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GBZ36517-2018: Rolling bearings -- Methods for calculating the modified reference rating life for universally loaded bearings
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Rolling bearings -- Methods for calculating the modified reference rating life for universally loaded bearings
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Basic data | Standard ID | GB/Z 36517-2018 (GB/Z36517-2018) | | Description (Translated English) | Rolling bearings -- Methods for calculating the modified reference rating life for universally loaded bearings | | Sector / Industry | National Standard | | Classification of Chinese Standard | J11 | | Classification of International Standard | 21.100.20 | | Word Count Estimation | 18,188 | | Date of Issue | 2018-07-13 | | Date of Implementation | 2019-05-01 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | GBZ36517-2018: Rolling bearings -- Methods for calculating the modified reference rating life for universally loaded bearings
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Rolling bearings--Methods for calculating the modified reference rating life for universally loading bearings
ICS 21.100.20
J11
National Standardization Guidance Technical Document of the People's Republic of China
Bearing correction for rolling bearings under general load conditions
Reference rated life calculation method
(ISO /T S16281.2008, IDT)
Published on.2018-07-13
2019-05-01 implementation
State market supervision and administration
China National Standardization Administration issued
Foreword
This guidance technical document was drafted in accordance with the rules given in GB/T 1.1-2009.
This guidance document uses the translation method equivalent to ISO /T S16281.2008 "Rolling bearing bearing repair under general load conditions"
Positive reference to the calculation method of the rated life" and ISO /T S16281.2008/Cor.1.2009.
The following technical documents have also been edited as follows.
--- Incorporate the content of the technical corrigendum ISO /T S16281.2008/Cor.1.2009, which corrects equations (19) and (20).
The documents of our country that have a consistent correspondence with the international documents that are normatively cited in this guidance document are as follows.
---GB/T 6391-2010 Rolling bearings rated dynamic load and rated life (ISO 281.2007, IDT)
---GB/T 7811-2015 Rolling bearing parameter symbol (ISO 15241.2012, IDT)
This guidance technical document was proposed by the China Machinery Industry Federation.
This guidance technical document is under the jurisdiction of the National Rolling Bearing Standardization Technical Committee (SAC/TC98).
This guiding technical document drafting unit. Luoyang Bearing Research Institute Co., Ltd., Shanghai Renben Group Co., Ltd., Shanghai Tianan Bearing has
Limited Company, Cixing Group Co., Ltd., Fujian Yongan Bearing Co., Ltd., Zhongshan Yingke Bearing Manufacturing Co., Ltd.
The main drafters of this guiding technical document. Du Xiaoyu, Guo Changjian, Gu Jinfang, Zhao Kun, Chen Defu, Chen Qingxi, Zhao Rongduo.
Introduction
Since the release of ISO 281 in.1990, more information has been gained on pollution, lubrication, installation internal stress, hardening stress and material fatigue.
Knowledge of the effects of load limits and other factors on bearing life. Therefore, it is now more comprehensive to consider bearing bearing life in life calculations.
the elements of.
ISO 281.2007 provides a way to continuously apply new knowledge in this area when calculating the bearing's corrected rating life. however,
The calculation method given in ISO 281.2007 does not take into account the effect of bearing tilt or skew on life and the bearing clearance during operation.
The impact of life. This guidance document describes an advanced calculation method that takes into account not only these effects, but also
Calculate the impact of pollution and other factors to provide the most accurate support.
Bearing correction for rolling bearings under general load conditions
Reference rated life calculation method
1 Scope
This guidance document gives a recommended method for calculating the reference life rating of a bearing correction that takes into account lubrication, contamination and bearings.
Material fatigue load limit, as well as the influence of tilt or skew, bearing working clearance and internal load distribution of rolling elements. This guidance technical document
The calculation method given covers more influence parameters than ISO 281.
The guidance and limitations given in ISO 281 also apply to this guidance document. This calculation method is applicable to the fatigue life of the bearing
Life. Other failure mechanisms, such as wear or micro-peeling (graying), are beyond the scope of this guidance document.
This guidance document applies to inclined single row radial ball bearings that are subjected to radial and axial loads, taking into account radial play and tilt;
This guidance document also applies to inclined single row roller bearings bearing pure radial loads, taking into account radial clearance, edge stress and inclination
oblique. This guidance document also provides a reference method for analyzing internal load distribution under normal load conditions.
