149 results about "Meshing stiffness" patented technology

The invention discloses a power transmission system internal source excitation load and vibration transmission analysis method and system. The method comprises the steps that firstly, gear dynamic meshing rigidity, spline equivalent bearing rigidity and a flexible shaft model are obtained based on parameters of a gear, a spline and a rotating shaft, and then a power transmission system vibration transmission analysis model is established by combining bearing parameters; the method comprises the following steps: respectively obtaining a vibration acceleration signal of each bearing seat position through experiments and simulation, extracting a signal corresponding to each meshing excitation from each bearing seat measuring point signal through a defined comb filter, and calculating the vibration energy contribution of each meshing excitation; finally, through meshing excitation vibration contribution of multiple measuring points and a load transmission rule among parts obtained through simulation, a transmission rule of endogenous excitation load and vibration in the power transmission system is disclosed, vibration characterization of each measuring point in the power transmission system can be accurately obtained based on the method, a theoretical basis is provided for selection of sensitive measuring points, and the method has a wide application prospect. Therefore, support is provided for digital twin modeling and health management of the power transmission system.

The invention discloses a nonlinear dynamic modeling method of a helical gear transmission system considering wear. The method comprises the following specific steps: step (1), establishing a time-varying meshing stiffness calculation model of a helical gear pair in a healthy state; (2) establishing a time-varying meshing stiffness calculation model of the wear fault helical gear pair; (3) establishing a helical gear tooth surface friction model under the condition of mixed elastohydrodynamic lubrication; (4) establishing a deformation equation of the tapered roller bearing; (5) establishing a helical gear transmission system model considering wear, and solving the nonlinear vibration characteristics of the helical gear transmission system under different wear degree faults of the helical gear; the method has the beneficial effects that the nonlinear dynamic model of the helical gear transmission system considering wear is established, and technical support is provided for related technologies of fault dynamic modeling of the current helical gear transmission system.

The invention discloses a dynamic coupling transmission error solving method for a helical gear combined transmission system. The method comprises the following steps: firstly, acquiring basic parameters of the helical gear combined transmission system and establishing a three-dimensional model of the helical gear combined transmission system; secondly, static transmission errors and time-varying meshing stiffness in the gear meshing process are calculated based on finite element analysis; secondly, establishing a bending-twisting-shaft-swinging 18-degree-of-freedom kinetic model of the helical gear combined transmission system considering time-varying meshing rigidity, installation errors, machining errors, gear backlash and meshing damping; inputting gear parameters and working conditions, including parameters such as input torque, output torque and input rotating speed, and acquiring dynamic response of the helical gear combined transmission system by adopting a four-order variable-step Runge-Kutta method; and finally, obtaining a dynamic coupling transmission error of the helical gear transmission system according to a dynamic solving result.

The invention discloses a gear service life prediction method based on a lubrication-vibration coupling model and a related device, and relates to the technical field of gear service life prediction.The method comprises the steps that firstly, according to gear transmission input data, a three-dimensional mixed lubrication model containing a Reynolds equation coupling solving system is established, and meanwhile system excitation is calculated; then the oil film and the meshing rigidity are connected in parallel to form comprehensive rigidity, a bending-torsion coupling kinetic equation containing torsion and transverse freedom degrees is established, and a lubrication-vibration coupling model is constructed; finally, by means of coupling model output, the lubrication state is evaluated, the vibration characteristic is optimized, and the fatigue and abrasion life is predicted. According to the method, the three-dimensional mixed lubrication model and the system excitation calculation and coupling dynamics model are integrated, the lubrication and vibration coupling effect is considered, the limitation of independent analysis is overcome, the evaluation precision is improved, gear parameter optimization, lubrication scheme making and fault diagnosis can be guided, and the method has engineering application value.

