Numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on CEL method

Abstract

The present invention relates to a numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on the CEL method. By means of the ABAQUS software, a geometric component of the thermal spraying substrate is created as a Lagrangian body, and a geometric body component embedded with spherical particles of different particle sizes is created as an Eulerian body. Taking the established geometric components as the research object, material properties are assigned to the spraying substrate and the Eulerian body, and the geometric components are assembled and meshed. A thermo-mechanical coupling analysis is carried out, output variables are defined, the contact properties between the spraying substrate and the powder particles are set, the load conditions of the substrate and the particles are added, the model constraint conditions are added, and the established model is solved and calculated. The calculation results of the model are viewed through the ABAQUS post-processing module. The advantages of the present invention are that based on the ABAQUS software, the process of multi-particle impact on the substrate during AC-HVAF thermal spraying can be truly simulated, and the numerical analysis results of the model can be accurately calculated.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal spraying, and particularly relates to a numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on the CEL method. Background Art

[0002] With the increasing requirements for the service performance of various mechanical equipment under harsh working conditions such as high temperature and corrosive gas environments, it has become particularly important to use surface treatment technologies to improve the surface performance of materials. Thermal spraying technology is an important part of surface engineering and the basis for the development and application of surface engineering technologies. As an emerging thermal spraying process, activated combustion high-velocity air fuel spraying (AC-HVAF) has been increasingly widely used.

[0003] The characteristics of AC-HVAF thermal spraying are that high-speed airflow is generated by the combustion of compressed air and fuel to heat the powder, but the powder is not completely melted, and at the same time, the powder is accelerated to more than 700 m / s and impacts the substrate to form a coating with extremely low oxide content and extremely high density. Especially when preparing nano-coatings, the growth of nano-crystals will occur when traditional supersonic flame spraying equipment sprays nano-powders, resulting in the failure of the coating. However, the flame temperature of activated combustion high-velocity air fuel spraying (AC-HVAF) is low (about 1800 °C) and the particle flight speed is high (up to 700 m / s).

[0004] Particle collision is an important stage in the thermal spraying process. There is energy conversion during the collision of powder particles with the substrate, and the kinetic energy of the particles will be converted into the deformation dissipation energy of the particles and the substrate. Due to the high particle flight speed of AC-HVAF thermal spraying and the extremely short impact time on the substrate (only dozens of nanoseconds), the short process of particle impact on the substrate cannot be directly observed by experimental methods. To make up for the defects of this experimental method and reduce costs, numerical simulation methods are often used for corresponding research. Currently, the common numerical methods in the field of particle impact of supersonic flame spraying are the Lagrangian method based on the material coordinate system and the Eulerian method based on the space coordinate system. When using these two finite element methods to solve large deformation problems, it often leads to abnormal model contact or model mesh distortion. Summary of the Invention

[0005] To overcome the deficiencies of the existing technologies, the objective of the present invention is to provide a numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on the CEL method, accurately and effectively simulating the multi-particle impact process, and calculating the stress-strain distribution, temperature distribution, particle flattening degree, etc. of the particles during the AC-HVAF thermal spraying process. Saving the test cost, shortening the test cycle, and improving the working efficiency of the thermal spraying process. Using the Coupled Eulerian-Lagrangian (CEL) method, by calculating the Euler volume fraction (EVF), tracking the process of the Euler material flowing through the grid.

[0006] To achieve the above objective, the present invention is realized through the following technical solutions:

[0007] A numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on the CEL method, comprising the following steps:

[0008] 1) With the aid of the ABAQUS software, create the geometric component of the thermal spraying substrate as the Lagrangian body, and create the geometric component embedded with spherical particles of different particle sizes as the Eulerian body;

[0009] 2) Taking the geometric components established in step 1) as the research object, assign material properties to the spraying substrate and the Eulerian body; among them, the Johnson-Cook material constitutive equation is selected as the material constitutive model;

[0010] 3) Taking the geometric components established in step 1) as the research object, perform the assembly of the geometric components;

[0011] 4) Taking the geometric model assembled in step 3) as the research object, divide the grids for the Eulerian body and the Lagrangian body;

[0012] 5) Create a Dynamic-Time-Disp-Explicit analysis step to perform thermo-mechanical coupling analysis and define the output variables; the output variables are stress, nodal temperature, element temperature, equivalent plastic strain, and volume fraction within the element;

[0013] 6) Set the contact properties between the spraying substrate and the powder particles

