Gear contact fatigue life evaluation method and system considering multi-stress coupling

Abstract

The invention relates to the technical field of gear life evaluation, in particular to a gear contact fatigue life evaluation method and system considering multi-stress coupling. The method comprises the following steps: S1, constructing a gear three-dimensional geometric model according to gear geometric parameters to be evaluated; s2, constructing a gear thermal analysis model based on the gear three-dimensional geometric model; s3, constructing a gear contact analysis model based on the gear thermal analysis model, and calculating to obtain gear tooth surface contact stress; s4, based on a Dang Van multi-axial fatigue criterion, introducing a residual stress correction term, and constructing a gear contact fatigue life evaluation model; and S5, on the basis of the relevant actual working condition data of the gear, calculating the contact fatigue life of the gear according to the gear contact fatigue life evaluation model. Deep fusion evaluation of multiple stresses of the tooth surface contact stress, the thermal stress and the residual stress is realized, and a guidance basis is provided for evaluating and prolonging the service life of the gear.

Description

Technical Field

[0001] The present invention relates to the technical field of gear life assessment, and in particular to a gear contact fatigue life assessment method considering multi-stress coupling. Background Art

[0002] In the existing technology, the calculation methods of gear contact fatigue life all involve the analysis of the stress field on the tooth surface. Residual stress will be generated during the processing of gears, and thermal stress will be generated due to frictional heat during the meshing process. However, the prediction of gear contact fatigue life mostly only considers the tooth surface contact stress, or considers the pairwise coupling of tooth surface contact stress and thermal stress, and tooth surface contact stress and residual stress. In actual working conditions, the operation of gears is usually under complex loads where tooth surface contact stress, thermal stress and residual stress coexist. Both thermal stress and residual stress will significantly affect the mechanical properties and fatigue life of gears, resulting in inaccurate calculation results of tooth surface contact fatigue life under complex loads. Summary of the Invention

[0003] (1) Technical issues to be resolved The main purpose of the present invention is to provide a gear contact fatigue life assessment method, system and medium considering multi-stress coupling, which is conducive to solving the problem of poor accuracy of tooth surface contact fatigue life calculation results under complex loads.

[0004] (2) Technical solution In order to achieve the above object, the present invention provides a gear contact fatigue life assessment method considering multiple stress coupling, comprising the steps of: S1, constructing a three-dimensional geometric model of the gear according to the geometric parameters of the gear to be evaluated; S2, constructing a gear thermal analysis model based on the gear three-dimensional geometric model, including: S21, importing the gear three-dimensional geometric model into finite element software, performing structural mesh division, performing local mesh encryption in the tooth surface contact area and the tooth root working area, and performing mesh coarsening processing in the remaining areas; S22, based on the actual situation of the gear, defining the gear-related material properties, specifying the thermophysical parameters, and establishing a steady-state heat transfer analysis step; S23, dividing the convective heat transfer scenarios according to the operating environment of the gear, and calculating the convective heat transfer coefficient of the tooth surface, the convective heat transfer coefficient of the end face, and the convective heat transfer coefficient of the tooth top respectively; S24, calculate the friction heat flow of the gear meshing surface; S25, loading the calculation results of step S23 and step S24 into the gear three-dimensional geometric model to construct the gear thermal analysis model; S3, based on the gear thermal analysis model, constructing a gear contact analysis model to calculate the gear tooth surface contact stress, including: S31, defining the contact type and boundary conditions; based on the meshing relationship of the gear pair, determining the contact surface of the first gear as the active surface and the contact surface of the second gear as the passive surface, thereby establishing a surface-to-surface contact pair; and setting appropriate boundary conditions to simulate actual working conditions; S32, applying a load: applying a load to the structural field model based on the actual working condition, wherein the calculation result of the gear thermal analysis model is defined as a temperature load applied to the structural field model; S33, based on the step S31 and the step S32, constructing a gear contact analysis model; calculating the gear tooth surface contact stress distribution for evaluating the fatigue life of subsequent gears; S4, based on the Dang Van multiaxial fatigue criterion, introduces the residual stress correction term to construct a gear contact fatigue life assessment model: in, represents the maximum shear stress amplitude, represents the hydrostatic stress, represents the material parameters, represents the residual stress, represents the fatigue strength coefficient under pure torsion loading, represents the fatigue strength index under pure torsion loading, Indicates contact fatigue life; S5, calculating the gear contact fatigue life based on the gear-related actual working condition data and the gear contact fatigue life assessment model.

