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Sample records for thermomechanical processing steps

  1. Dual-phase ULCB steels thermomechanically processed

    International Nuclear Information System (INIS)

    Lis, A.K.; Lis, J.

    2001-01-01

    The design philosophy of the processing of dual-phase (D-P) ultra low carbon steels (ULCB) by thermomechanical treatment has been briefly discussed. Modelling of the structure evolution during thermomechanical rolling of ULCB steel was based upon the established empirical equations for yield flow at different conditions of: deformation temperatures, strain rates and stresses for applied amount of deformation during hot deformation compression tests. The critical amount of deformation needed for the occurrence of dynamic or static recrystallization was determined. The dependence of grain refinement of the acicular bainitic and polygonal ferrite of the accelerated cooling and amount of stored energy of deformation in steel has been evaluated. Effect of the decreasing of the finishing temperature of thermomechanical processing on the increase of the impact toughness of dual-phase microstructure consisted of the bainitie-martensite islands in the ferrite matrix has been shown. The effect of ageing process after thermomechanical rolling of heavy plates on fracture toughness values of J 0.2 for ULCB-Ni steels has been established from cod tests measurements. New low cost technology of rolling of ULCB steels dual-phase is proposed. (author)

  2. Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing

    OpenAIRE

    Górka J.

    2017-01-01

    This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by...

  3. Prediction of thermo-mechanical reliability of wafer backend processes

    NARCIS (Netherlands)

    Gonda, V.; Toonder, den J.M.J.; Beijer, J.G.J.; Zhang, G.Q.; van Driel, W.D.; Hoofman, R.J.O.M.; Ernst, L.J.

    2004-01-01

    More than 65% of IC failures are related to thermal and mechanical problems. For wafer backend processes, thermo-mechanical failure is one of the major bottlenecks. The ongoing technological trends like miniaturization, introduction of new materials, and function/product integration will increase

  4. Prediction of thermo-mechanical integrity of wafer backend processes

    NARCIS (Netherlands)

    Gonda, V.; Toonder, den J.M.J.; Beijer, J.G.J.; Zhang, G.Q.; Hoofman, R.J.O.M.; Ernst, L.J.; Ernst, L.J.

    2003-01-01

    More than 65% of IC failures are related to thermal and mechanical problems. For wafer backend processes, thermo-mechanical failure is one of the major bottlenecks. The ongoing technological trends like miniaturization, introduction of new materials, and function/product integration will increase

  5. Effect of cerium and thermomechanical processing on microstructure

    Indian Academy of Sciences (India)

    The effect of cerium content and thermomechanical processing on structure and properties of Fe–10.5 wt.%Al–0.8 wt%C alloy has been investigated. Alloys were prepared by a combination of air induction melting with flux cover (AIMFC) and electroslag remelting (ESR). The ESR ingots were hot-forged and hotrolled at ...

  6. Microstructure history effect during sequential thermomechanical processing

    International Nuclear Information System (INIS)

    Yassar, Reza S.; Murphy, John; Burton, Christina; Horstemeyer, Mark F.; El kadiri, Haitham; Shokuhfar, Tolou

    2008-01-01

    The key to modeling the material processing behavior is the linking of the microstructure evolution to its processing history. This paper quantifies various microstructural features of an aluminum automotive alloy that undergoes sequential thermomechanical processing which is comprised hot rolling of a 150-mm billet to a 75-mm billet, rolling to 3 mm, annealing, and then cold rolling to a 0.8-mm thickness sheet. The microstructural content was characterized by means of electron backscatter diffraction, scanning electron microscopy, and transmission electron microscopy. The results clearly demonstrate the evolution of precipitate morphologies, dislocation structures, and grain orientation distributions. These data can be used to improve material models that claim to capture the history effects of the processing materials

  7. Thermomechanical analysis of an electrically assisted wire drawing process

    OpenAIRE

    Sánchez Egea, Antonio José; González Rojas, Hernan Alberto; Celentano, Diego Javier; Jorba Peiró, Jordi; Cao, Jia

    2017-01-01

    Electrically-assisted wire drawing process is a hybrid manufacturing process characterized by enhancement of the formability, ductility and elongation of the wire drawn specimen. A thermomechanical model to describe the change of the mechanical response due to the thermal contribution is proposed in this work. Additionally, a numerical simulation was conducted to study the potential and limitations of this hybrid process by using two different hardening laws: a phenomenological and a dislocat...

  8. Thermomechanical Modelling of Friction Stir Welding

    DEFF Research Database (Denmark)

    Hattel, Jesper Henri; Schmidt, Henrik Nikolaj Blicher; Tutum, Cem Celal

    2009-01-01

    Friction Stir Welding (FSW) is a fully coupled thermomechanical process and should in general be modelled as such. Basically, there are two major application areas of thermomechanical models in the investigation of the FSW process: i) Analysis of the thermomechanical conditions such as e.g. heat...... generation and local material deformation (often referred to as flow) during the welding process itself. ii) Prediction of the residual stresses that will be present in the joint structure post to welding. While the former in general will call for a fully-coupled thermomechanical procedure, however...... for the FSW process at hand, the heat generation must either be prescribed analytically or based on a fully coupled analysis of the welding process itself. Along this line, a recently proposed thermal-pseudo-mechanical model is presented in which the temperature dependent yield stress of the weld material...

