Ansys-based brake disc thermal-structural coupling analysis method

Abstract

The application discloses an Ansys thermal-solid coupling analysis method for a brake disc based on Spaceclaim, relates to the technical field of brake disc thermal-solid coupling simulation, and aims at solving the problems of complex working conditions, large calculation amount and inconvenient operation of the existing thermal-solid coupling analysis method for a racing brake disc. The technical points of the application include the following steps: step one, establishing a brake disc and a friction plate model, importing the brake disc and the friction plate model into a finite element analysis software Ansys, selecting materials for the brake disc and the friction plate and inputting material properties, and setting a step number and a time; step two, applying boundary conditions, regarding the braking force as a linear process, and applying the braking force; step three, repairing a distorted grid; step four, defining a contact surface as friction, formulating a generalized Lagrange method, updating stiffness for each iteration, and performing program control on the rest, setting a connection mode as a geometric body-ground, and setting a type as rotation; and step five, obtaining temperature distribution and deformation through thermal-solid coupling analysis.

Description

Technical Field

[0001] This invention relates to the field of brake disc thermo-mechanical coupling simulation technology, and more specifically, to a brake disc thermo-mechanical coupling analysis method based on Ansys. Background Technology

[0002] In motorsports, braking systems frequently endure high-intensity braking loads, leading to a rapid increase in brake disc temperature and thermal fade, manifested as a decrease in the coefficient of friction and a reduction in braking force, seriously threatening track safety. Studies show that approximately 90% of kinetic energy is converted into heat during braking. Insufficient heat dissipation or uneven temperature distribution exacerbates thermal stress and deformation, potentially causing thermal cracks and structural failure. Therefore, accurately predicting the temperature field and heat power distribution of brake discs under actual operating conditions is a core prerequisite for optimizing material selection, structural design, and heat dissipation performance. Although some studies have improved the thermal fatigue life of brake discs by improving materials (such as high thermal conductivity alloys) or optimizing structures (such as ventilation slot design), the verification of these effects still relies on time-consuming and costly bench tests, lacking efficient and accurate digital design tools.

[0003] Currently, thermo-mechanical coupling technology, as a key means of analyzing thermo-mechanical interactions, has been widely applied in the field of brake disc simulation. Traditional methods require simultaneous coupling of thermodynamic and mechanical models, iteratively solving for the interaction between temperature and stress fields, resulting in high computational complexity and resource consumption. For example, under emergency braking conditions, the surface temperature of the brake disc can instantaneously exceed 700°C, requiring the handling of nonlinear material properties and boundary conditions in transient analysis, further increasing the computational difficulty. In addition, existing simulation processes require highly skilled operators and are difficult to respond quickly to the dynamic design requirements of racing car braking systems, such as lightweight design and high-temperature resistance. Therefore, there is an urgent need to develop a method that simplifies the thermo-mechanical coupling process and reduces computational complexity to improve brake disc design efficiency and ensure the braking stability and safety of racing cars under extreme conditions.

[0004] In motorsports, brake fade due to overheating of brake discs is a frequent occurrence. Therefore, studying the actual operating temperature and thermal power of brake discs in vehicles is increasingly important for improving the shape and materials of racing brake discs in the design process, thus preventing serious braking system problems caused by brake fade on the track. Thermo-mechanical coupling technology is widely used in thermodynamic simulations; however, existing thermo-mechanical coupling methods require coupled analysis of mechanics and heat, often resulting in complex operating conditions, large computational loads, and difficulties in implementation. Summary of the Invention

[0005] The technical problem to be solved by this invention is:

[0006] Existing thermo-mechanical coupling analysis methods for racing car brake discs are complex, computationally intensive, and difficult to operate.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0008] This invention provides a thermo-mechanical coupling analysis method for brake discs based on Ansys, comprising the following steps:

[0009] Step 1: Material Properties and Step Size Settings: Create brake disc and friction pad models, import the brake disc and friction pad models into the finite element analysis software Ansys, select materials for the brake disc and friction pad and input material properties, and set the number of steps and time.