The invention provides a straight gear meshing stiffness calculation method considering machining process factors and wear factors, and relates to the field of gear mechanical analysis. The method comprises the following steps: according to the initial roughness of a gear, constructing a gear rough morphology representation model based on a W-M function of a fractal theory, and obtaining the initial rough morphology of the tooth surface of the straight gear; based on an Archard wear model, constructing a gear tooth surface rough morphology evolution model, and obtaining an evolved tooth surface rough morphology; deducing the relationship between the characterization parameters of the evolved tooth surface rough morphology and the power spectrum density of the gear surface rough morphology; on the basis of an energy method, a fractal theory and an elastohydrodynamic lubrication theory, a straight gear meshing stiffness calculation model considering a lubricating oil film and tooth surface abrasion rough morphology evolution is constructed, the straight gear meshing stiffness under different meshing periods is obtained, and the influence of the tooth surface abrasion rough morphology evolution and the lubricating oil film on the straight gear meshing stiffness is comprehensively considered.

The invention provides a gear peeling time-varying meshing stiffness prediction method and system based on a back propagation neural network, and the method comprises the steps: considering a tooth surface peeling fault based on a gear tooth bearing contact analysis method, and constructing a helical gear pair time-varying meshing stiffness calculation model; a real irregular tooth surface peeling area is fitted by adopting a least square ellipse fitting method to obtain an ellipse appearance representation, any peeling position is completely described through six key geometric parameters, the geometric parameters of the ellipse appearance are systematically traversed and fitted, and diversified peeling appearance samples are generated. Introducing a tooth profile deviation matrix corresponding to the peeling morphology sample into a tooth surface bearing contact analysis model, and constructing a training data set; and constructing a back propagation neural network model of multiple hidden layers, and performing end-to-end training by using the training data set, so that the back propagation neural network model learns a nonlinear mapping relationship from geometric parameters to a time-varying meshing stiffness curve, thereby predicting the time-varying meshing stiffness under any peeling morphology.

The invention provides a gear crack rigidity calculation and system vibration coupling solution method considering slice coupling, which comprises the following steps of: calculating bending rigidity, shearing rigidity and axial compression rigidity of slice gear teeth by adopting a slicing method based on gear tooth number, modulus and gear pair dynamic meshing force to obtain gear tooth rigidity of the slice gear teeth; according to whether the gear has cracks or not, slice coupling rigidities in the healthy state and the crack state of the gear are calculated in combination with the gear tooth rigidities of slice gear teeth; calculating the crack-containing gear time-varying meshing stiffness of a single gear pair by combining the contact stiffness and the matrix stiffness of the gear; based on the outer diameter, the inner diameter and the number of rolling bodies of the ball bearing, the bearing supporting force is calculated by combining the dynamic load borne by the bearing; and according to the time-varying meshing stiffness of the crack-containing gear of the single gear pair and the bearing supporting force, a gear-bearing-coupling system kinetic equation is constructed, and the vibration response of the gear-bearing-coupling system is solved. The method can provide reference for early fault diagnosis of the wind turbine generator gearbox.

The invention relates to the technical field of mechanical dynamics, and discloses a gear dynamics modeling method considering meshing position change influence. A gear meshing stiffness model adopted by the gear dynamics modeling method does not simplify the meshing stiffness between a driving gear and a driven gear into the meshing stiffness which equivalently acts on a node and is fixed in spatial position and only variable in amplitude, but truly considers the change of an instantaneous meshing position between gear teeth of the driving gear; that is to say, the adopted gear meshing rigidity model not only considers the change of the rigidity amplitude in the time dimension, but also considers the change of the rigidity position in the space dimension, and the gear meshing rigidity model is more in line with the actual meshing state of the gear.

The invention discloses an involute spur gear meshing stiffness optimization method for modification based on dynamic transmission errors, which is characterized in that the involute tooth profile is accurately modeled, the meshing stiffness is calculated by adopting a Weber energy method, and the impact generated by single-tooth and double-tooth meshing alternation is reduced through tooth profile modification, so that the transmission errors are reduced, and the involute spur gear meshing stiffness is optimized. The technology is applied to an idle gear system, and the meshing rigidity is iteratively optimized by establishing an idle gear nonlinear kinetic equation and analyzing dynamic transmission errors responded by the system until the requirements for transmission precision and design strength are met.

