Bifurcation based mechanisms for elastic metainterfaces

Towards the design of innovative elastic metainterfaces, rigid-elastic mechanisms based on bifurcation phenomena are developed and analysed under quasi-static and dynamic loading conditions. In particular, a rigid-elastic mechanism is designed by introducing a strut, which displays a bifurcation at either vanishing tensile or compressive load. Analysis under quasi-static loading shows that such bifurcation allows for devising simple mechanisms with low degrees of freedom, which can exhibit a wide range of mechanical behaviours characterized by multiple stable configurations (from monostable to tetrastable states within a narrow range of deformations). Within this context, a bifurcation mechanism is proven to be mechanically equivalent to a unilateral constraint, a finding instrumental in enabling numerical solutions for the treatment of dynamics. Vibration analysis reveals the inherent non-smoothness in the dynamic response of the considered structural system, similarly to the rocking motion of rigid bodies. Due to the presence of the unilateral constraints, dissipation mechanisms may emerge from impacts of each layer, in addition to that occurring when damping sources are continuous in time. A complex behaviour under dynamic settings is observed with the coexistence of multiple stable attractors (dynamic equilibria) as well as quasi-periodic and chaotic regions in the space parameters, the latter possibly comprising stable attractors too. It is also found that the dynamic effects reduce the monostability region of loading conditions, by enlarging that of multistability. The obtained results show the potential in harnessing bifurcation phenomena as design practice, that can lead to mechanisms with highly desirable mechanical properties, without compromising the global stability of the system. Moreover, the multistable and multisource dissipation mechanisms embedded in these concepts, open new possibilities in coupling vibration attenuation and control with energy harvesting, thus paving the way towards more sustainable solutions.