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Dynamic failure mechanism of copper foil in laser dynamic flexible forming

Shen Zongbao, Zhang Lei, Li Pin, Liu Kai, Lin Youyu, Zhou Guoyang, Wang Yang, Zhang Jindian, Liu Huixia, Wang Xiao

Materials Science Poland

2020

Vol. 38, No. 4

684--692

Laser dynamic flexible forming (LDFF) is a novel high velocity forming (HVF) technology, in which the foil metal is loaded by laser shock wave. Strain localization is readily to occur around the bulge edge, which will result in the ultimate dynamic failure. In this work, the microstructures before and after dynamic fracture are characterized by transmission electron microscopy (TEM) to investigate the dynamic failure mechanism. The plastic deformation regions of copper foil are composed of shock compression, strain localization and bulge. Microstructure refinement was observed in three different plastic deformation regions, particularly, dynamic recrystallization (DRX) occurs in the strain localization and bulge regions. In bulge region, extremely thin secondary twins in the twin/matrix (T/M) lamellae are formed. The microstructure features in the strain localization region show that superplastic flow of material exists until fracture, which may be due to DRX and subsequent grain boundary sliding (GBS) of the recrystallized grains. The grain coarsening in strain localization region may degrade the material flowing ability which results in the dynamic fracture.

Dynamic failure of salt interchamber pillars.

Baryakh A., Asanov V., Gheghin A., Toksarov V., Pankov I.

Prace Naukowe Instytutu Geotechniki i Hydrotechniki Politechniki Wrocławskiej. Konferencje

2001

Vol. 73, nr 40

5-13

The problem of dynamic failure of salt interchamber pillar is considered. Through theoretic investigations made, the possibility of the said above phenomena at momentary ceiling caving in conditions of multi-bed mining is shown. According to the results of physical modeling, dynamic effects in pillars may occur during the caving of the ceiling having a considerable thickness. As for Upper Kama Deposit, the elastic features of salt rocks of upping strata, by which the danger of dynamic failure of pillars may be conditioned, are defined.