Numerical Modeling Of Heat Effects During Thermal Manufacturing Of Aero .
Proceedings of the World Congress on Engineering 2012 Vol IIIWCE 2012, July 4 - 6, 2012, London, U.K.Numerical Modeling of Heat Effects duringThermal Manufacturing ofAero Engine ComponentsLoucas Papadakis, Gregor Branner, Alexander Schober, Karl-Hermann Richter and Thomas Uihlein Abstract— In production of aero engine componentsinnovative advance manufacturing techniques, i.e. selectivelaser melting (SLM) and electron beam welding (EBW), arecurrently being developed. Structural properties andgeometrical accuracy of aero engine structures can bedetermined in advance of manufacturing steps by means ofsimulation methods in order to ensure their final quality. Forsupporting this effort, reduced models were chosen forperforming tests and simulation analyses on the developmentof the form accuracy and residual stresses in the structure. Inthis contribution an approach is introduced which includes thenumerical abstraction of the real problem, so that feasibilityand clarity of the developed models are attained. The renderedresults will provide for an improved process design for thefuture manufacture of low shape distortion aero enginecomponents.Index Terms— electron beam welding, finite elementanalysis (FEA), laser additive manufacturing, processstructure interaction,I. BACKGROUND AND MOTIVATIONIN recent years models of various manufacturing processeshave become increasingly important in modern industries,which are based to a large extent on computer aidedtechniques. Such models supported by numerical methods,accompany not only the development phase of the productlife cycle but also the manufacturing itself [1], [2]. Duringmanufacturing it is essential to achieve product accuracyand to follow and specify structural properties by means ofcomputational methods [3]–[5]. Furthermore, manufacturingprocesses and production systems can be pre-designed andoptimized prior to prototype production for the needs of theproduction lines with the support of simulations. This canManuscript received March 3, 2012; revised April 4, 2012. This workwas partly supported by the MTU Aero Engines GmbH, D-80995 Munich,Germany.L. Papadakis is with the Department of Mechanical Engineering,Frederick University, Nicosia, Cyprus (phone: 35722345159 ext. 115; fax: 3572243823; e-mail: l.papadakis@frederick.ac.cy).G. Branner was with the Institute for Machine Tools and IndustrialManagement (iwb), Technische Universitaet Muenchen, Germany. He iscurrently with the AUDI AG, D-85045 Ingolstadt, Germany (e-mail:gregor.branner@audi.de).A. Schober is with the Institute for Machine Tools and IndustrialManagement (iwb), Technische Universitaet Muenchen, Germany (e-mail:alexander.schober@iwb.tum.de).K.-H. Richter is with the MTU Aero Engines GmbH, D-80995 Munich,Germany (e-mail: karl-hermann.richter@mtu.de)T. Uihlein is with the MTU Aero Engines GmbH, D-80995 Munich,Germany (e-mail: thomas.uihlein@mtu.de)ISBN: 978-988-19252-2-0ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)improve the quality of the final product, shorten processduration and minimize costs by avoiding trial-and-errorduring the process and plant design, attain usefulinformation about the behaviour of material duringmanufacturing, and supply valuable findings on theinteraction of process and structure.Numerical methods may contribute to the improvement ofthe quality of structures in relation to their geometrical andstructural properties. Especially in the aircraft industries,where product quality, process approval and safety aresignificant issues, computer aided techniques are expedient.Advance simulation methods may help to improve structuralproperties and provide for the shape accuracy during thestage of manufacturing [6]. Besides the constructivecharacteristics and material definition during the productdevelopment phase, manufacturing processes influence thematerial strength and the stability of the structure,particularly due to heat treatment. Such effects can, on theone hand, improve structural properties (due to the increaseof the yield stress in case of friction stir welding and laserforming) and, on the other hand worsen them (due to theundesirable development of cracks) [7]–[9].Available research works provide a wide spectrum ofmodeling methods and their applications for differentmanufacturing methods. The various influencingphenomena are considered in different modeling stepswithin the simulation. The significance of the modeling andprocess parameters are discussed for the processes of laseradditive layer manufacturing and electron beam welding onpractical reduced