[0014] Add the tangential contact property, normal contact property, and heat generation property of the bonding surface between the powder particles and the spraying substrate. Among them, the tangential contact property of the model is set through the "penalty function" friction formula, the normal contact property is set through surface hard contact, and the penetration behavior between elements is not allowed; the heat generation property is set in the way of energy-consuming heat generation;

[0015] 7) Add the load conditions between the substrate and the particles

[0016] Set a preheating temperature for the spraying substrate and assign temperature and velocity loads to powder particles of different particle sizes;

[0017] 8) Add model constraint conditions

[0018] Establish rigid constraints on the bottom and side surfaces of the spraying substrate and create displacement constraints on the symmetry plane for the Eulerian body;

[0019] 9) Use the ABAQUS / Explicit solver to solve and calculate the established model to obtain the output results of the stress, nodal temperature, element temperature, equivalent plastic strain, and volume fraction within the element defined in step 5);

[0020] 10) View the model calculation results through the ABAQUS post-processing module.

[0021] In step 1), seven types of spherical particles with different particle sizes are assembled inside the Eulerian body.

[0022] In step 6), the tangential contact between the Eulerian body and the Lagrangian body is set as "penalty function" contact, the normal contact is set as hard contact, and the thermal contact is set as the heat generation contact property.

[0023] In step 9), the ABAQUS / Explicit solver is used, and the CEL coupled Euler-Lagrange method is implemented using an explicit integration algorithm, and finally, iterative solution of the numerical model is performed.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The present invention can truly simulate the process of multiple particles impacting the substrate during AC-HVAF thermal spraying, accurately calculate the numerical analysis results of the model, and the specific advantages are:

[0026] 1. The present invention can observe and analyze the dynamic impact process of powder particles and the spraying substrate in real time based on the ABAQUS software. The established thermal spraying multi-particle impact model and calculation results meet the requirements of the thermal spraying process.

[0027] 2. The present invention can more intuitively reflect the stress-strain distribution, temperature distribution, and particle flattening degree of particles during AC-HVAF thermal spraying, which is of great significance in the preparation of high-performance coatings.

[0028] 3. The present invention calculates the porosity of the AC-HVAF thermal spraying coating by using the CEL method through the numerical calculation results of the model.

[0029] 4. The present invention can effectively reveal the particle impact behavior during the AC-HVAF thermal spraying process, provide a theoretical reference for optimizing the spraying process parameters, reduce the time cost during the optimization of the thermal spraying process, improve work efficiency, and achieve a better spraying effect. Description of the Drawings

[0030] Figure 1 is a schematic diagram of the multi-particle impact geometric model for AC-HVAF thermal spraying;

[0031] (a) is a schematic diagram of the assembly; (b) is a schematic diagram of the thermal spraying powder particles.

[0032] Figure 2 is a schematic diagram of the mesh division of the multi-particle impact model for AC-HVAF thermal spraying;

[0033] (a) is a schematic diagram of the assembly mesh; (b) is a schematic diagram of the thermal spraying powder particle mesh.

[0034] Figure 3 is a schematic diagram of the boundary conditions of the multi-particle impact model for AC-HVAF thermal spraying in the present invention;

[0035] (a) is an isometric schematic diagram of the model boundary conditions; (b) is an X-Y plane schematic diagram of the model boundary conditions.

[0036] Figure 4 is an equivalent plastic stress nephogram of the multi-particle impact process for AC-HVAF thermal spraying in the present invention;

[0037] (a) is a nephogram of the matrix stress distribution before particle impact; (b) is a nephogram of the matrix stress distribution during particle impact; (c) is a nephogram of the matrix stress distribution after particle impact).

[0038] Figure 5 is a nodal temperature nephogram of the multi-particle impact process for AC-HVAF thermal spraying;

[0039] (a) is a nephogram of the temperature distribution before particle impact; (b) is a nephogram of the temperature distribution during particle impact; (c) is a nephogram of the temperature distribution after particle impact.

[0040] Figure 6 is an Euler volume fraction pore value nephogram of the multi-particle impact model for AC-HVAF thermal spraying;

[0041] (a) is an Euler volume fraction pore value nephogram before particle impact; (b) is an Euler volume fraction pore value nephogram during particle impact; (c) is an Euler volume fraction pore value nephogram after particle impact.

[0042] Figure 7It is a schematic diagram of the porosity of the coating of the AC-HVAF thermal spraying multi-particle impact model.

