FRD - Investigación - Ciencia y Tecnología
Permanent URI for this communityhttp://48.217.138.120/handle/20.500.12272/1225
Browse
9 results
Search Results
Item Numerical model of UOE steel pipes: Forming processand structural behavior(ASOCIACIÓN ARGENTINA DE MECÁNICA COMPUTACIONAL AMCA, 2007) Raffo, Javier Leandro; Toscano, Rita; Mantovano, Luciano; Dvorkin, EduardoDeepwater pipelines are designed to withstand, without collapsing, the external pressureand bending imposed on them, either by the laying process or by the topology of the sea bottom. In previous publications CINI researchers have developed finite element models to predict collapse loadsand collapse propagation loads. Large diameter pipes for onshore and offshore applications are manufactured using the UOE process.The manufacturing process consists in the cold forming of heavy plates followed by welding and thenby an expansion. First the plate is pressed along its edges, formed into a U-shape and then pressedinto an O-shape between two semicircular dies. Afterwards the pipe is welded by SAW process andfinally is expanded. In this paper we develop a 2D finite element model to simulate the UOE process and the structuralbehavior of the formed pipes in external pressure collapse tests. Using the developed model we cananalyze the effects of the process parameters in each forming step on the final geometry and structuralproperties of the pipeItem Limitations due to the detector in the low coherence interferometry(2008-02-15) Morel, Eneas Nicolás; Torga, Jorge RománSe describirá como se generan las señales de interferometria de baja coherencia en el espacio de Fourier, se determinara las características que determinan el rango dinámico del sistema y las señales asociadas al sistema de detección y su influencia en la señal de interferencia.Item Characterization of reference standards for dirt by Laser Ablation Induced Photoacoustics (LAIP)(2009-07-23) Orzi, D.J.O; Morel, Eneas Nicolás; Torga, Jorge Román; Ravigioni, A.N.; Bilmes, G.MMeasurements of surface cleanliness and dirt characterization are important problems in a wide range of processes in industry and production. Standard methods are in most cases cumber some laboratory procedures that must be performed out of the production lines. Instruments and methods for clean liness determination and dirt characterization require reference standards for calibration. For that purpose we built a possible dirt reference standard (DRS) made by films of graphite greases ubjected to heat treatment for mechanical stabilization. The DRS characterization was performed by Laser Ablation Induced Photoacoustics (LAIP). The measurement of the thickness of the films was made by low-coherence interferometry.Item Simple method for thickness measurement in opaque samples with a Michelson-Sagnac interferometer(2008-04-24) Morel, Eneas Nicolás; Torga, Jorge RománWe present in this work a method to measure thicknesses of opaque samples. The technique combines the use of low coherence interferometry with a Michelson-Sagnac configuration. This ring set-up let us to measure both faces of the sample simultaneously. So it is possible to obtain the thickness by measuring the optical path difference between a reference and both surfaces of the sample. Experimental results up to 1mm are shown in metal gauge block. A resolution better than 10 micronswas obtained.Item Fast scanner with position monitor forlargeopticaldelays(2001-11-01) Constantino, Santiago; Martínez, Oscar; Torga, Jorge Román; Do Campo, P.; Libertiun, A.R.Wepresent a new fastscansystemthatemploys a stepper motor used in a single steposcillatingmode and a position monitor devicebasedon a diode laser. Thesetupusedgeneratesdelays as large as 105 ps at 10 Hz, with 100% dutycycle. Wealso introduce a reliabledevicebasedontheshadow of a movingcutterwith a laser diode as the light source to avoidpowerfluctuationsproblems.Item Wide band interferometryforthicknessmeasurement(2003) Constantino, Santiago; Martínez, Oscar; Torga, Jorge RománIn thisworkwepresentthe concept of wide band interferometry as opposed to white-light interferometry to introduce a thickness measurementmethodthatgainsprecisionwhenthebandwidthisreduced to anadequatecompromise in order to avoidthedistortionsarisingfromthe material dispersion. The use of thewidestpossible band is a well established dogma whenthehighestresolutionisdesired in distance measurementswithwhite-light interferometry. Wewill show thatthe dogma fallswhenthicknessmeasurementsmust be carriedoutdue to material dispersion. In factthe precise knowledge of thefrequencydependence of therefractiveindexisessentialforadequatethicknessretrievalfromthe opticalexperiments. Thedevicewepresentisalsouseful to obtainthegroup refractiveindexthatisnecessary to calculatetheabsolutethicknessvalue. As anexample, we show thespreading of a siliconeoilon a reference surface in real time.Item Molecular rotational diusion detected by dierential fluorescence energy(2000-03-01) Torga, Jorge Román; Marconi, Mario; Negri, Martin; Aramendia, PedroIn this paper, we present a complete study of the influence of the molecular rotational diffusion movement in the fluorescence signal when a sample is excited by two short pulses. The study includes the calculations of this effect for ellipsoidal molecules. Experimental results are presented that show a fluorescence behavior influenced by the molecular rotational diffusion movement with temporal characteristics that agree with our calculations.Item Simultaneous measurement of deformation and thickness change in polymer films(2006-08-14) Torga, Jorge Román; Morel, Eneas NicolásWe present experimental results in deformation measurement and thickness change in polymer films employing Fourier domain interferometry. The set-up is a Michelson configuration in which interference signal betweeen light reflected from a reference arm is superposed with two reflection from the first and second interface from the film sample. Distance measurements for determination of deformation and thickness values were obtained after an inverse Fourier transform of the spectrum signal. With this configuration, measurements with 1 micron axial resolution, and 2mm dynamic range were obtainedItem Ruido Magnético Barkhausen y Emisión Magneto Acústica en probetas de aleación Fe-1 wt % Cu(2009-11) Gomez, Martín; López Pumarega, Isabel; Torres, Darío; Nuñez, Nicolás; Armeite, María; Ruzzante, JoséTanto el Ruido Barkhausen (RB) como la Emisión Magneto Acústica (EMA), en materiales ferromagnéticos, dependen de las características microestructurales de los mismos y forman parte de las técnicas de caracterización no destructivas. El aumento de la vida útil de los reactores nucleares en servicio es de interés mundial, siendo la integridad de los recipientes de presión un aspecto fundamental a resolver. Estos recipientes de presión están construidos en aceros ferríticos de baja aleación con presencia crítica de impurezas tales como el Cu. Por otro lado, son bien conocidos los efectos perjudiciales de la presencia de Cu en aleaciones base Fe debido a que su segregación en borde de grano fragiliza su microestructura. En este trabajo se utilizaron probetas de Fe-1wt % Cu realizadas en Japón y que son parte de un “Segundo Ensayo Inter-Laboratorios”. Para simular la degradación y el proceso de envejecimiento producido en aceros de recipientes de presión de reactores nucleares, sin necesidad de irradiación, se realizaron sobre las probetas distintos tratamientos tanto térmicos como mecánicos. Cabe destacar que las muestras fueron tratadas en el país de origen. En este trabajo se presentan los primeros resultados de las mediciones de RB, EMA, rugosidad y conductividad. Se comparan el RMS (Root Mean Square) de las diversas señales y se las asocia con los cambios microestructurales que surgen de los distintos tratamientos termomecánicos.