Layered composite material structure buckling analysis method

Abstract

The invention provides a layering-containing composite material structure buckling analysis method which comprises the following steps: establishing a layering-containing composite material finite element geometric model which comprises an upper laminated plate and a lower laminated plate, a layering is arranged between the upper laminated plate and the lower laminated plate, and adhesive layers are arranged on the two sides of the layering; determining material data of the upper and lower laminates, establishing solid shell sections of the upper and lower laminates, defining the solid shell sections and assigning the solid shell sections to the upper and lower laminates of the geometric model; determining material data of the adhesive layer, establishing a traction separation type section of the adhesive layer, defining the traction separation type section of the adhesive layer, and assigning the traction separation type section of the adhesive layer to the adhesive layer of the geometric model; assembling the upper laminated board and the lower laminated board after assignment, and binding and connecting the adhesive layer with the upper laminated board and the lower laminated board together by using a constraint to form a composite material structure simulation model; performing grid division on the simulation model; one end of the simulation model is clamped, the other end of the simulation model is freely loaded, and buckling analysis is carried out to obtain the multi-order buckling mode of the composite material structure.

Description

Technical Field

[0001] The present application belongs to the technical field of composite materials, and in particular relates to a buckling analysis method for a composite material structure containing delamination. Background Art

[0002] Composite materials are increasingly used in aircraft structures due to their advantages of light weight, good fatigue resistance, corrosion resistance and strong designability. However, composite structures are prone to delamination during manufacturing, impact damage and free edges, and the ability of composite structures with delamination to bear pressure or shear will be greatly reduced.

[0003] The prior art lacks a method for analyzing the compression or shear load points of composite structures containing delaminations. Summary of the invention

[0004] The purpose of the present application is to provide a buckling analysis method for a composite material structure containing delaminations, so as to solve or alleviate at least one problem in the background technology.

[0005] The technical solution of the present application is: a buckling analysis method for a composite material structure containing layers, comprising:

[0006] Establishing a composite material finite element geometric model containing layers, wherein the composite material finite element geometric model comprises an upper laminate and a lower laminate, wherein there is a layer between the upper laminate and the lower laminate, and both sides of the layer are adhesive layers;

[0007] Determine material data of the composite upper laminate and the composite lower laminate, establish solid shell sections of the composite upper laminate and the composite lower laminate, define the solid shell sections according to the material data of the composite upper laminate and the composite lower laminate, and assign the solid shell sections of the composite upper laminate and the composite lower laminate to the upper laminate and the lower laminate of the composite finite element geometric model;

[0008] Determine material data of the adhesive layer, establish a traction separation type cross section of the adhesive layer, define the traction separation type cross section of the adhesive layer according to the material data of the adhesive layer, and assign the traction separation type cross section of the adhesive layer to the adhesive layer of the finite element geometric model of the composite material;

[0009] Assemble the assigned upper laminate and lower laminate, and use constraints to bind the glue layer to the upper laminate and lower laminate to form a composite material structure simulation model;

[0010] Meshing of composite material structure simulation models;

[0011] One end of the composite material structure simulation model is fixed and the other end is freely loaded, and buckling analysis is performed to obtain the multi-order buckling modes of the composite material structure.

[0012] In a preferred embodiment of the present application, the composite material finite element model is established using Abaqus software.

[0013] In a preferred embodiment of the present application, the composite material upper laminate and the composite material lower laminate adopt constant type unidirectional tape, and the upper laminate and the lower laminate are obtained by laying the constant type unidirectional tape in a predetermined laying order.

[0014] In a preferred embodiment of the present application, the material performance data of the constant type unidirectional tape includes the elastic modulus and Poisson's ratio of the material.

[0015] In a preferred embodiment of the present application, the elastic modulus of the material includes a longitudinal elastic modulus, a transverse elastic modulus, a thickness direction elastic modulus, a longitudinal and transverse shear elastic modulus, a longitudinal thickness shear elastic modulus and a transverse thickness shear elastic modulus.

[0016] In a preferred embodiment of the present application, the Poisson's ratio includes the longitudinal Poisson's ratio, the longitudinal thickness Poisson's ratio, and the transverse thickness Poisson's ratio.

[0017] In a preferred embodiment of the present application, the material data of the adhesive layer includes material performance data, strength / stiffness data, damage extension data, and BK criterion strain energy release rate.

[0018] In a preferred embodiment of the present application, during the meshing process, the upper laminate and the lower laminate use solid shell elements SC8R.

[0019] In a preferred embodiment of the present application, during the meshing process, the adhesive layer uses adhesive unit COH3D8.

