1、ANSI/AGMA ISO 6336-6-A08Reaffirmed March 2014American National StandardCalculation of Load Capacity ofSpur and Helical Gears -Part 6: Calculation of ServiceLife Under Variable LoadANSI/AGMAISO6336-6-A08iiCalculation of Load Capacity of Spur and Helical Gears - Part 6:Calculation of Service Life Unde
2、r Variable LoadANSI/AGMA ISO 6336-6-A08ApprovalofanAmericanNationalStandardrequiresverificationbyANSIthattherequire-ments for due process, consensus, and other criteria for approval have been met by thestandards developer.Consensusisestablishedwhen,inthejudgmentoftheANSIBoardofStandardsReview,substa
3、ntial agreement has been reached by directly and materially affected interests.Substantialagreementmeansmuchmorethanasimplemajority,butnotnecessarilyuna-nimity. Consensus requires that all views and objections be considered, and that aconcerted effort be made toward their resolution.TheuseofAmerican
4、NationalStandardsiscompletelyvoluntary;theirexistencedoesnotin any respect preclude anyone, whether he has approved the standards or not, frommanufacturing, marketing, purchasing, or using products, processes, or procedures notconforming to the standards.The American National Standards Institute doe
5、s not develop standards and will in nocircumstances give an interpretation of any American National Standard. Moreover, noperson shall have the right or authority to issue an interpretation of an American NationalStandardinthenameoftheAmericanNationalStandardsInstitute. Requestsforinterpre-tation of
6、 this standard should be addressed to the American Gear ManufacturersAssociation.CAUTION NOTICE: AGMA technical publications are subject to constant improvement,revision, or withdrawal as dictated by experience. Any person who refers to any AGMAtechnicalpublicationshouldbesurethatthepublicationisthe
7、latestavailablefromtheAs-sociation on the subject matter.Tablesorotherself-supportingsections maybereferenced. Citationsshouldread: SeeANSI/AGMAISO6336-6-A08,CalculationofLoadCapacityofSpur andHelicalGears -Part6: CalculationofServiceLife UnderVariableLoad, publishedbytheAmericanGearManufacturers As
8、sociation, 500 Montgomery Street, Suite 350, Alexandria, Virginia22314, http:/www.agma.org.Approved May 20, 2008ABSTRACTThisstandardspecifiestheinformationandstandardizedconditionsnecessaryforthecalculationoftheservicelife(orsafetyfactorsforarequiredlife)ofgearssubjecttovariableloading.Whilethemetho
9、dispresentedinthecontextofISO6336andcalculationoftheloadcapacityofspurandhelicalgears,itisequallyapplicabletoothertypes of gear stress.Published byAmerican Gear Manufacturers Association500 Montgomery Street, Suite 350, Alexandria, Virginia 22314Copyright 2008 by American Gear Manufacturers Associat
10、ionAll rights reserved.No part of this publication may be reproduced in any form, in an electronicretrieval system or otherwise, without prior written permission of the publisher.Printed in the United States of AmericaISBN: 978-1-55589-928-8AmericanNationalStandardANSI/AGMA ISO 6336-6-A08AMERICAN NA
11、TIONAL STANDARDiii AGMA 2008 - All rights reservedContentsPageForeword iv1 Scope 12 Normative references 13 Terms, definitions, symbols and abbreviated terms 1.4 General 15 Calculation according to ISO 6336 of service strength on basis ofsingle-stage strength 6Bibliography 20AnnexesA Determination o
12、f application factor, KA, from given load spectrum usingequivalent torque, Teq8B Guide values for application factor, KA12.C Example calculation of safety factor from given load spectrum 15Figures1 Example for a cumulative stress spectrum 42 Torque spectrum and associated stress spectrum with S-N 5.