[0005] Preferably, the step S1 further includes, S11 simplification of the model: constructing a three-dimensional geometric model of the gear of the meshing part based on the symmetry of the gear.

[0006] Preferably, the gear is a spur gear or a helical gear.

[0007] Preferably, the boundary condition setting in step S31 includes the steps of: S311, establishing a rigid reference point coupling constraint model: randomly selecting a point on the rotation axis of the first gear and the second gear to establish a rigid reference point, and constructing a coupling constraint model between the inner hole surface of the gear hub and the corresponding reference point; S312, setting the analysis steps and boundary conditions for contact analysis: Based on the finite element analysis software, create the initial contact setting analysis step, the torque application analysis step, and the speed application meshing transmission analysis step in a sequential order to simulate the contact and transmission process of the gears in stages; The initial contact setting analysis step includes: fixing all degrees of freedom of the first gear, applying a small rotational displacement to the axis degree of freedom of the second gear, causing the tooth surface of the first gear to contact the tooth surface of the second gear, and establishing an initial contact state; The torque application analysis step includes: releasing the rotational freedom of the second gear around its axis and applying torque to the second gear; The step of applying a rotational speed to realize meshing transmission analysis includes: applying a certain rotational speed on the axis of the first gear to realize meshing transmission of the gears; S313, defining the application object of the boundary condition: applying the torque to the reference point of the second gear, and applying the rotation angle corresponding to the rotation speed to the reference point of the first gear.

[0008] Preferably, the residual stress data in step S4 is obtained by testing the residual stress of the tooth surface.

[0009] Preferably, the fatigue strength coefficient under pure torsional loading in step S4 is The fatigue strength index under pure torsion loading The fatigue strength coefficient under pure torsional loading is obtained by performing a pure torsional fatigue test on a fatigue testing machine; applying a pure torsional load to a standard specimen of the gear material and recording the fatigue life of the specimen under different load levels; performing statistical analysis on the test data and fitting the fatigue life curve using a mathematical model. The fatigue strength index under pure torsion loading The value of .

[0010] Preferably, in step S23, Convection heat transfer coefficient of the tooth surface include: in, represents the angular velocity, represents the thermal conductivity, Indicates the density of the lubricating oil, represents the specific heat capacity of the lubricating oil, Indicates the kinematic viscosity of the lubricating oil, represents the thermal diffusivity, , Indicates the tooth height at the meshing point, represents the radius of the meshing point, represents the normalized total cooling capacity; The convective heat transfer coefficient of the end surface includes the convective heat transfer coefficient of the end surface in three flow states: laminar flow state, transitional laminar flow state, and turbulent flow state; wherein, The laminar flow state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the lubricating oil Prandtl number, , represents the Reynolds number, , m represents the exponential constant, represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear; The transition laminar state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the thermal conductivity of the lubricating oil, represents the characteristic speed of the gear, represents the characteristic length of the gear; The turbulent state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the lubricating oil Prandtl number, , represents the Reynolds number, , m represents the exponential constant, represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear; The convection heat transfer coefficient of the tooth top includes: in, represents the lubricating oil Prandtl number, , represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear.

[0011] Preferably, the step S24 includes: calculating the friction heat flow of the gear meshing surface includes calculating the total friction heat flow at the contact position and the average friction heat flow obtained per rotation of the meshing teeth of the first gear and the second gear; wherein the total friction heat flow at the contact position includes: in, represents the average contact pressure at the contact position, Indicates the relative velocity of the contact position; represents the tooth surface friction coefficient, The coefficient that represents the rate at which frictional energy is converted into heat, Indicates the heat generated per unit time at the gear contact point; The average friction heat flow obtained by the meshing teeth of the first gear and the second gear per rotation includes: Among them, 2 a represents the Hertzian contact width, Indicates the speed of the driving wheel meshing point, Indicates the speed of the driven gear meshing point, T Indicates the operating cycle of the gear, Represents the frictional heat flow distribution coefficient of the meshing gear pair.

