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时间:2019-11-27
《轴向共振控制的结构疲劳裂纹扩展分析》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、第42卷第3期2010年6月南京航空航天大学学报JournalofNanjingUniversityofAeronautics&Astronautics轴向共振控制的结构疲劳裂纹扩展分析刘文光陈国平(南京航空航天大学飞行器结构力学与控制教育部重点实验室,南京,210016)V01.42No.3Jun.2010摘要:针对工程结构共振疲劳问题,提出一种激励频率跟踪随裂纹扩展变化的固有频率的加载方法,并对共振按带激励的裂纹悬臂杆进行理论分析。分析过程中,采用线性弹簧等效裂纹单元,复弹性模量考虑阻尼行为,得到考虑激励幅值、激励频率、阻尼以及裂纹长度等因素
2、的动应力。利用Paris方程模拟裂纹扩展过程,分析阻尼对共振结构疲劳裂纹扩展寿命的影响。结果显示:裂纹扩展使结构共振频率下降;阻尼较小时,阻尼变化对疲劳裂纹扩展寿命的影响并不显著;阻尼达到一定值后,裂纹扩展速率迅速下降,可能发生止裂现象;越低阶模态振动.裂纹扩展速率越大,对应的疲劳裂纹扩展寿命越短。关键词:振动疲劳;共振;阻尼;裂纹扩展中图分类号:V216.3;V224文献标识码:A文章编号:1005—2615(2010)03—0298—05FatigueCrackPropagationResonanceControllStructuresonL
3、ongitudinalVibrationLiuWenguang,ChenGuoping(MOEKeyLabofStructureMechanicsandControlforAircraft,NanjingUniversityofAeronautics&Astronautics.Nanjing,210016,China)Abstract:Accordingtotheresonancefatigueproblemoftheengineeringstructure,theloadingmethodforthenaturalfrequencyisprop
4、osed.Thefrequenciesarechangedwithcrackpropagationbytheexcita—tionfrequencybasedonthemodifiednaturalfrequencyequation,andthelawoffatiguecrackgrowthforthecrackedcantileverbeamunderthelongitudinalresonanceisstudied.Thecrackelementisreplacedbythelinearspringandthedampinglossfacto
5、risintroducedbycomplexelasticmodulusonvibrationstressanalysis.Sothattheloadingamplitudeandthecracklengthtogetherwiththeexcitationfrequencyanddampingareconsideredinthedynamicstress.TheParisequationisusedtosimulatethecrackprop.agationforanalyzingthefatiguelifeofthecantileverbea
6、m.Resultsindicatethatthepropagatingcrackintroducestheflexibilitytothecontinuoussystem,thusresultingingradualshiftingawayofthereso—nanceresultinsmallerloadingofthecrackedsection.Thisreduces,thegrowthratetobedroppedandbringseventuallythesystemtoacertainvalueofthecrackpropagatio
7、nratebelowaconventionalthresh—oldratewhichcanbeinterpretedasdynamiccrackarrest.Differentlawsofthecrackpropagationondif—ferentmodes,thusthecrackpropagationspeedonthelowmodeisfasterthanthatofthehighmodeandthatneedslesstimetospendforpropagatingcertaincracklength.Keywords:vibrati
8、onfatigue;resonance;damping;crackpropagation随着现代机械装备朝着高速、轻柔、大功率的方向发展
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