A method for evaluating gear contact fatigue life considering multi-stress coupling

Abstract

The application discloses a kind of gear contact fatigue life evaluation method considering multi-stress coupling, it is related to gear life evaluation technical field, including: reading gear geometry data, residual stress depth data, material fatigue data, residual stress relaxation calibration data and local contact stiffness calibration data, obtain gear contact fatigue evaluation basic data;Determine current load calculation section, distribute total normal load, bind to generate multi-stress synchronous component record;Extract gear surface normal contact stress history, generate effective fatigue cycle record, screen synchronous participation stress, generate residual stress update record;Compare accumulated fatigue damage record with fatigue termination cumulative damage value, update the initial local contact stiffness of next load calculation section in un-termination state, backflow next load calculation section input record or output gear contact fatigue life evaluation result;The consistency of traceability and service evolution characterization of gear contact fatigue life evaluation result is improved.

Description

Technical Field

[0001] This invention relates to the field of gear life assessment technology, and in particular to a method for assessing gear contact fatigue life considering multi-stress coupling. Background Technology

[0002] Gear drives are widely used in vehicles, construction machinery, wind power equipment, and industrial reduction systems. The fatigue life assessment of tooth surface contact is usually based on gear geometric parameters, material fatigue performance, operating load, lubrication status, and temperature conditions. The tooth surface contact trajectory and evaluation position are determined, the contact stress history is calculated, and the risk of fatigue failure such as pitting and spalling is estimated by combining the number of cycles and the damage accumulation criterion. This provides a calculation basis for gear design verification, service life prediction, and maintenance cycle determination.

[0003] Under complex service conditions, load fluctuations, frictional slippage, tooth surface temperature rise, and residual stress will act on the tooth surface simultaneously. Conventional evaluation methods can calculate tooth surface contact stress and fatigue damage, but there is still room for refinement in the correspondence between different stress components and the same tooth surface position and the same meshing moment. At the same time, after fatigue damage accumulates, residual stress relaxation and changes in local contact stiffness will affect subsequent load distribution. Conventional evaluation processes still have room for further improvement in the continuous updating expression of subsequent load distribution changes. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a gear contact fatigue life assessment method that considers multi-stress coupling to solve the problems of insufficient precision in the synchronous coupling of multi-stress components and insufficient feedback updates of residual stress and local contact stiffness in fatigue damage evolution in the existing technology.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a method for assessing gear contact fatigue life considering multi-stress coupling, comprising: reading gear geometric data, residual stress depth data, material fatigue data, residual stress relaxation calibration data, and local contact stiffness calibration data; generating tooth surface contact trajectory records and layer depth evaluation records; binding them to form tooth surface evaluation points; registering initial state data; and obtaining basic data for gear contact fatigue assessment; based on the basic data for gear contact fatigue assessment, determining the current load calculation segment, organizing the meshing time sequence, allocating the total normal load, calculating five types of multi-stress components, and binding them to generate records of multi-stress synchronous components; and based on the records of multi-stress synchronous components... The system records and extracts the normal contact stress history of the tooth surface, generates an effective fatigue cycle record, filters synchronously involved stresses, forms an effective fatigue cycle damage record, calculates the cumulative amount of residual stress relaxation, updates the initial residual stress of the next load calculation segment, and generates a residual stress update record. It reads the effective fatigue cycle damage record and the residual stress update record, generates a cumulative fatigue damage record, compares the cumulative fatigue damage record with the cumulative damage value at fatigue termination, updates the initial local contact stiffness of the next load calculation segment in the non-termination state, generates the input record for the next load calculation segment, and either recycles the input record of the next load calculation segment or outputs the gear contact fatigue life assessment result.

[0008] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the step of generating tooth surface contact trajectory records and layer depth evaluation records, and binding them to form tooth surface evaluation points, includes: reading gear geometric data, determining the sequence of engagement, node, and disengagement positions, organizing the three-dimensional coordinates of the tooth surface along the meshing direction to form a gear geometric record, combining the meshing motion relationship record, extracting the three-dimensional coordinates of the tooth surface involved in the contact, and generating a tooth surface contact trajectory record; establishing a layer depth evaluation record based on residual stress depth data, material fatigue data, and residual stress relaxation calibration data, and binding the tooth surface contact trajectory record with the layer depth evaluation record to generate tooth surface evaluation points.

[0009] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the step of registering initial state data and obtaining basic data for gear contact fatigue assessment includes: registering initial state data based on tooth surface evaluation points, organizing service process records, generating load calculation segments, associating tooth surface evaluation points, load calculation segments, and initial state data to generate basic data for gear contact fatigue assessment.

[0010] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the steps of determining the current load calculation segment, organizing the meshing time sequence, and allocating the total normal load based on the gear contact fatigue assessment basic data include: registering the current load calculation segment according to the load calculation segment number and service time sequence; generating a meshing time sequence by combining the start meshing cycle, end meshing cycle, sampling time, and tooth surface contact trajectory points; matching the correspondence between tooth surface evaluation points and tooth surface contact trajectory points according to the tooth surface contact trajectory points in the meshing time sequence to determine the evaluation points and generate a record of the evaluation points; converting the total normal load according to the torque data, gear geometry record, center distance, and meshing motion relationship record in the current load calculation segment; and allocating the total normal load at the same meshing time by combining the current local contact stiffness in the evaluation point record to generate the allocated normal load.

[0011] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the calculation of five types of multi-stress components and the binding of multi-stress synchronous component records includes: calculating the tooth surface normal contact stress based on the allocated normal load; combining the friction coefficient, rolling ratio, sliding direction, load fluctuation data composed of start-stop load, impact load, and reverse load in the current load calculation segment, and temperature data, calculating the tooth surface friction shear stress, load fluctuation additional stress, and tooth surface thermal stress; and synchronously registering the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress as five types of multi-stress components according to the same tooth surface evaluation point, the same load calculation segment, and the same meshing time to generate a multi-stress synchronous component record for the current load calculation segment.

[0012] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the step of extracting the tooth surface normal contact stress history and generating an effective fatigue cycle record based on the multi-stress synchronous component record includes: collecting five types of multi-stress components within the same tooth surface evaluation point and the same load calculation segment from the multi-stress synchronous component record; combining the correspondence between the tooth surface evaluation point and the layer depth evaluation record to form the stress history record of the current load calculation segment; extracting the tooth surface normal contact stress history according to the order of meshing time based on the stress history record; dividing the contact cycle by the meshing time and the meshing exit time to generate an effective fatigue cycle record.

[0013] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the calculation of the cumulative residual stress relaxation, updating the initial residual stress of the next load calculation segment, and generating a residual stress update record includes: based on the effective fatigue cycle record, comparing the action time intervals of tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and the current residual stress, screening synchronously participating stresses, and generating synchronously participating stress records and segmented effective fatigue cycle records; establishing a local coordinate system for the tooth surface using the synchronously participating stress records and segmented effective fatigue cycle records, and integrating the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, and... The tooth surface thermal stress and current residual stress are mapped to a three-dimensional stress tensor to form a multiaxial stress state. The maximum shear stress amplitude, the average hydrostatic stress, and the number of cycles that can be withstood are obtained. Based on the effective fatigue cycle record or the cycle start meshing cycle number and cycle end meshing cycle number corresponding to the effective fatigue cycle record or the segmented effective fatigue cycle record, as well as the number of load spectrum repetitions in the load calculation segment record, the actual number of cycles is generated, and the effective fatigue cycle damage record is obtained. Based on the effective fatigue cycle damage record, combined with temperature data and the actual number of cycles, the cumulative amount of residual stress relaxation is calculated, the residual stress relaxation calibration data is matched, the initial residual stress of the next load calculation segment is updated, and the residual stress update record is generated.

[0014] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the step of generating cumulative fatigue damage records and comparing the cumulative fatigue damage records with the cumulative damage value at fatigue termination includes: collecting effective fatigue cycle damage records, accumulating fatigue damage increments according to the tooth surface evaluation points and load calculation segment numbers, and generating cumulative fatigue damage records; comparing the cumulative fatigue damage records with the cumulative damage value at fatigue termination, generating a life termination candidate record when the cumulative damage value at fatigue termination is reached, and registering an unterminated state when the cumulative damage value at fatigue termination is not reached.

[0015] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the step of updating the initial local contact stiffness of the next load calculation segment and generating the input record of the next load calculation segment in the unterminated state includes: based on the cumulative fatigue damage record corresponding to the unterminated state, aggregating the cumulative fatigue damage corresponding to the tooth surface evaluation point according to the tooth surface contact trajectory point, generating the equivalent cumulative fatigue damage of the tooth surface contact trajectory point, reading and matching the local contact stiffness calibration data corresponding to the tooth surface contact trajectory point, updating the initial local contact stiffness of the next load calculation segment according to the equivalent cumulative fatigue damage of the tooth surface contact trajectory point, and combining the residual stress update record to bind the initial local contact stiffness of the next load calculation segment corresponding to the tooth surface contact trajectory point and the initial residual stress of the next load calculation segment corresponding to the tooth surface evaluation point, thereby generating the input record of the next load calculation segment.

[0016] As a preferred embodiment of the gear contact fatigue life assessment method considering multi-stress coupling described in this invention, the reflow of the input record or output of the gear contact fatigue life assessment result for the next load calculation segment includes: when no life termination candidate record is generated and a next load calculation segment exists, the input record for the next load calculation segment is reflowed; when no life termination candidate record is generated and a next load calculation segment does not exist, an assessment result without termination is generated; when a life termination candidate record is generated, the fatigue danger location is determined, and a life traceability record and a gear contact fatigue life assessment result are generated.