[0043] Figure 8 It is a schematic diagram of the sectional porosity of the coating of the AC-HVAF thermal spraying multi-particle impact model. Specific implementation manner

[0044] The present invention will be described in detail below with reference to the accompanying drawings of the specification, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0045] A numerical simulation calculation method for multi-particle impact of AC-HVAF thermal spraying based on the CEL method, based on the ABAQUS software, simulates the finite element numerical values of the processes of spraying particle impact, spreading, deposition, and solidification on the substrate surface, and specifically includes the following steps:

[0046] 1) Establish a geometric component model

[0047] Use the ABAQUS software to establish a geometric dimension model of the AC-HVAF thermal spraying multi-particle impact model, and create a Lagrangian body and an Eulerian body embedded with particles of different particle sizes;

[0048] 2) Taking the geometric components (Lagrangian body, Eulerian body) established in step 1) as the research object, define the material properties of the substrate and the Eulerian body. Considering the transient non-linearity, large deformation, and large strain rate characteristics of the spraying particle impact behavior, select the Johnson-Cook material constitutive equation, and assign material properties to the substrate and the Eulerian body respectively. Among them, the fluid materials in the Eulerian body can include multiple materials (such as WC-12Co powder particles and WC-10Co-4Cr powder particles in a molten state and a semi-molten state);

[0049] 3) Taking the geometric components established in step 1) as the research object, perform the assembly of the geometric components

[0050] Assemble the Eulerian body directly above the Lagrangian body, and the two are in contact, as shown in Figure 1 ;

[0051] 4) Taking the geometric model assembled in step 3) as the research object, divide the meshes for the Eulerian body and the Lagrangian body, as shown in Figure 2 .

[0052] First, divide the meshes for the Lagrangian body: the overall mesh element size is 5um, the mesh element type is EC3D8RT, and the hourglass control adopts enhanced settings. Then, divide the meshes for the Eulerian body: the overall mesh element size is 1.5um, the mesh element type is EC3D8R, and the hourglass control adopts the default settings.

[0053] 5) Create a Dynamic-Time-Disp-Explicit analysis step for thermo-mechanical coupling analysis, and define the output variables S, Mises (von Mises stress), NT11 (nodal temperature), TEMP (element temperature), PEEQ (equivalent plastic strain), and EVF (representing the volume fraction within the element for visualizing the fluid).

[0054] 6) Create interactions for the model

[0055] Set the contact conditions between the matrix and the particles, and add tangential contact, normal contact, and thermal contact to the bonding surface between the particles and the matrix to ensure effective bonding between the two (the bonding mode between the particles and the matrix surface is mainly mechanical bonding, and there may also be metallurgical bonding due to material melting on the matrix material with a relatively low melting point. Whether it is fitting, overlapping, or there is a common part).

[0056] 7) Add load conditions for the matrix and the particles

[0057] Set the preheating temperature of 600K for the sprayed matrix, and assign temperature and velocity loads to powder particles with different particle sizes;

[0058] 8) Add model constraint conditions.

[0059] Establish rigid constraints on the bottom and side surfaces of the sprayed matrix, and create displacement constraints on the symmetry plane for the Eulerian body;

[0060] 9) Use the ABAQUS / Explicit solver to solve the established model and obtain relevant output results: stress (see Figure 4 ), nodal temperature (see Figure 5 ), and Eulerian volume fraction pore value (see Figure 6 ).

[0061] 10) View the model calculation results through post-processing

[0062] Due to the use of Eulerian elements, the visualization of the results requires the aid of the tool viewcut.

[0063] Example

[0064] A numerical simulation calculation method for multi-particle impact in AC-HVAF thermal spraying based on the CEL method includes the following steps:

[0065] 1) Use ABAQUS software to establish a geometric dimension model of the AC-HVAF thermal spraying multi-particle impact model, and create Lagrangian bodies and Eulerian bodies embedded with particles of different particle sizes;

[0066] 2) Create the material properties of the model. Add the created material properties of TC18 titanium alloy and WC-12Co to the matrix component and particle component in the multi-particle impact model respectively from the material library. The density of WC-12Co particles is 14320 kg / m 3 , and the specific heat capacity is 295 J·kg -1 / K, the solidus temperature is 1610 K, and the liquidus temperature is 1680 K. The plastic properties of the two materials adopt the J-C constitutive model built in ABAQUS.