demonstrating examples.Different aspects of the process-structure interactionwithin the simulation methodologies are introduced in thiscontribution, i.e. heat source definition, process sequences,clamping conditions etc. Based on these findings, the maingoal of this paper is to suggest and validate simulationsmethods for supporting manufacturing processes for futureapplications in aircraft industries.II. THERMAL MANUFACTURING PROCESSES FOR AEROENGINE COMPONENTSMetal based Selective Laser Melting (SLM) and ElectronBeam Welding (EBW) are gaining an increasing marketshare in the field of production technology [10], [11]. Twomain technological advantages are responsible for theincreasing success of these innovative technologies. First,the growth can be referred to the process flexibility and thepossibility to produce parts with high geometric complexity.WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol IIIWCE 2012, July 4 - 6, 2012, London, U.K.Second, the capability to manufacture components of highshape accuracy and structural quality is a further decisiveadvantage. Today, the so called layerwise fabrication ofparts is feasible with a lot of different materials, e.g.aluminium alloys, hot forming steel, tungsten carbide ortitanium [12]–[15]. Hence, numerous industries withmiscellaneous requirements are interested in SLM.Especially parts with a high complexity and internalstructures, e.g. cooling channels, are economically realisableby SLM. Representative applications for the aircraftindustry [16], which are manufactured with an Inconel alloy, are illustrated in Fig. 1.Fig. 1. Aero engine structural components (combustion chamber, turbineblade) produced by SLM [16]Even if extensive technical progresses have been made inrecent years compared to conventional manufacturingtechnologies, SLM and EBW still comprehend severalprocess deficiencies [17]. Especially the temperaturegradient mechanism (TGM) as a result of the locallyconcentrated energy input leads to residual stresses, crackformation and part deformations, as shown in Fig. 2 [18],[19]. Primarily these residual stresses contribute to a crackformation or a disconnection of parts from the buildingplatform in case of SLM [20]. Furthermore the shapeaccuracy as well as the mechanical strength of parts isinfluenced thereby [21]. To cope with these challenges,numerical solutions by means of the FEA compriseadequate algorithms [22], [23].Fig. 2. Laser based consolidation of metal powder, residual stresses andcrack formation in SLMThe presented work contains different approaches toinvestigate residual stresses and shape deformation withinthe SLM and EBW process. First, a numerical method,considering a coupled thermal and mechanical simulationbased on a three-dimensional model including temperaturedependant material properties for powder and solid isdescribed [24]. Within this simulation, specific requirements(e.g. the activation of fused powder layers, weld gabdefinition) and boundary conditions (e.g. convection andradiation) of the thermal manufacturing technologies areconsidered [19]. In order to evaluate the achievable processstability and the structural part properties, the investigationsin case of SLM are containing additionally variable buildingISBN: 978-988-19252-2-0ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)platform temperatures TBP and support lattice parameters(e.g. the support lattice distance dSG,). Representativestudies indicate, that these parameters imply the largestinfluence on the resulting residual stresses adjacent to thescanning strategy [19]. In the other hand during EBW theclamping conditions play a decisive role along with theexact modelling of the weld pool geometry.III. SIMULATION APPROACHES FOR THERMALMANUFACTURING PROCESSESSo far, in the field of thermal manufacturing processesvarious heterogeneous simulation approaches exist forsolving single physical phenomena. The approaches arestructured on the basis of the sub areas process, structureand material. Due to analogies among the simulation ofbeam based welding technologies, relevant basic methods[25] are being adopted and specifically extended to theapplication in the thermal manufacturing processesincluding SLM. Fig. 3 shows an appropriate subdivision ofthe numerical simulation of layer based processes.Moreover, coupling respectively interfaces between thespecific objectives of simulation are possible.A. Process SimulationAccording to the process simulation of weldingtechnologies, the underlying numerical algorithms can beadapted in order to investigate the absorptivity or themechanisms of powder solidification also in SLM. Withinthese