Our group specializes in methods for analyzing the response of macroscopic structures composed of microstructured materials. We develop and apply innovative approaches, both theoretical and computational, to accurately capture the influence of microstructural properties on the equivalent behavior of complex materials, integrating these effects into macroscale simulations.
Micro-macro approaches for fibrous materials
From analytical formulations to finite element implementationsThe mechanics of fibers with a crimped microstructure affects the behavior of flexible composites and textiles in advanced engineering applications, such as inflatable structures, sails, protection systems (e.g., air-bags, body armors), medical devices (e.g., wound dressing, surgical replacements), but also novel stimuli-responsive materials.
Over the years, we first developed a beam model for the rational deduction of the three-dimensional mechanical response of anisotropic, inhomogeneous, and curved elastic fibers. The model was later reformulated within a finite-strain kinematics framework under two-dimensional assumptions. Additionally, a novel multiscale finite-element formulation was proposed, incorporating a quasi-analytical core based on the curved beam model to drive material behavior at integration points.
Our efforts pave the way for new material design approaches aimed at optimizing structural response at the microstructural fiber level. The proposed multiscale scheme combines the advantages of both analytical and computational approaches, offering low computational costs while maintaining an explicit dependency of the macroscale response on microstructural properties.
The Virtual Element Method for computational homogenization
Multiphysical response of polycrystalline microstructuresPolycrystalline materials are composed of an assembly of crystallites (grains) with different sizes and random orientation of material symmetries. The mechanics of polycrystalline materials governs the response of structural components in a number of engineering fields, such as civil, energy-converting, photovoltaic, thermoelectric superconducting and nanosensing applications.
While the mechanical properties of single grains are generally known, the determination of effective material properties of polycrystalline assemblies is of great interest. The computational homogenization of polycrystalline materials is associated with requests of flexibility with regard to mesh generation and element shapes.
The Virtual Element Method (VEM) permits the use of polygonal/polyhedral elements which perfectly fit grain geometries. We have assessed and demonstrated the advantages of using a VEM formulation for the homogenization of polycrystalline microstructures. Applications cover both elastic properties and electro-magneto-mechanical couplings.
Numerical results show that mesh flexibilities inherited by VEM couple with a reduction of numerical locking phenomena in the presence of strong and random anisotropies.