Method for regulating and controlling corner of interlayer toughening line in preforming process of composite material

Abstract

The invention discloses a method for regulating and controlling an interlayer toughening line corner in a composite material preforming process, relates to the technical field of composite material forming, and is used for solving the problems that in an interlayer toughening fiber implanting process of an existing composite material, as fibers slip, a toughening fiber corner pose is deviated from a design angle, and the toughness of the composite material is influenced. And a molded body conforming to the design performance cannot be obtained. The method for regulating and controlling the corner of the interlayer toughening line in the preforming process of the composite material comprises the following steps: obtaining the composite material; according to the deformation characteristics of the composite material in the pre-forming process, a pre-forming simulation model of the fiber reinforced material is constructed; establishing a pretreatment finite element model; performing finite element simulation according to the preformed simulation model to obtain a predicted corner; setting a target rotation angle of the toughening line, and obtaining a compensation angle of the toughening line according to the predicted rotation angle; and adjusting the direction of the implanted needle head according to the compensation angle, and performing and / or curing the composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material forming, and more specifically, to a method for controlling the turning angle of an interlayer toughening line in a composite material preforming process. Background Art

[0002] Liquid molding technology and thermoforming technology are typical representatives of composite material molding and manufacturing methods. In order to solve the insufficient anti-delamination ability of traditional laminated materials, interlayer toughening is often used to improve the anti-delamination ability of the final composite structure. In addition to ensuring high molding accuracy and few manufacturing defects, the manufacturing process of this interlayer toughened composite structure also needs to ensure that the final position of the interlayer toughening fiber is consistent with the design.

[0003] Existing interlayer toughening fibers are often implanted in a multilayer fiber preform 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 the preform containing interlayer toughening fibers having a deviation in the angle of the toughening fibers from the design angle after forming, and a molded body that meets the design performance cannot be obtained. Summary of the invention

[0004] The purpose of the present invention is to provide a method for controlling the angle of the interlayer toughening line in the preforming process of a composite material, which is used to solve the technical problem that in the process of implanting interlayer toughening fibers in the existing composite materials, the angle of the toughening fibers deviates from the designed angle due to the slippage between the fibers, and a molded body that meets the designed performance cannot be obtained. In view of this, the present invention is implemented through the following scheme.

[0005] The present invention provides a method for controlling the turning angle of interlayer toughening lines in a composite material preforming process, comprising:

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

[0007] According to the deformation characteristics of the composite material during the preforming process, a preforming simulation model of the fiber-reinforced material is constructed;

[0008] According to the geometric features of the structure to be formed of the composite material, the property parameters of the composite material are obtained, and after meshing using the preforming simulation model, the property parameters are assigned to establish a pre-processing finite element model;

[0009] Performing finite element simulation according to the preforming simulation model to obtain a predicted rotation angle; the predicted rotation angle is the angle between the initial normal line and the neutral layer of the composite material at each position after forming;

[0010] Setting a target rotation angle of the toughening line, and obtaining a compensation angle for the toughening line according to the predicted rotation angle;

[0011] The direction of the implant needle is adjusted according to the compensation angle, and the composite material is preformed and / or cured.

[0012] Compared with the prior art, in the method for controlling the angle of interlayer toughening line 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 according to the deformation characteristics of the composite material in the preforming process, and then the attribute parameters of the composite material are obtained according to the geometric characteristics of the structure to be formed of the composite material, and after meshing using the preforming simulation model, the attribute parameters are assigned, and then a pre-processing finite element model is established; further, finite element simulation is performed according to the preforming simulation model to obtain the angle between the initial normal line and the neutral layer of the composite material at each position after forming, that is, the above-mentioned predicted angle is obtained; according to the predicted angle and the target angle, a compensation angle for the implanted needle in the preforming process is obtained, and the angle of the implanted needle is adjusted according to the compensation angle After the degree or direction is compensated, the composite material can be preformed and / or cured, so that the interlayer toughening line angle after preforming and / or curing is consistent with the target angle; further, in the above technical scheme of the present invention, the above preforming simulation model can be used to realize the simulation prediction of the interlayer slip amount in the complex mold forming process, and by obtaining the angle between the initial normal line in the preforming simulation model and the neutral layer after forming, the fiber slip amount before and after forming expressed by angle at the same point is obtained, and the target angle after forming 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 preforming process, and the implantation angle of the interlayer toughening line is adjusted to make the interlayer toughening line angle of the composite material after forming consistent with the target angle. Through the above technical scheme of the present invention, the technical problem that the angle posture of the toughening fiber deviates from the design angle due to the slip between the fibers in the interlayer toughening fiber implantation process of the existing composite material is solved, and the molded body that meets the design performance cannot be obtained.