The invention discloses a face gear dynamics analysis method considering hybrid thermal elastohydrodynamic lubrication and microtexture coupling, which comprises the following steps: step 1, based on a gear dynamics theory, constructing an eight-degree-of-freedom face gear-rotor system dynamics model; 2, establishing a finite element analysis model of the micro-texture face gear transmission pair, solving time-varying meshing stiffness and coupling the time-varying meshing stiffness to a system kinetic equation; 3, coupling a micro-texture item representing the film thickness equation with the film thickness equation of mixed thermal elastohydrodynamic lubrication; 4, coupling the mixing and thermal influence with the elastohydrodynamic lubrication basic equation, and establishing a mixed thermal elastohydrodynamic lubrication model; 5, carrying out iterative solution on the mixed thermal elastohydrodynamic lubrication and micro-texture coupling equation, outputting the tooth surface friction force and the friction coefficient of a solution domain, and inputting the tooth surface friction force and the friction coefficient as parameters into a system kinetic equation; and 6, solving the coupled system kinetic equation by using a Runge-Kutta numerical integration method to obtain the kinetic response of the face gear transmission system.

The invention provides a random rotation speed-oriented gear meshing stiffness calculation method, which belongs to the technical field of gear performance evaluation, and comprises the following steps: describing the actual operation state of a gear system by using a random rotation speed; determining the total potential energy of the gear according to the acting force of the meshing points; solving the total potential energy of the gear to obtain a potential energy calculation function about a meshing rotation angle; determining a meshing stiffness calculation function about the meshing rotation angle by using the potential energy calculation function; solving an average value of a single-tooth meshing area and a double-tooth meshing area of the meshing stiffness calculation function; and the meshing rigidity is simplified into a square wave function through the average value, and the meshing rigidity is changed into a time function from a corner function through the generated random rotating speed. According to the method, the running state of the gear system is described by using the random rotating speed, the influence caused by random fluctuation of the rotating speed is considered, the meshing rigidity of a wind power gear box and the like in the actual working environment can be reflected more truly, and the accuracy and applicability of meshing rigidity calculation are remarkably improved.

The application discloses a gear time-varying meshing stiffness measurement method, which comprises the following steps: S1, a measurement model between current and time-varying meshing stiffness is established based on Hertz contact theory and Ishikawa formula; S2, a closed circuit is formed by connecting a driving gear, a driven gear and a power supply in series, and time-varying current of the circuit is measured; and S3, the time-varying current measured in S2 is substituted into the measurement model to obtain time-varying meshing stiffness of the gear. The application improves the measurement precision and efficiency of the gear time-varying meshing stiffness.

The invention relates to the technical field of gear mechanical calculation, in particular to a spur gear and rolling bearing transmission system analysis method, device and equipment and a medium. The method comprises the steps that spur gear design and working condition parameters are obtained, and the meshing process is analyzed to obtain initial meshing rigidity; constructing a transmission dynamics model, and introducing initial rigidity to solve an initial dynamics response; analyzing a meshing process under bearing deformation based on the response, and obtaining a corrected meshing position; the gear tooth stress and tooth surface lubricating state is analyzed based on the position, and the corrected meshing rigidity and the tooth surface friction coefficient are obtained; introducing parameters and solving to obtain a corrected dynamic response; judging whether an iteration stop condition is met or not, and if not, replacing the initial response with the corrected response to repeat the analysis; according to the method, the meshing position, the rigidity and the friction coefficient are dynamically corrected through an iteration mechanism, the coupling effect of bearing deformation and tooth surface friction is considered, and the analysis precision of a straight gear-rolling bearing transmission system is effectively improved.

