ISO 6336-6:2019
(Main)Calculation of load capacity of spur and helical gears — Part 6: Calculation of service life under variable load
Calculation of load capacity of spur and helical gears — Part 6: Calculation of service life under variable load
This document specifies the information and standardized conditions necessary for the calculation of the service life (or safety factors for a required life) of gears subject to variable loading for only pitting and tooth root bending strength. If this scope does not apply, refer ISO 6336-1:2019, Clause 4.
Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale — Partie 6: Calcul de la durée de vie en service sous charge variable
Le présent document spécifie les informations et normalise les conditions de calcul de la durée de vie en service (ou des coefficients de sécurité pour une durée de vie exigée) d'engrenages soumis à des conditions de chargement variables, uniquement vis-à-vis de la tenue en fatigue à l'écaillage et la tenue en fatigue en flexion en pied de dent. Si le domaine d'application ne s'applique pas, se référer à l'ISO 6336‑1:2019, Article 4.
Izračun nosilnosti ravnozobih in poševnozobih zobnikov - 6. del: Izračun dobe trajanja pri spremenljivi obremenitvi
General Information
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Buy Standard
Standards Content (Sample)
SLOVENSKI STANDARD
SIST ISO 6336-6:2020
01-oktober-2020
Izračun nosilnosti ravnozobih in poševnozobih zobnikov - 6. del: Izračun dobe
trajanja pri spremenljivi obremenitvi
Calculation of load capacity of spur and helical gears - Part 6: Calculation of service life
under variable loadCalcul de la capacité de charge des engrenages cylindriques à dentures droite et
hélicoïdale
Ta slovenski standard je istoveten z: ISO 6336-6:2019
ICS:
21.200 Gonila Gears
SIST ISO 6336-6:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST ISO 6336-6:2020
INTERNATIONAL ISO
STANDARD 6336-6
Second edition
2019-11
Calculation of load capacity of spur
and helical gears —
Part 6:
Calculation of service life under
variable load
Calcul de la capacité de charge des engrenages cylindriques à
dentures droite et hélicoïdale —
Partie 6: Calcul de la durée de vie en service sous charge variable
Reference number
ISO 6336-6:2019(E)
ISO 2019
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SIST ISO 6336-6:2020
ISO 6336-6:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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SIST ISO 6336-6:2020
ISO 6336-6:2019(E)
Contents Page
Foreword ........................................................................................................................................................................................................................................iv
Introduction ..................................................................................................................................................................................................................................v
1 Scope ................................................................................................................................................................................................................................. 1
2 Normative references ...................................................................................................................................................................................... 1
3 Terms, definitions, symbols and abbreviated terms ....................................................................................................... 1
3.1 Terms and definitions ....................................................................................................................................................................... 1
3.2 Symbols and abbreviated terms............................................................................................................................................... 1
4 General ............................................................................................................................................................................................................................ 5
4.1 Determination of load and stress spectra ........................................................................................................................ 5
4.2 General calculation of service life ........................................................................................................................................... 7
4.3 Palmgren-Miner rule .......................................................................................................................................................................... 8
5 Calculation of service strength on the basis of single-stage strength according to
ISO 6336 series ....................................................................................................................................................................................................... 9
5.1 Basic principles....................................................................................................................................................................................... 9
5.2 Calculation of stress spectra .....................................................................................................................................................13
5.3 Determination of pitting and bending strength values .....................................................................................14
5.4 Determination of safety factors .............................................................................................................................................14
Annex A (normative) Determination of application factor, K , from given load spectrum
using equivalent torque, T ...................................................................................................................................................................16
Annex B (informative) Equivalent cumulative damage ..................................................................................................................22
Annex C (informative) Example calculation for safety factor from given load spectrum ...........................30
Bibliography .............................................................................................................................................................................................................................37
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Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 2, Gear
capacity calculation.This second edition cancels and replaces the first edition (ISO 6336-6:2006), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 6336-6:2006/Cor.1:2007.
The main changes compared to the previous edition are as follows:— in Annex A, examples have been revised;
— integration of Annex B "Equivalent cumulative damage".
A list of all parts in the ISO 6336 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.iv © ISO 2019 – All rights reserved
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Introduction
ISO 6336 (all parts) consists of International Standards, Technical Specifications (TS) and Technical
Reports (TR) under the general title Calculation of load capacity of spur and helical gears (see Table 1).
— International Standards contain calculation methods that are based on widely accepted practices
and have been validated.— Technical Specifications (TS) contain calculation methods that are still subject to further
development.— Technical Reports (TR) contain data that is informative, such as example calculations.
The procedures specified in parts 1 to 19 of the ISO 6336 series cover fatigue analyses for gear rating.
The procedures described in parts 20 to 29 of the ISO 6336 series are predominantly related to the
tribological behavior of the lubricated flank surface contact. Parts 30 to 39 of the ISO 6336 series
include example calculations. The ISO 6336 series allows the addition of new parts under appropriate
numbers to reflect knowledge gained in the future.Requesting standardized calculations according to the ISO 6336 series without referring to specific
parts requires the use of only those parts that are currently designated as International Standards (see
Table 1 for listing). When requesting further calculations, the relevant part or parts of the ISO 6336
series need to be specified. Use of a Technical Specification as acceptance criteria for a specific design
need to be agreed in advance between the manufacturer and the purchaser.Table 1 — Parts of the ISO 6336 series (STATUS AS OF DATE OF PUBLICATION)
Technical
International Technical
Calculation of load capacity of spur and helical gears Specifica-
Standard Report
tion
Part 1: Basic principles, introduction and general influence factors X
Part 2: Calculation of surface durability (pitting) X
Part 3: Calculation of tooth bending strength X
Part 4: Calculation of tooth flank fracture load capacity X
Part 5: Strength and quality of materials X
Part 6: Calculation of service life under variable load X
Part 20: Calculation of scuffing load capacity (also applicable to bevel
and hypoid gears) — Flash temperature method
(replaces: ISO/TR 13989-1)
Part 21: Calculation of scuffing load capacity (also applicable to bevel
and hypoid gears) — Integral temperature method
(replaces: ISO/TR 13989-2)
Part 22: Calculation of micropitting load capacity
(replaces: ISO/TR 15144-1)
Part 30: Calculation examples for the application of ISO 6336-1, 2, 3, 5 X
Part 31: Calculation examples of micropitting load capacity
X
(replaces: ISO/TR 15144-2)
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SIST ISO 6336-6:2020
INTERNATIONAL STANDARD ISO 6336-6:2019(E)
Calculation of load capacity of spur and helical gears —
Part 6:
Calculation of service life under variable load
1 Scope
This document specifies the information and standardized conditions necessary for the calculation of
the service life (or safety factors for a required life) of gears subject to variable loading for only pitting
and tooth root bending strength.If this scope does not apply, refer ISO 6336-1:2019, Clause 4.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1122-1:1998, Vocabulary of gear terms — Part 1: Definitions related to geometry
ISO 6336-1, Calculation of load capacity of spur and helical gears —Part 1: Basic principles, introduction
and general influence factorsISO 6336-2, Calculation of load capacity of spur and helical gears — Part 2: Calculation of surface durability
(pitting)ISO 6336-3, Calculation of load capacity of spur and helical gears — Part 3: Calculation of tooth bending
strength3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6336-1 and ISO 1122-1:1998
apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp— IEC Electropedia: available at http:// www .electropedia .org/
3.2 Symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in ISO 6336-1,
ISO 1122-1:1998 and Table 2 apply.© ISO 2019 – All rights reserved 1
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Table 2 — Symbols and abbreviated terms used in this document
Abbreviated terms
Term Description
Eh material designation for case-hardened wrought steel
GG material designation for grey cast iron
GGG material designation for nodular cast iron (perlitic, bainitic, ferritic structure)
GTS material designation for black malleable cast iron (perlitic structure)IF material designation for flame or induction hardened wrought special steel
NT material designation for nitrided wrought steel, nitriding steel
NV material designation for through-hardened wrought steel, nitrided, nitrocarburized
St material designation for normalized base steel (σ < 800 N/mm )V material designation for through-hardened wrought special steel, alloy or carbon (σ ≥ 800 N/mm )
SymbolsSymbol Description Unit
a centre distance mm
b face width mm
d diameter (without subscript, reference diameter ) mm
d tip diameter mm
F force or load N
F (nominal) transverse tangential load at reference cylinder per mesh N
K constant, factors concerning tooth load —
K application factor (Annex A shall apply for pitting and tooth root bending) —
K transverse load factor (bending) —
K face load factor (bending) —
K transverse load factor (contact stress) —
K face load factor (contact stress) —
K mesh load factor —
K dynamic factor —
m normal module mm
N number of load cycles —
N number of load cycles to failure for bin i —
N number of load cycles of S-N curve —
N number of load cycles for bending damage —
For external gears a, d, d , z and z are positive; for internal gearing, a, d, d and z have a negative sign, z has a
a 1 2 a 2 1positive sign. All calculated diameters have a negative sign for internal gearing.