[0010] Step 2, Boundary Conditions and Loading: Apply boundary conditions, treating the braking force as a linear process, and apply braking force;

[0011] Step 3: Distorted mesh repair;

[0012] Step 4, Analysis Settings: Define the contact surface as friction, formulate it as the generalized Lagrange method, update the stiffness in each iteration, and control the rest by the program. Set the connection method to geometry-ground and the type to rotation.

[0013] Step 5, Analysis Results: Temperature distribution and deformation were obtained through thermo-mechanical coupling analysis.

[0014] Furthermore, the brake disc described in step 1 is made of 2Cr13 martensitic stainless steel.

[0015] Furthermore, the material properties mentioned in step one include: Young's modulus, Poisson's ratio, coefficient of thermal expansion, specific heat capacity, and isotropic thermal conductivity.

[0016] Furthermore, in step two, boundary conditions are applied using the convective heat transfer coefficient and thermal power.

[0017] Furthermore, the method for calculating the convective heat transfer coefficient α is as follows:

[0018]

[0019] In the formula, u∞ is the airflow velocity (m / s); L is the wall length (m); u is the kinematic viscosity of air (m° / s); P r λ is the Prandtl number; a The thermal conductivity of air is [W / (m·K);

[0020] Taking the speed of the race car as approximately equal to the airflow velocity u∞, the convective heat transfer coefficient is calculated.

[0021] Furthermore, in step two, the power of kinetic energy is considered to be entirely converted into heat power P:

[0022] P=FV

[0023] Where F represents braking force and V represents vehicle speed.

[0024] Furthermore, the distortion mesh repair described in step three specifically involves using the Spaceclaim module to repair the distortion mesh generated by the file conversion.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] This invention employs coupled-field transient analysis using thermal power and convective heat transfer coefficient, saving time and cost while reducing experimental risks. It simplifies operating conditions, improving simulation efficiency and shortening simulation time while ensuring simulation quality, offering strong operability. Through thermo-mechanical coupling technology, this invention accurately simulates the temperature distribution of the brake disc during braking, helping to identify high-temperature regions and prevent thermal damage. By simultaneously analyzing thermal and mechanical stresses through stress and deformation prediction, it predicts the thermal deformation and stress distribution of the brake disc, assessing its structural integrity.

[0027] The simulation results of this invention can be used to improve the design of brake discs, such as optimizing the heat dissipation structure and geometry, and improving heat dissipation efficiency and braking performance. Attached Figure Description

[0028] Figure 1 This is a mesh quality distribution diagram in an embodiment of the present invention;

[0029] Figure 2 These are the reference geometry view and the moving geometry view in the embodiments of the present invention;

[0030] Figure 3 The front brake disc convergence curves in this embodiment of the invention are shown below, where (a) is the front brake disc force convergence curve, (b) is the front brake disc displacement convergence curve, and (c) is the front brake disc thermal convergence curve.

[0031] Figure 4 The following are the rear brake disc convergence curves in the embodiments of the present invention, wherein (a) is the rear brake disc force convergence curve, (b) is the rear brake disc displacement convergence curve, and (c) is the rear brake disc thermal convergence curve.

[0032] Figure 5 The following are simulation results of the brake disc in the embodiments of the present invention: (a) stress diagram of the front brake disc, (b) stress diagram of the rear brake disc, (c) temperature distribution diagram of the front brake disc, and (d) temperature distribution diagram of the rear brake disc.

[0033] Figure 6 The following are temperature distribution diagrams of the front brake disc in an embodiment of the present invention: (a) is the temperature distribution diagram of the front brake disc under high avoidance conditions, and (b) is the temperature distribution diagram of the front brake disc under durability conditions.

