Currently, there is a vast amount of research activity taking place into the development of new materials having unconventional properties and the respective technologies have been opening new eras through various applications for society. This new generation of materials, or metamaterials, have led to interesting physical properties previously thought impossible such as cloaking, negative refraction and materials that contract when heated. Most of those properties are realised in the dynamic response of the material. However, in these dynamic processes uncertainty remains as to whether these metamaterials undergo feasible deformations, remaining intact. Research into the latter is limited. Understanding this phenomenon is important in developing new metamaterials. Additionally it is crucial, for example, in larger structures such as multi-span bridges (see Fig 1(a)), pipelines and skyscrapers exposed to earthquakes and terrorist attacks, regularly faced in Europe and their effects can be catastrophic to human life.
Fig 1: (a) The Rio-Niterói Bridge connecting Rio de Janeiro and Niterói in Brazil (image from https://www.telegraph.co.uk). (b) A structured medium, composed of periodically placed point masses connected by. beams. The structure contains a propagating crack, that this failure process can be modelled mathematically. The model may represent failure propagation within the deck of a bridge.
The primary scientific objective of CAT-FFLAP is to model dynamic failure propagation in complex structured media. As an example, let us consider a crack propagating in a structure (in Fig 1(b)) composed of periodically placed masses (at the junctions) connected by beams. The structure is loaded remotely by some mechanical or thermal load. We ask, can one predict the dynamic failure phenomenon associated with the propagation waves in this structure? More specifically, is the crack propagation regular or non-regular? What speed does it possess? What dynamic processes appear as a result of this failure? Does the fracture process settle to some steady-state? What load is required to initiate and support the fracture propagation? All these questions are of relevance in practical applications, but are largely unaddressed in research into metamaterials.
It is envisaged that addressing these questions within this project will lead to designs for new materials capable of inhibiting the initiation and propagation of failure. It will also provide new pathways to controlling the flow of vibrations in structured materials in order to mitigate their effects. Some research topics considered in this project involve
- Waves and dynamic failure propagation in flexural multi-scale systems and
- Seismic metamaterials, design and earthquake protection.
Acknowledgement: Michael Nieves gratefully acknowledges the support of the EU H2020 grant MSCA-IF-2016-747334-CAT-FFLAP.