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Table 2 (continued)
Symbols
Symbol Description Unit
N number of load cycles for pitting damage —
N number of load cycles for endurance limit —
L ref
n number of load cycles for the equivalent damage fatigue curve (Annex B) —
D,i
number of load cycles for the equivalent damage fatigue curve (reference)
n —
D,REF
(Annex B)
n equivalent number of load cycles (Annex B) —
eq,i
n equivalent number of load cycles (reference) (Annex B) —
eq,3REF
n number of load cycles for bin i —
n number of load cycles for contact stress for bin i —
n number of load cycles for tooth root stress for bin i —
n number of load cycles for nominal stress in bin i (Annex B) —
nom,i
p slope of the S-N curve —
S safety factor —
S safety factor for bending —
S safety factor for pitting —
T torque (pinion torque unless specified otherwise) N·m
T equivalent torque N·m
T torque for bin i N·m
T nominal torque N·m
U sum of individual damage parts —
U individual damage parts for bin i —
u gear ratio (|z / z |) ≥ 1 —
2 1
x profile shift coefficient —
Y factor related to tooth root bending —
Y rim thickness factor —
Y deep tooth factor —
tooth form factor, for the influence on nominal tooth root stress with load applied
Y —at the outer point of single pair tooth contact
Y life factor for tooth root stress for reference test conditions —
relative surface factor, the quotient of the gear tooth root surface factor of interest
Y —R rel T
divided by the tooth root surface factor of the reference test gear, Y = Y /Y
R rel T R RT
stress correction factor, for the conversion of the nominal tooth root stress, deter-
Y mined for application of load at the outer point of single pair tooth contact, to the —
local tooth root stressFor external gears a, d, d , z and z are positive; for internal gearing, a, d, d and z have a negative sign, z has a
a 1 2 a 2 1positive sign. All calculated diameters have a negative sign for internal gearing.
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Table 2 (continued)
Symbols
Symbol Description Unit
stress correction factor, relevant to the dimensions of the standard reference
Y —
test gears
Y helix angle factor (tooth root) —
relative notch sensitivity factor, the quotient of the gear notch sensitivity factor of
Y —δ rel T
interest divided by the standard reference test gear factor, Y = Y /Y
δ rel T δ δT
Z factor related to contact stress —
Z , Z single pair tooth contact factors for the pinion, for the wheel —
B D
2 0,5
Z elasticity factor (N/mm )
Z zone factor —
Z lubricant factor —
Z life factor for contact stress —
Z life factor for contact stress for reference test conditions —
Z roughness factor affecting surface durability —
Z velocity factor —
Z work hardening factor —
Z size factor (pitting) —
Z helix angle factor (pitting) —
Z contact ratio factor (pitting) —
z number of teeth —
z virtual number of teeth of a helical gear —
α pressure angle (without subscript, at reference cylinder) °
β helix angle (without subscript, at reference cylinder) °
σ normal stress N/mm
σ stress value used to describe the equivalent damage fatigue curve (Annex B) N/mm
σ tooth root stress N/mmσ tooth root stress limit N/mm
σ tooth root stress for bin i N/mm
σ permissible bending stress N/mm
σ nominal stress number (bending) N/mm
F lim
σ stress value used to describe the permissible S-N curve N/mm
σ contact stress N/mm
σ pitting stress limit N/mm
σ contact stress for bin i N/mm
For external gears a, d, d , z and z are positive; for internal gearing, a, d, d and z have a negative sign, z has a
a 1 2 a 2 1positive sign. All calculated diameters have a negative sign for internal gearing.
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Table 2 (continued)
Symbols
Symbol Description Unit
σ permissible contact stress N/mm
σ stress value used to describe the S-N curve (Annex B) N/mm
σ reference permissible stress level N/mm
REF
σ stress for bin i N/mm
σ nominal stress for bin i (Annex B) N/mm
nom,i
For external gears a, d, d , z and z are positive; for internal gearing, a, d, d and z have a negative sign, z has a
a 1 2 a 2 1positive sign. All calculated diameters have a negative sign for internal gearing.
4 General4.1 Determination of load and stress spectra
Variable loads resulting from a working process, starting process or from operation at or near a critical
speed will cause varying stresses at the gear teeth of a drive system. The magnitude and frequency of
these loads depend upon the driven machine(s), the driver(s) or motor(s) and the dynamic mass elastic
properties of the system.These variable loads (stresses) may be determined by such procedures as
— experimental measurement of the operating loads at the machine in question,
— estimation of the spectrum, if this is known, for a similar machine with a similar operating mode, and
— calculation, using known external excitation and a mass elastic simulation of the drive system,
preferably followed by experimental testing to validate the calculation.To obtain the load spectra for fatigue damage calculation, the range of the measured (or calculated)
loads is divided into bins or classes. Each bin contains the number of load occurrences recorded in its
load range. A widely-used number of bins is 64. These bins can be of an equal size, but it is usually
better to use larger bin sizes at the lower loads and smaller bin sizes at the upper loads in the range. In
this way, the most damaging loads may be limited to fewer calculated stress cycles and the resulting
design is more accurate regarding the effective load. It is recommended that a zero-load bin be included
so that the total time used to rate the gears matches the design operating life. For consistency, the usual
presentation method is to have the highest torque associated with the lowest numbered bins, such that
the most damaging conditions appear towards the top of any table.The cycle count for the load class corresponding to the load value for the highest loaded tooth is
incremented at every load repetition. Table 3 shows as an example of how the torque classes defined in
Table 4 can be applied to specific torque levels and correlated numbers of cycles.
Table 3 — Torque classes/numbers of cycles — Example: classes 38 and 39 (see Table 4)
Torque class, TNumber of cycles, n
N·m
11 620 ≤ T ≤ 12 619 n = 237
38 38
10 565 ≤ T ≤ 11 619 n = 252
39 39
The torques used to evaluate the tooth loading should include the dynamic effects at different
rotational speeds.This spectrum is only valid for the measured or evaluated time period. If the spectrum is extrapolated
to represent the required lifetime, the possibility that there might be torque peaks not frequent enough
to be evaluated in that measured spectrum shall be considered. These transient peaks can have an
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SIST ISO 6336-6:2020
ISO 6336-6:2019(E)
effect on the gear life. Therefore, the evaluated time period could have to be extended to capture
extreme load peaks.Stress spectra concerning bending and pitting can be obtained from the load (torque).
The tooth root stress may also be measured by means of strain gauges in the fillet. The relevant contact
stress may be calculated from the measurements.Table 4 — Example of torque spectrum (with unequal bin sizes for a reducing number of bins)
(see Annex C)Pinion
Data Time
Torque
N·m
Load cycles
Bin no. minimum maximum s h
1 25 502 25 578 0 0,00 0 0
2 25 424 25 501 0 0,00 0 0
3 25 347 25 423 14 0,37 24 0,006 7
4 25 269 25 346 8 0,21 14 0,003 9
5 25 192 25 268 5 0,13 9 0,002 5
6 25 114 25 191 8 0,21 14 0,003 9
7 25 029 25 113 16 0,42 28 0,007 8
8 24 936 25 028 8 0,21 14 0,003 9
9 24 835 24 935 5 0,13 9 0,002 5
10 24 727 24 834 11 0,29 19 0,005 3
11 24 610 24 726 16 0,42 28 0,007 8
12 24 479 24 609 19 0,50 33 0,009 2
13 24 331 24 478 14 0,37 24 0,006 7
14 24 168 24 330 14 0,37 24 0,006 7
15 23 990 24 168 11 0,29 19 0,005 3
16 23 796 23 989 15 0,39 26 0,007 2
17 23 579 23 796 31 0,81 52 0,014 4
18 23 339 23 579 28 0,73 47 0,013 1
19 23 076 23 338 36 0,94 62 0,017 2
20 22 789 23 075 52 1,36 88 0,024 4
21 22 479 22 788 39 1,02 66 0,018 3
22 22 138 22 478 96 2,51 163 0,045 3
23 21 766 22 137 106 2,77 180 0,050 0
24 21 363 21 765 49 1,28 83 0,023 1
25 20 929 21 362 117 3,05 200 0,055 6
26 20 463 20 928 124 3,24 212 0,058 9
27 19 960 20 463 61 1,59 104 0,028 9
28 19 417 19 959 140 3,65 238 0,066 1
29 18 836 19 416 148 3,86 253 0,070 3
30 18 216 18 835 117 3,05 200 0,055 6
31 17 557 18 215 121 3,16 206 0,057 2
32 16 851 17 556 174 4,46 297 0,082 5
33 16 100 16 851 185 4,83 316 0,087 8
34 15 301 16 099 196 5,11 334 0,092 8
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Table 4 (continued)
Pinion
Data Time
Torque
N·m
Load cycles
Bin no. minimum maximum s h
35 14 456 15 301 207 5,40 352 0,097 8
36 13 565 14 456 161 4,20 274 0,076 1
37 12 620 13 564 168 4,38 286 0,079 4
38 11 620 12 619 237 6,18 404 0,112 2
39 10 565 11 619 252 6,58 429 0,119 2
40 9 457 10 565 263 6,86 449 0,124 7
41 8 294 9 456 275 7,18 468 0,130 0
42 7 070 8 294 178 4,65 303 0,084 2
43 5 783 7 069 103 2,69 176 0,048 9
44 4 434 5 782 7 0,18 12 0,003 3
45 3 024 4 434 0 0,00 0 0
46 1 551 3 023 0 0,00 0 0
47 1 1 550 0 0,00 0 0
48 0 0 0 0,00 6 041 469 1 678,2
Total ≥ 3 832 100,0 6 048 000 1 680
4.2 General calculation of service life
The calculated service life is based on the theory that every load cycle (every revolution) is damaging
to the gear. The amount of damage depends on the stress level and can be considered as zero for lower
stress levels.The calculated bending or pitting fatigue life of a gear is a measure of its ability to accumulate discrete
damage until failure occurs.The fatigue life calculation requires
a) the stress spectrum,
b) material fatigue properties, and
c) a damage accumulation method.