considerations, the density change duringsolidification of the powder is as important as the melt poolstability. In comparison to welding technologies, SLMtechnologies inherit additional complexity. Since theprocess stability and the solidification of the powdermaterial depend on the layer thickness and the processparameters, accordant influences are necessary for thesimulation. In addition, the process and material specificmechanisms of solidification are relevant. An exemplaryapplication field for the process simulation in SLM is theanalysis of the so called balling-effect [26].B. Material SimulationThe obtained results of the process simulation can beused in order to investigate the microstructure, which isinfluenced through several heat effects, by means of thematerial simulation. Beyond the hardness of structures,especially the metallurgical phase transformations andconsiderations concerning crack susceptibility are relevant.Thus, node temperatures and the melt pool composition areexchanged between the process and the material simulation.Contrary, the specific enthalpies and the thermo-physicalmaterial properties are useful for the process simulation.During multi-layer welding technologies as well as additivemanufacturing technologies the structure is underlyingalternating heating and cooling cycles. Hence, the materialsimulation is challenged by adequate algorithms for theprediction of the microstructure kinetics.C. Material SimulationAnalogue to the process and material simulation, thestructure simulation of thermal manufacturing processesconstitutes a combination of available techniques. First, theWCE 2012
Proceedings of the World Congress on Engineering 2012 Vol IIIWCE 2012, July 4 - 6, 2012, London, U.K.layer dynamics and the attendant density changes during thesolidification are relevant in modeling. Second,metallurgical phase transformations affect the structuredeformations as well as the residual stresses. Furthermore,there is a need for applicable measurement techniques, sincethe occurring temperature gradients are at about 100 K/s [6],[19]. Thus, the structure simulation is challenged by thedevelopment of adequate methods for the calculation ofresidual stresses and deformations due to the plasticizationin the heat affected zone. Beyond the transient temperaturefield, particularly predictions concerning the layerdelamination or the strength of supports are essential. Inaddition, the influence of the transformation plasticity ondeformations and residual stresses has to be considered. Asa representative example for the use of simulationapproaches in SLM, the structure based method is describedin detail.processsimulationmolten pool geometrylocal temperature fieldprocess efficiencyprocess stabilitystructuralsimulationtemperature fieldresidual stressesdeformationstiffnessstrengthsimulationof rostructure stressesmicrostructure statephase transformationhardnesscrack formationmechanical materialproperties,transformation strainFig. 3. Classification of simulation approaches in thermal manufacturingprocesses according to Radaj [25]IV. MODELING OF TRANSIENT PHYSICAL EFFECTS INSTRUCTURAL SIMULATIONA. SLM ProcessTo account for the numerous physical effects withinSLM, different strategies for an industrially useful structuresimulation are mandatory. Due to the available computingpower, it is not always feasible to model every singlescanning vector within the energy application. Hence, thefollowing chapters describe a specific model designed forthe investigation of whole parts [20]. Contrary to a morespecified layer based model [22], which considers the exactscanning strategy, it is the aim of the applied model tosubstitute the scanning vectors of every layer by so calledscanning areas. Thus it is in principal possible to calculatethe residual stresses and deformations of entire parts.To evaluate the process stability in dependence of severalparameters with a thermo-mechanical simulation, themanufacturing process of a twin-cantilever is considered.The tool steel cantilever (alloy 1.2709, X3NiCoMoTi18-95) has overall dimensions of 70 x 15 x 12 mm³ and ispositioned on the building platform (see Fig. 4). Beneath theso called cantilever wings, support structures with thedimensions of 30 x 15 x 8 mm³ are located. In order toquantify the residual stresses of the cantilever, eightmeasuring points for the simulation and the experimentalvalidation with the neutron diffractometry along ahorizontal path are defined.For the geometry generation in the FEA, a specificinterface between the SLM manufacturing system and thenumerical simulation in ANSYS Multiphysics is