1,039 research outputs found
Finite Element Analysis Of A Cup Deep Drawing Process [estudo Do Processo De Embutimento Profundo De Copo Pelo Metodo Dos Elementos Finitos]
No full textDeep drawing processes have an important role in manufacturing, mainly in the automotive industry. The increasing competition requires that design and manufacture of dies be fast and without errors. New forms to develop the dies have been used. The finite element method has helped engineers to reduce errors during die development. In this paper an elasto-plastic element was used to simulate the cylindrical deep drawing of an ABNT 1006 steel cup. The simulation made possible the determination of the forces, thickness and circumferential strains occurring during the deep drawing process, which were compared to experimental results.212355363(1993) ANSYS User's Manuals, 1. , (Procedures), 2 (Commands), 3 (Elements) and 4 (Theory), Swanson Analysis Systems IncBathe, K.J., (1982) Finite Elements Procedure in Engineering Analysis, , Prentice-Hall, Englewood CliffsBorst, R., Feenstra, P.M., Studies in anisotropic plasticity with reference to the hill criterion (1990) International Journal of Numerical Methods in Engineering, 29, pp. 315-336Bortolussi, R., (1996) Simulação do Processo de Estampagem Profunda de Corpos Cilíndricos Através do Método dos Elementos Finitos, pp. 81-88. , Dissertação de Mestrado, UNICAMP, cap. 5Bresciani, Fo., Button, S.T., Gomes, E., Nery, F.A.C., Zavaglia, C.A.C., (1996) Conformação Plástica dos Metais, p. 127. , E., Ed. UNICAMPChou, C.H., Pan, J., Analysis of sheet metal forming operations by a stress resultant constitutive law (1990) International Journal of Numerical Methods in Engineering, 29, pp. 315-336Cook, R.D., Malkus, D.S., Plesha, M.E., (1989) Concepts and Applications of Finite Element Analysis, , John Willey &Sons, 3a EdiçãoDarendeliler, H., Altan, T., Analysis of axisymmetric cup drawing in relation to friction (1996) Journal of Materials Processing Technology, 58, pp. 293-301Dieter, G.E., (1984) Workability Testing Techniques, , ASM InternationalGontier, C., About the numerical simulation of the sheet metal stamping process (1994) International Journal of Numerical Methods in Engineering, 37, pp. 669-692Guo, Y.Q., Batoz, J.L., Detraux, J.M., Duroux, P., Finite elements procedures for strain estimations of sheet metal forming parts (1990) International Journal of Numerical Methods in Engineering, 30, pp. 1385-1401Mahdavian, S.M., He, D., Product thickness analysis in pure cup drawing (1995) Journal of Materials Processing Technology, 51, pp. 387-406Keck, P., Wilhelm, M., Lange, K., Application of the finite element method to the simulation of sheet forming processes: Comparison of calculations and experiments (1990) International Journal of Numerical Methods in Engineering, 30, pp. 1415-1430Lee, D., Majlessi, S.A., Vogel, J.H., Process modeling and simulation for sheet metal (1989) Metals Handbook, 14, pp. 911-927. , 9th Edition ASM InternationalOñate, E., Zienkiewicz, O.C., A viscous shell formulation for the analysis of thin sheet metal forming (1983) International Journal of Mechanical Science, 25 (5), pp. 305-335Rowe, G.W., Strugess, C.E.N., Hartley, P., Pillinger, I., (1991) Finite Element Plasticity and Metal Forming Analysis, , Cambridge University Press, 1a EdiçãoSchey, J.A., (1983) Tribology in Metalworking, , ASM InternationalSlater, R.A.C., (1977) Engineering Plasticity, , The Macmillian Pres
Author Correction: New perspectives on Neanderthal dispersal and turnover from Stajnia Cave (Poland)
No full textThe Author contributions section now reads:“W.N., A.N. and S.T. designed research; A.P., M.H., W.N., S.B., M.U., A.M., H.F., M.D.B., P.S., K.S., M.Ż., A.W., A.N. and S.T. performed research; A.P., M.H., W.N., S.B., M.U., A.M., H.F., M.D.B., P.S., K.S., M.Ż., A.W., A.N. and S.T. analysed data; A.P., M.H., S.T., W.N. and S.B. wrote the paper with the collaboration of all the co-authors.
