Search results for " sand"

UNA PROCEDURA AUTOMATIZZATA PER LA DETERMINAZIONE DELLE CARATTERISTICHE MICROSTRUTTURALI DELLE SABBIE MEDIANTE ANALISI DI IMMAGINI DI SEZIONI SOTTILI

2012

È ben noto che il comportamento meccanico microscopico delle sabbie - e in generale dei terreni granulari - trae origine dalle loro caratteristiche microstrutturali, quali, per esempio, il numero di coordinazione dei singoli grani, l’indice di contatto intergranulare (grain contact ratio) e l’indice di addensamento dei grani (packing density index). Appare, quindi, di notevole importanza la determinazione degli indici predetti con alto grado di affidabilità e di ripetibilità. Lo studio dell’assetto dei contatti intergranulari e il calcolo degli indici che lo caratterizzano, viene condotta comunemente su immagini piane dell’insieme di grani mediante esame visuale e restituzione grafica assis…

Unsaturated sand in the stability of the cuesta of the Temple of Hera (Agrigento)

2013

In the Valle dei Templi in Agrigento seven Doric temples stand lengthwise the crest of a rigid calcarenite cuesta over a layer of carbonate sand which lies along a thick stratum of clays. The environment is highly prone to landslides since topplings of calcarenite blocks often occur. The rock slopes are moving back and the slope edge draw near to the foundation of the Temple of Hera Lacinia contributing to increase their perilous condition. To assess the role of unsaturated sands in the instability processes, after the compositional and textural analysis of the material, direct shear tests and oedometer tests have been carried out on sand samples initially at the natural state, with low or …

The Southeast Asian Lady {Boy}

2021

Singapore, una città-stato dal carattere decisamente cosmopolita, proietta nel mondo un'immagine urbana di frizzante modernità, ricchezza e benessere. All'ombra di potenti landmark architettonici e ai margini di una società opulenta, si nascondono però le condizioni di povertà ed esclusione in cui vive una buona metà della popolazione. Il vero ritratto di Singapore è quindi inciso da una profonda frattura, acuita dalla multietnicità della popolazione. Ed è nell'ambito di questi profondi contrasti, come talvolta può accadere nelle situazioni più estreme, che avvengono straordinari miracoli. Ed ecco che il miracolo è stato compiuto dalla cucina! Nonostante la città sia una delle più care al m…

ANALISI DEL COMPORTAMENTO MECCANICO DI SANDWICH ECO-COMPATIBILI RINFORZATI CON FIBRE NATURALI

2015

The increasing environmental sensitivity in many industrial fields, from automotive to aeronautics to naval field, has led to an increasing demand of new bio-materials or renewable structural materials. In order to give a contribution to the design of eco-compatible structural materials, in this work new sandwich materials constituted by a core made by balsa and skins made by a composite material made by a “green” epoxy reinforced by agave fibers extracted from striated and americana agave obtained in Sicily by a proper research program financed by European founds. Previous theoretical analysis followed by systematical experimental analysis of the core, of the skins and the of the sandwich,…

Analysys and optimization of an end double-lap bonded joint for GFRP composite sandwich panels

2022

Although the best configuration of the joints used to connect a common GFRP sandwich panel with the main structures is the adhesively bonded one, that permit high static and fatigue performances as well as to avoid stress concentrations, mechanical or hybrid joints are still widely used in the industrial field. After a preliminary theoretical design, the optimal configuration of an end adhesively bonded double-lap joint constituted by a simple insert as internal adherent and the same face sheets as external adherent, has been researched. In detail, several experimental tests and successive numerical simulations under tensile and bending loading, performed by varying the main influence para…

A New Thermal Theory for Thermo-Mechanical Analysis of Composites

2009

The use of laminated and sandwich construction to achieve multi-functional objectives within a single structure continues to increase. It is especially desirable to use laminated construction in structures exposed to thermal loading, where heat resistant coating materials may be bonded to traditional structural materials. Design of such structures requires an accurate analysis of stresses induced by thermal as well as mechanical loads. A novel laminated plate theory and 3D finite element model based on first-order zig-zag sublaminate approximations are presented for thermal stress analysis of composite laminates and sandwich plates. The finite element is developed with the topology of an ei…

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.

OTTIMIZZAZIONE DI UNA GIUNZIONE INCOLLATA A DOPPIA SOVRAPPOSIZIONE PER SANDWICH IN COMPOSITO

2016

Grazie alle peculiari performances meccaniche, quali soprattutto l’elevata resistenza a flessione unita ad un basso peso specifico, le strutture sandwich in composito sono sempre più frequentemente utilizzate nella moderna progettazione industriale. Nel presente lavoro, considerando un composito sandwich con skins in vetroresina e core in PVC espanso, è stato eseguito uno studio numerico e sperimentale al fine di individuare la configurazione ottimale di una giunzione incollata a doppia sovrapposizione avente quali aderendi esterni le stesse skins del sandwich e aderendo interno costituito da un inserto in metallo o in composito. In dettaglio, previa preliminare ottimizzazione teorica della…

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

2009

Coupling a hydro-maritime model and remotely sensed techniques to assess the shoreline positioning uncertainty: the Marsala coast study case

2010

The severe erosion phenomena affecting the Mediterranean coasts are strictly related to geophysical characteristics and socio-economic pressures. This suggests the need of monitoring and modelling the phenomenon in order to quantify its strength. In fact, the shoreline position, as well as its temporal evolution, provides important information for designing defence structures and for the development of a coastal management plan. The shoreline has a dynamic nature as it changes both in the short and long period. Those changes are caused by geo-morphological (e.g. bars and barrier island development etc.) and hydrodynamic (wave motion, tides and flows) processes, as well as by sudden and fast…