应力状态对金属材料损伤演化和断裂的影响

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1、摘要通过有限元计算，分析了平面应变和平面应力下的主应力比对长条形微孔洞损伤演化行为的影响。计算结果表明：三向应力度口相同时。不同的主应力比a扣．会引起不同的孔洞长大和聚合行为，从而使开裂路径和断裂时的应变不同。当仃／仃．>1时，最大主应力为仃：，由孔洞长大和聚合所决定的开裂路径倾向于垂直于叮，方向．当仃2，矾

2、。的影响。通过有限元计算，分析了平面应变下的主应力比对圆形微孔洞损伤演化行为的影响．计算结果表明：应力状态的变化对圆形孔洞损伤演化的影响弱于长条形孔洞．长条形孔洞长大和聚合容易发生在长径相互平行的大孔洞之间，孔洞长大存在明显的各向异性。同时，长条形孔洞长大的个体差异很悬殊，某些大孔洞主导了材料的最终断裂。而圆形孔洞的长大和聚合主要取决于孔洞的分布．另外，长条形孔洞的长大和聚合随应力状态变化范围要比圆形孔洞的大，圆形孔洞长大和聚合只有在主应力比相差十分悬殊的情况下才会发生变化。关键词：应力状态主应力比孔洞损伤演化断裂有限元平面应力平面应变ABSTRAcTTheeffectofprinc

3、ipalstressratioondilmageevolutionofstripvoidhasbeenanalyzedbyusingfiniteelementmethodinplanestrainandplanestress．Theresultsshowthatthevoidgrowthandcoalesc七ncebehavioriSdifferent砒variousprincipalstressratios仃，，仃，inthecaseofthe懿Imestresstriaxiality．TlliSc41Uflesdifferentcrackgrowthpathsandfractur

4、estrains．Whenthe口，，盯，islargerthenl，themaximumprincipalstressis口，，andthecrackgrowthpathdeterminedbythevoidgrowthandcoalescencetendstObeverticaltOthe盯，direction．Whencr_，／a．iSlessthenl，themaximumprincipalstressiS盯，，andthecrackgrowthpathdeterminedbythevoidgrowthandcoalescencetendstobeverticaltothed

5、r，direction．W曲incressingtheprincipalstressratiocr／a，，theincreaserateofthevoidareafraction扣withtheprincipalmainellincreases，andtheprincipalstrain(811)，atfracturedecreases．Therefore,whentheeffectofthestressstateonthedamageandfracturebehaviorofmatedalsisanalyzedandthemechanicalmodeliSestablished，n

6、otonlytheeffectofstresstriaxialityshouldbeconsidered,butalsotheprincipalstressratio．TheeffectofprincipalatressratioOffvoiddamageevolutionofroundvoidhasbeenanalyzedbyusingfhlitcelementmethodinplanestrain．11圮resultsshowthattheeffectofstressstateondamageevolutionofroundvoidstripvoidiSweakerthantha

7、tofstripvoid．thevoidgrowthandcoalescenceofthestripvoidispronetooccuringbetweenbigVOidsthattheirlongerdiametersaleparalleUing．growthisobviouslyanisotropic．Thediffierenc宅betweenvoidgrowthsforthestripvoidsislarge，andsomebigvoidsdetem