本文主要研究内容
作者张峰（2019）在《AZ31镁合金动态压缩变形机制与数值模拟》一文中研究指出：在航空航天、汽车工业和3C产品领域中镁合金的应用形式正在呈现出多样化和复杂化,因此,对镁合金的性能要求也由静态和准静态向动态转变。静态或准静态条件下镁合金的变形机制与动态变形条件下具有较大差异,动态变形条件下镁合金变形过程中会受到形变热的影响而表现出不同的物理状态。目前AZ31镁合金主要的应用形式是铸造态和变形态,然而其动态变形机制研究还不够系统,而且没有一种修正Johnson-Cook材料本构关系能够同时准确反映AZ31镁合金铸造态和变形态的动态变形行为,尤其是绝热剪切行为。因此本文以铸造态和具有较强{0002}织构的轧制态AZ31镁合金为研究对象,系统的研究AZ31镁合金动态力学性能及变形机制,通过修正Johnson-Cook材料本构模型的温度项,建立一个基于AZ31镁合金变形机制,并且能够准确反映材料真实变形过程的本构模型,其中包括铸态和变形态AZ31镁合金。通过编写key文件的方式将修正Johnson-Cook材料本构模型和累积损伤模型嵌入Lsdyna软件中,对AZ31镁合金的动态变形过程进行数值仿真,特别是其绝热剪切过程。设计新型承压环装置捕捉实际实验条件下AZ31镁合金绝热剪切行为组织演变过程,验证修正Johnson-Cook材料本构模型和累积损伤模型的正确性,同时分析讨论AZ31镁合金绝热剪切变形机理。本研究利用分离式霍普金森压杆系统结合电阻式加热炉装置,分别对AZ31镁合金轧制态的ND（normal direction）、TD（transverse direction）、RD（rolling direction）以及铸态试样进行了温度范围为20-350℃,应变率范围为0.001-2200s-1的冲击试验。结合光学显微镜（OM）和电子背散射衍射技术（EBSD）观察了不同条件下试样的微观组织,揭示了动态载荷下AZ31镁合金的变形行为、组织演变过程、动态变形与失效的机理。本研究发现,室温条件下铸态与轧制态AZ31镁合金柱状试样压缩真实应力-应变关系曲线可划分为4个阶段:弹性变形阶段、塑性变形应变硬化阶段、塑性变形热软化作用增强阶段和卸载回复或失效断裂阶段。相同应变速率AZ31镁合金的压缩真实应力-应变曲线的峰值应力随着温度的升高而降低,应变最大值随着温度的升高而增加;温度对轧制态AZ31镁合金的各向异性具有减弱作用,而应变率对轧制态AZ31镁合金的各向异性具有强化作用;轧制态AZ31镁合金随着应变率的提高孪晶逐渐向晶界区域靠近形成大量的位错塞积,当位错塞积累积到一定程度,产生裂纹。轧制态AZ31镁合金帽状试样的动态再结晶机制是由温度、初始晶体取向和载荷方向共同决定的。AZ31-ND的绝热剪切带是由大量的动态再结晶形成的等轴晶组织、少量的亚结构和变形晶粒所组成,其绝热剪切带两侧基体中的{10-12}拉伸孪晶和{10-11}压缩孪晶均为长针状。基于斯密特因子判断其变形机制启动由难到易的顺序为:{10-12}拉伸孪晶,{10-11}压缩孪晶,柱面滑移,锥面<a>滑移,基面滑移,锥面<c+a>滑移。AZ31-TD的绝热剪切带是由少量的动态再结形成的等轴晶组织、大量的亚结构和变形晶粒所组成,其绝热剪切带两侧基体中的{10-12}拉伸孪晶和{10-11}压缩孪晶均为短针状。基于斯密特因子判断其变形机制启动由难到易的顺序为:{10-11}压缩孪晶,柱面滑移,基面滑移,锥面<c+a>滑移,锥面<a>滑移,{10-12}拉伸孪晶。针对Johnson-Cook本构模型的不足,基于镁合金形变热和环境温度对温度软化项进行了修正,将环境温度以函数形式设定为修正后本构模型的热软化系数,并且根据AZ31镁合金压缩真实应力应变数据,通过最小二乘法拟合出铸态和轧制态AZ31镁合金的修正Johnson-Cook本构模型及损伤模型的实常数。通过动态压缩应力应变曲线数据与修正Johnson-Cook本构模型的理论计算数据对比,验证了修正后Johnson-Cook本构模型的准确性,并建立了修正后的铸态、轧制态AZ31镁合金本构模型和损伤模型。通过对理论计算和实测结果的对比,发现修正后的Johnson-Cook模型能够较为准确地反映合金变形过程,只是发生{10-12}拉伸孪生时,理论计算和实测结果之间稍有误差。基于修正后的Johnson-Cook本构模型和损伤模型,应用LS-DYNA软件对轧制态AZ31镁合金帽状试样动态压缩应力状态进行了仿真,给出了绝热剪切变形过程中再结晶和失效的临界值,揭示了外载荷作用初期帽状试样拐角处“耳状”塑性增强区的形成,以及向两拐点连线区域中间的扩展过程,随着外载荷增加其上下端被压制,以及在动态载荷作用下,材料内部塑性功转变为热使材料的温度升高,形成绝热剪切组织。对帽状试样失效过程的模拟仿真显示,当应力累积到一定程度时,帽状试样两拐角处产生裂纹,裂纹的出现使得应力得到了一定程度的释放。随着载荷的持续增加裂纹逐渐由拐角向中间扩展,导致失效。
Abstract
zai hang kong hang tian 、qi che gong ye he 3Cchan pin ling yu zhong mei ge jin de ying yong xing shi zheng zai cheng xian chu duo yang hua he fu za hua ,yin ci ,dui mei ge jin de xing neng yao qiu ye you jing tai he zhun jing tai xiang dong tai zhuai bian 。jing tai huo zhun jing tai tiao jian xia mei ge jin de bian xing ji zhi yu dong tai bian xing tiao jian xia ju you jiao da cha yi ,dong tai bian xing tiao jian xia mei ge jin bian xing guo cheng zhong hui shou dao xing bian re de ying xiang er biao xian chu bu tong de wu li zhuang tai 。mu qian AZ31mei ge jin zhu yao de ying yong xing shi shi zhu zao tai he bian xing tai ,ran er ji dong tai bian xing ji zhi yan jiu hai bu gou ji tong ,er ju mei you yi chong xiu zheng Johnson-Cookcai liao ben gou guan ji neng gou tong shi zhun que fan ying AZ31mei ge jin zhu zao tai he bian xing tai de dong tai bian xing hang wei ,you ji shi jue re jian qie hang wei 。