[0017] The beneficial effects of this invention are as follows: By generating multi-stress synchronous component records, the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress are unified at the tooth surface evaluation point, load calculation segment, and meshing moment; by extracting the tooth surface normal contact stress history to generate effective fatigue cycle records, synchronously participating stresses are screened to form effective fatigue cycle damage records and calculate the cumulative amount of residual stress relaxation, realizing the correspondence between effective fatigue cycle damage and current residual stress update; by updating the initial local contact stiffness of the next load calculation segment through the cumulative fatigue damage record and generating the input record of the next load calculation segment, the traceability of gear contact fatigue life assessment results and the consistency of service evolution characterization are improved. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart for a gear contact fatigue life assessment method that considers multiple stress coupling.

[0020] Figure 2 A flowchart for generating multi-stress synchronous component records.

[0021] Figure 3 A flowchart for generating residual stress update records.

[0022] Figure 4 This is a flowchart for inputting records for the next load calculation segment.

[0023] Figure 5 This is a diagram showing the evolution of multiple stress synchronous components.

[0024] Figure 6 This is an updated diagram of the current residual stress. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] Reference Figures 1-6 This is one embodiment of the present invention, which provides a method for evaluating gear contact fatigue life considering multiple stress couplings, including the following steps:

[0029] S1. Read gear geometry data, residual stress depth data, material fatigue data, residual stress relaxation calibration data, and local contact stiffness calibration data; generate tooth surface contact trajectory records and layer depth evaluation records; bind them to form tooth surface evaluation points; register initial state data; and obtain basic data for gear contact fatigue assessment.

[0030] Read the gear geometry data, determine the sequence of engagement, node, and disengagement positions, organize the three-dimensional coordinates of the tooth surface along the meshing direction to form a gear geometry record, combine with the meshing motion relationship record, extract the three-dimensional coordinates of the tooth surfaces involved in the contact, and generate a tooth surface contact trajectory record.

[0031] Furthermore, the gear geometry data of the gear pair to be evaluated is read to generate a gear geometry record.

[0032] The gear geometry data includes the number of teeth, module, pressure angle, helix angle, tooth width, three-dimensional coordinates of the tooth surface, tooth surface normal vector, tooth surface tangent vector, tooth surface curvature, driving gear number, driven gear number, center distance, and recording of meshing motion relationships.

[0033] Furthermore, the three-dimensional coordinates of the tooth surface are read, and the order of engagement, disengagement, and engagement positions in the three-dimensional coordinates of the tooth surface is determined according to the meshing motion relationship record. The three-dimensional coordinates of the tooth surface are sorted according to the meshing direction, and the tooth height position, tooth width position, tooth surface normal vector, tooth surface tangent vector, and tooth surface curvature corresponding to each three-dimensional coordinate of the tooth surface are recorded to form a gear geometry record.

[0034] Furthermore, based on the gear geometry record and meshing motion relationship record, the tooth surface contact trajectory is generated.

[0035] Specifically, the three-dimensional coordinates of the tooth surfaces involved in the contact are extracted sequentially along the engagement position, node position, and disengagement position, and the order of the three-dimensional coordinates of the tooth surfaces during continuous meshing is registered as the tooth surface contact trajectory.

[0036] It should be noted that for each tooth surface contact trajectory point, the three-dimensional coordinates of the tooth surface, tooth height position, tooth width position, tooth surface normal vector, tooth surface tangent vector, tooth surface curvature, contact sequence number, and the corresponding meshing position of the tooth surface contact trajectory point are registered to obtain the tooth surface contact trajectory record. Among them, the contact sequence number is registered continuously in the order from the engagement position to the disengagement position, and the corresponding meshing position of the tooth surface contact trajectory point is determined according to the contact sequence number, engagement position, node position, and disengagement position. The corresponding meshing position of the tooth surface contact trajectory point is bound to the same tooth surface contact trajectory point for registration.

[0037] Based on residual stress depth data, material fatigue data, and residual stress relaxation calibration data, a layer depth evaluation record is established. The tooth surface contact trajectory record is then bound to the layer depth evaluation record to generate tooth surface evaluation points.

[0038] Based on the tooth surface evaluation points, initial state data is registered, service process records are organized, load calculation segments are generated, and tooth surface evaluation points, load calculation segments, and initial state data are associated to generate basic data for gear contact fatigue assessment.

[0039] Furthermore, residual stress depth data, material fatigue data, and residual stress relaxation calibration data are read to generate layer depth evaluation records.

[0040] It should be noted that the residual stress depth data includes the detected layer depth location, corresponding residual compressive or tensile stress, material grade, heat treatment marking, and surface treatment marking; the material fatigue data includes the material grade, layer depth location, material shear fatigue data, tensile and compressive fatigue data, multiaxial fatigue data, and cumulative damage value at fatigue termination; the residual stress relaxation calibration data includes the material grade, heat treatment marking, surface treatment marking, layer depth location, cumulative residual stress relaxation amount, and corresponding residual stress.

[0041] It should be noted that in this embodiment, the layer depth evaluation record is established according to the existing layer depth positions in the residual stress depth data, and no new undetected layer depth positions are added; when the tooth surface evaluation point needs to read the residual stress between adjacent detected layer depths, interpolation is only performed between adjacent detected layer depths; when the target layer depth exceeds the coverage range of the residual stress depth data, no tooth surface evaluation point exceeding the coverage range is generated; the layer depth evaluation record includes the layer depth position, corresponding residual stress, material grade, heat treatment identifier, surface treatment identifier, material fatigue data index, residual stress relaxation calibration data index, and the source of fatigue termination cumulative damage value.

[0042] Furthermore, the tooth surface contact trajectory record is bound to the layer depth evaluation record to generate tooth surface evaluation points.

[0043] Specifically, during the binding process, the tooth surface contact trajectory points in the tooth surface contact trajectory record are read one by one, and the layer depth positions in the layer depth evaluation record are read one by one. The same tooth surface contact trajectory point is combined with each layer depth position to form a tooth surface evaluation point.

[0044] It should be noted that each tooth surface evaluation point records the three-dimensional coordinates of the tooth surface, tooth height position, tooth width position, layer depth position, tooth surface normal vector, tooth surface tangent vector, tooth surface curvature, initial residual stress, and cumulative damage value at fatigue termination. Among them, the initial residual stress is obtained from the residual stress at the corresponding layer depth position in the layer depth evaluation record; the cumulative damage value at fatigue termination is obtained from the data corresponding to the material grade and layer depth position in the material fatigue data; when there are cumulative damage values ​​at fatigue termination for adjacent layer depth positions in the material fatigue data, interpolation is performed according to the measured data between adjacent layer depth positions; when the material fatigue data does not cover the layer depth position of the tooth surface evaluation point, no corresponding tooth surface evaluation point is generated.

[0045] Furthermore, the local contact stiffness calibration data is read and bound to the tooth surface evaluation point to generate initial state data.

[0046] It should be noted that the local contact stiffness calibration data includes tooth surface contact trajectory points, cumulative fatigue damage state, and corresponding local contact stiffness.

[0047] Specifically, for each tooth surface contact trajectory point, the local contact stiffness corresponding to the calibration state where the cumulative fatigue damage is zero in the local contact stiffness calibration data is read and registered as the current local contact stiffness of the tooth surface contact trajectory point; the current local contact stiffness of the tooth surface contact trajectory point is bound to the tooth surface evaluation point under the same tooth surface contact trajectory point; the initial residual stress corresponding to the tooth surface evaluation point is registered as the current residual stress; the cumulative fatigue damage is registered as zero, corresponding to the initial state before the start of the load calculation segment processing where no fatigue damage has been accumulated; the cumulative amount of residual stress relaxation is registered as zero, corresponding to the initial state before the start of the load calculation segment processing where no residual stress relaxation process has been generated.

[0048] The initial state data includes the current residual stress, the current local contact stiffness at the tooth surface contact trajectory point, the cumulative fatigue damage, and the cumulative amount of residual stress relaxation.

[0049] Furthermore, it reads operating load data, speed data, lubrication data, and temperature data to generate service process records.

[0050] The operating load data includes torque, start-stop load, impact load, reverse load, load sampling time, and load spectrum repetition number arranged in service sequence. The torque arranged in service sequence is used to calculate the total normal load at the current meshing moment. The start-stop load, impact load, and reverse load constitute the load fluctuation data. The load fluctuation data includes start-stop load, impact load, reverse load, occurrence time, and duration of action. The speed data includes the speed sampling time and corresponding speed. The lubrication data includes the friction coefficient, sliding ratio, and sliding direction. The temperature data includes the tooth surface temperature and meshing flash temperature.

[0051] The sampling times of load, rotational speed, lubrication data, and temperature are organized in chronological order. Samples from the same time are merged and recorded together. Samples from different sources are arranged in chronological order to form a service process time record. Each service process time record records the torque, rotational speed, friction coefficient, sliding ratio, sliding direction, tooth surface temperature, and meshing flash temperature at the corresponding time.

[0052] Furthermore, based on the service process records and tooth surface contact trajectory records, load calculation segments are generated.

[0053] Specifically, a load calculation segment is formed according to the meshing process covered between adjacent service process time records. The start and end times, speed data, and gear geometry records of adjacent service process time records are used to determine the start and end meshing cycles corresponding to the load calculation segment. The start and end meshing cycles, torque data, load fluctuation data, speed data, load direction, sliding direction, friction coefficient, rolling ratio, tooth surface temperature, meshing flash temperature, and corresponding tooth surface contact trajectory points corresponding to the load calculation segment are recorded in the load calculation segment record.

