MATLAB working condition prediction and ANSYS matching surface creep analysis method

Abstract

The invention relates to a MATLAB working condition prediction and ANSYS matching surface creep analysis method, and belongs to the technical field of mechanical engineering structure connection analysis and monitoring and computer-aided engineering software integration. The method comprises the following steps that a user inputs geometric parameters and typical working conditions through an MATLAB GUIDE interaction interface, and a system can generate a theoretical response curve of the matching surface pressure changing along with the magnitude of interference, the load and the rotating speed in real time and is used for evaluating the maximum allowable working parameter range. And then ANSYS is called to carry out batch finite element simulation, and actual contact pressure distribution and a creep strain cloud picture are obtained, so that the influence of different working condition combinations on the creep behavior of the matching interface is quantified. The method supports visual comparative analysis under the combination of multiple working conditions, and a user can intuitively master the evolution law and the creep development trend of the pressure distribution of the matching surface. The interactive critical failure discrimination module integrated in the system can automatically identify typical contact failure situations and perform significant annotation in images.

Description

Technical Field

[0001] The present invention relates to the technical fields of mechanical connection strength analysis, finite element simulation and human-computer interaction visualization, in particular to a MATLAB working condition prediction and ANSYS mating surface creep analysis method. Background Art

[0002] Interference fit is one of the most common and critical connection methods in rolling bearings, gear couplings, and high-speed rotor systems. Its core mechanism is to artificially create a dimensional difference between the inner ring (or hub) aperture and the main shaft (or journal) outer diameter during the assembly phase, so that the two form a compressed contact in the cold state, thereby providing sufficient normal pressure during operation to suppress relative slip and micro-wear of the mating surfaces. In typical high-speed and heavy-load scenarios such as wind turbine main shafts, aircraft engines, and high-speed machine tools, the mating surfaces are significantly affected by the following coupling factors: (1) Centrifugal expansion: As the speed increases, the inner ring and main shaft produce different degrees of radial expansion, which effectively weakens the initial interference pressure; (2) Thermal expansion: The temperature rise caused by long-term operation further relaxes the fit; (3) Alternating load: Extreme wind conditions or start-stop shocks lead to stress concentration and fatigue accumulation on the mating surfaces; (4) Material creep and relaxation: Under high temperature or high shear conditions, the inner ring undergoes time-dependent plastic flow, continuously reducing the interference.

[0003] However, the existing technical pain points are that the empirical formula for estimating the safe interference margin ignores the coupling between centrifugal force and load, resulting in insufficient or overly conservative safety margins. Engineers need to repeatedly modify the model during single-condition finite element analysis and are unable to traverse the multivariable space within the design window. Isolated alarm logic (threshold comparison) cannot fail based on trend prediction, and alarms that are too early or too late lead to increased maintenance costs. Summary of the Invention

[0004] The purpose of the present invention is to provide a MATLAB working condition prediction and ANSYS mating surface creep analysis method to achieve rapid, intuitive, and traceable visualization of the pressure and creep behavior of the interference fit between bearings and shafts, while simultaneously calculating and analyzing the pressure curve in real time at the front end and automatically identifying the critical failure speed.

[0005] In order to ensure the realization of the above-mentioned invention objectives, the technical solution adopted by the present invention is:

[0006] A MATLAB working condition prediction and ANSYS mating surface creep analysis method includes the following steps:

[0007] Step 1: Use the GUIDE interactive interface designed in MATLAB and enter the geometric parameters, material parameters, preset interference and pre-applied load of the shaft and bearing in the input parameter button;

[0008] Step 2: Invoke elastic contact theory, interference fit model, and centrifugal force correction formula on the MATLAB side to solve the contact pressure distribution on the mating surface in real time and generate theoretical curves showing how pressure changes with different working condition variables.

[0009] Step 3: Load the curve generated in step 2 in real time in the MATLAB GUIDE embedded axes, supporting scaling, rotation, and fast switching between different working conditions. The failure annotation function automatically draws the contact failure critical speed annotation based on the theoretical and simulation curves, that is, predicts the working condition parameter value. When contact failure is detected, a PDF or Excel report of the key annotation data can be output.