[0013] Furthermore, in the method for controlling the 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 angle and the predicted angle.

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

[0015] When the compensation angle is greater than zero, rotating the implant needle counterclockwise within the observation plane by an angle corresponding to the compensation angle;

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

[0017] Furthermore, in the method for controlling the angle of the interlayer toughening line in the composite material preforming process of the present invention, the process of performing finite element simulation according to the preforming simulation model to obtain the predicted angle includes:

[0018] Acquire an initial state predicted rotation angle; the initial state predicted rotation angle is the angle between the initial normal line and the neutral layer at each position before forming;

[0019] When the initial normal line of the composite material rotates clockwise in the observation plane after being formed, the predicted rotation angle is the difference between the predicted rotation angle in the initial state and the predicted rotation angle change value;

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

[0021] Furthermore, in the method for controlling the interlayer toughening line angle during the composite material preforming process of the present invention, the preforming simulation model of the fiber reinforced material is constructed according to the deformation characteristics of the composite material during the preforming process, including:

[0022] According to the deformation and displacement of the composite material during the preforming process, a 3D three-node triangular continuous shell element is constructed, and a first integral point, a second integral point and a third integral point are set in the thickness direction of the composite material; the first integral point, the second integral point and the third integral point are respectively located at the center of gravity of the neutral layer, the upper surface and the lower surface of the continuous shell element;

[0023] 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 tension on the upper surface and the lower surface is used to solve the torque with the nodes on the neutral layer as the rotation center; the torque will cause the initial normal line to rotate and determine the angle of the initial normal line in the preforming simulation model, and the size of the angle represents the lateral slip of the composite material during the preforming process.

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

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

[0027] ;

[0028] in, is the sum of the torques caused by the pulling forces at different heights in the first angle plane at a specific point, represents the first angle decomposed from the space vector angle, Indicates position markers represent point, Indicates the tension symbol. is the total number of integration points in the thickness direction, Mark specific integration points in the thickness direction. is the parameter coordinate of the third direction of the local orthogonal coordinate system, for The thickness along the rotatable normal direction at the point, Flag indicating rotatable normals, is the tension at point k, 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 interlayer toughening line angle in the composite material preforming process of the present invention, the second angle is represented by the following formula:

[0030] ;

[0031] in, is the sum of the torques caused by the pulling forces at different heights in the second rotation angle plane at a specific point, represents the second angle decomposed from the space vector angle, Indicates position markers represent point, Indicates the tension symbol. is the total number of integration points in the thickness direction, Mark specific integration points in the thickness direction. is the parameter coordinate of the third direction of the local orthogonal coordinate system, for The thickness along the rotatable normal direction at the point, Flag indicating rotatable normals, for Tension at point, 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, the lower surface and the neutral layer, wherein:

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

[0034] The parameter coordinate of the third direction 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 angle of the interlayer toughening line in the composite material preforming process of the present invention, the initial state predicted angle is greater than 0° and less than 180°. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 A schematic diagram of a composite material reinforcement containing interlayer toughening fibers in the present invention;

[0039] Figure 2 A schematic diagram of a preforming simulation model in the present invention;

[0040] Figure 3 It is a two-dimensional schematic diagram of the turning angle of an interlayer toughening fiber in the present invention;