Analysis of internal load distribution and modified reference rating life for multi-row bearings or more complex geometric bearings can be guided by this guide
The formula given in the technical paper was introduced. For these bearings, the load distribution for each column needs to be considered.
The main purpose of this guidance document is for computer programs, which together with ISO 281 cover the information required for life calculations.
For accurate life calculations under the above specified conditions, it is recommended to use this guidance technical document or advanced calculations provided by the bearing manufacturer.
Machine calculation method to determine the reference equivalent dynamic load under different load conditions.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
ISO 281.2007 Rolling bearings rated dynamic load and rated life (Rolingbearings-Dynamicloadratingsand
Ratinglife)
ISO 15241 rolling bearing parameter symbols (Rolingbearings-Symbolsforphysicalquantities)
3 symbol
The symbols given in ISO 15241 and the following symbols apply to this document, as well as the terms and definitions in Chapter 3 of ISO 281.2007.
And other definitions in ISO 281.
A. groove center distance of the ball bearing without play and original contact angle, mm
aISO . life correction factor, system method based on life calculation
A1. reliability life correction factor
Ca. axial basic dynamic load rating, N
Cr. radial basic dynamic load rating, N
Cu. fatigue load limit, N
cL. elastic constant of the rolling element when the wire is in contact, N/mm10/9
cP. elastic constant of the rolling element at point contact, N/mm3/2
cS. elastic constant of roller slice, N/mm8/9
Dpw. ball group or roller group pitch diameter, mm
Dw. ball nominal diameter, mm
Dwe. roller diameter for rated load calculation, mm
E. modulus of elasticity, MPa1)
1) 1 MPa = 1 N/mm 2 .
E(χ). The second type of complete elliptic integral
e. subscript of the outer ring or seat
eC. pollution coefficient
F(ρ). relative curvature difference
Fa. bearing axial load (axial component of bearing actual load), N
Fr. bearing radial load (radial component of bearing actual load), N
f[j,k]. stress correction function considering edge load
i. subscript of inner ring or shaft ring
i. number of rolling body columns
K(χ). The first type of complete elliptic integral
Lnmr. corrected reference rating life, 106r
Lwe. effective roller length for rated load calculation, mm
L10r. basic reference rating life, 106r
Mz. Torque acting on the tilt bearing, N·mm
nS. number of slices
Pref, a. axial reference equivalent dynamic load, N
Pref, r. radial reference equivalent dynamic load, N
P(x). contour function, mm
PHe. contact stress at the contact between the outer ring and the rolling element, MPa
PHi. contact stress at the contact between the inner ring and the rolling element, MPa
PkS. equivalent dynamic load of the kth slice of the bearing, N
Q. rolling element load, N
Qce. rolling element load corresponding to the basic dynamic load rating of the outer ring or race, N
Qci. rolling element load corresponding to the basic dynamic load rating of the inner ring or shaft ring, N
Qee. rolling body equivalent dynamic load on the outer ring or race, N
Qei. the equivalent dynamic load of the rolling element on the inner ring or the shaft ring, N
Qj. load of rolling element j, N
Qce. Basic dynamic load rating of a bearing slice at the contact of the outer ring or race, N
Qci. the basic dynamic load rating of a bearing slice at the inner ring or shaft contact, N
Qee. equivalent dynamic load of a bearing slice at the outer ring or race contact, N
Qei. equivalent dynamic load of a bearing slice at the inner ring or shaft contact, N
Qj,k. the load on the kth slice of the roller j, N
Ri. the distance between the center of curvature of the inner ring channel and the axis of rotation, mm
Rp. the convex radius of the spherical roller, mm
Re. outer ring or seat channel radius, mm
Ri. inner ring or shaft ring channel radius, mm
s. bearing radial working clearance, mm
Xk. the distance between the center of the kth slice and the center of the roller, mm
Z. number of rolling bodies
α. bearing nominal contact angle, (°)
Jj. working contact angle of rolling element j, (°)
00. original contact angle, (°)
γ. auxiliary parameter, γ=Dwcosα/Dpw
δ. total elastic deformation of the rolling element in contact with the inner and outer rings, mm
Δj. elastic deformation of rolling element j, mm
Δj,k. elastic deformation of the kth slice of roller j, mm
Δa. relative axial displacement between the two rings of the bearing, mm
Δr. relative radial displacement between the two rings of the bearing, mm
λ. Consider the reduction factor of stress concentration
ν. correction factor for exponential change
νE. Poisson's ratio
ρ. the curvature of the contact surface, mm-1
∑ρ. curvature and mm-1
Φj. angular position of the rolling element j, (°)
χ. the ratio of the long axis of the contact ellipse to the short half axis
ψ. Total skew angle between inner and outer raceways, (°)
Ψj. the total skew angle between the inner raceway and the outer raceway in the plane of the rolling element j, (°)
4 ball bearing
4.1 General
This chapter describes radial and thrust ball bearings that are subjected to radial and axial loads, taking into account radial clearance and tilt.
