Method and system for simulating deformation and fracture of interlaminar failure of composite laminate

Abstract

The present application belongs to the technical field of composite mechanics and computational mechanics, and discloses a method and system for simulating deformation and fracture of interlaminar failure of a composite laminate. The present application establishes an intra-layer bending bond model for each ply of the composite laminate; introduces an interlaminar normal bond and an interlaminar shear bond between adjacent plies; determines the fiber bond bending micro-modulus, the matrix bond bending micro-modulus, the interlaminar normal bond parameters and the interlaminar shear bond parameters; implements surface correction on the interlaminar normal bond and the interlaminar shear bond; respectively determines whether the interlaminar normal bond and the interlaminar shear bond fail by using the interlaminar normal relative elongation and the interlaminar shear angle between material points; and performs numerical solution on the bending control equation. The present application adopts a bond-type near-field dynamics method, does not need to preset a crack propagation path or perform mesh reconstruction, and can naturally simulate the crack initiation, propagation and interlaminar delamination process.

Description

Technical Field

[0001] This invention belongs to the field of composite material mechanics and computational mechanics, and particularly relates to a method and system for simulating deformation and fracture of interlaminar failure in composite laminates. Background Technology

[0002] Composite laminates, due to their high specific strength, specific modulus, and excellent fatigue resistance, have been widely used in aerospace, shipbuilding and marine engineering, and high-end equipment. However, in practical engineering, composite laminates often bear lateral loads and other complex external loads. Their deformation and failure behavior involves not only bending deformation within the ply but also interlaminar normal separation, interlaminar shear slip, and crack propagation between adjacent plies. Therefore, modeling and analyzing interlaminar failure and crack propagation during the bending process of composite laminates has high engineering application value.

[0003] Currently, the main analytical methods for bending problems in composite laminates include classical laminate theory, classical continuum mechanics, and the finite element method. These methods have formed relatively mature technical systems and can be effectively applied to the numerical simulation of overall bending deformation of laminates. However, when dealing with discontinuous phenomena such as crack initiation, interlaminar delamination, and crack propagation, existing methods typically require pre-setting crack paths, interface elements, or corresponding fracture criteria, and combining mesh refinement, mesh reconstruction, or contact treatment to describe the crack propagation process. For cases where the crack propagation path is unknown and interlaminar normal and shear forces coexist, these approaches usually increase the complexity of the modeling and solution process.

[0004] Perifield dynamics is a continuum modeling method based on nonlocal interactions. It describes the interaction relationships between material points through spatial integral equations and is suitable for analyzing discontinuous problems such as crack initiation and propagation. Existing composite material models based on perifield dynamics mostly focus on the analysis of deformation and failure behavior under intraplane damage, tensile fracture, or specific ply orientation conditions in single-layer plates. For the bending problem of composite laminates under transverse loads, especially involving crack propagation behavior dominated by interlaminar failure, current research still mainly focuses on intralaminar deformation analysis, and the study of interlaminar normal and interlaminar shear behavior is still incomplete. Therefore, how to establish a bond-type perifield dynamics bending modeling method that can uniformly describe intralaminar bending deformation, interlaminar normal and shear effects, and effectively simulate interlaminar failure and crack propagation processes has become an urgent technical problem to be solved in this field.

[0005] Based on the above analysis, the existing technologies have the following problems and shortcomings: insufficient characterization of interlaminar normal and interlaminar shear forces in the bending analysis of composite laminates, incomplete near-field domain at the boundary, and inadequate simulation of interlaminar failure crack propagation. Existing methods struggle to uniformly describe the intralaminar bending deformation, interlaminar normal separation, interlaminar shear slip, and crack propagation processes of composite laminates under transverse loads. Summary of the Invention

[0006] To overcome the problems existing in related technologies, the present invention discloses a method and system for simulating deformation and fracture of interlaminar failure in composite laminates, specifically involving a method for simulating bond-type near-field dynamic bending deformation and fracture damage of composite laminates considering interlaminar failure.

[0007] The technical solution is as follows: a method for simulating deformation and fracture of interlaminar failure in composite laminates, comprising the following steps: S1: Obtain the number of plies, fiber orientation, thickness, material parameters, external load conditions, and boundary conditions of the composite laminate, and discretize each ply into a set of material points; establish an intralayer bending bond model for each ply of the composite laminate. S2, based on the established intralayer bending bond model, an angle tolerance region is set with the fiber direction as the center, and the intra-family material points located within the angle tolerance region are determined as fiber bond connection objects; according to the determined fiber bond connection objects, interlayer normal bonds and interlayer shear bonds are introduced between adjacent plies; wherein, the interlayer normal bond is used to characterize the normal separation effect between corresponding material points of adjacent plies, and the interlayer shear bond is used to characterize the interlayer shear slip effect between material points in the near field region of adjacent plies; S3. Based on the principle that the near-field dynamic strain energy density is equal to the classical continuum mechanical strain energy density, the fiber bond bending micromodulus, the matrix bond bending micromodulus, the interlaminar normal bond parameter, and the interlaminar shear bond parameter are determined. S4, material points located in the boundary region and with incomplete near-field domains perform surface correction on the interlayer normal bonds and the interlayer shear bonds; S5, based on the surface correction results of the interlaminar normal bond and the interlaminar shear bond, in the intralaminar bending bond model, the interlaminar normal relative elongation and interlaminar shear angle between material points are used to determine whether the interlaminar normal bond and the interlaminar shear bond have failed; based on the judgment results, the adaptive dynamic relaxation method is used to numerically solve the bending control equation, and the results of the laminate deflection distribution, rotation angle distribution, interlaminar failure region and crack propagation path are output.

[0008] In step S1, establishing an intralayer bending bond model for each ply of the composite laminate includes: setting fiber bonds and matrix bonds within each ply, and using deflection and out-of-plane rotation as bending degrees of freedom, and material points... and Total turning angle and According to the key and Angle formed by the axis The composition is based on the rotation components, and the expression is: ; ; In the formula, The matter points are respectively at The out-of-plane rotation component of the direction; set up For matter points and Distance before deformation; For matter points and The curvature of the near-field dynamic PD bond is expressed as: ; The bending micropotential energy of the fiber bond The bending micropotential energy of the matrix bond They are respectively: ; ; In the formula, The bending micromodulus of the PD bond in the fiber direction. The bending micromodulus of the PD bond in the matrix direction.

[0009] In step S2, setting an angular tolerance region centered on the fiber direction, and defining intra-group material points located within the angular tolerance region as fiber bond connection objects, includes: The angular tolerance region is defined by an angle of [missing information] with the fiber direction as the central axis. A conical region with an angle; material points whose angle with the fiber direction is within the angular tolerance range are identified as fiber bonds; material points in the remaining layers are identified as matrix bonds; wherein... It's an angular tolerance; take the angular tolerance. for .

