Jorge L. P. Felix

Remarks on an Optimal Linear Control Design Applied to a Nonideal and an Ideal Structure Coupled to an Essentially Nonlinear Oscillator

This paper considers a nonlinear dynamics of a particular structure coupled (or uncoupled) to an essentially nonlinear oscillator. We used an optimal linear control design to reduce the amplitude of oscillations and to expand energy consumption, for both ideal and nonideal mathematical models.

Effects of a random loading emulating an irregular terrain in the nonlinear dynamics of a tower sprayer

This paper deals with the nonlinear dynamics of a mechanical system which consists of an orchard tower sprayer, coupled with a vehicle suspension that is subject to random excitations due to soil irregularities. A deterministic mathematical model, where tower is considered as an inverted double pendulum over an vehicle suspension, with three degrees of freedom (one translation and two rotations) is constructed. To take into account the random loadings due to soil variabilities, a parametric probabilistic approach is employed, where the external force is assumed to be a harmonic random process. This stochastic process has random amplitude and frequency, which are modeled as random variables, and a sinusoidal shape in time. The distribution of these random parameters is consistently specified using the maximum entropy principle. The propagation of uncertainties through the stochastic model is computed using the Monte Carlo method. Numerical simulations show large discrepancies in the system response, when compared with nominal (deterministic) model, for the cases studied where the forcing frequency is random. Also, the results shown that the steady state probability distributions are completely different in all the case studied.

ON A NONLINEAR DYNAMICS OF A NON-IDEAL OSCILLATOR, WITH A SNAP THROUGH TRUSS ABSORBER (STTA)

This work considers the vibrating system that consists of a snap-through truss absorber (STTA) coupled to an oscillator under excitation of an electric motor, characterizing a non-ideal oscillator (NIO). It is aimed to use the absorber STTA to establish the conditions that we have the maximum attenuation the jump phenomenon.

On Chaotic Dynamics of a Double Pendulum Arm Excited by a Nonlinear Shaker Based RLC Circuit

The chaotic dynamics of a double pendulum arm coupled to a nonlinear shaker based RLC circuit through a magnetic field is studied numerically. The nonlinear term, in the circuit, is introduced by considering that the voltage of the capacitor is a nonlinear function of the instantaneous electric charge. For the identification of the response of the system various techniques, including chaos techniques as bifurcation diagrams and time histories, power spectral densities (FFT), Poincare maps and exponents of Lyapunov are used. This electromechanical system will represent a basic subsystem of any robot.Copyright