[0054] It should be noted that when the operational load data includes the number of load spectrum repetitions, the number of load spectrum repetitions is recorded in the load calculation section record; when the operational load data does not include the number of load spectrum repetitions, the number of load spectrum repetitions in the load calculation section record is recorded as the number of times the service is covered; the number of load spectrum repetitions is obtained from the operational load data.

[0055] By linking the tooth surface evaluation points, load calculation segments, and initial state data, basic data for gear contact fatigue assessment is generated.

[0056] It should be noted that the basic data for gear contact fatigue assessment includes tooth surface evaluation points, load calculation segments, current residual stress, current local contact stiffness, cumulative fatigue damage, cumulative residual stress relaxation, cumulative damage value at fatigue termination, the correspondence between tooth surface evaluation points and tooth surface contact trajectory points, the correspondence between tooth surface evaluation points and layer depth evaluation records, and the correspondence between load calculation segments and tooth surface contact trajectory points.

[0057] S2. Based on the basic data of gear contact fatigue assessment, determine the current load calculation segment, organize the meshing time sequence, allocate the total normal load, calculate five types of multi-stress components, and bind and generate multi-stress synchronous component records.

[0058] According to the load calculation segment number and the order of service time, the current load calculation segment is registered, and the meshing time sequence is generated by combining the start meshing cycle, the end meshing cycle, the sampling time and the tooth surface contact trajectory point.

[0059] Furthermore, the basic data for gear contact fatigue assessment is read to determine the current load calculation segment.

[0060] Specifically, according to the load calculation segment number and service time order in the load calculation segment record, the load calculation segment that is ranked first and has not yet completed the generation of multi-stress synchronous component records is registered as the current load calculation segment.

[0061] It should be noted that the current load calculation segment reads the following content: the start of meshing cycle, the end of meshing cycle, torque data, speed data, load direction, sliding direction, friction coefficient, rolling ratio, tooth surface temperature, meshing flash temperature, and the corresponding tooth surface contact trajectory points; the first load calculation segment reads the current residual stress and the current local contact stiffness; subsequent load calculation segments read the residual stress update record and the local contact stiffness update record formed after the end of the previous load calculation segment.

[0062] It should be noted that when the subsequent load calculation segment begins processing, the initial residual stress of the next load calculation segment generated by the previous load calculation segment is registered as the current residual stress of the subsequent load calculation segment, and the initial local contact stiffness of the next load calculation segment generated by the previous load calculation segment is registered as the current local contact stiffness of the subsequent load calculation segment.

[0063] Furthermore, based on the current load calculation segment, the meshing time sequence is organized. Specifically, the start and end meshing cycles of the current load calculation segment are read, and the meshing times are recorded in the order of engagement position, node position, and disengagement position, combined with the rotational speed data and tooth surface contact trajectory records. The load sampling time, rotational speed sampling time, lubrication data sampling time, and temperature sampling time are synchronously incorporated into the meshing time sequence. Identical sampling times are merged and recorded, and different sampling times are arranged in chronological order.

[0064] It should be noted that for each meshing moment in the meshing time sequence, the torque, speed, load direction, sliding direction, friction coefficient, rolling ratio, tooth surface temperature, meshing flash temperature, and corresponding tooth surface contact trajectory point are recorded. When the meshing moment is between two adjacent sampling moments, the torque, speed, friction coefficient, rolling ratio, tooth surface temperature, and meshing flash temperature are obtained by linear interpolation between the two adjacent sampling moments. The load direction and sliding direction are based on the state recorded at the previous sampling moment until updated at the next sampling moment.

[0065] Based on the tooth surface contact trajectory points in the meshing time sequence, the correspondence between the tooth surface evaluation points and the tooth surface contact trajectory points is matched to determine the evaluation points and generate a record of the evaluation points.

[0066] Based on the torque data, gear geometry records, center distance, and meshing motion relationship records in the current load calculation segment, the total normal load is converted. Combined with the current local contact stiffness in the records of the evaluation points, the total normal load at the same meshing moment is allocated to generate the allocated normal load.

[0067] Furthermore, based on the meshing time sequence, the evaluation points are determined.

[0068] Specifically, the tooth surface contact trajectory points corresponding to each meshing moment are read. Based on the correspondence between the tooth surface evaluation points and the tooth surface contact trajectory points, the tooth surface evaluation points bound to the current tooth surface contact trajectory points are selected, and the selected tooth surface evaluation points are registered as evaluation points.

[0069] It should be noted that the tooth surface evaluation points corresponding to different layer depths under the same tooth surface contact trajectory point inherit the torque, speed, load direction, sliding direction, friction coefficient, rolling ratio, tooth surface temperature and meshing flash temperature at the same meshing moment. At the same time, the layer depth position and the current residual stress are retained respectively, and they are all bound to the current local contact stiffness of the corresponding tooth surface contact trajectory point to generate the evaluation point record.

[0070] Based on the correspondence between the tooth surface evaluation points and the layer depth evaluation records, the material grade, heat treatment identifier, surface treatment identifier, and material fatigue data index corresponding to the evaluation points are read; according to the material fatigue data index, the material elastic modulus, material Poisson's ratio, and material thermal expansion coefficient are read from the material fatigue data, and the material elastic modulus, material Poisson's ratio, and material thermal expansion coefficient are registered in the evaluation point record.

[0071] Furthermore, based on the records of the evaluation points and the current local contact stiffness, the total normal load is allocated.

[0072] Specifically, based on the torque data at the current meshing moment, gear geometry records, center distance, and meshing motion relationship records, the tangential load on the tooth surface is calculated using the torque data and the pitch circle radius of the driving gear, and the total normal load is calculated based on the pressure angle and helix angle.

[0073] It should be noted that the total normal load is obtained by converting the torque data and gear geometry record at the current meshing moment. The change in total normal load caused by the torque arranged in the service sequence has been registered through the tooth surface normal contact stress at the current meshing moment. The additional changes caused by start-stop load, impact load and reverse load are not included in the total normal load. The additional changes are registered separately in the load fluctuation additional stress.

[0074] Furthermore, the current local contact stiffness corresponding to the tooth surface contact trajectory points that participate in contact at the same meshing moment is read, and the total normal load is allocated according to the proportion of the current local contact stiffness to the sum of the local contact stiffness of all tooth surface contact trajectory points that participate in contact at the same meshing moment.

[0075] Specifically, the distribution of normal loads is expressed as:

[0076] ;

[0077] in, Indicates the first The tooth surface contact trajectory point is at the first The first load calculation segment and the first Distributed normal load at each engagement moment Indicates the first The first load calculation segment and the first Total normal load at each engagement moment Indicates the first The tooth surface contact trajectory point is at the first The current local contact stiffness used in each load calculation segment Indicates the first The first load calculation segment and the first The set of tooth surface contact trajectory points that participate in contact at each meshing moment. Represents a set Inner The tooth surface contact trajectory point is at the first The current local contact stiffness used in each load calculation segment Indicates the number of the contact trajectory point on the tooth surface. Represents a set Numbering of contact trajectory points on the internal tooth surface Indicates the load calculation section number. Indicates the engagement moment number.

[0078] Based on the distributed normal load, the normal contact stress of the tooth surface is calculated. Combined with the friction coefficient, rolling ratio, sliding direction, load fluctuation data consisting of start-stop load, impact load and reverse load in the current load calculation segment, and temperature data, the tooth surface friction shear stress, load fluctuation additional stress and tooth surface thermal stress are calculated.

[0079] The tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress are regarded as five types of multi-stress components. They are synchronously registered according to the same tooth surface evaluation point, the same load calculation segment, and the same meshing time, and a multi-stress synchronous component record of the current load calculation segment is generated.

[0080] Furthermore, the normal contact stress on the tooth surface is calculated based on the distributed normal load.

[0081] Specifically, the distributed normal load is mapped to each deep tooth surface evaluation point under the same tooth surface contact trajectory point. The tooth surface curvature, tooth surface normal vector, material elastic modulus, and material Poisson's ratio of the evaluation points are read. The surface contact pressure of the tooth surface is calculated using Hertzian contact pressure. The depth stress of the elastic half-space is used to calculate the diameter. The tooth surface normal contact stress corresponding to the evaluation point is calculated along the depth direction. The tooth surface normal contact stress is registered in the evaluation point record.

[0082] Furthermore, based on the normal contact stress of the tooth surface, the frictional shear stress of the tooth surface is calculated.

[0083] Specifically, the friction coefficient, sliding ratio, and sliding direction at the current meshing moment are read, the tooth surface normal contact stress is converted into the tangential action of the tooth surface contact interface, the effective participation of the tangential action is corrected by the sliding ratio, and the sliding direction is projected onto the tooth surface tangential vector direction to obtain the tooth surface friction shear stress corresponding to the evaluation point.

[0084] The time interval of the tooth surface friction shear stress is recorded as the time interval between the point participating in the evaluation entering contact from the meshing position and leaving contact from the disengagement position; the direction of the tooth surface friction shear stress is recorded synchronously with the sliding direction.

[0085] Furthermore, based on the start-stop load, impact load, and reverse load within the current load calculation segment, the additional stress due to load fluctuation is calculated.

[0086] Specifically, the load fluctuation data within the current load calculation segment is read, and the occurrence time and action time interval of the start-stop load, impact load, and reverse load in the load fluctuation data are read. The additional stress of the start-stop load, impact load, and reverse load are calculated according to the same calculation caliber as the tooth surface normal contact stress. The additional stress of the start-stop load, impact load, and reverse load are merged and registered as the additional stress of load fluctuation. The start-stop load, impact load, and reverse load only participate in the calculation of the additional stress of load fluctuation within the action time interval registered in the running load data, and do not extend to the meshing time in the unregistered action time interval.

