参考公开培训

1、OptiStruct 疲劳分析功能.cn Hotline: 4006-196-186 2017 Altair Engineering, Inc. Proprietary and.s.主要内容疲劳破坏机理疲劳分析方法疲劳影响疲劳低周疲劳无限焊点疲劳焊缝疲劳疲劳随机振动疲劳扫频疲劳2OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳？在某点或某些点承受扰动载荷（应力、应变），且在足够多的循环扰动作用之后形成裂纹或完全断裂的材料中所发生的局部结构变化的发展过程，称为疲劳。特点：在远低于静

2、强度的载荷下(eg.20%60%uts)，结构失效。Classic appearance of a fatigue cracked railway axle from Glynn, 18443OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳破坏机理金属疲劳破坏三阶段裂纹萌生疲劳裂纹扩展失稳断裂4OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳破坏阶段一疲劳裂纹萌生金

3、属在循环载荷作用下，在薄弱的晶粒间沿着晶面产生塑形应变，金属晶粒产生滑移，金属表面出现滑移线，滑移线随循环次数增加而汇集成表面滑移带，发展成驻留滑移带，最终形成裂纹ExtruUndeformed materialruLoadingUnloading5OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳破坏阶段一疲劳裂纹萌生驻留滑移带6OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary an

4、d.s.疲劳破坏阶段一疲劳裂纹萌生微裂纹的产生微裂纹一般产生于表面微裂纹的产生是一个随机过程Magnified Surface10 m7OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳破坏阶段二疲劳裂纹扩展阶段一滑移面趋向大致与主应力轴成450，这个阶段裂纹扩展很慢。滑移带上往往萌生有很多 绝大多数裂纹很早停止扩展。裂纹，随着循环载荷的继续施加，少数微裂纹互相连接超过几十微米长度。阶段二裂纹的扩展方向由开始与外加应力成接近450，逐渐转向与拉伸应力垂直。只剩下一条主裂纹裂纹扩展较

5、第一阶段快阶段一向阶段二转换的裂纹长度一般不超过十分之几个毫米8OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳破坏阶段三失稳断裂裂纹扩展到临界尺寸，裂纹尖端的应力强度因子达到临界值，构件突然失稳破坏9OptiStruct Fatigueysis, Ver2017Brittle脆性材料Ductile延展性材料 2017 Altair Engineering, Inc. Proprietary and.s.疲劳分析方法通过光滑试件试验，建立应力、应变曲线将构件上的点类比光滑试件，通

6、过构件上的等效应力幅、应变幅查询应力、应变曲线，得到构件疲劳由于构件与标准试件的尺寸、载荷、表面处理等的差异，在疲劳评估时需要进行相应的修正。10OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.影响疲劳的载荷形式的影响材料的疲劳随加载形式的不同而不同，在同等的应力水平下，疲劳有如下趋势N(弯）N(拉）N(扭）11OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.影响疲劳尺寸效

7、应的大尺寸构件的疲劳抵抗力低于小尺寸试件，这是由于体积越大，存在缺陷或薄弱处的可能就越大，在相同的应力分布下，试件尺寸越大，高应力区域材料体积就越大，构件的疲劳就越低。12OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.影响疲劳的表面光洁度的影响疲劳裂纹的萌生总是从表面开始，若试件表面粗糙，将使局部应力集中的程度加大，裂纹萌生能就是潜在的裂纹源。缩短。表面加工时的划痕、碰伤可13OptiStruct Fatigueysis, Ver2017 2017 Altair Engineeri

8、ng, Inc. Proprietary and.s.影响疲劳的表面处理的影响疲劳裂纹总是于表面。为了提高疲劳性能，除了改善光洁度以外，常常采用各种方法在构件的高应力表面引入压缩残余应力，以达到提高疲劳的目的。表面渗碳或渗氮可使钢材疲劳极限提高一倍热轧或锻造会使材料表面脱碳，强度下降并在材料表面引入拉伸残余应力，可使材料疲劳极限降低50%。14OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.影响疲劳的平均应力的影响疲劳破坏是裂纹萌生扩展的过程在受压平均应力作用下，裂纹处于闭合状态，抑

9、制了裂纹扩展在受拉平均应力作用下，裂纹处于张开状态，裂纹尖端存在应力集中，促进了裂纹扩展15OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳分类疲劳应力在弹性范围内低周疲劳局部应力进入塑性无限疲劳任意一个循环的应力都不会引起材料的损伤低周疲劳疲劳无限cycle103108116OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.单轴疲劳VS多轴疲劳比例加载应轴不会发生变化最

