Gas turbine rolling bearing dynamic stress calculation method, device, medium and product

Abstract

The invention discloses a method, device, medium and product for calculating dynamic stress of a gas turbine rolling bearing, and relates to the technical field of stress calculation. The method comprises: calculating the impact acceleration of the gas turbine rolling bearing according to the working condition curve of the impact load working condition of the gas turbine rolling bearing, calculating the actual value of the total load based on the impact acceleration, taking the initial pressure distribution as input, calculating the pressure distribution and shear stress distribution by using the oil film thickness equation, the Reynolds equation and the non-Newtonian fluid model under the constraint of the actual value of the total load, further calculating the stress distribution of the contact surface and sub-surface between the rolling element and the inner ring in the gas turbine rolling bearing according to the pressure distribution and the shear stress distribution, and being able to consider the bearing lubrication condition in the stress calculation process under the impact load working condition, so as to accurately calculate the dynamic stress of the gas turbine rolling bearing under the impact load working condition.

Description

Technical Field

[0001] The invention relates to the technical field of stress calculation, and in particular to a method, device, medium and product for calculating the three-dimensional dynamic stress of a rolling bearing of a gas turbine under an impact load. Background Art

[0002] During the operation of gas turbine rolling bearings, due to the cyclic contact between the rollers and raceways, the bearing rings (including the inner and outer rings) will be affected by cyclic contact stress, resulting in reduced material fatigue performance, which in turn has a significant impact on the accuracy, performance and life of the rolling bearings. The contact state and stress distribution of the bearings are key factors in evaluating the working state and life of the bearings. Most of the existing stress analysis models are oriented to the land and aerospace fields, and are less used in the ship field. The working environment in the ship field is quite different from that in other fields, and its transient and variable typical working conditions need to be considered. However, the existing stress analysis models are either analyzed under dry contact conditions or under steady-state conditions, ignoring the impact of wave impact conditions during actual ship operation.

[0003] Based on this, there is an urgent need for a technology that can accurately calculate the dynamic stress of gas turbine rolling bearings under impact load conditions. Summary of the invention

[0004] The purpose of the present invention is to provide a method, device, medium and product for calculating the dynamic stress of a rolling bearing of a gas turbine, which can accurately calculate the dynamic stress of a rolling bearing of a gas turbine under impact load conditions.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for calculating dynamic stress of a gas turbine rolling bearing, comprising:

[0007] The impact acceleration of the rolling bearing of the gas turbine is calculated according to the working condition curve of the impact load working condition of the rolling bearing of the gas turbine, and the actual value of the total load is calculated based on the impact acceleration; the working condition curve is a curve of the acceleration of the impact load changing with time;

[0008] Taking the initial pressure distribution as input, using the oil film thickness equation and the Reynolds equation to perform iterative calculation to obtain the oil film thickness distribution and the pressure distribution, calculating the total load calculated value according to the pressure distribution, judging whether the total load calculated value is equal to the total load actual value, if not, taking the pressure distribution as the initial pressure distribution, returning to the step of "taking the initial pressure distribution as input, using the oil film thickness equation and the Reynolds equation to perform iterative calculation to obtain the oil film thickness distribution and the pressure distribution"; the oil film thickness distribution includes the oil film thickness at each position point in the calculation area of ​​the gas turbine rolling bearing; the pressure distribution includes the pressure at each position point in the calculation area of ​​the gas turbine rolling bearing; the calculation area includes the contact surface between the rolling element and the inner ring in the gas turbine rolling bearing;

[0009] The oil film thickness distribution and the pressure distribution are used as inputs to calculate the shear stress distribution using a non-Newtonian fluid model; the shear stress distribution includes the shear stress at each position point in the calculation area of ​​the gas turbine rolling bearing;

[0010] The stress distribution of the contact surface and the sub-surface between the rolling element and the inner ring in the rolling bearing of the gas turbine is calculated based on the pressure distribution and the shear stress distribution.

[0011] A computer device comprises: a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-mentioned method for calculating dynamic stress of a rolling bearing of a gas turbine.

[0012] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for calculating dynamic stress of a rolling bearing of a gas turbine.

[0013] A computer program product comprises a computer program, which implements the steps of the above-mentioned method for calculating dynamic stress of rolling bearing of a gas turbine when executed by a processor.

