PROPAGATION CHARACTERISTICS OF PORTEVIN-LE CHATELIER BANDS
The Portevin-Le Chatelier (PLC) bands are traditionally classified into three types:type A are bands which propagate continuously along the specimen,and are observed at higher strain rates.Type B are bands move in a discontinuous manner,appear at lower strain rates,and give rise to the characteristic PLC serrations,or jerky flow; in some cases type C bands are observed,which nucleate at random sites along the specimens gauge length. Laser speckle method and modeling are used to show that significant elastic shrinkage of the whole specimen is associated with type B or C bands,while the elastic shrinkage is negligible in the case of type A bands.Detailed observation of the propagation of type A bands shows a fine structure of serrations,of minute magnitude,in such a way that macroscopic elastic relaxation is not possible,hence the bandscontinuous propagation.It is concluded that the differentiation between A,B and C types is rather artificial,as whether one type of band or another is observed depends only on the ratio between the externally imposed strain rate and that of the band,where as the fundamental physics of the bands formation and propagation remain unaltered by the strain rate.Further experiments and numerical modeling support these conclusions1,2,3.The findings are discussed in terms of current theories for the PLC effect.
Portevin-Le Chatelier bands elastic shrinkage numerical simulation
H.B.Chen Q.C.Zhang X.P.Wu
CAS Key Laboratory of Mechanical Behavior and Design of Materials,University of Science and Technology of China,Hefei,Anhui 230026,China
国际会议
第二届国际非均质材料力学会议(The Second International Conference on Heterogeneous Material Mechanics)
安徽黄山
英文
1447
2008-06-03（万方平台首次上网日期，不代表论文的发表时间）