Prediction method for thermal residual stress of quasi-continuous mesh composite material

Abstract

The invention discloses a prediction method for thermal residual stress of a quasi-continuous mesh composite material, and belongs to the field of novel composite material configuration design and model establishment. The method comprises the following steps: 1) establishing a geometric model of a convex polyhedron reinforced phase; 2) establishing a geometric model of the net-shaped structure; 3) setting the volume fraction of the convex polyhedron reinforced phases, and calculating the number of the convex polyhedron reinforced phases accommodated by the network plane; 4) calculating to obtain the position of a convex polyhedron reinforced phase; 5) inserting the established convex polyhedron reinforced phase geometric models in the planes of all the reticular structure geometric models to obtain a quasi-continuous reticular composite material geometric model; 6) performing mesh division on the continuous mesh composite material geometric model, and applying a cooling boundary condition; and inputting material attributes, performing numerical simulation on thermal mismatch behaviors in the cooling process, and obtaining the thermal residual stress distribution condition of the quasi-continuous mesh composite material. Through the method, the thermal residual stress distribution of the quasi-continuous composite material with a complex structure can be effectively predicted.

Description

Technical Field

[0001] The invention belongs to the field of novel composite material configuration design and model establishment, and specifically relates to a method for predicting thermal residual stress of a quasi-continuous mesh composite material. Background Art

[0002] Quasi-continuous network composites are a new type of composite material, in which the reinforcement is distributed around the matrix particles in a network structure. In recent years, quasi-continuous network composites have attracted the attention of many researchers and engineers. In the study of composite materials, the distribution characteristics of the reinforcement phase are one of the main factors affecting the performance. However, the reinforcement phase with a quasi-continuous network distribution will seriously affect the distribution of thermal residual stress after the composite material is cooled. Because it promotes the local volume fraction of the reinforcement phase, the residual stress gradient of the material is large and the stress is concentrated. Due to the complex microstructure caused by the quasi-continuous network distribution, it is difficult to study the distribution characteristics - the law of thermal residual stress distribution through experimental trial and error.

[0003] At present, finite element simulation technology has been maturely applied in the study of material mechanical behavior under the condition of thermal-mechanical coupling of composite materials. This technology can stably predict the elastic-plastic and thermal behavior of materials with high precision, and has successfully completed the thermal residual stress analysis work in some simple structure composite materials. However, in the face of complex quasi-continuous network composite materials, simulation prediction work is still difficult to carry out due to backward modeling technology. Therefore, the current scientific research and engineering fields urgently need a new modeling technology breakthrough, and apply it to the prediction of thermal residual stress of quasi-continuous network composite materials to meet the needs of scientific research and engineering materials research and development. Summary of the invention

[0004] The purpose of the present invention is to provide a method for predicting thermal residual stress of a quasi-continuous network composite material, in view of the problems in the prior art such as difficulty in establishing a quasi-continuous composite material model and difficulty in predicting the influence law of thermal residual stress.

[0005] The specific technical solutions adopted by the present invention are as follows:

[0006] The present invention provides a method for predicting thermal residual stress of a quasi-continuous mesh composite material, and the specific steps are as follows:

[0007] S1: In the three-dimensional modeling software, a geometric model of the convex polyhedron reinforcement phase is established according to the geometric parameters of the convex polyhedron reinforcement phase;

[0008] S2: Setting mesh structure parameters and establishing mesh structure geometric model;

[0009] S3: setting the volume fraction of the convex polyhedral reinforcement phase, and calculating the number of convex polyhedral reinforcement phases accommodated in the network plane based on the network structure geometric model obtained in step S2;

[0010] S4: based on the number of convex polyhedral reinforcement phases accommodated in the network plane calculated in step S3, the position of the convex polyhedral reinforcement phase is calculated;

[0011] S5: Based on the position of the convex polyhedron reinforcement phase obtained in step S4, the convex polyhedron reinforcement phase geometric model established in step S1 is inserted in the plane of all the network structure geometric models to obtain a quasi-continuous network composite material geometric model;

[0012] S6: Meshing the geometric model of the quasi-continuous mesh composite material obtained in step S5, and applying cooling boundary conditions; inputting material properties, numerically simulating the thermal mismatch behavior of the quasi-continuous mesh composite material during the cooling process, and obtaining the thermal residual stress distribution of the quasi-continuous mesh composite material.

