On the design of performance-based pentamode bearings

Abstract

Pentamode lattices are particular metamaterials belonging to the class of extremal materials, which feature a primitive unit cell equipped with four rods meeting at a point. The potential of confined pentamode lattices in different engineering fields, such as, e.g., structural engineering, has not been largely explored yet. In this area, what is particularly interesting is the confinement of pentamode structural "crystals" between stiffening plates for the design of novel impact or seismic protection devices. Such a research line has recently appeared in the literature, with the aim of developing performance-based, vibration-isolation devices. The present study makes use of discrete-to-continuum approaches to the elastic moduli of pentamode lattices, and investigates the feasibility of pentamode structures as innovative anti-seismic devices. Experimental results and analytic formulae are employed to understand the mechanics of pentamode structures equipped with rigid and hinged connections, and the role played by design variables characterizing the aspect ratio of the structure and the response of the junctions. The final part of the work deals with the design of pentamode bearings that feature stiffness and strength properties similar to those of a commercial rubber bearing available on the market for the seismic isolation of buildings and bridges.