Search results for "material"
showing 10 items of 32550 documents
A specific operative protocol set up during the restoration of the Grammichele slate slab
2009
This work deals with the conservation of a slate slab, representing the map of Grammichele, a small town in the hinterland of South Eastern Sicily. The slab was engraved and painted in 1693, just after the tremendous earthquake that distroyed most of the towns in that area. The conservation process is illustrated through three steps: i) archive research; ii) physical chemical analysis of constitutive materials and degradation products; iii) planning and carrying out of the restoration and conservation operations.
Comportement en fatigue des composites en lin/époxy
2011
International audience; Le travail présenté s'intéresse à la caractérisation des propriétés mécaniques quasi-statiques et en fatigue d'un composite stratifié en lin/époxy. Les éprouvettes fabriquées par thermocompression ont des séquences d'empilement de 0/90° et ±45° pour les essais de traction uniaxiale et cisaillement plan respectivement. Les essais quasi-statiques révèlent une variabilité des propriétés mécaniques de l'ordre de 10%. Les essais de fatigue en traction et en cisaillement plan ont été réalisés pour des niveaux de contraintes compris entre 40 et 80% des valeurs ultimes du composite (US). L'étude des boucles d'hystérésis a mis en évidence une plastification plus importante en…
Straw as a contemporary biomaterial: energetic efficiency and enviromental sustanaibility
2016
Questo studio ha lo scopo di segnalare ricerche e applicazioni in ambito costruttivo europeo e non solo della paglia, con particolare attenzione all'efficienza energetica e al comfort abitativo. Il riciclo e riutilizzo dei materiali naturali sono gli obiettivi principali nella scelta di paglia come materiale da costruzione, consentendo di adottare un approccio metodologico complessivo, che potrebbe prendere in considerazione l'intero edificio del ciclo di vita. Partendo dalla storia dell'utilizzo di paglia nella costruzione edilizia, saranno riportati molti esempi di edifici che utilizzano tale materiale all'interno del loro involucro e struttura. Le caratteristiche principali della paglia …
Inconsistencies in the pozzolanic strength activity index (SAI) for silica fume according to EN and ASTM
2014
Published version of an article in the journal: Materials and Structures. Also available from the publisher at: http://dx.doi.org/10.1617/s11527-014-0457-6 Open Access New supplementary cementitious materials claimed to possess pozzolan properties emerge frequently. This development is driven both by economic and environmental pressures. Properties of new materials are compared with those of materials already well known, such as silica fume. Several test methods are standardized for making such comparisons, regulated by both European (EN) and American (ASTM) standards. Standardization indicates that procedures are secured to make comparisons valid and informative. In this article the sensit…
The effect of defect location on coating fragmentation patterns under biaxial tension
2005
Fragmentation of a coating possessing orthogonal preferential crack propagation directions is modeled for equibiaxial tensile loading. Two plausible cracking scenarios are compared, caused by flaws randomly distributed over the area of the coating or along the coating fragment edges. The two fragmentation scenarios considered are shown to yield qualitatively different fragment patterns.
Influence of the Resin Layer Thickness at the Interface of Hybrid Metal-composite Co-cured Joints
2011
As discussed in literature, the accurate analysis of the modern co-cured joints between composite materials or between a metal and a composite material (hybrid joints) is complicated by the influence of the interface resin layer on the interface singular stress field. In such joints, in fact, there is not a proper adhesive layer and the thickness of the resin layer, that plays the role of the adhesive, is not constant due to the presence of the reinforcing fibers in the composite adherent. For this reason several authors assume that a generic co-cured joint can not be studied as a simple bi-material joint, without considering the particular characteristics of the actual resin layer. This pr…
Experimental Investigation on Stiffness and Strength of Single-Lap Z-Pinned Joints in a Laminated CFRP Stress-Ribbon Strip
2016
Carbon fiber-reinforced polymer (carbon-polymer) is an advanced lightweight composite material with high strength and excellent resistance to corrosion and fatigue. Over the past decades, application of fiber-reinforced polymers has been spread from the aerospace to other branches of industry such as automobile and civil engineering. Unidirectional carbon-polymers have a high potential for replacing steel in tensile members. Recently, the first carbonpolymer stress-ribbon bridge has been constructed in Germany. The non-laminated strip-loop carbon-polymer thin strips were used as the load bearing components in this bridge. In comparison with the laminated components, the applied cables are c…
Characterization of rhenium oxide films and their application to liquid crystal cells
2009
Rhenium trioxide exhibits high electronic conductivity, while its open cubic crystal structure allows an appreciable hydrogen intercalation, generating disordered solid phases, with protonic conductivity. Rhenium oxide thin films have been obtained by thermal evaporation of ReO3 powders on different substrates, maintained at different temperatures, and also by reactive magnetron sputtering of a Re metallic target. A comparative investigation has been carried out on these films, by using micro-Raman spectroscopy and x-ray diffraction. Two basic types of solid phases appear to grow in the films: a red metallic HxReO3 compound, with distorted perovskite structures, like in the bulk material, a…
Etäoppimateriaalin rakenteistaminen
1997
Crystal structure and Hirshfeld surface analysis of [N(CH3)4][2,2′-Fe(1,7-closo-C2B9H11)2]
2017
Abstract This work investigates the meta -ferrabis(dicarbollide) anion that was isolated as salt of tetramethylammonium. The structure of the obtained crystal consisted of discrete [2,2′-Fe(1,7- closo -C 2 B 9 H 11 ) 2 ] − anions and disordered [N(CH 3 ) 4 ] + cations. The anion had a considerable chemical stability ensured by ionic and Van der Waals interactions. Thus, Hirshfeld surfaces and fingerprint plot were used to visualize, explore, and quantify intermolecular interactions in the crystal lattice of the title compound. This investigation proved that close contacts were dominated by H⋯H interactions.