The invention discloses a torsional vibration suppression strategy for an electric drive system based on a double-layer model predictive control, and relates to the technical field of electric vehicle motors. The invention establishes a mathematical model of a permanent magnet synchronous motor taking into account the dynamic characteristics of the motor based on a stator voltage equation in a d-q coordinate system; based on the dynamics of a gear system, a 19-degree-of-freedom gear transmission system model is established taking into account nonlinear factors such as time-varying meshing stiffness, meshing error, and tooth side clearance; based on the model of the electric drive system, a torsional vibration suppression strategy based on a double-layer model predictive control is proposed, which suppresses the torsional vibration of an integrated electric drive system by controlling the motor target torque and reducing current harmonics and torque fluctuations, thereby enhancing the stability of the electric drive system and improving the comfort of the whole vehicle.

The invention provides a straight gear system crack fault diagnosis method based on an actual crack propagation curve, and the method specifically comprises the steps: building a gear dynamics analysis model based on the modal condensation of a gear; combining historical data of a gear crack fatigue propagation experiment to obtain a tooth root crack propagation path, and substituting the tooth root crack propagation path into the gear dynamics analysis model to obtain the time-varying meshing stiffness of the gear containing the cracks; simulation acceleration signal data are obtained through a gear dynamics analysis model, and tooth root crack degree identification features are established; and the tooth root crack degree identification features serve as actual signals, and the expansion degree of gear cracks is judged through a variational mode decomposition method. The invention provides a method for improving tooth root crack recognition by considering the condition that a center distance error and a misalignment error exist at the same time. According to the method, index construction is carried out through simulation, noise interference of the measurement environment is reduced through a variational mode decomposition reconstruction method, and crack vibration impact characteristics hidden in periodic signals are extracted.

The invention discloses a spiral bevel gear meshing rigidity and vibration characteristic optimization method and a verification method thereof. The spiral bevel gear meshing rigidity and vibration characteristic optimization method comprises the steps that 1, working condition parameters of a spiral bevel gear are determined; 2, establishing a spiral bevel gear geometric model and calculating geometric parameters of the spiral bevel gear geometric model; 3, analyzing and simulating the thermal-mechanical coupling effect of the spiral bevel gear by using multiple physical fields; 4, calculating the maximum stress and the time-varying meshing stiffness of the spiral bevel gear; 5, analyzing and identifying key design parameters influencing the performance of the spiral bevel gear according to a vibration analysis result; 6, performing sensitivity analysis on each parameter, and optimizing the spiral bevel gear design by applying a multi-objective optimization algorithm; and 7, obtaining an optimized vibration analysis result through a harmonic response analysis method according to the maximum stress and the time-varying meshing stiffness of the optimized spiral bevel gear geometric model. The invention has the advantages that the meshing rigidity is improved, the service life is prolonged, and the high-performance requirements of an automobile transmission system and the aerospace field are met.

The application relates to the technical field of mechanical dynamics, and discloses a gear dynamics modeling method considering the influence of meshing position change. The gear dynamics modeling method realized by the method adopts a gear meshing stiffness model which no longer simplifies the meshing stiffness between a driving wheel and a driven wheel into equivalent meshing stiffness acting on a node with a fixed spatial position and only a change in amplitude, but truly considers the change of the instantaneous meshing position between the driving wheel and the driven wheel, that is, the gear meshing stiffness model considers the change of the stiffness amplitude in the time dimension and the change of the stiffness position in the space dimension, and the gear meshing stiffness model is more in line with the actual meshing state of the gear.

This invention belongs to the field of mechanical dynamics technology, and discloses an improved method, medium, and electronic device for load-bearing contact analysis of spiral bevel gears. Based on the tooth contact analysis method, the geometric parameters of the tooth surfaces of the large and small gears are obtained, a load-bearing contact analysis model of the spiral bevel gear pair is constructed, and the overall compliance matrix, overall contact compliance matrix, and local contact compliance matrix of the tooth surface are calculated. A deformation compatibility iterative equation is established, its ill-conditioned nature is analyzed, and a preprocessing matrix is ​​established to improve the deformation compatibility iterative equation. After improvement, the time-varying meshing stiffness and tooth surface load are solved. Based on the tooth surface load, the principal curvature of the tooth surface of the large and small gears is calculated using the Euler analytical method and the principal direction is determined. The contact stress is then solved using Hertz contact theory. This method improves upon the problems of traditional tooth load-bearing contact analysis methods, which suffer from low accuracy and efficiency due to the ill-conditioned nature of the contact compliance matrix under low load conditions and the reliance on numerical differences for curvature calculation.