[0013] Preferably, the geometric parameters of the convex polyhedron reinforcement phase in step S1 include the volume of the convex polyhedron and the radius of the circumscribed circle of the cross section of the XOY plane; the center point of the convex polyhedron reinforcement phase is the origin of the Cartesian coordinate system O(0, 0, 0), and the convex polyhedron reinforcement is mirror-symmetric with respect to the XOY plane and rotationally symmetric with an even number of times about the Z axis.

[0014] Preferably, the number of network plane edges of the mesh structure geometric model in step S2 is not less than 4, the internal angle of the network plane is not less than 90°, and the average aspect ratio of the network plane is not higher than 2:1.

[0015] Preferably, the mesh structure parameters in step S2 include model size, number of mesh cells and angular distribution of average angle of network plane.

[0016] Preferably, the network plane in step S3 accommodates the number N of convex polyhedral enhancement phases. i The calculation method is as follows:

[0017] S31: Calculate the total number N of convex polyhedral reinforcement phases:

[0018]

[0019] Where: VF is the volume fraction of the convex polyhedron reinforcement phase; VP is the volume of the convex polyhedron reinforcement phase; L is the model size;

[0020] S32: Calculate the area ratio sr of the i-th network plane in the mesh structure geometry model i :

[0021]

[0022] Where: S i is the area of ​​the ith network plane, S net is the total area of ​​the mesh structure geometric model;

[0023] S33: Calculate the number of convex polyhedron enhancement phases N accommodated by the i-th network plane i =N×sr i .

[0024] Preferably, the specific method for calculating the position of the convex polyhedron reinforcement phase in step S4 is as follows:

[0025] S41: Calculate the center O of the i-th network plane i (X i , Y i , Z i ):

[0026]

[0027] Where: ∑V i,j is the node coordinates and NV of the ith network plane i is the number of nodes in the network plane;

[0028] S42: Calculate a new plane based on the i-th network plane:

[0029] Extract all the edges of the i-th network plane and point them towards the center O of the network plane. i The length of the radius of the circumscribed circle of the cross section of the XOY plane is translated; the figure enclosed by the translated edges is the new plane Si_new;

[0030] S43: Generate N in the new plane Si_new i points, and the distance between any two points is not less than the length of the radius of the circumscribed circle of the cross section of the two XOY planes; the generated N i The coordinate positions of the points are taken as the first set Set-Node i , respectively represent the position of the convex polyhedron reinforcement phase in the network plane.

[0031] Preferably, the specific steps of establishing the geometric model of the quasi-continuous network composite material in step S5 are as follows:

[0032] S51: Calculate the rotation axis Raxis of the convex polyhedral reinforcement phase in the i-th network plane:

[0033] Raxis=(VN i +Zaxis) / 2

[0034] Where: VN i is the normal vector of the ith network plane, and Zaxis is the unit vector in the Z direction of the network plane;

[0035] S52: With the rotation axis Raxis as the axis, the convex polyhedron reinforcement phase is spatially rotated at a rotation angle of 180° to obtain a new convex polyhedron reinforcement phase Polyhedron_i;

[0036] S53: According to the first set Set-Node i The coordinate position of each point in the network is respectively moved from the Cartesian coordinate system origin O(0, 0, 0) to insert the convex polyhedron reinforcement phase into the i-th network plane;

[0037] S54: Repeat steps S51 to S53, insert convex polyhedral reinforcement phases into all network planes, and gather all convex polyhedral reinforcement phases into the second set REINFORCEMENT to obtain the reinforcement phase geometric model of the composite material; draw a cube with the Cartesian coordinate system origin O (0, 0, 0) and the point (L, L, L) as the minimum and maximum points respectively to obtain the matrix geometric model; assemble the reinforcement phase geometric model and the matrix geometric model of the composite material to obtain a quasi-continuous network composite material geometric model.

