Search results for "LFW"
showing 10 items of 15 documents
Nitrogen broadening of SF6 transitions in the nu3 band
2001
Abstract Nitrogen induced pressure-broadened halfwidths of a number of ν3 transitions of SF6 are calculated using the complex Robert–Bonamy (CRB) formalism. The calculations are made at 200, 250, 296 and 350 K and the temperature dependence of the halfwidths are determined. The intermolecular potential is taken as a sum of the leading electrostatic and Lennard-Jones [6] , [7] , [8] , [9] , [10] , [11] , [12] atom–atom components. The dynamics of the collision process are correct to second order in time. The calculated halfwidths are used to simulate the ν3 spectrum, which is compared to a simulation made using the HITRAN96 halfwidths and measurements made at the Universite Pierre et Marie C…
An Illustration to Ælfric’s De temporibus anni in Ælfwine’s Prayerbook
2020
L'articolo esamina un diagramma contenuto nel manoscritto London, British Library, Cotton Titus D.xxvii+xxvi, generalmente noto come 'Ælfwine’s Prayerbook'. Il diagramma, che si trova al fol. 21 v , è stato in genere interpretato come una rota incompleta, o delle maree o dei venti (dal momento che contiene solo 4 dei canonici 12 venti della tradizione scientifica medievale). Una analisi comparativa e dettagliata delle caratteristiche del diagramma, tuttavia, mostra come l'ipotesi della rota delle maree sia da rigettare in favore della teoria di una rota ventorum. Inoltre, l'analisi dei testi contenuti nel manoscritto rivela una stretta connessione tra il diagramma e il De temporibus anni di…
Experimental and Numerical Analysis of Microstructure Evolution during Linear Friction Welding of Ti6Al4V
2015
Abstract Linear Friction Welding (LFW) is a solid state welding process used to joint bulk components. In the paper, an experimental and numerical study on LFW of Ti6Al4V titanium alloy is presented. A laboratory designed LFW machine has been used to weld the specimens with different contact pressure and oscillation frequency. The joint microstructure has been experimentally observed with SEM and EDS. A dedicated numerical model, able to predict temperature, strain and strain rate distribution as well as the phase volume fraction evolution, has been utilized to predict the final microstructure in the welded parts. It was found that complete transformation of the alpha phase into beta phase …
Numerical modelling of the linear friction welding process
2010
Linear friction welding (LFW) is a solid-state joining process applied to non-axisymmetric components. LFW involves joining of materials through the relative reciprocating motion of two components under an axial force. In such process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and proper bonding conditions due to both the temperature increase and the local pressure of the two edges to be welded. In the present work the authors present a numerical model of the linear friction welding process of AISI 1045 parts. The numerical model allowed to highlight the process mechanics and the physical conditions which must be r…
On the fem simulation of FSW and LFW operations
2010
Friction based solid state welding processes
2012
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…
Trasmissioni per sistemi di propulsione ibrida e Linear Friction Welding
2017
Trasmissioni per sistemi di propulsione ibrida. In tale ambito presentano interessanti caratteristiche e prestazioni, le trasmissioni a variazione continua del rapporto di tipo Power Split (PS-CVTs). La progettazione di tali trasmissioni può essere molto insidiosa a causa della notevole numero di opzioni possibili e della complessità costruttiva. Una vasta letteratura, sia sperimentale che teorica, si è occupata dell'analisi, dell'ottimizzazione e del controllo, di specifiche soluzioni costruttive. Tuttavia la selezione del layout è fondamentale e qualunque scelta aprioristica, a volte dettata solo dalla pratica, potrebbe portare a soluzioni sub-ottimali, nonostante il tempo e le risorse im…