[0010] Step 4: Create a sample 3D model and perform ANSYS pre-processing operations;

[0011] Step 5: Write the input parameters in step 1 and the annotated data in step 3 into the ANSYS project in batches, and use Python or ACTAPI to drive the simulation control module to perform the solution to obtain the contact pressure or creep strain results;

[0012] Step 6. After each simulation, call the command to automatically save the contact pressure and creep cloud map as PNG files to obtain the creep trend of different working parameters.

[0013] Specifically, in step 1, the geometric parameters include the bearing inner diameter d, outer diameter D, and width B, and the material parameters include the material elastic modulus E and Poisson's ratio v. These input parameters serve as the basis for step 2. The system automatically calls elastic contact theory, interference fit models, and centrifugal force correction formulas on the MATLAB side to solve the contact pressure distribution on the mating surfaces in real time and generate theoretical curves showing how pressure changes with different operating condition variables. These curves predict the operating condition parameter values, which are used to evaluate the design margin and stress response trend of the structure under given operating conditions.

[0014] Specifically, in step 2, the contact pressure P of the output mating surface is mainly determined by the interference Δd, and the interference is determined by the pre-applied load F. r and the change Δd under the action of the speed ω F and Δd w Pressure P is an important basis for judging whether the mating surface is creeping. Its pressure theory correction formula is as follows:

[0015]

[0016] Δd W =L2-L1

[0017] Δd≈Δd F +Δd W

[0018]

[0019] The bearing inner diameter, outer diameter and inner ring groove bottom diameter are denoted as d, D, and D respectively. G , the bearing width is expressed as B, Cor is the radial static load rating of the bearing, ρ is the material density, the elastic modulus of the shaft and bearing are E1 and E2, the Poisson's ratio of the shaft and bearing are v1 and v2, and L1 and L2 represent the radial deformation of the shaft and the inner ring of the bearing respectively.

[0020] Specifically, in step 3, the failure annotation is implemented by the following MATLAB code to automatically determine the critical speed of contact failure and to mark the graph, which specifically includes the following operation process:

[0021] 1) The current pressure data P is judged. When it is detected that the contact pressure drops to zero (i.e., Pcurrent = 0) and the corresponding speed ω>0, it is determined to be a potential contact failure area;

[0022] 2) Extract the window interval near the failure point and construct a smooth interpolation curve between the original speed and pressure data through the interpolation function;

[0023] 3) Further refine the search on the interpolation curve to obtain the position where the pressure approaches zero with higher precision, and the current speed data is used as the critical failure speed;

[0024] 4) Use the xline function to mark the critical failure position on the current drawing interface and mark the corresponding value;

[0025] 5) At the same time, a prompt box pops up through the beep and warndlg functions to remind the user that there is a risk of contact failure in the current working condition.

[0026] Specifically, in step 4, a sample 3D model is established and ANSYS pre-processing operations are performed, namely, meshing, independence verification, model accuracy verification, etc.

[0027] Specifically, in step 5, the input parameters of step 1 and the annotated data of step 3 are written into the ANSYS engineering model in batches. The boundary conditions, mesh division and load application method are automatically set according to the parameters, and the ANSYS solver is called in sequence through a loop or queue mechanism to obtain the contact pressure distribution and creep strain results under each set of working conditions.

[0028] Specifically, in step 6, after each ANSYS simulation is completed, the contact pressure distribution diagram and creep strain cloud diagram are saved as standard PNG image files; at the same time, the result data can be optionally exported as a structured file to obtain the creep trend of different working parameters for subsequent analysis of the impact of different working parameters on the creep trend.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention has real-time visualization and failure identification capabilities: through MATLAB GUIDE interface interaction and real-time graphics updates, users can intuitively observe the pressure change trend under different loads, speeds and interference fits; at the same time, the integrated failure discrimination module can automatically detect failure characteristics such as zero contact pressure and mark the critical speed, thereby improving the accuracy and automation of failure identification.

[0031] The present invention improves the accuracy and efficiency of interference fit design: it uses elasticity theory and centrifugal correction formulas to quickly obtain theoretical response curves and evaluate structural design margins in advance; it automatically generates analysis reports when preset thresholds are exceeded, reducing the risk of omissions or misjudgments in the design stage.

