PhD Graduate

PhD program:: XXXIII

supervisor: Ing. Gianluca Pepe
advisor: Prof. Antonio Carcaterra

Thesis title: Wave effects in long-range connectivity: homogeneous and non-homogeneous periodicity

Metamaterials are artificial composites, developed to exhibit specific properties. Their characteristics majorly stem from the tailored structure itself rather than its composing materials. What drew attention to this family is the exotic behaviours they inherently present, which is unusual with respect to those observed in nature. Acoustic metamaterials, in particular, could provide attractive features for practical purposes, including cloaking and noise cancelling. A second original viewpoint on metamaterials suggests the possibility of enjoying the tantamount effects by introducing a domain within which distant points interact mutually. Thus, developing distinct configurations through embedding long-range connectors within host structures could provide the potential to manipulate wave paths across the domain. Bearing in mind the need for a wide variety of propagation phenomena in different applications, systems with long-range inclusions, which challenges the common notion of exclusive first neighbour interaction, could be a potential candidate. By initiating the graph-periodicity concept, two major categories of long-range configurations are introduced, namely long-range homogenous and non-homogenous systems. With reference to the graph-periodicity concept, genuine periodic configuration can be built, where the system captures the tree-periodicity property. In this case, due to the contribution of select groups of points in constructing the configuration, a non-homogenous periodic configuration is met. On the other hand, long-range homogenous configurations are those in which all points adhere to an identical connectivity template. Although such arrangements are not genuinely periodic (no tree-periodicity), they can be leaf-periodic depending on the template. This thesis presents the analysis of wave propagation in conventional structures, namely waveguide, membrane and shell, integrated with long-range connector. Regarding long-range homogenous configurations, the long-range forces are modelled by summation and integral terms. The long-range operators are majorly modelled by simple spring-like connections, and in some instances by resonator units. Wave propagation behaviour of the system is comprehensively realized by examining the dispersion relation, obtained analytically. Several phenomena, including wave-stopping, negative group velocity, and redistribution of eigenstates, are observed under different circumstances depending on the comparative stiffness of long-range connections. Next, the problem of wave propagation in long-range non-homogenous periodic configurations is investigated. Although extracting the dispersion curves for such systems is not a trivial task due to non-homogeneous distribution of long-range connectors, the adopted connectivity template provides the opportunity to take the advantage of the well-known Floquet theorem to identify the band structure. The emergence of gaps over the frequency band is confirmed. The model implies the possibility of pulling the gaps towards ultra-low frequencies and even generating stopbands, which could virtually open from zero, when connections assume negative stiffness. Insertion loss analysis is performed to roughly validate the arrangements of stopbands over the frequency band, yielded by the Floquet theorem. Given the fact that human beings are social creatures, this creates several layers of human interactions yielding a giant network of intercommunications in societies. Thus, mathematical modelling, analogous to the above, could be a big asset to shed light on behaviour of crowds in large scale. Correspondingly, dynamic memory, being the temporal counterpart of spatial long-range interactions, can be included in some long-established problems such as natural economic growth to achieve a more effective and accurate description of the system. Current study exclusively considers the effect of nonlocal interactions in the realm of physics and engineering though the underlying message conveyed by this concept can be extremely relevant in other fields as well.

Research products

11573/1640958 - 2022 - Research facilities for europe’s next generation gravitational-wave detector einstein telescope
Di Pace, Sibilla; Mangano, Valentina; Pierini, Lorenzo; Rezaei, Amirsajjad; Hennig, Jan-Simon; Hennig, Margot; Pascucci, Daniela; Allocca, Annalisa; Tosta E Melo, Iara; Nair, Vishnu; Orban, Philippe; Sider, Ameer; Shani-Kadmiel, Shahar; Van Heijningen, Joris - 01a Articolo in rivista
paper: GALAXIES (Basel, Switzerland: MDPI AG) pp. - - issn: 2075-4434 - wos: WOS:000815921300001 (12) - scopus: 2-s2.0-85133171663 (15)

11573/1640964 - 2022 - Long-range resonator-based metamaterials
Rezaei, Amirsajjad; Mezzani, F.; Carcaterra, A. - 04b Atto di convegno in volume
conference: Second international nonlinear dynamics conference, NODYCON 2021 (Rome)
book: Advances in nonlinear dynamics - (978-3-030-81169-3; 978-3-030-81170-9)

11573/1640967 - 2022 - Analytical buckling response of sectorial porous plates integrated with piezoelectric layers
Sadeghi Gughari, M.; Saidi, A. R.; Rezaei, Amirsajjad.; Askari, M.; Naderi, A. - 01a Articolo in rivista
paper: APPLIED MATHEMATICAL MODELLING (-USA, NY,: ELSEVIER SCIENCE INC -Burlington, MA: Butterworth Heinemann Publ) pp. 811-831 - issn: 0307-904X - wos: WOS:000708117300001 (9) - scopus: 2-s2.0-85122537714 (12)

11573/1544849 - 2021 - Wave propagation with long-range forces and mistuning effects
Rezaei, A.; Mezzani, F.; Carcaterra, A. - 01a Articolo in rivista
paper: PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS. PART C, JOURNAL OF MECHANICAL ENGINEERING SCIENCE (Professional Engineering Publications:PO Box 24 Northgate Avenue, Bury St. Edmunds, IP32 6BW United Kingdom:011 44 1284 718681, 011 44 1284 724384, EMAIL:, INTERNET:, Fax: 011 44 1284 704006) pp. 095440622198974- - issn: 0954-4062 - wos: WOS:000683099000001 (0) - scopus: 2-s2.0-85100058564 (2)