The stress spectrum is discussed in 5.1.
Strength values based on material fatigue properties are chosen from applicable S-N curves. Many
specimens shall be tested by stressing them repeatedly at one stress level until failure occurs. This
gives, after a statistical interpretation for a specific probability, a failure cycle number characteristic of
this stress level. Repeating the procedure at different stress levels leads to an S-N curve.
An example of a cumulative stress spectrum is given in Figure 1. Figure 2 shows a cumulative contact
stress spectrum with an S-N curve for specific material fatigue properties.© ISO 2019 – All rights reserved 7
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Key
X cumulative number of applied cycles, N (log)
Y stress, σ (log)
Load spectrum, Σ n , total cycles.
Figure 1 — Example for a cumulative stress spectrum
Linear, non-linear and relative methods are used. Further information can be found in the literature
(References [4], [9], [10] and [17]).4.3 Palmgren-Miner rule
The Palmgren Miner rule — in addition to other rules or modifications — is a widely-used linear damage
accumulation method. It is assumed that the damaging effect of each stress repetition at a given stress
level is equal, which means the first stress cycle at a given stress level is as damaging as the last.
The Palmgren Miner rule operates on the hypothesis that the portion of useful fatigue life used by
a number of repeated stress cycles at a particular stress is equal to the ratio of the total number of
cycles during the fatigue life at a particular stress level according to the S-N curve established for the
material. For example, if a part is stressed for 3 000 cycles at a stress level which would cause failure in
100 000 cycles, 3 % of the fatigue life would be expended. Repeated stress at another stress level would
consume another similarly calculated portion of the total fatigue life.The used material fatigue characteristics and endurance data should be related to a specific and
required failure probability, e.g. 1 %, 5 % or 10 %.When 100 % of the fatigue life is expended in this manner, the part could be expected to fail. The order
in which each of these individual stress cycles is applied is not considered significant in Palmgren Miner
analysis.Failure could be expected when
=10, (1)
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where
n is the number of load cycles for bin i;
N is the number of load cycles to failure for bin i (taken from the appropriate S-N curve).
If there is an endurance limit (upper, horizontal line beyond the knee in Figure 2), the calculation is only
done for stresses above this endurance limit.If the appropriate S-N curve shows no endurance limit (decreasing line beyond the knee (kink point)
in Figure 3), the calculation shall be done for all stress levels. For each stress level, i, the number of
cycles to failure, N , shall be taken from the corresponding stress level of the S-N curve. Other damage
accumulation (including non-linear) hypotheses in addition to the herein described method and
permissible damage sums other than one may be used upon agreement of the purchaser and the gear
box manufacturer.5 Calculation of service strength on the basis of single-stage strength according
to ISO 6336 series5.1 Basic principles
This method is only valid for recalculation. It describes the application of linear cumulative damage
calculations according to the Palmgren Miner rule (see 4.3) and has been chosen because it is widely
known and easy to apply; the choice does not imply that the method is superior to the others described
in the literature (References [4], [9], [10] and [17]).From the individual torque classes, the torques at the upper limit of each torque class and the associated
numbers of cycles shall be listed (see Table 5 for an example).Table 5 — Torq
...
INTERNATIONAL ISO
STANDARD 6336-6
Second edition
2019-11
Calculation of load capacity of spur
and helical gears —
Part 6:
Calculation of service life under
variable load
Calcul de la capacité de charge des engrenages cylindriques à
dentures droite et hélicoïdale —
Partie 6: Calcul de la durée de vie en service sous charge variable
Reference number
ISO 6336-6:2019(E)
ISO 2019
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ISO 6336-6:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
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ISO 6336-6:2019(E)
Contents Page
Foreword ........................................................................................................................................................................................................................................iv
Introduction ..................................................................................................................................................................................................................................v
1 Scope ................................................................................................................................................................................................................................. 1
2 Normative references ...................................................................................................................................................................................... 1
3 Terms, definitions, symbols and abbreviated terms ....................................................................................................... 1
3.1 Terms and definitions ....................................................................................................................................................................... 1
3.2 Symbols and abbreviated terms............................................................................................................................................... 1
4 General ............................................................................................................................................................................................................................ 5
4.1 Determination of load and stress spectra ........................................................................................................................ 5
4.2 General calculation of service life ........................................................................................................................................... 7
4.3 Palmgren-Miner rule .......................................................................................................................................................................... 8
5 Calculation of service strength on the basis of single-stage strength according to
ISO 6336 series ....................................................................................................................................................................................................... 9
5.1 Basic principles....................................................................................................................................................................................... 9
5.2 Calculation of stress spectra .....................................................................................................................................................13
5.3 Determination of pitting and bending strength values .....................................................................................14
5.4 Determination of safety factors .............................................................................................................................................14
Annex A (normative) Determination of application factor, K , from given load spectrum
using equivalent torque, T ...................................................................................................................................................................16
Annex B (informative) Equivalent cumulative damage ..................................................................................................................22
Annex C (informative) Example calculation for safety factor from given load spectrum ...........................30
Bibliography .............................................................................................................................................................................................................................37
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ISO 6336-6:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 2, Gear
capacity calculation.This second edition cancels and replaces the first edition (ISO 6336-6:2006), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 6336-6:2006/Cor.1:2007.
The main changes compared to the previous edition are as follows:— in Annex A, examples have been revised;
— integration of Annex B "Equivalent cumulative damage".
A list of all parts in the ISO 6336 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 6336-6:2019(E)
Introduction
ISO 6336 (all parts) consists of International Standards, Technical Specifications (TS) and Technical
Reports (TR) under the general title Calculation of load capacity of spur and helical gears (see Table 1).
— International Standards contain calculation methods that are based on widely accepted practices
and have been validated.— Technical Specifications (TS) contain calculation methods that are still subject to further
development.— Technical Reports (TR) contain data that is informative, such as example calculations.
The procedures specified in parts 1 to 19 of the ISO 6336 series cover fatigue analyses for gear rating.