[0014] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0015] The present invention provides a method, device, medium and product for calculating the dynamic stress of a rolling bearing of a gas turbine. The method calculates the impact acceleration of the rolling bearing of the gas turbine according to the working condition curve of the impact load working condition of the rolling bearing of the gas turbine, obtains the actual value of the total load based on the calculation of the impact acceleration, takes the initial pressure distribution as input, calculates the pressure distribution and the shear stress distribution by using the oil film thickness equation, the Reynolds equation and the non-Newtonian fluid model under the constraint of the actual value of the total load, further calculates the stress distribution of the contact surface and the sub-surface between the rolling element and the inner ring in the rolling bearing of the gas turbine according to the pressure distribution and the shear stress distribution, and can consider the bearing lubrication condition in the stress calculation process under the impact load working condition, so that the dynamic stress of the rolling bearing of the gas turbine under the impact load working condition can be accurately calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of a method flow chart of a method for calculating dynamic stress of a rolling bearing of a gas turbine provided in Example 1 of the present invention;

[0018] Figure 2 The schematic diagram of the change trend of the dimensionless impact load distribution and the maximum stress distribution of the inner raceway when the initial load condition is 5000N provided in Example 1 of the present invention; wherein, Figure 2 (a) is the dimensionless impact load distribution; Figure 2 (b) is the maximum stress distribution of the inner raceway;

[0019] Figure 3 The three-dimensional cloud diagram of the stress distribution on the bearing surface and sub-surface under the load impact condition provided in Example 1 of the present invention; wherein, Figure 3 (a) is the three-dimensional cloud diagram of the steady-state load stage of 625 calculation steps; Figure 3 (b) is the three-dimensional cloud diagram of the load detonation stage of 1250 calculation steps; Figure 3 (c) is the three-dimensional cloud diagram of the linear decay stage of 1563 calculation steps; Figure 3 (d) is a three-dimensional cloud diagram of the bubble pulsation peak stage at 3438 calculation steps;

[0020] Figure 4 The three-dimensional cloud diagram of the stress distribution on the bearing surface and sub-surface of the xoz plane under the load impact condition provided in Example 1 of the present invention; wherein, Figure 4(a) is the three-dimensional cloud diagram of the steady-state load stage of 625 calculation steps; Figure 4 (b) is the three-dimensional cloud diagram of the load detonation stage of 1250 calculation steps; Figure 4 (c) is the three-dimensional cloud diagram of the linear decay stage of 1563 calculation steps; Figure 4 (d) is a three-dimensional cloud diagram of the bubble pulsation peak stage at 3438 calculation steps;

[0021] Figure 5 The three-dimensional cloud diagram of the stress distribution on the bearing surface and sub-surface of the yoz plane under the load impact condition provided in Example 1 of the present invention; wherein, Figure 5 (a) is the three-dimensional cloud diagram of the steady-state load stage of 625 calculation steps; Figure 5 (b) is the three-dimensional cloud diagram of the load detonation stage of 1250 calculation steps; Figure 5 (c) is the three-dimensional cloud diagram of the linear decay stage of 1563 calculation steps; Figure 5 (d) is a three-dimensional cloud diagram of the bubble pulsation peak stage at 3438 calculation steps;

[0022] Figure 6 The three-dimensional cloud diagram of the stress distribution on the bearing surface and sub-surface under the load impact condition provided in Example 1 of the present invention; wherein, Figure 6 (a) is the three-dimensional cloud image of 5000N; Figure 6 (b) is the three-dimensional cloud image of 7000N; Figure 6 (c) in the figure is the three-dimensional cloud image of 9000N. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] like Figure 1 As shown, a method for calculating dynamic stress of a rolling bearing of a gas turbine in this embodiment includes:

[0026] S1: Calculate the impact acceleration of the gas turbine rolling bearing according to the working condition curve of the impact load working condition of the gas turbine rolling bearing, and obtain the actual value of the total load based on the impact acceleration calculation; the working condition curve is a curve of the acceleration of the impact load changing with time.

[0027] In this embodiment, an impact load equation is first constructed, and then the impact load equation is solved according to the working conditions to obtain the impact acceleration.

[0028] The actual impact load waveform in engineering is very complex. For the convenience of analysis, and the subsequent bubble pulsation peak stage load also affects the hull, this embodiment refers to the empirical formula in the military ship specification BV043 / 85 and performs approximate processing on it to construct the impact load equation.