used.Thereby, the scanning pattern serves as a base for theselection of corresponding nodes and elements.Accordingly, the underlying method allows therepresentation of the exact part orientation and the singlelayers due to the direct access to the manufacturing system’scontrol unit. Hence, supports are recognized as well throughthe algorithm.Within the simulation, the considered twin-cantilever issectioned in finite elements with dimensions of 1.0 x 1.0 x0.5 mm³ (cp. Fig. 4). The boundary conditions aredistinguished for the thermal and the mechanicalcalculation. In the thermal simulation, especially theconvection coefficients to the environment largely affect thecooling cycles of single fused layers and thus the residualstresses. In order to achieve a high accuracy according tothe real process conditions, specific convection coefficientsfor the surrounding powder αC,TC (twin-cantilever) and αC,S(support), the solidified surface αC,TC,O and the buildingplatform αC,BP are defined. The mechanical simulation istwin-cantilever: 70 x 15 x 12 mm³supports: 30 x 15 x 8 mm³building platform (section): 70 x 15 x 10 mm³twin-cantileversupportbuilding C,TC,Oplatformtwin-cantilever: 70 x 15 x 12 mm³supports: 30 x 15 x 8 mm³horizontal path (8 measuring pointsfor the neutron diffractometry)xxxxxxxxzxy C,TCsupports (1.2709)building platform(1.0037)position of the path:x [-35 mm; 35 mm]y 7,5 mmz 11 mmuzuxuzuyxy C,S C,BPcantilever wingszuz C,BP 1,0 x 106 W/(m²·K) C,TC,O 50 W/(m²·K) C,TC K,S 0 W/(m²·K)Fig. 4. Twin-cantilever for the process stability analysis and FE-geometry with thermal and mechanical boundary conditionsISBN: 978-988-19252-2-0ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol IIIWCE 2012, July 4 - 6, 2012, London, U.K.based on realistic clamping conditions, which comprehend afixation of the building platform in defined orientations ux,uy and uz. According to the boundary conditions, numerousdifferent material properties for the varying processconditions, distinguished between building platform,support and twin-cantilever, are necessary. In order tosimplify the simulation and to gain efficiency, the support isdefined as a continuum with specific adjusted materialproperties. Therefore, the density, the thermal conductivity,the elastic (Young’s) and shear modulus as well as thethermal expansion coefficient have to be modified accordingto a special developed and qualified method [20].V. SIMULATION RESULTS AND EXPERIMENTAL VALIDATIONIn addition to the scanning strategy, which was identifiedas a major influence on the structure in earlier investigations[8], especially the building platform temperature TBP and thesupport lattice parameter dSG affect the development ofresidual stresses and deformations in SLM. Hence, theserepresentative effects are varied within the simulation modelbased on the numerical formulation of occurring transientphysical effects, e.g. the TGM. After solving the simulationproblem of the layerwise manufacturing, another simulationstep allows to visualize the cantilever geometry after cuttingthe no longer required support, e g. by means of wireelectro discharge machining (EDM). Therefore, thecorresponding elements near the building platform have tobe deactivated in the FE-Model and a subsequent solvingprocess is done. This approach enables a relaxation of theresidual stresses and a further development of deformationsas it is also observed in reality. In the following chapter, theresults of the numerical simulation concerning longitudinalresidual stresses are compared to experimentalinvestigations using the neutron diffractometry.B. EBW ProcessAnalogue to the afore mentioned modelling method forSLM the modelling of EBW of a simplified geometry wasperformed by means of the FE-Software SYSWELD. Theexperimental setup and FE-model are shown in Fig. 5.Particular attention was given to the definition of thetemperature depending material properties of Inconel 718,the clamping conditions, the welding sequences and theirdirection, the weld pool formation during EBW and theweld gap existing in experiment prior to joining.Effect of the building platform temperature TBPConcerning the building platform temperature, Fig. 6illustrates a comparison of the longitudinal residual stressesfor TBP 20 C and TBP 200 C in sectionalrepresentation. Coincidentally, the simulated deformationsare displayed with a tenfold scaling. In the figure, the arealeft to the centre line characterizes stresses for a building jobat 20 C, whereas results for TBP 200 C are shown on theright side. Compared to an SLM process at ambienttemperature, an explicit preheating leads to larger extendedlongitudinal compressive stress divisions at the lower sideof the cantilever wings (σx,max -536 N/mm²), which areconnected to the supports. Beyond, the preheated structurefixturesclamped nodesypositioning pinwelding lineszxFig. 