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    • Keywords


      Jerky flow; Portevin-Le Chatelier effect; dislocations; chaos; correlation dimension; Lyapunov exponent; singular value decomposition; surrogate analysis

    • Abstract


      Sometime ago Ananthakrishna and coworkers had predicted the existence of chaos in jerky flow based on a nonlinear dynamical model consisting of the time evolution equations for three types of dislocations and an equation for the evolution of the stress. Our main focus here is to report the verification of this prediction by analysing the stress signals obtained from samples of AlCu alloys subjected to a constant strain rate test. The analysis of the stress signals is carried out by using several methods. The analysis shows the existence of a finite correlation dimension and a positive Lyapunov exponent. We also carry out a surrogate analysis of the time series to ascertain that the signals are not from a power law stochastic process. From the analysis we find that the minimum number of variables required for a dynamical description of the jerky flow appears to be four or five, consistent with the number of degrees of freedom envisaged in the model.

    • Author Affiliations


      S J Noronha1 G Ananthakrishna1 L Quaouire2 C Fressengeas2

      1. Materials Research Centre, Indian Institute of Science, Bangalore - 560 012, India
      2. Laboratoire de Physique et Mécanique des Matériaux, U R A 1215 C N R S, Institut Supérieur de Génie Mécanique et Productique, Université de Metz, Ile du Saulcy, Metz Cedex 01 - 57045, France
    • Dates

  • Pramana – Journal of Physics | News

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