled to be consistent with the target angle. Through the above technical solution of the present invention, the technical problem that in the existing composite materials, due to the slippage between fibers during the implantation of interlayer toughening fibers, the orientation of the toughening fiber angle deviates from the design angle, making it impossible to obtain a molded body that meets the design performance is solved.

[0013] Furthermore, in the method for controlling the rotation angle of the interlayer toughening line in the composite material preforming process of the present invention, the compensation angle is the difference between the target rotation angle and the predicted rotation angle.

[0014] Furthermore, in the method for adjusting the angle of the interlayer toughening line in the composite material preforming process of the present invention, adjusting the direction of the implantation needle according to the compensation angle includes:

[0015] When the compensation angle is greater than zero, the implanted needle is rotated counterclockwise within the observation plane by the angle corresponding to the compensation angle.

[0016] When the compensation angle is less than zero, the implanted needle is rotated clockwise within the observation plane by the angle corresponding to the compensation angle.

[0017] Furthermore, in the method for controlling the rotation angle of the interlaminar toughening line in the preforming process of the composite material of the present invention, the process of obtaining the predicted rotation angle by performing finite element simulation based on the preforming simulation model includes:

[0018] Obtain the initial state predicted rotation angle; the initial state predicted rotation angle is the angle between the initial normal at each position before molding and the neutral layer;

[0019] When the initial normal of the composite material is rotated clockwise in the observation plane after molding, the predicted rotation angle is the difference between the predicted rotation angle of the initial state and the change value of the predicted rotation angle.

[0020] When the initial normal of the composite material is formed and rotates counterclockwise in the observation plane, the predicted rotation angle is the sum of the predicted rotation angle of the initial state and the change value of the predicted rotation angle.

[0021] Furthermore, in the method for controlling the interlaminar toughening line rotation angle during the preforming process of composite materials of the present invention, the step of constructing a preforming simulation model of the fiber-reinforced material based on the deformation characteristics of the composite material during the preforming process includes:

[0022] Based on the deformation and displacement of the composite material during the preforming process, a 3D three-node triangular continuous shell unit is constructed, and a first integration point, a second integration point, and a third integration point are set in the thickness direction of the composite material; the first integration point, the second integration point, and the third integration point are respectively located at the centroid positions of the neutral layer, the upper surface, and the lower surface of the continuous shell unit;

[0023] By utilizing the quasi-inextensibility of the fiber, the strain and corresponding stress on the upper and lower surfaces of the preformed simulation model unit are solved.

[0024] The torque is calculated by rotating the tension on the upper and lower surfaces around each node on the neutral layer. The torque causes the initial normal to rotate and determines the rotation angle of the initial normal in the preforming simulation model. The magnitude of the rotation angle represents the lateral slip of the composite material during the preforming process.

[0025] Furthermore, in the method for controlling the rotation angle of the interlayer toughening line in the preforming process of the composite material of the present invention, the rotation angle of the initial normal in the preforming simulation model can be decomposed in space into a first rotation angle and a second rotation angle in the local coordinate system.

[0026] Furthermore, in the method for controlling the rotation angle of the interlayer toughening line in the composite material preforming process of the present invention, the first rotation angle is expressed by the following formula:

[0027] ;

[0028] in, This is the sum of the torques caused by the tension at different heights within the first turning plane at a specific point. This represents the first turning angle derived from the spatial vector turning angle decomposition. Indicates the location marker represents point, The symbol for tension is indicated. This represents the total number of integration points in the thickness direction. Mark specific integration points in the thickness direction. For the third-direction parameter coordinates of a locally orthogonal coordinate system, for The thickness at the point along the direction of the rotatable normal. The markings indicating rotatable normals The tension at point k is... for The direction vector of the first coordinate axis of the local orthogonal coordinate system at the point.

[0029] Furthermore, in the method for controlling the rotation angle of the interlayer toughening line in the composite material preforming process of the present invention, the second rotation angle is expressed by the following formula:

[0030] ;

[0031] in, This is the sum of the torques caused by the tension at different heights within the second turning plane at a specific point. This represents the second rotation angle derived from the rotation decomposition of a spatial vector. Indicates the location marker represents point, The symbol for tension is indicated. This represents the total number of integration points in the thickness direction. Mark specific integration points in the thickness direction. For the third-direction parameter coordinates of a locally orthogonal coordinate system, for The thickness at the point along the direction of the rotatable normal. The markings indicating rotatable normals for Point tension, for The direction vector of the second coordinate axis of the local orthogonal coordinate system at the point.

