On the design of external excitations in order to make nonlinear oscillators respond as free oscillators of the same or different type

Rakaric, Zvonko and Kovacic, Ivana and Cartmell, Matthew (2016) On the design of external excitations in order to make nonlinear oscillators respond as free oscillators of the same or different type. International Journal of Non-Linear Mechanics. ISSN 0020-7462

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    Abstract

    This study deals with nonlinear oscillators whose restoring force has a polynomial nonlinearity of the cubic or quadratic type. Conservative unforced oscillators with such a restoring force have closed-form exact solutions in terms of Jacobi elliptic functions. This fact can be used to design the form of the external elliptic-type excitation so that the resulting forced oscillators also have closed-form exact steady-state solutions in terms of these functions. It is shown how one can use the amplitude of such excitations to change the way in which oscillators behave, making them respond as free oscillators of the same or different type. Thus, in cubic oscillators, a supercritical or subcritical pitchfork bifurcation can appear, whilst in quadratic oscillators, a transcritical bifurcation can take place.