In the past D.S. Sophianopoulos has collaborated on articles with G.T. Michaltsos. One of their most recent publications is Complex dynamics of perfect discrete systems under partial follower forces. Which was published in journal International Journal of Non-Linear Mechanics.

More information about D.S. Sophianopoulos research including statistics on their citations can be found on their Copernicus Academic profile page.

D.S. Sophianopoulos's Articles: (3)

Complex dynamics of perfect discrete systems under partial follower forces

AbstractEquilibrium points, primary and secondary static bifurcation branches, and periodic orbits with their bifurcations of discrete systems under partial follower forces and no initial imperfections are examined. Equilibrium points are computed by solving sets of simultaneous, non-linear algebraic equations, whilst periodic orbits are determined numerically by solving 2- or 4-dimensional non-linear boundary value problems. A specific application is given with Ziegler's 2-DOF cantilever model. Numerous, complicated static bifurcation paths are computed as well as complicated series of periodic orbit bifurcations of relatively large periods. Numerical simulations indicate that chaotic-like transient motions of the system may appear when a forcing parameter increases above the divergence state. At these forcing parameter values, there co-exist numerous branches of bifurcating periodic orbits of the system; it is conjectured that sensitive dependence on initial conditions due to the large number of co-existing periodic orbits causes the chaotic-like transients observed in the numerical simulations.

Flexural–torsional vibration of simply supported open cross-section steel beams under moving loads

SummaryThe present work deals with linearized modal analysis of the combined flexural-torsional vibration of simply supported steel beams with open monosymmetric cross-sections, acted upon by a load of constant magnitude, traversing its span eccentrically with constant velocity. After thoroughly investigating the free vibrations of the structure, which simulates a commonly used highway bridge, its forced motions under the aforementioned loading type are investigated. Utilizing the capabilities of symbolic computations within modern mathematical software, the effect of the most significant geometrical and cross-sectional beam properties on the free vibration characteristics of the beam are established and presented in tabular and graphical form. Moreover, adopting realistic values of the simplified vehicle model adopted, the effects of eccentricity, load magnitude and corresponding velocity are assessed and interesting conclusions for structural design purposes are drawn. The proposed methodology may serve as a starting point for further in-depth study of the whole scientific subject, in which sophisticated vehicle models, energy dissipation and more complicated bridge models may be used.

Nonlinear stability of a simplified model for the simulation of double suspension roofs

AbstractThe present work deals with the nonlinear static as well as dynamic stability aspects of an initially imperfect dissipative 2-mass, 3–DOF model under step loading, introduced as a simplified simulation of a class of double-suspension roofs. Employing a fully nonlinear straightforward analysis it is found that global stability, being the main feature of double-suspension roofing systems, is captured by the proposed autonomous conservative model. For realistic combinations of the geometric, stiffness and damping parameters involved the model dealt with is always associated with a stable point attractor response and does not experience either snapping or large amplitude horizontal motions, contrary to recent findings reported for single suspended roof models. Finally, various mathematical and visualization obstacles were encountered, to be overcome by modern commercial software.

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