[0012] The present invention also provides an evaluation system for gear contact fatigue life considering multiple stress couplings, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the system implements the steps of a gear contact fatigue life evaluation method considering multiple stress couplings as described in any one of the above items.

[0013] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of a gear contact fatigue life assessment method considering multiple stress coupling as described in any one of the above items.

[0014] (3) Beneficial effects This application proposes a gear contact fatigue life assessment method that considers multi-stress coupling. The thermal stress generated by gear meshing is introduced into the gear contact analysis. Based on the Dang Van multi-axial fatigue criterion, the residual stress correction term is introduced to calculate the tooth surface contact fatigue life. The deep fusion assessment of multiple stresses including tooth surface contact stress, thermal stress and residual stress is realized, providing guidance for evaluating and improving the service life of gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic flow chart of a gear contact fatigue life assessment method considering multiple stress couplings provided in this embodiment; Figure 2 A schematic diagram of a gear mesh model for a gear contact fatigue life assessment method considering multiple stress coupling provided in this embodiment; Figure 3 A schematic diagram of the gear temperature field distribution of a gear contact fatigue life assessment method considering multiple stress coupling provided in this embodiment; Figure 4 Schematic diagram of a gear contact analysis model for a gear contact fatigue life assessment method considering multiple stress coupling provided in this embodiment Figure 5 A schematic diagram of gear stress distribution for a gear contact fatigue life assessment method considering multiple stress couplings provided in this embodiment; Figure 6 A schematic diagram of the arrangement of gear nodes for a gear contact fatigue life assessment method considering multiple stress couplings provided in this embodiment; Figure 7 A schematic diagram of fatigue life results along the tooth width direction at different depths on the tooth surface of a gear contact fatigue life assessment method considering multiple stress coupling provided in this embodiment; Figure 8 Schematic diagram of the hardware structure of a gear contact fatigue life evaluation system considering multiple stress coupling provided in this embodiment DETAILED DESCRIPTION In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0016] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0017] In addition, in the present invention, the terms "first," "second," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0018] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can refer to fixed connection, detachable connection, or integration; "connection" can refer to mechanical connection or electrical connection; it can refer to direct connection or indirect connection through an intermediate medium; it can refer to internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] like Figure 1 As shown, this embodiment provides a gear contact fatigue life assessment method considering multi-stress coupling, which includes steps S1 to S5.

[0020] S1: Construct a three-dimensional gear geometric model based on the gear geometric parameters to be evaluated. Specifically, the geometric parameters include: number of teeth, module, working side normal pressure angle, non-working side normal pressure angle, helix angle, hand direction, and tooth width.

[0021] Optionally, modeling is performed using a modeling tool, which can be selected according to actual conditions. For example, a precise gear tooth profile (involute curve) can be generated using professional CAD software (such as SolidWorks, UG NX) or a parametric script (such as Python + OpenCASCADE).

[0022] S2, constructing a gear thermal analysis model based on the gear three-dimensional geometric model, including: S21. Import the three-dimensional gear geometric model into finite element software for structural meshing. Local mesh refinement is performed in the tooth contact area and the tooth root working area, and mesh coarsening is performed in the remaining areas. Optionally, the finite element software is ANSYS Workbench 2023 R2. This version features advanced mesh processing capabilities, supports user-defined material parameters, and can interface with most computer-aided design (CAD) software to enable data sharing and exchange.

[0023] Specifically, the structural meshing includes using an 8-node hexahedral linear reduced integration unit (C3D8R) to perform structural meshing on the gear geometric model, and meshing the tooth surface contact area and the tooth root working area, while performing network sparse processing on other areas, so as to achieve a balance between the calculation accuracy and efficiency of the finite element model.

[0024] S22, based on the actual situation of the gear, define the gear-related material properties, specify the thermophysical parameters, and establish a steady-state heat transfer analysis step; the gear-related material properties include: elastic modulus, Poisson's ratio, density, specific heat capacity, and heat transfer coefficient.