[0087] Furthermore, based on the tooth surface temperature and meshing flash temperature, the thermal stress on the tooth surface is calculated.

[0088] Specifically, the tooth surface temperature at the start of meshing in the current load calculation segment is used as the temperature source reference for the current load calculation segment; the tooth surface temperature and meshing flash temperature at the current meshing moment are read, and the temperature change relative to the temperature source reference at the current meshing moment is calculated; combined with the material's elastic modulus, material Poisson's ratio, and material thermal expansion coefficient, tooth surface thermal stress is generated.

[0089] Specifically, the thermal stress on the tooth surface is expressed as:

[0090] ;

[0091] in, Indicates the first The tooth surface evaluation point is at the first The first load calculation segment and the first Thermal stress on the tooth surface at each meshing moment Indicates the first The evaluation point on each tooth surface corresponds to the material's elastic modulus. Indicates the first The evaluation points on each tooth surface correspond to the material's coefficient of thermal expansion. Indicates the first The first load calculation segment and the first The tooth surface temperature at each meshing moment Indicates the first The first load calculation segment and the first Meshing flash temperature at each meshing moment, Indicates the first The tooth surface temperature at the initial engagement moment of each load calculation segment. Indicates the first Each evaluation point on the tooth surface corresponds to the Poisson's ratio of the material. Indicates the evaluation point number on the tooth surface, superscript This represents the thermal stress component on the tooth surface.

[0092] It should be noted that the unit of tooth surface thermal stress is Pascal. The sign of tooth surface thermal stress is determined by the direction of temperature change. When the sum of the tooth surface temperature and the meshing flash temperature at the current meshing moment is equal to the temperature source reference, the tooth surface thermal stress is zero. The time interval of tooth surface thermal stress is registered as the time interval covered by the temperature data sampling moment.

[0093] Furthermore, the current residual stress is read and recorded in the evaluation point record.

[0094] Specifically, the current residual stress is read according to the layer depth and material grade of the evaluation point; the current residual stress of the first load calculation segment is obtained from the basic data of gear contact fatigue assessment; the current residual stress of subsequent load calculation segments is obtained from the residual stress update record generated after the end of the previous load calculation segment.

[0095] It should be noted that the current residual stress is registered according to the layer depth of the evaluation point, and is not combined with the peak values ​​of the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, or tooth surface thermal stress.

[0096] Furthermore, by binding the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress, a multi-stress synchronous component record is generated.

[0097] Specifically, the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress are registered as five types of multi-stress components. Synchronous registration units are established according to the same tooth surface evaluation point, the same load calculation segment, and the same meshing time. The five types of multi-stress components, the time interval of action, the load calculation segment number, the meshing time, the layer depth position, and the tooth surface contact trajectory point in the evaluation point record are uniformly registered to generate the multi-stress synchronous component record of the current load calculation segment.

[0098] It should be noted that the multi-stress synchronous component record registers the source type of tooth surface normal contact stress, the source type of load fluctuation additional stress, the time interval of load fluctuation additional stress, the time interval of tooth surface thermal stress, and the current source type of residual stress. The source type of tooth surface normal contact stress is the torque data and gear geometry record at the current meshing moment. The source type of load fluctuation additional stress is start-stop load, impact load, or reverse load. The current source type of residual stress includes the source of basic data for gear contact fatigue assessment and the source of residual stress update records.

[0099] S3. Based on the multi-stress synchronous component record, extract the tooth surface normal contact stress history, generate an effective fatigue cycle record, screen synchronously participating stresses, form an effective fatigue cycle damage record, calculate the cumulative amount of residual stress relaxation, update the initial residual stress of the next load calculation segment, and generate a residual stress update record.

[0100] The stress history record of the current load calculation segment is formed by collecting five types of multi-stress components from the same tooth surface evaluation point and the same load calculation segment in the multi-stress synchronous component record, and combining the correspondence between the tooth surface evaluation point and the layer depth evaluation record.

[0101] Based on the stress history record, the normal contact stress history of the tooth surface is extracted in chronological order of engagement time. The contact cycle is divided by engagement and disengagement time to generate an effective fatigue cycle record.

[0102] Furthermore, the system reads the multi-stress synchronous component records, gear contact fatigue assessment basic data, material fatigue data, residual stress relaxation calibration data, and residual stress relaxation cumulative amount of the current load calculation segment. According to the tooth surface evaluation point and load calculation segment number, the system organizes the multi-stress synchronous component records and generates the stress history record of the current load calculation segment.

[0103] The multi-stress synchronous component record includes tooth surface evaluation points, load calculation segments, meshing time, tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, current residual stress, and the time interval of each stress component. The gear contact fatigue assessment basic data provides the correspondence between tooth surface evaluation points and layer depth evaluation records, material grade, heat treatment identification, surface treatment identification, and layer depth location.

[0104] Furthermore, based on the stress history record, the normal contact stress history of the tooth surface is extracted.

[0105] Specifically, the tooth surface normal contact stress at the same tooth surface evaluation point is read in the order of engagement time. The engagement time when the tooth surface evaluation point enters the tooth surface contact trajectory point is recorded as the cycle start time, and the engagement time when the tooth surface evaluation point leaves the tooth surface contact trajectory point is recorded as the cycle end time. The tooth surface normal contact stress sequence between the cycle start time and the cycle end time is recorded as the effective fatigue cycle.

[0106] It should be noted that when the same tooth surface evaluation point enters and leaves the tooth surface contact trajectory point multiple times within the current load calculation segment, effective fatigue cycles are generated one by one according to the order of meshing time.

[0107] The effective fatigue cycle record includes tooth surface evaluation points, load calculation segments, cycle start time, cycle end time, cycle start meshing cycle number, cycle end meshing cycle number, tooth surface contact trajectory points, corresponding meshing positions of tooth surface contact trajectory points, and tooth surface normal contact stress history.

[0108] Based on effective fatigue cycle records, the time intervals of tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress are compared to screen synchronously involved stresses and generate synchronously involved stress records and segmented effective fatigue cycle records.

[0109] Furthermore, based on the effective fatigue cycle records, and according to the coverage relationship between the action time interval and the effective fatigue cycle time interval, synchronously participating stresses are screened.

[0110] Specifically, the start and end times of each effective fatigue cycle are read to form the effective fatigue cycle time interval, and the time intervals of the tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress are read.

[0111] When the time interval of action covers the period from the start of the cycle to the end of the cycle, the corresponding stress is registered as a synchronously participating stress.

[0112] When the time interval of action has not entered the cycle from the start time to the end time, the corresponding stress will be registered as a traceable stress.

[0113] When the time interval of action partially overlaps with the time from the start to the end of the cycle, the effective fatigue cycle is divided into segmented effective fatigue cycles according to the overlap boundary. The stress corresponding to the overlapping time interval is registered as synchronously participating stress, and the cycle start meshing cycle number and cycle end meshing cycle number of the effective fatigue cycle are registered in the segmented effective fatigue cycle record.

[0114] The current residual stress is registered as the layer depth stress state that continues to exist in the current load calculation segment according to the layer depth position of the tooth surface evaluation point. The current residual stress covers the effective fatigue cycle and segmented effective fatigue cycle formed by the corresponding tooth surface evaluation point in the current load calculation segment.

[0115] After completing all effective fatigue cycle processing, synchronous stress records and segmented effective fatigue cycle records are generated.

[0116] By simultaneously participating in stress recording and segmented effective fatigue cycle recording, a local coordinate system for the tooth surface is established. The tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress are mapped into a three-dimensional stress tensor to form a multiaxial stress state. The maximum shear stress amplitude, the average hydrostatic stress, and the number of cycles that can be withstood are obtained. Based on the cycle start meshing cycle number, cycle end meshing cycle number, and the number of load spectrum repetitions in the load calculation segment record corresponding to the effective fatigue cycle record or segmented effective fatigue cycle record, the actual number of cycles is generated, and the effective fatigue cycle damage record is obtained.

[0117] Furthermore, fatigue cycle evaluation data are obtained based on the synchronous stress recording.

[0118] Specifically, the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress within the same effective fatigue cycle or the same segmented effective fatigue cycle are read. The tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress synchronously participating in the stress record are taken as five types of multi-stress components participating in fatigue calculation. A local coordinate system of the tooth surface is established according to the same tooth surface evaluation point, the same load calculation segment, and the same meshing time, and combined to form a multiaxial stress state.

[0119] Specifically, the local coordinate system of the tooth surface uses the direction of the tooth surface tangent vector as... Shaft, with the tooth width direction as The axis is defined by pointing the tooth surface normal vector towards the layer depth direction. The axis; the tooth width direction is determined according to the tooth surface normal vector and tooth surface tangent vector; compressive stress is recorded as negative values, tensile stress is recorded as positive values, and the sign of tooth surface friction shear stress is recorded according to the sliding direction.

[0120] The maximum shear stress amplitude and mean hydrostatic stress corresponding to the effective fatigue cycle or segmented effective fatigue cycle are calculated by using the three-dimensional stress tensor principal stress transformation method.

[0121] Specifically, multiaxial stress states are read at the same tooth surface evaluation point, the same load calculation segment, and the same meshing moment, and a three-dimensional stress tensor is generated in the local coordinate system of the tooth surface; the three-dimensional stress tensor includes , , , , as well as Six components; tooth surface thermal stress and current residual stress are written simultaneously. Components and The components, the superposition of tooth surface normal contact stress and load fluctuation additional stress, are written into the equation. Components, tooth surface friction shear stress as Components are written into the three-dimensional stress tensor. Components and The components are registered as zero values; after completing the registration of the six components, the first principal stress, the second principal stress, and the third principal stress corresponding to the three-dimensional stress tensor are solved.