[0029] Considering the acceleration condition of the rolling bearing of the gas turbine, the rising stage of the shock wave curve is regarded as a step signal, the first half of the falling stage is approximately linear, and the second half is an exponential decay curve. The empirical formula is:

[0030]

[0031] In formula (1), ü(t) is the impact acceleration at time t, t is the working time of the rolling bearing of the gas turbine; ü0 is the peak acceleration of the rising stage; t1 is the end time of the rising stage; is the acceleration at the end of the first half of the descent phase; t2 is the end time of the first half of the descent phase; t3 is the end time of the second half of the descent phase.

[0032] Considering that the peak load in the first bubble pulsation cycle is 10-20% of the peak load of the shock wave, the peak load in the second bubble pulsation cycle is attenuated to 80-90% of the peak load in the first bubble pulsation cycle. For the convenience of analysis, the waveform of each bubble pulsation cycle is simplified to an ideal half-sine wave, and the expression of its shock load (i.e., shock load equation) is:

[0033]

[0034] In formula (2), ü(t) is the impact acceleration at time t; ü p is the peak acceleration of the impact load; τ1 is the duration of the impact load.

[0035] Formula (2) is also the calculation formula for the impact acceleration used in this embodiment. After obtaining the working condition of the bearing (i.e., the working condition curve) through field research, the acceleration peak value and duration can be determined. Substituting them into formula (2) can calculate the impact acceleration at each moment.

[0036] The actual value of the total load is calculated based on the impact acceleration, specifically including: taking the impact acceleration as input, and using Newton's second law to calculate the actual value of the total load, that is, the actual value of the total load is equal to the product of the weight of the gas turbine rolling bearing and the impact acceleration.

[0037] S2: using the initial pressure distribution as input, performing iterative calculation using the oil film thickness equation and the Reynolds equation to obtain the oil film thickness distribution and the pressure distribution, obtaining the total load calculation value according to the pressure distribution, judging whether the total load calculation value is equal to the total load actual value, if not, using the pressure distribution as the initial pressure distribution, and returning to the step of "using the initial pressure distribution as input, performing iterative calculation using the oil film thickness equation and the Reynolds equation to obtain the oil film thickness distribution and the pressure distribution"; the oil film thickness distribution includes the oil film thickness at each position point in the calculation area of ​​the gas turbine rolling bearing; the pressure distribution includes the pressure at each position point in the calculation area of ​​the gas turbine rolling bearing; the calculation area includes the contact surface between the rolling element and the inner ring in the gas turbine rolling bearing.

[0038] In this embodiment, the calculation method of the initial pressure distribution includes: calculating the initial oil film thickness according to an empirical formula, and the initial oil film thickness at each position point in the calculation area is the same, so as to obtain the initial oil film thickness distribution, and substituting the initial oil film thickness distribution into the Reynolds equation to obtain the initial pressure distribution.

[0039] The empirical formula for calculating the initial oil film thickness is as follows:

[0040] H c =2.69G *0.53 U *0.67 W *-0.067 (1-0.61e -0.73k ); (3)

[0041] In formula (3), H c is the initial oil film thickness; G * is the material parameter; U * is the speed parameter; W * is the load parameter; k is the ellipticity ratio, k=b / a, b is the Hertzian contact half-width in the y direction, and a is the Hertzian contact half-width in the x direction.

[0042] After obtaining the initial pressure distribution, the initial pressure distribution is used as input, and the oil film thickness equation and the Reynolds equation are used to perform iterative calculations to obtain the oil film thickness distribution and the pressure distribution. The total load calculation value is obtained based on the pressure distribution, and it is determined whether the total load calculation value is equal to the total load actual value. If so, the iteration is terminated and S3 is executed. If not, the iteration is continued, and the pressure distribution is used as the initial pressure distribution, and the step of "using the initial pressure distribution as input, and performing iterative calculations using the oil film thickness equation and the Reynolds equation to obtain the oil film thickness distribution and the pressure distribution" is returned.

[0043] The total load calculation value obtained according to the pressure distribution calculation specifically includes: integrating the pressure change in the entire calculation area (which may be an elliptical area) to obtain the total load calculation value as follows:

[0044]

[0045] In formula (4), y out is the exit of the calculation area along the y direction; y in is the entrance of the calculation area along the y direction; x out is the exit of the calculation area along the x direction; in is the entrance of the calculation area along the x direction; p(x, y) is the pressure at the position point (x, y); w load Calculates a value for the total load.