5. Experimental setup o for the shape distortion analysis and FEgeometry with mechanical boundary conditions xcompressive stressescompressive stresses x[N/mm²]TBP 20 CTBP 200 Cztensile 6355503652[N/mm²]TdSG 20 C mm 0.2TdSG 300 3.0 Cmmztensile stressesremarkabledeformationN/mm²N/mm²mmx-axis of the twin-cantileversimulation 20 Cdiffractometry 20 Csimulation 200 Cdiffractometry 200 Clongitudinal stresses xsectional representation, tenfold scalinglongitudinal stresses xsectional representation, tenfold scaling variation of the platform temperature TBP validation method: neutron diffractometry-527-402-277-152-2798223348473yx variation of the support lattice distance dSG validation method: neutron diffractometrymmx-axis of the twin cantileversimulation 0.2 mmsimulation 3.0 mmdiffractometry 0.2 mmdiffractometry 3.0 mmFig. 6. Simulated residual stresses in sectional representation in dependence of the building platform temperature and the support latticedistance; comparison of simulated and measured residual stresses along a defined pathISBN: 978-988-19252-2-0ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol IIIWCE 2012, July 4 - 6, 2012, London, U.K.shows larger deformations of the cantilever wings in thenegative z-coordinate direction. This effect especiallybecomes apparent through a decreasing gap betweensubstrate and supports.Effect of the support lattice distance dSGConcerning a variation of the support lattice distance dSG,comparable results like for different platform temperaturescan be derived. In Fig. 6, the centre line detaches twocantilever models with dSG 0.2 mm and dSG 3.0 mm.According to the illustration, a close-meshed support(dSG 0.2 mm) leads to higher temperature gradientsbetween the process zone and the substrate and thus tolarger compressive stresses at the upper and lower side ofthe cantilever wings (σx,max -527 N/mm²). Contrarily, thewide-meshed support (dSG 3.0 mm) causes max 473 N/mm²). Furthermore, a wide-meshed supportinvolves larger deformations of the cantilever wings in thenegative z-coordinate direction. Because of powderinclusions and a reduced heat conductivity, wide-meshedsupports show a comparable influence on the structural partbehaviour like an increased building platform temperature(e.g. TBP 200 C).Fig. 6 indicates for both, the simulation and the neutrondiffractometry, that the longitudinal stresses along thehorizontal path are continuously tensile 100 N/mm²;250 N/mm² in case of a close-meshed support(dSG 0.2 mm). Contrarily, the strains are disarranged intocompressive stresses for a considerable increase of thesupport lattice distance to dSG 3.0 mm (-260 N/mm²; 50 N/mm²). Furthermore, a good accordance of thesimulation and the neutron diffractometry is achieved in thecentre of the cantilever. While the longitudinal compressivestresses for the wide-meshed support significantly relax inthis area, the closed-meshed support causes a localminimum within the tensile stress range.The definition of heat source model for replicating theweld pool formation and the 3-d heat distribution instructure is an essential part of the simulation procedure ofthermal manufacturing processes. Fig. 7 shows the weldpool formation during thermal calculation of EBWcompared with weld seam macrographs and the comparisonof calculated with measured temperature cycles at specificpositions on the surface of the structure.Based on the theory regarding the development ofwelding distortions of the literature [21] is expected toobserve a shrinkage of the structure after the electron beamwelding process. This was observed in the above reducedmodel in the x-direction or tangential direction. Localplasticisation effects in the weld seam area, as shown in thecross section micrographs in Fig. 7, induce in combinationwith the overall structure stiffness (in respect to the neutralline) to a bending distortion in the y-direction (radial) and,consequently, to a shape change of the entire demonstratingstructure in the tangential direction. The simulation resultsMeasurement of temperature cycle at point 2.5 mmfrom weld line centre700temperature [ C]calibrated heat source modelTFehler 663,3 C600T 556,7 CTmax max556,76 C5004003002001005101520time [s]Simulation of temperature cycles at different pointsfrom weld line centre1000Tmax 980 C2,0 mmtemperature [ C]9008007006004,0 mmTmax 660 C500400300200100510152025time [s]Fig. 7. Weld pool formation in thermal calculation of EBW compared to weld seam macrograph and comparison of calculated withmeasured temperature cyclesISBN: 978-988-19252-2-0ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)WCE 2012
