6000系铝合金薄壁结构压缩断裂行为的有限元模拟

２０１６年７月第４０卷第７期 Vol．４０No．７Jul．２０１６

DOI :１０．１１９７３/j x g ccl２０１６０７０１７

收稿日期:２０１５-０６-０８;修订日期:２０１６-０５-２０基金项目:国家自然科学基金面上资助项目(５１４７５１５６);宁夏大学自然科学研究基金资助项目(ZR１４０３);宁夏大学人才引进科研启动基金资助项目(BQD２０１４０１８)

;湖南大学汽车车身先进设计制造国家重点实验室开放基金资助项目(３１５１５００７)作者简介:王冠(１９８５－),男,河南郑州人,讲师,博士.通讯作者:李落星教授６０００系铝合金薄壁结构压缩断裂行为的有限元模拟

王冠１,２,寇琳媛１,徐从昌２,叶拓２,李落星２

(１．宁夏大学机械工程学院,银川７５００２１;２．

湖南大学,汽车车身先进设计制造国家重点实验室,长沙４１００８２)摘 要:针对汽车用６０６１和６０６３铝合金薄壁结构,先进行了准静态拉伸试验和１８０?

弯曲试验,得到了铝合金的真应力-真应变曲线;然后采用线性回归拟合的方法建立了铝合金韧性断裂的本构模型,在此基础上,建立了铝合金薄壁结构压缩失效的有限元模型,并通过轴向压缩试验验证了有限元模型的准确性.结果表明:拉伸后,６０６１铝合金的表面呈橘皮形貌,６０６３铝合金的表面比较光滑;两种铝合金的断裂均为韧性断裂,６０６３铝合金具有更好的韧性;６０６１和６０６３铝合金的韧性断裂准则参数分别为１０４．８１MPa 和１７９．９１MPa ;

有限元预测得到的铝合金薄壁结构的失效行为与试验结果比较吻合,证明了铝合金韧性断裂本构模型的正确性.

关键词:铝合金;

薄壁结构;韧性断裂;本构模型中图分类号:TG１４６．２１ 文献标志码:A 文章编号:１０００-３７３８(２０１６)０７-００７３-０８Finite Element Modelin g for Com p ression Fracture Behavior of ６０００Aluminum Allo y s Thin-Walled Structure

WANG Guan １,２,KOU Lin-y uan １,XU Con g -chan g ２,YE Tuo ２,LI Luo-xin g ２

(１．Colle g e of Mechanical and Vehicle En g ineerin g ,Nin g xia Universit y ,Yinchuan ７５００２１,China ;２．State Ke y Laborator y of Advanced Desi g n and Manufacture for Vehicle Bod y ,Hunan Universit y ,Chan g sha ４１００８２,China )Abstract :Accordin g to the thin-walled structure of ６０６１and ６０６３aluminum allo y s ,the true stress-strain curve were obtained b y q uasi-static tensile test and １８０de g ree bendin g ex p eriment ,and then ,the constitutive model for ductile fracture was established b y linear re g ression fittin g ．On this basis ,com p ression failure finite element model for aluminum allo y thin-walled structure was built ,and the accurac y of the finite element model was verified b y axial com p ression test．The results show that the surface of ６０６１aluminum allo y was p eel mor p holo gy ,while the surface of ６０６３aluminum allo y was smooth ;the fracture modes of two kinds of aluminum allo y s were ductile fracture ;the tou g hness of ６０６３aluminum allo y was better than that of ６０６１aluminum allo y ;the p arameters of fracture model of ６０６１and ６０６３aluminum allo y s were １０４．８１MPa and １７９．９１MPa ;the failure behavior of aluminum allo y thin-walled structure obtained b y simulation and ex p eriment were in g ood a g reement ,which indicated that the ductile fracture constitutive model of aluminum allo y s was accurate．Ke y words :aluminum allo y ;thin-walled structure ;ductile fracture ;constitutive model

０ 引 言

目前,在汽车设计领域,通常以材料的极限塑性

应变作为其失效准则,该准则的参数求解比较简单,

但是精度较低.Keeler [１]和Goodwin [２]提出了集中性颈缩失稳准则,即:成形极限图(FLD ).但FLD 应用于薄壁结构变形时会有很多局限,尤其是对于

铝合金薄壁结构来说,它的断裂属于典型的韧性断

裂,随着变形的进行,它的成形极限会不断变化,采用FLD 作为其失效准则会严重低估其变形能力.近年来,一些学者针对FLD 对应变路径的依赖性提出了很多改进模型,如基于极限应力[３]二等效应变[４－５]二极限厚度应变[６]二厚度梯度准则[７－８]等与路

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