请问谁知道Halt的随机振动怎么算加速因子

没听过Halt试验中的随机振动计算加速因子 做HASS时，根据HALT试验得到的值，取一个百分比而已。 楼主可以再把问题描述清楚一些，为什么要计算随机振动的加速因子。目的是什么，以你的理解，大概如何计算？？？？

有正常的振动的加速因子计算吗？？？？？想交流一下

忘记在哪里看到过的 振动的加速因子使用G值用逆幂模型(PowerLaw)进行计算的

[b]回复[url=http://www.kekaoxing.com/club/redirect.php?goto=findpost&pid=77134&ptid=8097]4#[/url][i]fuckit[/i][/b] 了解一下,希望有更多的高手如fuckit一样,来介绍介绍

A_V=T_Use/T_Stress=(W_Stress/W_Use)^(M_b) (W_Stress/W_Use)^(M_b)=(G_(f_Stress)/G_(f_Use))^(2M_b) Ln(tf)=C-M_bLn(W) Where, A_V=vibrationaccelerationfactor T_Stress=vibrationduration T_Use=vibrationduration(nominal) W=randomvibrationinputPSDacross theresonancebandwidth(G2/Hz) W_StressisthePSDteststressand W_UsenominalusePSD G_f=resonantGsinusoidvibrationlevel M_b=b/2wherebisthefatigueparameter tf=timetofailure C=constant

Example:UsingtheVibrationmodel [b]Problem:[/b] Estimatethetesttimetosimulate10yearsoflifeinthefieldforanassembly thatistestedtoaLevel4PSDrandomvibrationtestcondition,shownin below[b]Remark[/b]description.Itisestimatedthattheassemblywillundergoaworst-caseLevel1- typerandomvibrationexposure1percentoftheassembly’slife.Therestof theassembly’slifeisrelativelybenignintermsofvibrationexposure. [b]Solution:[/b] First,usetheexpressionin[b]previousletter[/b]tofindthevibrationaccelerationfactor.SinceLevel4hasa PSDof0.12G2/Hz,thenLevel1is0.03G2/Hz. Therefore, AV=(WStress/WUse)Mb=(0.12/0.03)4=256. In10years,thedevicewillbeexposedtoaLevel1vibrationforabout87,600×0.01=876hours. Therefore,thenumberoftestcyclestosimulatethisis TStress=TUse/AV=876/256=3.5hours. [b]Remark:CommonrandomvibrationtestsaremostfrequentlyspecifiedintermsofPowerSpectralDensity(PSD)levels[/b] Level2:Avg.PSD=0.06G2/HZ(Content11GRMS) Level4:Avg.PSD=0.12G2/HZ(Content15.5GRMS) Level8:Avg.PSD=0.24G2/HZ(Content21.9GRMS) Level16:Avg.PSD=0.48G2/HZ(Content31GRMS)

谢谢，学习了；有相关案例就更好了

[quote]A_V=T_Use/T_Stress=(W_Stress/W_Use)^(M_b) (W_Stress/W_Use)^(M_b)=(G_(f_Stress)/G_(f_Use))^(... [size=2][color=#999999]ice_fang发表于2010-7-1010:56[/color][url=http://www.kekaoxing.com/club/redirect.php?goto=findpost&pid=78194&ptid=8097][/url][/size][/quote] 请教：该公式源于哪个标准或文献？

[b]回复[url=http://www.kekaoxing.com/club/redirect.php?goto=findpost&pid=78195&ptid=8097]7#[/url][i]ice_fang[/i][/b] 真的非常感谢你的分享！仔细看了下你分享的内容，有些问题还需要向你请教： 1）M_b=b/2wherebisthefatigueparameter这个参数怎么确定？比如你举的例子中AV=(WStress/WUse)Mb=(0.12/0.03)4=256的[b]4[/b]是怎么确定的？ 2）G_f=resonantGsinusoidvibrationlevel怎么用的是正玄共振等级？不是随机振动么？正玄共振等级如何确定其值？ 3）C=constant如何取值？ 4）PSDLevel的值是实验根据具体产品得出还是共用的？比如 Level2:Avg.PSD=0.06G2/HZ(Content11GRMS) Level4:Avg.PSD=0.12G2/HZ(Content15.5GRMS) Level8:Avg.PSD=0.24G2/HZ(Content21.9GRMS) Level16:Avg.PSD=0.48G2/HZ(Content31GRMS) 还有你Level1PSD=0.03G2/HZ是推算的么？还是试验得出的？ 5）最后一个问题，和楼上一个兄弟一样的，就是不知道兄弟这些公式和资料是出自什么文件上的阿？能共享下么？ [b]真的再次感谢！！！！！！！[/b]

DearAll, Sorry,mybossoncegivemeapaperliteraturewhichdescribevibrationmodel.SoIshareitwithall. Iquoteasectionforyourreference. InVibration,devicesaremountedonadynamicshakertableandsubjecttoeitherarandomorsinusoidal-typevibrationprofile.CommonrandomvibrationtestsaremostfrequentlyspecifiedintermsofPowerSpectralDensity(PSD)levels(seebelowFigure).FigureillustratesthepossiblePSDtestprofilelevelsrelatedtoasimilarparticularuseenvironment.ThePSDfunctiondescribesthedistributionofvibrationenergywithrespecttofrequency.TheamountoftimecompressionthatcanbeaccomplishedisrelatedtothePSDtestlevelanduselevel.Estimatesoftimecompressioncanbemadeoncetheuselevelestimateandspectraldensityprofileareestablished.Thetraditionalclassicaltime-compressionmodel(MIL-STD810E)isapowerlawmodel(seebelowFigure).Inapplyingthismodel,itisimportanttounderstandthefailuremechanismsince,inarandomvibration-loadingenvironment,theresonanceofthematerialcandominatethefatiguelife.Here,maximumvibrationamplitudesandstressoccur.However,fatiguefailuresarenotalwaysdominatedbythefundamentalresonancemode.Inpractice,manyofthestresspeaksintheuseenvironmentmayfallbelowthefatiguelimitofthematerial,whileotherswillbeabovethefatiguelimit.Itfollowsthatanacceleratedlifetestbaseduponthismodelshouldinherentlybeconservative.However,becausemostofthefatiguedamageoccursatthehigheststresspeaksinboththetestandinactualuse,thedegreeofconservatismisnotexcessive.AsnotedinbelowFigure,thePSDisinunitsofG2/Hz.ThesquareoftheGstresslevelattheresonancefrequencyisdirectlyproportionaltothePSDlevel(W~G2),sothemodelcanbeputintermsofeitherrandomorsinusoidal-resonanceG-stressloading.Inthemodel,thefatigueparameterisrelatedtoexperimentalslopeofthestresstocyclestofailuredata.Thisexponentvariesdependingonthefatiguelifeofthematerialsinvolved.Forexample,thevalueofb≈5iscommonlyusedforelectronicboards.However,conservativevalueforthefatigueparameterbisabout8(e.g.,Mb=4).MILSTD-810E(514.4-46)recommendsb=8forrandomloading. [attach]6890[/attach]