Proceedings of the World Congress on Engineering 2012 Vol IIIWCE 2012, July 4 - 6, 2012, London, U.K.of the EBW model meet qualitatively the expectations andexperiences from the theoretical principles, as seen in Fig. 8.distortion in y-direction (radial) [mm][3]distortion in x-direction (tangential) [mm]- 0.30- 0.25- 0.19- 0.14- 0.09- 0.030.0150.0690.1220.175[2]- 0.58- 0.43- 0.28- 0040050060070080090010001100[7][8][9]von Mises stresses (clamped) [MPa]von Mises stresses (unclamped) [MPa]Fig. 8. Structural results of welding distortion and residual stresses afterthe thermo-mechanical calculation of EBW[10][11]VI. CONCLUSIONS AND OUTLOOKOn the one side, the presented investigations in SLMconstitute, that both the building platform temperature TBPand the support lattice distance dSG affect the structural partbehaviour significantly. On the other side, the investigationsdemonstrate the applicability of the developed numericalmodels by means of the FEA for the prediction of residualstresses and deformations in dependence of various processparameters. Thus, higher process stability in SLM will beachieved based on preliminary simulations. In general, thenumerically calculated results for the cantilever geometryshow an adequate correlation with the experimental series.Nevertheless, it has to be mentioned, that the simulation wascarried out with several simplifications, e.g. the powderlayer thickness was set to 0.5 mm compared to 50 µmwithin the real process in order to achieve a more efficientsimulationRegarding the modelling and simulation of EBW aparameter study is necessary in order to identify the weightof the influence of each simulation parameter. Furthermore,a validation of the welding distortion results is conductedand will be presented in future work. In the future, theinvestigations of thermal manufacturing processes will befocussed on the variation of further process parameters (e.g.the orientation of parts in SLM) and further modellingstrategies and the improvement of the model accuracy. Inaddition, it is intended to develop specific modellingstrategies for the analysis of detailed scanning patternsbased on the system control of the manufacturing unit.Furthermore, industrially relevant parts, e.g. aircraftcomponents, will be analysed based on the thermomechanical simulation of SLM and 3][24][25][26]REFERENCES[1]K. Masubuchi, Analysis of Welded Structures Residual Stresses,Distortion and their Consequences. Massachusetts Institute ofTechnology: Pergamon Press, 1980.ISBN: 978-988-19252-2-0ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online)P. Åström, “Simulation of Manufacturing Processes in ProductDevelopment,” Ph.D dissertation, Luleå University of Technology,2004.S. Lutzmann, “Beitrag zur Prozessbeherrschung des Elektronenstrahlschmelzens,” Ph.D dissertation, Technische UniversitaetMuenchen, 2011.J. Goldak, M. Akhlaghi, Computational Welding Mechanics. NewYork: Springer, 2005.M. F. Zaeh, G. Branner, G. Strasser, “Process Chain for EfficientNumerical Simulation of Indirect Metal Laser Sintering (IMLS),” inProc. 18th Solid Freeform Fabrication Symposium, Austin, TX, 2007.L. Papadakis, “Simulation of the Structural Effects of Welded FrameAssemblies in Manufacturing Process Chains,” Ph.D dissertation,Technische Universitaet Muenchen, 2008.S. W. Kallee, E. D. Nicholas, W. M. Thomas, “Industrialisation ofFriction Stir Welding for Aerospace Structures,” 56th Int. Conf. onMetallic Welded Structures, Bucharest, Rumania, 6–11, Jul. 2003.K. G. Watkins, S. P. Edwardson, J. Magee, G. Dearden, P. French,R. L. Cooke, J. Sidhu, N. J. Calder, “Laser Forming of AerospaceAlloys,” in Proc. Aerospace Manufacturing Conf., Seattle, WA, Apr.16–19, 2001.V. Ploshikhin, A. Prikhodovsky, A. Ilin, C. Heimerdinge, F. Palm,“Mechanical-Metallurgical Approach for Prediction of SolidificationCracking in Welds,” in Mathematical Modelling of Weld Phenomena8, Technische Universität Graz, 2007, pp. 87–104.T. Wohlers, State of the Industry, Annual Worldwide Progress Report,Fort Collins, Colorado: Wohlers Associates 2009.D. v. Dobeneck, T. Lower, “Elektronenstrahlschweisen - DerzeitigerStand und Entwicklungstendenzen. ” in Grosse SchweistechnischeTagung (GST 2004), Magdeburg, 22–24, Sept. 2004, Dusseldorf:DVS 2004. ISBN: 3-87155-689-0.O. Nyrhilä, J, Kotila, M. Latikka, J. Hänninen, T. Syvänen, “DMLSand Manufacturing.” Solid Freeform Fabrication SymposiumProceedings 18, 2007, pp. 292–298.T. Sercombe, N. Jones, R. Day, A. Kop, “Heat