[0034] Figure 7The following is a temperature distribution cloud map of the rear brake disc in an embodiment of the present invention, wherein (a) is a temperature distribution map of the rear brake disc under high avoidance conditions, and (b) is a temperature distribution map of the rear brake disc under durability conditions.

[0035] Figure 8 These are measured images of the temperature sensor in an embodiment of the present invention;

[0036] Figure 9 This is a diagram of thermal analysis material parameters in an embodiment of the present invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, exemplary embodiments or examples of the invention will be described below in conjunction with the accompanying drawings. Obviously, the described embodiments or examples are merely some, not all, of the embodiments or examples of the present invention. All other embodiments or examples obtained by those skilled in the art based on the embodiments or examples of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0038] 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.

[0039] Example 1

[0040] Ansys-based indirect thermo-mechanical coupling analysis method for brake discs includes:

[0041] Material properties and step size settings: Create brake disc and friction plate models, import the brake disc and friction plate models into the finite element analysis software Ansys, select materials for the brake disc and friction plate and input material properties, and set the number of steps and time.

[0042] Create solid models of the brake disc and friction pads. Select 2Cr13 martensitic stainless steel as the brake disc material due to its good heat resistance, and input its material properties into the material library, such as... Figure 9 As shown, it includes Young's modulus, Poisson's ratio, coefficient of thermal expansion, specific heat capacity, and isotropic thermal conductivity.

[0043] The number of steps and time are determined in the transient analysis module; for the step length setting, the tracks of the 2022-2023 China University Formula Student Racing Championship are selected for analysis, including high avoidance tracks and endurance tracks.

[0044] Boundary conditions and load application: Boundary conditions are applied using the convective heat transfer coefficient and thermal power, and the force generated by braking is treated as a linear process, and braking force is applied.

[0045] Many factors influence the heat transfer coefficient, including fluid flow state, fluid physical properties, wall temperature and geometry, temperature difference, and phase change. Considering the relatively enclosed position of the brake disc, the latter two can be ignored. Since the convective heat transfer coefficient is directly proportional to vehicle speed, and decreases approximately linearly with speed, the calculation method for the convective heat transfer coefficient is as follows:

[0046]

[0047] In the formula, u∞ is the airflow velocity (m / s); L is the wall length (m); u is the kinematic viscosity of air (m° / s); P r λ is the Prandtl number; a The thermal conductivity of air is [W / (m·K)].

[0048] Ignoring the influence of air temperature changes around the brake disc, and to simplify calculations, the race car speed is approximated to the airflow velocity u∞. The convective heat transfer coefficient is calculated, as shown in Table 1. The calculated convective heat transfer coefficient at a speed of 16 m / s is... .

[0049] Table 1

[0050]

[0051] Since the algorithm that all kinetic energy is converted into heat generated by friction of the brake disc has a large error during wheel braking, it is approximated that all the power of kinetic energy is converted into heat power:

[0052] P=FV

[0053] As shown in Table 2, the calculated thermal power is 705.44 W.

[0054] Table 2

[0055]

[0056] Apply braking force.

[0057] Distorted Mesh Repair: Use the Spaceclaim module to repair distorted meshes caused by file conversion.

[0058] This invention uses thermal power and convective heat transfer coefficient for coupled field transient analysis. Due to the distorted mesh generated during the conversion between CAT.file and Stp.file, the Spaceclaim module's repair module is used to repair the distorted mesh. Although virtual topology can also solve the distorted mesh generated during the conversion between CAT.file and Stp.file, it cannot solve the problem of the minimum element mesh quality being too small.

[0059] Analysis Setup: In the contact module, all contact surfaces are defined as friction, with a friction coefficient of 0.157. The formula is generalized using the generalized Lagrangian method. Stiffness is updated for each iteration. The detection method, penetration tolerance, elastic sliding tolerance, and heat conduction are all program-controlled. A connection method is inserted in the connection pair, set to geometry-ground, with a rotational type. The reference geometry view and the moving geometry view are obtained as follows: Figure 2 As shown.

