Abstracts
Emilio Barchiesi
From simple architectures to rich phenomenology: the case of pantographic waveguides
Short abstract:
Pantographic waveguides represent a distinctive class of mechanical metamaterials whose response is governed by the interplay of geometric constraints and nonlinearity. Their architecture, an array of hinge-connected slender elements arranged in a diamond-shaped lattice, enables large deformations with minimal energy cost, followed by a rapid transition to a stiffened regime as the cells approach full extension.
In this talk, I will demonstrate that elastic rarefaction solitary waves can propagate in monolayered pantographic waveguides. The analysis will be conducted within a homogenized continuum framework derived from a discrete lattice model endowed with Hookean interaction potentials.
Chiara Gavioli
Modeling fluid diffusion in partially saturated porous media
Short abstract:
This talk explores fluid diffusion in partially saturated porous media, focusing on how surface tension induces hysteresis in the pressure-saturation relation. We model this via a Preisach operator, leading to a challenging, degenerate $N$-dimensional problem. I will present a convexification argument to prove the existence of solutions, showing how this approach remains valid even when accounting for gravity, viscoelasticity, and saturation-dependent permeability.
Francesco dell'Isola
The Principle of Virtual Work and the Problem of Synthesis of Metamaterials
An old controversy about the most suitable postulation foundation of mechanics revives in the modern problem of the synthesis of metamaterials.
We claim that a large class of Exotic mechanical material properties can be obtained by suitably designing the novel material’s microstructures.
Even if no general synthesis theorem is yet available we give some preliminary results and we underline that the most effective postulation scheme to be used in mechanics has to found it on the principle of virtual work .
Indeed in this framework: i) homogenisation results are more easily obtained ii) generalised continuum models can be consistently formulated, iii) the same conceptual structure is used at micro and macro level and iv) well-posedness results and numerical predictions are more easily obtained.
Pantographic, generalised Hart’s investors and ZAPAB microstructures are presented as examples of obtained synthesised microstructures with numerical and experimental evidence showing their peculiar behaviour.
Yao Shan
Modeling of dynamic issues of high-speed railway subgrade
Short abstract:
The operational safety of high-speed trains (operating at speeds approaching 400 km/h and even higher) is highly sensitive to track irregularities. Such irregularities occur far more frequently on subgrade sections than on bridge and tunnel sections. This presentation introduces subgrade dynamic modeling in three parts:
- First, macroscopic models of the vehicle–track–subgrade coupling system in both the time and frequency domains are presented, along with the dynamic responses induced by stiffness irregularities.
- Second, the mesoscopic mechanical evolution of subgrade soil under high-frequency dynamic loads and its corresponding modeling method are illustrated.
- Third, the predictive modeling of subgrade deformation caused by adjacent construction activities is discussed.