Analysis of internal load distribution. For the calculation of different geometrical parameters or under more complex load conditions, this technical text can be
The formula given in the article is introduced.
The internal load distribution of the bearing is only for static equilibrium calculation; it is assumed that dynamic effects such as centripetal force and gyroscopic force are not significant, this assumption
Generally effective for low and medium speeds. At high speeds, the effects of centripetal force and gyroscopic force may become prominent and may significantly change the internal load of the bearing
distributed.
4.2 Bearing internal load distribution
4.2.1 Elastic deformation of point contact
The elastic deformation of the point contact can be calculated by Hertz theory. The elastic deformation δ of a single point contact is.
δ=
4.5
1-νE2
πE
K χ( )
∑ρ
χ2E (χ)
Q2/3 (1)
The ratio of the elliptical long semi-axis to the short semi-axis is the root of equation (2).
Χ2-1
K χ( )
Eχ( ) -1
Êê
úú-Fρ( )=0 (2)
Among them, the first type of complete elliptic integral K (χ).
K χ( )=∫
π/2
1- 1-
Χ2
÷ sinφ( ) 2
Êê
Úú
-1/2
Dφ (3)
The second type of complete elliptic integral E(χ).
Eχ( )=∫
π/2
1- 1-
Χ2
÷ sinφ( ) 2
Êê
Úú
Dφ (4)
Curvature at the inner ring contact and ∑ρi.
∑ρi=
Dw
1-γ-
Dw
2ri
÷ (5)
Curvature at the contact of the outer ring and ∑ρe.
∑ρe=
Dw
1 γ-
Dw
2re
÷ (6)
The relative curvature difference Fi(ρ) at the inner ring contact.
Fiρ( )=
1-γ
Dw
2ri
÷/2
1-γ-
Dw
2ri
÷ (7)
The relative curvature difference Fe(ρ) at the contact of the outer ring.
Feρ( )=
1 γ
Dw
2re
÷/2-
1 γ-
Dw
2re
÷ (8)
The total elastic deformation δ in contact with the inner and outer rings is.
δ=
4.5
1-νE2
πE
K χi( )
∑ρi
χi2Eχi( )
K χe( )
∑ρe
χe2Eχe( )
úQ
2/3 (9)
This derives the load-deformation relationship formula (10).
Q=cPδ3/2 (10)
Wherein, the elastic constant cP is.
cP=1.48
1-νE2 K
Χi( )
∑ρi
χi2Eχi( )
K χe( )
∑ρe
χe2Eχe( )
-3/2
(11)
4.2.2 Static balance
For radial ball bearings with radial working clearance s measured in the diameter direction, original contact angle α0=arccos[1―(s/2A)]
In terms of the total elastic deformation δj of the rolling elements.
Δj= \u003cAcosα0 δrcosφj( ) 2 (Asinα0 δa Risinψcosφj)2 -A\u003e
(12)
If the right side of equation (12) is a negative value, it is set to zero.
Note. The original contact angle α0 is generally different from the nominal contact angle α in ISO 281.
In equation (12), A is the center-of-gravity of the channel radius ri and re, see Figure 1.
A=ri re-Dw (13)
Figure 1 Auxiliary geometry parameters
The distance Ri between the center of curvature of the inner ring channel and the axis of rotation is.
Ri=
Dpw
2 ri-
Dw
÷cosα0 (14)
The contact load can be calculated by the elastic deformation of the rolling elements using equation (10), and these contact loads act on the rolling contact working contact angle αj
Direction.
