含缺陷蜂窝夹层板的弯曲力学性能分析

硕士学位论文含缺陷蜂窝夹层板的弯曲力学性能分析ANALYSISOFBENDINGMECHANICALPROPERTIESOFHONEYCOMBSANDWICHSTRUCTUREWITHDEFECTS尉坤哈尔滨工业大学2012年7月国内图书分类号：学校代码：10213UDC：密级：公开工学硕士学位论文含缺陷蜂窝夹层板的弯曲力学性能分析硕士研究生：尉坤导师：韩杰才教授申请学位：工学硕士学科：工程力学所在单位：航天学院答辩日期：2012年7月授予学位单位：哈尔滨工业大学ClassifiedIndex:U.D.C:DissertationfortheMasterDegreeinEngineeringANALYSISOFBENDINGMECHANICALPROPERTIESOFHONEYCOMBSANDWICHSTRUCTUREWITHDEFECTSCandidateCandidateCandidateCandidate：：：：YuKunSupervisorSupervisorSupervisorSupervisor：：：：Prof.HanJiecaiAcademicAcademicAcademicAcademicDegreeDegreeDegreeDegreeAppliedAppliedAppliedAppliedforforforfor：：：：MasterofEngineeringSpecialitySpecialitySpecialitySpeciality：：：：EngineeringMechanicsAffiliationAffiliationAffiliationAffiliation：：：：SchoolofAstronauticsDateDateDateDateofofofofDefenceDefenceDefenceDefence：：：：July,2012Degree-Conferring-InstitutionDegree-Conferring-InstitutionDegree-Conferring-InstitutionDegree-Conferring-Institution：：：：HarbinInstituteofTechnology哈尔滨工业大学工学硕士学位论文-I-摘要近年来金属蜂窝夹芯结构由于其诸多优点，广泛应用于航空航天领域，而由于工艺原因金属蜂窝结构不可避免的含有一些工艺缺陷。有些缺陷对其使用性能没有影响，而有些缺陷的存在却严重影响着其使用的安全性，所以本文针对严重影响蜂窝板力学性能的面芯脱焊缺陷进行分析。又因为蜂窝板在结构中作为外部面板主要承受弯曲载荷，所以本文针对蜂窝夹芯结构的弯曲性能进行分析。首先，采用有限元法计算蜂窝夹芯结构的等效刚度矩阵。本文利用蜂窝夹芯结构的一个单胞进行建模，理论上推导出单胞建模所需要施加周期位移边界条件，在整个计算过程中考虑了蜂窝夹芯结构的内部结构，而且单胞计算大大减少了整个刚度矩阵的计算时间，对比计算结果发现面芯脱焊对蜂窝夹芯结构的弯曲性能影响比较大。然后，采用三点弯曲试验对含缺陷蜂窝夹芯结构的弯曲性能进行分析。在试验中设计两种缺陷尺寸，实验试件又分为长梁，短梁，薄蒙皮梁和厚蒙皮梁。在进行弯曲实验之前先通过红外热波和超声波的方法对蜂窝夹芯结构进行了无损检测，验证了蜂窝夹芯结构所含缺陷是本文所设计尺寸，然后通过短梁测定蜂窝夹芯结构的剪切强度，通过长梁测得蜂窝夹芯结构的弯曲拉压强度，通过外伸梁实验测定蜂窝夹芯结构的弹性模量和蜂窝芯子的剪切模量。最后，通过数值模拟对在不同条件下含各种缺陷的蜂窝夹芯结构弯曲性能进行分析。利用数值方法对试验中采用的含缺陷蜂窝夹芯板的弯曲性能进行模拟分析，并且与试验结果进行比较，验证了数值分析模型的正确性。分别在室温和高温下对不同面板厚度的蜂窝夹芯结构进行弯曲性能模拟，结果表明在常温和高温条件下当面板厚度增加而蜂窝芯子壁厚度不变时弯曲性能受缺陷影响程度随着蜂窝面板厚度增加减弱。本文还分别对在上面板与芯子之间和下面板与蜂窝芯子之间脱焊两种情况进行模拟，发现无论缺陷在上面板还是在下面板，当缺陷的尺寸达到一定值时刚加载试件马上就完全屈服破坏。关键词：缺陷；蜂窝夹芯结构；力学性能；三点弯曲试验；数值模拟哈尔滨工业大学工学硕士学位论文-II-AbstractRecently,metalhoneycombsandwichstructuresarewidelyusedinaerospacefieldbecauseofitsspecificadvantages.However,therearesomeinevitabletechnicaldefectsinthemetalcellularstructure.Somedefectswon’taffectthemechanicalperformance,butsomeareseriouslyharmfultothesafetyinuse.Basedontheproblem,surfaceandhoneycombde-solderingdefectswhichwillseriouslyaffectmechanicalpropertiesofhoneycombsandwichstructureareanalyzedinthispaper.Becausethehoneycombsandwichstructureisusuallyusedtobearthebendingloadasexternalpanel,thebendingperformanceisalsodiscussedinthispaper.Firstofall,theFEMisusedtocalculateequivalentstiffnessmatrixofthehoneycombsandwichstructure.Asingleunitmodelofthestructureisbuilt,andperiodicdisplacementboundaryconditionsofsingleunitmodelingarederivedtheoretically.Inthewholecalculation,theinternalstructureistakenintoaccount.Theusageofsingleunittoobtainthewholestiffnessmatrixcansavethecomputationtimeenormously.Theresultdemonstratesthatsurfaceandhoneycombde-solderingdefectscaninfluencethebendingperformanceofthestructuregreatly.Then,threepointbendingtestisperformedtoanalyzebendingperformanceofthehoneycombsandwichstructurewithdefects.Inthetest,twodefectdimensionsaredesigned,differenttestpiecesarechosen,whicharethelongandshortbeams,thickandthincoveringbeams.NDTisconductedbeforebendingtestwithinfraredandsupersonicmethodtomakesurespecimenswiththedesigndefects.Shortbeamexperimentisusedtodetermineshearstrength(modulus)ofthestructure.Longbeamexperimentisusedtoobtainthebendingstrength.Overhangingbeamtestisusedtomeasuretheelasticmodulusofthestructureandshearmodulusofthehoneycombcore.Finally,thebendingperformanceofhoneycombsandwichstructurewithdifferentdefectsundervariousconditionsisanalyzedbynumericalsimulation.Numericalmethodisusedtosimulateandanalyzethebendingperformanceofhoneycombcorestructurewithdefects,whichisalsoverifiedincomparisonwiththetestresults.Bendingtestofhoneycombstructureindifferentthicknessunderroomtemperatureandhightemperatureisconducted,respectively.Itisfoundthatwiththethicknessofsurfacepanel,thehoneycombcorethicknessremainsconstant.哈尔滨工业大学工学硕士学位论文-III-Therefore,itislessinfluenceonthebendingperformancebythedefects.Inaddition,twode-solderingconditionsaresimulated.Theresultsshowthatwhendefectsexistonupperorunderpanel,thespecimenwillbedestroyedquicklyifthedefectsdimensionreachesacertainvalue.KeywordsKeywordsKeywordsKeywords:defect,honeycombsandwichstructure,mechanicalproperty,three-pointbendingtest,numericalsimulation哈尔滨工业大学工学硕士学位论文-IV-目录摘要................................................................................................................................IAbstract.............................................................................................................................II第1111章绪论............................................................................................................-1-1.1课题背景...........................................................................................................-1-1.2国内外研究现状..............................................................................................-3-1.2.1蜂窝夹芯结构常见的缺陷类型..............................................................-3-1.2.2蜂窝夹芯结构的无损检测方法....................