10、大主应力、最大剪应力面不变裂纹面容易采用单轴疲劳分析或多轴比例加载疲劳分析非比例加载应轴会发生变化最大主应力、最大剪应力面发生变化裂纹面不容易采用多轴疲劳分析方法17OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳分析基础应力/应变幅平均应力应力比 R min maxm2 2 a a218OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳分析基础雨流计数雨流(Rain

11、flowCounting)可以将任意幅值的载荷历程进行分组，将任意载荷历程转换为若干恒定幅值的载荷组。每个载荷组具有确定的恒定的幅值、平均应力和循环次数19OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳分析基础三点法雨流计数示例去除中间点，只保留峰值点。以最大值所在点为起始点，将最大值之前的点移至序列末尾DS1=|S1-S2|,DS2=|S2-S3|,如果DS11, failed)Total Life = 1/Total Damage疲劳之单轴疲劳 2017 Altair En

12、gineering, Inc. Proprietary and Confidential. All rights reserved.S-N疲劳试验准备若干根标准试件（30根左右）确定试验应力水平（45级）确定每一应力水平上的试件数（68件）进行试验，记录试验数据试验数据服从对数正态分布画出P-S-N曲线23OptiStruct Fatigue Analysis, Version 2017疲劳单边置信统计结果P(x)Certainty of Survival 生存概率-399.87%-297.73%-84.15%050.00%15.85% 2017 Altair Engineering, Inc

13、. Proprietary and.s.P-S-N曲线概率S-N曲线一般看到的曲线是默认50%存活概率时的曲线，即一般实验得到的概率曲线存活概率值越高，曲线越靠下。24OptiStruct Fatigueysis, Ver2017Certa y of Survival increase50% Certa y of Survival 2017 Altair Engineering, Inc. Proprietary and.s.S-N的直线拟合法OptiStruct使用的应力疲劳公式为：S SRI1 N b式中S是应力范围SRI1是纵轴截距b是斜率，为小于0的值 blog SRI1log Slo

14、g N25OptiStruct Fatigueysis, Ver2017SRI1 2017 Altair Engineering, Inc. Proprietary and.s.S-N拟合曲线的数学表达式及含义更一般的S-N曲线是双折线形式，需要定义截距SRI1，第一斜率b1，第二斜率b2，转换点NC126OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.常用材料S-N曲线27OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering

15、, Inc. Proprietary and.s.等效应力对于脆性材料的疲劳破坏，多采用带绝对值的最大主应力准则对于延性材料，多采用带符号的Mises应力准则。也提供了其他的疲劳评价准则。28OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.平均应力修正Goodman修正拉平均应力都会缩短疲劳压平均应力会延长疲劳改进的Goodman修正只有受拉平均应力会缩短疲劳Gerber修正拉、压平均应力都会缩短疲劳29OptiStruct Fatigueysis, Ver2017 2017 Alt

16、air Engineering, Inc. Proprietary and.s.疲劳分析流程 - step1:应力叠加f1ijF1(t)f2ijF2(t)30OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳分析流程- step 2 : 等效应力由应力张量曲线等效应力曲线31OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳分析流程 - step 3对等效应力曲线进行雨

17、流计数:雨流计数32OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.疲劳分析流程 - step 4 :计算损伤根据平均应力及应力幅值，查询SN曲线，得到每个循环的损伤累积所有循环的损伤，得到整个载荷历程损伤33OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.OptiStruct疲劳卡片结构SUBCASEFATDEFFATPARMFATSEQPFATFATEVNTMATFAT

18、FOADTABFAT34OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.OptiStruct疲劳卡片SUBCASETABFAT定义载荷历程FATDEFFATPARMFATSEQPFATFATEVNTMATFATFOADTABFAT35OptiStruct Fatigueysis, Ver2017(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)TABFATIDY1Y2Y3Y4Y5Y6Y7Y8 2017 Altair Engineering, Inc. Proprietar

19、y and.s.SUBCASEOptiStruct疲劳卡片FATDEFFATPARMFATSEQFOAD由载荷历程生成应力、应变历程PFATFATEVNTMATFATFOADTABFATijf1F1(t)36OptiStruct Fatigueysis, Ver2017(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FOADIDTIDLCIDLDMScaleOffset 2017 Altair Engineering, Inc. Proprietary and.s.SUBCASEOptiStruct疲劳卡片FATEVNT应力、应变历程的叠加FATDEFFATPARMFATSEQP