[0060] Regarding the constraint analysis settings, this invention, while ensuring convergence, makes the constraint conditions as close as possible to the actual working conditions. Based on a high-quality mesh, time integration is enabled according to time, with 0.0001s as the minimum time step and 0.0002s as the maximum time step.

[0061] Analysis results: such as Figures 6-7 As shown, the theoretical maximum temperature of the 24C front brake disc analysis is 4.5% lower than that of the 23C in high-avoidance tracks and 11.1% lower than that of the 23C in endurance tracks. The maximum temperature of the front wheel in high-avoidance tracks is 93.977℃, and the maximum temperature in endurance tracks is 182.05℃. The maximum temperature of the rear wheel in high-avoidance tracks is 71.378℃, and the maximum temperature in endurance tracks is 184.12℃.

[0062] Example 2

[0063] Ansys-based direct thermo-mechanical coupling analysis method for brake discs includes:

[0064] Material properties and step size settings: Create brake disc and friction plate models, import the brake disc and friction plate models into the finite element analysis software Ansys, select materials for the brake disc and friction plate and input material properties, and set the number of steps and time.

[0065] Establish solid models of the brake disc and friction pads. Select 2Cr13 martensitic stainless steel as the brake disc material with good heat resistance and input its material properties into the material library, including Young's modulus, Poisson's ratio, coefficient of thermal expansion, specific heat capacity, and isotropic thermal conductivity.

[0066] The number of steps and time are determined in the transient analysis module; for the step length setting, the track of the 2022-2023 China University Formula Student Racing Championship is selected for analysis.

[0067] Boundary conditions and load application: Boundary conditions are applied using the convective heat transfer coefficient and thermal power, and the force generated by braking is treated as a linear process, and braking force is applied.

[0068] Many factors influence the heat transfer coefficient, including fluid flow state, fluid physical properties, wall temperature and geometry, temperature difference, and phase change. Considering the relatively enclosed position of the brake disc, the latter two can be ignored. Since the convective heat transfer coefficient is directly proportional to vehicle speed, and decreases approximately linearly with speed, the calculation method for the convective heat transfer coefficient is as follows:

[0069]

[0070] In the formula, u∞ is the airflow velocity (m / s); L is the wall length (m); u is the kinematic viscosity of air (m° / s); P r λ is the Prandtl number; a The thermal conductivity of air is [W / (m·K)].

[0071] Ignoring the influence of air temperature changes around the brake disc, and to simplify calculations, the race car speed is approximated to the airflow velocity u∞. The convective heat transfer coefficient is calculated, as shown in Table 1. The calculated convective heat transfer coefficient at a speed of 16 m / s is... .

[0072] Table 1

[0073]

[0074] Since the algorithm that all kinetic energy is converted into heat generated by friction of the brake disc has a large error during wheel braking, it is approximated that all the power of kinetic energy is converted into heat power:

[0075] P=FV

[0076] As shown in Table 2, the calculated thermal power is 705.44 W.

[0077] Table 2

[0078]

[0079] The applied braking force is 0.

[0080] Distorted Mesh Repair: Use the Spaceclaim module to repair distorted meshes caused by file conversion.

[0081] This invention uses thermal power and convective heat transfer coefficient for coupled field transient analysis. Due to mesh distortion caused by the conversion between CAT.file and Stp.file, the Spaceclaim module's repair module is used to repair the distorted mesh. Although virtual topology can also resolve mesh distortion caused by the conversion between CAT.file and Stp.file, it cannot solve the problem of excessively small minimum element mesh quality. Figure 1As shown, the average mesh quality of the repaired front brake disc is 0.78864, and that of the rear brake disc is 0.87705, compared to the track of the 2022-2023 China University Formula One Racing Championship.