[0032] Furthermore, in the method for controlling the interlayer toughening line angle in the composite material preforming process of the present invention, for the upper surface, lower surface, and neutral layer, wherein:

[0033] The third-direction parameter coordinate of the local orthogonal coordinate system of the upper surface is 1;

[0034] The third-direction parameter coordinate of the local orthogonal coordinate system of the lower surface is -1;

[0035] The third-direction parameter coordinate of the local orthogonal coordinate system of the neutral layer is 0.

[0036] Furthermore, in the method for controlling the rotation angle of the interlayer toughening line in the preforming process of composite materials of the present invention, the initial state predicted rotation angle is greater than 0° and less than 180°. Attached Figure Description

[0037] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0038] picture This is a schematic diagram of a composite material reinforcement containing interlayer toughening fibers according to the present invention;

[0039] Figure 2 This is a schematic diagram of a preform simulation model according to the present invention;

[0040] Figure 3 This is a two-dimensional schematic diagram of the corner of an interlayer toughening fiber according to the present invention;

[0041] Figure 4 This is a two-dimensional schematic diagram of a target rotation angle and compensation angle in this invention;

[0042] Figure 5 This is a schematic diagram illustrating the implementation of an implantation angle adjustment process in this invention;

[0043] Figure 6 A schematic diagram of an L-shaped molding process for an interlayer toughened preform of composite material in this invention. Detailed Implementation

[0044] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0045] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0047] Existing interlayer toughening fibers are often implanted into multilayer fiber preforms perpendicular to the neutral layer, followed by preforming and resin curing. During this process, due to process-driven fiber slippage during preforming, the orientation of the toughening fibers at the corners deviates from the design angle after molding, resulting in a molded body that does not meet the designed performance.

[0048] To address the aforementioned technical problems, this invention provides a method for controlling the rotation angle of interlaminar toughening lines during composite material preforming, comprising:

[0049] Obtain a composite material; the composite material comprises an upper surface, a neutral layer, and a lower surface;

[0050] Based on the deformation characteristics of the composite material during the preforming process, a preforming simulation model of the fiber-reinforced material is constructed.

[0051] Based on the geometric characteristics of the composite material structure to be formed, the property parameters of the composite material are obtained. After meshing using the preforming simulation model, the property parameters are assigned to establish a preprocessing finite element model.

[0052] Finite element simulation is performed based on the preformed simulation model to obtain the predicted rotation angle; the predicted rotation angle is the angle between the initial normal of the composite material and the neutral layer at each position after molding.

[0053] Set the target turning angle of the toughening line, and obtain the compensation angle of the toughening line based on the predicted turning angle;

[0054] The direction of the implanted needle is adjusted according to the compensation angle, and the composite material is pre-formed and / or cured.

[0055] In the above-mentioned technical solution, in the method for controlling the interlaminar toughening line rotation angle in the preforming process of composite materials of the present invention, after obtaining the composite material, a preforming simulation model of the fiber-reinforced material is constructed based on the deformation characteristics of the composite material during the preforming process. Then, based on the geometric characteristics of the structure to be formed, the property parameters of the composite material are obtained. After meshing using the preforming simulation model, the property parameters are assigned, thereby establishing a pre-processing finite element model. Further, by performing finite element simulation based on the preforming simulation model, the angle between the initial normal and the neutral layer at each position of the composite material after forming can be obtained, i.e., the predicted rotation angle is obtained. Based on the predicted rotation angle and the target rotation angle, a compensation angle for the implanted needle during the preforming process is obtained. The implanted needle is then adjusted according to the compensation angle. After compensation for the angle or direction, the composite material can be pre-formed and / or cured, so that the angle of the interlayer toughening line after pre-forming and / or curing is consistent with the target angle. Furthermore, in the above technical solution of the present invention, the interlayer slippage during the molding process of complex molds can be simulated and predicted through the pre-forming simulation model. By obtaining the angle between the initial normal in the pre-forming simulation model and the neutral layer after molding, the fiber slippage before and after molding at the same point is obtained in angle form. The target angle after molding is used as the control target, and the difference between the target angle and the predicted angle is used as the input parameter. That is, the compensation angle is used as the input parameter (i.e., process parameter) in the pre-forming process. By adjusting the implantation angle of the interlayer toughening line, the angle of the interlayer toughening line after molding of the composite material is controlled to be consistent with the target angle. Through the above technical solution of the present invention, the technical problem that in the existing composite materials, due to the slippage between fibers during the implantation of interlayer toughening fibers, the angle pose of the toughening fiber deviates from the design angle, making it impossible to obtain a molded body that meets the design performance is solved.