20、FATFATEVNTMATFATFOADTABFAT37OptiStruct Fatigueysis, Ver2017FLOAD2FLOAD1(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATEVNTIDFLOAD1FLOAD2FLOAD3FLOAD4FLOAD5FLOAD6FLOAD7FLOAD8 2017 Altair Engineering, Inc. Proprietary and.s.SUBCASEOptiStruct疲劳卡片FATSEQ定义载荷序列FATDEFFATPARMFATSEQPFATFATEVNTMATFATFOADTABFAT38OptiStruct

21、Fatigueysis, Ver2017(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATSEQIDFID1N1FID2N2FID3N3FID4N4FID5N5 2017 Altair Engineering, Inc. Proprietary and.s.FATSEQ示例39OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.SUBCASEOptiStruct疲劳卡片FATPARM疲劳分析控制参数FATDEFFATPARMFATSEQPFATFATEVNTMATFAT

22、FOADTABFAT40OptiStruct Fatigueysis, Ver2017TYPE分析类型，SN/ENCOMBINE等效应力、应变CORRECTION平均应力修正FEM分析中应力STRESURVCERTSN/EN曲线的存活概率(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATPARMIDTYPEMAXLFATSTRESSCOMBINECORRECTPLASTICSURFSTSSTRERAINFLOWRTYPEGATERELPRPLDCHKMDMGMDLDM1DM2DM3CERYSURVCERTFOSFOSTYPE 2017 Altair Engineering,

23、In SUBCASE d.s.FATDEFFATPARMFATSEQOptiStruct疲劳卡片MATFAT定义材料的疲劳属性PFATFATEVNTMATFATFOADTABFATUNIT材料属性所采用的YS屈服极限UTS受拉断裂时应力SR1疲劳强度系数B1疲劳强度指数Nc1一段SN曲线的疲劳极限，二段SN曲线的转折点B2疲劳强度指数41FL疲劳极限OptiStruct F(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)MATFATMIDUNITSICYSUTSSNSR1B1NC1B2FLSEFINDLEYTFN 2017 Altair Engineering, Inc. Pro

24、prietary and.s.SUBCASEOptiStruct疲劳卡片PFATFATDEFFATPARMFATSEQPFATFATEVNTMATFATFOADTABFAT42OptiStruct Fatigueysis, Ver2017Layer壳单元疲劳分析所在层Finish表面光洁度Treatment表面处理Kf疲劳强度影响因子(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)PFATIDLayerFinishTreatmentKfSPTFAILALPHA 2017 Altair EProprietary and.s.SUBCASEOptiStruct疲劳卡片FATDEFFA

25、TDEFFATPARMFATSEQPFATFATEVNTMATFATFOADTABFAT43OptiStruct Fatigueysis, Ver2017TOPSTR应力比，当单元的应力大于最大应力乘以该应力比值时，该单元会进行疲劳分析ELSID#定义疲劳分析单元(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATDEFIDTOPSTRPFATID1ELSID2PFATID2ELSID3PFATID3ELSESID1ELSID4PFATID4疲劳之多轴疲劳 2017 Altair Engineering, Inc. Proprietary and.s.多轴疲劳破坏模式多轴疲劳裂

26、纹位置多轴疲劳裂纹总是萌生于表面。多轴疲劳只关注表面应力多轴疲劳裂纹方向由于剪切，裂纹沿与表面成450面成核由于拉伸，裂纹沿与表面垂直方向扩展4545gon 2017 2017 Altair Engineering, Inc. Proprietary and.s.多轴疲劳评估方法临界平面法每隔100，搜索一个临界面，根据临界面上的应力应变评估该临界面上的疲劳最终的疲劳。为最的临界面上的46OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.多轴疲劳评估方法Goodman方法评估由于受拉产

27、生的垂直于表面的裂纹萌生及扩展。SeSaSmSu平均应力修正后的等效应力幅临界面上应力幅 临界面上平均应力 UTS47OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.多轴疲劳评估方法Findley方法评估由于剪切导致的斜裂纹疲劳临界面上剪应力幅临界面上法向应力48OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.多轴疲劳分析流程49OptiStruct Fatigueysis