Author Correction:A 41,500 year-old decorated ivory pendant from Stajnia Cave (Poland)
No full textCorrection to: Scientific Reports https://doi.org/10.1038/s41598-021-01221-6, published online 25 November 2021The original version of this Article contained errors in the author list where Marjolein D. Bosch was omitted from the author list, and Mikołaj Urbanowski was incorrectly listed as an author of the original Article, and has subsequently been removed.The Author contributions section now reads:“S.T. W.N. and A.N. conceived the project; S.T., W.N., A.P., M.B., S.C., M.D., H.F., A.M., M.D. B., D.P., M.P.R., C.M.R., V.S-M., G.M.S., P.S., M.S., K.S., A.V., F.W., H.W., A.W., M.Z., S.B., A.N., J-J. H., performed research; S.T., A.P., W.N., M.B., M.D.B., S.C., M.D., H.F., A.M., D.P., M.P.R., C.M.R., V.S-M., G.M.S., P.S., M.S., K.S., A.V., F.W., H.W., A.W., M.Z., S.B., A.N., J-J. H. analysed all archaeological data; S.T. and A.P. wrote the paper with the collaboration of all the co-authors.”The original Article and its accompanying Supplementary Information file have been corrected
Lovecraft and Religion
No full textThe article was originally published as a chapter in S.T. Joshi’s book Lovecraft and a World in Transition: Collected Essays on H. P. Lovecraft (New York: Hippocampus Press 2014, pp. 187-195). The presented version was kindly provided to „Creatio Fantastica” by the Author without any copyright fee and translated into Polish by Magdalena Wąsowicz
Numerical And Experimental Analysis Of The Microstructural Evolution During Cross Wedge Rolling Of V-ti Microalloyed Steel [análise Numérica E Experimental Da Evolucão Microestrutural Durante A Laminação Transversal Com Cunha De Um Aço Microligado Ao V-ti]
No full textThe improvement of manufacturing processes to assure product quality and reduce the amount of raw material and energy is the main objective of many recent researches. Some of them study cross wedge rolling (CWR) as a substitute to hot upsetting in the manufacture of stepped shafts, pins, eccentric shafts and many other mechanical parts. In this process a cylinder is deformed by two wedge tools assembled on plane plates that move tangentially one against the other. The main objective of this work is to study the thermomechanical behaviour of medium carbon steel during hot CWR by means of a numerical analysis. The numerical results will be compared to the microstructure of microalloyed steel samples which were submitted to CWR experimental tests. The results suggested that dynamic recrystallization was present during CWR and that microstructures in the austenitic region were very refined.624495502Danno, A., Tanaka, T., Hot forming of stepped shafts by wedge rolling with three rolls (1984) Journal of Mechanical Working Technology, 9, pp. 21-35Dean, T.A., Fu, X.P., Past developments, current applications and trends in the cross wedge rolling process (1993) International Journal of Machine Tools and Manufacture, 33 (3), pp. 367-400Gentile, F.C., (2004) Estudo Do Processo De Laminação Cruzada Com Cunha (cross Wedge Rolling) Para Fabricação De Eixos Escalonados, , UNICAMP, agosto de, Tese de DoutoradoJonas, J.J., Dynamic recrystallization-scientific curiosity or industrial tool? (1994) Mat. Scie. and Eng., A184, pp. 155-165McQueen, H.J., Jonas, J.J., Recovery and recrystallization during high temperature deformation (1976) Treatise On Materials Science and Technology, 6, pp. 393-493. , In: ARSENAUT, R. J. (ed.), New York: Academic PressQiang, L.I., Lovell, M.R., Slaughter, W., Tagavi, K., (2002) Journal of Materials Processing Technology, pp. 125-126+248-257Regone, W., Jorge Jr., A.M., Balancin, O., (2000) Metodologia Para Determinar Os Tipos De Amaciamentos Que Atuam Em Processos Termomecânicos, , CBECIMAT, 14.São Pedro - SP, 3 a 6 de dezembro deda Silva, M.L.N., Regone, W., Button, S.T., Microstructure and mechanical properties of microalloyed steel forgings manufactured from cross-wedge-rolled preforms (2005) Scripta Materialia, 54, pp. 213-217Weronski, W., Pater, Z., Selection of geometric parametrs of transverse wedge rolling tools (1992) Journal of Materials Processing Technology, 34, pp. 273-28
Aluminium Extrusion Analysis By The Finite Volume Method