The invention discloses a spline meshing characteristic calculation method based on a time-varying meshing position. The spline meshing characteristic calculation method comprises the following steps: establishing a spline meshing state characterization model of a spline; the spline tooth backlash and the pressure angle containing parallel misalignment of the spline are obtained through the spline meshing state characterization model; establishing a spline single-tooth meshing stiffness calculation model through a potential energy method, the spline tooth backlash and the pressure angle; spline tooth meshing deformation coordination conditions are obtained according to the spline single-tooth meshing rigidity calculation model; a spline meshing deformation calculation method of the spline is obtained according to the spline tooth meshing deformation coordination condition; establishing a spline meshing force model containing parallel misalignment according to a spline meshing deformation calculation method; and acquiring spline meshing characteristics of the spline according to the spline meshing force model. According to the method, a spline meshing force model containing parallel misalignment is established; the spline meshing characteristics can be described more accurately, and the design of a high-speed, high-reliability and low-vibration mechanical transmission system is facilitated.

The invention discloses a nonlinear dynamic modeling method and system for a planetary gear transmission system, relates to the technical field of transmission systems, and is used for solving the technical problems that in a planetary gear dynamic modeling mode in the prior art, errors of a meshing area and meshing force are large, and the vibration phenomenon of the planetary transmission system cannot be accurately reflected. The invention discloses a nonlinear dynamic modeling method for a planetary gear transmission system. The nonlinear dynamic modeling method comprises the steps of determining a two-stage straight-tooth planetary gear transmission system; establishing a degree-of-freedom model of the external and internal meshing gear pair according to the transmission system; improving the time-varying meshing stiffness of an internal and external meshing pair of the transmission system by using a degree-of-freedom model; obtaining multi-source excitation of the transmission system containing the time-varying meshing angle and the position angle according to the degree-of-freedom model; establishing a nonlinear function of the relative displacement and the gear backlash of the internal and external meshing pairs along the meshing line direction, and acquiring the meshing force of each meshing pair; and according to the time-varying meshing stiffness, the multi-source excitation and the meshing force, establishing a multi-stage planetary transmission kinetic model.

The application discloses a constant engagement characteristic pair-constructing external engagement cylindrical gear pair, and relates to the technical field of gear transmission, comprising a pair-constructing cylindrical gear I and a pair-constructing cylindrical gear II based on conjugate curves. The normal tooth profile curves of the pair-constructing cylindrical gear I and the pair-constructing cylindrical gear II are continuous combination curves with the same curve shape, facilitating machining with the same cutter; the common normal line at the inflection point or the tangent point of the continuous combination curve passes through the node of the gear pair, and the inflection point or the tangent point position can be adjusted according to actual requirements to adjust the sliding rate of the gear pair; the coincidence degree is designed as an integer, and the engagement stiffness can be kept constant, thereby greatly improving the dynamic engagement performance of the gear pair. In the application, the normal tooth profile of the pair-constructing cylindrical gear I and the pair-constructing cylindrical gear II is the same, the engagement point curvature radius is constant and tends to infinity, the sliding rate is constant, and the engagement stiffness is constant, and the application has the technical characteristics of low manufacturing cost, high bearing capacity, high transmission efficiency, low vibration and noise and the like.