yin ci ben wen yi zhu zao tai he ju you jiao jiang {0002}zhi gou de ga zhi tai AZ31mei ge jin wei yan jiu dui xiang ,ji tong de yan jiu AZ31mei ge jin dong tai li xue xing neng ji bian xing ji zhi ,tong guo xiu zheng Johnson-Cookcai liao ben gou mo xing de wen du xiang ,jian li yi ge ji yu AZ31mei ge jin bian xing ji zhi ,bing ju neng gou zhun que fan ying cai liao zhen shi bian xing guo cheng de ben gou mo xing ,ji zhong bao gua zhu tai he bian xing tai AZ31mei ge jin 。tong guo bian xie keywen jian de fang shi jiang xiu zheng Johnson-Cookcai liao ben gou mo xing he lei ji sun shang mo xing qian ru Lsdynaruan jian zhong ,dui AZ31mei ge jin de dong tai bian xing guo cheng jin hang shu zhi fang zhen ,te bie shi ji jue re jian qie guo cheng 。she ji xin xing cheng ya huan zhuang zhi bu zhuo shi ji shi yan tiao jian xia AZ31mei ge jin jue re jian qie hang wei zu zhi yan bian guo cheng ,yan zheng xiu zheng Johnson-Cookcai liao ben gou mo xing he lei ji sun shang mo xing de zheng que xing ,tong shi fen xi tao lun AZ31mei ge jin jue re jian qie bian xing ji li 。ben yan jiu li yong fen li shi huo pu jin sen ya gan ji tong jie ge dian zu shi jia re lu zhuang zhi ,fen bie dui AZ31mei ge jin ga zhi tai de ND（normal direction）、TD（transverse direction）、RD（rolling direction）yi ji zhu tai shi yang jin hang le wen du fan wei wei 20-350℃,ying bian lv fan wei wei 0.001-2200s-1de chong ji shi yan 。jie ge guang xue xian wei jing （OM）he dian zi bei san she yan she ji shu （EBSD）guan cha le bu tong tiao jian xia shi yang de wei guan zu zhi ,jie shi le dong tai zai he xia AZ31mei ge jin de bian xing hang wei 、zu zhi yan bian guo cheng 、dong tai bian xing yu shi xiao de ji li 。ben yan jiu fa xian ,shi wen tiao jian xia zhu tai yu ga zhi tai AZ31mei ge jin zhu zhuang shi yang ya su zhen shi ying li -ying bian guan ji qu xian ke hua fen wei 4ge jie duan :dan xing bian xing jie duan 、su xing bian xing ying bian ying hua jie duan 、su xing bian xing re ruan hua zuo yong zeng jiang jie duan he xie zai hui fu huo shi xiao duan lie jie duan 。xiang tong ying bian su lv AZ31mei ge jin de ya su zhen shi ying li -ying bian qu xian de feng zhi ying li sui zhao wen du de sheng gao er jiang di ,ying bian zui da zhi sui zhao wen du de sheng gao er zeng jia ;wen du dui ga zhi tai AZ31mei ge jin de ge xiang yi xing ju you jian ruo zuo yong ,er ying bian lv dui ga zhi tai AZ31mei ge jin de ge xiang yi xing ju you jiang hua zuo yong ;ga zhi tai AZ31mei ge jin sui zhao ying bian lv de di gao luan jing zhu jian xiang jing jie ou yu kao jin xing cheng da liang de wei cuo sai ji ,dang wei cuo sai ji lei ji dao yi ding cheng du ,chan sheng lie wen 。ga zhi tai AZ31mei ge jin mao zhuang shi yang de dong tai zai jie jing ji zhi shi you wen du 、chu shi jing ti qu xiang he zai he fang xiang gong tong jue ding de 。AZ31-NDde jue re jian qie dai shi you da liang de dong tai zai jie jing xing cheng de deng zhou jing zu zhi 、shao liang de ya jie gou he bian xing jing li suo zu cheng ,ji jue re jian qie dai liang ce ji ti zhong de {10-12}la shen luan jing he {10-11}ya su luan jing jun wei chang zhen zhuang 。