11573/1349698 - 2019 - Memory effects in wave propagation
Rezaei, Amirsajjad; Mezzani, F.; Carcaterra, A. - 04b Atto di convegno in volume
conference: 26th International Congress on Sound and Vibration, ICSV 2019 (Montreal, Canada)
book: Proceedings of the 26th International congress on sound and vibration - (978-199918100-0)

11573/1236173 - 2018 - An investigation over the effect of piezoelectricity and porosity distribution on natural frequencies of porous smart plates
Askari, M.; Saidi, A. R.; Rezaei, Amirsajjad - 01a Articolo in rivista
paper: JOURNAL OF SANDWICH STRUCTURES AND MATERIALS (London:SAGE PUBLICATIONS LTD Lancaster, PA : Technomic Pub. Co., c1999-) pp. 2091-2124 - issn: 1099-6362 - wos: WOS:000561225700001 (23) - scopus: 2-s2.0-85052602813 (22)

11573/1173658 - 2018 - Waves path in an elastic membrane with selective nonlocality
Coppo, F.; Rezaei, Amirsajjad; Mezzani, F.; Pensalfini, S.; Carcaterra, A. - 04b Atto di convegno in volume
conference: 28th International conference on noise and vibration engineering, ISMA 2018 and 7th International conference on uncertainty in structural dynamics, USD 2018 (Leuven, Belgium)
book: Proceedings of ISMA 2018 - International conference on noise and vibration engineering and USD 2018 - International conference on uncertainty in structural dynamics - (9789073802995)

11573/1236171 - 2018 - An analytical study on the free vibration of moderately thick fluid-infiltrated porous annular sector plates
Rezaei, Amirsajjad; Saidi, A. R. - 01a Articolo in rivista
paper: JOURNAL OF VIBRATION AND CONTROL (Sage Science Press:2455 Teller Road:Thousand Oaks, CA 91320:(800)818-7243, (805)499-0721, EMAIL:, INTERNET:, Fax: (805)499-0871) pp. 4130-4144 - issn: 1077-5463 - wos: WOS:000443291400005 (13) - scopus: 2-s2.0-85029684616 (23)

11573/1123806 - 2017 - On natural frequencies of Levy-type thick porous-cellular plates surrounded by piezoelectric layers
Askari, M.; Saidi, A. R.; Rezaei, Amirsajjad - 01a Articolo in rivista
paper: COMPOSITE STRUCTURES (-OXFORD, ENGLAND: Elsevier Science Ltd -London : Applied Science, 1983-) pp. 340-354 - issn: 0263-8223 - wos: WOS:000410632000024 (28) - scopus: 2-s2.0-85026554462 (30)

11573/1123711 - 2017 - On the effect of coupled solid-fluid deformation on natural frequencies of fluid saturated porous plates
Rezaei, Amirsajjad; Saidi, A. R. - 01a Articolo in rivista
paper: EUROPEAN JOURNAL OF MECHANICS. A, SOLIDS (Gauthier-Villars:15 rue Gossin, 92543 Montrouge Cedex France:011 33 1 40 926500, Fax: 011 33 1 40 926597) pp. 99-109 - issn: 0997-7538 - wos: WOS:000395219600009 (31) - scopus: 2-s2.0-85009415040 (33)

11573/1236163 - 2017 - Buckling response of moderately thick fluid-infiltrated porous annular sector plates
Rezaei, Amirsajjad; Saidi, A. R. - 01a Articolo in rivista
paper: ACTA MECHANICA (Springer-Verlag Wien:Sachsenplatz 4-6, PO Box 89, A-1201 Vienna Austria:011 43 1 3302415, EMAIL:, INTERNET:, Fax: 011 43 1 3302426) pp. 3929-3945 - issn: 0001-5970 - wos: WOS:000413959400013 (28) - scopus: 2-s2.0-85025835896 (29)

11573/1123779 - 2017 - Natural frequencies of functionally graded plates with porosities via a simple four variable plate theory: an analytical approach
Rezaei, Amirsajjad; Saidi, A. R.; Abrishamdari, M.; Pourmohammadi, M. H. - 01a Articolo in rivista
paper: THIN-WALLED STRUCTURES (Elsevier Applied Science:An Imprint of Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington Oxford OX5 1GB United Kingdom:011 44 1865 843000, 011 44 1865 843699, EMAIL: OR OR, INTERNET:, Fax: 011 44 1865 843010) pp. 366-377 - issn: 0263-8231 - wos: WOS:000418106800032 (147) - scopus: 2-s2.0-85029682990 (166)

11573/1123796 - 2016 - Application of Carrera Unified Formulation to study the effect of porosity on natural frequencies of thick porous–cellular plates
Rezaei, Amirsajjad; Saidi, A. R. - 01a Articolo in rivista
paper: COMPOSITES. PART B, ENGINEERING (Oxford : Elsevier, 1996-) pp. 361-370 - issn: 1359-8368 - wos: WOS:000374075100039 (117) - scopus: 2-s2.0-84959348734 (122)

11573/1123754 - 2015 - Exact solution for free vibration of thick rectangular plates made of porous materials
Rezaei, Amirsajjad; Saidi, A. R. - 01a Articolo in rivista
paper: COMPOSITE STRUCTURES (-OXFORD, ENGLAND: Elsevier Science Ltd -London : Applied Science, 1983-) pp. 1051-1060 - issn: 0263-8223 - wos: WOS:000363831900104 (122) - scopus: 2-s2.0-84942636628 (135)

© Università degli Studi di Roma "La Sapienza" - Piazzale Aldo Moro 5, 00185 Roma