The invention discloses an iterative calculation method for time-varying meshing stiffness of a face gear pair. The iterative calculation method is used for accurately calculating a load distribution coefficient and the time-varying meshing stiffness in the meshing process of the face gear pair. The face gear pair is sliced in the radial direction and the axial direction through a slicing method, the slices are calculated and coupled through a potential energy method, the load distribution coefficient is subjected to iterative correction through the time-varying meshing rigidity obtained through calculation in the iterative calculation process, and therefore accurate solving of the time-varying meshing rigidity of the face gear pair is achieved. According to the method, the calculation efficiency and reliability are improved, theoretical support is provided for face gear pair configuration design optimization, and the international related technical blank is filled.

The invention relates to the technical field of mechanical equipment monitoring, in particular to a rotary machinery gear transmission system kinetic parameter identification method, which comprises the following steps: step 1, based on a gear dynamics theory, considering meshing rigidity and meshing damping of a time-varying gear pair, and establishing a transmission chain torsional vibration kinetic model of rotary machinery; step 2, based on the transmission chain dynamic model established in the step 1, respectively establishing parameter identification objective functions of rotational inertia and meshing rigidity; 3, data of angular displacement, angular acceleration and torque of the transmission chain are continuously collected, and data preprocessing is completed; 4, reconstructing a target function of rotational inertia under the reference of the rotor coordinates, and solving the rotational inertia; step 5, based on the rotational inertia identified in the step 4, solving a meshing stiffness objective function; according to the method, the problem that the stability and the reliability of the gear transmission system cannot be accurately predicted by an existing identification method is solved.

A method for calculating the time-varying meshing stiffness of a cracked gear pair considering friction includes: obtaining gear parameters and crack parameters, establishing a gear meshing model, calculating the meshing angle range, and establishing a first cantilever beam model of a healthy gear without considering friction; establishing a second cantilever beam model of a cracked gear without considering friction; calculating the time-varying friction coefficient based on elastohydrodynamic lubrication theory; establishing a third cantilever beam model of a cracked gear considering friction; and deriving, using the potential energy method, a first calculation method for the time-varying meshing stiffness of a healthy gear pair without considering friction, a second calculation method for the time-varying meshing stiffness of a cracked gear pair without considering friction, and a third calculation method for the time-varying meshing stiffness of a cracked gear pair considering friction, based on the three gear cantilever beam models. This invention provides a more accurate time-varying meshing stiffness calculation for the gear pair using a more precise model. The results obtained using this method can effectively diagnose crack faults in gear transmission systems under actual operating conditions.

This invention discloses a nonlinear dynamic modeling method for crack evolution in a helical gear transmission system for vehicles, which includes the following steps: (1) establishing a calculation formula for meshing stiffness of the helical gear pair under cracked conditions using the slice integration method and the potential energy method; (2) establishing an equivalent circuit model of the motor by combining the principles of circuit theory and magnetic circuit theory with coordinate transformation relationship; (3) building an electromechanical coupling model of the motor-gear system based on the mechanical relationship between the motor and the gear transmission system; (4) establishing a model of the electromechanical coupling helical gear transmission system for vehicles and solving the influence mechanism of crack evolution of helical gears on the dynamic characteristics of the electromechanical coupling helical gear transmission system for vehicles; the beneficial effect is that this invention establishes a nonlinear fault dynamic model of the electromechanical coupling transmission system for new energy vehicles, which is of great significance for the design, optimization and life prediction of the helical gear transmission system for new energy vehicles.

This invention discloses a method for solving the dynamic coupling transmission error of a helical gear combined transmission system. The method first obtains the basic parameters of the helical gear combined transmission system and establishes a three-dimensional model of the system. Second, it calculates the static transmission error and time-varying meshing stiffness during gear meshing based on finite element analysis. Next, it establishes an 18-DOF dynamic model of the helical gear combined transmission system, considering time-varying meshing stiffness, installation and machining errors, tooth flank clearance, and meshing damping. Then, it inputs gear parameters and operating conditions, including input torque, output torque, and input speed, and uses the fourth-order variable-step Runge-Kutta method to obtain the dynamic response of the helical gear combined transmission system. Finally, it obtains the dynamic coupling transmission error of the helical gear transmission system based on the dynamic solution results.