[0020] In a preferred embodiment of the present application, the multi-order buckling modes of the composite material structure include one or more of the first-order buckling mode, the second-order buckling mode, the third-order buckling mode, the fourth-order buckling mode and the fifth-order buckling mode.

[0021] The buckling analysis method for the delaminated composite structure of the present application uses adhesive bonding units to establish a finite element model of the delaminated composite laminate, and performs a buckling analysis to determine the buckling load. It can provide a theoretical basis for the residual strength assessment and repair of the delaminated composite structure and has high engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0023] Figure 1 Schematic diagram of the method of this application.

[0024] Figure 2Schematic diagram of the composite material finite element model in this application.

[0025] Figure 3 This is a schematic diagram of the specific dimensions of a composite material finite element model according to an embodiment of the present application.

[0026] Figure 4 A schematic diagram of a mesh of a composite material structure simulation model according to an embodiment of the present application.

[0027] Figure 5 FIG. 1 is a schematic diagram of a first-order buckling mode according to an embodiment of the present application.

[0028] Figure 6 FIG. 5 is a schematic diagram of a fifth-order buckling mode according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0030] The present application proposes a buckling analysis method for a composite material structure containing layers, so as to evaluate the bearing capacity of the composite material structure containing layers under compression or shear.

[0031] like Figure 1 As shown, the buckling analysis method for a composite material structure with delamination provided in the present application includes the following process:

[0032] Step S10: Figure 2 As shown, a composite material finite element geometric model containing a layer 14 is established. The composite material finite element geometric model 10 includes an upper laminate 11 and a lower laminate 12. The middle part between the upper and lower laminates is the layer 14, and both sides of the layer 14 are adhesive layers 13.

[0033] In this application, the finite element model of the composite material is established using Abaqus software.

[0034] like Figure 3 The figure shows a detailed dimensional schematic diagram of a composite material finite element geometric model established in an embodiment of the present application. In this embodiment, the lengths of the upper and lower layers are both 200 mm, the sum of their thicknesses is 20 mm, the length of layer 12 is 20 mm, and the rest is a glue layer.

[0035] Step S20, determine the material data of the upper and lower laminates of the composite material, lay the upper and lower laminates of the composite material using a constant type unidirectional tape in a predetermined laying order to obtain the upper and lower laminates, determine the material performance data of the constant type unidirectional tape, establish the solid shell section (Continuum Section) of the upper and lower laminates of the composite material, define the solid shell section of the composite material according to the material performance data of the unidirectional tape, give the laying angles of the upper and lower laminates and the laying coordinate system of the upper and lower laminates, and assign the solid shell section of the composite material to the upper laminate 11 and the lower laminate 12.

[0036] For example, in this embodiment of the present application, the material properties of the unidirectional tape (in MPa) are:

[0037] The longitudinal elastic modulus E1 is 135300;

[0038] The transverse elastic modulus E2 is 9000;

[0039] The elastic modulus E3 in the thickness direction is 135300;

[0040] The longitudinal and transverse Poisson's ratio Nuc12 is 0.24;

[0041] The longitudinal thickness Poisson’s ratio Nuc13 is 0.24;

[0042] The transverse thickness Poisson's ratio Nuc23 is 0.46;

[0043] The longitudinal and transverse shear elastic modulus G12 is 4500;

[0044] The longitudinal shear elastic modulus G13 is 4500;

[0045] The transverse thickness shear elastic modulus G23 is 3300.

[0046] The ply angle information of the upper and lower laminates is:

[0047] The ply of the upper laminate 11 is [45 / 0 / 45]

[0048] The layup of the lower laminate 12 is [90 / 0 / 0 / 90 / 45 / 0 / 45].

[0049] Step S30, determine the material data of the adhesive layer 13, including material performance data, strength / stiffness data, damage extension data, and BK criterion strain energy release rate, establish a traction-separation type adhesive layer cross-section, define the material data of the traction-separation type adhesive layer cross-section, and assign the traction-separation type adhesive layer cross-section to the adhesive layer 13.

[0050] For example, in this embodiment of the present application, the material properties of the adhesive layer 13 are:

[0051] The longitudinal elastic modulus E / Enn is 570000;

[0052] The transverse elastic modulus G1 / Ess is 570000;

[0053] The elastic modulus G2 / Ett in the thickness direction is 570,000.

[0054] The damage expansion data is as follows:

[0055] Type: Energy method;

[0056] Softening: Linear;

[0057] Degeneration: The Law of Maximum;

[0058] Mixed Mode Damage: BK;

[0059] Mixed mode ratio: energy;

[0060] Index: 2.284;

[0061] Normal crack extension energy index: 0.28;

[0062] Longitudinal crack extension energy index: 0.28;

[0063] Transverse crack growth energy index: 0.28.

