1,721,095 research outputs found
UNA METODOLOGIA INVERSA A CORRELAZIONE DI IMMAGINI DIGITALI PER LEGGERE IL COMPORTAMENTO COSTITUTIVO DI GIUNTI ED INTERFACCE
No full textAbstract Brev
Simultaneous Assessment of Mechanical Properties and Boundary Conditions Based on Digital Image Correlation
Full text linkIn this study, reference is made to a mixed
numerical-experimental methodology proposed in Fedele
et al. (J Mech Physics Solids 57(7):1003–1016, 2009),
based on full-field kinematic measurements at the microscale
provided by 2D Digital Image Correlation. The aim
was to estimate mechanical properties of joints or interfaces
in industrial manufacts. An adhesively bonded assembly
for aerospace engineering was characterized by the above
methodology, optically monitoring a small subdomain over
the sample surface during non-conventional mixed mode
experiments. An extension of the original approach is proposed
herein, since the estimation of cohesive parameters,
and the identification of the “actual” displacements to be
prescribed locally along the boundary, are tackled simultaneously in a coupled framework. Due to ill-posedness and high dimensionality of the extended inverse formulation,
exceeding a few thousand unknowns, recourse is made to an
alternating minimization strategy. Suitable regularizing provisions are implemented, concerning the a priori regularity
of boundary displacements and an equilibrium (Neumann)
condition along the debonded part of the joint
Metodologie a confronto per la stima dell'incertezza in problemi di identificazione parametrica
No full textAssessment of bonding stresses between FRP sheets and masonry pillars during delamination tests
No full textUnder the simplifying assumption of perfect adhesion, motivated by the wide adoption of highly resistant glues, delamination of FRP-reinforced masonry pillars turns out to be governed exclusively by the nonlinear behavior of the quasi-brittle, heterogeneous support. However, at the structural level, the macroscopic delamination response can be described effectively by concentrating all the sources of dissipation and non-linearity at the masonry-FRP interface, and assuming the support to behave as a linear-elastic body. In this paper, a detailed and critical comparison between two different fully three-dimensional
finite element models is developed: (i) a model in which only masonry (i.e. brick and mortar independently) is damageable whilst the FRP reinforcement adheres perfectly to the support (namely, exclusively bulk damage is accounted for), and an alternative model (ii) in which a cohesive, zero thickness interface between the FRP and the support is considered (i.e. interface damage), whilst masonry behaves as a heterogeneous linear elastic material. The overall response during delamination and local stress distributions at the interface are critically investigated, varying the FRP reinforcement width
Caratterizzazione di proprietà meccaniche e di stati tensionali nelle dighe con prove locali in situ e reti neurali artificiali
No full textOne page abstrac
Simultaneous assessment of interface mechanical parameters and boundary conditions, on the basis of kinematic measurements at the microscale
No full textEzio De Felice, dal disegno di oggetti al design del gioiello, 12 marzo
No full textEzio De Felice è un entomologo sui generis - dialoga in versi vernacolari con luoghi, persone e anemalucce, cerca di leggerli con modalità differenti, studia l’organizzazione perfetta di questi organismi elementari che “a torme stanno nel mondo insieme a noi” .
‘’Forse una delle motivazioni che lo spinge a tanto è per lui, maestro di Restauri (e dunque aduso alle grandi come alle piccole misure), il fascino che esprime il minuscolo, l’infinitamente piccolo, al quale questa volta egli accosta con goloso interesse la sua lente di ingrandimento [...] De Felice etnomorfizza il lettore, lo costringe ad osservare il brulicante micromondo oggetto delle sue acute osservazioni poetiche dall’angolazione dell’oggetto stesso” (Santanelli M.,1999).
De Felice cuce pietre dure e rottami li compone, li assembla, disegna, fino a quando nel 1969 viene invitato a Parigi a esporre queste sue strane composizioni ad una mostra collettiva con Lucio Fontana e Picasso. I volti tracciati nei disegni preparatori di questi gioielli non sono più mortificati dalla guerra, ma diventano delle facce ironiche, smorfie, caricature nelle quali gli occhi sono perline, la bocca una spilla. Nel grande Teatro dello studio di Palazzo Donn'Anna è accolta temporaneamente anche la collezione di circa 600 monili in tartaruga, acquistata dai coniugi De Felice Sbriziolo dalla vedova di un insigne corallaro. Pettini, pettinesse, ornamenti sono custoditi insieme ai fogli di carta velina sagome dei merletti e dei trafori, fino alla successiva donazione dell’ampia raccolta al Museo Duca di Martina
Delamination of FRP reinforced masonry pillars: numerical analyses and design considerations
No full textIn this communication, a heterogeneous, fully three-dimensional finite element model is presented, suitable to simulate delamination phenomena of FRP strips glued to masonry.
Both mortar and bricks are modeled independently in tension and compression, through different isotropic damage variables and activation criteria. Reference is made to a masonry pillar, constituted by three Italian standard bricks and two mortar joints, reinforced by a perfectly-adherent FRP external sheet, and subjected to a conventional delamination test.
The overall response in terms of reaction force versus tangential slip, and the three dimensional collapse mechanisms are investigated, induced by different boundary conditions and mechanical properties of the constituent materials. In particular, the dependence of nominal strength and overall ductility on FRP width is investigated. Numerical predictions are compared to those provided by the Italian recommendation CNR DT200, with the aim of highlighting pros and cons of design formulae
A numerical insight into the response of masonry reinforced by FRP strips.The case of perfect adhesion
No full textIn this study a heterogeneous model at the meso-scale is presented, suitable to interpret delamination
phenomena of FRP strips glued to masonry. Both mortar and bricks are modeled independently in tension
and compression, through different isotropic damage variables and activation criteria. Reference is made
to a masonry pillar, constituted by three Italian standard bricks interspersed by two mortar joints, reinforced
by a perfectly-adherent FRP external sheet. The overall response and the collapse mechanism are
investigated, induced by different boundary conditions and mechanical properties of constituent materials.
Numerical predictions are compared to those provided by the Italian design code, with the aim of
assessing pros and cons of simplified formulae. As a valid alternative for practitioners, the recourse to
a numerical database is proposed, generated by combining FE predictions and best fitting, suitable to
specify closed-form interface laws with brick and mortar compressive strengths as entries.
2010 Elsevier Ltd. All rights reserved
FE simulation of FRP-from-masonry delamination: three-dimensionaleffects and interface traction assessment
No full textDelamination of FRP-reinforced masonry is a complex phenomenon, which, in principle, may involve both the adhesive joint and the masonry. When recourse in made to highly resistant adhesives of recent conceiving, the quasi-brittle response of the heterogeneous support is expected to play the major role. At a structural level, delamination response can be described effectively also by concentrating all the sources of dissipation and non-linearity at the masonry-FRP interface, and by assuming the support to behave linearly elastically. In this paper, a detailed and critical comparison between two different fully three-dimensional Finite Element models is developed: a first model in which only the masonry is damageable whilst the FRP reinforcement adheres perfectly to the support, whereas in the second model a zero-thickness, cohesive interface is located between the FRP and the support, whilst masonry behaves as a linear elastic material. The overall response during delamination and local traction distributions at the interface are critically investigated, varying the FRP reinforcement width
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