[0010] Furthermore, introducing interlayer normal keys and interlayer shear keys between adjacent plies includes: the interlayer normal keys exist only in the normal direction, and the interlayer shear keys exist in any direction between adjacent plies; Micropotential energy of interlayer normal bonds Defined as: ; In the formula, The first Layer, First The first layer The position vector of a material point after deformation The near-field dynamic micromodulus of the interlayer normal bond; material point With material points located between adjacent layers There exists an interlayer normal bond. , This represents the relative displacement increment generated by the interlayer normal key under normal force; After being subjected to a normal force, the bond between the two material points after deformation is: ; The micropotential energy of the interlayer shear bond for: ; In the formula, The first ply number The first material point, the first ply number The position vector of a material point before deformation. The near-field dynamic micromodulus of the interlaminar shear bond; Shear angle, For matter points and Distance before deformation; Shear angle Represented as: ; In the formula, The thickness of a single layer of the laminate. and They are respectively and Between two points and The changes in distance along the direction are expressed as follows: ; ; In the formula, The first Layer A matter point in Out-of-plane rotation component in the direction, , The first ply number A matter point in Out-of-plane rotation component in the direction; and Indicates the adjacent ply number, and or .

[0011] Furthermore, the force density of interlayer normal bonds Represented as: ; In the formula, The first The first layer The first material point, the first The first layer Deflection of a single material point; For normal key parameters; The force density components of the interlaminar shear bond are: ; ; In the formula, and Interlaminar shear bond density exist Force density component in the direction; The interlayer shear bond generates an equivalent moment density on the rotational degrees of freedom of adjacent plies through the force density component; this equivalent moment density in Components of direction , They are respectively: ; ; In the formula, For matter points The set of near-field material points in adjacent layers Indicates the first Each material point belongs to this near-field region.

[0012] In step S3, based on the principle that the near-field dynamic strain energy density is equal to the strain energy density of classical continuum mechanics, the fiber bond bending micromodulus, the matrix bond bending micromodulus, the interlaminar normal bond parameter, and the interlaminar shear bond parameter are determined, including: ; ; ; ; In the formula, The bending micromodulus of the fiber bond. The matrix bond bending micromodulus. For interlayer normal bond parameters, These are interlayer shear bond parameters. These are all parameters that constitute the flexural stiffness matrix of composite materials. The near-field radius, For the first in the near field The volume corresponding to each material point This refers to the thickness corresponding to a single-layer plate. The elastic modulus of the substrate material. The thickness of a single layer of the laminate. The equivalent volume of material points used for the equivalent derivation of interlayer normal bond parameters. The shear modulus of the substrate material. This represents the number of fiber bonded objects within the fiber direction angular tolerance region.

[0013] In step S4, for material points located in the boundary region and with incomplete near-field domains, surface correction is performed on the interlayer normal bonds and the interlayer shear bonds, including: For boundary material points located on the surface layer of the laminate, the interlayer normal bond and the interlayer shear bond The correction factors are based on the material points located on the surface layer of the laminate. The ratio of strain energy density under interlaminar normal deformation and interlaminar shear deformation conditions is determined as follows: ; ; In the formula, These represent the strain energy density according to classical continuum theory under the corresponding working conditions. These represent the strain energy densities of the near-field dynamic model under the corresponding working conditions; where, or ; This represents the total number of plies in the laminate. For material points located in non-boundary layers, the interlayer normal bonds and the interlayer shear bond No corrections will be made; For a point located in matter and The interaction between two material points is corrected by the average of the correction coefficients corresponding to the two material points. ; ; In the formula, These are the average surface correction coefficients for the corresponding interlayer bonds.

[0014] In step S5, in the intralayer bending bond model, the interlayer normal relative elongation and interlayer shear angle between material points are used to determine whether the interlayer normal bond and interlayer shear bond have failed, including: When the relative elongation of the interlaminar normal bond between material points exceeds the critical relative elongation, the interlaminar normal peri-field dynamic force between the two points disappears, the material points exhibit a localized damage state, and the peri-field dynamic force state of the material points in the dynamic equation is updated. When the interlaminar shear angle between material points exceeds the critical shear angle, the interlaminar shear peri-field dynamic force between the two points disappears, the material points exhibit a localized interlaminar damage state, and the peri-field dynamic force state of the material points in the dynamic equation is updated. When both the interlaminar normal bond and the interlaminar shear bond between two material points and all material points in their main group break, the point is in a completely damaged state, thus forming interlaminar delamination. As the interlaminar delamination phenomenon expands, the relative elongation of the interlaminar normal bond and the interlaminar shear angle between material points near the crack tip continue to increase, causing more interlaminar bonds to fail. This process is carried out simultaneously with the peri-field dynamic force calculation and the material point displacement state update. Based on the pre-constructed critical elongation function of the interlayer normal direction, the critical elongation of the interlayer normal bond is obtained. for: ; In the formula, The critical relative elongation of the interlayer normal bond. For Type I fracture energy release rate, The thickness of a single layer of the laminate. The elastic modulus of the substrate material; The critical shear angle of the interlayer shear bond is calculated based on the pre-constructed critical shear angle function. for: ; In the formula, For type II fracture energy release rate, This represents the shear modulus of the base material.

[0015] Furthermore, an adaptive dynamic relaxation method is used to numerically solve the bending control equation. At each time step, the curvature of the intralayer bending bond, the relative elongation of the interlayer normal, and the interlayer shear angle are calculated based on the current deflection and out-of-plane rotation angle of each material point. The intralayer bond state, the interlayer normal bond state, and the interlayer shear bond state are updated based on the calculation results. The updated bond state is fed back to the bending control equation, and the deflection and out-of-plane rotation angle of each material point are iteratively solved until the preset convergence condition is met.

[0016] Another object of the present invention is to provide a deformation and fracture simulation system for interlaminar failure of composite laminates. This system implements the deformation and fracture simulation method for interlaminar failure of the composite laminates. The system includes: The module for establishing the in-layer bending bond model is used to obtain the number of plies, fiber orientation, thickness, material parameters, external load conditions, and boundary conditions of the composite laminate, and to discretize each ply into a set of material points; and to establish an in-layer bending bond model for each ply of the composite laminate. The interlayer normal bond and interlayer shear bond introduction module is used to set an angle tolerance region centered on the fiber direction based on the established intralayer bending bond model, and to determine the intra-family material points located within the angle tolerance region as fiber bond connection objects; according to the determined fiber bond connection objects, interlayer normal bonds and interlayer shear bonds are introduced between adjacent plies. The parameter determination module is used to determine the fiber bond bending micromodulus, the matrix bond bending micromodulus, the interlayer normal bond parameter, and the interlayer shear bond parameter based on the principle that the near-field dynamic strain energy density is equal to the classical continuum mechanical strain energy density. A surface correction module is used to perform surface correction on the interlayer normal bonds and the interlayer shear bonds for material points located in the boundary region and with incomplete near-field domain. The module for determining whether interlaminar normal bonds and interlaminar shear bonds have failed is used to determine whether interlaminar normal bonds and interlaminar shear bonds have failed based on the surface correction results applied to the interlaminar normal bonds and interlaminar shear bonds in the intralaminar bending bond model, using the interlaminar normal relative elongation and interlaminar shear angle between material points, respectively. Based on the determination results, an adaptive dynamic relaxation method is used to numerically solve the bending control equations, and the results of laminate deflection distribution, rotation angle distribution, interlaminar failure region, and crack propagation path are output.