treatment of Ti-6Al7Nb components produced by selective laser melting.” RapidPrototyping Journal, vol. 14, no. 5, pp. 300–304, 2008.K. Mumtaz, N. Hopkinson, “Top surface and side roughness ofInconel 625 parts processed using selective laser melting.” RapidPrototyping Journal, vol. 15, no. 2, pp. 96–103, 2009.G. V. Levy, R. Schindel, J. P. Kruth, “Rapid manufacturing and rapidtooling with layer manufacturing (LM) technologies, state of the artand future perspectives,” CIRP Annals - Manufacturing Technology,vol. 52, no. 2, pp. 589–609, 2003.F. Bechmann, J. Henzler, “Production and Quality Control ofAeronautical Parts manufactured by LaserCUSING ,” EUCOMASConference, Augsburg, 1, Jul. 2009.G. Branner, M. F. Zaeh, C. Groth, “Coupled-Field Simulation inAdditive Layer Manufacturing,” in Proc. 3rd Int. Conf. Polymers andMoulds Innovations, Ghent, Belgium, 17–19, Sept. 2008, pp. 184–193.M. Shiomi, K. Osakada, K. Nakamura, T. Yamashita, F. Abe,“Residual stress within metallic model made by Selective LaserMelting process”, CIRP Annals - Manufacturing Technology, vol. 53,no. 1, pp. 195–198, 2005.P. Mercelis, J. P. Kruth, “Residual stresses in selective laser sinteringand selective laser melting,” Rapid Prototyping Journal , vol. 12, no.5, pp. 254–265, 2006.M. F. Zaeh, G. Branner, “Investigations on residual stresses anddeformations in selective laser melting,” Production Engineering,vol. 4, no.1, pp. 35–45, 2010.J. P. Kruth, P. Mercelis, J. van Vaerenbergh, L. Froyen, M. Rombouts,“Binding mechanisms in selective laser sintering and selective lasermelting,” Rapid Prototyping Journal, vol. 11, no. 1, pp. 26–36, 2005.M. A. Chrisfield, Nonlinear Finite Element Analysis
application field for the process simulation in SLM is the analysis of the so called balling-effect [26]. B. Material Simulation The obtained results of the process simulation can be used in order to investigate the microstructure, which is influenced through several heat effects, by means of the material simulation.
2.12 Two-shells pass and two-tubes pass heat exchanger 14 2.13 Spiral tube heat exchanger 15 2.14 Compact heat exchanger (unmixed) 16 2.15 Compact heat exchanger (mixed) 16 2.16 Flat plate heat exchanger 17 2.17 Hairpin heat exchanger 18 2.18 Heat transfer of double pipe heat exchanger 19 3.1 Project Flow 25 3.2 Double pipe heat exchanger .
Numerical Modeling of Ablation Heat Transfer Mark E. Ewing,* Travis S. Laker,† and David T. Walker‡ ATK Aerospace Group, Brigham City, UT, 84302 A unique numerical method has been developed for solving one-dimensional ablation heat transfer problems. This paper provides a comprehensive description of the method,
2.1.1 Ground Loop Heat Exchanger Model. 11 2.1.1.1 Modeling of Vertical Ground Loop Heat Exchangers - Analytical. 21 2.1.1.2 Modeling of Vertical Ground Loop Heat Exchangers - Numerical. 33 2.1.1.3 Modeling of Vertical Ground Loop Heat Exchangers - Response Factors
14 D Unit 5.1 Geometric Relationships - Forms and Shapes 15 C Unit 6.4 Modeling - Mathematical 16 B Unit 6.5 Modeling - Computer 17 A Unit 6.1 Modeling - Conceptual 18 D Unit 6.5 Modeling - Computer 19 C Unit 6.5 Modeling - Computer 20 B Unit 6.1 Modeling - Conceptual 21 D Unit 6.3 Modeling - Physical 22 A Unit 6.5 Modeling - Computer
heat, a heat pump can supply heat to a house even on cold winter days. In fact, air at -18 C contains about 85 percent of the heat it contained at 21 C. An air-source heat pump absorbs heat from the outdoor air in winter and rejects heat into outdoor air in summer. It is the most common type of heat pump found in Canadian homes at this time.
HEAT CHANGE OVER VALVE B C R L2 L1 (HOT) Typical 3H/2C or 2H/1C Heat Pump System System: Indicates current mode of operation. AUXILIARY HEAT RELAY EMERGENCY HEAT RELAY Terminal 2 Heat 2 Cool Conventional System 2 Heat 2 Cool Heat Pump System 3 Heat 2 Cool Heat Pump System RC RH C B O G W/E W2 Transformer power (cooling) Transformer power .
heat exchangers is critical to the design and energy analysis of ground source heat pump systems. For detailed analysis and accurate simulation of the transient heat transfer in vertical ground loop heat exchangers, a numerical model is developed. The model is based on the two-dimensional, fully implicit finite volume formulation and utilizes an
Abstract—Recently, heat and mass transfer simulation is more and more important in various engineering fields. In order to analyze how heat and mass transfer in a thermal environment, heat and mass transfer simulation is needed. However, it is too much time-consuming to obtain numerical solutions to heat and mass transfer equations.
