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On the Interaction of Material Heterogeneity and Geometric Discontinuity in Serrated Plastic Flows

W.  TONG, Y. XUAN, H. YAO

Abstract


Some new experimental results are presented on the evolution of jerky plastic flow and associated localized plastic strain fields in Al-Mg sheet metals under quasi-static loading conditions. Effects of plasticity-induced material heterogeneity on the nucleation and growth of deformation bands over a nominally homogenous macroscopic stress field were first characterized using the standard uniaxial tension coupon geometry. Subsequently, test coupons with U- and V-shaped notches were used to characterize the notch-tip deformation fields subjected to a heterogeneous macroscopic stress field due to geometric discontinuity of notches. Experiments were carried out using both hard and soft test machines and limitations and uncertainties in the experimental measurements were critically examined. These experimental observations motivated a possible new modeling approach towards plausible explanations of the observed serrated plastic flow phenomena.

Keywords


dynamic strain aging; Portevin-Le Chatelier effect; digital image correlation; localized deformation band; ductile fractureText

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