[0017] Combining all the above technical solutions, the beneficial effects of this invention are as follows: First, this invention introduces angular tolerances, interlaminar normal bonds, interlaminar shear bonds, and interlaminar failure criteria into the bending model of composite laminates, constructing a bond-type near-field dynamic bending deformation and fracture model applicable to arbitrary layups and considering interlaminar deformation and damage. This model can accurately simulate the bending deformation and failure behavior of composite laminates, including intralaminar and interlaminar damage. This invention determines interlaminar bond parameters and performs surface correction using the method of equal strain energy density, making it applicable to composite laminate structures with different layup forms and complex boundary conditions. This invention employs a bond-type near-field dynamics method, eliminating the need for pre-setting crack propagation paths or mesh reconstruction. It can naturally simulate crack initiation, propagation, and interlaminar delamination processes, and can simultaneously characterize intralaminar bending deformation and interlaminar damage evolution. It is suitable for analyzing intralaminar and interlaminar crack propagation problems caused by structural bending in applications such as aerospace, shipbuilding, and marine engineering.

[0018] Secondly, this invention addresses the need for deformation and interlaminar failure analysis of composite laminates under lateral and bending loads, and can output results such as laminate deflection distribution, rotation distribution, interlaminar failure regions, and crack propagation paths. This invention can predict weak areas, potential delamination locations, and crack propagation trends in laminates during the structural design stage, providing numerical basis for layup design, strength verification, damage assessment, and life analysis of composite structures, thereby reducing reliance on extensive physical experiments and repetitive finite element modeling.

[0019] Third, existing methods for analyzing the bending of composite laminates can generally describe the overall bending response well. However, when interlaminar normal separation, interlaminar shear slip, and crack propagation coexist, they often require pre-defined crack paths, interface elements, contact treatments, or mesh reconstruction, making the modeling process quite complex. This invention simultaneously sets up intralaminar bending bonds, interlaminar normal bonds, and interlaminar shear bonds in a bonded near-field dynamic bending model. This allows intralaminar bending deformation, interlaminar normal separation, interlaminar shear slip, and interlaminar damage evolution to be described within the same computational framework, thus addressing the shortcomings of existing laminate bending models in characterizing interlaminar failure coupling.

[0020] Fourth, to address the difficulty in accurately identifying fiber bond connections under arbitrary ply directions, this invention introduces an angular tolerance region centered on the fiber direction. Within this region, intra-family material points are identified as fiber bond connections, while other intra-family material points are identified as matrix bond connections. This allows the model to be applied to composite laminates with different ply angles. This invention determines intra- and inter-layer bond parameters by balancing the near-field dynamic strain energy density with the strain energy density of classical continuum mechanics. Furthermore, it performs surface correction on incomplete material points in the near-field boundary region, improving the model's applicability and computational consistency under complex boundaries and different ply structures.

[0021] Fifth, this invention employs near-field dynamics and nonlocal interactions to describe the mechanical relationships between material points. When the interlaminar normal relative elongation or interlaminar shear angle reaches the failure condition, the corresponding interlaminar bonds are directly weakened or severed, and the bond state update is fed back to the bending control equation. Therefore, crack initiation, propagation, and interlaminar delamination processes can evolve naturally with the updates of material point displacement and rotation states, without requiring a pre-defined crack propagation path or mesh reconstruction during crack propagation. This method can more continuously characterize the co-evolution of bending deformation and intralaminar and interlaminar damage in composite laminates. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the disclosure of this invention and, together with the description, serve to explain the principles of this disclosure; Figure 1This is a flowchart of the deformation and fracture simulation method for interlaminar failure of composite laminates provided in this embodiment of the invention; Figure 2 This is a schematic diagram of the deformation and fracture simulation method for interlaminar failure of composite laminates provided in this embodiment of the invention. Figure 3 A schematic diagram of the internal bending bond configuration and deformation of the composite laminate provided by the present invention; Figure 4 This is a schematic diagram of fiber bond identification under arbitrary fiber orientation provided by the present invention; Figure 5 Provided by the present invention Schematic diagram of a laminate subjected to a load in the z-direction; Figure 6 Provided by the present invention Convergence analysis diagram of laminated plate; Figure 7 The PD simulation provided by the present invention Axis rotation angle diagram, horizontal axis Represents the length direction coordinates of the laminate, with the ordinate being... Indicates the coordinates in the width direction of the laminate; color code UR1 indicates the direction around the laminate. The out-of-plane rotation angle of an axis, measured in rad; Figure 8 The PD simulation provided by the present invention Axis rotation angle diagram, horizontal axis Represents the length direction coordinates of the laminate, with the ordinate being... Indicates the coordinates in the width direction of the laminate; color code UR2 indicates the direction around the laminate. The out-of-plane rotation angle of an axis, measured in rad; Figure 9 The deflection diagram of PD simulation provided by this invention, with the horizontal axis as the x-axis. Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width of the laminate; color code U3 represents the deflection along the thickness direction, in units of... ; Figure 10 The finite element simulation provided by this invention is a winding Axis rotation angle diagram, horizontal axis Represents the length direction coordinates of the laminate, with the ordinate being... Indicates the coordinates in the width direction of the laminate; color code UR1 indicates the direction around the laminate. The out-of-plane rotation angle of an axis, measured in rad; Figure 11 The finite element simulation provided by this invention is a winding Axis rotation angle diagram, horizontal axis Represents the length direction coordinates of the laminate, with the ordinate being... Indicates the coordinates in the width direction of the laminate; color code UR2 indicates the direction around the laminate. The out-of-plane rotation angle of an axis, measured in rad; Figure 12 The deflection diagram of the finite element simulation provided by this invention, with the horizontal axis... Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width of the laminate; color code U3 represents the deflection along the thickness direction, in units of... ; Figure 13 The central vertical line winding provided by the present invention Comparison diagram of shaft rotation angles; Figure 14 The central horizontal wire winding provided by the present invention Comparison diagram of shaft rotation angles; Figure 15 A comparison diagram of the deflection of the center horizontal line provided for this invention; Figure 16 Provided by the present invention Geometric model and schematic diagram of prefabricated cracks in a case study of crack propagation in laminated slabs; Figure 17 The first layer crack propagation diagram provided for this invention; x-axis Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width direction of the laminate, and the color scales indicate the magnitude of the damage variable at the corresponding locations. Figure 18 The second layer crack propagation diagram provided by the present invention; x-axis Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width direction of the laminate, and the color scales indicate the magnitude of the damage variable at the corresponding locations. Figure 19 The third layer crack propagation diagram provided by the present invention; x-axis Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width direction of the laminate, and the color scales indicate the magnitude of the damage variable at the corresponding locations. Figure 20 The fourth layer crack propagation diagram provided by this invention; horizontal axis Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width direction of the laminate, and the color scales indicate the magnitude of the damage variable at the corresponding locations. Figure 21 The first interlayer damage map provided by this invention; x-axis Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width direction of the laminate, and the color scales indicate the magnitude of the damage variable at the corresponding locations. Figure 22 The second interlayer damage map provided by this invention; x-axis Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width direction of the laminate, and the color scales indicate the magnitude of the damage variable at the corresponding locations. Figure 23 The third interlayer damage map provided by this invention; x-axis Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width direction of the laminate, and the color scales indicate the magnitude of the damage variable at the corresponding locations. Figure 24 The fourth interlayer damage map provided by this invention; x-axis Represents the length direction coordinates of the laminate, with the ordinate being... The coordinates represent the width direction of the laminate, and the color scale indicates the magnitude of the damage variable at the corresponding location. Detailed Implementation

[0023] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0024] The innovation of this invention lies in its simultaneous introduction of intralaminar fiber bonds, intralaminar matrix bonds, interlaminar normal bonds, and interlaminar shear bonds into the near-field dynamic bending model of composite laminates. This establishes a numerical simulation method capable of uniformly describing intralaminar bending deformation, interlaminar normal separation, interlaminar shear slip, and crack propagation processes. This method identifies fiber bond connections under arbitrary ply directions through angular tolerances and determines intralaminar and interlaminar bond parameters based on the principle of equivalent strain energy density. Combined with surface correction and interlaminar failure criteria, it achieves simultaneous solutions for deflection, rotation angle, interlaminar damage, and crack propagation paths of composite laminates under bending loads. Compared to traditional methods that require pre-setting crack paths or mesh reconstruction, this invention can naturally characterize interlaminar delamination and crack propagation evolution processes within the same computational framework, making it suitable for failure analysis of composite laminates under different ply angles and complex boundary conditions.