No full textPresent work proposes a novel numerical scheme to calculate stress and velocity fields of metal flow in axisymmetric extrusion process in steady state. Extrusion of aluminium is one main metal forming process largely applied in manufacturing bars and products with complex cross section shape. The upper-bound, slab, slip-line methods and more recently the numerical methods such as the Finite Element Method have been commonly applied in aluminium extrusion analysis. However, recently in the academy, the Finite Volume Method has been developed for metal flow analysis: literature suggests that extrusion of metals can be modelled by the flow formulation. Hence, metal flow can be mathematically modelled such us an incompressible non linear viscous fluid, owing to volume constancy and varying viscosity in metal forming. The governing equations were discretized by the Finite Volume Method, using the Explicit MacCormack Method in structured and collocated mesh. The MacCormack Method is commonly used to simulate compressible fluid flow by the finite volume method. However, metal plastic flow and incompressible fluid flow do not present state equations for the evolution of pressure, and therefore, a velocity-pressure coupling method is necessary to obtain a consistent velocity and pressure fields. The SIMPLE Method was applied to attain pressure-velocity coupling. This new numerical scheme was applied to forward hot extrusion process of an aluminium alloy. The metal extrusion velocity fields achieved fast convergence and a good agreement with experimental results. The MacCormack Method applied to metal extrusion produced consistent results without the need of artificial viscosity as employed by the compressible flow simulation approaches. Therefore, present numerical results also 2suggest that MacCormack method together with SIMPLE method can be applied in the solution of metal forming processes in addition to the traditional application for compressible fluid flow.172183Hill, R., (1950) The Mathematical Theory of Plasticity, , Oxford University PressAvitzur, B., (1980) Metal Forming, the Application of Limit Analysis, , Marcel Dekker, N.YJohnson, W., Sowerby, R., Venter, R.D., (1982) Plaine Strain Slip-Line Fields for Metal Deformation Processes, , Pergamon Press, OxfordMellor, P.B., Johnson, W., (1985) Engineering Plasticity, , Van Nostrand ReinholdKobayashi, S., Oh, S., Altan, T., (1989) Metal Forming and the Finite-Element Method, , Oxford University PressValberg, H.S., (2010) Applied Metal Forming: Inclunding FEM Analysis, , edited by Cambridge University Press, London, UKThomsen, E.G., Frisch, J., Stresses and strains in cold-extruding 2S-O aluminum (1955) Trans. ASME., 77, pp. 1343-1353Johnson, W., Kudo, H., (1962) The Mechanics of Metal Extrusion, , edited by Manchester University Press, Manchester, UKGhosh, S., A new finite element description for simulation of metal forming processes (1989) Numerical Methods in Industrial Forming Processes- Numiform, 89, pp. 159-164. , E.G. Thompson, R.D. Wood, O.C. Zienkiewicz and A. Samuelson (Eds), A.A. BalkemaZienkiewicz, O.C., Huang, G.C., Adaptive modelling of transient coupled metal forming processes (1989) Numerical Methods in Industrial Forming Processes- Numiform, 89, pp. 3-10. , E.G. Thompson, R.D. Wood, O.C. Zienkiewicz and A. Samuelson (Eds), A.A. BalkemaAltan, T., Kobayashi, S., A numerical method for estimating the temperature distribution in extrusion through conical die (1968) J. Eng. Ind., 90, pp. 107-118Sellars, C.M., The physical metallurgy of hot working (1980) Hot Working and Forming Processes, pp. 3-15. , C.M. Sellars and G.J. Davies ( Eds), Metals Society, LondonSellars, C.M., Computer modelling of hot-working processes (1985) Mat. Sci. Eng., 1, pp. 325-332Jain, P.C., (1976) Plastic Flow in Solids (Static, Quasistatic and Dynamic Situations including Temperature Effects), , University College of Swansea, Wales, Ph.D. thesisDawson, P.R., Thompson, E.G., Steady-state thermo mechanic finite element analysis of elastoviscoplastic metal forming processes (1977) Numerical Modelling of Manufacturing Processes, pp. 167-182. , ASME, PVP-PB-025Zienkiewicz, O.C., Godbole, P.N., Flow of plastic and viscoplastic solids with special reference to extrusion and forming processes (1974) Int. J. Num. Meth. Engng., 8, pp. 3-16Zienkiewicz, O.C., Jain, P.C., Onate, E., Flow of solids during forming and extrusion: Some aspects of numerical solutions (1978) Int. J. Solids Struct., 14, pp. 15-38Oñate, E., Cervera, M., Zienkiewicz, O.C., A finite-volume format for structural mechanics (1994) Int. J. Num. Meth. Engng., 37, pp. 181-201Demirdzic, I., Martinovic, D., Finite volume method for thermo-elasto-plastic stress analysis (1993) Computer Meth. Applied Mech. and Engng., 109, pp. 331-349Bailey, C., Cross, M., A finite volume procedure to solve elastic solid mechanics problems in three dimensions on an unstructured mesh (1995) Int. J. Num. Meth. Engng., 38, pp. 1757-1776Greenshields, C.J., Weller, H.G., Ivankovic, A., The finite volume method for coupled fluid flow and stress analysis (1999) Comput. Model Simul. Eng., 4, pp. 