[0041] Figure 4 A two-dimensional schematic diagram of a target rotation angle and a compensation angle in the present invention;

[0042] Figure 5 A schematic diagram of a process for implementing implant angle regulation in the present invention;

[0043] Figure 6 A schematic diagram of an example process of L-shaped forming of an interlayer toughening preform of a composite material in the present invention. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

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

[0046] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0047] Existing interlayer toughening fibers are often implanted in a multilayer fiber preform perpendicular to the neutral layer, followed by preforming and resin curing. In this process, due to the slippage between the fibers driven by the process during the preforming process, the preform containing interlayer toughening fibers has a deviation from the designed angle after forming, and a molded body that meets the designed performance cannot be obtained.

[0048] In order to solve the above technical problems, the present invention provides a method for controlling the interlayer toughening line angle in a composite material preforming process, comprising:

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

[0050] According to the deformation characteristics of the composite material during the preforming process, a preforming simulation model of the fiber-reinforced material is constructed;

[0051] According to the geometric features of the structure to be formed of the composite material, the property parameters of the composite material are obtained, and after meshing using the preforming simulation model, the property parameters are assigned to establish a pre-processing finite element model;

[0052] Performing finite element simulation according to the preforming simulation model to obtain a predicted rotation angle; the predicted rotation angle is the angle between the initial normal line and the neutral layer of the composite material at each position after forming;

[0053] Setting a target rotation angle of the toughening line, and obtaining a compensation angle for the toughening line according to the predicted rotation angle;

[0054] The direction of the implant needle is adjusted according to the compensation angle, and the composite material is preformed and / or cured.

[0055] In the case of adopting the above-mentioned technical scheme, in the method for controlling the angle of the interlayer toughening line in the preforming process of the composite material of the present invention, after obtaining the composite material, a preforming simulation model of the fiber-reinforced material is constructed according to the deformation characteristics of the composite material in the preforming process, and then the attribute parameters of the composite material are obtained according to the geometric characteristics of the structure to be formed of the composite material, and after meshing using the preforming simulation model, the attribute parameters are assigned, and then a pre-processing finite element model is established; further, finite element simulation is performed according to the preforming simulation model to obtain the angle between the initial normal line and the neutral layer of the composite material at each position after forming, that is, the above-mentioned predicted angle is obtained; according to the predicted angle and the target angle, a compensation angle for the implanted needle in the preforming process is obtained, and the implanted needle is adjusted according to the compensation angle. After compensating for the angle or direction of the composite material, the composite material can be preformed and / or cured, so that the interlayer toughening line angle after preforming and / or curing is consistent with the target angle; further, in the above technical scheme of the present invention, the above preforming simulation model can be used to realize the simulation prediction of the interlayer slip amount in the complex mold forming process, and by obtaining the angle between the initial normal line in the preforming simulation model and the neutral layer after forming, the fiber slip amount before and after forming expressed by angle at the same point is obtained, and the target angle after forming 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 preforming process, and the implantation angle of the interlayer toughening line is adjusted to make the interlayer toughening line angle of the composite material consistent with the target angle after forming. Through the above technical scheme of the present invention, the technical problem that the angle posture of the toughening fiber deviates from the design angle due to the slip between the fibers in the interlayer toughening fiber implantation process of the existing composite material is solved, and the molded body that meets the design performance cannot be obtained.

[0056] In order to better understand the present invention, Figures 1 to 6 , and 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 angle of interlayer toughening line in a composite material preforming process, comprising:

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

[0060] Step 2, constructing a preforming simulation model of the fiber-reinforced material according to the deformation characteristics of the composite material during the preforming process;

[0061] Step 3, obtaining the property parameters of the composite material according to the geometric features of the structure to be formed of the composite material, assigning the property parameters after meshing using the preforming simulation model, and establishing a pre-processing finite element model;

[0062] Step 4, performing finite element simulation according to the preforming simulation model to obtain a predicted rotation angle; the predicted rotation angle is the angle between the initial normal line and the neutral layer at each position of the composite material after forming;

[0063] Step 5, setting a target rotation angle of the toughening line, and obtaining a compensation angle for the toughening line according to the predicted rotation angle;

[0064] Step 6, adjusting the direction of the implant needle according to the compensation angle, and preforming and / or curing the composite material.