[0025] Example 1. This invention discloses a method for simulating the near-field dynamic bending deformation and fracture damage of composite laminates considering interlaminar failure, involving bending modeling analysis and crack propagation simulation technology for composite laminates. This invention aims to solve the problem that existing methods are unable to uniformly describe the intralaminar bending deformation, interlaminar normal separation, interlaminar shear slip, and crack propagation process of composite laminates under transverse loads.

[0026] To achieve the above objectives, this invention first establishes a bond-type near-field dynamic bending model that simultaneously considers intralaminar bending and interlaminar normal and shear interactions: fiber bonds and matrix bonds are set within the ply, and interlaminar normal bonds and interlaminar shear bonds are set between adjacent plies, constructing a bending and interlaminar failure analysis model for composite laminates. Secondly, intralaminar and interlaminar bond parameters are determined through strain energy density equivalence relations, and fiber bond connections under arbitrary fiber directions are identified by combining angular tolerances, establishing a laminate bending modeling method applicable to arbitrary ply directions. Finally, boundary region surface correction, bending load application, and bond failure update processes are introduced into the model to achieve numerical simulation of interlaminar failure and crack propagation processes in composite laminates under transverse loads. Through the above methods, this invention can analyze the interlaminar failure evolution and crack propagation path of composite laminate structures under bending conditions, providing reliable numerical basis for laminate structure design, strength assessment, and life analysis.

[0027] Specifically, such as Figure 1 Deformation and fracture simulation methods for interlaminar failure in composite laminates include: S1: Obtain the number of plies, fiber orientation, thickness, material parameters, external load conditions, and boundary conditions of the composite laminate, and discretize each ply into a set of material points; establish an intralayer bending bond model for each ply of the composite laminate. For example, establishing an intralayer bending bond model for each ply of a composite laminate includes: setting fiber bonds and matrix bonds within each ply, and using deflection and out-of-plane rotation as bending degrees of freedom, and material points... and Total turning angle and According to the key and Angle formed by the axis The composition is based on the rotation components, and the expression is: ; ; In the formula, The matter points are respectively at The out-of-plane rotation component of the direction; set up For matter points and Distance before deformation; For matter points and The curvature of the peridynamic (PD) bond is expressed as: ; The bending micropotential energy of the fiber bond The bending micropotential energy of the matrix bond They are respectively: ; ; In the formula, The bending micromodulus of the PD bond in the fiber direction. The bending micromodulus of the PD bond in the matrix direction.

[0028] S2, based on the established intralayer bending bond model, an angle tolerance region is set with the fiber direction as the center, and the intra-family material points located within the angle tolerance region are determined as fiber bond connection objects; according to the determined fiber bond connection objects, interlayer normal bonds and interlayer shear bonds are introduced between adjacent plies; wherein, the interlayer normal bond is used to characterize the normal separation effect between corresponding material points of adjacent plies, and the interlayer shear bond is used to characterize the interlayer shear slip effect between material points in the near field region of adjacent plies; For example, the angular tolerance region is a region with the fiber direction as the central axis and an included angle of... A conical region with an angle. Material points whose angle with the fiber direction is within the angular tolerance range are defined as fiber bonds; material points within the remaining layers are defined as matrix bonds; wherein, It refers to angular tolerance, and angular tolerance is generally used. for As can be seen, the present invention introduces angular tolerance, thus expanding its application scope.

[0029] For example, introducing interlayer normal keys and interlayer shear keys between adjacent plies includes: the interlayer normal keys exist only in the normal direction, and the interlayer shear keys exist in any direction between adjacent plies.

[0030] The micropotential energy of the interlayer normal bond Defined as: ; In the formula, The first Layer, First The first layer The position vector of a material point after deformation The near-field dynamic micromodulus of the interlayer normal bond; material point With material points located between adjacent layers There exists an interlayer normal bond. , This represents the relative displacement increment generated by the interlayer normal key under normal force; After being subjected to a normal force, the bond between the two material points after deformation is: ; This invention improves upon existing methods by introducing the potential energy of interlayer normal bonds and shear bonds, characterizing interlayer normal separation and shear slip. The micro-potential energy of the interlayer shear bond... for: ; In the formula, The first ply number The first material point, the first ply number The position vector of a material point before deformation. The near-field dynamic micromodulus of the interlaminar shear bond; Shear angle, For matter points and Distance before deformation; Shear angle Represented as: ; In the formula, The thickness of a single layer of the laminate. and They are respectively and Between two points and The changes in distance along the direction are expressed as follows: ; ; In the formula, The first Layer A matter point in Out-of-plane rotation component in the direction, , The first ply number A matter point in Out-of-plane rotation component in the direction; and Indicates the adjacent ply number, and or .

[0031] It can be seen that, based on the original, this invention proposes an interlayer shear angle. The change in interlayer distance is used to convert the relative deformation between layers into shear angles, and the deformation form of interlayer shear is obtained from the angle difference.

[0032] For example, the present invention innovatively proposes that the force density of the interlayer normal bond can be expressed as: ; In the formula, The first The first layer The first material point, the first The first layer Deflection of a single material point; For normal key parameters; The force density components of the interlaminar shear bond are: ; ; In the formula, and Interlaminar shear bond density exist Force density component in the direction; The interlayer shear bond generates an equivalent moment density on the rotational degrees of freedom of adjacent plies through the force density component; this equivalent moment density in Components of direction , They are respectively: ; ; In the formula, For matter points The set of near-field material points in adjacent layers Indicates the first Each material point belongs to this near-field region.

[0033] S3. Based on the principle that the near-field dynamic strain energy density is equal to the classical continuum mechanical strain energy density, the fiber bond bending micromodulus, the matrix bond bending micromodulus, the interlaminar normal bond parameter, and the interlaminar shear bond parameter are determined. For example, the interlayer normal key parameter The interlaminar shear bond parameters are determined by making the near-field dynamic strain energy density under interlaminar normal deformation conditions equal to the strain energy density in classical continuum mechanics. It is determined by comparing the near-field dynamic strain energy density under simple shear conditions applied to the laminate with the strain energy density of classical continuum mechanics. Specifically: ; ; ; ; In the formula, The bending micromodulus of the fiber bond. The matrix bond bending micromodulus. For interlayer normal bond parameters, These are interlayer shear bond parameters. These are all parameters that constitute the flexural stiffness matrix of composite materials. The near-field radius, For the first in the near field The volume corresponding to each material point This refers to the thickness corresponding to a single-layer plate. The elastic modulus of the substrate material. The thickness of a single layer of the laminate. The equivalent volume of material points used for the equivalent derivation of interlayer normal bond parameters. The shear modulus of the substrate material. This represents the number of fiber bonded objects within the fiber direction angular tolerance region.