[0032] The present invention systematically displays the creep evolution trend under multiple working conditions, improves data processing efficiency, and is suitable for batch design and verification under complex working conditions such as high speed and heavy load. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly demonstrate the technical route of the present invention, the relevant drawings are introduced, which constitute a part of this application but do not constitute an improper limitation of the present invention. In the drawings:

[0034] Figure 1 It is a schematic diagram of the process of the present invention;

[0035] Figure 2 This is an example diagram of the interactive interface established by the present invention using MATLAB;

[0036] Figure 3 This is an example diagram of the model 3D and grid division structure of the present invention, where Figure 3 (a) is the 3D diagram of the bearing model. Figure 3 (b) is the mesh planing surface of the bearing outer ring. Figure 3 (c) is the planed surface of the ball mesh. Figure 3 (d) is the mesh planing surface of the bearing inner ring;

[0037] Figure 4 The present invention uses ANSYS simulation conditions to r =15KN, ω=2000r / min, the creep characteristic diagram of the fitting surface when the interference is 0.01mm and 0.025mm respectively;

[0038] Figure 5 The creep characteristic diagram of the mating surface when the radial load is 15000N, 25000N and 35000N respectively under the ANSYS simulation working conditions of Δd=0.01mm and ω=1000r / min is obtained in the present invention;

[0039] Figure 6The working condition of the present invention is Δd=0.025mm, F r = =15KN and the rotation speed is 1000r / min and 2000r / min respectively. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can understand the present invention. It should be understood that the embodiments described are certain embodiments of the present invention, rather than all embodiments. The following detailed description of the embodiments of the present invention provided in the accompanying drawings merely represents selected embodiments of the present invention and is not intended to limit the scope of the invention claimed for protection. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts should fall within the scope of protection of the present invention.

[0041] Example 1: The present invention is implemented by the following technical solutions: Figure 1 As shown, a MATLAB working condition prediction and ANSYS mating surface creep analysis method includes the following steps:

[0042] Step 1: Design the interactive interface in MATLAB, determine the area where each operation button is located, and enter the relevant parameters into the input parameter button.

[0043] This process first designs a graphical interactive interface based on MATLAB's GUIDE or App Designer tool. The interface design follows the modular principle and is divided into areas such as "geometric / material parameter input area", "result output" and "contact pressure, displacement, and effective interference graphic output area" according to function. The user inputs the geometric parameters of the mating shaft and bearing (bearing inner diameter d, outer diameter D and width B), material parameters (elastic modulus E, Poisson's ratio v) and operating conditions (such as preset interference Δd and pre-applied load F) through the interface. r The interface buttons correspond one-to-one with the functional modules, ensuring that users can complete parameter entry and operation control without programming, greatly improving the convenience and accuracy of engineering applications.

[0044] Step 2: Write the corresponding code for the operation buttons on the interactive interface to make it run normally, and determine the operating parameter range to ensure that the mating surface is an interference fit.

[0045] See Figure 2, based on step 1, write a corresponding callback function for each operation button to make it have actual functions. For example, the callback function corresponding to the "Calculate current theoretical pressure" button integrates the elastic contact theory and the centrifugal force correction model, which can calculate the theoretical contact pressure distribution of the mating surface under the current parameters. To ensure that the simulation analysis is always based on reasonable physical boundaries, the system has a built-in parameter verification module. After the user enters the parameters, the program will automatically determine whether the current input meets the basic conditions of "interference fit" (such as the interference amount Δd is positive and the contact pressure P is not less than 0). If not, a prompt will be issued to guide the user to modify the parameter range. This link ensures the physical validity of subsequent modeling and simulation.

[0046] The specific operations of the interactive interface operation buttons are:

[0047] 1) The user enters the required material properties, geometric parameters, etc. in the "Material / Geometric Parameters" input field on the left side of the interface;

[0048] 2) Click the "Calculate" button on the lower left of the interface, and the system will automatically calculate and generate a trend chart showing the contact pressure, radial displacement, and equivalent interference as the working conditions change.

