A CADR seminar by Dr Yue Yuan was held on 21st January at School of Engineering.
As a part of CADR seminar series, a seminar on 'Symmetry and bifurcations of vibro-impact systems' was held at Engineering Seminar Room (FNB 185). The talk was by Dr Yue Yuan, associate professor at School of Mechanics and Engineering at Southwest Jiaotong University, Chengdu. Dr Yue Yuan is a visiting research assistant at CADR, University of Aberdeen.
The presentation was about vibro-impact systems. Because of the existence of impacts, the vibro-impact system is discontinuous and strongly non-linear, such as hammer-like devices, rotor-casing dynamical systems, heat exchangers, fuel elements of nuclear reactor, gears, piping systems, wheel-rail interaction of high speed railway coaches. Researches into the dynamic behavior of vibro-impact systems have important significance in optimization design of machinery and noise suppression. Hence, the complication of the dynamics of vibro-impact system has received great attention. A great deal of issues on vibro-impact dynamics interest many researchers greatly, but little attention has been paid to the symmetry characteristic of the Poincaré map and its influence on possible bifurcations in vibro-impact systems. For the three-degree-of-freedom vibro-impact system with symmetric two-sided constraints, it is certain that the Poincaré map has some symmetry property, which suppresses period-doubling bifurcation, Hopf-flip bifurcation and pitchfork-flip bifurcation of the symmetric period n-2 motion. When the control parameter changes successively, symmetry-breaking bifurcation and symmetry-restoring bifurcation will occur at some point, and the attractor may change between symmetry and antisymmetry repeatedly. It is shown that the unsymmetric implicit map captures the symmetry of the dynamics.