[0034] S4, material points located in the boundary region and with incomplete near-field domains perform surface correction on the interlayer normal bonds and the interlayer shear bonds; For example, this invention innovatively proposes that, for boundary material points located on the surface layer (n=1 or n=N) of a laminate, the interlayer normal bond... and the interlayer shear bond The correction factors are determined based on the ratio of strain energy density of surface layer material points under interlaminar normal deformation and interlaminar shear deformation conditions, respectively: ; ; In the formula, These represent the strain energy density according to classical continuum theory under the corresponding working conditions. These represent the strain energy densities of the near-field dynamic model under the corresponding working conditions; where, or ; This represents the total number of plies in the laminate. For example, the present invention innovatively proposes that, for material points located in non-boundary layers, the interlayer normal bond and the interlayer shear bond No corrections will be made; For a point located in matter and The interaction between two material points is corrected by the average of the correction coefficients corresponding to the two material points. ; ; In the formula, These are the average surface correction coefficients for the corresponding interlayer bonds.

[0035] S5, based on the surface correction results of the interlaminar normal bond and the interlaminar shear bond, in the intralaminar bending bond model, the interlaminar normal relative elongation and interlaminar shear angle between material points are used to determine whether the interlaminar normal bond and the interlaminar shear bond have failed; based on the judgment results, the adaptive dynamic relaxation method is used to numerically solve the bending control equation, and the results of the laminate deflection distribution, rotation angle distribution, interlaminar failure region and crack propagation path are output.

[0036] For example, in the intralayer bending bond model, the interlayer normal relative elongation and interlayer shear angle between material points are used to determine whether the interlayer normal bond and interlayer shear bond have failed, including: When the relative elongation of the interlaminar normal bond between material points exceeds the critical relative elongation, the interlaminar normal peri-field dynamic force between the two points disappears, the material points exhibit a localized damage state, and the peri-field dynamic force state of the material points in the dynamic equation is updated. When the interlaminar shear angle between material points exceeds the critical shear angle, the interlaminar shear peri-field dynamic force between the two points disappears, the material points exhibit a localized interlaminar damage state, and the peri-field dynamic force state of the material points in the dynamic equation is updated. When both the interlaminar normal bond and the interlaminar shear bond between two material points and all material points in their main group break, the point is in a completely damaged state, thus forming interlaminar delamination. As the interlaminar delamination phenomenon expands, the relative elongation of the interlaminar normal bond and the interlaminar shear angle between material points near the crack tip continue to increase, thereby causing more interlaminar bonds to fail. This process is carried out simultaneously with the peri-field dynamic force calculation and the material point displacement state update. This invention innovatively proposes that, based on a pre-constructed critical elongation function of the interlayer normal direction, the critical elongation of the interlayer normal bond can be obtained as follows: ; Calculate the critical shear angle of the interlayer shear bond based on the pre-constructed critical shear angle function: ; For example, in the process of numerically solving the bending control equation, the adaptive dynamic relaxation method calculates the curvature of the intralayer bending bond, the relative elongation of the interlayer normal direction, and the interlayer shear angle at each time step based on the current deflection and out-of-plane rotation angle of each material point, and updates the intralayer bond state, the interlayer normal bond state, and the interlayer shear bond state based on the calculation results; the updated bond state is fed back to the bending control equation, and the deflection and out-of-plane rotation angle of each material point are iteratively solved until the preset convergence condition is met.

[0037] For example, the fixed constraint end is provided with a virtual boundary layer, which is composed of three layers of virtual material point bands.

[0038] As can be seen, the present invention, based on a preset interlaminar failure judgment criterion, weakens or cuts off the corresponding interlaminar bond force when the interlaminar bond reaches the failure condition, so as to output the interlaminar failure result and crack propagation result of the composite laminate under bending load.

[0039] The bending control equations for composite laminates are constructed, and the deflection, out-of-plane rotation, intralaminar bond state, and interlaminar bond state at each material point are updated using a numerical iterative method until the convergence condition is met. The deflection distribution, rotation distribution, interlaminar failure region, and crack propagation path of the laminate are then output. As demonstrated by the above embodiments, this invention introduces angular tolerances, interlaminar normal bonds, interlaminar shear bonds, and interlaminar failure criteria into the bonded near-field dynamic bending model of composite laminates, constructing a method for simulating bonded near-field dynamic bending deformation and fracture damage that considers interlaminar failure. This method can accurately describe the interlaminar failure and crack propagation process of laminates under bending loads. This invention uses the relationship of equal strain energy density to determine interlaminar bond parameters and combines it with a boundary region surface correction method, effectively improving the computational consistency under incomplete boundary near-field domain conditions. Based on near-field dynamics theory, this invention does not require pre-setting crack propagation paths or mesh reconstruction, and can naturally simulate the evolution processes of crack initiation, propagation, and interlaminar delamination; simultaneously, it can uniformly describe the bending deformation within the ply and the normal separation and shear slip behavior between adjacent plies. The simulation results of this invention can provide reliable numerical basis for the strength analysis, failure assessment, life prediction, and structural design of composite laminate structures.

[0040] Example 2. This invention provides a deformation and fracture simulation system for interlaminar failure of composite laminates, the system comprising: The module for establishing the in-layer bending bond model is used to obtain the number of plies, fiber orientation, thickness, material parameters, external load conditions, and boundary conditions of the composite laminate, and to discretize each ply into a set of material points; and to establish an in-layer bending bond model for each ply of the composite laminate. The interlayer normal bond and interlayer shear bond introduction module is used to set an angle tolerance region centered on the fiber direction based on the established intralayer bending bond model, and to determine the intra-family material points located within the angle tolerance region as fiber bond connection objects; according to the determined fiber bond connection objects, interlayer normal bonds and interlayer shear bonds are introduced between adjacent plies. The parameter determination module is used to determine the fiber bond bending micromodulus, the matrix bond bending micromodulus, the interlayer normal bond parameter, and the interlayer shear bond parameter based on the principle that the near-field dynamic strain energy density is equal to the classical continuum mechanical strain energy density. A surface correction module is used to perform surface correction on the interlayer normal bonds and the interlayer shear bonds for material points located in the boundary region and with incomplete near-field domain. The module for determining whether interlaminar normal bonds and interlaminar shear bonds have failed is used to determine whether interlaminar normal bonds and interlaminar shear bonds have failed based on the surface correction results applied to the interlaminar normal bonds and interlaminar shear bonds in the intralaminar bending bond model, using the interlaminar normal relative elongation and interlaminar shear angle between material points, respectively. Based on the determination results, an adaptive dynamic relaxation method is used to numerically solve the bending control equations, and the results of laminate deflection distribution, rotation angle distribution, interlaminar failure region, and crack propagation path are output.

[0041] Example 3. As another embodiment of the present invention. Figure 2 The embodiment shown uses the layup sequence as follows: Using composite laminates as an example, the method of the present invention will be described. This embodiment mainly includes the following steps: Step 1: First establish The geometric model of the composite laminate is obtained to obtain the number of plies, fiber orientation of each ply, thickness of each ply, material parameters, external load conditions, and boundary conditions.