28、, Ver2017ProportionalYesLoading?NoEndAssess damage. Planesearch is requiredAssess damage. No Plane search is required.Elastic Stress 2017 Altair Engineering, Inc. Proprietary and.s.多轴疲劳卡片设置MATFAT50OptiStruct Fatigueysis, Ver2017FINDLEYFindley评估方法k值TFN剪切疲劳强度系数(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)MATFATMIDU

29、NITSICYSUTSSNSR1B1NC1B2FLSEFINDLEYTFN 2017 Altair Engineering, Inc. Proprietary and.s.多轴疲劳卡片设置FATPARM51OptiStruct Fatigueysis, Ver2017MAXLFAT多轴疲劳分析开关SURFSTS在实体单元外面创建非常薄的薄膜应力壳单元，用于多轴疲劳分析CHK是否检查比例加载DM#多轴疲劳分析方法，Goodman、Findly(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATPARMIDTYPEMAXLFATSTRESSCOMBINECORRECTSTREPLA

30、STICSURFSTSRAINFLOWRTYPEGATERELPRPLDCHKMDMGMDLDM1DM2DM3CERYSURVCERTFOSFOSTYPE低周疲劳之单轴疲劳 2017 Altair Engineering, Inc. Proprietary and.s.应变疲劳应变疲劳主要用于低周疲劳(=1，构件可经历无限，否则不能经历无限78OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.FOS分析卡片设置MATFAT(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)M

31、ATFATMIDUNITSICYSUTSFOSTFLHSSSTHETASSHEAR79OptiStruct Fatigueysis, Ver2017TFL实数为扭转疲劳极限，整数为TFL VS HSS曲线HSS静水压力敏感系数STHETA安全角SSHEAR临界剪应力 2017 Altair Engineering, Inc. Proprietary and.s.FOS分析卡片设置FATPARM80OptiStruct Fatigueysis, Ver2017FOSTYPEFOS分析方法，Dang Van(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATPARMIDTYPEMA

32、XLFATSTRESSCOMBINECORRECTSTREPLASTICSURFSTSRAINFLOWRTYPEGATERELPRPLDCHKMDMGMDLDM1DM2DM3CERYSURVCERTFOSFOSTYPE焊缝疲劳 2017 Altair Engineering, Inc. Proprietary and.s.焊缝术语焊趾、焊喉、焊根、焊脚8282OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝应力特点焊趾位置存在应力集中，应力会随网格尺寸发生变化，不能直接采用FEM

33、应力评估焊缝疲劳力对网格尺寸不太敏感83OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝建模焊缝需用CQUAD4单元，尽量少用CTRIA3单元焊接单元的厚度为焊缝的厚度焊缝单元尽量规则，焊缝尺寸10mm左右焊缝单元的法向需指向外，而不是指向焊根。84OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝建模85OptiStruct Fatigueysis, Ver2017

34、 2017 Altair Engineering, Inc. Proprietary and.s.焊缝建模86OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳评估位置FilletOverlapLaser edge overlapLaser overlap87OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳SN曲线焊缝疲劳SN曲线由两条组成弯曲应力控制下的SN

35、曲线薄膜应力控制下的SN曲线88OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳评估方法单元1、2、3为评估位置，以评估单元2的损伤为例1.提取单元1、2、3焊线上节点力及力矩2.按单元权重分配节点力、弯矩89OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳评估方法3.由节点力计算R点、Q点线载荷值4.由R、Q点线载荷值计算中点位置线载荷值薄膜应力弯曲应力5

36、.由线载荷计算中心点应力90OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳评估方法6.计算弯曲率7.计算内插因子IFIF=0ifif根据内插因子IF修正SN曲线根据应力幅查SN曲线，得每个循环的疲劳，累计所有疲劳损伤得整个载荷历史的疲劳91OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳影响厚度修正焊缝的SN曲线是在指定厚度下得到的曲线疲劳分析对象是任意厚

37、度需根据分析对象厚度修正应力TREF_N、TREF为材料参数。92OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳影响FKMMSS平均应力修正Haigh diagram被分为4个区域1、4区域不需要修正区域2：区域3：其中M为平均应力敏感系数93OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳卡片设置FATSEAMSUBCASEFATDEFFATPARMFA

38、TSEQFATSEAMFATEVNTPFATSMWFOADMATFATTABFAT94OptiStruct Fatigueysis, Ver2017WTYPE焊缝类型(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATSEA MIDWTYPE2.7PS1 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳卡片设置PFATSMWSUBCASEFATDEFFATPARMFATSEQFATSEAMFATEVNTPFATSMWFOADMATFATTABFAT95OptiStruct Fatigueysis, Ver2017BRATI