  9. Effects of thermomechanical processing on titanium aluminide strip cast by the melt overflow process

    Energy Technology Data Exchange (ETDEWEB)

    Gaspar, T.A. (Ribbon Technology Corporation, PO Box 30758, Columbus, OH 43230 (United States)); Hackman, L.E. (Ribbon Technology Corporation, PO Box 30758, Columbus, OH 43230 (United States)); Batawi, E. (Sulzer-Innotec, Division 1511, PO Box 65, Winterthur 8404 (Switzerland)); Peters, J.A. (Sulzer-Innotec, Division 1511, PO Box 65, Winterthur 8404 (Switzerland))

    1994-05-01

    The objective of this research project was to investigate the feasibility of producing titanium aluminide foils from direct cast strip using ribbon technology''s plasma melt overflow process. Niobium-modified Ti[sub 3]Al alloys were melted in a cold copper crucible using a transferred plasma arc and then direct cast into strip on a rotating chill roll.Samples cut from the as-cast Ti[sub 3]Al-Nb ([alpha][sub 2]) titanium aluminide strip were encapsulated into a pack. The packs were heated to the rolling temperature and then hot rolled at low strain rates. Foils 70 [mu]m (0.003 in) thick, having a uniform [alpha][sub 2]-B2 microstructure with oxygen contents as low as 900 wt.ppm were obtained after pack rolling. The strips and foils were characterized in terms of microstructure and chemical composition in the as-received, heat-treated and pack-rolled conditions.The results indicated that it was technically feasible to produce foils from direct cast titanium aluminide strip using pack-rolling technology. The advantage of this technology lies in its cost-effectiveness, since the relatively low cost direct-cast titanium aluminide strip was thermomechanically processed into foil with the desired microstructure without any intermediate processing steps. ((orig.))

  10. The influence of thermomechanical processing on microstructural evolution of Ti600 titanium alloy

    International Nuclear Information System (INIS)

    Han Yuanfei; Zeng Weidong; Qi Yunlian; Zhao Yongqing

    2011-01-01

    Highlights: → Temperature and strain rate have great influence on the microstructure features. → The formation of sub-grain and dislocation wall is the typically microstructure features observed in the β single-phase. → The elongated lamellar α platelets kinked increasingly and break up under the α + β processing conditions. → The softening mechanisms of the Ti600 alloy hot compressed at 1000-1100 deg. C are mainly dynamic recovery. - Abstract: The influences of thermomechanical processing on microstructural evolution of Ti600 alloy were studied in the temperature range of 800-1100 deg. C, and at the strain rate of 0.001-10 s -1 . During the isothermal compression experiment, the flow stress-strain curves are examined in the β single-phase and in the α + β two-phase regions. The results show that the thermomechanical processing parameters have significant influences on the microstructure of Ti600 alloy, especially on the grain size, morphologies of α phase. Moreover, the microstructural evolution was analyzed by optical microstructure (OM) and transmission electron microscopy (TEM). It was found that typical of dynamic recovery and dynamic recrystallization phenomenon occurring in the thermomechanical processing. These results will optimize the microstructural control for hot working of Ti600 alloy and deepen the understanding of the flow softening mechanism of near-α titanium alloy.

  11. Comparison of Diafiltration and Size-Exclusion Chromatography to Recover Hemicelluloses From Process Water From Thermomechanical Pulping of Spruce

    Science.gov (United States)

    Andersson, Alexandra; Persson, Tobias; Zacchi, Guido; Stålbrand, Henrik; Jönsson, Ann-Sofi

    Hemicelluloses constitute one of the most abundant renewable resources on earth. To increase their utilization, the isolation of hemicelluloses from industrial biomass side-streams would be beneficial. A method was investigated to isolate hemicelluloses from process water from a thermomechanical pulp mill. The method consists of three steps: removal of solids by microfiltration, preconcentration of the hemicelluloses by ultrafiltration, and purification by either size-exclusion chromatography (SEC) or diafiltration. The purpose of the final purification step is to separate hemicelluloses from small oligosaccharides, monosaccharides, and salts. The ratio between galactose, glucose, and mannose in oligo- and polysaccharides after preconcentration was 0.8∶1∶2.8, which is similar to that found in galactoglucomannan. Continuous diafiltration was performed using a composite fluoro polymer membrane with cutoff of 1000 Da. After diafiltration with four diavolumes the purity of the hemicelluloses was 77% (gram oligo- and polysaccharides/ gram total dissolved solids) and the recovery was 87%. Purification by SEC was performed with 5, 20, and 40% sample loadings, respectively and a flow rate of 12 or 25 mL/min (9 or 19 cm/h). The purity of hemicelluloses after SEC was approx 82%, and the recovery was above 99%. The optimal sample load and flow rate were 20% and 25 mL/min, respectively. The process water from thermomechanical pulping of spruce is inexpensive. Thus, the recovery of hemicelluloses is not of main importance. If the purity of 77%, obtained with diafiltration, is sufficient for the utilization of the hemicelluloses, diafiltration probably offers a less expensive alternative in this application.

  12. Grain size refinement of inconel 718 thermomechanical processing

    International Nuclear Information System (INIS)

    Okimoto, P.C.

    1988-01-01

    Inconel 718 is a Ni-Fe precipitation treated superalloy. It presents good thermal fatigue properties when the material has small grain size. The aim of this work is to study the grain size refinement by thermomechanical processing, through observations of the microstructural evolution and the influence of some of the process variables in the final grain size. The results have shown that this refinement occured by static recrystallization. The presence of precipitates have influenced the final grain size if the deformations are below 60%. For greater deformations the grain size is independent of the precipitate distribution in the matrix and tends to a limit size of 5 μm. (author)

  13. THERMO-MECHANICALLY PROCESSED ROLLED WIRE FOR HIGH-STRENGTH ON-BOARD WIRE

    Directory of Open Access Journals (Sweden)

    V. A. Lutsenko

    2011-01-01

    Full Text Available It is shown that at twisting of wire of diameter 1,83 mm, produced by direct wire drawing of thermomechanically processed rolled wire of diameter 5,5 mm of steel 90, metal stratification is completely eliminated at decrease of carbon, manganese and an additional alloying of chrome.