213-218Wenke, P., Whell, M.A., A finite volume method for solid mechanics incorporating rotational degrees of freedom (2003) Computers and Structures, 81, pp. 321-329Bressan, J.D., Martins, M.M., Vaz Jr., M., Stress evolution and thermal shock computation using the finite volume method (2010) Journal of Thermal Stresses, 33, pp. 533-558Programmer's Guide, , http://www.openfoam.com/docs/Jasak, H., (1996) Error Analysis and Estimation for the Finite Volume Method with Applications to Fluid Flows, , Ph.D. Thesis, Imperial College LondonBasic, H., Demirdzic, I., Muzaferija, S., Finite volume method for simulation of extrusion processes (2005) Int. J. Num. Meth. Engng., 62, pp. 475-494Martins, M.M., Bressan, J.D., Button, S.T., Ivankovic, A., Extrusion process by finite volume method using openfoam software (2010) International Conference on Advances in Material and Processing Technologies - AMPT2010, , F. Chinesta, Y. Chastel, M. El Mansori, (Eds), Paris, American Institute of PhysicsTannehill, J.C., Anderson, D.A., Pletcher, R.H., (1997) Computational Fluid Mechanics and Heat Transfer, , Taylor & Francis, LondonMartins, M.M., Bressan, J.D., Button, S.T., Metal extrusion analysis by finite volume method (2013) XII International Conference on Computational Plasticity Fundamentals and Applications COMPLAS 2013, , In: E. Oñate, D.R.J. Owen, D. Peric and B. Suárez (Eds), BarcelonaHensel, A., Spittel, T., (1978) Kraft- Und Arbeitsbedarf Bildsamer Formgebungsverfahren, , VEBDeutscher Verlag fur Grundstoffindustrie, LeipzigMartínez, H.V., Coupard, D., Girot, F., (2006) J. Mat. Proc. Techn., 173, pp. 252-25
Experimental research on the effects of surface screens on a mobile bed
No full textIn 2000 the Dutch government chose a new point of view for the Dutch rivers: “Room for the River”. This viewpoint is the basis for a new approach of high water protection in the Netherlands. Instead of strengthening and raising the dikes, solutions must be based on space and spatial quality. One of the suggested measures is the addition of secondary channels. The purpose of these channels is enlarging the conveyance area and the ecological role of the river. Maintaining the profile of these channels involves substantial financial consequences. Finding a sustainable solution for undesired erosion or sedimentation is the main focus of this study. The research question is stated as follows: “How can the undesired erosion or sedimentation in secondary channels be corrected with a temporary but sustainable solution in the form of surface screens?”. The main part of this study is an experimental study on the effects of surface screens on a mobile bed. The design of the physical experiments requires choices about the geometry of the flume. The experiments were carried out with a straight flume and with a dividing wall. Preparing the experiments requires information about the flume facility. The experiments have been carried out in the Environmental Fluid Mechanics Laboratory of DUT. The upstream boundary conditions are discharge and velocity distribution. The downstream boundary condition consisted of a fixed water level. The water level was kept constant along the natural slope of the surface. The experiments consist of taking velocity and bed level. The angle of attack and the penetration depth were chosen to be variable. The angle of attack was varied between 15 and 25 degrees. With these relatively small angles the screen acts as guidance for the flow, instead of an obstruction. The penetration depth was varied between 20% and 60% of the water column. The initial test run determined the optimal measurement duration and the initial equilibrium. Four representative cases have been described in detail, giving support to the general conclusions. The flow pattern changes under influence of the surface screen. The main flow direction is guided by the screen, introducing a transverse velocity at the surface. As flow continuity in the flume has to be maintained, the water near the bottom is forced to have a transverse velocity in opposite direction. Redistribution of the suspended transport and the bottom transport was induced. This generated locations were the actual transport did not meet the transport capacity, which gives rise to morphological changes. Next to the spiral motion the screen had an effect on the longitudinal flow velocities. The attacked side of the flume experiences a higher velocity, thereby having a higher transport capacity. This higher capacity gives rise to local erosion of the bed. At the unattacked side, sedimentation occurs, thereby rising the bed level. In the B-series of the experiment a dividing wall was added. The screen in front of the