An Enhanced Viscoplastic Constitutive Model for Semi-Solid Materials to Analyze Shear Localization

Subject Areas : Engineering

M.H Sheikh-Ansari ¹ , M Aghaie-Khafri ²

1 - Faculty of Materials Science and Engineering, K.N. Toosi University of Technology, Tehran, Iran
2 - Faculty of Materials Science and Engineering, K.N. Toosi University of Technology, Tehran, Iran

Received: 2018-08-05 Accepted : 2018-10-05 Published : 2018-12-30

Keywords: Semi-Solid, Viscoplastic model, Shear band, Perturbation growth, Dilatancy,

Abstract :

Semi-solid materials undergo strain localization and shear band formation as a result of granular nature of semi-solid deformation. In the present study, to analyze the shear localization, a unified viscoplastic constitutive model was developed for the homogeneous flow. Then, a linearized analysis of the stability performed by examining the necessary condition for the perturbation growth. For this purpose, a shear layer model was considered to analyze the perturbation growth and subsequent instability. The perturbation analysis revealed that the failure mode in semi-solid materials is diffused with long wave length regime, rather than to be localized and exhibiting short wave length regime. Moreover, decreasing the solid skeleton has a retarding effect on the perturbation growth and localization at low and modest strain rates. The performed analysis showed that the localization analysis results in a new interpretation for the micro-mechanisms of the semi-solid deformation. The constitutive model was fairly well correlated with the experimental results.

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