[0025] S23, classifying convective heat transfer scenarios according to the operating environment of the gear, and calculating the convective heat transfer coefficients of the tooth surface, end face, and tooth top, respectively. During the calculation process, relevant material properties of the lubricating oil are introduced as important parameters for calculating the convective heat transfer coefficients. The relevant material properties of the lubricating oil include: kinematic viscosity, density, specific heat capacity, and thermal conductivity.

[0026] S24, calculate the friction heat flow of the gear meshing surface; S25, loading the calculation results of step S23 and step S24 into the gear three-dimensional geometric model to construct the gear thermal analysis model.

[0027] S3, based on the gear thermal analysis model, constructing a gear contact analysis model to calculate the gear tooth surface contact stress, including: S31, define the contact type and boundary conditions; according to the meshing relationship of the gear pair, determine that the contact surface of the first gear is the active surface, and the contact surface of the second gear is the passive surface, wherein the first gear is the driving wheel and the second gear is the driven wheel. The driving wheel is the power input wheel, which obtains energy from an external power source (such as a motor) and starts to rotate; the driven wheel is the power output wheel, which rotates under the drive of the driving wheel and transmits power to subsequent mechanical components.

[0028] Then, a surface-to-surface contact pair is established; and appropriate boundary conditions are set to simulate the actual working conditions; by establishing a surface-to-surface contact pair, the contact state between the gear tooth surfaces can be accurately simulated, which is highly consistent with the contact behavior of the gear tooth surfaces in actual conditions, making the analysis results more realistic and reliable.

[0029] In other embodiments, the first gear is a small gear, and the second gear is a large gear.

[0030] S32, apply load: apply load to the structural field model based on the actual working conditions, wherein the calculation results of the gear thermal analysis model are defined as temperature loads applied to the structural field model; by applying the thermal analysis results as temperature loads to the structural field model, the stress state of the gear under the actual working conditions can be more realistically simulated, making the analysis results closer to the actual situation.

[0031] S33, based on the step S31 and the step S32, construct a gear contact analysis model; calculate and obtain the gear tooth surface contact stress distribution for evaluating the fatigue life of subsequent gears.

[0032] S4, based on the Dang Van multiaxial fatigue criterion, introduces the residual stress correction term to construct a gear contact fatigue life assessment model: in, represents the maximum shear stress amplitude, represents the hydrostatic stress, represents the material parameters, represents the residual stress, represents the fatigue strength coefficient under pure torsion loading, represents the fatigue strength index under pure torsion loading, Represents contact fatigue life.

[0033] S5, calculating the gear contact fatigue life based on the gear-related actual working condition data and the gear contact fatigue life assessment model.

[0034] As a preferred embodiment of the present invention, the step S1 further includes, S11, simplifying the model: constructing a three-dimensional geometric model of the gear of the meshing portion based on the symmetry of the gear. By utilizing this symmetry, only constructing a three-dimensional geometric model of the gear of the meshing portion can greatly reduce the size of the model, thereby improving the computational efficiency. In other embodiments, based on the symmetry of the gear, only constructing a three-dimensional geometric model of the gear including one-quarter of the meshing portion. Optionally, the gear is a spur gear or a helical gear.

[0035] As a preferred embodiment of the present invention, the boundary condition setting in step S31 includes the following steps: S311, establishing a rigid reference point coupling constraint model: randomly selecting a point on the rotation axis of the first gear and the second gear to establish a rigid reference point, and constructing a coupling constraint model between the inner hole surface of the gear hub and the corresponding reference point; S312, setting the analysis steps and boundary conditions for contact analysis: Based on the finite element analysis software, create the initial contact setting analysis step, the torque application analysis step, and the speed application meshing transmission analysis step in a sequential order to simulate the contact and transmission process of the gears in stages; The initial contact setting analysis step includes: fixing all degrees of freedom of the first gear, applying a small rotational displacement to the axis degree of freedom of the second gear, causing the tooth surface of the first gear to contact the tooth surface of the second gear, and establishing an initial contact state; The torque application analysis step includes: releasing the rotational freedom of the second gear around its axis and applying torque to the second gear; The step of applying a rotational speed to realize meshing transmission analysis includes: applying a certain rotational speed on the axis of the first gear to realize meshing transmission of the gears; simulating the contact and transmission process of the gears in stages, which is more in line with the actual working process of the gears.

