The Propagation of Longitudinal Waves of Plastic Deformation in a Bar of Material Exhibiting a Strain-Rate Effect

1951 ◽  
Vol 18 (2) ◽  
pp. 203-208 ◽  
Author(s):  
L. E. Malvern

Abstract The theory of propagation of longitudinal waves of plastic deformation is extended to apply to materials in which the stress is a function of the instantaneous plastic strain and strain rate. Solutions are given for an idealized flow law and compared with solutions based upon earlier theories which neglect strain-rate effect.

Author(s):  
Jun-Min Seo ◽  
Sang-Seop Jeong ◽  
Yun-Jae Kim ◽  
Jin Weon Kim ◽  
Chang-Young Oh ◽  
...  

Abstract In this study, tensile tests of 304 and 316 austenitic stainless steels at various strain rate were performed to investigate the strain rate effect on tensile properties. It is shown that the strain rate effect on stress depends not only on the strain rate but also on the plastic strain level. Accordingly, a modification of the existing Johnson-Cook model is proposed to incorporate the interacting effect of plastic strain and strain rate for 304 and 316 austenitic stainless steels. Although improvement is not significant, the proposed modified Johnson-Cook model can reduce the difference from the experimental data at various strain levels, compared to the existing Johnson-Cook model.


2009 ◽  
Vol 18 ◽  
pp. S54
Author(s):  
Andrew T. Burns ◽  
Andre La Gerche ◽  
David L. Prior ◽  
Andrew I. MacIsaac

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 77
Author(s):  
Shang Gao ◽  
Honggang Li ◽  
Renke Kang ◽  
Yu Zhang ◽  
Zhigang Dong

To clarify the influence mechanism of strain rate effect on deformation characteristics of aluminum nitride (AlN) ceramics, some varied-velocity nanoscratching tests were carried out using a Berkovich indenter in this paper. The deformation characteristics of the scratched grooves were observed using the scanning electron microscope. The experimental results showed higher scratch speed would lead to shallower penetration depth, fewer cracks, and indenter fewer slipping, which was more conducive to the plastic deformation of AlN ceramics. Considering the strain rate effect and the elastic recovery of material, a model for predicting the Berkovich indenter penetration depth under edge-forward mode was established. The prediction results were consistent with the experimental data, and the error was less than 5%, indicating that the model is effective. Based on the Boussinesq field, the Cerruti field, and the Sliding bubble field, a strain rate dependent scratch stress field model was established. The stress field revealed higher scratch speed may significantly reduce the maximum principal stress in the stress field under the indenter, which is the fundamental reason for reducing the crack damage and promoting the plastic deformation. The above study can provide theoretical guidance for reducing the processing damage of AlN ceramics.


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