The procedures described in parts 20 to 29 of the ISO 6336 series are predominantly related to the
tribological behavior of the lubricated flank surface contact. Parts 30 to 39 of the ISO 6336 series
include example calculations. The ISO 6336 series allows the addition of new parts under appropriate
numbers to reflect knowledge gained in the future.Requesting standardized calculations according to the ISO 6336 series without referring to specific
parts requires the use of only those parts that are currently designated as International Standards (see
Table 1 for listing). When requesting further calculations, the relevant part or parts of the ISO 6336
series need to be specified. Use of a Technical Specification as acceptance criteria for a specific design
need to be agreed in advance between the manufacturer and the purchaser.Table 1 — Parts of the ISO 6336 series (STATUS AS OF DATE OF PUBLICATION)
Technical
International Technical
Calculation of load capacity of spur and helical gears Specifica-
Standard Report
tion
Part 1: Basic principles, introduction and general influence factors X
Part 2: Calculation of surface durability (pitting) X
Part 3: Calculation of tooth bending strength X
Part 4: Calculation of tooth flank fracture load capacity X
Part 5: Strength and quality of materials X
Part 6: Calculation of service life under variable load X
Part 20: Calculation of scuffing load capacity (also applicable to bevel
and hypoid gears) — Flash temperature method
(replaces: ISO/TR 13989-1)
Part 21: Calculation of scuffing load capacity (also applicable to bevel
and hypoid gears) — Integral temperature method
(replaces: ISO/TR 13989-2)
Part 22: Calculation of micropitting load capacity
(replaces: ISO/TR 15144-1)
Part 30: Calculation examples for the application of ISO 6336-1, 2, 3, 5 X
Part 31: Calculation examples of micropitting load capacity
X
(replaces: ISO/TR 15144-2)
© ISO 2019 – All rights reserved v
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INTERNATIONAL STANDARD ISO 6336-6:2019(E)
Calculation of load capacity of spur and helical gears —
Part 6:
Calculation of service life under variable load
1 Scope
This document specifies the information and standardized conditions necessary for the calculation of
the service life (or safety factors for a required life) of gears subject to variable loading for only pitting
and tooth root bending strength.If this scope does not apply, refer ISO 6336-1:2019, Clause 4.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 1122-1:1998, Vocabulary of gear terms — Part 1: Definitions related to geometry
ISO 6336-1, Calculation of load capacity of spur and helical gears —Part 1: Basic principles, introduction
and general influence factorsISO 6336-2, Calculation of load capacity of spur and helical gears — Part 2: Calculation of surface durability
(pitting)ISO 6336-3, Calculation of load capacity of spur and helical gears — Part 3: Calculation of tooth bending
strength3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6336-1 and ISO 1122-1:1998
apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp— IEC Electropedia: available at http:// www .electropedia .org/
3.2 Symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in ISO 6336-1,
ISO 1122-1:1998 and Table 2 apply.© ISO 2019 – All rights reserved 1
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ISO 6336-6:2019(E)
Table 2 — Symbols and abbreviated terms used in this document
Abbreviated terms
Term Description
Eh material designation for case-hardened wrought steel
GG material designation for grey cast iron
GGG material designation for nodular cast iron (perlitic, bainitic, ferritic structure)
GTS material designation for black malleable cast iron (perlitic structure)IF material designation for flame or induction hardened wrought special steel
NT material designation for nitrided wrought steel, nitriding steel
NV material designation for through-hardened wrought steel, nitrided, nitrocarburized
St material designation for normalized base steel (σ < 800 N/mm )V material designation for through-hardened wrought special steel, alloy or carbon (σ ≥ 800 N/mm )
SymbolsSymbol Description Unit
a centre distance mm
b face width mm
d diameter (without subscript, reference diameter ) mm
d tip diameter mm
F force or load N
F (nominal) transverse tangential load at reference cylinder per mesh N
K constant, factors concerning tooth load —
K application factor (Annex A shall apply for pitting and tooth root bending) —
K transverse load factor (bending) —
K face load factor (bending) —
K transverse load factor (contact stress) —
K face load factor (contact stress) —
K mesh load factor —
K dynamic factor —
m normal module mm
N number of load cycles —
N number of load cycles to failure for bin i —
N number of load cycles of S-N curve —
N number of load cycles for bending damage —
For external gears a, d, d , z and z are positive; for internal gearing, a, d, d and z have a negative sign, z has a
a 1 2 a 2 1positive sign. All calculated diameters have a negative sign for internal gearing.
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ISO 6336-6:2019(E)
Table 2 (continued)
Symbols
Symbol Description Unit
N number of load cycles for pitting damage —
N number of load cycles for endurance limit —
L ref
n number of load cycles for the equivalent damage fatigue curve (Annex B) —
D,i
number of load cycles for the equivalent damage fatigue curve (reference)
n —
D,REF
(Annex B)
n equivalent number of load cycles (Annex B) —
eq,i
n equivalent number of load cycles (reference) (Annex B) —
eq,3REF
n number of load cycles for bin i —
n number of load cycles for contact stress for bin i —
n number of load cycles for tooth root stress for bin i —
n number of load cycles for nominal stress in bin i (Annex B) —
nom,i
p slope of the S-N curve —
S safety factor —
S safety factor for bending —
S safety factor for pitting —
T torque (pinion torque unless specified otherwise) N·m
T equivalent torque N·m
T torque for bin i N·m
T nominal torque N·m
U sum of individual damage parts —
U individual damage parts for bin i —
u gear ratio (|z / z |) ≥ 1 —
2 1
x profile shift coefficient —
Y factor related to tooth root bending —
Y rim thickness factor —
Y deep tooth factor —
tooth form factor, for the influence on nominal tooth root stress with load applied
Y —at the outer point of single pair tooth contact
Y life factor for tooth root stress for reference test conditions —
relative surface factor, the quotient of the gear tooth root surface factor of interest
Y —R rel T
divided by the tooth root surface factor of the reference test gear, Y = Y /Y
R rel T R RT
stress correction factor, for the conversion of the nominal tooth root stress, deter-
Y mined for application of load at the outer point of single pair tooth contact, to the —
local tooth root stressFor external gears a, d, d , z and z are positive; for internal gearing, a, d, d and z have a negative sign, z has a
a 1 2 a 2 1positive sign. All calculated diameters have a negative sign for internal gearing.
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ISO 6336-6:2019(E)
Table 2 (continued)
Symbols
Symbol Description Unit
stress correction factor, relevant to the dimensions of the standard reference
Y —
test gears
Y helix angle factor (tooth root) —
relative notch sensitivity factor, the quotient of the gear notch sensitivity factor of
Y —δ rel T
interest divided by the standard reference test gear factor, Y = Y /Y
δ rel T δ δT
Z factor related to contact stress —
Z , Z single pair tooth contact factors for the pinion, for the wheel —
B D
2 0,5
Z elasticity factor (N/mm )
Z zone factor —
Z lubricant factor —
Z life factor for contact stress —
Z life factor for contact stress for reference test conditions —
Z roughness factor affecting surface durability —
Z velocity factor —
Z work hardening factor —
Z size factor (pitting) —
Z helix angle factor (pitting) —
Z contact ratio factor (pitting) —
z number of teeth —
z virtual number of teeth of a helical gear —
α pressure angle (without subscript, at reference cylinder) °
β helix angle (without subscript, at reference cylinder) °
σ normal stress N/mm
σ stress value used to describe the equivalent damage fatigue curve (Annex B) N/mm
σ tooth root stress N/mmσ tooth root stress limit N/mm
σ tooth root stress for bin i N/mm
σ permissible bending stress N/mm
σ nominal stress number (bending) N/mm
F lim
σ stress value used to describe the permissible S-N curve N/mm
σ contact stress N/mm
σ pitting stress limit N/mm
σ contact stress for bin i N/mm
For external gears a, d, d , z and z are positive; for internal gearing, a, d, d and z have a negative sign, z has a
a 1 2 a 2 1positive sign. All calculated diameters have a negative sign for internal gearing.
4 © ISO 2019 – All rights reserved---------------------- Page: 9 ----------------------
ISO 6336-6:2019(E)
Table 2 (continued)
Symbols
Symbol Description Unit
σ permissible contact stress N/mm
σ stress value used to describe the S-N curve (Annex B) N/mm
σ reference permissible stress level N/mm
REF
σ stress for bin i N/mm
σ nominal stress for bin i (Annex B) N/mm
nom,i
For external gears a, d, d , z and z are positive; for internal gearing, a, d, d and z have a negative sign, z has a
a 1 2 a 2 1positive sign. All calculated diameters have a negative sign for internal gearing.
4 General4.1 Determination of load and stress spectra
Variable loads resulting from a working process, starting process or from operation at or near a critical
speed will cause varying stresses at the gear teeth of a drive system. The magnitude and frequency of
these loads depend upon the driven machine(s), the driver(s) or motor(s) and the dynamic mass elastic
properties of the system.These variable loads (stresses) may be determined by such procedures as
— experimental measurement of the operating loads at the machine in question,
— estimation of the spectrum, if this is known, for a similar machine with a similar operating mode, and
— calculation, using known external excitation and a mass elastic simulation of the drive system,
preferably followed by experimental testing to validate the calculation.To obtain the load spectra for fatigue damage calculation, the range of the measured (or calculated)
loads is divided into bins or classes. Each bin contains the number of load occurrences recorded in its
load range. A widely-used number of bins is 64. These bins can be of an equal size, but it is usually
better to use larger bin sizes at the lower loads and smaller bin sizes at the upper loads in the range. In
this way, the most damaging loads may be limited to fewer calculated stress cycles and the resulting
design is more accurate regarding the effective load. It is recommended that a zero-load bin be included
so that the total time used to rate the gears matches the design operating life. For consistency, the usual
presentation method is to have the highest torque associated with the lowest numbered bins, such that
the most damaging conditions appear towards the top of any table.The cycle count for the load class corresponding to the load value for the highest loaded tooth is
incremented at every load repetition. Table 3 shows as an example of how the torque classes defined in
Table 4 can be applied to specific torque levels and correlated numbers of cycles.