[0065] Example 2

[0066] This embodiment provides a method for controlling the angle of interlayer toughening line in a composite material preforming process, comprising:

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

[0068] S200, constructing a preforming simulation model of the fiber-reinforced material according to the deformation characteristics of the composite material during the preforming process;

[0069] The above step S200 further includes:

[0070] S201, constructing a 3D three-node triangular continuous shell element according to the deformation and displacement of the composite material during the preforming process, and setting a first integral point, a second integral point, and a third integral point in the thickness direction of the composite material; the first integral point, the second integral point, and the third integral point are respectively located at the centroid of the neutral layer, the upper surface, and the lower surface of the continuous shell element;

[0071] S202, using the quasi-inextensibility of the fiber, solving the strain and corresponding stress of the upper surface and the lower surface of the preformed simulation model unit;

[0072] S203, taking the tension of the upper surface and the lower surface as the rotation center with each node on the neutral layer as the rotation center, solving the torque; the torque will cause the initial normal line to rotate and determine the rotation angle of the initial normal line in the preforming simulation model, and the size of the rotation angle represents the lateral slip amount of the composite material during the preforming process; wherein:

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

[0074] ;

[0075] in, is the sum of the torques caused by the pulling forces at different heights in the first angle plane at a specific point, represents the first angle decomposed from the space vector angle, Indicates position markers represent point, Indicates the tension symbol. is the total number of integration points in the thickness direction, Mark specific integration points in the thickness direction. is the parameter coordinate of the third direction of the local orthogonal coordinate system, for The thickness along the rotatable normal direction at the point, Flag indicating rotatable normals, is the tension at point k, for The direction vector of the first coordinate axis of the local orthogonal coordinate system at the point;

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

[0077] ;

[0078] in, is the sum of the torques caused by the pulling forces at different heights in the second rotation angle plane at a specific point, represents the second angle decomposed from the space vector angle, Indicates position markers represent point, Indicates the tension symbol. is the total number of integration points in the thickness direction, Mark specific integration points in the thickness direction. is the parameter coordinate of the third direction of the local orthogonal coordinate system, for The thickness along the rotatable normal direction at the point, Flag indicating rotatable normals, for Tension at point, for The direction vector of the second coordinate axis of the local orthogonal coordinate system at the point;

[0079] Further, for the upper surface, the lower surface and the 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;

[0080] S300, acquiring attribute parameters of the composite material according to geometric features of the structure to be formed of the composite material, assigning the attribute parameters after meshing using the preforming simulation model, and establishing a pre-processing finite element model;

[0081] S400, performing finite element simulation according to the preforming simulation model to obtain a predicted rotation angle; the predicted rotation angle is the angle between the initial normal line and the neutral layer of the composite material at each position after forming;

[0082] Further, performing finite element simulation according to the preform simulation model to obtain a predicted rotation angle includes:

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

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

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

[0086] S500, setting a target rotation angle of the toughening line, and obtaining a compensation angle for the toughening line according to the predicted rotation angle; the compensation angle is a difference between the target rotation angle and the predicted rotation angle;

[0087] S600, adjusting the direction of the implant needle according to the compensation angle, and preforming and / or curing the composite material; wherein, in the process of adjusting the direction of the implant needle according to the compensation angle, when the compensation angle is greater than zero, the implant needle is rotated counterclockwise in the observation plane by an angle corresponding to the compensation angle; when the compensation angle is less than zero, the implant needle is rotated clockwise in the observation plane by an angle corresponding to the compensation angle.