13、3 Accumulation of damage 5.4 Flow chart for determination of calculated safety factor for given loadspectrum 7.Tables1 Torque classes/numbers of cycles - Example: classes 38 and 39 22 Example of torque spectrum (with unequal bin size for reducing numberof bins) 2.3 Torque classes/numbers of cycles -
14、 Example: classes 38 and 39 6ANSI/AGMA ISO 6336-6-A08 AMERICAN NATIONAL STANDARDiv AGMA 2008 - All rights reservedForewordThe foreword, footnotes and annexes, if any, in this document are provided forinformational purposes only and are not to be construed as a part of ANSI/AGMA ISO6336-6-A08,Calcula
15、tionofLoadCapacityofSpurandHelicalGears -Part 6: Calculationof Service Life Under Variable Load.It is recommended that the cumulative fatigue damage criteria proposed by Miner (MinersRule) beemployed toevaluate the effects of variable loading onthe lifeof gearing. MinersRule was developed in 1945 by
16、 M. A. Miner to assess the effects of cumulative fatiguedamage under repeated and variable intensity loads. The method was developed foraircraft part design and tested for aluminum alloys byMiner, but was subsequently verifiedfor steel by others. It was commonly used in vehicle gearing design. An ex
17、planation ofMiners Rule was included in AGMA 170.01 (1976), Design Manual for Vehicle Spur andHelical Gears, and the calculation method was later included as annex D in AGMA 218.01(1982), AGMA Standard for Rating and Pitting Resistance and Bending Strength of Spurand Helical Involute Gear Teeth.In t
18、he 1990s, AGMA proposed a project to ISO Technical Committee 60 (TC 60) as aninternational standard. However, agreement could not be reached on the total content.Therefore,anISOTechnicalReportoftype2waspreparedbylSO/TC60,Subcommittee2for gear capacity calculation. The resulting document, ISO/TR 1049
19、5, Cylindrical gears -Calculation of service life under variable load - Conditions for cylindrical gears inaccordance with ISO 6336, was published in 1997.In 2002, a revision of ISO/TR 10495 was begun, agreement was obtained and the workresulted in the new ISO standard, ISO 6336-6 Calculation of loa
20、d capacity of spur andhelicalgears -Part6:Calculationofservicelifeundervariableload,whichwaspublishedinAugust 2006.ANSI/AGMA ISO 6336-A08 represents an identical adoption of ISO 6336-6:2006, andincludes Technical Corrigendum 1 (August 1, 2007).The first draft of ANSI/AGMA ISO 6336-6-A08 was made in
21、February, 2007. It wasapproved by the AGMA membership in March, 2008. It was approved as an AmericanNational Standard on May 20, 2008.Suggestions for improvement of this standardwill be welcome. Theyshouldbesent totheAmericanGearManufacturersAssociation,500MontgomeryStreet,Suite350,Alexandria,Virgin
22、ia 22314.ANSI/AGMA ISO 6336-6-A08AMERICAN NATIONAL STANDARDv AGMA 2008 - All rights reservedPERSONNEL of the AGMA Helical Gear Rating CommitteeChairman: John V. Lisiecki Rexnord Industries Gear OperationsVice Chairman: Michael B. Antosiewicz Rexnord Industries Gear Operations.ACTIVE MEMBERSK.E. Ache
23、son Gear Works - Seattle, Inc.J.B. Amendola, Sr. Artec Machine Systems.T.A. Beveridge Caterpillar, IncP. Biggert Horsburgh pinion at 35.2r/min assumes one raise and lower per week.The torques used to evaluate tooth loading shouldinclude the dynamic effects at different rotationalspeeds.This spectrum
24、 is only valid for the measured orevaluated time period. If the spectrum is extrapo-latedtorepresenttherequiredlifetime,thepossibilitythat there might be torque peaks not frequentenough to be evaluated in that measured spectrummust be considered. These transient peaks canhave an effect on the gear l
25、ife. Therefore, theevaluated time period could have to be extended tocapture extreme load peaks.Stress spectra concerning bending and pitting canbe obtained from the load (torque).Scuffing resistance must be calculated from theworst combination of speed and load.Wear is a continuous deterioration of