  14. Development of ultrafine ferritic sheaves/plates in SAE 52100 steel for enhancement of strength by controlled thermomechanical processing

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, J. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur, W.B. 721 302 (India); Scientific Services and Research and Development, Tata Steel, Jamshedpur 831 001, Jharkhand (India); Manna, I., E-mail: imanna@metal.iitkgp.ernet.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur, W.B. 721 302 (India); Central Glass and Ceramic Research Institute (CGCRI), Council of Scientific and Industrial Research (CSIR), 196 Raja S C Mullick Road, Jadavpur, Kolkata 700032 (India)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Ultrafine bainite + martensite duplex microstructure developed in SAE 52100 steel. Black-Right-Pointing-Pointer Thermomechanical processing modifies size + morphology of bainitic ferrite. Black-Right-Pointing-Pointer Processing involves hot deformation prior to/during/after austenitizing. Black-Right-Pointing-Pointer Significant improvement in mechanical strength achieved. Black-Right-Pointing-Pointer Similar study on high carbon, low alloy steel not reported in the literature. - Abstract: The present study attempts to tailor the size, morphology and distribution of the ferrite needles/sheaves by thermomechanical processing and develop an ultrafine ferrite + martensite duplex microstructure for enhancement of strength and toughness in SAE 52100 steel. The thermo-mechanical routine included 5% hot deformation before, during or after austenitizing at 950 Degree-Sign C for 15 min followed by austempering at 270 Degree-Sign C for 30 min and subsequent water quenching to room temperature. Optical/electron microscopy along with X-ray diffraction was used to quantitatively monitor the size, morphology and distribution of the phase or phase aggregate. Significant improvement in nanohardness, wear resistance and elastic modulus and was observed in samples subjected to thermomechanical processing, as compared to that following the same austenitizing and austempering routine without hot deformation at any stage. However, improvement in the bulk mechanical property due to the present thermo-mechanical is lower than that obtained in our earlier study comprising cold deformation prior to austenitizing and austempering.

  15. Microstructural stability and thermomechanical processing of boron modified beta titanium alloys

    Science.gov (United States)

    Cherukuri, Balakrishna

    One of the main objectives during primary processing of titanium alloys is to reduce the prior beta grain size. Producing an ingot with smaller prior beta grain size could potentially eliminate some primary processing steps and thus reduce processing cost. Trace additions of boron have been shown to decrease the as-cast grain size in alpha + beta titanium alloys. The primary focus of this dissertation is to investigate the effect of boron on microstructural stability and thermomechanical processing in beta titanium alloys. Two metastable beta titanium alloys: Ti-15Mo-2.6Nb-3Al-0.2Si (Beta21S) and Ti-5Al-5V-5Mo-3Cr (Ti5553) with 0.1 wt% B and without boron additions were used in this investigation. Significant grain refinement of the as-cast microstructure and precipitation of TiB whiskers along the grain boundaries was observed with boron additions. Beta21S and Beta21S-0.1B alloys were annealed above the beta transus temperature for different times to investigate the effect of boron on grain size stability. The TiB precipitates were very effective in restricting the beta grain boundary mobility by Zener pinning. A model has been developed to predict the maximum grain size as a function of TiB size, orientation, and volume fraction. Good agreement was obtained between model predictions and experimental results. Beta21S alloys were solution treated and aged for different times at several temperatures below the beta transus to study the kinetics of alpha precipitation. Though the TiB phase did not provide any additional nucleation sites for alpha precipitation, the grain refinement obtained by boron additions resulted in accelerated aging. An investigation of the thermomechanical processing behavior showed different deformation mechanisms above the beta transus temperature. The non-boron containing alloys showed a non-uniform and fine recrystallized necklace structure at grain boundaries whereas uniform intragranular recrystallization was observed in boron containing

  16. Thermo-mechanical process for treatment of welds

    International Nuclear Information System (INIS)

    Malik, R.K.

    1980-03-01

    Benefits from thermo-mechanical processing (TMP) of austenitic stainless steel weldments, analogous to hot isostatic pressing (HIP) of castings, most likely result from compressive plastic deformation, enhanced diffusion, and/or increased dislocation density. TMP improves ultrasonic inspectability of austenitic stainless steel welds owing to: conversion of cast dendrites into equiaxed austenitic grains, reduction in size and number of stringers and inclusions, and reduction of delta ferrite content. TMP induces structural homogenization and healing of void-type defects and thus contributes to an increase in elongation, impact strength, and fracture toughness as well as a significant reduction in data scatter for these properties. An optimum temperature for TMP or HIP of welds is one which causes negligible grain growth and an acceptable reduction in yield strength, and permits healing of porosity

  17. Influence of thermo-mechanical processing on the microstructure of Cu-based shape memory alloys produced by powder metallurgy

    International Nuclear Information System (INIS)

    Rodriguez, P.P.; Ibarra, A.; Iza-Mendia, A.; Recarte, V.; Perez-Landazabal, J.I.; San Juan, J.; No, M.L.