[0122] The first, second, and third principal stresses are arranged in descending order of value. The maximum shear stress at each meshing moment is taken as half the difference between the first and third principal stresses. The maximum shear stress amplitude corresponding to an effective fatigue cycle or segmented effective fatigue cycle is taken as half the difference between the maximum and minimum values ​​in the maximum shear stress sequence. The hydrostatic stress at each meshing moment is taken as the arithmetic mean of the first, second, and third principal stresses. The mean hydrostatic stress corresponding to an effective fatigue cycle or segmented effective fatigue cycle is taken as the arithmetic mean of the hydrostatic stress sequence. The tooth surface local coordinate system, three-dimensional stress tensor components, maximum shear stress amplitude, mean hydrostatic stress, material grade, layer depth, heat treatment markings, and surface treatment markings are registered as fatigue cycle evaluation data.

[0123] It should be noted that the maximum shear stress amplitude characterizes the shear fatigue effect in the effective fatigue cycle or segmented effective fatigue cycle, while the average hydrostatic stress characterizes the average normal stress effect in the effective fatigue cycle or segmented effective fatigue cycle.

[0124] It should be noted that the multiaxial stress state is formed only by the five types of multi-stress components registered at the same tooth surface evaluation point, the same load calculation segment, and the same meshing time. The three-dimensional stress tensor is generated only according to the six components of the local coordinate system of the tooth surface. Stress sources not registered in the six components do not participate in the principal stress transformation. Stress peaks at different meshing times are not merged. The principal stress transformation of the three-dimensional stress tensor is only performed within the multiaxial stress state corresponding to the same meshing time, and the principal stress transformation is not performed after extracting the peak value across meshing times.

[0125] Furthermore, based on fatigue cycle evaluation data, the number of cycles that can be withstood is determined.

[0126] Specifically, the number of cycles that can be withstood is read from the material fatigue data according to the material grade, layer depth, maximum shear stress amplitude, and average hydrostatic stress.

[0127] When the maximum shear stress amplitude and the average hydrostatic stress are completely consistent with the measured fatigue data in the material fatigue data, the corresponding number of cycles that can be withstood is read.

[0128] When the maximum shear stress amplitude and the mean hydrostatic stress are located between adjacent measured fatigue data, four adjacent measured fatigue data surrounding the maximum shear stress amplitude and the mean hydrostatic stress are read. The number of cycles that can withstand in the four adjacent measured fatigue data is taken as the common logarithm. Logarithmic bilinear interpolation is performed according to the direction of the maximum shear stress amplitude and the direction of the mean hydrostatic stress. The interpolation result is then subjected to exponential restoration to base 10 to generate the number of cycles that can withstand.

[0129] When the maximum shear stress amplitude is consistent with the measured maximum shear stress amplitude in the material fatigue data and the mean hydrostatic stress is between adjacent measured mean hydrostatic stress values, take the common logarithm of the tolerable cycle number and perform linear interpolation along the direction of the mean hydrostatic stress. Then, perform exponential restoration to base 10 on the interpolation result to generate the tolerable cycle number.

[0130] When the mean hydrostatic stress is consistent with the mean hydrostatic stress in the material fatigue data and the maximum shear stress amplitude is between adjacent measured maximum shear stress amplitudes, take the common logarithm of the tolerable cycle number and then perform linear interpolation along the direction of the maximum shear stress amplitude. Perform exponential restoration to base 10 on the interpolation result to generate the tolerable cycle number.

[0131] It should be noted that when the maximum shear stress amplitude or the average hydrostatic stress exceeds the coverage range of the material fatigue data, the fatigue damage increment corresponding to the effective fatigue cycle is not generated, and an abnormal record of material fatigue data coverage is registered; a record of the number of cycles that can be withstood is generated.

[0132] Furthermore, based on the effective fatigue cycle records, segmented effective fatigue cycle records, and load calculation segment records, an actual cycle count record is generated.

[0133] Specifically, the cycle start engagement cycle number and cycle end engagement cycle number in the effective fatigue cycle record or segmented effective fatigue cycle record are read to determine the number of engagement cycles covered by the effective fatigue cycle or segmented effective fatigue cycle; the load spectrum repetition count in the load calculation segment record is read, and the number of engagement cycles is multiplied by the load spectrum repetition count to generate the actual number of cycles; when a single engagement to disengagement contact cycle corresponds to one engagement cycle, the actual number of cycles is equal to the load spectrum repetition count.

[0134] It should be noted that the cycle start and cycle end numbers in the segmented effective fatigue cycle record are determined by the corresponding effective fatigue cycle record; the actual number of cycles is linked to the tooth surface evaluation point, load calculation segment, effective fatigue cycle or segmented effective fatigue cycle to generate the actual number of cycles record.

[0135] Furthermore, the fatigue damage increment is calculated based on the number of cycles that can be tolerated.

[0136] Specifically, the actual number of cycles corresponding to the effective fatigue cycle or segmented effective fatigue cycle is read, the tolerable number of cycles in the tolerable number of cycles record is read, and the actual number of cycles and the tolerable number of cycles are converted into cycle damage to generate fatigue damage increment.

[0137] Specifically, the fatigue damage increment is expressed as:

[0138] ;

[0139] in, Indicates the first The tooth surface evaluation point is at the first The fatigue damage increment corresponding to an effective fatigue cycle or segmented effective fatigue cycles. This indicates the effective fatigue cycle or segmented effective fatigue cycle number. Indicates the first The actual number of cycles corresponding to an effective fatigue cycle or a segmented effective fatigue cycle. Indicates the first The tooth surface evaluation point is at the first The number of cycles that can be withstood corresponds to an effective fatigue cycle or a segmented effective fatigue cycle.

[0140] It should be noted that the fatigue damage increment is formed by the ratio of the actual number of cycles corresponding to the effective fatigue cycle or segmented effective fatigue cycle to the number of cycles that the material can withstand, thus forming the damage contribution of a single effective fatigue cycle or segmented effective fatigue cycle. The fatigue damage increment is recorded together with the tooth surface evaluation point, load calculation segment, effective fatigue cycle or segmented effective fatigue cycle, synchronous stress, maximum shear stress amplitude, average hydrostatic stress, actual number of cycles, and the number of cycles that can withstand, forming an effective fatigue cycle damage record.

[0141] Based on effective fatigue cycle damage records, combined with temperature data and actual number of cycles, the cumulative amount of residual stress relaxation is calculated, the residual stress relaxation calibration data is matched, the initial residual stress of the next load calculation segment is updated, and the residual stress update record is generated.

[0142] Furthermore, based on the effective fatigue cycle damage records and temperature data, the cumulative amount of residual stress relaxation is calculated.

[0143] Specifically, the effective fatigue cycles and segmented effective fatigue cycles are read, and a set of effective fatigue cycles is established according to the order of cycles within the load calculation segment; the maximum shear stress amplitude, actual number of cycles, and temperature data corresponding to each effective fatigue cycle or segmented effective fatigue cycle are read.

[0144] It should be noted that when the tooth surface temperature in the temperature data is an absolute temperature, the tooth surface temperature is read directly; when the tooth surface temperature in the temperature data is a Celsius temperature, the Celsius temperature is converted to an absolute temperature according to the thermodynamic temperature conversion rules; when the meshing flash temperature is a temperature rise, the meshing flash temperature is converted to the same temperature unit and then incorporated into the tooth surface absolute temperature to obtain the absolute temperature corresponding to the effective fatigue cycle.

[0145] Furthermore, the residual stress relaxation accumulation is generated by discretely accumulating the effective fatigue cycle set after the end of the current load calculation segment.

[0146] Specifically, the cumulative amount of residual stress relaxation after the current load calculation segment ends is expressed as:

[0147] ;

[0148] in, Indicates the first The tooth surface evaluation point is at the first The cumulative amount of residual stress relaxation after the end of each load calculation segment. Indicates the first The tooth surface evaluation point is at the first The cumulative amount of residual stress relaxation after the end of each load calculation segment. Indicates the first The tooth surface evaluation point is at the first The effective fatigue cycles formed within each load calculation segment and the set of segmented effective fatigue cycles. Indicates the first The tooth surface evaluation point is at the first The maximum shear stress corresponding to a single effective fatigue cycle or a segmented effective fatigue cycle. Indicates the first The tooth surface evaluation point is at the first The absolute temperature corresponding to an effective fatigue cycle or a segmented effective fatigue cycle.

[0149] It should be noted that the residual stress relaxation calibration data are calculated by multiplying the maximum shear stress amplitude, absolute temperature, and number of cycles under the same material, heat treatment, surface treatment, and layer depth conditions to form the cumulative residual stress relaxation amount. The same cumulative caliber is used in the current load calculation segment.

[0150] Furthermore, the initial residual stress for the next load calculation segment is updated based on the cumulative amount of residual stress relaxation.

[0151] Specifically, residual stress relaxation calibration data are read according to the material grade, heat treatment mark, surface treatment mark, and layer depth position corresponding to the evaluation point on the tooth surface. The residual stress relaxation calibration data comes from the residual stress detection data under the same material, heat treatment, surface treatment, and layer depth position. The residual stress relaxation calibration data is registered from the point where no relaxation state has been experienced, and the cumulative amount of residual stress relaxation corresponding to the point where no relaxation state has been experienced is zero. The cumulative amount of residual stress relaxation in the residual stress relaxation calibration data is arranged in ascending order according to the measured sequence.