Jj=arctan
Asinα0 δa Risinψcosφj
Acosα0 δrcosφj
÷ (15)
According to the static balance conditions of the external force and moment acting on the bearing ring and the reaction force of the rolling element, the equations can be obtained, see 4.2.2.1 and
4.2.2.2, which can be solved iteratively.
4.2.2.1 The sum of all forces
Fr-cP∑
j=1
Δj3/2cosαjcosφj=0 (16)
Fa-cP∑
j=1
Δj3/2sinαj=0 (17)
4.2.2.2 sum of all moments
Mz-
Dpw
÷cP∑
j=1
Δj3/2sinαjcosφj=0 (18)
4.3 rated life
4.3.1 Rolling element load corresponding to the basic dynamic load rating
4.3.1.1 General
The rolling element loads Qci and Qce corresponding to the basic dynamic load ratings of the inner and outer rings are derived from ISO /T R1281-1 [1].
4.3.1.2 radial ball bearings
For the inner ring, the Qci of single and multi-row bearings can be calculated using the radial basic dynamic load rating Cr.
Qci=
Cr
0.407Zcosα( )i0.7
1 1.044
1-γ
1 γ
1.72 ri
Re
2re-Dw
2ri-Dw
Êê
Úú
0.41
{ }
10/3æ
(19)
For the outer ring, the Qce of single and multi-row bearings can be calculated using the radial basic dynamic load rating Cr.
Qce=
Cr
0.389Zcosα( )i0.7
1 1.044
1-γ
1 γ
1.72 ri
Re
2re-Dw
2ri-Dw
Êê
Úú
0.41
{ }
-10/3æ
(20)
4.3.1.3 Thrust ball bearing with nominal contact angle α≠90°
For inner rings or shaft rings, Qci can be calculated using the axial basic dynamic load rating Ca.
Qci=
Ca
Zsinα 1
1-γ
1 γ
1.72 ri
Re
2re-Dw
2ri-Dw
Êê
Úú
0.41
{ }
10/3æ
(twenty one)
For the outer ring or race, the Qce can be calculated using the axial basic dynamic load rating Ca.
Qce=
Ca
Zsinα 1
1-γ
1 γ
1.72 ri
Re
2re-Dw
2ri-Dw
Êê
Úú
0.41
{ }
-10/3æ
(twenty two)
4.3.1.4 Thrust ball bearing with nominal contact angle α=90°
For the shaft collar, Qci can be calculated using the axial basic dynamic load rating Ca.
Qci=
Ca
Z 1
Ri
Re
2re-Dw
2ri-Dw
Êê
Úú
0.41
{ }
10/3æ
(twenty three)
For the race, Qce can be calculated using the axial basic dynamic load Ca.
Qce=
Ca
Z 1
Ri
Re
2re-Dw
2ri-Dw
Êê
Úú
0.41
{ }
-10/3æ
(twenty four)
4.3.2 Rolling body equivalent dynamic load
The rolling element equivalent dynamic load Qei of the inner ring or the shaft ring that rotates relative to the bearing load is.
Qei=
Z∑
j=1
Qj3
(25)
The rolling element equivalent dynamic load Qei of the inner ring or the shaft ring which is stationary with respect to the bearing load is.
Qei=
Z∑
j=1
Qj10/3
(26)
The equivalent dynamic load Qee of the rolling element of the outer ring or race relative to the bearing load is.
Qee=
Z∑
j=1
Qj10/3
(27)
The rolling element equivalent dynamic load Qee of the outer ring or race rotating relative to the bearing load is.
Qee=
Z∑
j=1
Qj3
(28)
For a normal load distribution, the difference between the equivalent dynamic load of the rolling element of the rotating inner ring and the stationary inner ring is less than 2%. The difference
The difference is generally negligible, especially when the equivalent dynamic load deviations of the rolling elements on the inner and outer rings can partially compensate each other.
When calculating, it is generally considered that the inner ring is rotating and the outer ring is stationary.
4.3.3 Basic reference rating life
The basic reference rated life L10r can be calculated using the rolling element load and the rolling element equivalent dynamic load corresponding to the basic dynamic load rating.
L10r=
Qci
Qei
-10/3
Qce
Qee
-10/3é
Êê
Úú
-9/10
(29)
4.3.4 Reference equivalent dynamic load
The reference equivalent dynamic load Pref,r of the radial ball bearing is.