    2003-01-01

    Cu-Al-Ni shape memory alloys processed by powder metallurgy show very good thermo-mechanical properties, much better than those found in alloys produced by conventional casting. In this paper, we present the microstructural characterisation of these powder metallurgy alloys in order to find the microscopic mechanisms, linked to the powder metallurgy processing method, which are indeed responsible of such good thermo-mechanical behaviour. Electron microscopy studies [scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM)] show that powder metallurgy processing creates a sub-grain structure characterised by the presence of low angle sub-boundaries. These sub-boundaries are found to be lying on {1 1 0} and {1 1 2} lattice planes and are composed by an arrangement of superdislocations. These sub-boundaries may improve ductility in two ways: acting as a sink of dislocations which promotes plastic deformation and decreasing stress concentration at grain boundaries. Moreover, since sub-boundaries act as weak obstacles for the movement of martensite plates, the improvement on ductility is accomplished by an adequate thermo-mechanical behaviour

  18. Enhancement of the electrochemical behaviour and biological performance of Ti–25Ta–5Zr alloy by thermo-mechanical processing

    Energy Technology Data Exchange (ETDEWEB)

    Cimpean, Anisoara [Department of Biochemistry and Molecular Biology, University of Bucharest, Spl. Independentei, 91-95, 050095 Bucharest (Romania); Vasilescu, Ecaterina; Drob, Paula [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Cinca, Ion, E-mail: ion_cinca@hotmail.com [Faculty of Material Science and Engineering, Politehnica University, Spl. Independentei 313, 060042 Bucharest (Romania); Vasilescu, Cora; Anastasescu, Mihai [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Mitran, Valentina [Department of Biochemistry and Molecular Biology, University of Bucharest, Spl. Independentei, 91-95, 050095 Bucharest (Romania); Drob, Silviu Iulian [Department of Electrochemistry and Corrosion, Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania)

    2014-05-01

    A new Ti–25Ta–5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer–Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti–25Ta–5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances. - Highlights: • Ti–25Ta–5Zr alloy exhibited noble electrochemical, passive behaviour in simulated biofluids. • An electric equivalent circuit with two time constants was modelled. • Corrosion rates show the lowest values for the recrystallized Ti–25Ta–5Zr alloy. • In vitro tests revealed good cytocompatibility of as-cast and processed alloy. • Recrystallized treatment endows the alloy with superior biological performances.

  19. Enhancement of the electrochemical behaviour and biological performance of Ti–25Ta–5Zr alloy by thermo-mechanical processing

    International Nuclear Information System (INIS)

    Cimpean, Anisoara; Vasilescu, Ecaterina; Drob, Paula; Cinca, Ion; Vasilescu, Cora; Anastasescu, Mihai; Mitran, Valentina; Drob, Silviu Iulian

    2014-01-01

    A new Ti–25Ta–5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer–Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti–25Ta–5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances. - Highlights: • Ti–25Ta–5Zr alloy exhibited noble electrochemical, passive behaviour in simulated biofluids. • An electric equivalent circuit with two time constants was modelled. • Corrosion rates show the lowest values for the recrystallized Ti–25Ta–5Zr alloy. • In vitro tests revealed good cytocompatibility of as-cast and processed alloy. • Recrystallized treatment endows the alloy with superior biological performances

  20. Thermo-mechanical processing of a Ti 49.5Al 1.25Ag alloy

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, A.; Viana, F.; Vieira, M.F.; Santos, H.M.C. [GMM/IMAT, Dept. de Engenharia Metalurgica e de Materiais, FEUP, Porto (Portugal)

    2002-07-01

    Gamma titanium aluminide is an important candidate to several applications in the aerospace and automotive industries. The great drawback of these alloys is its low ductility at room temperature. This work is part of a study that intends to increase the ductility of gamma titanium aluminide through the addition of alloying elements. In this paper the effects of the heat treatment and the deformation processing on the microstructure of a Ti 49.5Al 1.25Ag are described. The alloy was produced by arc melting, under an argon atmosphere, using a water-cooled copper crucible. The as-cast samples were heat treated at 1300 and 1400 C. Encapsulated samples were deformed by double forging and multiple step rolling. The as-cast {gamma}-TiAl alloy presented an extended degree of segregation, have been detected three microconstituents: lamellar dendrites, interdendritic Al enriched {gamma}-phase and a number of Ag rich particles located at the dendritic/interdendritic interface. The heat treatment at 1400 C for 6 hours allowed the elimination of the as-cast microstructure and its replacement by a fully lamellar one. The thermomechanical processing produced non-homogenous microstructures of deformed lamellar grains and recrystallized gamma grains. The microstructure changes occurring during the several stages of the processing were characterized using optical and scanning electron microscopy. The modification of the chemical composition of the phases was determined using SEM-EDS facilities. (orig.)

  1. Thermo-mechanical modeling of the obduction process based on the Oman ophiolite case

    OpenAIRE

    Duretz , Thibault; Agard , Philippe; Yamato , Philippe; Ducassou , Céline; Burov , Evgenii ,; Gerya , T. V.

    2016-01-01

    International audience; Obduction emplaces regional-scale fragments of oceanic lithosphere (ophiolites) over continental lithosphere margins of much lower density. For this reason, the mechanisms responsible for obduction remain enigmatic in the framework of plate tectonics. We present two-dimensional (2D) thermo-mechanical models of obduction and investigate possible dynamics and physical controls of this process. Model geometry and boundary conditions are based on available geological and g...

  2. Characterization of Irreversible Fouling after Ultrafiltration of Thermomechanical Pulp Mill Process Water

    DEFF Research Database (Denmark)

    Thuvander, Johan; Zarebska, Agata; Hélix-Nielsen, Claus

    2018-01-01

    process streams is fouling of the membranes. Fouling not only increases operating costs but also reduces the operating time of the membrane plant. When optimizing the membrane cleaning method, it is important to know which compounds cause the fouling. In this work fouling of an ultrafiltration membrane...... was studied. The fouling propensity of untreated process water and microfiltrated process water was compared. Fouled membranes were analyzed using scanning electron microscopy and attenuated total reflection Fourier transform infrared spectrometry. Acid hydrolysis of membranes exposed to untreated process......Large volumes of wastewater with dissolved wood components are treated in wastewater treatment plants at thermomechanical pulp mills. It has been shown previously that hemicelluloses in these wastewater streams can be recovered by membrane filtration. A serious obstacle when treating lignocellulose...