[0046] In this embodiment, the initial pressure distribution is used as input, and the oil film thickness equation and the Reynolds equation are used for iterative calculation to obtain the oil film thickness distribution and the pressure distribution, which specifically include:

[0047] (1) Taking the initial pressure distribution as input, the intermediate oil film thickness distribution is calculated using the oil film thickness equation.

[0048] Taking into account the influence of transient curvature radius and elastic deformation during the operation of the bearing, the oil film thickness equation used in this embodiment is:

[0049]

[0050] In formula (5), h is the oil film thickness at the position point (x, y), x and y are the horizontal and vertical coordinates of the position point (x, y), respectively; h0 is the film thickness at the rigid body center of the gas turbine rolling bearing; R is the equivalent comprehensive curvature radius of the gas turbine rolling bearing; v is the elastic deformation at the position point (x, y); δ1 is the surface roughness of the bearing rolling element at the position point (x, y); δ2 is the surface roughness of the inner raceway of the bearing at the position point (x, y). The position point (x, y) is any position point in the calculation area. h0, R, δ1, and δ2 are all structural parameters of the bearing, which are obtained in advance through field research and are known values.

[0051]

[0052] In formula (6), E' is the comprehensive elastic modulus of the bearing contact pair; Ω is the calculation area; For location point The pressure at , which is determined based on the initial pressure distribution, ξ and Location points The horizontal and vertical coordinates of the location point is any point in the calculation area. E' is the structural parameter of the bearing, which is obtained in advance through field research and is a known value.

[0053] After obtaining the initial pressure distribution, determine the pressure at each position point in the calculation area, substitute it into formula (6) to calculate the elastic deformation at each position point, and further substitute it into formula (5) to calculate the oil film thickness at each position point. The oil film thicknesses at all positions constitute the intermediate oil film thickness distribution.

[0054] (2) The oil film thickness distribution in the middle is used as input and the pressure distribution in the middle is calculated using the Reynolds equation.

[0055] This embodiment uses the Reynolds equation to solve the pressure distribution of the rolling element and the inner raceway elastohydrodynamic lubricating oil film under impact conditions. The constructed Reynolds equation (i.e., the transient Reynolds equation expression) is:

[0056]

[0057] In formula (7), ρ is the density of the lubricating oil at the position point (x, y), x and y are the horizontal and vertical coordinates of the position point (x, y), h is the oil film thickness at the position point (x, y), η is the viscosity of the lubricating oil at the position point (x, y), p is the pressure at the position point (x, y), u is the entrainment speed of the rolling element and the inner raceway, and t is time. u is the working parameter of the bearing, which is obtained through field research and is a known value.

[0058] When the pressure on the lubricating oil film changes, the intermolecular forces and distances between the oil film molecules change, and thus the viscosity and density of the oil film change accordingly. In this embodiment, the viscosity and density of the oil film are regarded as pressure-related parameters, and the specific calculation formula is as follows:

[0059] η=η0e αp ; (8)

[0060] In formula (8), η0 is the viscosity of the lubricating oil at room temperature; α is the viscosity-pressure coefficient. Both η0 and α are bearing lubrication parameters, which are obtained through field research and are known values.

[0061]

[0062] In formula (9), ρ0 is the density of lubricating oil at room temperature. ρ0 is the lubrication parameter of the bearing, which is obtained through field research and is a known value.

[0063] The boundary conditions for solving the Reynolds equation are as follows:

[0064]

[0065] In formula (10), p| xin is the boundary pressure in the x direction of the inlet area; p| xout is the boundary pressure in the x direction of the outlet area; p| yin is the boundary pressure in the y direction of the inlet area; p|yout is the boundary pressure in the outlet area in the y direction.

[0066] In the Reynolds equation, only the pressure is an unknown value. The oil film thickness at each position point is determined according to the oil film thickness distribution in the middle. Substituting it into equation (7), combined with the boundary conditions of equation (10), the pressure at each position point is calculated using the successive encryption method. The pressures at all positions constitute the pressure distribution in the middle. The use of the successive encryption method can improve the calculation efficiency. Of course, this embodiment can also use other methods to solve.

[0067] (3) Determine whether the iteration termination condition is met; if so, use the intermediate oil film thickness distribution as the oil film thickness distribution and the intermediate pressure distribution as the pressure distribution; if not, use the intermediate pressure distribution as the initial pressure distribution of the next iteration, and return to the step of "using the initial pressure distribution as input and using the oil film thickness equation to calculate the intermediate oil film thickness distribution".

