内聚力界面单元与复合材料的界面损伤分析VIP免费

力学学报990314力学学报ACTAMECHANICASINICA1999年第3期No.31999内聚力界面单元与复合材料的界面损伤分析1)周储伟杨卫方岱宁摘要推导了一种基于内聚力模型无厚的界面单元,用来模拟复合材料纤维与基体之间的界面层.研究了纤维周期分布的复合材料受横向荷载时,在界面不同的强韧性条件下其界面损伤演化的规律和对复合材料整体性质的影响.关键词复合材料力学,界面单元,内聚力模型,损伤COHESIVEINTERFACEELEMENTANDINTERFACIALDAMAGEANALYSISOFCOMPOSITES1)ZhouChuweiYangWeiFangDaining(DepartmentofEngineeringMechanics,TsinghuaUniversity,Beijing100084,China)AbstractAninterfaceelementbasedonthecohesivezonemodelisemployedtosimulatethefiber/matrixinterfaceincomposite.Thecohesivezonemodelusedhereisviewedasaphenomenologicalmodel.Apotentialfunctionisadoptedtodescribetherelationshipbetweentheinterfacetractionandtheinterfacedisplacementjump.Twosetsofinterfaceparametersareadoptedtorepresenttheinterfacestrengthandtoughnessrespectively.Thismodelcansimulatetheevolutionofinterfacedamages,whicharecoupledinthenormalandtangentialdirections.Theinterfaceelementhasnothicknessinitially.Thisinterfacedamagemodelisperformedtocompositeswhichhaveperiodicarrayoffibersandaresubjectedtoatransverseload.Forsymmetry,thecomputationalrepresentativeelement(RVE)containsaquarteroffiber.Thefiberisassumedaselasticmaterialanditsstiffnessismuchhigherthanthatofthematrixmaterial.Thematrixisassumedasisotropichardeningelastic-plasticmaterial.Finitedeformationisconsidered.Theinterfacedamageevolutionanditseffectonthepropertiesofcompositesundertheconditionsofvariousinterfacestrengthsandtoughnessisinvestigated.Theresultsshowthatthedebondingstartsatthepolarregionofthefiberandmovestotheequatorregionwiththeloadingincreasing.TheaveragetensilestressontheRVEdropswhenthedebondingtakesplace.Largeinterfacestrengthbringsonthedelayedinterfacedebondingandthehighultimatetensilestrength.Withthesameinterfacestrength,thehighinterfacetoughnessmeansthelowinterfacestiffnessandhighenergytoseparatetheinterface.Sothedebondinginitiationandfile:///E|/qk/lxxb/lxxb99/lxxb9903/990314.htm（第1／9页）2010-3-233:48:10万方数据力学学报990314evolutionareretardedincaseofthehighinterfacetoughness.Themaximumnormaldisplacementjumpisatthepolarregionofthefiberandthemaximumtangentdisplacementjumpisneartheregionofθ=π/4.Inshort,theinterfacestrengthandtoughnessarebeneficialtotheinterfacedebondingresistancecapacityandthestrengthofthecomposite.Keywordsmechanicsofcompositematerials,interfaceelement,cohesivezonemodel,damage引言复合材料中增强相与基体之间界面层的性质,对于复合材料整体刚度、强度、韧性等性能起着至关重要的作用.要研究复合材料的损伤破坏过程,需分析纤维或颗粒直径尺度上的应力应变场,有限元数值分析是有效的工具.由于复合材料的界面层往往很薄,远小于纤维直径,而且沿厚度方向性质是变化的［1］.这就给传统的有限元分析带来诸如单元剖分,材料参数的确定等困难.J.D.Achenbach［2］,陈陆平等［3］将界面层处理为类似于一组法向和切向正交的弹簧,叶碧泉等［4］用各向同性的无厚单元模拟界面层.这些工作解决了单元划分的厚度问题,但未能反映出界面损伤时法向和切向的耦合效应.本文利用内聚力模型推导了一种无厚的界面层单元,将界面层的性质直接反映在界面层的粘结力与界面层上下两个面的相对位移的关系上.1内聚力模型本文推导的界面单元是基于内聚力模型［5～7］.内聚力实质上是物质原子或分子之间的相互作用力,复合材料的界面是由基体和增强相通过化学反应生成的一层结构复杂的物质［1］.所以内聚力模型只是一种简化,但通过适当地选取参数,可以反映出界面层物质的模量、强...