Table 3 — Torque classes/numbers of cycles — Example: classes 38 and 39 (see Table 4)
Torque class, TNumber of cycles, n
N·m
11 620 ≤ T ≤ 12 619 n = 237
38 38
10 565 ≤ T ≤ 11 619 n = 252
39 39
The torques used to evaluate the tooth loading should include the dynamic effects at different
rotational speeds.This spectrum is only valid for the measured or evaluated time period. If the spectrum is extrapolated
to represent the required lifetime, the possibility that there might be torque peaks not frequent enough
to be evaluated in that measured spectrum shall be considered. These transient peaks can have an
© ISO 2019 – All rights reserved 5---------------------- Page: 10 ----------------------
ISO 6336-6:2019(E)
effect on the gear life. Therefore, the evaluated time period could have to be extended to capture
extreme load peaks.Stress spectra concerning bending and pitting can be obtained from the load (torque).
The tooth root stress may also be measured by means of strain gauges in the fillet. The relevant contact
stress may be calculated from the measurements.Table 4 — Example of torque spectrum (with unequal bin sizes for a reducing number of bins)
(see Annex C)Pinion
Data Time
Torque
N·m
Load cycles
Bin no. minimum maximum s h
1 25 502 25 578 0 0,00 0 0
2 25 424 25 501 0 0,00 0 0
3 25 347 25 423 14 0,37 24 0,006 7
4 25 269 25 346 8 0,21 14 0,003 9
5 25 192 25 268 5 0,13 9 0,002 5
6 25 114 25 191 8 0,21 14 0,003 9
7 25 029 25 113 16 0,42 28 0,007 8
8 24 936 25 028 8 0,21 14 0,003 9
9 24 835 24 935 5 0,13 9 0,002 5
10 24 727 24 834 11 0,29 19 0,005 3
11 24 610 24 726 16 0,42 28 0,007 8
12 24 479 24 609 19 0,50 33 0,009 2
13 24 331 24 478 14 0,37 24 0,006 7
14 24 168 24 330 14 0,37 24 0,006 7
15 23 990 24 168 11 0,29 19 0,005 3
16 23 796 23 989 15 0,39 26 0,007 2
17 23 579 23 796 31 0,81 52 0,014 4
18 23 339 23 579 28 0,73 47 0,013 1
19 23 076 23 338 36 0,94 62 0,017 2
20 22 789 23 075 52 1,36 88 0,024 4
21 22 479 22 788 39 1,02 66 0,018 3
22 22 138 22 478 96 2,51 163 0,045 3
23 21 766 22 137 106 2,77 180 0,050 0
24 21 363 21 765 49 1,28 83 0,023 1
25 20 929 21 362 117 3,05 200 0,055 6
26 20 463 20 928 124 3,24 212 0,058 9
27 19 960 20 463 61 1,59 104 0,028 9
28 19 417 19 959 140 3,65 238 0,066 1
29 18 836 19 416 148 3,86 253 0,070 3
30 18 216 18 835 117 3,05 200 0,055 6
31 17 557 18 215 121 3,16 206 0,057 2
32 16 851 17 556 174 4,46 297 0,082 5
33 16 100 16 851 185 4,83 316 0,087 8
34 15 301 16 099 196 5,11 334 0,092 8
6 © ISO 2019 – All rights reserved
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ISO 6336-6:2019(E)
Table 4 (continued)
Pinion
Data Time
Torque
N·m
Load cycles
Bin no. minimum maximum s h
35 14 456 15 301 207 5,40 352 0,097 8
36 13 565 14 456 161 4,20 274 0,076 1
37 12 620 13 564 168 4,38 286 0,079 4
38 11 620 12 619 237 6,18 404 0,112 2
39 10 565 11 619 252 6,58 429 0,119 2
40 9 457 10 565 263 6,86 449 0,124 7
41 8 294 9 456 275 7,18 468 0,130 0
42 7 070 8 294 178 4,65 303 0,084 2
43 5 783 7 069 103 2,69 176 0,048 9
44 4 434 5 782 7 0,18 12 0,003 3
45 3 024 4 434 0 0,00 0 0
46 1 551 3 023 0 0,00 0 0
47 1 1 550 0 0,00 0 0
48 0 0 0 0,00 6 041 469 1 678,2
Total ≥ 3 832 100,0 6 048 000 1 680
4.2 General calculation of service life
The calculated service life is based on the theory that every load cycle (every revolution) is damaging
to the gear. The amount of damage depends on the stress level and can be considered as zero for lower
stress levels.The calculated bending or pitting fatigue life of a gear is a measure of its ability to accumulate discrete
damage until failure occurs.The fatigue life calculation requires
a) the stress spectrum,
b) material fatigue properties, and
c) a damage accumulation method.
The stress spectrum is discussed in 5.1.
Strength values based on material fatigue properties are chosen from applicable S-N curves. Many
specimens shall be tested by stressing them repeatedly at one stress level until failure occurs. This
gives, after a statistical interpretation for a specific probability, a failure cycle number characteristic of
this stress level. Repeating the procedure at different stress levels leads to an S-N curve.
An example of a cumulative stress spectrum is given in Figure 1. Figure 2 shows a cumulative contact
stress spectrum with an S-N curve for specific material fatigue properties.© ISO 2019 – All rights reserved 7
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ISO 6336-6:2019(E)
Key
X cumulative number of applied cycles, N (log)
Y stress, σ (log)
Load spectrum, Σ n , total cycles.
Figure 1 — Example for a cumulative stress spectrum
Linear, non-linear and relative methods are used. Further information can be found in the literature
(References [4], [9], [10] and [17]).4.3 Palmgren-Miner rule
The Palmgren Miner rule — in addition to other rules or modifications — is a widely-used linear damage
accumulation method. It is assumed that the damaging effect of each stress repetition at a given stress
level is equal, which means the first stress cycle at a given stress level is as damaging as the last.
The Palmgren Miner rule operates on the hypothesis that the portion of useful fatigue life used by
a number of repeated stress cycles at a particular stress is equal to the ratio of the total number of
cycles during the fatigue life at a particular stress level according to the S-N curve established for the
material. For example, if a part is stressed for 3 000 cycles at a stress level which would cause failure in
100 000 cycles, 3 % of the fatigue life would be expended. Repeated stress at another stress level would
consume another similarly calculated portion of the total fatigue life.The used material fatigue characteristics and endurance data should be related to a specific and
required failure probability, e.g. 1 %, 5 % or 10 %.When 100 % of the fatigue life is expended in this manner, the part could be expected to fail. The order
in which each of these individual stress cycles is applied is not considered significant in Palmgren Miner
analysis.Failure could be expected when
=10, (1)
8 © ISO 2019 – All rights reserved
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ISO 6336-6:2019(E)
where
n is the number of load cycles for bin i;
N is the number of load cycles to failure for bin i (taken from the appropriate S-N curve).
If there is an endurance limit (upper, horizontal line beyond the knee in Figure 2), the calculation is only
done for stresses above this endurance limit.If the appropriate S-N curve shows no endurance limit (decreasing line beyond the knee (kink point)
in Figure 3), the calculation shall be done for all stress levels. For each stress level, i, the number of
cycles to failure, N , shall be taken from the corresponding stress level of the S-N curve. Other damage
accumulation (including non-linear) hypotheses in addition to the herein described method and
permissible damage sums other than one may be used upon agreement of the purchaser and the gear
box manufacturer.5 Calculation of service strength on the basis of single-stage strength according
to ISO 6336 series5.1 Basic principles
This method is only valid for recalculation. It describes the application of linear cumulative damage
calculations according to the Palmgren Miner rule (see 4.3) and has been chosen because it is widely
known and easy to apply; the choice does not imply that the method is superior to the others described
in the literature (References [4], [9], [10] and [17]).From the individual torque classes, the torques at the upper limit of each torque class and the associated
numbers of cycles shall be listed (see Table 5 for an example).Table 5 — Torque classes/numbers of cycles — Example: classes 38 and 39
Upper limit of torque class , T
Number of cycles, n
N⋅m
T < 12 620 N = 237
38 38
T < 11 620 N = 252
39 39
For conservative calculation, sufficiently accurate for a high number of torque classes.