[0036] S313, defining the application object of the boundary condition: applying the torque to the reference point of the second gear, and applying the rotation angle corresponding to the rotation speed to the reference point of the first gear.

[0037] Specifically, the residual stress data in step S4 is obtained by testing the residual stress of the tooth surface, and the residual stress data of each measuring point of the gear specimen along the tooth thickness direction is obtained through experimental testing.

[0038] Optionally, in this embodiment, the fatigue strength coefficient under pure torsional loading in step S4 is The fatigue strength index under pure torsion loading The fatigue strength coefficient under pure torsional loading is obtained by performing a pure torsional fatigue test on a fatigue testing machine; applying a pure torsional load to a standard specimen of the gear material and recording the fatigue life of the specimen under different load levels; performing statistical analysis on the test data and fitting the fatigue life curve using a mathematical model. The fatigue strength index under pure torsion loading The value of .

[0039] Preferably, in step S23, the convective heat transfer between the gear and the lubricating oil and the air is divided into three cases, namely, the convective heat transfer of the tooth surface, the convective heat transfer of the end surface and the convective heat transfer of the tooth top, and the convective heat transfer coefficients of different surfaces are calculated, wherein: Convection heat transfer coefficient of the tooth surface include: in, represents the angular velocity, represents the thermal conductivity, Indicates the density of the lubricating oil, represents the specific heat capacity of the lubricating oil, Indicates the kinematic viscosity of the lubricating oil, represents the thermal diffusivity, , Indicates the tooth height at the meshing point, represents the radius of the meshing point, represents the normalized total cooling capacity; The flow state of lubricating oil on the gear end face can be divided into three types: laminar flow, transition laminar flow, and turbulent flow, which correspond to different Reynolds number value ranges. The convective heat transfer coefficient of the end face includes the convective heat transfer coefficient of the end face in the three flow states of laminar flow, transition laminar flow, and turbulent flow; wherein, The laminar flow state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the lubricating oil Prandtl number, , represents the Reynolds number, , m represents the exponential constant, represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear; The transition laminar state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the thermal conductivity of the lubricating oil, represents the characteristic speed of the gear, represents the characteristic length of the gear; The turbulent state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the lubricating oil Prandtl number, , represents the Reynolds number, , m represents the exponential constant, represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear; The convection heat transfer coefficient of the tooth top includes: in, represents the lubricating oil Prandtl number, , represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear.

[0040] Furthermore, in this embodiment, the step S24 includes: calculating the friction heat flow of the gear meshing surface includes calculating the total friction heat flow at the contact position and the average friction heat flow obtained per rotation of the meshing teeth of the first gear and the second gear; wherein the total friction heat flow at the contact position includes: in, represents the average contact pressure at the contact position, Indicates the relative velocity of the contact position; represents the tooth surface friction coefficient, The coefficient that represents the rate at which frictional energy is converted into heat, It indicates the heat generated per unit time at the gear contact point and is an important indicator for measuring gear friction heat generation.

[0041] The average friction heat flow obtained by the meshing teeth of the first gear and the second gear per rotation includes: Among them, 2 a represents the Hertzian contact width, Indicates the speed of the first gear meshing point; Indicates the speed of the second gear meshing point, T Indicates the operating cycle of the gear, Represents the frictional heat flow distribution coefficient of the meshing gear pair.

[0042] The following describes a gear contact fatigue life assessment method considering multiple stress couplings in this embodiment through a specific operation process: Step 1: Input the gear geometric parameters (see Table 1) and establish the gear 3D geometric model.

[0043] Table 1 Gear geometric parameters Step 2, such as Figure 2 As shown in the figure, the geometric model was imported into the finite element analysis software, and the gear geometry model was structurally meshed using an 8-node hexahedral linear reduced integration element (C3D8R). To balance the calculation accuracy and efficiency of the finite element model, the mesh was refined in the tooth surface contact area and the tooth root working area, while the mesh was sparsely processed in other areas.