[0068] In this embodiment, the iteration termination condition may be that the error of the intermediate pressure distribution obtained by two adjacent iterative calculations is less than or equal to a preset error, at which time the pressure distribution is considered to have converged and the iteration is terminated.

[0069] The error calculation formula is:

[0070]

[0071] In formula (11), err is the error; Ω is the calculation area; is the pressure at the position point (x, y) at the current iteration; is the pressure at the position point (x, y) in the previous iteration.

[0072] The preset error can be 10 -3 At this time, when the oil film pressure iteration error err between two adjacent iterations is less than or equal to 10 -3 When , it is judged to be converged, the iteration ends, and the oil film thickness distribution and pressure distribution are obtained.

[0073] S3: using the oil film thickness distribution and the pressure distribution as inputs, calculating the shear stress distribution using a non-Newtonian fluid model; the shear stress distribution includes the shear stress at each position point in the calculation area of ​​the gas turbine rolling bearing.

[0074] Under the elastohydrodynamic lubrication condition, the bearing friction is mainly caused by fluid shear friction. The friction force in the fluid lubrication area is calculated with the help of the viscoelastic Bair-Winer non-Newtonian fluid rheological model. The non-Newtonian fluid model used in this embodiment is:

[0075]

[0076] In formula (12), is the lubricating oil shear velocity at the position point (x, y), which is calculated based on the oil film thickness distribution; G is the derivative of shear stress at the position point (x, y) with respect to time; ∞ is the limiting shear modulus at the position point (x, y), in Pa; τ L is the limiting shear stress at the position point (x, y), in Pa; η is the viscosity of the lubricating oil at the position point (x, y); τ is the shear stress of the lubricating oil at the position point (x, y).

[0077]

[0078] In formula (13), represents approximately equal to; u1 is the rolling element speed; u2 is the inner raceway speed. u1 and u2 are both working parameters of the bearing, which are obtained through field research and are known values.

[0079] G ∞ and τ L It depends on the rheological properties of the lubricating oil, which is a function of pressure and temperature. The lubricating oil used in this embodiment is a typical mineral oil, so the Dyson empirical formula can be used to estimate G ∞ and τ L ,as follows:

[0080]

[0081] In formula (14), P is pressure, that is, p; T is temperature.

[0082] τ L (P, T) = 0.25G ∞ ; (15)

[0083] Substituting equation (13) into equation (12), we can obtain the nonlinear equation for solving the shear stress at any point in the calculation area, as follows:

[0084]

[0085] The shear stress distribution can be calculated using formula (16).

[0086] S4: Calculate the stress distribution of the contact surface and sub-surface between the rolling element and the inner ring in the rolling bearing of the gas turbine according to the pressure distribution and the shear stress distribution.

[0087] In this embodiment, the stress distribution of the contact surface and sub-surface between the rolling element and the inner ring of the rolling bearing of the gas turbine is calculated based on the pressure distribution and the shear stress distribution, which specifically includes:

[0088] (1) Multiple stress components of each three-dimensional point in a solution region of a gas turbine rolling bearing are calculated based on pressure distribution and shear stress distribution; the solution region includes the contact surface and subsurface between the rolling element and the inner ring of the gas turbine rolling bearing.

[0089] According to KL Johnson theory, when there is a unit normal force p(x, y) and a unit tangential force q x (x, y), q y When (x, y) acts on the surface of a semi-infinite body at the same time, the stress components of each three-dimensional point can be given by the following formula:

[0090]

[0091] In formula (17), σ ab (x, y, z) are the stress components at the three-dimensional point (x, y, z), including σ xx , σ xy , σ xz , σ yy , σ zz , σ yz ; is the unit tangential force q acting on the position point (x',y') x The stress components caused by (x', y') at the three-dimensional point (x, y, z) include is the unit tangential force q acting on the position point (x',y') y The stress components caused by (x', y') at the three-dimensional point (x, y, z) include is the stress component caused by the unit normal force p(x',y') acting on the position point (x',y') at the three-dimensional point (x, y, z), including q x (x',y') and q y (x', y') are the components of shear stress in the x-direction and y-direction respectively.