[0038] Preferably, the mesh type in the mesh division described in step S6 is a 4-node tetrahedral unit, and the total number of mesh units is not less than 700,000.

[0039] Preferably, the cooling boundary conditions in step S6 are set as follows: the high temperature T1 is not greater than 1200°C, the low temperature T0 is not less than -100°C, and the cooling rate ΔT is 80-120°C.

[0040] Preferably, in step S6, finite element software ABAQUS is used for numerical simulation.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The method provided by the present invention effectively solves the problem of difficulty in establishing a geometric model of a quasi-continuous composite material. The method has low modeling difficulty, simple steps, and can support different types of reinforcement phase shapes.

[0043] (2) The present invention predicts the thermal residual stress distribution of the quasi-continuous composite material geometric model through simulation technology. The method provided by the present invention can generate distributed particle shapes, and the relationship between the enhanced phase space distribution characteristics and the thermal residual stress distribution can be established through high-throughput calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The geometric model of the convex polyhedron reinforcement phase established in Example 1;

[0045] Figure 2The mesh structure geometric model established in Example 1;

[0046] Figure 3 is the geometric model of the quasi-continuous network composite material obtained in Example 1;

[0047] Figure 4 This is a simulated cloud diagram of thermal residual stress of the quasi-continuous network composite material in Example 1. DETAILED DESCRIPTION

[0048] The present invention is further described and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0049] The present invention provides a method for predicting thermal residual stress of a quasi-continuous mesh composite material, and the specific method is as follows:

[0050] 1. Establish the geometric model of convex polyhedron reinforcement phase.

[0051] In the three-dimensional modeling software, a geometric model of the convex polyhedron reinforcement phase is established according to the geometric parameters of the convex polyhedron reinforcement phase. Among them, the geometric parameters of the convex polyhedron reinforcement phase include the volume VP of the convex polyhedron and the radius RP of the cross-section circumscribed circle of the XOY plane. The obtained convex polyhedron reinforcement phase has the following characteristics: the center point is the origin of the Cartesian coordinate system O (0, 0, 0), the convex polyhedron reinforcement phase is mirror symmetric with respect to the XOY plane, and is even-numbered rotationally symmetric about the Z axis.

[0052] It should be noted that the 3D modeling software can be AutoCAD, CINEMA 4D, SolidWorks, NX, Rhinoceros, MAYA, 3DMAX or Blender software.

[0053] 2. Establish a mesh structure geometric model.

[0054] In commercial software or open source software packages, set mesh structure parameters and establish a mesh structure geometric model. The mesh structure geometric model has the following characteristics: the number of network plane edges is not less than 4, the internal angle of the network plane is not less than 90°, and the average aspect ratio of the network plane is not higher than 2:1.

[0055] It should be noted that the commercial software may be AutoCAD, CINEMA 4D, Rhinoceros or MATLAB, and the open source software package may be Blender, Neper or Scipy.

[0056] 3. Calculate the number of convex polyhedral enhancement phases that the network plane can accommodate.

[0057] (1) Calculate the total number N of convex polyhedral reinforcement phases:

[0058]

[0059] Where: VF is the volume fraction of the convex polyhedron reinforcement phase; VP is the volume of the convex polyhedron reinforcement phase; L is the model size.

[0060] Perform the following operations on each network plane:

[0061] (2) Calculate the area ratio sr of the i-th network plane in the mesh structure geometric model i :

[0062]

[0063] Where: S i is the area of ​​the ith network plane, S net is the total area of ​​the mesh structure geometric model;

[0064] (3) Calculate the number of convex polyhedron enhancement phases N that can be accommodated by the i-th network plane i =N×sr i .

[0065] 4. Calculate the position of the convex polyhedron reinforcement phase in the network plane.