[0049] 3) The key numerical results are displayed synchronously in the upper right corner of the interface, which is convenient for users to view and record in real time;

[0050] 4) The calculated change trend graph is displayed in the lower right corner, and the maximum operating parameter position under the current conditions is automatically marked in the graph to enhance readability and decision-making assistance functions.

[0051] Step 3: Load the curve in step 2 in real time on the interactive interface, and call the failure annotation to obtain the predicted operating condition parameter values.

[0052] The current pressure data P is evaluated. When the contact pressure drops to zero and the corresponding speed ω>0, it is identified as a potential contact failure area. A window interval near the failure point is extracted, and a smooth interpolation curve is constructed between the original speed and pressure data using the interpolation function. The xline function is used to mark the critical failure location and annotate the corresponding value.

[0053] In step 2, the contact pressure P of the output mating surface is mainly determined by the interference Δd, and the interference is determined by the pre-applied load F. r and the change Δd under the action of the speed ω F and Δd w Pressure P is an important basis for judging whether the mating surface is creeping. Its pressure theory correction formula is as follows:

[0054]

[0055] Δd W =L2-L1

[0056] Δd≈Δd F +Δd W

[0057]

[0058] The bearing inner diameter, outer diameter and inner ring groove bottom diameter are denoted as d, D, and D respectively. G , the bearing width is expressed as B, Cor is the radial static load rating of the bearing, ρ is the material density, the elastic modulus of the shaft and bearing are E1 and E2, the Poisson's ratio of the shaft and bearing are v1 and v2, and L1 and L2 represent the radial deformation of the shaft and the inner ring of the bearing respectively.

[0059] Step 4: Create a sample 3D model and perform ANSYS pre-processing (mesh verification, accuracy verification).

[0060] See Figure 3 (ad), after completing the theoretical calculation module on the MATLAB side, the process enters the finite element modeling stage. Based on the aforementioned geometric input parameters, the user uses a deep groove ball 6208 bearing to construct a three-dimensional geometric model of the bearing and shaft interference fit structure in ANSYS. The modeling method can adopt parametric modeling, the automatic modeling function of ANSYS Workbench, or import a constructed CAD model (such as STEP, IGES format) to achieve rapid reconstruction and simulation adaptation of the structure. The specific operations are as follows:

[0061] 1) Material property definition (elastic modulus, Poisson's ratio, etc.);

[0062] 2) Contact pair settings (interference contact, friction type, contact algorithm, etc.);

[0063] 3) Boundary conditions are applied (e.g., fixed end constraints, rotational drive, radial loads);

[0064] 4) Mesh division (control cell mass, size and key parts encryption).

[0065] Taking the analysis shown in Table 1 as an example, by comparing the Hertzian contact pressure results obtained by simulation with the pressure values ​​obtained by the theoretical calculation formula, the maximum relative error is approximately 3.6%. Using the calculation results of the M1 grid scheme as a reference, when the denser M2 grid scheme is adopted, the relative error is reduced to 1.5%, which is better than the coarser M3 grid scheme. Based on a comprehensive consideration of simulation accuracy and computational efficiency, the M2 grid scheme was ultimately selected as the standard calculation configuration for this invention.

[0066] Table 1

[0067]

[0068] As shown in Table 2, by comparing the numerical simulation results of the mating surface contact pressure with the calculated values ​​based on the theoretical formula, the maximum relative error is 1.48%, indicating that the constructed three-dimensional example model has high accuracy in contact response and can effectively reflect the physical behavior under actual working conditions.

[0069] Table 2

[0070]

[0071] Step 5: Based on the operating parameter range obtained from the interactive interface, select example simulation parameters within this range.

[0072] Based on the parameter list generated in batches within the MATLAB interface, users can select representative typical operating conditions for simulation verification in ANSYS, such as those with extreme boundary conditions such as maximum speed, minimum interference, and average load. Parameter selection can be accomplished by automatically invoking the ANSYS API (such as pyansys or ACT scripts) through MATLAB to inject parameters and control simulation tasks. Alternatively, users can manually set simulation plans and execute them in batches.

[0073] In this way, the present invention can verify the consistency between MATLAB calculation and ANSYS simulation on the one hand, and can also quickly obtain representative creep trend images for visual display on the other hand.

