密质骨多级微结构的强韧机理

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1、重庆大学硕士学位论文单元-骨间质-黏合线三相裂纹扩展模型，应用扩展有限元方法，分别计算了不同模型中的应力应变，分析了黏合线对密质骨微裂纹扩展路径的影响。结果显示密质骨中的黏合线提高了微裂纹扩展的起始作用应变，也使得微裂纹折拐和偏转，这提高了骨的抗断裂能力。也基于Abaqus建立包含多个骨单元的三种裂纹扩展模型：密质骨单相模型、骨单元-骨间质两相模型以及骨单元-骨间质-黏合线三相模型。应用扩展有限元方法，分别计算了这三种不同模型中的应力应变，模拟了模型中的裂纹扩展。研究表明密质骨中的骨单元和黏合线提高了微裂纹扩展的起始作用应力及应变，使骨的刚度软化推迟、裂纹扩展速度减慢及

2、裂纹长度增加，从而提高了密质骨抵抗断裂的能力。⑤进行了密质骨仿生试件的制备。该试件反映了密质骨两级微结构的主要结构特征。对得到的仿生试件进行了力学行为的比较测试，得到的实验结果显示仿生螺旋纤维管复合材料试件具有较非螺旋纤维管复合材料试件更高的刚度、强度及韧性。关键词：密质骨，多级微结构，微裂纹，应力强度因子，仿生制备II英文摘要ABSTRACTAsakindofnaturalbiologicalcompositematerial,corticalboneconsistsofmineralizedcollagenfibers,hydroxyapatiteandothera

3、morphouscollagenmatters.Itpossesseshighstrength,stiffnessandfracturetoughness.Theexcellentmechanicalpropertiesofcorticalbonearecloselyrelatedtoitshierarchicalmicrostructure.Theinvestigationontherelationshipbetweenthehierarchicalmicrostructureandtheexcellentmechanicalpropertiescanrevealth

4、emechanismofstrengthandtoughnessofthebone,andprovideusefulguidanceforthedevelopmentofhigh-performancebiomimeticcomposites.Thisthesisinvestigatesthemechanismofstrengthandtoughnessofcorticalbonethroughexperimentalobservation,modelanalysis,numericalcalculation,biomimeticfabricationandexperi

5、mentalverification.Followingworksareaccomplishedandprofitableconclusionsareobtained.①Themicrostructureofcorticalboneisobservedwithscanningelectronmicroscope.Itisfoundedthatcorticalbonepossesseshierarchicalmicrostructure.Corticalboneisfirstcomposedofosteonsandinterstitialmatrix,andthenthe

6、osteonconsistsoflongandthincollagenfiberswhichhelicallyroundHaversiancanalattheircenter.Thereisaclearcementlineboundarybetweentheosteonandinterstitialmatrix.Itisalsoobservedthattheosteonsarepulledoutformtheinterstitialmatrixandthefibersarepulledoutfromtheosteons.②Theworkoffractureoftheos

7、teonsisanalyzedbasedonthetheoryoffiber-reinforcedcompositemesomechanics.It’sindicatedthatdebonding,slidingandpullingoutoftheosteonsbringmoreenergydissipationwhenthebonefracturesalongitscrosssectionandincreasethecapabilityresistingfractureofthebone.Basedonshearlagmodel,the