[0056] To better understand this invention, the following is combined with... Figures 1 to 6 The following specific embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0057] Example 1

[0058] This embodiment provides a method for controlling the rotation angle of interlaminar toughening lines in the preforming process of composite materials, including:

[0059] Step 1, Obtain the composite material; the composite material comprises an upper surface, a neutral layer, and a lower surface;

[0060] Step 2: Based on the deformation characteristics of the composite material during the preforming process, construct a preforming simulation model of the fiber-reinforced material;

[0061] Step 3: Based on the geometric characteristics of the composite material structure to be formed, obtain the property parameters of the composite material, perform mesh generation using the preforming simulation model, assign the property parameters, and establish a preprocessing finite element model;

[0062] Step 4: Perform finite element simulation based on the preformed simulation model to obtain the predicted rotation angle; the predicted rotation angle is the angle between the initial normal of the composite material at each position after molding and the neutral layer.

[0063] Step 5: Set the target turning angle of the toughening line, and obtain the compensation angle of the toughening line based on the predicted turning angle;

[0064] Step 6: Adjust the direction of the implanted needle according to the compensation angle, and pre-form and / or cure the composite material.

[0065] Example 2

[0066] This embodiment provides a method for controlling the rotation angle of interlaminar toughening lines in the preforming process of composite materials, including:

[0067] S100, Obtain a composite material; the composite material comprises an upper surface, a neutral layer, and a lower surface;

[0068] S200, Based on the deformation characteristics of the composite material during the preforming process, a preforming simulation model of the fiber-reinforced material is constructed;

[0069] Step S200 above further includes:

[0070] S201, based on the deformation and displacement of the composite material during the preforming process, a 3D three-node triangular continuous shell unit is constructed, and a first integration point, a second integration point, and a third integration point are set in the thickness direction of the composite material; the first integration point, the second integration point, and the third integration point are respectively located at the centroid positions of the neutral layer, the upper surface, and the lower surface of the continuous shell unit.

[0071] S202, using the quasi-inextensibility of the fiber, solve for the strain and corresponding stress on the upper and lower surfaces of the preformed simulation model unit;

[0072] S203, the tension on the upper and lower surfaces is used as the rotation center around each node on the neutral layer to solve for the torque; the torque causes the initial normal to rotate and determines the rotation angle of the initial normal in the preforming simulation model, the magnitude of which represents the lateral slip of the composite material during the preforming process; wherein:

[0073] The first turning angle is expressed by the following formula:

[0074] ;

[0075] in, This is the sum of the torques caused by the tension at different heights within the first turning plane at a specific point. This represents the first turning angle derived from the spatial vector turning angle decomposition. Indicates the location marker represents point, The symbol for tension is indicated. This represents the total number of integration points in the thickness direction. Mark specific integration points in the thickness direction. For the third-direction parameter coordinates of a locally orthogonal coordinate system, for The thickness at the point along the direction of the rotatable normal. The markings indicating rotatable normals The tension at point k is... for The direction vector of the first coordinate axis of the local orthogonal coordinate system at the point;

[0076] The second turning angle is expressed by the following formula:

[0077] ;

[0078] in, This is the sum of the torques caused by the tension at different heights within the second turning plane at a specific point. This represents the second rotation angle derived from the rotation decomposition of a spatial vector. Indicates the location marker represents point, The symbol for tension is indicated. This represents the total number of integration points in the thickness direction. Mark specific integration points in the thickness direction. For the third-direction parameter coordinates of a locally orthogonal coordinate system, for The thickness at the point along the direction of the rotatable normal. The markings indicating rotatable normals for Point tension, for The direction vector of the second coordinate axis of the local orthogonal coordinate system at the point;

[0079] Furthermore, for the upper surface, lower surface, and neutral layer, wherein: the third-direction parameter coordinates of the local orthogonal coordinate system of the upper surface... =1; the third-direction parameter coordinates of the local orthogonal coordinate system of the lower surface -1; the third-direction parameter coordinates of the local orthogonal coordinate system of the neutral layer. =0;

[0080] S300: Based on the geometric characteristics of the composite material structure to be formed, obtain the property parameters of the composite material, perform mesh generation using the preforming simulation model, assign the property parameters, and establish a preprocessing finite element model.