[0088] Example 3

[0089] This embodiment provides a method for controlling the angle of interlayer toughening line in a composite material preforming process, comprising:

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

[0091] S200, constructing a preforming simulation model of the fiber-reinforced material according to the deformation characteristics of the composite material during the preforming process;

[0092] See also Figure 2 , the above step S200 may further include:

[0093] S201, constructing a 3D three-node triangular continuous shell element according to the deformation and displacement of the composite material during the preforming process, and setting a first integral point, a second integral point, and a third integral point in the thickness direction of the composite material; the first integral point, the second integral point, and the third integral point are respectively located at the centroid of the neutral layer, the upper surface, and the lower surface of the continuous shell element;

[0094] Among them, the construction of 3D three-node triangular continuous shell element can be: In the Fortran environment, the three-node triangular continuous shell element is constructed, and its position interpolation function is:

[0095] ;

[0096] in, is the position vector obtained by the parameter coordinates in the finite element, is the first coordinate of the finite element internal parameter coordinate system, is the second coordinate of the finite element internal parameter coordinate system, is the third coordinate of the finite element internal parameter coordinate system (also the third direction parameter coordinate of the local orthogonal coordinate system), is the finite element shape function, are the position vectors of the three nodes in the global coordinate system, for The thickness along the rotatable normal direction at the point, for The direction vector of the third coordinate axis of the local orthogonal coordinate system at the point, Indicates position markers represent point, is the marker for rotatable normals;

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

[0098] ;

[0099] in, is the displacement increment vector obtained by the parameter coordinates within the incremental step, is the first coordinate of the finite element internal parameter coordinate system, is the second coordinate of the finite element internal parameter coordinate system, is the third coordinate of the finite element internal parameter coordinate system (also the third direction parameter coordinate of the local orthogonal coordinate system), is the finite element shape function, is the displacement increment vector of the three nodes in the global coordinate system, for The thickness along the rotatable normal direction at the point, Incremental step The thickness increment along the rotatable normal direction at the point, is the increment of the first rotation angle decomposed from the space vector rotation angle in the incremental step at point k, for The direction vector of the first coordinate axis of the local orthogonal coordinate system at the point, for The direction vector of the second coordinate axis of the local orthogonal coordinate system at the point, for The direction vector of the third coordinate axis of the local orthogonal coordinate system at the point and same direction, is the increment of the second rotation angle decomposed from the space vector rotation angle in the incremental step at point k, represents the final state of the i-th step in the finite element calculation process, Indicates position markers represent point, Flags indicating rotatable normals;

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

[0101] ;

[0102] in, is the internal virtual work of the unit, is the tensile component of the internal virtual work, is the out-of-plane bending component of the internal virtual work, is the in-plane shear component of the internal virtual work, int means internal; Ten means tension, Bend means out-of-plane bending, and Shear means in-plane shear;

[0103] S202, using the quasi-inextensibility of the fiber, solving the strain and corresponding stress of the upper surface and the lower surface of the preformed simulation model unit; and then solving the stress and internal force according to the mechanical behavior of the material characterized in the next step;

[0104] S203, the tensile force will generate torque at the node, driving the initial normal line to rotate; further, the tensile force on the upper surface and the lower surface is used as the rotation center of each node on the neutral layer to solve the torque; the torque will cause the initial normal line to rotate and determine the rotation angle of the initial normal line in the preforming simulation model, and the size of the rotation angle represents the lateral slip amount of the composite material during the preforming process; wherein:

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

[0106] ;

[0107] in, is the sum of the torques caused by the pulling forces at different heights in the first angle plane at a specific point, represents the first angle decomposed from the space vector angle, Indicates position markers represent point, Indicates the tension symbol. is the total number of integration points in the thickness direction, Mark specific integration points in the thickness direction. is the parameter coordinate of the third direction of the local orthogonal coordinate system, for The thickness along the rotatable normal direction at the point, Flag indicating rotatable normals, is the tension at point k, for The direction vector of the first coordinate axis of the local orthogonal coordinate system at the point;

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

[0109] ;