[0042] In this embodiment, the laminate has a length and width of 0.025m, and each layer has a thickness of 0.000125m. The layup sequence along the thickness direction is 0°, 45°, 45°, and 0°. The external load condition is that the left end of the laminate is fixed, and a lateral downward load of 10 N / m is applied to the right end. The material parameters selected are: fiber direction elastic modulus. Elastic modulus perpendicular to fiber direction Poisson's ratio In-plane shear modulus Elastic modulus of matrix material shear modulus of matrix material .

[0043] Step 2: As Figure 2 , Figure 5 and Figure 16As shown, the laminate is discretized into sets of material points along its length, width, and thickness directions, and a virtual boundary layer is added at the fixed end. The deformation is simulated with the left end fixed and the right end subjected to a lateral downward load of 10 N / m. The spacing between the material points is set to... dx =0.5mm. The number of discrete material points in the laminate is (50+3)×50×4. Four layers of material points are set in the thickness direction for each of the four layups. To apply fixed boundary conditions, three layers of virtual material point strips are added along the length direction at the left end of the laminate.

[0044] Step 3: As Figure 3 As shown, an intralayer bending bond model is established in each ply of the composite laminate. Fiber bonds and matrix bonds are set within each ply, and deflection and out-of-plane rotation are used as bending degrees of freedom; material points and Total turning angle and Based on the angle formed by the key and the x-axis The composition is based on the rotation components, and the expression is: ; ; set up for and The distance before deformation. Representative material point and The curvature of the PD bond can be expressed as: ; The bending micropotential energy of the fiber bond The bending micropotential energy of the matrix bond They are respectively: ; ; In the formula, It is the bending micromodulus of the PD bond in the fiber direction. It is the bending micromodulus of the PD bond in the matrix direction; Step 4: As Figure 4 As shown, an angular tolerance region is set with the fiber direction as the center, and the intra-group material points located within the angular tolerance region are defined as fiber bond connection objects; the angular tolerance region is an axis with the fiber direction as the center, and the included angle is... A tapered region with an angle. Material points whose angle with the fiber direction is within the angular tolerance range are identified as fiber bonds; material points within the remaining layers are identified as matrix bonds. In this embodiment, the angular tolerance region is preferably centered on the fiber direction as the central axis, with an included angle of . The conical region, angular tolerance for For the first and fourth layers with a 0° layup, fiber bonds are preferentially identified along the x-direction; for the second and third layers with a 45° layup, fiber bonds are preferentially identified along the x-direction. Fiber orientation identification with an angle of 45°.

[0045] Step 5: As Figure 2 , Figure 16 As shown, interlayer normal bonds and interlayer shear bonds are introduced between adjacent layers; the interlayer normal bonds exist only in the normal direction, while the interlayer shear bonds exist in any direction between adjacent layers. The micro-potential energy of the interlayer normal bonds is shown. Defined as: ; In the formula, Represented as the first Layer, First The first layer The position vector of a material point after deformation This represents the near-field dynamic micromodulus of the interlayer normal bond. And the material point... With material points located between adjacent layers There exists an interlayer normal bond. , This represents the relative displacement increment of the interlayer normal bond under normal force. After being subjected to a normal force, the bond between two material points, after deformation, is... ; The micropotential energy of the interlayer shear bond for: ; In the formula, Represented as the first ply number The first material point, the first ply number The position vector of a material point before deformation. The near-field dynamic micromodulus of the interlaminar shear bond; the shear angle Represented as: ; In the formula, The thickness of a single layer of the laminate. and They are respectively and Between two points and The changes in distance along the direction are expressed as follows: ; ; In the formula, , The first Layer A matter point in Out-of-plane rotation component in the direction, , The first ply number A matter point in Out-of-plane rotation component in the direction. and Indicates the adjacent ply number, and or .

[0046] The force density of the interlayer normal bond can be expressed as: ; In the formula, They represent the first The first layer The first material point, the first The first layer Deflection of a single material point; For normal key parameters; The force density components of the interlaminar shear bond are: ; ; In the formula, and These are interlaminar shear bond density exist Force density component in the direction.

[0047] The interlayer shear bond generates an equivalent moment density on the rotational degrees of freedom of adjacent plies through the force density component. This equivalent moment density is... Components of direction , They are: ; ; After completing this step, a complete near-field dynamic bending model is obtained, consisting of the intralayer bending behavior and interlayer interaction behavior of the laminate.

[0048] Step 6: Interlayer normal bond parameters The interlaminar shear bond parameters are determined by making the near-field dynamic strain energy density under interlaminar normal deformation conditions equal to the strain energy density in classical continuum mechanics. By applying a simple shear load to the laminate The fiber bond bending micromodulus is determined by making the near-field dynamic strain energy density equal to the strain energy density in classical continuum mechanics under the condition that only interlaminar shear bonds act on it. The matrix bond bending micromodulus The interlayer normal bond parameters and the interlayer shear bond parameters : ; ; ; ; Step 7: As Figure 2 and Figure 16 As shown, for material points located in the boundary region and with incomplete near-field domains, surface coefficient correction is applied to the interlayer normal bonds and the interlayer shear bonds; for boundary material points located on the surface layer of the laminate (n=1 or n=N), the interlayer normal bonds... and the interlayer shear bond The correction factors are determined based on the ratio of strain energy density of surface layer material points under interlaminar normal deformation and interlaminar shear deformation conditions, respectively: ; ; In the formula, These represent the strain energy density according to classical continuum theory under the corresponding working conditions. These represent the strain energy densities of the near-field dynamic model under the corresponding working conditions; where, or ; This represents the total number of plies in the laminate. For material points located in non-boundary layers, the interlayer normal bonds and the interlayer shear bond No correction is needed. And for those located at matter points... and The interaction between two material points can be corrected by the average of the correction coefficients corresponding to the two material points.

[0049] ; ; In the formula, , These represent the average surface correction coefficients for the corresponding interlayer bonds.

[0050] Step 8: In the laminate bending model, the interlaminar normal relative elongation and interlaminar shear angle between material points are used to determine whether the interlaminar normal bond and interlaminar shear bond have failed. When the interlaminar normal relative elongation between material points is greater than the critical relative elongation, the interlaminar normal near-field dynamic force between the two points disappears, the material point exhibits a local damage state, and the near-field dynamic force state of the material point in the dynamic equation is updated; when the interlaminar shear angle between material points is greater than the critical shear angle, the interlaminar shear near-field dynamic force between the two points disappears, the material point exhibits a local interlaminar damage state, and the near-field dynamic force state of the material point in the dynamic equation is updated; when both the interlaminar normal bond and the interlaminar shear bond between the two material points and all material points in their main group are broken, the point is in a completely damaged state, thus forming interlaminar delamination. As the interlaminar delamination phenomenon expands, the interlaminar normal relative elongation and interlaminar shear angle between material points near the crack tip continue to increase, thereby causing more interlaminar bonds to fail. This process is performed simultaneously with the near-field dynamic force calculation and the update of the displacement state of the material point; Based on the pre-constructed critical elongation function of the interlayer normal direction, the critical elongation of the interlayer normal bond can be obtained as follows: ; In the formula, This represents the critical relative elongation of the interlayer normal bond. Indicates the type I fracture energy release rate; Calculate the critical shear angle of the interlayer shear bond based on the pre-constructed critical shear angle function: ; In the formula, This indicates the type II fracture energy release rate.