[0152] Read the cumulative residual stress relaxation after the end of the current load calculation segment, and find the two adjacent residual stress relaxation calibration data that surround the current cumulative residual stress relaxation. When the current cumulative residual stress relaxation is equal to the cumulative residual stress relaxation in a certain residual stress relaxation calibration data, directly read the corresponding residual stress. When the current cumulative residual stress relaxation is located between two adjacent residual stress relaxation calibration data, use the two adjacent residual stress relaxation calibration data to perform interpolation to obtain the initial residual stress of the next load calculation segment.

[0153] Specifically, the initial residual stress in the next load calculation segment is expressed as:

[0154] ;

[0155] in, Indicates the first The tooth surface evaluation point is used for the first The initial residual stress of each load calculation segment, superscript Represents the residual stress components. Indicates the first The evaluation point on the tooth surface corresponds to the residual stress relaxation calibration data of the [number]th [item]. The residual stress recorded in the calibration record, Indicates the first The evaluation point on the tooth surface corresponds to the residual stress relaxation calibration data of the [number]th [item]. The residual stress recorded in the calibration record, Indicates the first The evaluation point on the tooth surface corresponds to the residual stress relaxation calibration data of the [number]th [item]. The cumulative amount of residual stress relaxation recorded in the calibration log. Indicates the first The evaluation point on the tooth surface corresponds to the residual stress relaxation calibration data of the [number]th [item]. The cumulative amount of residual stress relaxation recorded in the calibration log. Indicates satisfaction The calibration record number.

[0156] It should be noted that the cumulative residual stress relaxation values ​​in the residual stress relaxation calibration data are arranged in ascending order and satisfy the following conditions: ;when When the maximum acquisition coverage position of the residual stress relaxation calibration data is reached, read the residual stress corresponding to the maximum acquisition coverage position; when When the residual stress relaxation calibration data exceeds the maximum acquisition coverage position, the residual stress corresponding to the maximum acquisition coverage position is used, and extrapolation is not performed; the maximum acquisition coverage position is the measured range of the residual stress relaxation calibration data.

[0157] Furthermore, a residual stress update record is generated. Specifically, the tooth surface evaluation point, the current load calculation segment, the next load calculation segment, the cumulative amount of residual stress relaxation, the initial residual stress of the next load calculation segment, the material grade, the heat treatment identifier, the surface treatment identifier, and the layer depth position are bound together to form a residual stress update record.

[0158] S4. Read the effective fatigue cycle damage record and residual stress update record, generate the cumulative fatigue damage record, compare the cumulative fatigue damage record with the cumulative damage value at fatigue termination, update the initial local contact stiffness of the next load calculation segment in the non-termination state, generate the input record of the next load calculation segment, and either return the input record of the next load calculation segment or output the gear contact fatigue life assessment result.

[0159] Collect effective fatigue cycle damage records, accumulate fatigue damage increments according to the tooth surface evaluation points and load calculation segment numbers, and generate cumulative fatigue damage records.

[0160] Furthermore, the effective fatigue cycle damage record and residual stress update record are read, and the tooth surface evaluation point, load calculation segment, local contact stiffness calibration data, cumulative fatigue damage, and cumulative damage value at fatigue termination are also read.

[0161] The effective fatigue cycle damage record includes the tooth surface evaluation point, load calculation segment, effective fatigue cycle or segmented effective fatigue cycle, synchronously involved stress, maximum shear stress amplitude, average hydrostatic stress, actual number of cycles, tolerable number of cycles, and fatigue damage increment; the residual stress update record includes the tooth surface evaluation point, current load calculation segment, next load calculation segment, cumulative residual stress relaxation, and initial residual stress of the next load calculation segment.

[0162] Furthermore, based on the tooth surface evaluation points and load calculation segment numbers, effective fatigue cycle damage records are collected to generate damage collection records for the current load calculation segment.

[0163] Furthermore, based on the damage collection record of the current load calculation segment, according to the order of effective fatigue cycles or segmented effective fatigue cycles within the current load calculation segment, the cumulative fatigue damage increment is accumulated to generate the cumulative fatigue damage after the end of the current load calculation segment.

[0164] Specifically, the cumulative fatigue damage at the end of the current load calculation segment is expressed as:

[0165] ;

[0166] in, Indicates the first The tooth surface evaluation point is at the first The cumulative fatigue damage after the end of each load calculation segment. Indicates the first The tooth surface evaluation point is at the first The cumulative fatigue damage after the end of each load calculation segment.

[0167] It should be noted that the cumulative fatigue damage value may increase or remain unchanged as the fatigue damage increment accumulates. After the cumulative fatigue damage is calculated, a cumulative fatigue damage record is generated. The cumulative fatigue damage record includes the tooth surface evaluation point, the current load calculation segment, the effective fatigue cycle set, the fatigue damage increment, and the cumulative fatigue damage.

[0168] Compare the cumulative fatigue damage record with the cumulative fatigue termination damage value. When the cumulative fatigue termination damage value is reached, generate a life termination candidate record. When the cumulative fatigue termination damage value is not reached, register the non-termination status.

[0169] Furthermore, the cumulative fatigue damage record is compared with the cumulative fatigue termination value. Specifically, the cumulative fatigue termination value corresponding to each tooth surface evaluation point is read. When the cumulative fatigue damage after the end of the current load calculation segment does not reach the cumulative fatigue termination value of the corresponding tooth surface evaluation point, the non-termination state is registered and the local contact stiffness is updated.

[0170] When the cumulative fatigue damage after the current load calculation segment ends reaches the cumulative fatigue termination damage value of the corresponding tooth surface evaluation point, a life termination candidate record is registered.

[0171] Among them, the candidate records for the end of life include the tooth surface evaluation point, the current load calculation segment, the effective fatigue cycle or segmented effective fatigue cycle that reaches the cumulative damage value at the end of fatigue, the cumulative fatigue damage, the cumulative damage value at the end of fatigue, and the corresponding meshing time.

[0172] Based on the cumulative fatigue damage record corresponding to the unterminated state, the cumulative fatigue damage corresponding to the tooth surface evaluation point is collected according to the tooth surface contact trajectory point, and the equivalent cumulative fatigue damage of the tooth surface contact trajectory point is generated. The local contact stiffness calibration data corresponding to the tooth surface contact trajectory point is read and matched. The initial local contact stiffness of the next load calculation segment is updated according to the equivalent cumulative fatigue damage of the tooth surface contact trajectory point. Combined with the residual stress update record, the initial local contact stiffness of the next load calculation segment corresponding to the tooth surface contact trajectory point and the initial residual stress of the next load calculation segment corresponding to the tooth surface evaluation point are bound together to generate the input record of the next load calculation segment.

[0173] If no candidate record for end of life is generated and there is a next load calculation segment, the input record for the next load calculation segment is reflowed. If no candidate record for end of life is generated and there is no next load calculation segment, an evaluation result that has not been terminated is generated.

[0174] Furthermore, when no candidate records for the end of life are registered, the initial local contact stiffness of the next load calculation segment is updated based on the cumulative fatigue damage records.

[0175] Specifically, local contact stiffness calibration data is read according to the tooth surface contact trajectory points. The local contact stiffness calibration data includes the tooth surface contact trajectory points, the cumulative fatigue damage state, and the corresponding local contact stiffness. The local contact stiffness calibration data corresponding to the same tooth surface contact trajectory point are arranged from low to high according to the cumulative fatigue damage state. The cumulative fatigue damage record after the end of the current load calculation segment is read. According to the same tooth surface contact trajectory point, the cumulative fatigue damage corresponding to the tooth surface evaluation point is collected to generate the equivalent cumulative fatigue damage of the tooth surface contact trajectory point.

[0176] Specifically, the equivalent cumulative fatigue damage at the tooth surface contact trajectory point is expressed as:

[0177] ;

[0178] in, Indicates the first The tooth surface contact trajectory point is at the first The equivalent cumulative fatigue damage at the tooth surface contact trajectory points after the end of each load calculation segment. Indicates the first A set of tooth surface evaluation points bound to each tooth surface contact trajectory point.

[0179] When the equivalent cumulative fatigue damage at the current tooth surface contact trajectory point is equal to the cumulative fatigue damage state in a certain local contact stiffness calibration data, the local contact stiffness corresponding to the tooth surface contact trajectory point is read.

[0180] When the equivalent cumulative fatigue damage of the current tooth surface contact trajectory point is located between two adjacent local contact stiffness calibration data, linear interpolation is performed to obtain the initial local contact stiffness of the next load calculation segment corresponding to the tooth surface contact trajectory point.

[0181] Specifically, the initial local contact stiffness of the next load calculation segment is expressed as:

[0182] ;

[0183] in, Indicates the first The tooth surface contact trajectory point is used for the first Initial local contact stiffness of each load calculation segment, Indicates the first The local contact stiffness calibration data corresponding to the contact trajectory point of the tooth surface is the first one. The local contact stiffness of the calibration record, Indicates the first The local contact stiffness calibration data corresponding to the contact trajectory point of the tooth surface is the first one. The local contact stiffness of the calibration record, Indicates the first The local contact stiffness calibration data corresponding to the contact trajectory point of the tooth surface is the first one. The cumulative fatigue damage status recorded in the calibration records. Indicates the first The local contact stiffness calibration data corresponding to the contact trajectory point of the tooth surface is the first one. The cumulative fatigue damage status recorded in the calibration records. Indicates satisfaction The calibration record number.