  3. Experimental investigations on the state of the friction-welded joint zone in steel hybrid components after process-relevant thermo-mechanical loadings

    Science.gov (United States)

    Behrens, B.-A.; Bouguecha, A.; Vucetic, M.; Peshekhodov, I.; Matthias, T.; Kolbasnikov, N.; Sokolov, S.; Ganin, S.

    2016-10-01

    As a part of the newly established Collaborative Research Center 1153 (SFB 1153) "Process chain for the manufacturing of hybrid high-performance components by tailored forming" at the Leibniz Universität Hannover, the Institute of Forming Technology and Machines (IFUM) examines the influence of thermo-mechanical stresses on the reduced Young's modulus as well as the hardness of hybrid (steel-steel compound) joined semi-finished products. Currently the expertise in the production of bulk metal formed parts is limited to mono-materials. For manufacturing parts of hybrid materials and also for the methods of the new process routes, practical experience has to be gained. The subproject C1 within the collaborative research center 1153 with the short title "Failure Prediction" deals with the question, if the hybrid semi-finished products fulfill the thermo-mechanical demands or if they fail at the joining zone (JZ) during forging. For this purpose, stresses similar to those in the process were imposed on hybrid semi-finished products by torsion tests by using the thermo-mechanical test system Gleeble 3800. Afterwards, the specimens were examined metallographically and by nanoindentations with the help of a TriboIndenter TI950. Thus, first knowledge on the behaviour of thermo-mechanical stresses on the reduced Young's modulus and the hardness of hybrid joined semi-finished parts was gained.

  4. Optimization in Friction Stir Welding - With Emphasis on Thermo-mechanical Aspects

    DEFF Research Database (Denmark)

    Tutum, Cem Celal

    combined with classical single-objective and evolutionary multi-objective optimization algorithms (i.e. SQP and NSGA-II), to find the optimum process parameters (heat input, rotational and traverse welding speeds) that would result in favorable thermo-mechanical conditions for the process.......This book deals with the challenging multidisciplinary task of combining variant thermal and thermo-mechanical simulations for the manufacturing process of friction stir welding (FSW) with numerical optimization techniques in the search for optimal process parameters. The FSW process...... is characterized by multiphysics involving solid material flow, heat transfer, thermal softening, recrystallization and the formation of residual stresses. Initially, the thermal models were addressed since they in essence constitute the basis of all other models of FSW. Following this, several integrated thermo-mechanical...

  5. Mechanical properties of thermomechanical treated hyper-eutectic Al-Si-(Fe, Mn, Cu) materials

    OpenAIRE

    Umezawa, Osamu

    2005-01-01

    Tensile and high-cycle fatigue behavior of thermomechanical treated hyper-eutectic Al-Si-(Fe, Mn, Cu) materials were studied. Through the repeated thermomechanical treatment (RTMT) which is a repeat of the multi steps cold-working followed by heat treatment, Si crystals and/or intermetallic compounds were broken into some fragments and dispersed in the aluminum matrix. Fine dispersion of the second phase particles exhibited good ductility, since early fracture was overcome. A few large Si cry...

  6. A Study of the Effect of Interrupted Quenches on a Thermomechanically Processed High Carbon Steel.

    Science.gov (United States)

    1982-10-01

    steel . Successful martempering requires a cooling rate sufficient to avoid the nose of the C- curve and thus prevent significant bainite formation. When...STUDY OF THE EFFECT OF INTERRUPTED QUENCHES ON A THERMONECHANICALLY PROCESSED HIGH CARBON STEEL by Steven A. Barton October 1982 Thesis Advisor: T.R...unlimited. A Study of the Effect of Interrupted Quenches on a Thermomechanically Processed High Carbon Steel by Steven A. Barton Lieutenant, United

  7. High strength and high electrical conductivity Cu–Cr system alloys manufactured by hot rolling–quenching process and thermomechanical treatments

    International Nuclear Information System (INIS)

    Xia Chengdong; Zhang Wan; Kang Zhanyuan; Jia Yanlin; Wu Yifeng; Zhang Rui; Xu Genying; Wang Mingpu

    2012-01-01

    Highlights: ► HR–Q and thermomechanical treatments are successfully developed to manufacture Cu–Cr system alloys. ► Ordered fcc structure Cr precipitates are considered to be precursors of equilibrium bcc Cr precipitates. ► The Cr precipitates are responsible for the improvement of properties. ► Additions of Zr, Mg and Si bring about significant improvement in properties of Cu–Cr alloy. ► Good properties are ascribed to grain boundary strengthening, strain hardening and precipitation hardening. - Abstract: Cu–Cr system alloy strips were manufactured by an online hot rolling–quenching (HR–Q) process and subsequent thermomechanical treatments. The microstructure and properties of the alloys were investigated by observations of optical microscopy and transmission electron microscopy, and measurements of microhardness and electrical conductivity. The results show that the HR–Q process and thermomechanical treatments are successfully developed to manufacture Cu–Cr system alloy strips with good combinations of strength, conductivity and softening resistance. Ordered fcc structure Cr precipitates, which are decomposed from the thermomechanical treated alloys, are considered to be precursors to the formation of equilibrium bcc Cr precipitates and responsible for the improvement of properties during near peak aging. Small additions of Zr, Mg and Si effectively improve the hardness and softening resistance of Cu–Cr alloy, and slightly reduce the electrical conductivity. The achievement of high strength and high electrical conductivity in the alloys is ascribed to the interactions of grain boundary strengthening, strain hardening and precipitation hardening.