Based on the load spectrum (T , n ), the effective stress levels σ are determined by help of the methods
i i idescribed in ISO 6336-2 and ISO 6336-3 for the pinion or the wheel to obtain a stress spectrum (σ , n )
i ias shown in Figure 2.
© ISO 2019 – All rights reserved 9
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ISO 6336-6:2019(E)
Key
X number of load cycles, N (log)
Y stress, σ (log) or torque, T (log)
Figure 2 — Load and stress spectrum
The stress spectrum (σ , n) combined with the S-N curve σ (N), allows the determination of the
i i Gallowable number of cycles N for each stress level σ (see Figure 3).
i i
Key
X number of load cycles, N (log)
Y stress, σ (log)
σ (N) stress value used to describe the permissible S-N curve
NOTE For each level of stress σ with a number of cycles n the allowable number of cycl
...NORME ISO
INTERNATIONALE 6336-6
Deuxième édition
2019-11
Calcul de la capacité de charge des
engrenages cylindriques à dentures
droite et hélicoïdale —
Partie 6:
Calcul de la durée de vie en service
sous charge variable
Calculation of load capacity of spur and helical gears —
Part 6: Calculation of service life under variable load
Numéro de référence
ISO 6336-6:2019(F)
ISO 2019
---------------------- Page: 1 ----------------------
ISO 6336-6:2019(F)
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ii © ISO 2019 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 6336-6:2019(F)
Sommaire Page
Avant-propos ..............................................................................................................................................................................................................................iv
Introduction ..................................................................................................................................................................................................................................v
1 Domaine d'application ................................................................................................................................................................................... 1
2 Références normatives ................................................................................................................................................................................... 1
3 Termes, définitions, symboles et termes abrégés .............................................................................................................. 1
3.1 Termes et définitions ......................................................................................................................................................................... 1
3.2 Symboles et termes abrégés ........................................................................................................................................................ 1
4 Généralités .................................................................................................................................................................................................................. 5
4.1 Détermination des spectres de charge et de contrainte...................................................................................... 5
4.2 Calcul général de la durée en service................................................................................................................................... 8
4.3 Règle de Palmgren-Miner .............................................................................................................................................................. 9
5 Calcul de la tenue en service sur la base d’un simple étage de réductionconformément à la série ISO 6336 ..................................................................................................................................................10
5.1 Principes de base ...............................................................................................................................................................................10
5.2 Calcul des spectres de contrainte.........................................................................................................................................14
5.3 Détermination des valeurs de la tenue à l’écaillage et à la flexion ..........................................................15
5.4 Détermination des facteurs de sécurité .........................................................................................................................15
Annexe A (normative) Détermination du facteur d’application, K , à partir d’un spectre de
charge utilisant la couple équivalent, T ................................................................................................................................17
Annexe B (informative) Endommagement cumulés équivalents .........................................................................................23
Annexe C (informative) Exemple de calcul de coefficient de sécurité à partir d’un spectre
de charge donné .................................................................................................................................................................................................32
Bibliographie ...........................................................................................................................................................................................................................39
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ISO 6336-6:2019(F)
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes
nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est
en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.
L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d'approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www
.iso .org/ directives).L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de
droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l'élaboration du document sont indiqués dans l'Introduction et/ou dans la liste des déclarations de
brevets reçues par l'ISO (voir www .iso .org/ brevets).Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un
engagement.Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion
de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC), voir le lien suivant: www .iso .org/ iso/ fr/ avant -propos .html.
Le présent document a été élaboré par le comité technique ISO/TC 60, Engrenages, sous-comité SC 2,
Calcul de la capacité des engrenages.Cette deuxième édition annule et remplace la première édition (ISO 6336-6:2006), qui a fait l’objet d’une
révision technique. Le rectificatif technique ISO 6336-6:2006/Cor.1:2007 est incorporé.
Les principales modifications par rapport à l’édition précédente sont les suivantes:
— révision des exemples de l'Annexe A;— intégration de l'Annexe B «Détérioration cumulée équivalente».
Une liste de toutes les parties de la série ISO 6336 se trouve sur le site Web de l’ISO.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes
se trouve à l’adresse www .iso .org/ fr/ members .html.iv © ISO 2019 – Tous droits réservés
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ISO 6336-6:2019(F)
Introduction
L’ISO 6336 (toutes les parties) est constituée de Normes internationales, de Spécifications techniques
(TS) et de Rapports techniques (TR) regroupés sous le titre général Calcul de la capacité de charge des
engrenages cylindriques à dentures droite et hélicoïdale (voir Tableau 1).— Les Normes internationales contiennent des méthodes de calcul qui sont basées sur des pratiques
largement acceptées et qui ont été validées.— Les Spécifications techniques (TS) contiennent des méthodes de calcul qui sont toujours en cours de
développement.— Les Rapports techniques (TR) contiennent des données informatives, telles que des exemples de
calculs.Les modes opératoires spécifiés dans les parties 1 à 19 de la série ISO 6336 traitent des analyses de
la fatigue pour l’évaluation de la tenue en fatigue des engrenages. Les modes opératoires décrits dans
les parties 20 à 29 de la série ISO 6336 sont principalement associés au comportement tribologique
du contact de surface des flancs de denture lubrifiée. Les parties 30 à 39 de la série ISO 6336 incluent
des exemples de calcul. La série ISO 6336 permet d’ajouter de nouvelles parties sous des numéros
appropriés, afin d’intégrer les connaissances acquises ultérieurement.Toute demande de calculs selon la série ISO 6336 sans référence à des parties spécifiques nécessite
d'utiliser uniquement les parties désignées comme Normes internationales (voir la liste du Tableau 1).
Si des calculs supplémentaires sont requis, la ou les partie(s) pertinente(s) de la série ISO 6336 doivent
être spécifiées. L’utilisation d’une Spécification technique en tant que critère d’acceptation pour une
conception spécifique est soumise à un accord commercial.© ISO 2019 – Tous droits réservés v
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ISO 6336-6:2019(F)
Tableau 1 — Parties de la série ISO 6336 (STATUT À LA DATE DE PUBLICATION)
Calcul de la capacité de charge des engrenages Norme Spécification Rapport
cylindriques à dentures droite et hélicoïdale internationale technique technique
Partie 1: Principes de base, introduction et facteurs généraux
d’influence
Partie 2: Calcul de la résistance à la tenue en fatigue à la pression
de contact (écaillage)
Partie 3: Calcul de la tenue en fatigue à la flexion en pied de dent X
Partie 4: Calcul de la capacité de charge en rupture de flanc des dents X
Partie 5: Résistance et qualité des matériaux X
Partie 6: Calcul de la durée de vie en service sous charge variable X
Partie 20: Calcul de la capacité de charge au grippage (applicable
également aux engrenages coniques et hypoïdes) — Méthode de
la température éclair
(remplace: ISO/TR 13989-1)
Partie 21: Calcul de la capacité de charge au grippage (applicable
également aux engrenages coniques et hypoïdes) — Méthode de
la température intégrale
(Remplace: ISO/TR 13989-2)
Partie 22: Calcul de la capacité de charge aux micropiqûres
(remplace: ISO/TR 15144-1)
Partie 30: Exemples d’application de l’ISO 6336 Parties 1, 2, 3, 5 X
Partie 31: Exemples de calcul de la capacité de charge aux
micropiqûres
(Remplace: ISO/TR 15144-2)
vi © ISO 2019 – Tous droits réservés
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NORME INTERNATIONALE ISO 6336-6:2019(F)
Calcul de la capacité de charge des engrenages
cylindriques à dentures droite et hélicoïdale —
Partie 6:
Calcul de la durée de vie en service sous charge variable
1 Domaine d'application
Le présent document spécifie les informations et normalise les conditions de calcul de la durée de vie
en service (ou des coefficients de sécurité pour une durée de vie exigée) d’engrenages soumis à des
conditions de chargement variables, uniquement vis-à-vis de la tenue en fatigue à l’écaillage et la tenue
en fatigue en flexion en pied de dent.Si le domaine d’application ne s’applique pas, se référer à l’ISO 6336-1:2019, Article 4.