[0081] S400, perform finite element simulation based on the preformed simulation model to obtain the predicted rotation angle; the predicted rotation angle is the angle between the initial normal of the composite material at each position after molding and the neutral layer.

[0082] Further, the step of performing finite element simulation based on the preformed simulation model to obtain the predicted rotation angle includes:

[0083] S401, Obtain the initial state predicted angle; the initial state predicted angle is the angle between the initial normal at each position before molding and the neutral layer; the size of the initial state predicted angle can be: the initial state predicted angle is greater than 0° and less than 180°.

[0084] S402, when the initial normal of the composite material is formed and rotates clockwise in the observation plane, the predicted rotation angle is the difference between the initial state predicted rotation angle and the change value of the predicted rotation angle.

[0085] S403, when the initial normal of the composite material is formed and rotates counterclockwise in the observation plane, the predicted rotation angle is the sum of the initial state predicted rotation angle and the change value of the predicted rotation angle;

[0086] S500, Set the target turning angle of the toughening line, and obtain the compensation angle of the toughening line based on the predicted turning angle; the compensation angle is the difference between the target turning angle and the predicted turning angle;

[0087] S600, adjust the direction of the implanted needle according to the compensation angle, and pre-form and / or cure the composite material; wherein, during the process of adjusting the direction of the implanted needle according to the compensation angle, when the compensation angle is greater than zero, rotate the implanted needle counterclockwise within the observation plane by the angle corresponding to the compensation angle; when the compensation angle is less than zero, rotate the implanted needle clockwise within the observation plane by the angle corresponding to the compensation angle.

[0088] Example 3

[0089] This embodiment provides a method for controlling the rotation angle of interlaminar toughening lines in the preforming process of composite materials, including:

[0090] S100, Obtain a composite material; the composite material comprises an upper surface, a neutral layer, and a lower surface;

[0091] S200, Based on the deformation characteristics of the composite material during the preforming process, a preforming simulation model of the fiber-reinforced material is constructed;

[0092] Please see Figure 2 The above step S200 may further include:

[0093] S201, based on the deformation and displacement of the composite material during the preforming process, a 3D three-node triangular continuous shell unit is constructed, and a first integration point, a second integration point, and a third integration point are set in the thickness direction of the composite material; the first integration point, the second integration point, and the third integration point are respectively located at the centroid positions of the neutral layer, the upper surface, and the lower surface of the continuous shell unit.

[0094] The construction of a 3D three-node triangular continuous shell element can be achieved as follows: In the Fortran environment, the position interpolation function for constructing a three-node triangular continuous shell element is:

[0095] ;

[0096] in, The position vector obtained through parametric coordinates within the finite element method. Let be the first coordinate of the finite element intrinsic parameter coordinate system. The second coordinate of the finite element intrinsic parameter coordinate system. It is the third coordinate of the finite element intrinsic parameter coordinate system (and also the third directional parameter coordinate of the local orthogonal coordinate system). For finite element shape functions, These are the position vectors of the three nodes in the global coordinate system. for The thickness at the point along the direction of the rotatable normal. for The direction vector of the third coordinate axis of the local orthogonal coordinate system at the point. Indicates the location marker represents point, The label for rotatable normals;

[0097] Furthermore, considering the quasi-extensibility of the fibers and possible inter-fiber slippage, the above position interpolation function is adjusted to obtain the following equation:

[0098] ;

[0099] in, This is the displacement increment vector obtained through the parametric coordinates within the increment step. Let be the first coordinate of the finite element intrinsic parameter coordinate system. The second coordinate of the finite element intrinsic parameter coordinate system. It is the third coordinate of the finite element intrinsic parameter coordinate system (and also the third directional parameter coordinate of the local orthogonal coordinate system). For finite element shape functions, This represents the displacement increment vector of the three nodes in the global coordinate system. for The thickness at the point along the direction of the rotatable normal. For incremental steps The thickness increment at a point along the rotatable normal direction. Let be the increment of the first rotation angle obtained from the rotation angle decomposition of the spatial vector within the incremental step at point k. for The direction vector of the first coordinate axis of the local orthogonal coordinate system at a point. for The direction vector of the second coordinate axis in the local orthogonal coordinate system at a point. for The direction vector of the third coordinate axis of the local orthogonal coordinate system at point and is... same direction, Let be the increment of the second rotation angle derived from the rotation angle decomposition of the spatial vector within the incremental step at point k. This represents the final state of step i in the finite element calculation process. Indicates the location marker represents point, A marker indicating a rotatable normal;