[0184] It should be noted that the cumulative fatigue damage state in the local contact stiffness calibration data is arranged in ascending order according to the measured or calculated calibration, satisfying the following conditions: The initial local contact stiffness value for the next load calculation segment is located at... and between.

[0185] It should be noted that when the equivalent cumulative fatigue damage of the current tooth surface contact trajectory point reaches the maximum acquisition coverage position of the local contact stiffness calibration data, the local contact stiffness corresponding to the maximum acquisition coverage position is read; when the equivalent cumulative fatigue damage of the current tooth surface contact trajectory point exceeds the maximum acquisition coverage position of the local contact stiffness calibration data and is in an unterminated state, the local contact stiffness corresponding to the maximum acquisition coverage position is used, and extrapolation is not performed; the maximum acquisition coverage position is determined by the measured or calculated calibration coverage range of the local contact stiffness calibration data; a local contact stiffness update record is generated.

[0186] The local contact stiffness update record includes the tooth surface contact trajectory point, the current load calculation segment, the next load calculation segment, the equivalent cumulative fatigue damage of the tooth surface contact trajectory point, the initial local contact stiffness of the next load calculation segment, and the source of local contact stiffness calibration data.

[0187] Furthermore, the local contact stiffness update record is bound to the residual stress update record to generate the input record for the next load calculation segment.

[0188] Specifically, according to the tooth surface evaluation point, tooth surface contact trajectory point, and next load calculation segment number, the initial residual stress of the next load calculation segment in the residual stress update record, the initial local contact stiffness of the next load calculation segment corresponding to the tooth surface contact trajectory point, the cumulative fatigue damage in the cumulative fatigue damage record, and the cumulative amount of residual stress relaxation are bound to the same tooth surface evaluation point, the same tooth surface contact trajectory point, and the same next load calculation segment to generate the next load calculation segment input record.

[0189] The input records for the next load calculation segment include the tooth surface evaluation point, tooth surface contact trajectory point, next load calculation segment, initial residual stress of the next load calculation segment, initial local contact stiffness of the next load calculation segment corresponding to the tooth surface contact trajectory point, cumulative fatigue damage, and cumulative residual stress relaxation.

[0190] Furthermore, it is determined whether there is a next load calculation segment after the current load calculation segment.

[0191] If there is a load calculation segment in the load calculation segment record that is ordered after the current load calculation segment, then the input record of the next load calculation segment is read, the next load calculation segment is registered as the new current load calculation segment, the initial residual stress of the next load calculation segment is registered as the current residual stress of the new current load calculation segment, the initial local contact stiffness of the next load calculation segment corresponding to the tooth surface contact trajectory point is registered as the current local contact stiffness of the new current load calculation segment, and combined with the service data and tooth surface contact trajectory points of the new current load calculation segment, the meshing time sequence is reorganized, the evaluation points are determined, the total normal load is allocated, and the multi-stress synchronous component record of the new current load calculation segment is generated.

[0192] If there is no load calculation segment in the load calculation segment record that is ordered after the current load calculation segment, and no candidate record for life termination is registered, then an evaluation result that has not been terminated is generated.

[0193] The results of the unterminated evaluation include the range of the calculated load segment, the cumulative fatigue damage at each tooth surface evaluation point, the current residual stress, the cumulative amount of residual stress relaxation, the current local contact stiffness at each tooth surface contact trajectory point, and the tooth surface evaluation point closest to the cumulative damage value at fatigue termination.

[0194] Among them, the tooth surface evaluation point closest to the cumulative damage value at the end of fatigue is obtained by comparing the difference between the cumulative damage value at the end of fatigue and the cumulative fatigue damage at each tooth surface evaluation point. The tooth surface evaluation point with the smallest difference is registered as the tooth surface evaluation point closest to the cumulative damage value at the end of fatigue. The difference is determined by the cumulative fatigue damage record and the cumulative damage value at the end of fatigue.

[0195] When generating candidate records for the end of life, the fatigue hazard location is determined, and life tracing records and gear contact fatigue life assessment results are generated.

[0196] Furthermore, when registering candidate records for the end of life, the candidate records for the end of life are sorted according to the load calculation segment number and the order of effective fatigue cycles or segmented effective fatigue cycles, and the tooth surface evaluation point that reaches the cumulative damage value of fatigue termination earliest is selected as the fatigue danger location.

[0197] Fatigue-prone locations include the three-dimensional coordinates of the tooth surface, tooth height, tooth width, layer depth, tooth surface contact trajectory point, corresponding meshing position of the tooth surface contact trajectory point, current load calculation segment, effective fatigue cycle or segmented effective fatigue cycle, cycle start time, and cycle end time.

[0198] Furthermore, the effective fatigue cycle damage record, residual stress update record, and local contact stiffness update record corresponding to the fatigue danger location are read to generate a life traceability record.

[0199] The life tracking record includes synchronous stress, maximum shear stress amplitude, average hydrostatic stress, number of cycles that can be withstood, fatigue damage increment, cumulative fatigue damage, current residual stress, current local contact stiffness, and cumulative residual stress relaxation.

[0200] Furthermore, based on the candidate life termination records, load calculation segment records, and effective fatigue cycle damage records, gear contact fatigue life assessment results are generated.

[0201] Specifically, based on the load calculation segment number that reaches the earliest cumulative damage value at fatigue termination and the effective fatigue cycle or segmented effective fatigue cycle, the actual number of cycles in the corresponding effective fatigue cycle damage record is read. According to the load calculation segment number and the order of the effective fatigue cycle or segmented effective fatigue cycle, the number of cycles is accumulated to the effective fatigue cycle or segmented effective fatigue cycle that reaches the earliest cumulative damage value at fatigue termination, thus generating the gear contact fatigue life cycle number.

[0202] Read the service time range of the corresponding load calculation segment and the meshing time corresponding to the effective fatigue cycle to generate the gear contact fatigue life time.

[0203] It should be noted that the gear contact fatigue life assessment results include the number of gear contact fatigue life cycles, gear contact fatigue life time, fatigue danger location, danger layer depth, corresponding load calculation segment, corresponding effective fatigue cycles, residual stress update record, local contact stiffness update record, life traceability record, and cumulative fatigue damage curve.

[0204] It should be noted that when no candidate record for life termination is registered and a next load calculation segment exists, the input record of the next load calculation segment is read, the next load calculation segment is registered as a new current load calculation segment, the current residual stress and current local contact stiffness are called, and combined with the service data of the new current load calculation segment and the corresponding tooth surface contact trajectory points, the multi-stress synchronous component record of the new current load calculation segment is generated; when a candidate record for life termination is registered, the gear contact fatigue life assessment result is output; when no candidate record for life termination is registered and there is no next load calculation segment, the non-termination assessment result is output.

[0205] Furthermore, the beneficial effects of this embodiment are verified through simulation experiments. Specifically, the simulation experiment is carried out in the continuous service scenario of the high-speed stage helical gear pair of the wind power speed increaser. The evaluation object is the helical gear pair composed of the driving gear and the driven gear. The gear geometric data, residual stress depth data, material fatigue data, residual stress relaxation calibration data and local contact stiffness calibration data are read to generate tooth surface contact trajectory records, layer depth evaluation records and tooth surface evaluation points.

[0206] Gear geometry data includes number of teeth, module, pressure angle, helix angle, tooth width, center distance, tooth surface contact trajectory points, and tooth surface curvature; the layer depth evaluation record includes layer depth location, initial residual stress, material grade, heat treatment marking, surface treatment marking, and source of cumulative damage value at fatigue termination.

[0207] The tooth surface contact trajectory was discretized into 18 tooth surface contact trajectory points, and the layer depth was set to 0 mm, 0.05 mm, 0.1 mm, 0.2 mm and 0.35 mm, forming 90 tooth surface evaluation points. The continuous service process was divided into 48 load calculation segments. Each load calculation segment recorded torque, speed, friction coefficient, rolling ratio, tooth surface temperature, meshing flash temperature, load fluctuation data and the number of load spectrum repetitions.

[0208] Based on the tooth surface evaluation points and load calculation segments, the following data are generated in accordance with the method described in this embodiment: multi-stress synchronous component record, effective fatigue cycle damage record, residual stress update record, cumulative fatigue damage record, equivalent cumulative fatigue damage record of tooth surface contact trajectory points, local contact stiffness update record, and gear contact fatigue life assessment result.

[0209] Figure 5 The simulation demonstrates the evolution of multiple stress components synchronously at a critical location, which is point five on the tooth surface contact trajectory with a layer depth of 0 mm. The simulation experiment sequentially reads torque, friction coefficient, rolling ratio, load fluctuation data, tooth surface temperature, and meshing flash temperature according to the load calculation segment number. Based on the distributed normal load, the normal contact stress of the tooth surface is calculated. Combining the friction coefficient and rolling ratio, the friction shear stress of the tooth surface is calculated. Combining the load fluctuation data composed of start-stop loads, impact loads, and reverse loads, the additional stress due to load fluctuations is calculated. Combining the tooth surface temperature and meshing flash temperature, the thermal stress of the tooth surface is calculated, and the current residual stress is simultaneously read.

[0210] The five types of multi-stress components are recorded in the multi-stress synchronous component record according to the same tooth surface evaluation point, the same load calculation segment, and the same meshing time. Figure 5The five curves correspond to the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress, respectively. The curves together reflect the multi-stress coupling state of the dangerous position during continuous service. The experimental results show that the multi-stress synchronous component recording can preserve the numerical source and evolution relationship of different multi-stress components at the same meshing moment, providing a traceable data basis for subsequent screening of synchronously involved stresses and forming effective fatigue cycle damage records.