Pref, r=
Cr
L10r1/3
(30)
The reference equivalent dynamic load Pref, a of the thrust (axial) ball bearing is.
Pref, a=
Ca
L10r1/3
(31)
4.3.5 Correcting the reference rating life
The corrected reference life of the radial ball bearing Lnmr can be calculated using the life correction factor aISO , aISO can use ISO 281.2007
Equation (31) ~ formula (33) to calculate.
Lnmr=a1aISO
Cr
Pref,r
(32)
For thrust ball bearings, the corrected reference rating life is.
Lnmr=a1aISO
Ca
Pref,a
(33)
Among them, the life correction coefficient aISO can be calculated using the formula (37) to the formula (39) of ISO 281.2007.
5 roller bearings
5.1 General
This chapter describes the internal load distribution of radial roller bearings subjected to radial loads under consideration of radial clearance and tilt.
Analysis. For different geometrical parameters of bearings or analytical calculation methods under more complex load conditions, the formula given in this technical document can be used.
roll out.
The internal load distribution of the bearing is only for static equilibrium calculation; it is assumed that dynamic effects such as centripetal force and gyroscopic force are not significant, this assumption
Generally effective for low and medium speeds. At high speeds, the effects of centripetal force and gyroscopic force may become prominent and may significantly change the internal load of the bearing
distributed.
5.2 Bearing internal load distribution
5.2.1 Elastic deformation of line contact
According to reference [4], the elastic deformation of the line contact rolling body can be described as.
Q=cLδ10/9 (34)
Among them, the elastic constant cL of the steel contact parts is.
cL=35948Lwe8/9 (35)
Figure 2 Total deformation of the roller contact
5.2.2 Slice model
For the case where the raceway is cylindrical, the elastic deformation of the skewed rolling body can be described by a slicing model.
To calculate the elastic deformation, the rollers are divided into nS identical slices, as shown in Figure 3. The number of slices nS should be at least 30.
Calculate the load-deformation formula of the load qj,k on the kth slice of the roller j.
Qj,k=cSδj,k10/9 (36)
Where the elastic constant cS is.
cS=
35948Lwe8/9
nS
(37)
For the radial displacement δr of the inner ring, the elastic deformation δj of the rolling element j is.
Δj=δrcosφj-
(38)
In the plane of the rolling element j, the total skew angle ψj (shown in Figure 4) between the raceways is.
Ψj=arctantanψcosφj( ) (39)
This derives the elastic deformation δj,k of the kth slice of the rolling element j.
Δj,k=< δj-xktanψj> (40)
If the right side of equation (40) is a negative value, it is set to zero.
Note. The assumptions in equation (40) are not completely correct when there is the effect of the rib load and the difference between the inner and outer ring contours.
Further subtract the contour depth from the deformation.
Δj,k=< δj-xktanψj-2P xk( ) > (41)
If the right side of equation (41) is a negative value, it is set to zero.
Figure 3 slice model
Figure 4 Skewed roller bearing
5.2.3 Roller profile
If a purely cylindrical roller is loaded, edge stresses may occur which may greatly exceed the calculated Hertzian pressure. Therefore, usually
Reshape the roller.
For steel rollers and general application conditions, the contour function P(xk) of equations (42) to (44) is introduced.
For rollers of length Lwe ≤ 2.5Dwe.
P xk( )=0.00035Dweln
1- 2xk/Lwe( ) 2
Êê
Úú (42)
For rollers of length Lwe > 2.5 Dwe, the contour function defined by the segmentation should be used.
When xk ≤
Lwe-2.5Dwe
Time.
P xk( )=0 (43)
When xk >
Lwe-2.5Dwe
Time.
P xk( )=0.00050Dweln
1- 2xk - Lwe-2.5Dwe( )[ ]/2.5Dwe{ }2
÷ (44)
The contour functions in equations (42) to (44) give approximations. Actual roller design based on manufacturer's expertise may deviate significantly
These reference geometry parameters.
5.2.4 Static balance
The equations can be obtained according to the static equilibrium conditions of the external force and moment acting on the bearing ring and the reaction force of the rolling element, see 5.2.4.1 and
5.2.4.2, which can be solved by iteration.