[0100] Furthermore, based on the deformation mechanism and the principle of virtual work, the virtual work of the element is divided into three parts: tension, out-of-plane bending, and in-plane shear; a finite element displacement-strain matrix is ​​constructed, and the strain corresponding to different deformation modes is solved; the virtual work can be determined by the following formula:

[0101] ;

[0102] in, This is virtual work within the unit. The stretching component represents the internal virtual work. The out-of-plane bending component of the internal virtual work. The in-plane shear component represents the internal virtual work, where int represents internal; Ten represents stretching; Bend represents out-of-plane bending; and Shear represents in-plane shear.

[0103] S202, using the quasi-inextensibility of the fiber, the strain and corresponding stress on the upper and lower surfaces of the preformed simulation model unit are solved; then the stress and internal force can be solved based on the material mechanical behavior characterized in the next step.

[0104] S203, the tensile force will generate torque at the nodes, driving the initial normal to rotate; further, the torque is calculated by taking the tensile force on the upper and lower surfaces as the rotation center on each node of the neutral layer; the torque will cause the initial normal to rotate and determine the rotation angle of the initial normal in the preforming simulation model, the magnitude of which represents the lateral slip of the composite material during the preforming process; wherein:

[0105] The first turning angle is expressed by the following formula:

[0106] ;

[0107] in, This is the sum of the torques caused by the tension at different heights within the first turning plane at a specific point. This represents the first turning angle derived from the spatial vector turning angle decomposition. Indicates the location marker represents point, The symbol for tension is indicated. This represents the total number of integration points in the thickness direction. Mark specific integration points in the thickness direction. For the third-direction parameter coordinates of a locally orthogonal coordinate system, for The thickness at the point along the direction of the rotatable normal. The markings indicating rotatable normals The tension at point k is... for The direction vector of the first coordinate axis of the local orthogonal coordinate system at the point;

[0108] The second turning angle is expressed by the following formula:

[0109] ;

[0110] in, This is the sum of the torques caused by the tension at different heights within the second turning plane at a specific point. This represents the second rotation angle derived from the rotation decomposition of a spatial vector. Indicates the location marker represents point, The symbol for tension is indicated. This represents the total number of integration points in the thickness direction. Mark specific integration points in the thickness direction. For the third-direction parameter coordinates of a locally orthogonal coordinate system, for The thickness at the point along the direction of the rotatable normal. The markings indicating rotatable normals for Point tension, for The direction vector of the second coordinate axis of the local orthogonal coordinate system at the point;

[0111] Furthermore, for the upper surface, lower surface, and neutral layer, wherein: the third-direction parameter coordinates of the local orthogonal coordinate system of the upper surface... =1; the third-direction parameter coordinates of the local orthogonal coordinate system of the lower surface -1; the third-direction parameter coordinates of the local orthogonal coordinate system of the neutral layer. =0;

[0112] S300: Based on the geometric characteristics of the composite material structure to be formed, obtain the property parameters of the composite material, perform mesh generation using the preforming simulation model, assign the property parameters, and establish a preprocessing finite element model.

[0113] Further, please refer to Figure 6 In this embodiment, the geometric features of the structure to be formed are determined to be L-shaped, and the raw material to be formed is a 10-layer two-dimensional woven carbon fiber reinforced material with a length of 250 mm and a width of 40 mm. The left end of the raw material is allowed to move along the X direction, and the right end is subjected to a displacement of 70 mm to the left along the X direction and a displacement of 105 mm upward along the vertical direction. A rotational displacement of 90° is also applied to the right end, ultimately forming an L-shaped morphology. Toughening fibers are implanted at 25 mm intervals from the left end to construct a pre-processing finite element model containing the geometric features. Furthermore, the mechanical properties of the preform containing vertical interlayer toughening fibers are characterized. Tensile stiffness is obtained by single tensile test and out-of-plane bending performance is obtained by cantilever beam test. The tensile stiffness is 2300 N / mm and the out-of-plane bending stiffness is 65 N·mm.

[0114] S400, perform finite element simulation based on the preformed simulation model to obtain the predicted rotation angle; the predicted rotation angle is the angle between the initial normal of the composite material at each position after molding and the neutral layer.