[0066] Perform the following operations on all network planes of the mesh structure geometric model:

[0067] (1) Calculate the center O of the i-th network plane i (X i , Y i , Z i ):

[0068]

[0069] Where: ∑V i,j is the node coordinates and NV of the ith network plane i is the number of nodes in the network plane;

[0070] (2) Calculate the new plane based on the i-th network plane:

[0071] Extract all the edges of the i-th network plane and point them towards the center O of the network plane. i Translate the length RP of the radius of the circumscribed circle of a cross section; the figure enclosed by the translated edge is the new plane Si_new;

[0072] (3) Randomly generate N in the new plane Si_new i points, and the distance between any two points is not less than the length RP of the radius of the circumscribed circle of the two sections; the generated N iThe coordinate positions of the points are taken as the first set Set-Node i , respectively represent the position of the convex polyhedron reinforcement phase in the network plane.

[0073] 5. Establish the geometric model of quasi-continuous mesh composite materials.

[0074] Perform the following operations on all network planes of the mesh structure geometric model:

[0075] (1) Calculate the rotation axis Raxis of the convex polyhedron reinforcement phase in the i-th network plane:

[0076] Raxis=(VN i +Zaxis) / 2

[0077] Where: VN i is the normal vector of the ith network plane, and Zaxis is the unit vector in the Z direction of the network plane;

[0078] (2) Perform spatial rotation on the convex polyhedron reinforcement phase in the i-th network plane.

[0079] With the rotation axis Raxis as the axis, the convex polyhedron reinforcement phase is spatially rotated at a rotation angle of 180° to obtain a new convex polyhedron reinforcement phase Polyhedron_i;

[0080] (3) Perform convex polyhedron enhancement phase insertion on the i-th network plane.

[0081] According to the first set Set-Node i The coordinate position of each point in the , respectively, moves the new convex polyhedron reinforcement phase Polyhedron_i from the Cartesian coordinate system origin O(0,0,0), and inserts the convex polyhedron reinforcement phase on the i-th network plane. In other words, the new convex polyhedron reinforcement phase Polyhedron_i is inserted according to the first set Set-Node i The coordinate position in the vector is moved.

[0082] For example, the first set Set-Node i There are two coordinate positions (1, 1, 1) and (2, 2, 2) in , then the two new convex polyhedron enhancement phases are translated from the origin O(0, 0, 0) by (1, 1, 1) and (2, 2, 2) respectively.

[0083] (4) Repeat steps (1) to (2), insert convex polyhedral reinforcement phases into all network planes, and collect all convex polyhedral reinforcement phases into the second set REINFORCEMENT to obtain the reinforcement phase geometric model of the composite material.

[0084] A cube is drawn with the Cartesian coordinate system origin O(0, 0, 0) and point (L, L, L) as the minimum and maximum points to obtain a base geometry model. In other words, the nodes of this cube are (0, 0, 0) and (L, L, L), and the surfaces of the cube are parallel to the XOY, YOZ, and ZOX planes, respectively.

[0085] The reinforcement phase geometric model and the matrix geometric model of the composite material are assembled to obtain a quasi-continuous network composite material geometric model.

[0086] 6. Grid division and boundary condition setting.

[0087] The obtained quasi-continuous mesh composite geometric model is meshed, and the mesh type is 4-node tetrahedral unit, and the total number of mesh units is not less than 700,000. Set the high temperature T1, low temperature T0 and cooling rate ΔT as cooling boundary conditions. The temperature field of the quasi-continuous mesh composite geometric model is reduced from T1 to T0, and it undergoes (TT) / ΔT calculation steps. The (0, 0, 0) node of the constraint model does not move or rotate during the simulation process.

[0088] 7. Finite element simulation.

[0089] Finite element software ABAQUS was used to input material properties and numerically simulate the thermal mismatch behavior of the quasi-continuous network composite material during cooling, and the thermal residual stress distribution of the quasi-continuous network composite material was obtained.

[0090] The practical application effect of the above method of the present invention will be described below through specific embodiments.