26、 the tooth flankand must be considered separately.Toothrootstresscanalsobemeasuredbymeansofstrain gauges in the fillet. In this case, the deratingfactors should be taken into account using theresults of the measurements. The relevant contactstress can be calculated from the measurements.4.3 General
27、calculation of service lifeThecalculatedservicelifeisbasedonthetheorythatevery load cycle (every revolution) is damaging tothe gear. The amount of damage depends on thestress levelandcanbeconsidered as zero for lowerstress levels.Thecalculatedbendingorpittingfatiguelifeofagearis a measure of its abi
28、lity to accumulate discretedamage until failure occurs.The fatigue life calculation requires- the stress spectrum,- material fatigue properties, and- a damage accumulation method.ANSI/AGMA ISO 6336-6-A08 AMERICAN NATIONAL STANDARD4 AGMA 2008 - All rights reservedThestressspectrumisdiscussedin5.1.Str
29、engthvaluesbasedonmaterialfatiguepropertiesare chosen from applicable S-N curves. Manyspecimensmustbetestedbystressingthemrepeat-edly at one stress level until failure occurs. Thisgives, after a statistical interpretation for a specificprobability, a failure cycle number characteristic ofthis stress
30、 level. Repeating the procedure atdifferent stress levels leads to an S-N curve.Anexampleofacumulativestressspectrumisgivenin Figure 1. Figure 2 shows a cumulative contactstress spectrum with an S-N curve for specificmaterial fatigue properties.Linear, non-linear and relative methods are used.Furthe
31、r information can be found in the literature.4.4 Palmgren-Miner ruleThePalmgren-Minerrule - inadditiontootherrulesor modifications - is a widely used linear damageaccumulation method. It is assumed that thedamaging effect of each stress repetition at a givenstress level is equal, which means the fir
32、st stresscycle at a given stress level is as damaging as thelast.The Palmgren-Miner rule operates on the hypothe-sis that the portion of useful fatigue life used by anumber of repeated stress cycles at a particularstress is equal to the ratio of the total number ofcycles during the fatigue life at a
33、 particular stresslevel according to the S-N curve established for thematerial. For example, if a part is stressed for 3000cycles at a stress level which would cause failure in100 000 cycles, 3% of the fatigue life would beexpended. Repeated stress at another stress levelwould consume another simila
34、rly calculated portionof the total fatigue life.Theusedmaterialfatiguecharacteristicsandendur-ance data should be related to a specific andrequired failure probability, e.g., 1%, 5% or 10%.When 100% of the fatigue life is expended in thismanner,thepartcouldbeexpectedtofail. Theorderin which each of
35、these individual stress cycles isapplied is not considered significant in Palmgren-Miner analysis.FailurecouldbeexpectedwheniniNi= 1.0(1)whereniis the number of load cycles for bin i;Niisthenumberofloadcyclestofailureforbini(taken from the appropriate S-N curve).KeyX cumulative number of applied cyc
36、lesYstresa Load spectrum, ni, total cycles.iniaFigure 1 - Example for a cumulative stress spectrumANSI/AGMA ISO 6336-6-A08AMERICAN NATIONAL STANDARD5 AGMA 2008 - All rights reservedNOTES:1. The representation of the cumulative stress spectrum entirely below the S-N curve doesnot imply that the part
37、will survive the total accumulative number of stress cycles. Thisinformation can be gained from a presentation as shown in figure 3.2. The value Gis either HGor FG.12345N3Log Nn3Log,logTG(N)T1T2T3T4T5Figure 2 - Torque spectrum and associated stress spectrum with S-NKeyX number of load cycles, NLYstr