2 Références normativesLes documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.
Pour les références non datées, la dernière édition du document de référence s'applique (y compris les
éventuels amendements).ISO 1122-1:1998, Vocabulaire des engrenages — Partie 1: Définitions géométriques
ISO 6336-1, Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale —
Partie 1: Principes de base, introduction et facteurs généraux d’influenceISO 6336-2, Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale —
Partie 2: Calcul de la tenue en fatigue à la pression de contact (écaillage)ISO 6336-3, Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale —
Partie 3: Calcul de la tenue en fatigue à la flexion en pied de dent3 Termes, définitions, symboles et termes abrégés
3.1 Termes et définitions
Pour les besoins du présent document, les termes et les définitions donnés dans l’ISO 6336-1 et
l’ISO 1122-1:1998 s’appliquent.L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:— ISO Online browsing platform: disponible à l’adresse http:// www .iso .org/ obp
— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/3.2 Symboles et termes abrégés
Pour les besoins du présent document, les symboles et termes abrégés donnés dans les ISO 6336-1,
ISO 1122-1:1998 et au Tableau 2 s’appliquent.© ISO 2019 – Tous droits réservés 1
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ISO 6336-6:2019(F)
Tableau 2 — Symboles et termes abrégés utilisés dans le présent document
Abréviations
Terme Description
Eh appellation matière pour les aciers forgés, cémentés trempés et revenus
GG appellation matière pour les fontes grises
GGG appellation matière pour les fontes ductiles (structure perlitique, bainitique, ferritique)
GTS appellation matière pour les fontes malléables (structure perlitique)IF appellation matière pour les aciers forgés, durcis superficiellement par trempe après chauffage
à la flamme ou par inductionNT appellation matière pour les aciers forgés de nitruration, nitrurés
NV appellation matière pour les aciers forgés trempés à cœur de nitruration, nitrocarburés
St appellation matière pour les aciers de base normalisés (σ < 800 N/mm )V appellation matière pour les aciers, alliages ou carbone forgés trempés et revenus (σ ≥ 800 N/mm )
SymbolesSymbole Description Unité
a entraxe mm
b largeur de denture mm
d diamètre (sans indice, diamètre de référence ) mm
d diamètre de tête mm
F force ou charge N
F force tangentielle (nominale) sur le cylindre de référence par engrènement N
K constante, facteurs concernant la charge sur les dents —
K facteur d’application (l'Annexe A doit s'appliquer pour la tenue à l’écaillage et —
à la flexion en pied de dent)K facteur de distribution transversale de la charge (flexion) —
K facteur de distribution longitudinale de la charge (flexion) —
K facteur de distribution transversale de la charge (pression de contact) —
K facteur de distribution longitudinale de la charge (pression de contact) —
K facteur de la charge sur l’engrènement —
K facteur dynamique —
m module normal mm
N nombre de cycles de mise en charge —
N nombre de cycles de mise à la défaillance pour la catégorie i —
N nombre de cycles de mise en charge de la courbe S-N —
N nombre de cycles de mise en charge pour la détérioration par flexion —
N nombre de cycles de mise en charge pour la détérioration par écaillage —
N nombre de cycles de mise en charge pour la limite d'endurance —
L ref
n nombre de cycles de mise en charge pour la courbe d’endommagement équivalent —
D,i
en fatigue (Annexe B)
n nombre de cycles de mise en charge pour la courbe d’endommagement équivalent —
D,REF
en fatigue (référence) (Annexe B)
n nombre équivalent de cycles de mise en charge (Annexe B) —
eq,i
n nombre équivalent de cycles de mise en charge (référence) (Annexe B) —
eq,3REF
Pour les engrenages à denture extérieure a, d, d , z et z sont positifs; pour les engrenages à denture intérieure, a, d,
a 1 2d et z ont un signe négatif, z a un signe positif. Tous les diamètres calculés ont un signe négatif pour les roues dentées à
a 2 1denture intérieure.
2 © ISO 2019 – Tous droits réservés
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ISO 6336-6:2019(F)
Tableau 2 (suite)
Symboles
Symbole Description Unité
n nombre de cycles de mise en charge pour la catégorie i —
n nombre de cycles de mise en charge pour la pression de contact pour la catégorie i —
nombre de cycles de mise en charge pour la contrainte en pied de dent pour la —catégrie i
n nombre de cycles de mise en charge pour la contrainte nominale dans la catégorie i —
nom,i(Annexe B)
p pente de la courbe d’endommagement de la courbe S-N —
S coefficient de sécurité —
S coefficient de sécurité vis-à-vis de la flexion en pied de dent —
S coefficient de sécurité vis-à-vis de la formation des écaillages —
T couple (couple du pignon sauf indication contraire) N∙m
T couple équivalent N∙m
T couple pour la catégorie i N∙m
T couple nominal N∙m
U somme des endommagements partiels individuels —
U endommagements partiels individuels pour la catégorie i —
u rapport d’engrenage (|z / z |) ≥ 1 —
2 1
x coefficient de déport —
Y facteur relatif à la flexion en pied de dent —
Y facteur d'épaisseur de jante —
Y facteur de profondeur de dent —
Y facteur de forme, correspondant à l’influence sur la contrainte nominale en pied de —
dent avec la charge appliquée au point le plus haut de contact uniqueY facteur de durée de vie correspondant à la contrainte en pied de dent dans les —
conditions d’essais de référenceY facteur de rugosité relative, quotient du facteur de rugosité en pied de dent —
R rel Tde la roue dentée étudiée par le facteur de rugosité de la roue dentée d’essais
de référence, Y = Y /Y
R rel T R RT
Y facteur de concentration de contrainte, pour la conversion de la contrainte nomi- —
nale en pied de dent, déterminée pour l’application de la charge au point le plus
haut de contact unique, en contrainte locale en pied de dentY facteur de concentration de contrainte, déterminé pour les dimensions de la roue —
dentée d’essais de référence standardY facteur d’angle d’hélice (contrainte en pied de dent) —
Y facteur de sensibilité relative à l’entaille, rapport du facteur de sensibilité à l’entaille —
δ rel Tde la roue dentée étudiée sur le facteur de sensibilité à l’entaille de la roue dentée
d’essais de référence standard, Y = Y /Yδ rel T δ δT
Z facteur relatif à la pression de contact —
Z , Z facteur de contact unique pour le pignon, pour la roue —
B D
2 0,5
Z facteur d’élasticité (N/mm )
Z facteur géométrique —
Z facteur lubrifiant —
Z facteur de durée de vie pour la pression de contact —
Pour les engrenages à denture extérieure a, d, d , z et z sont positifs; pour les engrenages à denture intérieure, a, d,
a 1 2d et z ont un signe négatif, z a un signe positif. Tous les diamètres calculés ont un signe négatif pour les roues dentées à
a 2 1denture intérieure.
© ISO 2019 – Tous droits réservés 3
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ISO 6336-6:2019(F)
Tableau 2 (suite)
Z facteur de durée de vie pour la pression de contact dans les conditions d’essai —
de référenceZ facteur de rugosité pour la pression de contact —
Pour les engrenages à denture extérieure a, d, d , z et z sont positifs; pour les engrenages à denture intérieure, a, d,
a 1 2d et z ont un signe négatif, z a un signe positif. Tous les diamètres calculés ont un signe négatif pour les roues dentées à
a 2 1denture intérieure.
4 © ISO 2019 – Tous droits réservés
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ISO 6336-6:2019(F)
Tableau 2 (suite)
Symboles
Symbole Description Unité
Z facteur de vitesse —
Z facteur d’écrouissage —
Z facteur de dimension (pression de contact) —
Z facteur d’angle d’hélice (pression de contact) —
Z facteur de rapport de conduite (pression de contact) —
z nombre de dents —
z nombre de dents virtuel d’une roue à denture hélicoïdale —
α angle de pression (sans indice, sur le cylindre de référence) °
β angle d’hélice (sans indice, sur le cylindre de référence) °
σ contrainte normale N/mm
σ valeur de contrainte utilisée pour décrire la courbe d’endommagement équivalent N/mm
en fatigue (Annexe B)σ contrainte de flexion de la denture N/mm
σ limite de flexion en pied de dent N/mm
σ contrainte en pied de dent pour la catégorie i N/mm
σ contrainte de flexion admissible N/mm
σ contrainte nominale de référence (flexion) N/mm
F lim
σ valeur de contrainte utilisée pour décrire la courbe S-N admissible N/mm
σ pression de contact N/mm
σ limite de pression de contact N/mm
σ pression de contact pour la catégorie i N/mm
σ pression de contact admissible N/mm
σ valeur de contrainte utilisée pour décrire la courbe S-N d’endommagement N/mm
(Annexe B)
σ niveau de contrainte admissible de référence N/mm
REF
σ pression pour la catégorie i N/mm
σ pression nominale pour la catégorie i (Annexe B) N/mm
nom,i
Pour les engrenages à denture extérieure a, d, d , z et z sont positifs; pour les engrenages à denture intérieure, a, d,
a 1 2d et z ont un signe négatif, z a un signe positif. Tous les diamètres calculés ont un signe négatif pour les roues dentées à
a 2 1denture intérieure.