[0115] The step of performing finite element simulation based on the preformed simulation model to obtain the predicted rotation angle includes:

[0116] S401, Obtain the initial state predicted angle; the initial state predicted angle is the angle between the initial normal at each position before molding and the neutral layer; the size of the initial state predicted angle can be: the initial state predicted angle is greater than 0° and less than 180°.

[0117] Further, please refer to Figure 6 In this embodiment, after performing finite element simulation, the angles between the initial normals at various locations after molding and the neutral layer in the uncontrolled state were obtained, and the predicted rotation angles at different locations 1, 2, 3, and 4 from left to right were obtained. The angles are 148°, 145°, 140°, and 122°, respectively, which were determined by rotating the initial normal counterclockwise within the observation plane.

[0118] S402, when the initial normal of the composite material is formed and rotates clockwise in the observation plane, the predicted rotation angle is the difference between the initial state predicted rotation angle and the change value of the predicted rotation angle.

[0119] S403, when the initial normal of the composite material is formed and rotates counterclockwise in the observation plane, the predicted rotation angle is the sum of the initial state predicted rotation angle and the change value of the predicted rotation angle;

[0120] S500, Set the target turning angle of the toughening line, and obtain the compensation angle of the toughening line based on the predicted turning angle; the compensation angle is the difference between the target turning angle and the predicted turning angle;

[0121] Further, please refer to Figures 3 to 5 , Figure 3 This indicates the predicted turning angle. Compared with the predicted angle change value The relationship; for example, if the initial predicted rotation angle is 90°, and the initial normal is rotated clockwise within the observation plane after forming, then: If the initial normal is rotated counterclockwise within the observation plane, then: , Take the absolute value; Figure 4 This indicates the target rotation angle after deformation. With predicted turning angle Relationship; Figure 5 This describes the process of adjusting the angle of the needle (or needle). This indicates the compensation angle; in this embodiment, the target rotation angle of the interlayer toughening line at the corresponding position after molding is set. Both are 90°. In order to achieve this target turning angle, Figure 6 Compensation angles at different locations shown The angles from left to right are -58°, -55°, -50°, and -30°.

[0122] S600, the direction of the implanted needle is adjusted according to the compensation angle, and the composite material is pre-formed and / or cured; wherein, during the process of adjusting the direction of the implanted needle according to the compensation angle, when the compensation angle is greater than zero, the implanted needle is rotated counterclockwise within the observation plane by the angle corresponding to the compensation angle; when the compensation angle is less than zero, the implanted needle is rotated clockwise within the observation plane by the angle corresponding to the compensation angle; further, in this embodiment, the implanted needle is rotated clockwise within the observation plane. Then, the composite material can be pre-formed and / or cured; according to the above description, and in conjunction with Figure 6 The technical solution of the present invention will be further described below. Figure 6 As can be seen, firstly, L-shaped preforming experiments and L-shaped preforming simulations are carried out on the composite material (i.e., fiber-reinforced material). Then, based on the model simulation, the rotation angle of the interlayer toughening fiber (i.e., interlayer toughening line) is predicted, and the initial state suture angle is adjusted based on the compensation angle (i.e., the angle or direction of the needle is adjusted). After preforming and / or curing, a molded body that meets the design performance can be obtained.

[0123] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0124] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling the rotation angle of interlayer toughening lines in the preforming process of composite materials, characterized in that, include: Obtain composite materials; The composite material comprises an upper surface, a neutral layer, and a lower surface; Based on the deformation characteristics of the composite material during the preforming process, a preforming simulation model of the fiber-reinforced material is constructed. Based on the geometric characteristics of the composite material structure to be formed, the property parameters of the composite material are obtained. After meshing using the preforming simulation model, the property parameters are assigned to establish a preprocessing finite element model. Finite element simulation is performed based on the preformed simulation model to obtain the predicted rotation angle; the predicted rotation angle is the angle between the initial normal of the composite material and the neutral layer at each position after molding. Set the target turning angle of the toughening line, and obtain the compensation angle of the toughening line based on the predicted turning angle; The direction of the implanted needle is adjusted according to the compensation angle, and the composite material is pre-formed and / or cured.

2. The method for controlling the rotation angle of interlayer toughening lines in the composite material preforming process according to claim 1, characterized in that, The compensation angle is the difference between the target turning angle and the predicted turning angle.

