Search results for "STIR"

Meshless Simulation of Friction Stir Welding

2007

This paper encompasses our first efforts towards the numerical simulation of friction stir welding by employing a Lagrangian approach. To this end, we have employed a meshless method, namely the Natural Element Method (NEM). Friction Stir welding is a welding process where the union between the work pieces is achieved through the extremely high deformation imposed by a rotating pin, which moves between the two pieces. This extremely high strain is the main responsible of the difficulties associated with the numerical simulation of this forming process. Eulerian and Arbitrary Lagrangian-Eulerian (ALE) frameworks encounter difficulties in some aspects of the simulation. For instance, these ap…

Effect of additives on process stability of mesophilic anaerobic monodigestion of pig slaughterhouse waste

2012

The effect of two additives on anaerobic monodigestion of pig slaughterhouse waste was studied in three laboratory scale continuously stirred tank reactors (CSTRs) operated for 242-284 days at 35°C. A higher organic loading rate (OLR), namely 2.25 kg volatile solids (VS)/m(3)d with a hydraulic retention time (HRT) of 30 d was feasible with an additive containing Fe, HCl and trace elements while an OLR of 1.5 kg VS/m(3)d (HRT 30 d) led to instabilities in CSTR with an additive consisting of Fe and HCl and in CSTR without additives. Methane yields of ca. 700 dm(3) CH(4)/kg VS(fed) were obtained in all reactors under stable conditions. Both additives decreased H(2)S concentration of the biogas…

Työn antropologia ja Karl Marx

2012

Työ tai sen puute puhuttaa ihmisiä. Miksi ylipäänsä pitäisi käydä töissä? Todennäköinen vastaus on, että töissä pitää käydä perustarpeiden tyydyttämiseen tarvittavan palkan vuoksi. Samalla työtä pidetään pakonomaisena raatamisena; pelkkänä keinona joidenkin päämäärien saavuttamiseksi. Se on epämiellyttävää ja siitä haluttaisiin päästä eroon, jos se suinkin olisi mahdollista. Karl Marx kirjoitti työstä kapitalistisen tuotantotavan puitteissa. Hänen analyysinsa työn käsitteestä antoi ehkä ensimmäisen modernin käsityksen työn roolista ihmiselämässä. Se myös sisälsi edellä kuvatun ristiriidan: työ on välttämätöntä, mutta samalla siitä toivotaan päästävän eroon. Mitä tämä ristiriita kertoo ihmis…

SIMULAZIONI CFD DEL CAMPO DI MOTO A BASSO NUMERO DI REYNOLDS IN BIOREATTORI AGITATI CON E SENZA SETTI FRANGIVORTICE

2016

I recipienti meccanicamente agitati sono apparecchiature frequenti dell’industria chimica di processo. Questi sono tipicamente dotati di setti frangivortice (recipienti baffled) atti a rompere il moto prettamente tangenziale tipico dei recipienti sprovvisti di setti (recipienti unbaffled) e convertirlo in moto assiale e radiale. La presenza dei setti evita inoltre nella zona centrale del sistema la formazione del vortice d’aria che può talvolta essere indesiderato o in taluni casi creare instabilità una volta arrivato alla girante. I recipienti unbaffled sono considerati quindi dei miscelatori meno efficienti rispetto a quelli provvisti di setti. Tali sistemi sono pertanto ad oggi impiegati…

Evaluation of Residual Stresses During Fatigue Test in an FSW Joint

2008

At present, friction stir welding (FSW) represents one of the most interesting techniques in the field of welding. The process is has been implemented in industrial practice for joining aluminium alloys, while the welding of the titanium alloy and the steels is still primarily in a developmental stage.

Työn ja perheen välisten ristiriitojen yhteydet hyvinvointiin

2005

[Cèdula. 1692. 08. 12]

1731

Inclou també la Cèdula reial de 29 d'Abril de 1731 amb el nomenament de Don Manuel de Riovello Franco com a "Juez Conservador y Privativo" i dues cèdules anteriors, de 12 d'Agost de 1692 i de 10 de Setembre de 1697 Caplletra grav. Sign.: A-D2 Reclams

Experimental Comparison of the MIG and Friction Stir Welding Processes for AA 6005 Aluminium Alloy

2015

In this study, the mechanical properties of welded joints of AA 6005 aluminum alloy obtained with friction stir welding (FSW) and conventional metal inert gas welding (MIG) are studied. FSW welds were carried out on a semi-automatic milling machine. The performance of FSW and MIG welded joints were identified using tensile and bending impact tests, as far as the environmental aspects are also included in the discussion. The joints obtained with FSW and MIG processes were also investigated in their microstructure. The results indicate that, the microstructure of the friction stir weld is different from that of MIG welded joint. The weld nugget consists of small grains in FSW than those found…

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.

On vortex shape in unbaffled stirred vessels as measured by digital image analysis

2012

In this work, digital image analysis coupled with a suitable shadowgraphy-based technique is employed to investigate the shape of the free-surface vortex that forms in uncovered unbaffled tanks stirred by either a D=T/3 Lightnin A310 or a D=T/3 Rushton turbine. The technique is based on back-lighting the vessel and suitably averaging vortex images over time. Data obtained show that the two different impellers give rise to quite different vortex shapes. A novel 2-parameter model is proposed that successfully describes vortex shapes obtained with both impellers.