39、O弯曲比TREF参考厚度TREF_N厚度影响指数(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)PFATSMWIDBRATIOTREFTREF_N 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳卡片设置FATPARMSUBCASEFATDEFFATPARMFATSEQFATSEAMFATEVNTPFATSMWFOADMATFATTABFAT96OptiStruct Fatigueysis, Ver2017METHOD焊缝分析方法，默认VOLVOCORRECT平均应力修正SURVCERT生存率THCKCOR R厚度修正(1)

40、(2)(3)(4)(5)(6)(7)(8)(9)(10)FATPARMIDTYPEMAXLFATSMWLDMETHODCORRECTSURVCERTTHCKCORR 2017 Altair Engineering, Inc. Proprietary and.s.焊缝疲劳卡片设置MATFAT97OptiStruct Fatigueysis, Ver2017FKMMSS_SM平均应力敏感系数A/R基于应力litude或应力range建立的SN曲线SR1_SMi疲劳强度系数B1_SMi疲劳强度指数NC1_SMi1段SN疲劳极限，2段SN转换循环B2_SMi2段SN疲劳强度指数FL_SMi疲劳极限(1

41、)(2)(3)(4)(5)(6)(7)(8)(9)(10)MATFATMIDUNITSMWLDFKMMSSSMA/RSR1_SM1B1_SM1NC1_SM1B2_SM1FL_SM1SE_SM1SR1_SM2B1_SM2NC1_SM2B2_SM2FL_SM2SE_SM2焊点疲劳 2017 Altair Engineering, Inc. Proprietary and.s.焊点建模焊点可采用CWELD、CBAR、CBEAM或CHEXA+RBE3焊点的长度为两块板的厚度和的一半被连接板需采用壳单元9999OptiStruct Fatigueysis, Ver2017 2017 Altair Eng

42、ineering, Inc. Proprietary and.s.焊点疲劳评估位置实验表明焊点破坏发生在三个位置焊核发生破坏被连接板件与焊核连接处发生破坏100OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊点疲劳评估方法焊点疲劳破坏应力板件连接处由应力控制焊核由最大主应力控制sheet对各个位置的破坏应力雨流计数，采用SN方法计算nugget最小为该焊点的寿命sheet101OptiStruct Fatigueysis, Ver2017采用临界平面法计算外径不同位置处破坏应力 2

43、017 Altair Engineering, Inc. Proprietary and.s.破坏应力计算板件连接处破坏沿每隔某个角度（默认18度，可自定义）计算径向应力102OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.破坏应力计算焊核处破坏沿每隔某个角度（默认18度，可自定义）计算正应力及剪应力103OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊点直径CWELD、

44、CBAR、CBEAM焊点直径由用户直接指定CHEXA单元焊点直径可由用户指定，也可为吸附面上中心点至各个边最小距离的两倍104OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.平均应力的影响FKM平均应力修正S0：修正后的应力幅S：应力幅Sm：平均应力M ：平均应力敏感系数105OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.厚度修正焊缝的SN曲线是在指定厚度下得到的曲线疲劳

45、分析对象是任意厚度需根据分析对象厚度修正应力TREF_N、TREF为材料参数。106OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.焊点疲劳卡片设置PFATSPWSUBCASEFATDEFFATPARMFATSEQPTYPEFATEVNTPFATSPWFOADMATFATTABFAT107OptiStruct Fatigueysis, Ver2017SPTFAIL损伤评估位置，焊核、板件连接处或全部HEXA_DHexa单元等效直径，可直接指定，也可自动计算TREF参考厚度TREF_N

46、厚度影响指数SF应力修正系数(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)PFATSPWIDSPTFAILALPHAHEXA_DTREFTREF_NSF 2017 Altair Engineering, Inc. Proprietary and.s.焊点疲劳卡片设置MATFAT共3条SN曲线，板1、板2、焊核与CBAR、CBEAM、CWELD上a点连接的壳单元为板1，另一边为板2与CHEXA低ID近的板为板1，另一边为板2108OptiStruct Fatigueysis, Ver2017FKMMSS_SP平均应力敏感系数SR1_Spi疲劳强度系数B1_Spi疲劳强度指数NC1