[0044] Based on the actual situation of the gear (see Table 2), the gear-related material properties are defined, the thermophysical parameters are specified, and a steady-state heat transfer analysis step is established; Table 2 Gear material properties like Figure 3 As shown in the figure, the convective heat transfer scenarios are divided according to the operating environment on the gear, wherein the lubricating oil material parameters (see Table 3) calculate the convective heat transfer coefficient of each tooth surface and the friction heat flow of the meshing surface and define them into the finite element model, construct the gear thermal analysis model, and complete the gear thermal analysis model simulation.

[0045] Table 3 Lubricant material properties Step three: According to the meshing relationship of the gear pair, the contact surface of the driving gear is determined as the active surface, and the contact surface of the driven gear is determined as the passive surface. A rigid reference point coupling constraint model is adopted, that is, a rigid reference point is established at any point on the rotation axis of the large and small wheels respectively, and a coupling constraint model is established between the inner hole surface of the gear hub and the reference point, so that the boundary conditions applied on the reference point are equivalent to the coupling area.

[0046] During contact analysis, the speed and torque are set in different analysis steps: 1) All degrees of freedom of the small wheel are fixed, and a small rotational displacement is applied to the large gear axis to make the small wheel tooth surface contact with the large gear tooth surface; 2) The large gear rotational freedom around its axis is released and torque is applied; 3) A certain speed is applied to the small wheel axis to achieve meshing transmission of the gear pair.

[0047] like Figure 4 and Figure 5 As shown in the figure, the torque and angle are applied to the reference points of the large wheel and the small wheel respectively. Set the loading torque to The results of gear thermal analysis are applied as temperature loads to the structural field, a gear contact analysis model is constructed, and the tooth surface contact stress is obtained.

[0048] Step 4: Based on the modified Dang Van multiaxial fatigue criterion, combined with the tooth surface residual stress data (see Table 4), and the gear material torsional SN curve, the fatigue strength coefficient and fatigue strength index are calculated. =3060MPa, =-0.1237.

[0049] Table 4 Residual stress distribution on tooth surface Then the gear contact fatigue life is calculated using the gear contact fatigue life assessment model: in, represents the maximum shear stress amplitude, represents the hydrostatic stress, represents the material parameters, represents the residual stress, represents the fatigue strength coefficient under pure torsion loading, represents the fatigue strength index under pure torsion loading, Indicates contact fatigue life; like Figure 6 and Figure 7 As shown in the figure, the contact fatigue life of the nodes on the gear pitch line at 0.25, 0.50 and 0.75 times the tooth width along the layer depth direction is calculated.

[0050] The present invention also provides an evaluation system for gear contact fatigue life considering multiple stress couplings, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of a gear contact fatigue life evaluation method considering multiple stress couplings as described above are implemented.

[0051] like Figure 8 The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of a gear contact fatigue life assessment method considering multiple stress coupling as described above.

[0052] Figure 8 FIG. 1 is a schematic diagram of the hardware structure for running a gear contact fatigue life assessment method considering multiple stress couplings provided by an embodiment of the present invention. Figure 8As shown, this embodiment / computer 6 includes: a processor 60, a memory 61, and a computer program 62 stored in the memory 61 and executable on the processor 60, such as a program for executing a method for assessing the contact fatigue life of gears considering multiple stress couplings. When the processor 60 executes the computer program 62, it implements the steps described in the aforementioned embodiments of the method for assessing the contact fatigue life of gears considering multiple stress couplings. Alternatively, when the processor 60 executes the computer program 62, it implements the functions of the modules / units described in the aforementioned device embodiments.

[0053] For example, the computer program 62 may be divided into one or more modules / units, which are stored in the memory 61 and executed by the processor 60 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program 62 in the computer 6.

[0054] The computer 6 can be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The computer 6 device can include, but is not limited to, a processor 60 and a memory 61. It can be understood by those skilled in the art that Figure 8 This is only an example of computer 6 and does not constitute a limitation on computer 6. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the computer 6 may also include input and output devices, network access devices, buses, etc.

