Search results for " SCIENZA"
showing 10 items of 1301 documents
Multidomain SBEM analysis of two dimensional elastoplastic-contact problems
2012
The Symmetric Boundary Element Method based on the Galerkin hypotheses has found application in the nonlinear analysis of plasticity and contact-detachment problems, but dealt with separately. In this paper we wants to treat these complex phenomena together. This method works in structures by introducing a subdivision into sub-structures, distinguished into macroelements, where elastic behaviour is assumed, and bem-elements, where it is possible for plastic strains to occur. In all the sub-structures, elasticity equations are written and regularity conditions in weighted (weak) form and/or in nodal (strong) form between boundaries have to be introduced, to attain the solving equation system.
When the doctor gets sick: the Eurozone crisis and transatlantic relations
2013
The role of evanescent modes in Global-Local analysis of UGW in plates with varying local zone-scatterer relations
2023
In order to provide a reliable and robust SHM performance, Ultrasonic Guided Waves (UGWs) need to be analyzed and understood. Numerical modeling of UGW propagation and scattering by hybrid methods offers the possibility of simulating UGW interaction with waveguides of arbitrary cross-sections and discontinuities. Maximizing the accuracy of such methods is important to perform quantitative SHM, while maintaining minimum computational cost. This work investigates the role of evanescent modes in the numerical analysis of UGWs in aluminum and composite plates with defects, by the hybrid Global-Local method. The complex solutions to the UGW eigenvalue problem are found and the scattering spectra…
Structural analysis, phase stability and electrochemical characterization of Nb doped BaCe0.9Y0.1O3−x electrolyte for IT-SOFCs
2012
Abstract To improve the chemical stability of high temperature proton conductors based on barium cerate, electrolyte powders doped with different amounts of niobium were synthesized by the citrate–nitrate auto-combustion method. Pure single phases of BaCe 0.9− x Nb x Y 0.1 O 3− x (BCYN, 0.03 ≤ x ≤ 0.12) were obtained by thermal treatment at 1000 °C. Sintering at 1450 °C for 10 h produced dense pellets. X-ray absorption spectroscopy allowed to define the dopant ion insertion site and the co-dopant valency. Treatments in pure CO 2 atmosphere at 700 °C for 3 h and subsequent XRD analysis were carried out to probe the chemical stability of the produced electrolytes. The influence of the prese…
In-process material characterization at constant extrusion conditions: application to clay/PLA bionanocomposites
2017
The authors developed a prototype modular small-scale single / twin-screw extrusion system, with outputs in the range of grams/hour, coupled to a rheo-optical slit die. This experimental set-up is adequate to measure shear viscosity and normal-stress differences and perform optical measurements
Flexible Perfluoropolyethers-Functionalized CNTs-Based UHMWPE Composites: A Study on Hydrogen Evolution, Conductivity and Thermal Stability
2022
Flexible conductive composites based on ultra-high molecular weight polyethylene (UHMWPE) filled with multi-walled carbon nanotubes (CNTs) modified by perfluoropolyethers (PFPEs) were produced. The bonding of PFPE chains, added in 1:1 and 2:1 weight ratios, on CNTs influences the dispersion of nanotubes in the UHMWPE matrix due to the non-polar nature of the polymer, facilitating the formation of nanofillers-rich conductive pathways and improving composites’ electrical conductivity (two to five orders of magnitude more) in comparison to UHMWPE-based nanocomposites obtained with pristine CNTs. Electrochemical atomic force microscopy (EC-AFM) was used to evaluate the morphological changes dur…
Bionanocomposite films containing halloysite nanotubes and natural antioxidants with enhanced performance and durability as promising materials for c…
2020
In the last decade, the interest toward the formulation of polymer films for cultural heritage protection continuously grew, and these films must be imperatively transparent, removable, and should not react/interact with surface of the artworks. In this research, bionanocomposite films, based on chitosan (Ch) and pectin (P) and containing naturally occurring fillers and antioxidants, were formulated by solvent casting methods and were accurately characterized. The natural halloysite nanotubes (HNT) have a two-fold role, specifically, physical compatibilizer and antioxidant carrier. Therefore, the theoretical solubility between Ch and P was estimated considering Hoy&rsquo
An explicit mechanical interpretation of Eringen non-local elasticity by means of fractional calculus
2009
If the attenuation function of strain is expressed as a power law, the formalism of fractional calculus may be used to handle Eringen non-local elastic model. Aim of the present paper is to provide a mechanical interpretation to this non-local fractional elastic model by showing that it is equivalent to a discrete, point-spring model. A one-dimensional geometry is considered; static, kinematic and constitutive equations as well as the proper boundary conditions are derived and discussed.