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Onset of chaotic dynamics in a ball mill: attractors merging and crisis induced intermittency

Manai, Giuseppe and Delogu, Francesco and Rustici, Mauro (2002) Onset of chaotic dynamics in a ball mill: attractors merging and crisis induced intermittency. Chaos, Vol. 12 (3), p. 601-609. eISSN 1089-7682. Article.

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DOI: 10.1063/1.1484016

Abstract

In mechanical treatment carried out by ball milling, powder particles are subjected to repeated high-energy mechanical loads which induce heavy plastic deformations together with fracturing and cold-welding events. Owing to the continuous defect accumulation and interface renewal, both structural and chemical transformations occur. The nature and the rate of such transformations have been shown to depend on variables, such as impact velocity and collision frequency that depend, in turn, on the whole dynamics of the system. The characterization of the ball dynamics under different impact conditions is then to be considered a necessary step in order to gain a satisfactory control of the experimental set up. In this paper we investigate the motion of a ball in a milling device. Since the ball motion is governed by impulsive forces acting during each collision, no analytical expression for the complete ball trajectory can be obtained. In addition, mechanical systems exhibiting impacts are strongly nonlinear due to sudden changes of velocities at the instant of impact. Many different types of periodic and chaotic impact motions exist indeed even for simple systems with external periodic excitation forces. We present results of the analysis on the ball trajectory, obtained from a suitable numerical model, under growing degree of impact elasticity. A route to high dimensional chaos is obtained. Crisis and attractors merging are also found.

Item Type:Article
ID Code:367
Status:Published
Refereed:Yes
Uncontrolled Keywords:Nonlinear dynamical systems, chaos, impact (mechanical), materials preparation, machining, plastic deformation, fracture mechanics
Subjects:Area 03 - Scienze chimiche > CHIM/02 Chimica fisica
Divisions:001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:American Institute of Physics
eISSN:1089-7682
Additional Information:Pubblicato online il 18 luglio 2002.
Deposited On:18 Aug 2009 10:02

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