The invention specifically discloses a helical gear pair tooth surface load distribution calculation method and system considering through cracks, and the method comprises the following steps: judging the number J of gear tooth pairs participating in meshing at a corresponding moment t, and dispersing the gear tooth pairs into N equant and independent sheet straight gears in the tooth width direction; the total rigidity of the ith normal tooth piece in the bevel gear pair is calculated; the total rigidity of the ith crack tooth piece in the bevel gear pair is calculated; the comprehensive time-varying meshing rigidity of the bevel gear pair is calculated; the inter-tooth load distribution coefficient and the tooth direction load distribution coefficient in the meshing tooth surface of the bevel gear pair are obtained; and calculating the dynamic meshing force (dynamic load) in the gear transmission process, and obtaining the tooth surface load distribution of the helical gear pair under the through crack. By adopting the technical scheme, the dynamic model of the helical gear pair under the through crack is established to calculate the dynamic load of the helical gear pair, and the tooth space distribution coefficient and the tooth direction distribution coefficient of the helical gear pair are multiplied by the dynamic load to obtain the tooth surface dynamic load distribution of the helical gear pair under the through crack.

The application discloses a kind of digital twin driven armored vehicle double-motor transmission mechanism coupling modeling method and application, consider including nonlinear factors such as time-varying engagement stiffness of gear, transmission error and meshing impact, the motion relationship and force relationship between components are described by applying force element, the dynamic model of coupling transmission mechanism is established;According to the dynamic mathematical equation and vector control theory of permanent magnet synchronous motor, the dynamic mathematical model and vector control model of permanent magnet synchronous motor are established;According to the dynamic model of coupling transmission mechanism and the vector control model of permanent magnet synchronous motor, coupling is carried out through electromagnetic torque, load torque and feedback speed, an electromechanical coupling model is established, the sensitivity of different parameters to response signal difference is analyzed based on the residual value of simulation signal and measured signal, sensitive parameters are screened out, the sensitive parameters of model are optimized based on the forgetting least square algorithm, and the model parameters are corrected based on the optimization result, and the digital twin model is updated.

The present application relates to the field of new energy vehicle electric drive technology, and particularly relates to a method and device for optimizing NVH performance of a gear transmission of an electric drive system, a terminal and a medium, the method comprising: performing tooth tip modification on a gear pair of the electric drive system, and using a tooth bearing contact analysis method to calculate time-varying mesh stiffness of the modified gear pair; taking the time-varying mesh stiffness as an excitation source, substituting it into a dynamic equation of the transmission system, and solving to obtain a dynamic response of the transmission system; taking bearing dynamic load in the dynamic response of the transmission system as a boundary condition, establishing a finite element-boundary element coupling model of the gear box, and simulating and predicting noise radiation of the gear box; evaluating improvement effects of different modification schemes on the NVH performance through the simulation and prediction results, and determining optimal gear modification parameters. The present application realizes forward design of simulation driving, shortens development cycle, reduces cost, and effectively improves system NVH quality.

The invention discloses a gear pair meshing stiffness calculation method considering a thermoelastic coupling effect, which relates to the field of gear transmission, and comprises the following steps: establishing a gear temperature field model and a contact model by utilizing a finite element method, obtaining a gear heat conduction matrix and a structural stiffness matrix, and calculating to obtain gear meshing stiffness and tooth surface load distribution based on an actual tooth surface equation. Calculating tooth surface heat flux density based on tooth surface load distribution, tooth surface friction coefficient and relative sliding speed of each meshing position to obtain a gear thermal load matrix, calculating to obtain an equivalent node load matrix according to a gear heat conduction matrix and the thermal load matrix, and calculating to obtain tooth surface thermal deformation by combining the equivalent node load matrix with a gear structure stiffness matrix. And repeating the steps to obtain the meshing rigidity of the gear pair under the thermoelastic coupling effect. According to the method, the gear contact state iterative solution model based on the potential energy method, the matrix polycondensation method and the slicing thought is established, the requirement for computing equipment is lowered, and the solution efficiency is improved.