Search results for " sandwich"

EXPERIMENTAL AND NUMERICAL EVALUATION OF THE MECHANICAL BEHAVIOUR OF GFRP SANDWICH PANELS

2007

This work deals with the analysis of the mechanical behaviour of a class of sandwich structures widely employed in marine constructions, constituted by fiber-glass laminate skins over PVC foam or polyester mat cores. In detail, a systematic experimental study and numerical simulations have shown that the theoretical prediction of the strength and the actual failure mechanism of these sandwich structures can be affected by significant errors, specially in the presence of prevalent shear loading. Moreover, because of the low shear stiffness and the elastic constants mismatch of the skins and core material, failure modes and strength are strongly influenced by eventual stresses orthogonal to t…

Inferential tools in penalized logistic regression for small and sparse data: A comparative study.

2016

This paper focuses on inferential tools in the logistic regression model fitted by the Firth penalized likelihood. In this context, the Likelihood Ratio statistic is often reported to be the preferred choice as compared to the ‘traditional’ Wald statistic. In this work, we consider and discuss a wider range of test statistics, including the robust Wald, the Score, and the recently proposed Gradient statistic. We compare all these asymptotically equivalent statistics in terms of interval estimation and hypothesis testing via simulation experiments and analyses of two real datasets. We find out that the Likelihood Ratio statistic does not appear the best inferential device in the Firth penal…

Forming of aluminum foam sandwich panels: Numerical simulations and experimental tests

2006

Abstract The forming of the completed aluminium foam sandwich (AFS) panels would determine an improvement in the manufacturing of parts and panels. In this paper the authors have investigated the formability of AFS through experiments and numerical simulations. As far as the former are concerned, commercially prepared panels have been considered and bending and stamping processes have been taken into account. In addition, FEM analyses have been developed, utilizing a porous material model following the evolution of the material density throughout the forming processes.

Stability of solution for Rao-Nakra sandwich beam model with Kelvin-Voigt damping and time delay

2022

This paper deals with stability of solution for a one-dimensional model of Rao?Nakra sandwich beam with Kelvin?Voigt damping and time delay given by ??1?1?????? ? ??1?1?????? ? ??(??? + ?? + ??????) ? ?????????? ? ??????????( ? , ?? ? ??) = 0, ??3?3?????? ? ??3?3?????? + ??(??? + ?? + ??????) ? ?????????? = 0, ????????? + ?????????????? ? ????(??? + ?? + ??????)?? ? ?????????? = 0. A sandwich beam is an engineering model that consists of three layers: two stiff outer layers, bottom and top faces, and a more compliant inner layer called ?core layer?. Rao?Nakra system consists of three layers and the assumption is that there is no slip at the interface between contacts. The top and bottom lay…

Investigation on the behaviour of fully thermoplastic composite sandwich beams under concentrated loads

2009

The recent development of new low cost manufacturing processes adopting thermoplastic matrices in the production of structural long fibre reinforced laminates is fostering an increasing interest towards this class of materials. The automotive sector in particular is attracted by the high energy absorbing, damage tolerance performances and manufacturing and recycling potentials of structural thermoplastic composites. In this study a number of fully thermoplastic sandwich beams have been manufactured in order to investigate flexural and shear rigidity performances as well as the indentation behavior under static concentrated loads.

Induced smoothing in LASSO regression

The thesis is being carried out with the National research Council at the Institute of Biomedicine and Molecular Immunology "Alberto Monroy" of Palermo, where I am a fellow, under the supervision of MD Stefania La Grutta. Our research unit is focused on clinical research in allergic respiratory problems in children. In particular, we are interested in to assess the determinants of impaired lung function in a sample of outpatient asthmatic children aged between 5 and 17 years enrolled from 2011 to 2017. Our dataset is composed by n = 529 children and several covariates regarding host and environmental factors. This thesis focuses on hypothesis testing in lasso regression, when one is interes…

On the Finite Element Simulation of Secondary Operations on Metallic Foams

2007

Metallic foams have been recently introduced also as industrial materials due to their well known advantages. In fact, their low mass in conjunction with the good thermal and mechanical properties push toward an extensive diffusion in manufacturing industry. In the study here addressed, a very accurate investigation concerning the latter two aspects has been carried out. In fact, a secondary manufacturing process, i.e. the foam bending, has been taken into account. Anyway, all the knowledge derived for sheet metal bending is not directly applicable to the foams. A finite element code has been utilized for modeling the foam behavior during the bending processes and an accurate material rheol…

The ALICE Transition Radiation Detector: Construction, operation, and performance

2018

The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/$c$ in p-Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both …

“L’incendio di borgo” - Between heavy and meaningful burdens

2009

Mechanical Behaviour of a Green Sandwich Made of Flax Reinforced Polymer Facings and Cork Core

2015

Abstract This work investigates the flexural behavior of a composite sandwich made of flax fibers reinforced skin facings and an agglomerated cork core, to be employed as an eco-friendly solution for the making of structural components of small sailing boats. An experimental mechanical characterization of the strength and stiffness flexural behavior of the proposed sandwich is carried out, providing a comparison of performances from three implemented assembling techniques: hand-lay-up, vacuum bagging and resin infusion. Sandwich beams have been tested under three point bending (TPB) at various span lengths. A procedure is also proposed and implemented to consider the potential influence of …