[0211] Figure 6 The simulation demonstrates the update process of residual stress at different depths in the critical location, which is point five on the tooth surface contact trajectory. Within each load calculation segment, the simulation extracts the normal contact stress history of the tooth surface, divides the effective fatigue cycle records according to the engagement and disengagement times, compares the time intervals of tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress, filters out synchronously participating stresses, and forms an effective fatigue cycle damage record. The simulation then reads the effective fatigue cycle damage increment, temperature data, and actual number of cycles, calculates the cumulative amount of residual stress relaxation, matches the residual stress relaxation calibration data, and updates the initial residual stress for the next load calculation segment.

[0212] Figure 6 The five curves correspond to layer depths of 0 mm, 0.05 mm, 0.1 mm, 0.2 mm, and 0.35 mm, respectively. The curves show that the current residual stress in the surface layer is continuously updated in the direction of decreasing absolute value of residual compressive stress as the load calculation segment progresses. The update amplitude of the current residual stress in the deeper layer is constrained by both effective fatigue cycle damage and temperature data. Experimental results show that the method in this embodiment can establish a corresponding relationship between the effective fatigue cycle damage record, the cumulative amount of residual stress relaxation, and the current residual stress update record, realizing a continuous characterization of the evolution of residual stress during service.

[0213] In summary, this invention generates multi-stress synchronous component records to unify the tooth surface evaluation point, load calculation segment, and meshing moment at the tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress. It generates effective fatigue cycle records by extracting the tooth surface normal contact stress history, filters synchronously participating stresses, forms effective fatigue cycle damage records, and calculates the cumulative amount of residual stress relaxation, achieving a correspondence between effective fatigue cycle damage and the current residual stress update. Finally, it updates the initial local contact stiffness of the next load calculation segment and generates the input record for the next load calculation segment through the cumulative fatigue damage record, improving the traceability of gear contact fatigue life assessment results and the consistency of service evolution characterization.

[0214] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for gear contact fatigue life assessment considering multi-stress coupling, characterized in that, include: Read gear geometry data, residual stress depth data, material fatigue data, residual stress relaxation calibration data, and local contact stiffness calibration data; generate tooth surface contact trajectory records and layer depth evaluation records; bind them to form tooth surface evaluation points; register initial state data; and obtain basic data for gear contact fatigue assessment. Based on the basic data of gear contact fatigue assessment, the current load calculation segment is determined, the meshing time sequence is organized, the total normal load is allocated, five types of multi-stress components are calculated, and multi-stress synchronous component records are generated. Based on the multi-stress synchronous component record, the tooth surface normal contact stress history is extracted, an effective fatigue cycle record is generated, synchronously participating stresses are screened, an effective fatigue cycle damage record is formed, the cumulative amount of residual stress relaxation is calculated, the initial residual stress of the next load calculation segment is updated, and a residual stress update record is generated. Read the effective fatigue cycle damage record and residual stress update record, generate the cumulative fatigue damage record, compare the cumulative fatigue damage record with the cumulative damage value at fatigue termination, update the initial local contact stiffness of the next load calculation segment in the non-termination state, generate the input record of the next load calculation segment, if no life termination candidate record is generated but the next load calculation segment exists, backflow the input record of the next load calculation segment, if no life termination candidate record is generated and the next load calculation segment does not exist, generate the non-termination evaluation result; When generating candidate records for the end of life, the location of fatigue danger is determined, and life traceability records and gear contact fatigue life assessment results are generated. The generation of tooth surface contact trajectory records and layer depth evaluation records, and the binding of these records to form tooth surface evaluation points, include: Read the gear geometry data, determine the order of engagement, node and disengagement positions, organize the three-dimensional coordinates of the tooth surface along the meshing direction to form a gear geometry record, combine with the meshing motion relationship record, extract the three-dimensional coordinates of the tooth surface involved in the contact, and generate a tooth surface contact trajectory record. Based on residual stress depth data, material fatigue data, and residual stress relaxation calibration data, a layer depth evaluation record is established, and the tooth surface contact trajectory record is bound to the layer depth evaluation record to generate tooth surface evaluation points. The calculation of five types of multi-stress components and the binding of multi-stress synchronous component records include: Based on the distributed normal load, the normal contact stress of the tooth surface is calculated. Combined with the friction coefficient, the sliding-rolling ratio, the sliding direction, the load fluctuation data consisting of start-stop load, impact load and reverse load in the current load calculation segment, and the temperature data, the tooth surface friction shear stress, the load fluctuation additional stress and the tooth surface thermal stress are calculated. The tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress, and current residual stress are regarded as five types of multi-stress components. They are synchronously registered according to the same tooth surface evaluation point, the same load calculation segment, and the same meshing time, and a multi-stress synchronous component record of the current load calculation segment is generated.

2. The method for gear contact fatigue life assessment considering multi-stress coupling according to claim 1, characterized in that, The registration of initial state data, and the acquisition of basic data for gear contact fatigue assessment, include: Based on the tooth surface evaluation points, initial state data is registered, service process records are organized, load calculation segments are generated, and tooth surface evaluation points, load calculation segments, and initial state data are associated to generate basic data for gear contact fatigue assessment.

3. The gear contact fatigue life assessment method considering multi-stress coupling as described in claim 1, characterized in that, The process of determining the current load calculation segment, organizing the meshing time sequence, and allocating the total normal load based on gear contact fatigue assessment data includes: According to the load calculation segment number and the order of service time, the current load calculation segment is registered, and the meshing time sequence is generated by combining the start meshing cycle, the end meshing cycle, the sampling time and the tooth surface contact trajectory point; Based on the tooth surface contact trajectory points in the meshing time sequence, the correspondence between the tooth surface evaluation points and the tooth surface contact trajectory points is matched to determine the evaluation points and generate a record of the evaluation points. Based on the torque data, gear geometry records, center distance, and meshing motion relationship records in the current load calculation segment, the total normal load is converted. Combined with the current local contact stiffness in the records of the evaluation points, the total normal load at the same meshing moment is allocated to generate the allocated normal load.

4. The gear contact fatigue life assessment method considering multi-stress coupling as described in claim 1, characterized in that, The step of extracting the tooth surface normal contact stress history and generating an effective fatigue cycle record based on the multi-stress synchronous component record includes: The five types of multi-stress components within the same tooth surface evaluation point and the same load calculation segment are collected from the multi-stress synchronous component records. The stress history record of the current load calculation segment is formed by combining the correspondence between the tooth surface evaluation point and the layer depth evaluation record. Based on the stress history record, the normal contact stress history of the tooth surface is extracted in chronological order of engagement time. The contact cycle is divided by engagement and disengagement time to generate an effective fatigue cycle record.

5. The method for gear contact fatigue life assessment considering multi-stress coupling of claim 1, wherein, The calculation of the cumulative residual stress relaxation, updating the initial residual stress for the next load calculation segment, and generating a residual stress update record include: Based on effective fatigue cycle records, the time intervals of tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress and current residual stress are compared to screen synchronously involved stresses and generate synchronously involved stress records and segmented effective fatigue cycle records. By synchronously participating in stress recording and segmented effective fatigue cycle recording, a local coordinate system of the tooth surface is established. The tooth surface normal contact stress, tooth surface friction shear stress, load fluctuation additional stress, tooth surface thermal stress and current residual stress are mapped into a three-dimensional stress tensor to form a multiaxial stress state. The maximum shear stress amplitude, the average hydrostatic stress and the number of cycles that can be withstood are obtained. Based on the cycle start meshing cycle number, cycle end meshing cycle number and the number of load spectrum repetitions in the load calculation segment record corresponding to the effective fatigue cycle record or segmented effective fatigue cycle record, the actual number of cycles is generated to obtain the effective fatigue cycle damage record. Based on effective fatigue cycle damage records, combined with temperature data and actual number of cycles, the cumulative amount of residual stress relaxation is calculated, the residual stress relaxation calibration data is matched, the initial residual stress of the next load calculation segment is updated, and the residual stress update record is generated.

6. The method for gear contact fatigue life assessment considering multi-stress coupling according to claim 5, characterized in that, The process of generating a cumulative fatigue damage record and comparing the cumulative fatigue damage record with the cumulative damage value at the end of fatigue includes: Collect effective fatigue cycle damage records, accumulate fatigue damage increments according to the tooth surface evaluation points and load calculation segment numbers, and generate cumulative fatigue damage records; Compare the cumulative fatigue damage record with the cumulative fatigue termination damage value. When the cumulative fatigue termination damage value is reached, generate a life termination candidate record. When the cumulative fatigue termination damage value is not reached, register the non-termination status.

7. The gear contact fatigue life assessment method considering multi-stress coupling as described in claim 6, characterized in that, The step of updating the initial local contact stiffness of the next load calculation segment and generating the input record for the next load calculation segment in the non-termination state includes: Based on the cumulative fatigue damage record corresponding to the unterminated state, the cumulative fatigue damage corresponding to the tooth surface evaluation point is collected according to the tooth surface contact trajectory point, and the equivalent cumulative fatigue damage of the tooth surface contact trajectory point is generated. The local contact stiffness calibration data corresponding to the tooth surface contact trajectory point is read and matched. The initial local contact stiffness of the next load calculation segment is updated according to the equivalent cumulative fatigue damage of the tooth surface contact trajectory point. Combined with the residual stress update record, the initial local contact stiffness of the next load calculation segment corresponding to the tooth surface contact trajectory point and the initial residual stress of the next load calculation segment corresponding to the tooth surface evaluation point are bound together to generate the input record of the next load calculation segment.

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