38、esNOTE Fromthispresentationitcanbeconcludedwhetherthepartwillsurvivethetotalnumberof stress cycles.a 100% damage.b 10% damage.c 1% damage.103104105106107108109abc123Figure 3 - Accumulation of damageANSI/AGMA ISO 6336-6-A08 AMERICAN NATIONAL STANDARD6 AGMA 2008 - All rights reservedIf there is an end
39、urance limit (upper, horizontal linebeyond the knee in figure 2), the calculation is onlydone for stresses above this endurance limit.If the appropriate S-N curve shows no endurancelimit (lower line beyond the knee in Figure 2), thecalculation must be done for all stress levels. Foreach stress level
40、, i, the number of cycles to failure,Ni, have to be taken from the corresponding part ofthe S-N curve.5 Calculation according to ISO 6336 of servicestrength on basis of single-stage strength5.1 Basic principlesThis method is only valid for recalculation. Itdescribes the application of linear cumulat
41、ive dam-age calculations according to the Palmgren-Minerrule (see 4.4) and has been chosen because it iswidelyknownandeasytoapply;thechoicedoesnotimplythatthemethodissuperiortoothersdescribedin the literature.Fromtheindividualtorqueclasses,thetorquesattheupper limit of each torque class and the asso
42、ciatednumbers of cycles shall be listed (see table 3 for anexample).Table 3 - Torque classes/numbers of cycles -Example: classes 38 and 39Upper limit of torqueclass1), Ti,NmNumber of cycles, niT381Miner sum 1,Ui=niNii- For bending stress:YNTi=FiFPiNi=YNTi 49.91250338(3)106if YNTi 1Ni= YNTi2.5 8.7372
43、4908103if YNTi 1,Ui=niNiiC.7 Calculate the Miner sumSum up each damage part of the spectra accordingto equation 3. The values are given at the foot oftables C.2 and C.3.C.8 Iterate the safety factorFollowing figure 7, by iterating, change the safetyfactor up or down as needed and recalculateaccordin
44、g to C.4 to C.7 until the sum of damageparts, Ui, is between 0.99 and 1.00. For thisexample, the spreadsheet program function wasused to do the iterations. For 30 years of operation,thispinionhasasafetyfactorof1.428inpittingandasafety factor of 1.324 in bending.ThevaluesaregivenintablesC.2andC.3.The
45、 Woehler-damage curves are shown infigure C.1.ANSI/AGMA ISO 6336-6-A08AMERICAN NATIONAL STANDARD17 AGMA 2008 - All rights reservedTable C.2 - Example for calculation of pitting safety factor from load spectrum safety factor 1.428Bin No.PiniontorqueTime over70 daysPinionspeedStresscycles in30 yearsFa
46、ce loadfactorContactstressLife factorCycles tofailureDamagepartsT1n1N KHH SHZNTNfUikN m s r/min N/mm2(N/Nf)1 25.6 0.00E+00 35.2 0.000E+00 0.000E+002 25.5 0.00E+00 35.2 0.000E+00 0.000E+003 25.4 2.40E+01 35.2 2.203E+03 1.305 2350 1.613 8.990E+04 2.450E-024 25.3 1.40E+01 35.2 1.285E+03 1.305 2347 1.61
47、0 9.172E+04 1.401E-025 25.3 9.00E+00 35.2 8.259E+02 1.305 2343 1.608 9.361E+04 8.824E-036 25.2 1.40E+01 35.2 1.285E+03 1.305 2340 1.606 9.551E+04 1.345E-027 25.1 2.80E+01 35.2 2.570E+03 1.305 2336 1.603 9.749E+04 2.636E-028 25.0 1.40E+01 35.2 1.285E+03 1.305 2332 1.600 9.970E+04 1.289E-029 24.9 9.00
48、E+00 35.2 8.259E+02 1.305 2328 1.597 1.022E+05 8.083E-0310 24.8 1.90E+01 35.2 1.744E+03 1.305 2323 1.594 1.050E+05 1.661E-0211 24.7 2.80E+01 35.2 2.570E+03 1.305 2318 1.591 1.080E+05 2.378E-0212 24.6 3.30E+01 35.2 3.028E+03 1.305 2312 1.587 1.115E+05 2.717E-0213 24.5 2.40E+01 35.2 2.203E+03 1.305 23
49、06 1.583 1.155E+05 1.907E-0214 24.3 2.40E+01 35.2 2.203E+03 1.305 2299 1.578 1.202E+05 1.832E-0215 24.2 1.90E+01 35.2 1.744E+03 1.305 2292 1.573 1.256E+05 1.388E-0216 24.0 2.60E+01 35.2 2.386E+03 1.305 2283 1.567 1.320E+05 1.808E-0217 23.8 5.20E+01 35.2 4.772E+03 1.305 2274 1.560 1.392E+05 3.428E-0218 23.6 4.70E+01 35.2 4.313E+03 1.305 2264 1.553 1.479E+05 2.916E-0219 23.3 6.20E+01 35.2 5.690E+03 1.305 2252 1.545 1.583E+05 3.595E
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