[0092]

[0093] In formula (18), v1 is the Poisson's ratio of the inner raceway; r 2 =x 2 +y 2 ,

[0094]

[0095]

[0096] T22 (x,y,z)=T 11 (y,x,z); (21)

[0097]

[0098] T 23 (x,y,z)=T 13 (y,x,z); (23)

[0099] In the above formula, subscripts 1, 2, and 3 represent x, y, and z, respectively.

[0100] By using the above formula (18)-formula (23), we can get Then, using the pressure distribution and shear stress distribution as input, multiple stress components of each three-dimensional point in the solution area of ​​the gas turbine rolling bearing can be calculated using formula (17).

[0101] (2) For each three-dimensional point, the first principal stress, the second principal stress and the third principal stress of the three-dimensional point are determined based on multiple stress components; the stress of the three-dimensional point is calculated according to the first principal stress, the second principal stress and the third principal stress of the three-dimensional point; the stress includes the equivalent stress and the maximum shear stress.

[0102] Multiple stress components (i.e., σ xx , σ xy , σ xz , σ yy , σ zz , σ yz ) are sorted in descending order, the first stress component is selected as the first principal stress, the second stress component is selected as the second principal stress, and the third stress component is selected as the third principal stress. On the basis of considering the shear force and pressure between the bearings caused by the impact load, the first principal stress σ1, the second principal stress σ2 and the third principal stress σ3 of each three-dimensional point inside the bearing can be solved.

[0103] Equivalent stress between rolling element and inner raceway σ vm (using VonMises stress) as follows:

[0104]

[0105] Maximum shear stress τ between rolling element and inner raceway max as follows:

[0106]

[0107] (3) Based on the stress of all three-dimensional points, the stress distribution on the contact surface and sub-surface between the rolling element and the inner ring in the gas turbine rolling bearing is determined.

[0108] The subsurface refers to the stress of all three-dimensional points inside the bearing, which constitutes the stress distribution of the contact surface and subsurface.

[0109] This embodiment comprehensively considers the typical load excitation of gas turbine rolling bearings and the influence of underwater impact load environment, divides the surface and sub-surface stress excitation sources into two parts: surface normal compressive stress and surface tangential shear stress, which are obtained through bearing elastohydrodynamic lubrication analysis (i.e., oil film thickness equation, Reynolds equation and non-Newtonian fluid model), and combined with the surface and sub-surface stress analysis model (i.e., the formula in S4), the three-dimensional dynamic stress of the bearing contact surface and sub-surface under impact load conditions is accurately predicted, which can effectively improve the accuracy of the predicted distribution of contact surface and sub-surface stress.

[0110] In order to further reveal the changing rules of the bearing contact surface and sub-surface under impact conditions under mixed lubrication conditions, the stress field distribution of rolling bearings under different load conditions is studied:

[0111] This embodiment mainly compares the influence of impact load on bearing surface and sub-surface stress under four groups of different load conditions. The load conditions are w=5000N, w=7000N, w=9000N, and w=11000N, respectively. The calculation parameters are shown in Table 1. The entrainment speed is 3m / s, and the sliding-rolling ratio is 0.2 (wherein the rolling body speed is 3.3m / s and the inner raceway speed is 2.7m / s).

[0112] Table 1 Parameters used in bearing stress analysis calculation

[0113]

[0114] Figure 2 The diagram shows the change trend of dimensionless impact load distribution and maximum stress distribution of the inner raceway when the initial load condition is 5000N. Figure 2 It can be seen that the maximum stress of the surface and subsurface corresponding to the steady-state load stage is 684MPa. When the calculation step reaches 1250, it is the load impact stage (i.e., the load detonation stage), and the maximum stress corresponding to the inner raceway is 936MPa, which is 36.8% higher than the steady-state load stage. When the calculation step is 1250-1563, it is the linear attenuation stage, in which the maximum stress decreases by 8.5%. When the calculation step is 1563-2813, it is the rapid exponential attenuation stage (i.e., the bubble pulsation peak stage), in which the maximum stress decreases by 21%. The effect of the first bubble pulsation on the bearing stress is relatively weak compared with the load detonation stage, and the maximum stress only increases by 6.4% in this stage.

[0115] Figure 3 The diagram shows the three-dimensional stress distribution on the xoy plane at different load impact stages when the initial load condition is 5000N. Figure 3Where a is the length of the calculation area in the x direction, and b is the length of the calculation area in the y direction. Figure 3 It can be seen that the load impact has a very obvious effect on the bearing surface and sub-surface stress. Figure 3 (a)-(d) show the stress change process from load impact to unloading. In the load detonation stage, the stress peak and the area of ​​the high stress area increase significantly compared to the steady-state load stage. During the unloading process, the stress area decreases and gradually returns to a steady-state form.

