Search results for "STIR"
showing 10 items of 426 documents
Direct numerical simulations of creeping to early turbulent flow in unbaffled and baffled stirred tanks
2018
Abstract It has been known for a long time that the fluid flow and several global quantities, such as the power and pumping numbers, are about the same in baffled and unbaffled mechanically stirred vessels at low Reynolds numbers, but bifurcate at some intermediate Re and take drastically different values in fully turbulent flow. However, several details are not yet completely understood, notably concerning the relation of this bifurcation with the flow features and the transition to turbulence. In order to shed light on these issues, computational fluid dynamics was employed to predict the flow field in two vessels stirred by a six-bladed Rushton turbine at Reynolds numbers from 0.2 to 600…
La rappresentazione della natura tra ornamento e narrazione. Il bestiario di Roma tra i secoli XI e XII
2012
International audience
‘Strong and courageous’ but ‘constantly insecure’: dialogical self theory, intersecting identities, and Christian mixed martial arts
2021
Being a mixed martial arts fighter and a devout Christian seems to present an apparent contradiction that requires identity work to bring these identities into unity. We used Dialogical Self Theory and explored the autobiography of Ron ‘H2O’ Waterman, a professional fighter turned evangelist, to understand how the tensions between the different identities or I-positions were negotiated. We identified two I-positions, ‘Ron the Fighter’ and ‘Ron the Pater Familias’, which related differently to religion, sport, and masculinity. Importantly, the negotiations were not between MMA and faith, but between these two I-positions that served the different needs for self-enhancement and union with som…
Welding abilities of UFG metals
2018
Ultrafine Grained (UFG) metals are characterized by an average grain size of <1 μm and mostly high angle grain boundaries. These materials exhibit exceptional improvements in strength, superplastic behaviour and in some cases enhanced biocompatibility. UFG metals barstock can be fabricated effectively by means of Severe Plastic Deformation (SPD) methods. However, the obtained welded joints with similar properties to the base of UFG material are crucial for the production of finished engineering components. Conventional welding methods based on local melting of the joined edges cannot be used due to the UFG microstructure degradation caused by the heat occurrence in the heat affected zone…
A continuum based fem model for friction stir welding—model development
2006
Although friction stir welding (FSW) has been successfully used to join materials that are difficult-to-weld or unweldeable by fusion welding methods, it is still in its early development stage and, therefore, a scientific knowledge based predictive model is of significant help for thorough understanding of FSW process. In this paper, a continuum based FEM model for friction stir welding process is proposed, that is 3D Lagrangian implicit, coupled, rigid-viscoplastic. This model is calibrated by comparing with experimental results of force and temperature distribution, then is used to investigate the distribution of temperature and strain in heat affect zone and the weld nugget. The model c…
Design of the friction stir welding tool using the continuum based FEM model
2006
In friction stir welding (FSW), the welding tool geometry plays a fundamental role in obtaining desirable microstructures in the weld and the heat-affected zones, and consequently improving strength and fatigue resistance of the joint. In this paper, a FSW process with varying pin geometries (cylindrical and conical) and advancing speeds is numerically modeled, and a thermo-mechanically coupled, rigid-viscoplastic, fully 3D FEM analysis able to predict the process variables as well as the material flow pattern and the grain size in the welded joints is performed. The obtained results allow finding optimal tool geometry and advancing speed for improving nugget integrity of aluminum alloys.
Friction Stir Knead Welding of steel aluminium butt joints
2008
To develop steel aluminium-tailored hybrids in a butt joint for sheets in a thickness of about 1 mm conventional Friction Stir Welding is not feasible due to a high distortion of the welded specimen. Contrary to Friction Stir Welding the tool used for Friction Stir Knead Welding has no pin wherefore higher welding speeds can be realised. Due to the fact that this is a newer process, applied for patent in 2005, the cut contours of the edges and their variations have to be optimised by numerical analysis to transfer a maximum of load in order to improve the formability. The examined materials in this paper are steel DC04, as well as the aluminium alloys AA5182 and AA6016 in sheet thicknesses …
Compressive behavior of short high-strength concrete columns
2010
Abstract The focus of the present paper is the compressive response of short high strength reinforced concrete members. Members have square transverse cross-sections and they are reinforced with longitudinal steel bars and transverse stirrups. A preliminary analysis to check the stability condition of longitudinal bars was made to verify that buckling occurs after yielding in compression. Prescriptions on required diameter and spacing of stirrups are given. In the following, a model is presented which allows us to evaluate the confinement pressures exercised by transverse steel and by longitudinal bars during the loading process taking into account the interaction of the stirrups with the i…
L’erotisme a les Cartes a les Senyores dels Àngels i de Jerusalem, de Francesc Fontanella
2014
Resum: Aquest article se centra en l'estudi del tractament de l'erotisme en algunes de les composicions pòetiques de Francesc Fontanella (1622-1682/3). El treball estudia quinze epístoles literàries que l'autor va dedicar a les monges dels convents dels Àngels i de Jerusalem de Barcelona durant la dècada de 1640. Es divideix en dues parts; a la primera s'identifiquen les composicions objecte d'estudi, es presenten breument i s'aclareixen alguns problemes relacionats amb la seva transmissió. A la segona s'analitzen detalladament totes les referències eròtiques presents als textos. Aquesta anàlisi, d'una banda, permet presentar una interpretació del sentit argumental del conjunt epistolar. D…
An analysis of through-thickness residual stresses in aluminium FSW butt joints
2006
Abstract In the paper, the results of a wide experimental campaign on friction stir welding (FSW) of aluminum alloys are reported. The attention was focused on the through-thickness residual stresses that occur on aluminum joints, after the welding process. In detail, using the hole-drilling method the residual stresses distribution in the zone close to the tool shoulder border of the joint advancing side, has been investigated; four different aluminum alloys and three different process conditions have been considered. The experimental analysis has shown that unlike traditional welding processes, the residual stresses are negative in the surface of the examined zone, and increase with depth…