  8. Microstructure evolution and mechanical properties of T15 high speed steel prepared by twin-atomiser spray forming and thermo-mechanical processing

    International Nuclear Information System (INIS)

    Zhang, Guoqing; Yuan, Hua; Jiao, Dongling; Li, Zhou; Zhang, Yong; Liu, Zhongwu

    2012-01-01

    Spray formed T15 high speed steel (HSS) billets were deposited using a state-of-the-art twin-atomiser spray forming facility. The effects of post thermo-mechanical processing (hot isostatic pressing and hot forging) and heat treatment on the microstructure and mechanical properties were investigated. As-deposited billet has a density over 99.3% of the theoretical value and no measurable macro-segregation was observed. The microstructure consists of the equiaxed grains with mean size of ∼18 μm and MC- and M 6 C-type carbides non-uniformly distributed inside the grains and along the grain boundaries. After optimal thermo-mechanical processing and heat treatment, the microstructure was composed of equiaxed fine tempered martensites, and refined M 6 C and MC spherical carbides particles uniformly distributed along the grain boundaries and inside the grains. The hardness reached HRC68 after thermo-mechanical processing, and the corresponding impact toughness and bending strength reached 27 J/cm 2 and 4600 MPa respectively. Although HIP cannot increase the bending strength significantly, it can effectively improve the impact toughness through refining and globurizing carbides.

  9. Concurrent material-fabrication optimization of metal-matrix laminates under thermo-mechanical loading

    Science.gov (United States)

    Saravanos, D. A.; Morel, M. R.; Chamis, C. C.

    1991-01-01

    A methodology is developed to tailor fabrication and material parameters of metal-matrix laminates for maximum loading capacity under thermomechanical loads. The stresses during the thermomechanical response are minimized subject to failure constrains and bounds on the laminate properties. The thermomechanical response of the laminate is simulated using nonlinear composite mechanics. Evaluations of the method on a graphite/copper symmetric cross-ply laminate were performed. The cross-ply laminate required different optimum fabrication procedures than a unidirectional composite. Also, the consideration of the thermomechanical cycle had a significant effect on the predicted optimal process.

  10. Tungsten - rhenium alloys wire: overview of thermomechanical processing and properties data

    International Nuclear Information System (INIS)

    Bryskin, B.

    2001-01-01

    The scope of this study encompasses the compositional modifications of the tungsten-rhenium dual system (W-3/5 Re up to W-27 Re) as well as some of the tungsten-molybdenum-rhenium ternary system. The alloys of interest are considered with a specific representation of powder metallurgy route based on doped or undoped tungsten vs. vacuum melted materials. This paper constitutes an in-depth review of structural and mechanical properties and systematic compilation of challenges necessary to provide the quality consistency of severely drawn filaments. The issue of thermomechanical processing trends is addressed as an important part of W-Re fabrication technology to achieve further improvement in design properties of rod and wire. (author)

  11. Investigation of multi-stage cold forward extrusion process using coupled thermo-mechanical finite element analysis

    Science.gov (United States)

    Görtan, Mehmet Okan

    2018-05-01

    Cold extrusion processes are distinguished by their low material usage as well as great efficiency in the production of mid-range and large component series. Although majority of the cold extruded parts are produced using die systems containing multiple forming stages, this subject has rarely been investigated so far. Therefore, the characteristics of multi-stage cold forward rod extrusion is studied in the current work using thermo-mechanically coupled finite element (FE) analysis. A case hardening steel, 16MnCr5 (1.7131) was used as experimental material. Its strain, strain rate and temperature dependent mechanical characteristics were determined using compression testing and modeled in FE simulations via a Johnson-Cook material model. Friction coefficients for the same material while in contact with a tool steel (1.2379) were determined dependent on temperature and contact pressure using sliding compression test (SCT) and modeled by an adaptive friction model developed by the author. In the first set of simulations, rod material with a diameter of 14.9 mm was extruded down to a diameter of 9.6 mm in a single step using three different die opening angles (2α); 20°, 40° and 60°. In the second set of investigations, the same rod was reduced first to 12 mm and then to 9.6 mm in two steps within the same forming die. Press forces, contact normal stresses between extruded material and forming die, material temperature and axial stresses are compared in these two set of simulations and the differences are discussed.

  12. Simulation of thermo-mechanical effect in bulk-silicon FinFETs

    OpenAIRE

    Burenkov, Alex; Lorenz, Jürgen

    2016-01-01

    The thermo-mechanical effect in bulk-silicon FinFETs of the 14 nm CMOS technology node is studied by means of numerical simulation. The electrical performance of such devices is significantly enhanced by the intentional introduction of mechanical stress during the device processing. The thermo-mechanical effect modifies the mechanical stress distribution in active regions of the transistors when they are heated. This can lead to a modification of the electrical performance. Numerical simulati...

  13. Blanket Manufacturing Technologies : Thermomechanical Tests on HCLL Blanket Mocks Up

    International Nuclear Information System (INIS)

    Laffont, G.; Cachon, L.; Taraud, P.; Challet, F.; Rampal, G.; Salavy, J.F.