47、_SP1段的转折点B2_SP1段的疲劳强度指数FL_SP1疲劳极限(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)MATFATMIDUNITSPWLDFKMMSSSPSR1_SP1B1_SP1NC1_SP1B2_SP1FL_SP1SE_SP1 2017 Altair Engineering, Inc. Proprietary and.s.焊点疲劳卡片设置FATPARMSUBCASEFATDEFFATPARMFATSEQPTYPEFATEVNTPFATSPWFOADMATFATTABF109OptiStruct Fatigueysis, Ver2017METHOD焊点疲劳分析方法，

48、当前只支持RUPPCORRECT平均应力修SURVCERT存活率THCKCORR厚度修NANGLE沿评估的位置数，默认20个点，角度间隔为360/20=18度正正(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATPARMIDTYPEMAXLFATSPWLDMETHODCORRECTSURVCERTTHCKCORRNANGLE 2017 Altair Engineering, Inc. Proprietary and.s.焊点疲劳卡片设置如果采用CWELD模拟焊点，需在PWELD卡片上作类型设置(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)PWELDMIDDMS

49、ETTYPEDTABTID110OptiStruct Fatigueysis, Ver2017TYPE连接类型，如果是为了作疲劳分析， L=(t1+t2)/2，否则为单元实际长度随机振动疲劳 2017 Altair Engineering, Inc. Proprietary and.s.PSD随机振动分析流程1.通过随机振动分析得到应力PSD功率谱密度曲线由应力PSD曲线构造应力幅值概率密度PDF曲线由峰值穿越数得到所有应力幅的总循环数由概率密度函数及总循环数得到任意应力幅循环数由应力幅及循环数带入SN曲线求损伤累积不同应力幅下的损伤得到总损伤2.3.总循环数PDF4.5.6.任意应力幅的循环

50、数损伤累积111212OptiStruct Fatigueysis, Ver2017 2017 Altair Engineering, Inc. Proprietary and.s.OptiStruct 随机振动疲劳功能支持4种随机振动疲劳方法，主要体现在构造的PDF不同Dirlik Lalanne Narrow bandSteinbergs 3 band支持平均应力修正只支持基于Mises应力及第一主应力的评价方法支持壳体、实体单元单轴疲劳、焊点、焊缝疲劳结果输出为损伤及，默认时间为秒113OptiStruct Fatigueysis, Ver2017 2017 Altair Enginee

51、ring, Inc. Proprietary and.s.FATPARMSUBCASEFATDEFFATPARMFATSEQPFATFATEVNTMATFATFOADTABFATSREND114RDMGMDL随机振动字段标识DMi损伤模型：Dirlik，Lalanne，NB，3 brand，可指定多个损伤模型，最大损伤为最终结果RANDOM随机振动字段标识FACSREND基于RMS应力幅值的上限系数(SREND = 2*RMS Stress*FACSREND)SREND应力幅值上限(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATPARMIDTYPEMAXLFATSTRESS

52、COMBINECORRECTSTREPLASTICSURFSTSFOSFOSTYPERDMGMDLDM1DM2DM3RANDOMFACSRENDSRENDNBINDSTEXPSTSUBIDCopyright 2015 Altair Engineering, Inc. Proprietary ands 2017 Altair Engineering, Inc. Proprietary and.s.FATPARMSUBCASEFATDEFFATPARMFATSEQPFATFATEVNTMATFATFOADTABFAT115OptiStruct Fatigueysis, Ver2017DSNBIN在

53、0应力幅值上限范围内切分NBIN段，在每一段上计算概率。DS计算应力幅值概率时的应力幅值宽度STSUBID静力工况，考虑平均应力的影响(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATPARMIDTYPEMAXLFATSTRESSCOMBINECORRECTSTREPLASTICSURFSTSFOSFOSTYPERDMGMDLDM1DM2DM3RANDOMFACSRENDSRENDNBINDSSTSUBIDCopyright 2015 Altair Engineering, Inc. Proprietary ands 2017 Altair Engineering, Inc. Proprietary and.s.FATSEQSUBCASEFATDEFFATPARMFATSEQPFATFATEVNTMATFATFOADTABFAT116OptiStruct Fatigueysis, Ver2017FID1FATEVNT IDT1随机振动疲劳分析时间，为秒(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)FATSEQIDFID1T1Copyright 2015 Altair Engineering, Inc. Proprietary ands 2017 Altair Engineering, Inc. Propri