[0051] Step 9: As Figure 2 As shown, an adaptive dynamic relaxation method is used to numerically solve the bending control equations. Within each time step, the deflection, out-of-plane rotation angle, intralayer bond state, and interlayer bond state of each material point are updated sequentially until the preset convergence condition is met. In the bending example, the convergence of the program is determined by monitoring the changes in the three degrees of freedom of a certain material point over time steps. Figure 6 As shown, the bending simulation of the [0° / 45° / 45° / 0°] laminate reached convergence at approximately 370,000 time steps.

[0052] Step 10: As Figure 7 - Figure 12 As shown in the deformation contour diagram above, under this out-of-plane load, the PD displacement contour diagram of the laminate is the same as the finite element result. Specifically, the maximum value of the laminate's rotation angle around the y-axis can reach 0.00218 rad, and the minimum deflection can reach - To further verify the accuracy of the PD results, the deflection and rotation angles of material points located on the lines x=L / 2 and y=W / 2 were extracted and compared with the finite element results, such as... Figures 13-15 As shown, the PD results are in good agreement with the finite element results. The near-field dynamic bending model of the bonded composite laminate can well simulate the bending deformation of the laminate under transverse load.

[0053] Example 4. Example 3 verified the applicability of the model established by this invention in the bending deformation analysis of laminates. Based on the same modeling approach, Example 4 further simulates crack propagation in laminates with pre-existing cracks to illustrate the unified characterization capability of this invention for intralaminar crack propagation and interlaminar damage evolution under bending loads. Unless otherwise specified, the intralaminar bond model, interlaminar bond model, parameter determination method, surface correction method, and numerical solution method in Example 4 are the same as in Example 3.

[0054] like Figure 16 As shown, [0° / 45° / 45° / 0°] laminates with a length of 1m, a width of 1m, and a layer thickness of 0.01m are applied to both ends. That is, the volumetric bending moment applied to the material point becomes Each layer of the laminate contains a pre-fabricated crack of length 2a = 0.2 m, parallel to the y-axis. This is used to simulate the crack initiation and propagation process under bending loads.

[0055] In this model, the discrete spacing between matter points is The number of discrete material points in the laminate is 100×100×4.

[0056] In the crack propagation example, such as Figures 17-20 As shown, the in-plane crack propagation results from the first to the fourth layer are presented, as follows: Figure 21 middle- Figure 24 As shown, the corresponding interlaminar damage results are presented. It can be seen that in each ply of the [0° / 45° / 45° / 0°] laminate, the intra-plane cracks all propagate from the tip of the pre-fabricated crack, exhibiting an overall X-shaped propagation trend. Whether it is interlaminar damage or intra-plane damage, the damage degree of the first and fourth layers is more pronounced than that of the second and third layers. These results demonstrate that the model established in this invention can uniformly characterize the intra-laminar crack propagation and interlaminar delamination damage evolution process of the [0° / 45° / 45° / 0°] laminate under bending loads.

[0057] In summary, Examples 3 and 4 demonstrate that the modeling of intralaminar bending deformation, interlaminar normal separation and interlaminar shear slip, interlaminar failure determination, and crack propagation simulation of [0° / 45° / 45° / 0°] composite laminates under bending loads can be completed, verifying the effectiveness of the bond-type near-field dynamics model established in this invention in the analysis of laminate bending and interlaminar failure.

[0058] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for simulating deformation and fracture of interlaminar failure in composite laminates, characterized in that, The method includes the following steps: S1: Obtain the number of plies, fiber orientation, thickness, material parameters, external load conditions, and boundary conditions of the composite laminate, and discretize each ply into a set of material points; establish an intralayer bending bond model for each ply of the composite laminate. S2, based on the established intralayer bending bond model, an angle tolerance region is set with the fiber direction as the center, and the intra-family material points located within the angle tolerance region are determined as fiber bond connection objects; according to the determined fiber bond connection objects, interlayer normal bonds and interlayer shear bonds are introduced between adjacent plies; wherein, the interlayer normal bond is used to characterize the normal separation effect between corresponding material points of adjacent plies, and the interlayer shear bond is used to characterize the interlayer shear slip effect between material points in the near field region of adjacent plies; S3. Based on the principle that the near-field dynamic strain energy density is equal to the classical continuum mechanical strain energy density, the fiber bond bending micromodulus, the matrix bond bending micromodulus, the interlaminar normal bond parameter, and the interlaminar shear bond parameter are determined. S4, material points located in the boundary region and with incomplete near-field domains perform surface correction on the interlayer normal bonds and the interlayer shear bonds; S5, based on the surface correction results of the interlaminar normal bond and the interlaminar shear bond, in the intralaminar bending bond model, the interlaminar normal relative elongation and interlaminar shear angle between material points are used to determine whether the interlaminar normal bond and the interlaminar shear bond have failed; based on the judgment results, the adaptive dynamic relaxation method is used to numerically solve the bending control equation, and the results of the laminate deflection distribution, rotation angle distribution, interlaminar failure region and crack propagation path are output.

2. The method for simulating deformation and fracture of interlaminar failure in composite laminates according to claim 1, characterized in that, In step S1, establishing an intralayer bending bond model for each ply of the composite laminate includes: setting fiber bonds and matrix bonds within each ply, and using deflection and out-of-plane rotation as bending degrees of freedom, and material points... and Total turning angle and According to the key and The included angle formed by the axis The composition is based on the rotation components, and the expression is: ； ； In the formula, The matter points are respectively at The out-of-plane rotation component of the direction; set up For matter points and Distance before deformation; For matter points and The curvature of the near-field dynamic PD bond is expressed as: ； The bending micropotential energy of the fiber bond The bending micropotential energy of the matrix bond They are respectively: ； ； In the formula, The bending micromodulus of the PD bond in the fiber direction. The bending micromodulus of the PD bond in the matrix direction.

3. The method for simulating deformation and fracture of interlaminar failure in composite laminates according to claim 1, characterized in that, In step S2, setting an angular tolerance region centered on the fiber direction, and defining intra-group material points located within the angular tolerance region as fiber bond connection objects, includes: The angular tolerance region is defined by an angle of [missing information] with the fiber direction as the central axis. A conical region with an angle; material points whose angle with the fiber direction is within the angular tolerance range are identified as fiber bonds; material points in the remaining layers are identified as matrix bonds; wherein... It's an angular tolerance; take the angular tolerance. for .

4. The method for simulating deformation and fracture of interlaminar failure in composite laminates according to claim 3, characterized in that, Introducing interlayer normal keys and interlayer shear keys between adjacent plies includes: the interlayer normal keys exist only in the normal direction, and the interlayer shear keys exist in any direction between adjacent plies; Micropotential energy of interlayer normal bonds Defined as: ； In the formula, The first Layer, First The first layer The position vector of a material point after deformation The near-field dynamic micromodulus of the interlayer normal bond; material point With material points located between adjacent layers There exists an interlayer normal bond. , This represents the relative displacement increment generated by the interlayer normal key under normal force; After being subjected to a normal force, the bond between the two material points after deformation is: ; The micropotential energy of the interlayer shear bond for: ； In the formula, The first ply number The first material point, the first ply number The position vector of a material point before deformation. The near-field dynamic micromodulus of the interlaminar shear bond; Shear angle, For matter points and Distance before deformation; Shear angle Represented as: ； In the formula, The thickness of a single layer of the laminate. and They are respectively and Between two points and The changes in distance along the direction are expressed as follows: ； ； In the formula, The first Layer A matter point in Out-of-plane rotation component in the direction, , The first ply number A matter point in Out-of-plane rotation component in the direction; and Indicates the adjacent ply number, and or .