[0074] Step 6: Perform creep analysis on the effective model based on the ANSYS transient field to obtain the creep trend of the mating surface under different working conditions.

[0075] After completing parameter injection and simulation task control, the system enters the ANSYS transient structural field analysis phase. In this phase, a creep analysis model is established and a time loading path is applied for representative operating conditions (such as high speed, small interference, and heavy load) specified in the MATLAB interface. A multi-step solution is used to simulate the response behavior of the mating surface under long-term service conditions.

[0076] Different working conditions are set in the ANSYS transient field. The specific operations are as follows:

[0077] 1) When the radial load of the bearing is 15 kN, the speed is 2000 r / min, and the calculation time is 0.15 s, the creep amount of the mating surface is obtained under the working conditions of interference of 0.01 mm and 0.025 mm respectively.

[0078] See Figure 4 The creep amount under the condition of relatively large interference ratio shows a downward trend, which means that under the condition that other working conditions remain unchanged, appropriately increasing the interference ratio can reduce the relative slip between the transmission shaft and the bearing. In order to further explore the relationship between interference ratio and creep amount, in-depth analysis is carried out by adjusting other related parameters.

[0079] 2) With a fixed interference fit of 0.01 mm and ω = 1000 r / min, radial loads of 15 kN, 25 kN, and 35 kN were applied to the inner surface of the bearing inner ring, respectively, with a calculation time of 0.15 s. Transient dynamic simulation analysis was performed for the above three working conditions to determine the creep amount of the mating surface under the three working conditions.

[0080] See Figure 5 As the radial load increases, the slip of the bearing inner ring relative to the shaft continues to increase. This is because as the radial load increases, the contact deformation on the mating surface between the shaft and the inner ring continues to increase, and the gap generated in the opposite direction of the radial load also continues to increase, reducing the anti-creep ability of the bearing inner ring.

[0081] 3) Under the premise of applying a fixed interference of 0.025mm and a radial load of 15kN to the mating surface, the bearing is applied with speeds of 1000r / min and 2000r / min respectively, with a calculation time of 0.15s. Transient dynamic finite element simulation analysis is performed on the above two working conditions, and the creep amount of the mating surface under the two working conditions is obtained.

[0082] See Figure 6 When parameters such as load and interference remain constant, the creep amount decreases as the speed increases from 1000 rpm to 2000 rpm, indicating an inverse relationship between speed and creep. Although speed introduces centrifugal force, its dominant effect on creep is far less than that of load and interference.

[0083] After the simulation is completed, creep response data will be extracted from key areas (such as the center and edge of the fitting surface between the bearing inner ring and the shaft), mainly including:

[0084] 1) Maximum creep strain;

[0085] 2) Radial displacement / deformation;

[0086] 3) contact pressure evolution;

[0087] 4) Relative slip and shear stress changes, etc.

[0088] The extracted results will be exported in the form of structured data, including image files (such as png, tiff), data tables (such as csv, xlsx), and MATLAB files (mat) for easy post-processing.

[0089] Furthermore, the system will construct a three-dimensional response surface of “creep strain-time-operating condition parameters” based on the extracted data to:

[0090] 1) Visually display the creep trend under different boundary conditions;

[0091] 2) Evaluate the impact of specific combined working conditions on the life of the fit;

[0092] 3) Support the development of fault prediction and creep failure warning mechanisms.

[0093] Through this step, the present invention not only achieves efficient coupling of numerical simulation and actual working parameters, but also enhances the visualization and quantitative analysis capabilities of the long-term reliability of the matching structure.

[0094] This method supports visual comparative analysis under multiple operating condition combinations, allowing users to intuitively understand the evolution of pressure distribution and creep trends on mating surfaces. The system's integrated interactive critical failure identification module automatically identifies typical contact failure scenarios (such as limiting speed and equivalent interference exceedance) and prominently annotates them within the image. This feature effectively addresses the lack of clear criteria and ambiguous judgment standards for selecting bearing operating condition parameters in traditional methods, significantly improving the scientific and practical nature of mating structure design and verification.

