Chaos and the jerky flow in Al-Mg polycrystals

The stress versus time signals generated in Al-3%Mg polycrystalline samples deformed in constant strain rate have been analysed in order to check the prediction that jerky flow should exhibit chaotic behaviour. The analysis was carried out with the help of several complementary methods, showing the existence of a finite correlation dimension and a positive Lyapunov exponent. The results unambiguously show the existence of chaos resulting from the non-linear interaction of four or five degrees of freedom.