[0116] Figure 4 The diagram shows the three-dimensional stress distribution in the xoz plane at different load impact stages when the initial load condition is 5000N. The stress peak generated in the load detonation stage is higher than that in the steady-state load stage, and stress acting on the deeper surface will be generated. Taking the load w=5000N as an example, in the steady-state load stage (625 calculation steps), the maximum stress is generated at z=0.73a. When it reaches the load detonation stage, the maximum stress is generated at z=0.96a. When the load completes the first linear unloading process and is in the linear decay stage (1563 calculation steps), the maximum stress is generated at z=0.83a. The impact load causes the maximum subsurface stress to gradually move to the subsurface.

[0117] Figure 5 The diagram shows the three-dimensional stress distribution in the yoz plane at different load impact stages when the initial load condition is 5000N. The stress variation law of the subsurface in the yoz plane is the same as that in the xoz plane. At the same time, the maximum stress of the bearing along the yoz plane is 11.4% lower than that in the xoz plane, which is consistent with the change trend of the results in the existing literature. The maximum stress on the surface with high curvature decreases. When the bearing is affected by the impact load in the yoz plane, the high stress area increases accordingly.

[0118] Figure 6 The stress distribution of the inner raceway under different initial load conditions during the load detonation stage is shown. Figure 6 It can be seen that for the three groups of different initial load conditions, with the increase of initial load, the peak stress between the bearing contact surfaces increases accordingly, and the actual stress area expands in the x direction. When the load w = 5000N, the width of the high stress area is 0.8a. As the load increases to 7000N and 9000N, the corresponding width increases by 0.6a and 0.83a.

[0119] This embodiment aims at the typical working conditions of gas turbine bearings, establishes a three-dimensional dynamic stress analysis model of the bearing surface and sub-surface under impact load, studies the three-dimensional dynamic stress distribution characteristics of the bearing surface and sub-surface under load impact conditions, and compares the bearing sub-surface stress distribution under multiple groups of different initial load conditions. It is found that the sub-surface stress increases significantly in the load detonation stage, and the area and generation depth of the high stress region increase at the same time.

[0120] Example 2

[0121] A computer device comprises: a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of a method for calculating dynamic stress of a rolling bearing of a gas turbine described in Example 1.

[0122] Example 3

[0123] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for calculating dynamic stress of a gas turbine rolling bearing described in Example 1.

[0124] Example 4

[0125] A computer program product includes a computer program, which, when executed by a processor, implements the steps of a method for calculating dynamic stress of a gas turbine rolling bearing described in Example 1.

[0126] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0127] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for calculating dynamic stress of a rolling bearing of a gas turbine, characterized in that: include: Calculating the impact acceleration of the rolling bearing of the gas turbine according to the working condition curve of the impact load working condition of the rolling bearing of the gas turbine, and obtaining the actual value of the total load based on the impact acceleration calculation; The working condition curve is a curve of the acceleration of the impact load changing with time; Taking the initial pressure distribution as input, performing iterative calculation using the oil film thickness equation and the Reynolds equation to obtain the oil film thickness distribution and the pressure distribution, calculating the total load calculated value according to the pressure distribution, judging whether the total load calculated value is equal to the total load actual value, and if not, taking the pressure distribution as the initial pressure distribution, returning to the step of "taking the initial pressure distribution as input, performing iterative calculation using the oil film thickness equation and the Reynolds equation to obtain the oil film thickness distribution and the pressure distribution"; the oil film thickness distribution includes the oil film thickness at each position point in the calculation area of ​​the gas turbine rolling bearing; the pressure distribution includes the pressure at each position point in the calculation area of ​​the gas turbine rolling bearing; the calculation area includes the contact surface between the rolling element and the inner ring in the gas turbine rolling bearing; The oil film thickness distribution and the pressure distribution are used as inputs to calculate the shear stress distribution using a non-Newtonian fluid model; the shear stress distribution includes the shear stress at each position point in the calculation area of ​​the gas turbine rolling bearing; The stress distribution of the contact surface and the sub-surface between the rolling element and the inner ring in the rolling bearing of the gas turbine is calculated based on the pressure distribution and the shear stress distribution.

