1,720,967 research outputs found
Studio numerico dell'effetto della deformabilità sul comportamento di cuscinetti idrodinamici
No full textA numerical approach for static and dynamic analysis of deformable journal bearings
No full textThis paper presents a numerical approach for the static and dynamic analysis of hydrodynamic radial journal bearings. In the first part, the effect of shaft and housing deformability on pressure distribution within oil film is investigated. An iterative algorithm that couples Reynolds equation with a plane finite elements (FE) structural model is solved. Viscosity-to-pressure dependency (Vogel-Barus equation) is also included. The deformed lubrication gap and the overall stress state are obtained. Numerical results are presented with reference to a typical journal bearing configuration at two different inlet oil temperatures. Obtained results show the great influence of bearing components structural deformation on oil pressure distribution, compared with results for ideally rigid components. In the second part, a numerical approach based on perturbation method is used to compute stiffness and damping matrices, which characterize the journal bearing dynamic behavior
Harmonic model for numerical simulation of thermal stresses in work roll of hot rolling mill
No full text
Thermo-mechanical analysis of a copper mould for continuous casting of steel
No full textThis work deals with the thermo-mechanical analysis of a copper mould, which is a component that controls initial solidification in continuous steel casting. Large temperature gradients, caused by a huge thermal flux imposed by steel, are responsible for high stresses and plastic strains. Plant switch-off also induces residual stresses which may increase with repeated thermal cycling over a casting sequence. Furthermore, oscillations of the melt metal level determine a fluctuation of the temperature peak on the surface of the mould. As a result, thermal fatigue cracks tend to develop on the mould inner surface, especially for increased productivity rates characterized by higher casting speed and thermal flux. This work aims to study the mechanical behaviour of the mould and to propose a simplified approach to relate stress-strain cycles to the component fatigue life. A thermo-mechanical analysis is performed by a finite element elasto-plastic model, supported by simplified analytical models useful to interpret results. Experimental static strength data are used to calibrate the elasto-plastic material model in FE simulations, as well as to estimate the strain based fatigue curve with the so-called Universal Slopes Equation. The component service life is finally estimated as the number of either fatigue cycles or casting sequences
Strategie numeriche “industry-oriented” per la progettazione termo-meccanica di componenti per impianti siderurgici
No full textQuesto lavoro descrive alcune strategie numeriche per affrontare problematiche tipiche della progettazione termo-meccanica di componenti per l’industria siderurgica. Sebbene le analisi debbano includere fenomeni complessi come plasticità a differenti temperature, fatica termica, transizione di fase, è necessario che i modelli implementati soddisfino anche i requisiti industriali legati alla rapidità di calcolo e alla possibilità di ottenere risultati accurati senza far ricorso a formulazioni complesse o a onerose prove sperimentali. Si affronterà il calcolo termico di un componente che, lavorando a contatto con metallo ad elevata temperatura, incorre in parziale fusione. Verrà poi presentata una metodologia basata su elementi finiti di tipo armonico per lo studio delle sollecitazioni su rulli di laminazione. Infine si discuterà la metodologia di scelta dei modelli di plasticità ciclica da utilizzarsi per l’analisi numerica di una lingottiera per colata continua
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