Abstract
The paper deals with the investigation of the temporal instabilities and spatial localization due to the Lüders behavior and the Portevin–Le Chatelier effect in the carbon steel C1010 and the aluminummagnesium alloy AA5052, which manifest the unstable plastic flow. The digital image correlation technique and the infrared thermography were used to capture and study the processes of the initiation and propagation of the deformation bands. The main part of the research focuses on the estimation of the influence of the loading system’s stiffness on the irregular plastic flow, which was carried out on flat specimens with complicated geometry and on specimens with additional deformable parts.
Highlights
The experimental study of the mechanical behavior of the structural materials and the spatial-time inhomogeneity of plastic deformation is an important subject in mechanics of deformable solids
Despite the considerable investigations that have been conducted on the effects of the inelastic deformation and the irregular plastic flow, the yield delay effect and the PLC effect is still debated
Some research deals with the influence of specimen geometry [5, 6] and chemical composition [4], other research estimates the influence of loading conditions and external test parameters on the PLC effect [7,8,9,10] and the Lüders behavior [11, 12]
Summary
The experimental study of the mechanical behavior of the structural materials and the spatial-time inhomogeneity of plastic deformation is an important subject in mechanics of deformable solids. Cottrell put forward the theoretical description of the upper/lower stress, in which case the yield point on the stress-strain curve explained by dislocation theory at the microscopic level It is well known, that aluminum-magnesium alloy manifests the Savart-Masson effect in conditions of the strength loading ( ε 0 const ) or the Portevin-Le Chatelier effect in conditions of the kinematic loading ( σ 0 const ) in a given range of temperature and strain/stress rate [1,2,3]. The DIC-technique and IR-analysis were applied to observe the evolution of the inhomogeneous strain and temperature fields, and to study the morphology and kinetics of the deformation bands in metals during uniaxial tension tests. The initiation and propagation of the Lüders and the PLC bands were carried out on specimens with complicated geometry
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