Dr. Kyriakos Alexandros Chondrogiannis

Short Bio

Kyriakos obtained his diploma in Civil Engineering from the National Technical University of Athens (2019), in the discipline of Structural Engineering. He defended his thesis in the field of steel structures, studying the behavior of shell formed wind turbine towers with the use of nonlinear analyses. During his first academic years, Kyriakos participated successfully in technological competitions (f1 in schools, 4x4 in schools) being awarded as world champion. Regarding his professional experience, he has worked in steel structure design and CFD analysis. Kyriakos joined the Chair of Structural Mechanics and Monitoring at ETH Zürich in 2019 as a PhD candidate. His research lies within the “INSPIRE” ITN Marie Skłodowska-Curie research programme, working on metamaterial developments for structural protection.

Research

Nonlinear metamaterial configurations for vibration attenuation

A primary characteristic of civil engineering structures is their response behavior under dynamic excitation, which should comply with comfort and safety standards. Toward such a goal, recent advances in the field of vibration mitigation have leaned towards the use of metamaterials. Metamaterials are artificially designed configurations, which are able to guide or mitigate vibrations within specific frequencies. Typically, metamaterials are arranged in repeating patterns of a fundamental configuration, called the unit cell. 

In most implementations, the unit cell design follows a linear behavior. However, purely linear response usually results in the formation of narrow bandgaps, meaning that the favorable properties of the metamaterial are observed for limited frequencies. A promising idea towards improving the efficiency of such configurations is the inclusion of nonlinearities in the unit cell scale. The implementation of nonlinear metamaterials for vibration mitigation introduces novel capabilities in the field of structural protection against dynamic phenomena.

Design concepts of nonlinear metamaterial designs with potentially favorable properties will be developed. Utilizing nonlinear or unique phenomena, such as geometric nonlinearities, negative stiffness and impacts, vibration mitigation will be pursued. Following analytical results and numerical analyses, selected metastructures will additionally be investigated experimentally.