[0110] in, is the sum of the torques caused by the pulling forces at different heights in the second rotation angle plane at a specific point, represents the second angle decomposed from the space vector angle, Indicates position markers represent point, Indicates the tension symbol. is the total number of integration points in the thickness direction, Mark specific integration points in the thickness direction. is the parameter coordinate of the third direction of the local orthogonal coordinate system, for The thickness along the rotatable normal direction at the point, Flag indicating rotatable normals, for Tension at point, for The direction vector of the second coordinate axis of the local orthogonal coordinate system at the point;

[0111] Further, for the upper surface, the lower surface and the 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;

[0112] S300, acquiring attribute parameters of the composite material according to geometric features of the structure to be formed of the composite material, assigning the attribute parameters after meshing using the preforming simulation model, and establishing a pre-processing finite element model;

[0113] For further information, see Figure 6 In this embodiment, the geometric feature of the structure to be formed is 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 applied with a displacement of 70 mm to the left along the X direction and a displacement of 105 mm upward in the vertical direction, and a rotation displacement of 90° is applied to the right end, and finally an L-shaped morphology is formed; toughening fibers are implanted at a spacing of 25 mm from the left end, and a pre-processed finite element model containing geometric features is constructed; further, the mechanical properties of the preform containing vertical interlayer toughening fibers are characterized, and the tensile stiffness is obtained by a single pull test, and the out-of-plane bending performance is obtained by a cantilever beam test; the tensile stiffness is 2300 N / mm, and the out-of-plane bending stiffness is 65 N.mm;

[0114] S400, performing finite element simulation according to the preforming simulation model to obtain a predicted rotation angle; the predicted rotation angle is the angle between the initial normal line and the neutral layer of the composite material at each position after forming;

[0115] The performing finite element simulation according to the preform simulation model to obtain a predicted rotation angle comprises:

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

[0117] For further information, see Figure 6 After finite element simulation, the angle between the initial normal line at each position after molding and the neutral layer after molding in the unregulated state is obtained. The predicted rotation angles at different positions 1, 2, 3, and 4 from left to right are They are 148°, 145°, 140°, and 122°, respectively, which are determined by rotating the initial normal line counterclockwise in the observation plane;

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

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

[0120] S500, setting a target rotation angle of the toughening line, and obtaining a compensation angle for the toughening line according to the predicted rotation angle; the compensation angle is a difference between the target rotation angle and the predicted rotation angle;

[0121] For further information, see Figures 3 to 5 , Figure 3 Represents the predicted turning angle And the predicted angle change value For example, when the initial state predicted rotation angle is 90°, if the initial normal rotates clockwise in the observation plane after forming, then: ; If the initial normal rotates counterclockwise in the observation plane, then: , Take the absolute value; Figure 4 Represents the target rotation angle after deformation With predicted corner relationship; Figure 5 It shows the process of adjusting the angle of the needle. Indicates the compensation angle; in this embodiment, the target angle of the interlayer toughening line at the corresponding position after molding is set All are 90°. In order to achieve this target angle, Figure 6 Compensation angle at different positions shown From left to right, the sizes are -58°, -55°, -50° and -30°;

[0122] S600, adjusting the direction of the implant needle according to the compensation angle, and preforming and / or curing the composite material; wherein, in the process of adjusting the direction of the implant needle according to the compensation angle, when the compensation angle is greater than zero, the implant needle is rotated counterclockwise in the observation plane by an angle corresponding to the compensation angle; when the compensation angle is less than zero, the implant needle is rotated clockwise in the observation plane by an angle corresponding to the compensation angle; further, in this embodiment, the implant needle is rotated clockwise in the observation plane After that, the composite material can be preformed and / or cured; according to the above description, combined with Figure 6 The technical solution of the present invention is further described. Figure 6 It can be seen that the composite material (i.e., fiber-reinforced material) is first subjected to an L-type preforming experiment and an L-type preforming simulation. Furthermore, the rotation angle of the interlayer toughening fiber (i.e., interlayer toughening line) is predicted based on the model simulation, and the suture angle of the initial state suture line is regulated 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 a suitable manner in any one or more embodiments or examples.