    2006-01-01

    In the Helium Cooled Lithium Lead (HCLL) Blanket concept, the lithium lead plays the double role of breeder and multiplier material, and the helium is used as coolant. The HCCL Blanket Module are made of steel boxes reinforced by stiffening plates. These stiffening plates form cells in which the breeder is slowly flowing. The power deposited in the breeder material is recovered by the breeder cooling units constituted by 5 parallel cooling plates. All the structures such as first wall, stiffening and cooling plates are cooled by helium. Due to the complex geometry of these parts and the high level of pressure and temperature loading, thermo-mechanical phenomena expected in the '' HCLL blanket concept '' have motivated the present study. The aim of this study, carried out in the frame of EFDA Work program, is to validate the manufacturing technologies of HCLL blanket module by testing small scale mock-up under breeder blanket representative operating conditions.The first step of this experimental program is the design and manufacturing of a relevant test section in the DIADEMO facility, which was recently upgraded with an He cooling loop (pressure of 80 bar, maximum temperature of 500 o C,flow rate of 30 g/s) taking the opportunity of synergies with the gas-cooled fission reactor R-and-D program. The second step will deal with the thermo-mechanical tests. This paper focuses on the program made to support the cooling plate mock up tests which will be carried out on the DIADEMO facility (CEA) by thermo-mechanical calculations in order to define the relevant test conditions and the experimental parameters to be monitored. (author)

  14. Development and Characterization of Improved NiTiPd High-Temperature Shape-Memory Alloys by Solid-Solution Strengthening and Thermomechanical Processing

    Science.gov (United States)

    Bigelow, Glen; Noebe, Ronald; Padula, Santo, II; Garg, Anita; Olson, David

    2006-01-01

    The need for compact, solid-state actuation systems for use in the aerospace, automotive, and other transportation industries is currently motivating research in high-temperature shape-memory alloys (HTSMA) with transformation temperatures greater than 100 C. One of the basic high-temperature alloys investigated to fill this need is Ni(19.5)Ti(50.5)Pd30. Initial testing has indicated that this alloy, while having acceptable work characteristics, suffers from significant permanent deformation (or ratcheting) during thermal cycling under load. In an effort to overcome this deficiency, various solid-solution alloying and thermomechanical processing schemes were investigated. Solid-solution strengthening was achieved by substituting 5at% gold or platinum for palladium in Ni(19.5)Ti(50.5)Pd30, the so-called baseline alloy, to strengthen the martensite and austenite phases against slip processes and improve thermomechanical behavior. Tensile properties, work behavior, and dimensional stability during repeated thermal cycling under load for the ternary and quaternary alloys were compared. The relative difference in yield strength between the martensite and austenite phases and the dimensional stability of the alloy were improved by the quaternary additions, while work output was only minimally impacted. The three alloys were also thermomechanically processed by cycling repeatedly through the transformation range under a constant stress. This so-called training process dramatically improved the dimensional stability in these samples and also recovered the slight decrease in work output caused by quaternary alloying. An added benefit of the solid-solution strengthening was maintenance of enhanced dimensional stability of the trained material to higher temperatures compared to the baseline alloy, providing a greater measure of over-temperature capability.

  15. Modelling the Thermomechanical Conditions in Friction Stir Welding

    DEFF Research Database (Denmark)

    Schmidt, Henrik Nikolaj Blich

    Friction Stir Welding is a solid-state welding process invented by TWI in 1991. The FSW process is unique in the sense that joining of un-weldable alloys readily can be made. The thermomechanical conditions present in the workpiece during the welding process are of great interest since...... these control the properties of the weld. In the present work, a set of experimental, analytical and numerical analyses are carried out in order to evaluate the thermomechanical conditions descriptive for welding of aluminium, in this case AA2024-T3, under a specific set of welding parameters. Despite...... these specific data, the developed models can be applied for other alloys and welding parameters as well. A detailed experiment is carried out which constitutes the basis for the development and validation of the numerical and analytical models presented in this work. The contact condition at the tool...

  16. Finding an Optimal Thermo-Mechanical Processing Scheme for a Gum-Type Ti-Nb-Zr-Fe-O Alloy

    Science.gov (United States)

    Nocivin, Anna; Cojocaru, Vasile Danut; Raducanu, Doina; Cinca, Ion; Angelescu, Maria Lucia; Dan, Ioan; Serban, Nicolae; Cojocaru, Mirela

    2017-09-01

    A gum-type alloy was subjected to a thermo-mechanical processing scheme to establish a suitable process for obtaining superior structural and behavioural characteristics. Three processes were proposed: a homogenization treatment, a cold-rolling process and a solution treatment with three heating temperatures: 1073 K (800 °C), 1173 K (900 °C) and 1273 K (1000 °C). Results of all three proposed processes were analyzed using x-ray diffraction and scanning electron microscopy imaging, to establish and compare the structural modifications. The behavioural status was completed with micro-hardness and tensile strength tests. The optimal results were obtained for solution treatment at 1073 K.

  17. Effect of Different Thermomechanical Processes on the Microstructure, Texture, and Mechanical Properties of API 5L X70 Steel

    Science.gov (United States)

    Masoumi, Mohammad; Echeverri, Edwan Anderson Ariza; Silva, Cleiton Carvalho; Béreš, Miloslav; de Abreu, Hamilton Ferreira Gomes

    2018-03-01

    A commercial API 5L X70 steel plate was subjected to different thermomechanical processes to propose a novel thermomechanical rolling path to achieve improved mechanical properties. Scanning electron microscopy, electron backscatter diffraction, and x-ray texture analysis were employed for microstructural characterization. The results showed that strain-free recrystallized {001} ferrite grains that developed at higher rolling temperature could not meet the American Petroleum Institute (API) requirements. Also, refined and work-hardened grains that have formed in the intercritical region with high stored energy do not provide suitable tensile properties. However, fine martensite-austenite constituents dispersed in ferrite matrix with grains having predominantly {111} and {110} orientations parallel to the normal direction that developed under isothermal rolling at 850 °C provided an outstanding combination of tensile strength and ductility.

