Bifurcations and Crises in a Shape Memory Oscillator

The remarkable properties of shape memory alloys have been motivating the interest in applications in different areas varying from biomedical to aerospace hardware. The dynamical response of systems composed by shape memory actuators presents nonlinear characteristics and a very rich behavior, showing periodic, quasi-periodic and chaotic responses. This contribution analyses some aspects related to bifurcation phenomenon in a shape memory oscillator where the restitution force is described by a polynomial constitutive model. The term bifurcation is used to describe qualitative changes that occur in the orbit structure of a system, as a consequence of parameter changes, being related to chaos. Numerical simulations show that the response of the shape memory oscillator presents period doubling cascades, direct and reverse, and crises

Analysis of smart magnetoelectric reinforced plates

ICCM International Conferences on Composite Materials Volume 2015-July, 2015© 2015 International Committee on Composite Materials. All rights reserved. A comprehensive micromechanical model for the analysis of smart composite and reinforced piezo-magneto-thermo-elastic thin plates is developed on the basis of asymptotic homogenization. The model is used to determine the effective properties of wafer-type magnetoelectric composite plates reinforced with smart ribs or stiffeners oriented along the tangential directions of the plate. For generality, it is assumed that the ribs and the base plate are made of different orthotropic materials. It is shown in this work that in the case of the purely elastic case, the results of the derived model converge exactly to previously established relations. However, in the more general case whereby some or all of the phases exhibit piezoelectric and/or piezomagnetic behavior, the expressions for the derived effective coefficients are shown to be dependent on not only the elastic properties of the constituent materials but also on the piezoelectric and piezomagnetic parameters. Thus, the formulae presented here represent an important refinement of previously established results