[0067] 3) Take the geometric component established in step 1) as the research object, perform the assembly of the geometric component, and assemble the Euler domain directly above the Lagrangian body;

[0068] 4) Take the geometric component assembled in step 3) as the research object, and mesh the geometric component and the assembly

[0069] First, mesh the Lagrangian body: the overall seed size is 5 μm, the mesh element type is EC3D8RT, and the hourglass control adopts enhanced settings. Then mesh the Euler body: the overall seed size is 1.5 μm, the mesh element type is EC3D8R, and the hourglass control adopts the default settings.

[0070] 5) Create a Dynamic-Time-Disp-Explicit analysis step for thermo-mechanical coupling analysis, and define the output variables S, Mises (von Mises stress), NT11 (node temperature), TEMP (element temperature), PEEQ (equivalent plastic strain), EVF (representing the volume fraction within the element, used for visualizing the fluid);

[0071] 6) Set the interaction properties during the multi-particle impact process

[0072] Set the tangential contact between the Euler material and the Lagrangian material as "penalty function" contact, the normal contact as hard contact, and additionally add the heat generation contact property;

[0073] 7) Add the load conditions of the matrix and the particles

[0074] Set the preheating temperature of 600 K for the spraying matrix through predefined fields, and assign temperature (temperature range: 1390 - 1485 K) and velocity (velocity range: 420 - 645 m / s) loads to powder particles of different particle sizes;

[0075] 8) Add the model constraint conditions

[0076] Establish a rigid constraint with the bottom and side surfaces of the spraying matrix completely fixed, and create a displacement constraint on the symmetry plane for the Euler body;

[0077] 9) Use the ABAQUS / Explicit solver to solve the established model and obtain output results such as stress, nodal temperature, element temperature, equivalent plastic strain, etc.;

[0078] 10) View the model calculation results through post-processing. Since Eulerian elements are used, the visualization of the results requires the aid of the tool viewcut.

Claims

1. A numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on the CEL method, characterized in that It includes the following steps: 1) Create a geometric component of the thermal spraying substrate as a Lagrangian body with the help of ABAQUS software, and create a geometric component embedded with spherical particles of different particle sizes as an Eulerian body; 2) Take the geometric components established in step 1) as the research object, and assign material properties to the spraying substrate and the Eulerian body; among them, the Johnson-Cook material constitutive equation is selected as the material constitutive model; 3) Take the geometric components established in step 1) as the research object, and perform the assembly of the geometric components; 4) Take the geometric model assembled in step 3) as the research object, and divide the meshes for the Eulerian body and the Lagrangian body; 5) Create a Dynamic-Time-Disp-Explicit analysis step to perform thermo-mechanical coupling analysis and define the output variables; the output variables are stress, nodal temperature, element temperature, equivalent plastic strain, and volume fraction within the element; 6) Set the contact properties between the spraying substrate and the powder particles Add the tangential contact property, normal contact property, and heat generation property of the interface between the powder particles and the spraying substrate. Among them, the tangential contact property of the model is set through the "penalty function" friction formula, the normal contact property is set through surface hard contact, and penetration behavior between elements is not allowed; the heat generation property is set in the way of energy-consuming heat generation; 7) Add the load conditions of the substrate and the particles Set the preheating temperature for the spraying substrate, and assign temperature and velocity loads to the powder particles of different particle sizes; 8) Add the model constraint conditions Establish rigid constraints on the bottom surface and side surfaces of the spraying substrate, and create displacement constraints on the symmetry plane for the Eulerian body; (9) Use the ABAQUS / Explicit solver to solve and calculate the established model to obtain the output results of the stress, nodal temperature, element temperature, equivalent plastic strain, and volume fraction within the element defined in step 5); 10) View the model calculation results through the ABAQUS post-processing module.

2. A numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on the CEL method according to claim 1, characterized in that, In step 1), spherical particles of 7 different particle sizes are assembled inside the Eulerian body.

3. A numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on the CEL method according to claim 1, characterized in that, In step 6), the tangential contact between the Eulerian body and the Lagrangian body is set as "penalty function" contact, the normal contact is set as hard contact, and the thermal contact is set as heat generation contact property.

4. A numerical calculation method for multi-particle impact of AC-HVAF thermal spraying powder based on the CEL method according to claim 1, characterized in that, In step 9), the ABAQUS / Explicit solver is used, and the CEL coupled Euler-Lagrange method is implemented using the explicit integration algorithm, and finally the iterative solution of the numerical model is carried out.

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