ji yu si mi te yin zi pan duan ji bian xing ji zhi qi dong you nan dao yi de shun xu wei :{10-12}la shen luan jing ,{10-11}ya su luan jing ,zhu mian hua yi ,zhui mian <a>hua yi ,ji mian hua yi ,zhui mian <c+a>hua yi 。AZ31-TDde jue re jian qie dai shi you shao liang de dong tai zai jie xing cheng de deng zhou jing zu zhi 、da liang de ya jie gou he bian xing jing li suo zu cheng ,ji jue re jian qie dai liang ce ji ti zhong de {10-12}la shen luan jing he {10-11}ya su luan jing jun wei duan zhen zhuang 。ji yu si mi te yin zi pan duan ji bian xing ji zhi qi dong you nan dao yi de shun xu wei :{10-11}ya su luan jing ,zhu mian hua yi ,ji mian hua yi ,zhui mian <c+a>hua yi ,zhui mian <a>hua yi ,{10-12}la shen luan jing 。zhen dui Johnson-Cookben gou mo xing de bu zu ,ji yu mei ge jin xing bian re he huan jing wen du dui wen du ruan hua xiang jin hang le xiu zheng ,jiang huan jing wen du yi han shu xing shi she ding wei xiu zheng hou ben gou mo xing de re ruan hua ji shu ,bing ju gen ju AZ31mei ge jin ya su zhen shi ying li ying bian shu ju ,tong guo zui xiao er cheng fa ni ge chu zhu tai he ga zhi tai AZ31mei ge jin de xiu zheng Johnson-Cookben gou mo xing ji sun shang mo xing de shi chang shu 。tong guo dong tai ya su ying li ying bian qu xian shu ju yu xiu zheng Johnson-Cookben gou mo xing de li lun ji suan shu ju dui bi ,yan zheng le xiu zheng hou Johnson-Cookben gou mo xing de zhun que xing ,bing jian li le xiu zheng hou de zhu tai 、ga zhi tai AZ31mei ge jin ben gou mo xing he sun shang mo xing 。tong guo dui li lun ji suan he shi ce jie guo de dui bi ,fa xian xiu zheng hou de Johnson-Cookmo xing neng gou jiao wei zhun que de fan ying ge jin bian xing guo cheng ,zhi shi fa sheng {10-12}la shen luan sheng shi ,li lun ji suan he shi ce jie guo zhi jian shao you wu cha 。ji yu xiu zheng hou de Johnson-Cookben gou mo xing he sun shang mo xing ,ying yong LS-DYNAruan jian dui ga zhi tai AZ31mei ge jin mao zhuang shi yang dong tai ya su ying li zhuang tai jin hang le fang zhen ,gei chu le jue re jian qie bian xing guo cheng zhong zai jie jing he shi xiao de lin jie zhi ,jie shi le wai zai he zuo yong chu ji mao zhuang shi yang guai jiao chu “er zhuang ”su xing zeng jiang ou de xing cheng ,yi ji xiang liang guai dian lian xian ou yu zhong jian de kuo zhan guo cheng ,sui zhao wai zai he zeng jia ji shang xia duan bei ya zhi ,yi ji zai dong tai zai he zuo yong xia ,cai liao nei bu su xing gong zhuai bian wei re shi cai liao de wen du sheng gao ,xing cheng jue re jian qie zu zhi 。dui mao zhuang shi yang shi xiao guo cheng de mo ni fang zhen xian shi ,dang ying li lei ji dao yi ding cheng du shi ,mao zhuang shi yang liang guai jiao chu chan sheng lie wen ,lie wen de chu xian shi de ying li de dao le yi ding cheng du de shi fang 。sui zhao zai he de chi xu zeng jia lie wen zhu jian you guai jiao xiang zhong jian kuo zhan ,dao zhi shi xiao 。
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论文作者分别是来自沈阳工业大学的张峰，发表于刊物沈阳工业大学2019-07-11论文，是一篇关于镁合金论文,动态压缩论文,本构方程论文,有限元论文,绝热剪切论文,沈阳工业大学2019-07-11论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自沈阳工业大学2019-07-11论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。
标签：镁合金论文; 动态压缩论文; 本构方程论文; 有限元论文; 绝热剪切论文; 沈阳工业大学2019-07-11论文;