[0082] The method of optimizing mesh quality using virtual topology significantly improves the results, providing a solid foundation for the convergence speed and performance of subsequent thermo-mechanical coupling analysis.

[0083] like Figures 3-4 As shown, the front brake disc force convergence curve, front brake disc displacement convergence curve, front brake disc thermal convergence curve, rear brake disc force convergence curve, rear brake disc displacement convergence curve, and rear brake disc thermal convergence curve all exhibit good convergence effects.

[0084] Analysis results: such as Figure 5 As shown, the temperature distribution and deformation were obtained through thermo-mechanical coupling analysis. Under the conditions of brake oil pressure of 6 MPa for the front brake disc and 4 MPa for the rear brake disc, and a friction coefficient of 0.157, the maximum deformation of the front brake disc was 0.26244 mm and the highest temperature of the brake disc in a short time was 88.299℃ in the instant of braking, within approximately 0.03 seconds. The maximum deformation of the rear brake disc was 0.18861 mm and the highest temperature of the brake disc in a short time was 40.221℃.

[0085] Compared with the indirect analysis method in Example 1, the direct analysis method in Example 2 has the following advantages: ① In the transient dynamics module, the actual rotation of the brake disc can be simulated, including the friction pads pressing against the brake disc, and the brake disc being decelerated until the rotational speed reaches 0. ② By applying a command flow, the heat generated by the brake disc during operation can be analyzed, which is more valuable than the temperature analyzed by the indirect method.

[0086] like Figure 8 As shown, an infrared non-contact temperature sensor is used to monitor the brake disc temperature, which is transmitted wirelessly to a data acquisition platform for real-time, high-precision, non-contact measurement. Monitoring revealed that the actual maximum temperature of the brake disc during endurance running was close to 170°C, and approximately 60°C per lap on a high-altitude track, which is largely consistent with the thermo-mechanical coupling analysis results of this embodiment.

[0087] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A thermo-mechanical coupling analysis method for brake discs based on Ansys, characterized in that, The steps include the following: Step 1: Material Properties and Step Size Settings: Create brake disc and friction pad models, import the brake disc and friction pad models into the finite element analysis software Ansys, select materials for the brake disc and friction pads and input material properties, and set the number of steps and time. Step 2, Boundary Conditions and Loading: Apply boundary conditions, treating the braking force as a linear process, and apply braking force; Step 3: Distorted mesh repair; Step 4, Analysis Settings: Define the contact surface as friction, formulate it as the generalized Lagrange method, update the stiffness in each iteration, and control the rest by the program. Set the connection method to geometry-ground and the type to rotation. Step 5: Analysis Results: Temperature distribution and deformation were obtained through thermo-mechanical coupling analysis; The brake disc mentioned in step one is made of 2Cr13 martensitic stainless steel. The material properties mentioned in step one include: Young's modulus, Poisson's ratio, coefficient of thermal expansion, specific heat capacity, and isotropic thermal conductivity; In step two, boundary conditions are applied using the convective heat transfer coefficient and thermal power. The method for calculating the convective heat transfer coefficient α is as follows: In the formula, u ∞ L is the airflow velocity, in m / s; L is the wall length, in m; v is the kinematic viscosity of air, in m³ / s. 2 / s;P r λ is the Prandtl number; a is the thermal conductivity of air, with units of W / (m·K). Take the speed of the race car as approximating the speed of the airflow u ∞ The convective heat transfer coefficient is calculated.

2. The brake disc thermo-mechanical coupling analysis method based on Ansys according to claim 1, characterized in that, In step two, the power of kinetic energy is considered to be entirely converted into heat power P: P=FV Where F represents braking force and V represents vehicle speed.

3. The brake disc thermo-mechanical coupling analysis method based on Ansys according to claim 2, characterized in that, The distorted mesh repair described in step three specifically involves using the SpaceClaim module to repair the distorted mesh generated by file conversion.

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