[0055] The processor 60 may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0056] The memory 61 can be an internal storage unit of the computer 6, such as the computer's hard drive or memory. Alternatively, the memory 61 can be an external storage device of the computer 6, such as a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory card, etc., equipped on the terminal device. Furthermore, the memory 61 can include both the internal storage unit of the computer 6 and an external storage device. The memory 61 is used to store the computer program and other programs and data required by the terminal device. The memory 61 can also be used to temporarily store data that has been output or is about to be output.

[0057] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0058] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0059] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0060] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0061] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0062] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0063] If the integrated module / unit is implemented as a software functional unit and sold or used as a standalone product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention can implement all or part of the process steps in the above-mentioned method embodiments by using a computer program to instruct the relevant hardware. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal, and software distribution medium. It should be noted that the content of the computer-readable medium can be appropriately increased or decreased based on the requirements of legislation and patent practice in a jurisdiction. For example, in some jurisdictions, based on legislation and patent practice, computer-readable media does not include electric carrier signals and telecommunication signals.

[0064] The above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. In addition to the above embodiments, the present invention may also have other implementations. Any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection claimed by the present invention.

Claims

1. A gear contact fatigue life assessment method considering multiple stress couplings, characterized in that: Including steps: S1, constructing a three-dimensional geometric model of the gear according to the geometric parameters of the gear to be evaluated; S2, constructing a gear thermal analysis model based on the gear three-dimensional geometric model, including: S21, importing the gear three-dimensional geometric model into finite element software, performing structural mesh division, performing local mesh encryption in the tooth surface contact area and the tooth root working area, and performing mesh coarsening processing in the remaining areas; S22, based on the actual situation of the gear, defining the gear-related material properties, specifying the thermophysical parameters, and establishing a steady-state heat transfer analysis step; S23, dividing the convective heat transfer scenarios according to the operating environment of the gear, and calculating the convective heat transfer coefficient of the tooth surface, the convective heat transfer coefficient of the end face, and the convective heat transfer coefficient of the tooth top respectively; S24, calculate the friction heat flow of the gear meshing surface; S25, loading the calculation results of step S23 and step S24 into the gear three-dimensional geometric model to construct the gear thermal analysis model; S3, based on the gear thermal analysis model, constructing a gear contact analysis model to calculate the gear tooth surface contact stress, including: S31, defining the contact type and boundary conditions; based on the meshing relationship of the gear pair, determining the contact surface of the first gear as the active surface and the contact surface of the second gear as the passive surface, thereby establishing a surface-to-surface contact pair; and setting appropriate boundary conditions to simulate actual working conditions; S32, applying a load: applying a load to the structural field model based on the actual working condition, wherein the calculation result of the gear thermal analysis model is defined as a temperature load applied to the structural field model; S33, based on the step S31 and the step S32, constructing a gear contact analysis model; calculating the gear tooth surface contact stress distribution for evaluating the fatigue life of subsequent gears; S4, based on the Dang Van multiaxial fatigue criterion, introduces the residual stress correction term to construct a gear contact fatigue life assessment model: in, represents the maximum shear stress amplitude, represents the hydrostatic stress, represents the material parameters, represents the residual stress, represents the fatigue strength coefficient under pure torsion loading, represents the fatigue strength index under pure torsion loading, Indicates contact fatigue life; S5, calculating the gear contact fatigue life based on the actual working condition data of the gear and according to the gear contact fatigue life assessment model.

2. The gear contact fatigue life assessment method considering multiple stress coupling according to claim 1, characterized in that: The step S1 further includes: S11: simplifying the model, and constructing a three-dimensional geometric model of the gear of the meshing part based on the symmetry of the gear.

3. The gear contact fatigue life assessment method considering multiple stress coupling according to claim 1, characterized in that: The gear is a spur gear or a helical gear.

