Multiscale Modeling Approach to Acoustic Emission during Plastic Deformation

Abstract

We address the long-standing problem of the origin of acoustic emission commonly observed during plastic deformation. We propose a framework to deal with the widely separated time scales of collective dislocation dynamics and elastic degrees of freedom to explain the nature of acoustic emission observed during the Portevin-Le Chatelier effect. The Ananthakrishna model is used as it explains most generic features of the phenomenon. Our results show that while acoustic emission bursts correlated with stress drops are well separated for the type C serrations, these bursts merge to form nearly continuous acoustic signals with overriding bursts for the propagating type A bands.

Large Fluctuations and Dynamic Phase Transition in a System of Self-Propelled Particles

“…representing, for each dumbbell, the work (per unit time) done by the active force. Being proportional to the time averaged projection of the centre of mass velocity v i along the main direction of the dumbbell, this quantity is akin to that measured in the experiments mentioned above [29], and it also represents the entropy production for individual particles (see SM). We call such an observable active work, and the main object of our study is the (2) (with τ = 10) according to the color-code in the bar on the right.…”

“…Addressing the properties of fluctuations occurring at a mesoscopic level in these systems is fundamental for a full characterisation of their functions, as, for instance, in the case of molecular motors [28]. In the context of active brownian motion, large deviations have been studied in experiments with an asymmetric particle interacting with a vibrated granular medium [29]. By considering the fluctuations of a quantity akin to the work defined in Eq.(2), one can test a fluctuation relation [30][31][32] which quantifies the relative probability of small-scale entropy consuming events that go beyond the second principle.In this Letter, we study fluctuations in different systems of interacting active brownian particles propelled by a force directed along their polar axis [18,19,22,33].…”

“…Addressing the properties of fluctuations occurring at a mesoscopic level in these systems is fundamental for a full characterisation of their functions, as, for instance, in the case of molecular motors [28]. In the context of active brownian motion, large deviations have been studied in experiments with an asymmetric particle interacting with a vibrated granular medium [29]. By considering the fluctuations of a quantity akin to the work defined in Eq.…”

Акустическая Эмиссия При Взаимодействии Скользящей Дислокации С Точечными Препятствиями

“…Начальная стадия этого процесса, начинающаяся задолго до момента бло-кировки образующегося скопления обратными напряже-ниями, и сопровождающего его излучения моделирова-лась в работах Нацика и Чишко [3,4]. Теоретические расчеты акустической эмиссии при пластической дефор-мации с коллективным движением дислокаций [5] пока-зывают, что релаксация напряжений начинается с мо-мента максимального значения акустического импульса, совпадающего по времени с максимальным значением напряжений в кристалле. В то же время полученная при этом кривая напряжения не совсем точно описывает реальный процесс деформирования ни с точки зрения опытных данных [6], ни с точки зрения результатов моделирования [7].…”

Influence of system size on spatiotemporal dynamics of a model for plastic instability: Projecting low-dimensional and extensive chaos

“…These serrations are associated with heterogeneous deformation [1,11]. While dislocation activity in the sample is not accessible to experiments, dislocation bands seen on the surface of the sample [1,12] together with the nature of accompanying acoustic emission signals [13,14] strongly suggest that the collective dislocation dynamics is intermittent at the microscopic level. The nature of the stress signals while remaining irregular throughout the instability domain changes with the applied strain rate.…”