[0091] Example 1

[0092] 1. Establish the geometric model of convex polyhedron reinforcement phase.

[0093] The convex polyhedron established is a hexagonal prism, which is 6-fold rotationally symmetric about the Z axis, such as Figure 1 As shown, the volume of the convex polyhedron reinforcement phase is VP=47.0, and the radius of the circumscribed circle of the cross section of the XOY plane is RP=0.97.

[0094] 2. Establish a mesh structure geometric model.

[0095] The model size L = 100, the number of mesh cells is 24, and the network plane angle is bimodal distribution, concentrated at 60° and 120°, such as Figure 2 shown.

[0096] 3. Set the volume fraction of the convex polyhedron reinforcement phase VF = 10% and calculate the number of convex polyhedron reinforcement phases that can be accommodated in the network plane.

[0097] 4. Based on the number of convex polyhedral reinforcement phases obtained in step 3, calculate the position of the reinforcement phase in the network plane.

[0098] 5. Establish the geometric model of quasi-continuous network composite material. The obtained geometric model of quasi-continuous network composite material is as follows: Figure 3 shown.

[0099] 6. Meshing and cooling boundary conditions. The quasi-continuous mesh composite geometric model is meshed, the mesh type is 4-node tetrahedron unit, and the total number of mesh units is 1,000,000. The high temperature T1 = 500 °C, the low temperature T0 = 380 °C, and the cooling rate ΔT = 120 °C are set for the model.

[0100] 7. Using the commercial finite element software ABAQUS, the material properties are input and the thermal mismatch behavior of the quasi-continuous mesh composite material during the cooling process is numerically simulated to obtain the thermal residual stress distribution of the quasi-continuous mesh composite material.

[0101] The relationship between the material's Young's modulus (E), Poisson's ratio (λ), and expansion coefficient (α) and temperature is set as follows:

[0102]

[0103]

[0104] This embodiment establishes a composite material finite element model of a hexagonal whisker reinforcement. The model is relatively complex, and the whiskers are oriented and arranged in the plane of the network layer. Figure 4 The cross-sectional diagram of the residual stress distribution of the matrix at X=50. It can be found that the thermal residual stress distribution of the composite material is well predicted. The stress level in the reinforcement phase aggregation area is higher than 75MPa, and the residual stress increases sharply as the reinforcement phase spacing decreases. However, the residual stress level in the reinforcement phase aggregation area decreases sharply, and in the area far away from the reinforcement phase, the stress level drops to ~10MPa. It can be seen that the method provided by the present invention establishes a model that can effectively predict the thermal residual stress distribution of quasi-continuous composite materials with complex structures.

[0105] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A method for predicting thermal residual stress of a quasi-continuous network composite material, characterized in that: The specific steps are as follows: S1: In the three-dimensional modeling software, a geometric model of the convex polyhedron reinforcement phase is established according to the geometric parameters of the convex polyhedron reinforcement phase; S2: Setting mesh structure parameters and establishing mesh structure geometric model; S3: setting the volume fraction of the convex polyhedral reinforcement phase, and calculating the number of convex polyhedral reinforcement phases accommodated in the network plane based on the network structure geometric model obtained in step S2; S4: based on the number of convex polyhedral reinforcement phases accommodated in the network plane calculated in step S3, the position of the convex polyhedral reinforcement phase is calculated; S5: Based on the position of the convex polyhedron reinforcement phase obtained in step S4, the convex polyhedron reinforcement phase geometric model established in step S1 is inserted in the plane of all the network structure geometric models to obtain a quasi-continuous network composite material geometric model; S6: Meshing the geometric model of the quasi-continuous mesh composite material obtained in step S5, and applying cooling boundary conditions; inputting material properties, numerically simulating the thermal mismatch behavior of the quasi-continuous mesh composite material during the cooling process, and obtaining the thermal residual stress distribution of the quasi-continuous mesh composite material.

2. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: The geometric parameters of the convex polyhedron reinforcement phase in step S1 include the volume of the convex polyhedron and the radius of the circumscribed circle of the cross section of the XOY plane; the center point of the convex polyhedron reinforcement phase is the origin of the Cartesian coordinate system O(0, 0, 0), and the convex polyhedron reinforcement phase is mirror symmetric with respect to the XOY plane and has an even number of rotational symmetry about the Z axis.

3. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: The number of network plane edges of the mesh structure geometric model in step S2 is not less than 4, the internal angle of the network plane is not less than 90°, and the average aspect ratio of the network plane is not higher than 2:

1.

4. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: The mesh structure parameters in step S2 include model size, number of mesh cells and angle distribution of average angle of network plane.

5. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: The network plane in step S3 accommodates the number N of convex polyhedron enhancement phases i The calculation method is as follows: S31: Calculate the total number N of convex polyhedral reinforcement phases: Where: VF is the volume fraction of the convex polyhedron reinforcement phase; VP is the volume of the convex polyhedron reinforcement phase; L is the model size; S32: Calculate the area ratio sr of the i-th network plane in the mesh structure geometric model i : Where: S i is the area of ​​the ith network plane, S net is the total area of ​​the mesh structure geometric model; S33: Calculate the number of convex polyhedron enhancement phases N accommodated by the i-th network plane i =N×sr i .

6. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: The specific method for calculating the position of the convex polyhedron reinforcement phase in step S4 is as follows: S41: Calculate the center O of the i-th network plane i (X i , Y i , Z i ): Where: ∑V i,j is the node coordinates and NV of the ith network plane i is the number of nodes in the network plane; S42: Calculate a new plane based on the i-th network plane: Extract all the edges of the i-th network plane and point them towards the center O of the network plane. i The length of the radius of the circumscribed circle of the cross section of the XOY plane is translated; the figure enclosed by the translated edges is the new plane Si_new; S43: Generate N in the new plane Si_new i points, and the distance between any two points is not less than the length of the radius of the circumscribed circle of the cross section of the two XOY planes; the generated N i The coordinate positions of the points are taken as the first set Set-Node i , respectively represent the position of the convex polyhedron reinforcement phase in the network plane.

7. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: The specific steps of establishing the geometric model of the quasi-continuous mesh composite material in step S5 are as follows: S51: Calculate the rotation axis Raxis of the convex polyhedral reinforcement phase in the i-th network plane: Raxis=(VN i +Zaxis) / 2 Where: VN i is the normal vector of the ith network plane, and Zaxis is the unit vector in the Z direction of the network plane; S52: With the rotation axis Raxis as the axis, the convex polyhedron reinforcement phase is spatially rotated at a rotation angle of 180° to obtain a new convex polyhedron reinforcement phase Polyhedron_i; S53: According to the first set Set-Node i The coordinate position of each point in the network is used to move the new convex polyhedron reinforcement phase Polyhedron_i from the Cartesian coordinate system origin O(0, 0, 0) and insert the convex polyhedron reinforcement phase into the i-th network plane; S54: Repeat steps S51 to S53, insert convex polyhedral reinforcement phases into all network planes, and gather all convex polyhedral reinforcement phases into the second set REINFORCEMENT to obtain the reinforcement phase geometric model of the composite material; draw a cube with the Cartesian coordinate system origin O (0, 0, 0) and the point (L, L, L) as the minimum and maximum points respectively to obtain the matrix geometric model; assemble the reinforcement phase geometric model and the matrix geometric model of the composite material to obtain a quasi-continuous network composite material geometric model.

8. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: The mesh type in the mesh division described in step S6 is a 4-node tetrahedral unit, and the total number of mesh units is not less than 700,000.

9. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: The cooling boundary conditions in step S6 are set as follows: the high temperature T1 is not greater than 1200°C, the low temperature T0 is not less than -100°C, and the cooling rate ΔT is 80-120°C.

10. The method for predicting thermal residual stress of a quasi-continuous network composite material according to claim 1, characterized in that: In step S6, finite element software ABAQUS is used to perform numerical simulation.

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