4. The gear contact fatigue life assessment method considering multiple stress coupling according to claim 1, characterized in that: The boundary condition setting in step S31 includes the following steps: S311, establishing a rigid reference point coupling constraint model: randomly selecting a point on the rotation axis of the first gear and the second gear to establish a rigid reference point, and constructing a coupling constraint model between the inner hole surface of the gear hub and the corresponding reference point; S312, setting the analysis steps and boundary conditions for contact analysis: Based on the finite element analysis software, create the initial contact setting analysis step, the torque application analysis step, and the speed application meshing transmission analysis step in a sequential order to simulate the contact and transmission process of the gears in stages; The initial contact setting analysis step includes: fixing all degrees of freedom of the first gear, applying a small rotational displacement to the axis degree of freedom of the second gear, causing the tooth surface of the first gear to contact the tooth surface of the second gear, and establishing an initial contact state; The torque application analysis step includes: releasing the rotational freedom of the second gear around its axis and applying torque to the second gear; The step of applying a rotational speed to realize meshing transmission analysis includes: applying a certain rotational speed on the axis of the first gear to realize meshing transmission of the gears; S313, defining the application object of the boundary condition: applying the torque to the reference point of the second gear, and applying the rotation angle corresponding to the rotation speed to the reference point of the first gear.

5. The gear contact fatigue life assessment method considering multiple stress coupling according to claim 1, characterized in that: The residual stress data in step S4 is obtained by testing the residual stress on the tooth surface.

6. The gear contact fatigue life assessment method considering multiple stress coupling according to claim 5, characterized in that: The fatigue strength coefficient under pure torsion loading in step S4 The fatigue strength index under pure torsion loading The fatigue strength coefficient under pure torsional loading is obtained by performing a pure torsional fatigue test on a fatigue testing machine; applying a pure torsional load to a standard specimen of the gear material and recording the fatigue life of the specimen under different load levels; performing statistical analysis on the test data and fitting the fatigue life curve using a mathematical model. The fatigue strength index under pure torsion loading The value of .

7. The gear contact fatigue life assessment method considering multiple stress coupling according to claim 1, characterized in that: In step S23, The convection heat transfer coefficient of the tooth surface include: in, represents the angular velocity, represents the thermal conductivity, Indicates the density of the lubricating oil, represents the specific heat capacity of the lubricating oil, Indicates the kinematic viscosity of the lubricating oil, represents the thermal diffusivity, , Indicates the tooth height at the meshing point, represents the radius of the meshing point, represents the normalized total cooling capacity; The convective heat transfer coefficient of the end surface includes the convective heat transfer coefficient of the end surface in three flow states: laminar flow state, transition laminar flow state, and turbulent flow state; wherein, The laminar flow state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the lubricating oil Prandtl number, , represents the Reynolds number, , m represents the exponential constant, represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear; The transition laminar state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the thermal conductivity of the lubricating oil, represents the characteristic speed of the gear, represents the characteristic length of the gear; The turbulent state: When the Reynolds number When , the end face flow heat transfer coefficient is: in, represents the lubricating oil Prandtl number, , represents the Reynolds number, , m represents the exponential constant, represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear; The convection heat transfer coefficient of the tooth top includes: in, represents the lubricating oil Prandtl number, , represents the thermal conductivity of the lubricating oil, Indicates the characteristic speed of the gear.

8. The gear contact fatigue life assessment method considering multiple stress coupling according to claim 7, characterized in that: The step S24 includes: calculating the friction heat flow of the gear meshing surface includes calculating the total friction heat flow at the contact position and the average friction heat flow obtained per rotation of the meshing teeth of the first gear and the second gear; wherein the total friction heat flow at the contact position includes: in, represents the average contact pressure at the contact position, represents the relative velocity of the contact position, represents the tooth surface friction coefficient, The coefficient that represents the rate at which frictional energy is converted into heat, Indicates the heat generated per unit time at the gear contact point; The average friction heat flow obtained by the meshing teeth of the first gear and the second gear per rotation includes: Among them, 2 a represents the Hertzian contact width, Indicates the speed of the driving wheel meshing point, Indicates the speed of the driven gear meshing point, T Indicates the operating cycle of the gear, Represents the frictional heat flow distribution coefficient of the meshing gear pair.

9. A gear contact fatigue life evaluation system considering multiple stress couplings, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the gear contact fatigue life assessment method considering multiple stress couplings are implemented as described in any one of claims 1 to 8.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of a gear contact fatigue life assessment method considering multiple stress couplings are implemented as claimed in any one of claims 1 to 8.

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