Search results for "ductility"
showing 10 items of 71 documents
Stainless steel grids for confinement of clay brick masonry columns
2016
This work presents the results of an experimental investigation on the behavior of 21 solid clay brick columns internally strengthened by stainless steel grids placed in the horizontal joints of mortar. This reinforcing technique can be applied as a constructive technique for new construction or as a retrofitting technique for existing structures (old structures to be reconstructed by original constructive method and internal reinforcement). Monotonic compressive loading tests were carried out under concentric and eccentric load. The effects of different numbers of steel grids and eccentricity of the external load were examined. Also, a detailed characterization of the constituent materials…
Analytical stress-strain law of FRP confined masonry in compression: Literature review and design provisions
2017
Abstract The use of Fibre Reinforced Polymer (FRP) wraps has become common in practical applications to retrofit existing columns with poor structural features. Wrapping the member with one or more FRP sheets makes it possible to induce confinement action and enhance strength and ductility. This application has been widely studied and adopted in reinforced concrete members for about twenty years, while its suitability to masonry columns and piers has been investigated during the last decade. The results of several studies were summarized in different design expressions for calculating effective confinement pressure, ultimate compressive stress and strain, and the overall trend of the stress…
Friction stir welding of lap joints: Influence of process parameters on the metallurgical and mechanical properties
2009
Abstract Aluminum alloys are widely used in the aircraft industries even if such materials present lower ductility with respect to steels, anisotropy phenomena and, more important, they are often “difficult” to be welded or even “non-weldable”. In the last years the friction stir welding process (FSW) was proposed and applied in order to get good mechanical and technological performances of the joints. In this paper, an experimental and numerical investigation on the lap joining of AA2198-T4 aluminum alloy blanks by FSW is presented. In particular the joints strength and metallurgical properties are investigated by varying the joint configuration and the tool geometry and rotational speed. …
Effect of graphene and fabrication technique on the release kinetics of carvacrol from polylactic acid
2019
Abstract Porous membranes and thin films containing poly-lactic acid (PLA), carvacrol (CRV) and graphene nanoplatelets (GNP) were fabricated by electrospinning and solvent casting at different formulations. The systems were characterized from a mechanical, morphological, calorimetric and spectroscopic point of view. CRV release as a function of time was studied and a mathematical model was used to fit and interpret the data in order to investigate the release mechanism. The results indicate that the incorporation of GNP generally determined a simultaneous strengthening, stiffening and toughening effect, while preserving a good ductility. Furthermore, integrating GNP allowed tuning the amoun…
Processing conditions, microstructure and mechanical properties of hetero-nanostructured ODS FeAl alloys produced by spark plasma sintering
2013
International audience; Spark plasma sintering (SPS) has been used to sinter a milled oxide dispersion-strengthened (ODS) FeAl powder in order to prepare dense nanostructured parts. The effect of processing conditions including sintering temperature, holding time and degassing treatments on the microstructure and mechanical properties of the as-sintered materials was investigated. A hetero-nanostructure that contains nano, ultrafine and micrometric grains was confirmed to be developed whatever the processing window, due to the large temperature difference generated during the SPS process itself. The grain size distribution can be tailored by selecting a combination of sintering temperature …
Improving friction stir welding of blanks of different thicknesses
2007
Friction stir welding (FSW) appears to be a promising process even in the welding of blanks of different thicknesses. Actually, such particular tailor welded blanks (TWBs) are usually characterized by a reduction in ductility due to the utilized fusion welding process. In this paper the authors, starting from a preliminary feasibility study, investigate the possibility to improve the mechanical performances of friction stir welded blanks of aluminum alloy with different thicknesses. Both experiments and a FE analyses are developed for a few case studies with different thickness ratios between the blanks. The numerical investigations are performed with the aim to highlight the material tempe…
Formability of Friction Stir Welded AZ31 Magnesium Alloy Sheets
2010
The formability of friction stir welded AZ31 magnesium alloy sheets was investigated by means of uniaxial tensile and hemispherical punch tests performed under different process conditions. The results of the tensile tests were analysed in terms of flow stress and ductility at different temperature and strain rate; the hemispherical punch tests, carried out at different temperatures, provided the limiting dome height. The formability of FSW-ed blanks was compared to the one exhibited by the base material in order to evaluate the quality of the welded joints.
Tool Geometry in Friction Stir Welding of Magnesium Alloy Sheets
2009
Friction Stir Welding (FSW) has been arousing a continuously increasing interest among joining processes since its invention in 1991. Although mainly used for aluminum alloys, it can also be applied to other light alloys. In the present work, experimental and numerical campaigns have been performed with the aim to study the effect of the tool geometry on the mechanical properties of FSW-ed AZ31 magnesium alloy sheets. The results, presented in terms of tensile strength, ductility, micro-hardness values and numerical field variables distributions, allow to reach a deeper knowledge on the behaviour of such relatively new material when FSW-ed, and can be used for a full optimization of the joi…
Early-stage detection of surface stress corrosion cracking at the subgranular level
2014
The strain field at the interface between an alloy and its oxide layer has been mapped using nanopatterned gauges resistant to the environment of the primary nuclear medium. It was found that oxidation has decreased the alloy ductility, thereby enabling some grain boundary opening to be detectable from 1.8 % strain. It is shown that statistics of extreme rare events of hotspots quantify the occurrence of the local opening of intergranular cracks, and thereby the ageing process.
Effect of the processing techniques on the properties of ecocomposites based on vegetable oil-derived Mater-Bi® and wood flour
2009
Polymer composites based on biodegradable polymers and natural-organic fillers are becoming more and more important because of their interesting properties in terms of environmental impact, manufacturing cost, and esthetic features. In particular, the use of biodegradable polymer matrices allows obtaining a full biodegradability. One of the most interesting biodegradable polymer families is the Mater-Bi® one. In this work, we investigated the processability, the influence of different processing techniques, and the influence of the filler particle size on the properties of Mater-Bi/wood flour composites. Injection molding caused a partial degradation of the macromolecular chains, whereas si…