bifurcation gave rise to the same two processes, but the wall introduced an extra effect. The screen influenced the bifurcation relationship. The bed level adapted to the new conditions. The upstream effect of the bifurcation is explained by changes in water level topography, thereby influencing the backwater curve. In general the wall amplified the morphological development of the bed. Finally some suggestions have been made for the practical application of surface screens. In general the screens can be applied in a (secondary) channel or in front of a bifurcation. The use of a screen inside a channel has an advantage not to interfere with the navigation channel. The advantage of a screen in front of a bifurcation is influencing two channels simultaneously. One of the main disadvantages of the latter is the possibility of disturbing the delicate bifurcation relationship. When carefully implemented this effect can simultaneously be the main advantage of this screen layout, as the morphological response increases.Hydraulic EngineeringCivil Engineering and Geoscience
Pedagogical ideas of S.T. Shatsky
No full textU radu se prate osnovne pedagoške ideje poznatog ruskog i sovjetskog društvenog radnika i pedagoga S. T. Šackog. Članak polazi od osnovnih informacija njegove biografije, neprekidno povezane sa radom u prosveti i razmišljanjima o vaspitanju, prikazujući ih kao podlogu razvoja njegovih pedagoških ideja. Dalji tekst kratko iznosi njegove osnovne ideje u tematskim celinama o kritici škole, cilju vaspitanja, škole budućnosti, predškolskom i vanškolskom vaspitanju, didaktičkim shvatanjima, položaju deteta u vaspitnom procesu, radu učitelja i mestu škole u društvenoj sredini. Rad pokušava da dovede u vezu shvatanja Šackog sa savremenim pogledima na iste probleme. U tekstu se, takođe, može uočiti nekoliko tema za razmišljanje koje su naročito izdvojene u zaključnom delu članka: trajnost pitanja o vaspitanju, odnosno pedagoških problema, mogućnosti ostvarivanja ideja o promeni škole kao institucije vaspitnog sistema, odnos rada u prosveti i društvenog angažovanja.The author discusses the pedagogical ides of a well known Russian and Soviet social worker and pedagogue S.T. Shatsky. The report starts with the basic information from his biography, always in connection with his work in education and his contemplation on education, showing them as a background for the development of his pedagogical ideas. It proceeds by' an account on hid ideas in themes on criticism of school, the objective of education of the school of future, pre school and out of school education, didactic ideas, the position of child in the process of education, the work of the teacher and the place of school in the social milieu. The author attempts to bring together Shatsky's ideas and the modern attitudes to the same problems. The text also offers a number of topics for discussion, especially dealt with in the closing part: the duration of the issue of education, i.e. pedagogical problems, the possibility' of realization of the ideas on the change of school as a institution of education system, the relation of work in education and social engagement
Stabilizing Control System of a Platform of a Buoy for Offshore Wind Assessment
No full textThe purpose of this project is to design a control system to stabilize a platform on a buoy. Stabilization of the platform on the buoy is needed for reliable measurements of wind speed and wind direction on sea using LiDAR (Light Detection And Ranging) modules. These modules use the reflection of particles in the air to measure the wind speed and wind direction. This report is a description of the design of a prototype for a buoy with a stabilized platform. The research contains a study on the behavior of a buoy on waves, a description of the choices made for the design, a description of the used test methods, the test results and some recommendations for improvements on the design, based on the test results. The platform is controlled by three linear actuators of adjustable length. The angle of tilt of the platformis measured with a gyroscope and is used for controlling the linear actuators. The platform is able to compensate an angle of tilt that is smaller than 38° . The reaction time on deviations that are smaller than 10° is less than 1.2 seconds. The reliability on the long term must be improved, through implementation of some recommendations. One of these recommendations is the use of a Kalman filter to prevent long term drift of sensor output by combining different kinds of sensors.Electrical EngineeringElectrical Engineering, Mathematics and Computer Scienc
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