4 Généralités
4.1 Détermination des spectres de charge et de contrainte
Les charges variables résultantes d’un processus de fonctionnement, d’un processus de démarrage ou
d’une utilisation sur ou proche d’une vitesse critique vont créer des variations de contrainte pour les
dentures du système d’entraînement. L’amplitude et la fréquence de ces charges dépendent de la (ou
des) machines(s) menée(s), de la (ou des) machine(s) menante(s) ou de l’entraînement ou du (ou des)
moteur(s) et des propriétés dynamiques du système masse ressort.Ces charges variables (contraintes) peuvent être déterminées par un ou plusieurs des modes opératoires
tels qu’:— un mesurage expérimental des charges en fonctionnement sur la machine en question,
— une estimation du spectre, s’il est connu pour une machine similaire ayant un mode de fonctionnement
similaire, et© ISO 2019 – Tous droits réservés 5
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ISO 6336-6:2019(F)
— un calcul par simulation dynamique des excitations extérieures connues des masses et des élasticités
du système d’entraînement, de préférence suivi d’essai expérimental afin de valider le calcul.
Pour obtenir le spectre de charge pour le calcul d’endommagement en fatigue, la gamme des charges
mesurées (ou calculées) est divisée en catégories ou classes. Chaque catégorie contient le nombre
d’occurrences de charge enregistrées dans sa plage de charges. Le nombre de catégories, habituellement
utilisé, est 64. Ces catégories peuvent être de taille identique, mais il est préférable d’utiliser des
catégories de taille plus grandes aux charges les plus faibles et des catégories de taille plus petites aux
charges les plus hautes de la gamme. De cette façon, les charges entraînant le plus d’endommagement
peuvent être limitées à moins de cycles de contrainte calculés et la conception résultante est plus exacte
relativement à la charge effective. Il est recommandé qu’une catégorie de charge nulle soit incluse ainsi
le temps total utilisé pour évaluer les engrenages correspond à la durée en service de conception. Pour
la cohérence, la méthode de présentation habituelle doit associer le couple le plus haut au numéro des
catégories le plus petit, afin que les conditions entraînant le plus d’endommagement apparaissent en
tête de n’importe quel tableau.Le comptage du cycle pour la catégorie de charge correspondant à la vapeur de charge pour la dent
la plus chargée est incrémenté à chaque répétition de charge. Le Tableau 3 indique à l’aide d’un
exemple comment appliquer les catégories de couples définies dans le Tableau 4 aux niveaux de couple
spécifiques et aux nombres de cycles correspondants.Tableau 3 — Catégories de couples/nombre de cycles — Exemple: classes 38 et 39
(voir Tableau 4)
Catégories de couples, T
Nombre de cycles, n
N⋅m
11 620 ≤ T ≤ 12 619 n = 237
38 38
10 565 ≤ T ≤ 11 619 n = 252
39 39
Il convient que les couples utilisés pour évaluer le chargement de la dent incluent les effets dynamiques
aux différentes vitesses de rotation.Ce spectre n’est valable que pour la durée mesurée ou évaluée. Si le spectre est extrapolé pour
représenter la durée de vie souhaitée, la possibilité qu’il puisse y avoir des pointes de couple pas assez
fréquentes pour avoir été enregistrées dans ce spectre mesuré doit être prise en considération. Ces
pointes transitoires peuvent avoir un effet sur la durée de vie de l’engrenage. Cependant, il pourrait
être nécessaire d’élargir la durée de vie évaluée pour intégrer les pics de charge extrêmes.
Les spectres de contrainte concernant la flexion ou les phénomènes de contact peuvent être obtenus à
partir de spectre de charge (couple).Les contraintes en pied de dent peuvent également être mesurées au moyen de jauges de contrainte
dans le profil de raccordement en pied de dent. Les contraintes de contact correspondantes peuvent
être calculées à partir des mesurages.Tableau 4 — Exemple de spectre de couple (avec des catégories de tailles différentes afin
de réduire le nombre de catégories) (voir Annexe C)Pignon
Données Temps
Couple
N ⋅ m
Cycles de charge
Catégorie n° minimum maximum s h
1 25 502 25 578 0 0,00 0 0
2 25 424 25 501 0 0,00 0 0
3 25 347 25 423 14 0,37 24 0,006 7
4 25 269 25 346 8 0,21 14 0,003 9
5 25 192 25 268 5 0,13 9 0,002 5
6 © ISO 2019 – Tous droits réservés
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ISO 6336-6:2019(F)
Tableau 4 (suite)
Pignon
Données Temps
Couple
N ⋅ m
Cycles de charge
Catégorie n° minimum maximum s h
6 25 114 25 191 8 0,21 14 0,003 9
7 25 029 25 113 16 0,42 28 0,007 8
8 24 936 25 028 8 0,21 14 0,003 9
9 24 835 24 935 5 0,13 9 0,002 5
10 24 727 24 834 11 0,29 19 0,005 3
11 24 610 24 726 16 0,42 28 0,007 8
12 24 479 24 609 19 0,50 33 0,009 2
13 24 331 24 478 14 0,37 24 0,006 7
14 24 168 24 330 14 0,37 24 0,006 7
15 23 990 24 168 11 0,29 19 0,005 3
16 23 796 23 989 15 0,39 26 0,007 2
17 23 579 23 796 31 0,81 52 0,014 4
18 23 339 23 579 28 0,73 47 0,013 1
19 23 076 23 338 36 0,94 62 0,017 2
20 22 789 23 075 52 1,36 88 0,024 4
21 22 479 22 788 39 1,02 66 0,018 3
22 22 138 22 478 96 2,51 163 0,045 3
23 21 766 22 137 106 2,77 180 0,050 0
24 21 363 21 765 49 1,28 83 0,023 1
25 20 929 21 362 117 3,05 200 0,055 6
26 20 463 20 928 124 3,24 212 0,058 9
27 19 960 20 463 61 1,59 104 0,028 9
28 19 417 19 959 140 3,65 238 0,066 1
29 18 836 19 416 148 3,86 253 0,070 3
30 18 216 18 835 117 3,05 200 0,055 6
31 17 557 18 215 121 3,16 206 0,057 2
32 16 851 17 556 174 4,46 297 0,082 5
33 16 100 16 851 185 4,83 316 0,087 8
34 15 301 16 099 196 5,11 334 0,092 8
35 14 456 15 301 207 5,40 352 0,097 8
36 13 565 14 456 161 4,20 274 0,076 1
37 12 620 13 564 168 4,38 286 0,079 4
38 11 620 12 619 237 6,18 404 0,112 2
39 10 565 11 619 252 6,58 429 0,119 2
40 9 457 10 565 263 6,86 449 0,124 7
41 8 294 9 456 275 7,18 468 0,130 0
42 7 070 8 294 178 4,65 303 0,084 2
43 5 783 7 069 103 2,69 176 0,048 9
44 4 434 5 782 7 0,18 12 0,003 3
45 3 024 4 434 0 0,00 0 0
46 1 551 3 023 0 0,00 0 0
© ISO 2019 – Tous droits réservés 7
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ISO 6336-6:2019(F)
Tableau 4 (suite)
Pignon
Données Temps
Couple
N ⋅ m
Cycles de charge
Catégorie n° minimum maximum s h
47 1 1 550 0 0,00 0 0
48 0 0 0 0,00 6 041 469 1 678,2
Total ≥ 3 832 100,0 6 048 000 1 680
4.2 Calcul général de la durée en service
La durée en service calculée est basée sur la théorie que chaque cycle de charge (chaque tour) est
endommageante pour l’engrenage. L’étendue des endommagements dépend du niveau de contrainte et
peut être voisin de zéro pour les niveaux de contrainte les plus faibles.La durée de vie calculée en fatigue à la flexion ou à la pression de contact d’un engrenage (écaillage)
est une mesure de sa capacité à cumuler des endommagements partiels jusqu’à ce que la défaillance se
produise.Les calculs de tenue à la fatigue exigent de connaître:
a) le spectre de contrainte,
b) les propriétés en fatigue du matériau, et
c) une méthode de cumul des endommagements.
Le spectre de contrainte est traité en 5.1.
Les valeurs de tenue basées sur les propriétés en fatigue du matériau sont choisies à partir des
courbes S-N applicables. De nombreux échantillons doivent subir un essai en les chargeant de manière
répétée sur un niveau de contrainte unique jusqu’à l’apparition de la défaillance. Cela donne, après
une interprétation statistique pour une probabilité donnée, un nombre de cycles jusqu’à la défaillance
caractéristique pour ce niveau de contrainte....
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