[0064] Step S40: Assemble the above components and use constraint ties to bind the adhesive layer 13 and each laminate together to form a composite material structure simulation model.

[0065] Step S50, meshing the composite material structure simulation model, wherein the upper and lower laminates use 8-node solid shell elements SC8R, and the glue layer uses 8-node adhesive elements COH3D8, such as Figure 4 shown.

[0066] Step S60: fix one end of the composite material structure simulation model and freely load the other end, establish a buckling analysis step and submit it for analysis to obtain multi-order buckling modes of the composite material structure.

[0067] For example, in this embodiment of the present application, the buckling mode of the composite material structure obtained under the above conditions is:

[0068] First-order buckling mode: 0.99226, the first-order buckling mode is as follows Figure 5 As shown;

[0069] Second-order buckling mode: -1.0671;

[0070] Third-order buckling mode: 2.3047;

[0071] Fourth-order buckling mode: 3.7630;

[0072] Fifth-order buckling mode: 9.3415, the fifth-order buckling mode is as follows Figure 6 shown.

[0073] The buckling analysis method for the delaminated composite structure of the present application uses a cohesive element to establish a finite element model of a delaminated composite laminate, and performs a buckling analysis to determine the buckling load. This can provide a theoretical basis for the residual strength assessment and repair of delaminated composite structures and has high engineering practical value.

[0074] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A buckling analysis method for a composite material structure containing delamination, characterized in that: include: Establishing a composite material finite element geometric model containing layers, wherein the composite material finite element geometric model comprises an upper laminate and a lower laminate, wherein there is a layer between the upper laminate and the lower laminate, and both sides of the layer are adhesive layers; Determine material data of the composite upper laminate and the composite lower laminate, establish solid shell sections of the composite upper laminate and the composite lower laminate, define the solid shell sections according to the material data of the composite upper laminate and the composite lower laminate, and assign the solid shell sections of the composite upper laminate and the composite lower laminate to the upper laminate and the lower laminate of the composite finite element geometric model; Determine material data of the adhesive layer, establish a traction separation type cross section of the adhesive layer, define the traction separation type cross section of the adhesive layer according to the material data of the adhesive layer, and assign the traction separation type cross section of the adhesive layer to the adhesive layer of the composite material finite element geometric model; Assemble the assigned upper laminate and lower laminate, and use constraints to bind the glue layer to the upper laminate and lower laminate to form a composite material structure simulation model; Meshing of composite material structure simulation models; One end of the composite material structure simulation model is fixed and the other end is freely loaded, and buckling analysis is performed to obtain the multi-order buckling modes of the composite material structure.

2. The buckling analysis method for a composite material structure containing delamination according to claim 1, characterized in that: The composite material finite element model is established using Abaqus software.

3. The buckling analysis method for a composite material structure containing delamination according to claim 2, characterized in that: The composite material upper laminate and the composite material lower laminate adopt constant type unidirectional tape, and the upper laminate and the lower laminate are obtained by laying the constant type unidirectional tape in a predetermined laying sequence.

4. The buckling analysis method for a composite material structure containing delamination according to claim 3, characterized in that: The material performance data of the constant type unidirectional tape include the elastic modulus and Poisson's ratio of the material.

5. The buckling analysis method for a composite material structure containing delaminations as claimed in claim 4, characterized in that: The elastic modulus of the material includes longitudinal elastic modulus, transverse elastic modulus, thickness direction elastic modulus, longitudinal and transverse shear elastic modulus, longitudinal thickness shear elastic modulus and transverse thickness shear elastic modulus.

6. The buckling analysis method for a composite material structure containing delaminations as claimed in claim 4, characterized in that: The Poisson's ratio includes the longitudinal Poisson's ratio, the longitudinal thickness Poisson's ratio, and the transverse thickness Poisson's ratio.

7. The buckling analysis method for a composite material structure containing delamination according to claim 4, characterized in that: The material data of the adhesive layer includes material performance data, strength / rigidity data, damage extension data, and BK criterion strain energy release rate.

8. The buckling analysis method for a composite material structure containing delamination according to claim 1, characterized in that: During the meshing process, the upper laminate and the lower laminate are made of solid shell elements SC8R.

9. The buckling analysis method for a composite material structure containing delamination according to claim 1, characterized in that: During the meshing process, the adhesive layer uses the adhesive unit COH3D8.

10. The buckling analysis method for a composite material structure containing delaminations according to any one of claims 1 to 9, characterized in that: The multi-order buckling modes of the composite material structure include one or more of the first-order buckling mode, the second-order buckling mode, the third-order buckling mode, the fourth-order buckling mode and the fifth-order buckling mode.

Images