Browsing by Keyword "Dynamic"
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Item Disaggregation process for dynamic multidimensional heat flux in building simulation(2017-08-01) Garay, Roberto; Riverola, Alberto; Chemisana, Daniel; Martinez, Roberto Garay; Tecnalia Research & InnovationHeat transfer across envelopes (façade, roof, glazed areas) represents a big share of the energy flow within the heat balance of buildings. This paper focuses on areas of the envelope where multi-dimensional heat transfer occurs. These areas are commonly defined as thermal bridges, due to a localized reduction of thermal resistance of constructions in these places. This paper reviews common standardized methods to assess heat transfer in buildings, under various modelling assumptions: one-dimensional, multi-dimensional, steady state and dynamic. Within presently developed modelling and assessment methods, a need for improvement has been identified over existing methods for the thermal assessment of multi-dimensional heat transfer under dynamic conditions. A phasorial approach to differential heat transfer in thermal bridges has been developed, which serves as the dynamic extension of steady-state thermal bridge coefficients. This formulation is applied to the junction of a masonry wall with a concrete slab.Item Initiation of Dynamic Recrystallization of As-Cast N08028 Alloy(PoPuPS (University of LiFge Library), 2021) Hurtado, Iñaki; Mendiguren, Joseba; Poletti, Cecilia; Silveira, Elena; Navarro, Aitor; Mora, Elena; Caracterización y Validación. MaterialesThe use of high nickel content austenitic stainless steels (SASS) has significantly increased in the last decade. The corrosion and high fatigue resistance of these materials make them suitable for manufacturing oil country tubular goods (OCTG). SASS are processing by forging from casting conditions. Dynamic recovery (DRV) and recrystallization (DRX) of as-cast super austenitic stainless steel, N08028 Alloy, is investigated to study the refining effect from the as-cast grain structure to fully recrystallized austenite due to hot deformation. Both the critical stress and strain for the initiation of DRX are determined using the flow curves. To perform this analysis, hot compression tests are performed at temperatures between 900°C and 1250°C, and strain rates between 0.1 s-1 and 10 s-1, up to 0,8 final strain using a Gleeble®3800 thermomechanical simulator. Subsequently, the Johnson-Avrami-Mehl-Kolmogorow (JMAK) model is used to numerically fit the flow curves and consequently determine the critical strain. No critical points are seen for temperatures under 1100°C. Above this temperature, the JMAK model proves to be valid in all studied strain rates.Item Thin-Wall Machining of Light Alloys: A Review of Models and Industrial Approaches: A review of models and industrial approaches(2019-06-01) Del Sol, Irene; Rivero, Asuncion; López de Lacalle, Luis Norberto; Gamez, Antonio Juan; SGThin-wall parts are common in the aeronautical sector. However, their machining presents serious challenges such as vibrations and part deflections. To deal with these challenges, different approaches have been followed in recent years. This work presents the state of the art of thin-wall light-alloy machining, analyzing the problems related to each type of thin-wall parts, exposing the causes of both instability and deformation through analytical models, summarizing the computational techniques used, and presenting the solutions proposed by different authors from an industrial point of view. Finally, some further research lines are proposed.