[0095] The above describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A MATLAB working condition prediction and ANSYS mating surface creep analysis method, characterized in that: The following steps are involved: Step 1: Use the GUIDE interactive interface designed in MATLAB and enter the geometric parameters, material parameters, preset interference and pre-applied load of the shaft and bearing in the input parameter button; Step 2: Invoke elastic contact theory, interference fit model, and centrifugal force correction formula on the MATLAB side to solve the contact pressure distribution on the mating surface in real time and generate theoretical curves showing how pressure changes with different working condition variables. Step 3: Load the curve generated in step 2 in real time in the MATLAB GUIDE embedded axes, supporting scaling, rotation, and fast switching between different working conditions. The failure annotation function automatically draws the contact failure critical speed annotation based on the theoretical and simulation curves, that is, predicts the working condition parameter value. When contact failure is detected, a PDF or Excel report of the key annotation data can be output. Step 4: Create a sample 3D model and perform pre-processing operations for ANSYS simulation analysis; Step 5: Write the input parameters in step 1 and the annotated data in step 3 into the ANSYS project in batches, and use Python or ACTAPI to drive the simulation control module to perform the solution to obtain the contact pressure or creep strain results; Step 6. After the simulation is completed, call the command to automatically save the contact pressure and creep cloud map as a PNG file to obtain the creep trend of different working parameters.

2. A MATLAB working condition prediction and ANSYS mating surface creep analysis method according to claim 1, characterized in that: In step 1, the geometric parameters include the bearing inner diameter d, outer diameter D and width B, and the material parameters include the material elastic modulus E and Poisson's ratio v.

3. The MATLAB working condition prediction and ANSYS mating surface creep analysis method according to claim 1, characterized in that: In step 2, the contact pressure P of the output mating surface is mainly determined by the interference Δd, and the interference is determined by the pre-applied load F. r The changes under the action of the speed ω are Δd F and Δd w , pressure P is an important basis for judging whether the mating surface is creeping, and its pressure theory correction formula is as follows: Δd W =L2-L1 Δd≈Δd F +Δd W The bearing inner diameter, outer diameter and inner ring groove bottom diameter are denoted as d, D, and D respectively. G , the bearing width is expressed as B, Cor is the radial static load rating of the bearing, ρ is the material density, the elastic modulus of the shaft and bearing are E1 and E2, the Poisson's ratio of the shaft and bearing are v1 and v2, and L1 and L2 represent the radial deformation of the shaft and the inner ring of the bearing respectively.

4. The method of MATLAB working condition prediction and ANSYS mating surface creep analysis according to claim 1, characterized in that: In step 3, failure marking is performed by automatically determining the critical speed of contact failure and marking the graph through the following steps: 1) The current pressure data P is judged. When it is detected that the contact pressure drops to zero and the corresponding speed ω>0, it is determined to be a potential contact failure area; 2) Extract the window interval near the failure point and construct a smooth interpolation curve between the original speed and pressure data through the interpolation function; 3) Further refine the search on the interpolation curve to obtain the position where the pressure approaches zero with higher precision, and the current speed data is used as the critical failure speed; 4) Use the xline function to mark the critical failure position on the current drawing interface and mark the corresponding value; 5) At the same time, a prompt box pops up through the beep and warndlg functions to remind the user that there is a risk of contact failure in the current working condition.

5. The method of MATLAB working condition prediction and ANSYS mating surface creep analysis according to claim 1, characterized in that: In step 4, a sample 3D model is created and ANSYS pre-processing operations are performed, namely, meshing, independence verification, and model accuracy verification.

6. The method of MATLAB working condition prediction and ANSYS mating surface creep analysis according to claim 1, characterized in that: In step 5, the input parameters in step 1 and the annotated data in step 3 are written into the ANSYS engineering model in batches. The boundary conditions, mesh division and load application methods are automatically set according to the parameters, and the ANSYS solver is called in sequence through a loop or queue mechanism to obtain the contact pressure distribution and creep strain results under each set of working conditions.

7. The method of MATLAB working condition prediction and ANSYS mating surface creep analysis according to claim 1, characterized in that: In step 6, after each ANSYS simulation, the contact pressure distribution diagram and creep strain cloud diagram are saved as standard PNG image files. At the same time, the result data can be optionally exported as a structured file to obtain the creep trend of different working parameters.

Images