2. A method for calculating dynamic stress of a gas turbine rolling bearing according to claim 1, characterized in that: The calculation formula for impact acceleration is: in, is the impact acceleration at time t; is the peak acceleration of the impact load; τ1 is the duration of the impact load; The actual value of the total load is calculated based on the impact acceleration, specifically including: The impact acceleration is used as input and Newton's second law is used to calculate the actual value of the total load.

3. A method for calculating dynamic stress of a gas turbine rolling bearing according to claim 1, characterized in that: Taking the initial pressure distribution as input, the oil film thickness equation and Reynolds equation are used for iterative calculation to obtain the oil film thickness distribution and pressure distribution, including: Taking the initial pressure distribution as input, the intermediate oil film thickness distribution is calculated using the oil film thickness equation; The middle oil film thickness distribution is used as input, and the middle pressure distribution is calculated using the Reynolds equation; Determine whether the iteration termination condition is met; if so, use the intermediate oil film thickness distribution as the oil film thickness distribution and the intermediate pressure distribution as the pressure distribution; if not, use the intermediate pressure distribution as the initial pressure distribution of the next iteration, and return to the step of "using the initial pressure distribution as input and using the oil film thickness equation to calculate the intermediate oil film thickness distribution".

4. A method for calculating dynamic stress of a gas turbine rolling bearing according to claim 1, characterized in that: The oil film thickness equation is: Wherein, h is the oil film thickness at the position point (x, y), x and y are the abscissa and ordinate of the position point (x, y), respectively; h0 is the film thickness at the rigid body center of the gas turbine rolling bearing; R is the equivalent comprehensive curvature radius of the gas turbine rolling bearing; v is the elastic deformation at the position point (x, y); δ1 is the surface roughness of the bearing rolling element at the position point (x, y); δ2 is the surface roughness of the inner raceway of the bearing at the position point (x, y); Where, E' is the comprehensive elastic modulus of the bearing contact pair; Ω is the calculation area; For location point The pressure at Location points The horizontal and vertical coordinates of .

5. A method for calculating dynamic stress of a gas turbine rolling bearing according to claim 1, characterized in that: The Reynolds equation is: Wherein, ρ is the density of the lubricating oil at the position point (x, y), x and y are the horizontal and vertical coordinates of the position point (x, y), respectively; h is the oil film thickness at the position point (x, y); η is the viscosity of the lubricating oil at the position point (x, y); p is the pressure at the position point (x, y); u is the entrainment velocity of the rolling element and the inner raceway; t is the time.

6. A method for calculating dynamic stress of a gas turbine rolling bearing according to claim 1, characterized in that: The non-Newtonian fluid model is: in, is the lubricating oil shear velocity at the position point (x, y), which is calculated based on the oil film thickness distribution; is the derivative of the shear stress at the position point (x, y); G ∞ is the limiting shear modulus at the position point (x, y); τ L is the limiting shear stress at the position point (x, y); η is the viscosity of the lubricating oil at the position point (x, y); τ is the shear stress at the position point (x, y).

7. A method for calculating dynamic stress of a gas turbine rolling bearing according to claim 1, characterized in that: The stress distribution of the contact surface and the sub-surface between the rolling element and the inner ring in the rolling bearing of the gas turbine is calculated according to the pressure distribution and the shear stress distribution, specifically including: Calculate multiple stress components of each three-dimensional point in a solution area of ​​the gas turbine rolling bearing according to the pressure distribution and the shear stress distribution; the solution area includes the contact surface and sub-surface between the rolling element and the inner ring in the gas turbine rolling bearing; For each of the three-dimensional points, a first principal stress, a second principal stress and a third principal stress of the three-dimensional point are determined based on a plurality of stress components; the stress of the three-dimensional point is calculated according to the first principal stress, the second principal stress and the third principal stress of the three-dimensional point; the stress includes an equivalent stress and a maximum shear stress; The stress distribution of the contact surface and sub-surface between the rolling element and the inner ring in the rolling bearing of the gas turbine is determined based on the stress of all the three-dimensional points.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the steps of a method for calculating dynamic stress of a rolling bearing of a gas turbine as described in any one of claims 1-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a method for calculating dynamic stress of a rolling bearing of a gas turbine described in any one of claims 1 to 7 are implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of a method for calculating dynamic stress of a rolling bearing of a gas turbine described in any one of claims 1 to 7 are implemented.

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