5.2.4.1 The sum of all forces
Fr-
cL
nS∑
j=1
Cosφj∑
nS
k=1
Δj,k10/9( )=0 (45)
5.2.4.2 sum of all moments
MZ-
cL
nS∑
j=1
Cosφj∑
nS
k=1
Xkδj,k10/9( )=0 (46)
5.3 rated life
5.3.1 Rolling element load corresponding to the basic dynamic load rating
5.3.1.1 General
The rolling element loads Qci and Qce corresponding to the basic dynamic load ratings of the inner and outer rings are derived from ISO /T R1281-1 [1].
5.3.1.2 Radial roller bearings
For single-row and multi-row bearings, the rolling element loads Qci and Qce corresponding to the basic dynamic load ratings of the inner and outer rings are available in radial basis
The fixed load Cr is calculated.
Qci=
Λν
Cr
0.378Zcosα( )i7/9
1 1.038
1-γ
1 γ
143/108é
Êê
Úú
{ }
(47)
Qce=
Λν
Cr
0.364Zcosα( )i7/9
1 1.038
1-γ
1 γ
143/108é
Êê
Úú
-9/2
{ }
(48)
According to reference [1],
Λν=0.83 (49)
The value of λν needs to be carefully analyzed for contact stress as described in reference [5], [6] or [7], or in the application of equation (60).
The stress concentration approximation formula.
5.3.1.3 Thrust roller bearings with nominal contact angle α≠90°
The rolling element loads Qci and Qce corresponding to the basic dynamic load rating of the inner ring (shaft ring) and the outer ring (seat ring) can be used for the axial basic dynamic load rating.
Load Ca to calculate.
Qci=
Λν
Ca
Zsinα 1
1-γ
1 γ
143/108é
Êê
Úú
{ }
(50)
Qce=
Λν
Ca
Zsinα 1
1-γ
1 γ
143/108é
Êê
Úú
-9/2
{ }
(51)
In the formula.
Λν=0.73 (52)
The value of λν needs to be carefully analyzed for contact stress as described in reference [5], [6] or [7], or in the application of equation (60).
The stress concentration approximation formula.
5.3.1.4 Thrust roller bearing with nominal contact angle α=90°
The rolling element loads Qci and Qce corresponding to the basic dynamic load rating of the collar and the race can be calculated from the axial basic dynamic load Ca.
Qci=
Λν
Ca
Z × 2
2/9 (53)
Qce=
Λν
Ca
Z × 2
2/9 (54)
In the formula.
Λν=0.73 (55)
The value of λν needs to be carefully analyzed for contact stress as described in reference [5], [6] or [7], or in the application of equation (60).
The stress concentration approximation formula.
5.3.2 Basic dynamic load rating of bearing slicing
The basic dynamic load qci of a bearing slice of the inner ring is.
Qci=Qci(
nS
(56)
The basic dynamic load qce of a bearing slice of the outer ring is.
Qce=Qce(
nS
(57)
5.3.3 Edge stress concentration
In the case where the rolling elements are only slightly trimmed or severely deflected, edge stresses may occur, which should be considered in the calculation of the rated life. roll
The contact stress distribution over the length of the moving body can be calculated using references [5], [6] or [7]. Based on the calculated length of the roller
For the contact stress distribution, the stress concentration approximation function fi[j,k] on the inner ring raceway can be obtained from equation (58), and the outer ring raceway is obtained from equation (59).
Fe[j,k].
Fij,k[ ]=
pHij,k
Dwe1-γ( )
Lwe
nS
Êê
Úú/qj,k (58)
Fej,k[ ]=
pHej,k
Dwe1 γ( )
Lwe
nS
Êê
Úú/qj,k (59)
As the first approximation, the stress concentration function f[k] determined by the contact stress calculation can be used for the kth slice.
Fik[ ]=fe k[ ]=1- 0.01ln1.985
2k-nS-1
2nS-2
Êê
Úú (60)
This approximation function is only valid for approximate contours obtained using equations (42), (43), and (44), and is assumed to satisfy medium load and total bearing deflection.
The angle is less than 4'. For general calculations, the methods described in references [5], [6] and [7] are recommended.
5.3.4 Equivalent dynamic load on a slice
Equivalent dynamic load q on the kth slice of the inner ring rotated relative to the load.
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