Investigation of propagative instabilities in aluminium alloy AW5083 [Abstr.] / Marzena Mucha, Lars Rose, Balbina Wcisło, Andreas Menzel, Jerzy Pamin // W: 93RD Annual Meeting of the International Association ... więcej

Investigation of propagative instabilities in aluminium alloy AW5083 [Abstr.] / Marzena Mucha, Lars Rose, Balbina Wcisło, Andreas Menzel, Jerzy Pamin // W: 93RD Annual Meeting of the International Association of Applied Mathematics and Mechanics, May 30th - June 2nd, 2023, Dresden (Germany) : book of abstracts. – Dresden : Technische Universität Dresden, 2023. – S. 228-229. – Tryb dostępu: https://jahrestagung.gamm-ev.de/wp-content/uploads/2023/05/20230517_BookofAbstracts_final_red.pdf. – Tyt. źródła wg okł. – Data wyd. wg daty konf.

Materials such as steel and aluminium, which are of main importance from an industrial application point of view, can exhibit so-called propagative instabilities, i.e. the Lueders bands and the Portevin ... więcej

Materials such as steel and aluminium, which are of main importance from an industrial application point of view, can exhibit so-called propagative instabilities, i.e. the Lueders bands and the Portevin Le-Chatelier (PLC) effect. They can appear simultaneously or separately along one loading path, depending on strain rate and temperature conditions. When plastic yielding occurs during tensile loading, strains can localise in a shear band, which is typically accompanied by (macroscopic) softening. The plastic front of such band can move through the sample upon further straining. When the material hardens, uniform deformation is retrieved. This phenomenon is called Lueders band formation. The PLC effect is commonly associated with Dynamic Strain Aging and related to negative strain rate sensitivity. Plastic deformation at the macroscopic level results from the initiation and motion of dislocations, whereby the motion can be stopped by solute atoms causing the dislocations to pile up. For continued loading and sufficiently large increase in stress the dislocations start to move again and the process repeats. In phenomenological description this is reflected by repetitive changes from hardening to softening in the related force-elongation diagram (serrations), while localised strain bands occur and propagate in the sample. Thereby, different PLC types can be distinguished. Type A bands propagate continuously and appear at lower temperatures and higher strain rates. Type B bands travel in a hopping manner and occur at medium temperatures and medium strain rates. Type C bands nucleate randomly and appear at higher temperatures and lower strain rates. This work is focused on the analysis of the Lueders bands and the PLC effect for aluminum alloy AW5083. Experiments on dog-bone shape specimens under tension have been performed for three strain rates. For all strain rates considered, Lueders bands are first observed, followed by (macroscopic) saturation-type hardening with PLC serrations. Moreover, different PLC types are observed. In order to computationally predict both the phenomena, a large strain thermo-visco-plastic model is proposed. Lueders bands are represented by a multi-linear hardening model, whereas the PLC effects are captured by the Estrin-McCormick model. Switch functions are also included in order to activate the respective model contributions. The model is implemented using AceGen/AceFEM for Wolfram Mathematica. A series of simulations are preformed and good agreement between experimental and numerical results is obtained.