3. The method for controlling the rotation angle of interlayer toughening lines in the composite material preforming process according to claim 2, characterized in that, The step of adjusting the direction of the implanted needle according to the compensation angle includes: When the compensation angle is greater than zero, the implanted needle is rotated counterclockwise within the observation plane by the angle corresponding to the compensation angle. When the compensation angle is less than zero, the implanted needle is rotated clockwise within the observation plane by the angle corresponding to the compensation angle.

4. The method for controlling the rotation angle of interlayer toughening lines in the composite material preforming process according to claim 3, characterized in that, The process of obtaining the predicted rotation angle by performing finite element simulation based on the preformed simulation model includes: Obtain the initial state predicted rotation angle; the initial state predicted rotation angle is the angle between the initial normal at each position before molding and the neutral layer; When the initial normal of the composite material is rotated clockwise in the observation plane after molding, the predicted rotation angle is the difference between the predicted rotation angle of the initial state and the change value of the predicted rotation angle. When the initial normal of the composite material is formed and rotates counterclockwise in the observation plane, the predicted rotation angle is the sum of the predicted rotation angle of the initial state and the change value of the predicted rotation angle.

5. The method for controlling the rotation angle of interlayer toughening lines in the composite material preforming process according to claim 4, characterized in that, The step of constructing a preforming simulation model of the fiber-reinforced material based on the deformation characteristics of the composite material during the preforming process includes: Based on the deformation and displacement of the composite material during the preforming process, a 3D three-node triangular continuous shell unit is constructed, and a first integration point, a second integration point, and a third integration point are set in the thickness direction of the composite material; the first integration point, the second integration point, and the third integration point are respectively located at the centroid positions of the neutral layer, the upper surface, and the lower surface of the continuous shell unit; By utilizing the quasi-inextensibility of the fiber, the strain and corresponding stress on the upper and lower surfaces of the preformed simulation model unit are solved. The torque is calculated by rotating the tension on the upper and lower surfaces around each node on the neutral layer. The torque causes the initial normal to rotate and determines the rotation angle of the initial normal in the preforming simulation model. The magnitude of the rotation angle represents the lateral slip of the composite material during the preforming process.

6. The method for controlling the rotation angle of interlayer toughening lines in the composite material preforming process according to claim 5, characterized in that, In the preformed simulation model, the rotation angle of the initial normal can be decomposed in space into a first rotation angle and a second rotation angle in the local coordinate system.

7. The method for controlling the rotation angle of interlayer toughening lines in the composite material preforming process according to claim 6, characterized in that, The first turning angle is expressed by the following formula: ； in, This is the sum of the torques caused by the tension at different heights within the first turning plane at a specific point. This represents the first turning angle derived from the spatial vector turning angle decomposition. Indicates the location marker represents point, The symbol for tension is indicated. This represents the total number of integration points in the thickness direction. Mark specific integration points in the thickness direction. For the third-direction parameter coordinates of a locally orthogonal coordinate system, for The thickness at the point along the direction of the rotatable normal. The markings indicating rotatable normals The tension at point k is... for The direction vector of the first coordinate axis of the local orthogonal coordinate system at the point.

8. The method for controlling the angle of interlayer toughening lines in the composite material preforming process according to claim 7, characterized in that, The second turning angle is expressed by the following formula: ； in, This is the sum of the torques caused by the tension at different heights within the second turning plane at a specific point. This represents the second rotation angle derived from the rotation decomposition of a spatial vector. Indicates the location marker represents point, The symbol for tension is indicated. This represents the total number of integration points in the thickness direction. Mark specific integration points in the thickness direction. For the third-direction parameter coordinates of a locally orthogonal coordinate system, for The thickness at the point along the direction of the rotatable normal. The markings indicating rotatable normals for Point tension, for The direction vector of the second coordinate axis of the local orthogonal coordinate system at the point.

9. The method for controlling the angle of interlayer toughening lines in the composite material preforming process according to claim 8, characterized in that, For the upper surface, lower surface, and neutral layer, wherein: The third-direction parameter coordinate of the local orthogonal coordinate system of the upper surface is 1; The third-direction parameter coordinate of the local orthogonal coordinate system of the lower surface is -1; The third-direction parameter coordinate of the local orthogonal coordinate system of the neutral layer is 0.

10. The method for controlling the rotation angle of interlayer toughening lines in the preforming process of composite materials according to claim 9, characterized in that, The initial state prediction angle is greater than 0° and less than 180°.

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