Feasibility evaluation of failure models for predicting forming limit of metal foils  

作　　者：Bao MENG Jiejie SHI Yiyun ZHANG Cheng CHENG Bolin MA Min WAN 

机构地区：[1]School of Mechanical Engineering and Automation,Beihang University,Beijing 100083,China

出　　处：《Chinese Journal of Aeronautics》2020年第9期2461-2471,共11页中国航空学报（英文版）

基　　金：funding support to this research from the National Natural Science Foundation of China(Nos.51605018 and 51635005);Beijing Municipal Natural Science Foundation of China(No.3172022)。

摘　　要：Forming limit of metal foil is an important index to evaluate its formability,and is of considerable significance to improve the quality of products.The ductile fracture(DF)behavior in microscale plastic deformation is remarkably affected by the geometry and grain size.To explore the size-dependent forming limit curve(FLC),the Holmberg and Marciniak tests of SUS304 foils with the thicknesses of less than 0.1 mm and diverse grain sizes were performed.In addition,the validity and feasibility of three types of existing failure models including Swift/Hill,MarciniakKuczynski(M-K)and DF criteria for predicting the micro-scaled FLCs were discussed.It is found that the Swift/Hill model possesses the worst accuracy with predicting deviation above 50%.Four classical DF criteria including Freudenthal,Ayada,Brozzo and Oh show great difference,and Oh model considering plastic anisotropy presents the best precision.The predicted deviation of M-K model is aggravated with increasing grain size and decreasing foil thickness,which is attributed to the intensified free surface roughening and transformation of fracture mechanism with miniaturization.This research thus provides a deeper understanding and valuable reference for the widespread application of FLC in microforming.

关 键 词：Failure criteria Forming limit Metal foil MICROFORMING Size effect 

分 类 号：TG113[金属学及工艺—物理冶金]