[0124] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for controlling the angle of interlayer toughening line in a composite material preforming process, characterized in that: include: Obtaining composite materials; The composite material comprises an upper surface, a neutral layer and a lower surface; According to the deformation characteristics of the composite material during the preforming process, a preforming simulation model of the fiber-reinforced material is constructed; According to the geometric features of the structure to be formed of the composite material, the property parameters of the composite material are obtained, and after meshing using the preforming simulation model, the property parameters are assigned to establish a pre-processing finite element model; Performing finite element simulation according to the preforming simulation model to obtain a predicted rotation angle; the predicted rotation angle is the angle between the initial normal line and the neutral layer of the composite material at each position after forming; Setting a target rotation angle of the toughening line, and obtaining a compensation angle for the toughening line according to the predicted rotation angle; The direction of the implant needle is adjusted according to the compensation angle, and the composite material is preformed and / or cured.

2. The method for controlling the interlayer toughening line angle 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 interlayer toughening line angle in the composite material preforming process according to claim 2, characterized in that: The step of adjusting the direction of the implant needle according to the compensation angle comprises: When the compensation angle is greater than zero, rotating the implant needle counterclockwise within the observation plane by an angle corresponding to the compensation angle; When the compensation angle is less than zero, the implant needle is rotated clockwise within the observation plane by an angle corresponding to the compensation angle.

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

5. The method for controlling the interlayer toughening line angle in the composite material preforming process according to claim 4, characterized in that: The method of constructing a preforming simulation model of the fiber reinforced material according to the deformation characteristics of the composite material during the preforming process includes: According to the deformation and displacement of the composite material during the preforming process, a 3D three-node triangular continuous shell element is constructed, and a first integral point, a second integral point and a third integral point are set in the thickness direction of the composite material; the first integral point, the second integral point and the third integral point are respectively located at the center of gravity of the neutral layer, the upper surface and the lower surface of the continuous shell element; 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 tension on the upper surface and the lower surface is used to solve the torque with the nodes on the neutral layer as the rotation center; the torque will cause the initial normal line to rotate and determine the angle of the initial normal line in the preforming simulation model, and the size of the angle represents the lateral slip of the composite material during the preforming process.

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

7. The method for controlling the interlayer toughening line angle in the composite material preforming process according to claim 6, characterized in that: The first rotation angle is expressed by the following formula: ； in, is the sum of the torques caused by the pulling forces at different heights in the first angle plane at a specific point, represents the first angle decomposed from the space vector angle, Indicates position markers represent point, Indicates the tension symbol. is the total number of integration points in the thickness direction, Mark specific integration points in the thickness direction. is the parameter coordinate of the third direction of the local orthogonal coordinate system, for The thickness along the rotatable normal direction at the point, Flag indicating rotatable normals, is the tension at point k, for The direction vector of the first coordinate axis of the local orthogonal coordinate system at the point.

8. The method for controlling the interlayer toughening line angle in the composite material preforming process according to claim 7, characterized in that: The second rotation angle is expressed by the following formula: ； in, is the sum of the torques caused by the pulling forces at different heights in the second rotation angle plane at a specific point, represents the second angle decomposed from the space vector angle, Indicates position markers represent point, Indicates the tension symbol. is the total number of integration points in the thickness direction, Mark specific integration points in the thickness direction. is the parameter coordinate of the third direction of the local orthogonal coordinate system, for The thickness along the rotatable normal direction at the point, Flag indicating rotatable normals, for Tension at point, for The direction vector of the second coordinate axis of the local orthogonal coordinate system at the point.

9. The method for controlling the interlayer toughening line angle in the composite material preforming process according to claim 8, characterized in that: For the upper surface, lower surface and neutral layer, wherein: The parameter coordinate of the third direction of the local orthogonal coordinate system of the upper surface is 1; The parameter coordinate of the third direction 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 interlayer toughening line angle in the composite material preforming process according to claim 9, characterized in that: The initial state predicted rotation angle is greater than 0° and less than 180°.

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