5. The method for simulating deformation and fracture of interlaminar failure in composite laminates according to claim 4, characterized in that, Force density of interlayer normal bonds Represented as: ； In the formula, The first The first layer The first material point, the first The first layer Deflection of a single material point; For normal key parameters; The force density components of the interlaminar shear bond are: ； ； In the formula, and Interlaminar shear bond density exist Force density component in the direction; The interlayer shear bond generates an equivalent moment density on the rotational degrees of freedom of adjacent plies through the force density component; this equivalent moment density in Components of direction , They are respectively: ； ； In the formula, For matter points The set of near-field material points in adjacent layers Indicates the first Each material point belongs to this near-field region.

6. The method for simulating deformation and fracture of interlaminar failure in composite laminates according to claim 1, characterized in that, In step S3, based on the principle that the near-field dynamic strain energy density is equal to the strain energy density of classical continuum mechanics, the fiber bond bending micromodulus, the matrix bond bending micromodulus, the interlaminar normal bond parameter, and the interlaminar shear bond parameter are determined, including: ； ； ； ； In the formula, The bending micromodulus of the fiber bond. The matrix bond bending micromodulus. For interlayer normal bond parameters, These are interlayer shear bond parameters. These are all parameters that constitute the flexural stiffness matrix of composite materials. The near-field radius, For the first in the near field The volume corresponding to each material point This refers to the thickness corresponding to a single-layer plate. The elastic modulus of the substrate material. The thickness of a single layer of the laminate. The equivalent volume of material points used for the equivalent derivation of interlayer normal bond parameters. The shear modulus of the substrate material. This represents the number of fiber bonded objects within the fiber direction angular tolerance region.

7. The method for simulating deformation and fracture of interlaminar failure in composite laminates according to claim 1, characterized in that, In step S4, for material points located in the boundary region and with incomplete near-field domains, surface correction is performed on the interlayer normal bonds and the interlayer shear bonds, including: For boundary material points located on the surface layer of the laminate, the interlayer normal bond and the interlayer shear bond The correction factors are based on the material points located on the surface layer of the laminate. The ratio of strain energy density under interlaminar normal deformation and interlaminar shear deformation conditions is determined as follows: ； ； In the formula, These represent the strain energy density according to classical continuum theory under the corresponding working conditions. These represent the strain energy densities of the near-field dynamic model under the corresponding working conditions; where, or ; This represents the total number of plies in the laminate. For material points located in non-boundary layers, the interlayer normal bonds and the interlayer shear bond No corrections will be made; For a point located in matter and The interaction between two material points is corrected by the average of the correction coefficients corresponding to the two material points. ； ； In the formula, These are the average surface correction coefficients for the corresponding interlayer bonds.

8. The method for simulating deformation and fracture of interlaminar failure in composite laminates according to claim 1, characterized in that, In step S5, in the intralayer bending bond model, the interlayer normal relative elongation and interlayer shear angle between material points are used to determine whether the interlayer normal bond and interlayer shear bond have failed, including: When the relative elongation of the interlaminar normal bond between material points exceeds the critical relative elongation, the interlaminar normal peri-field dynamic force between the two points disappears, the material points exhibit a localized damage state, and the peri-field dynamic force state of the material points in the dynamic equation is updated. When the interlaminar shear angle between material points exceeds the critical shear angle, the interlaminar shear peri-field dynamic force between the two points disappears, the material points exhibit a localized interlaminar damage state, and the peri-field dynamic force state of the material points in the dynamic equation is updated. When both the interlaminar normal bond and the interlaminar shear bond between two material points and all material points in their main group break, the point is in a completely damaged state, thus forming interlaminar delamination. As the interlaminar delamination phenomenon expands, the relative elongation of the interlaminar normal bond and the interlaminar shear angle between material points near the crack tip continue to increase, causing more interlaminar bonds to fail. This process is carried out simultaneously with the peri-field dynamic force calculation and the material point displacement state update. Based on the pre-constructed critical elongation function of the interlayer normal direction, the critical elongation of the interlayer normal bond is obtained. for: ； In the formula, The critical relative elongation of the interlayer normal bond. For Type I fracture energy release rate, The thickness of a single layer of the laminate. The elastic modulus of the substrate material; The critical shear angle of the interlayer shear bond is calculated based on the pre-constructed critical shear angle function. for: ； In the formula, For type II fracture energy release rate, This represents the shear modulus of the base material.

9. The method for simulating deformation and fracture of interlaminar failure in composite laminates according to claim 8, characterized in that, An adaptive dynamic relaxation method is used to numerically solve the bending control equation. At each time step, the curvature of the intralayer bending bond, the relative elongation of the interlayer normal, and the interlayer shear angle are calculated based on the current deflection and out-of-plane rotation angle of each material point. The intralayer bond state, the interlayer normal bond state, and the interlayer shear bond state are updated based on the calculation results. The updated bond state is fed back to the bending control equation, and the deflection and out-of-plane rotation angle of each material point are iteratively solved until the preset convergence condition is met.

10. A deformation and fracture simulation system for interlaminar failure of composite laminates, characterized in that, This system implements the deformation and fracture simulation method for interlaminar failure of composite laminates as described in any one of claims 1-9, and the system comprises: The module for establishing the in-layer bending bond model is used to obtain the number of plies, fiber orientation, thickness, material parameters, external load conditions, and boundary conditions of the composite laminate, and to discretize each ply into a set of material points; and to establish an in-layer bending bond model for each ply of the composite laminate. The interlayer normal bond and interlayer shear bond introduction module is used to set an angle tolerance region centered on the fiber direction based on the established intralayer bending bond model, and to determine the intra-family material points located within the angle tolerance region as fiber bond connection objects; according to the determined fiber bond connection objects, interlayer normal bonds and interlayer shear bonds are introduced between adjacent plies. The parameter determination module is used to determine the fiber bond bending micromodulus, the matrix bond bending micromodulus, the interlayer normal bond parameter, and the interlayer shear bond parameter based on the principle that the near-field dynamic strain energy density is equal to the classical continuum mechanical strain energy density. A surface correction module is used to perform surface correction on the interlayer normal bonds and the interlayer shear bonds for material points located in the boundary region and with incomplete near-field domain. The module for determining whether interlaminar normal bonds and interlaminar shear bonds have failed is used to determine whether interlaminar normal bonds and interlaminar shear bonds have failed based on the surface correction results applied to the interlaminar normal bonds and interlaminar shear bonds in the intralaminar bending bond model, using the interlaminar normal relative elongation and interlaminar shear angle between material points, respectively. Based on the determination results, an adaptive dynamic relaxation method is used to numerically solve the bending control equations, and the results of laminate deflection distribution, rotation angle distribution, interlaminar failure region, and crack propagation path are output.

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