  18. A thermomechanical crystal plasticity constitutive model for ultrasonic consolidation

    KAUST Repository

    Siddiq, Amir; El Sayed, Tamer S.

    2012-01-01

    We present a micromechanics-based thermomechanical constitutive model to simulate the ultrasonic consolidation process. Model parameters are calibrated using an inverse modeling approach. A comparison of the simulated response and experimental

  19. Thermomechanical Response of Self-Assembled Nanoparticle Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yifan [Department; James; Chan, Henry [Center; Narayanan, Badri [Center; McBride, Sean P. [Department; Sankaranarayanan, Subramanian K. R. S. [Center; Lin, Xiao-Min [Center; Jaeger, Heinrich M. [Department; James

    2017-07-21

    Monolayers composed of colloidal nanoparticles, with a thickness of less than 10 nm, have remarkable mechanical moduli and can suspend over micrometer-sized holes to form free-standing membranes. In this paper, we discuss experiment's and coarse-grained molecular dynamics simulations characterizing the thermomechanical properties of these self-assembled nanoparticle membranes. These membranes remain strong and resilient up to temperatures much higher than previous simulation predictions and exhibit an unexpected hysteretic behavior during the first heating cooling cycle. We show this hysteretic behavior can be explained by an asymmetric ligand configuration from the self assembly process and can be controlled by changing the ligand coverage or cross-linking the ligand molecules. Finally, we show the screening effect of water molecules on the ligand interactions can strongly affect the moduli and thermomechanical behavior.

  20. The Effect of Thermo-mechanical Processing on the Ballistic Limit Velocity of Extra Low Interstitial Titanium Alloy Ti-6AL- 4V

    National Research Council Canada - National Science Library

    Burkins, Matthew

    2000-01-01

    .... Department of Energy's Albany Research Center (ARC) performed a joint research program to evaluate the effect of thermo-mechanical processing on the ballistic limit velocity for an extra-low interstitial grade of the titanium alloy Ti-6Al-4V...

  1. Effects of thermomechanical processing on microstructure and properties of bainitic work hardening steel

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Jie, E-mail: caojie910@ahut.edu.cn [School of Metallurgical Engineering, Anhui University of Technology, Ma’anshan 243002 (China); Yan, Jun; Zhang, Jing [School of Metallurgical Engineering, Anhui University of Technology, Ma’anshan 243002 (China); Yu, Tongren [Technology Center, Maanshan Iron & Steel Company Limited, Ma’anshan 243000 (China)

    2015-07-15

    The thermomechanical processing (TMP) of a bainitic work hardening steel was carried out on a Gleeble3500 simulator. The microstructure of processed specimens was investigated by means of optical and electron microscopy, and tensile tests were performed in a ZwickRoell tensile tester. The deformation temperatures of austenite varied from 800 °C to 900 °C. The cooling methods include single rate cooling method and two-stage cooling method. The two-stage cooling method includes fast cooling rates ranging from 4 °C/s to 12 °C/s and slow cooling rates ranging from 1 °C/s to 2 °C/s. It is shown that, within the range of parameters tested, the obtained microstructures are granular bainite, the tensile strength of the steel can be adjusted from 897.8 MPa to 1083.2 MPa, and good plasticity can be obtained at different strength levels.

  2. A study of thermo-mechanical stress and its impact on through-silicon vias

    International Nuclear Information System (INIS)

    Ranganathan, N; Balasubramanian, N; Prasad, K; Pey, K L

    2008-01-01

    The BOSCH etch process, which is commonly used in microelectromechanical system fabrication, has been extensively investigated in this work for implementation in through-silicon via (TSV) technology for 3D-microsystems packaging. The present work focuses on thermo-mechanical stresses caused by thermal loading due to post-TSV processes and their impact on the electrical performance of through-silicon copper interconnects. A test vehicle with deep silicon copper-plated comb structure was designed to study and evaluate different deep silicon via etch processes and its effect on the electrical leakage characteristics under various electrical and thermal stress conditions. It has been shown that the leakage current between the comb interconnect structures increases with an increase in sidewall roughness and that it can be significantly lowered by smoothening the sidewalls. It was also shown that by tailoring a non-BOSCH etch process with the normal BOSCH process, a similar leakage current reduction can be achieved. It was also shown through thermo-mechanical simulation studies that there is a clear correlation between high leakage current behavior due to non-uniform Ta barrier deposition over the rough sidewalls and the thermo-mechanical stress induced by post-TSV processes

  3. Improvement of Thermo-Mechanical Properties of Short Natural Fiber Reinforced Recycled Polypropylene Composites through Double Step Grafting Process

    Science.gov (United States)

    Saputra, O. A.; Rini, K. S.; Susanti, T. D.; Mustofa, R. E.; Prameswari, M. D.; Pramono, E.

    2017-07-01

    This study focused on the effect of a compatibilizer addition, maleic anhydrides (MAH) on mechanical, thermal and water absorption properties of oil palm empty fruit bunches (EFB) fiber reinforced recycled polypropylene (rPP) biocomposites. The double steps grafting process were conducted by incorporated MAH on both rPP and EFB to improve the surface adhesion between these materials, to result in a good mechanical properties as well as biocompatibility to nature. The chemical test was carried out using FTIR (Fourier Transform Infra-Red) spectroscopy technique to evaluated grafting process. The mechanical test was investigated and found that the addition of 10 phr MAH to both rPP and EFB improved mechanical strength of the biocomposites higher than another formulas. In this study, thermal properties of biocomposites also characterized. Water absorption (WA) analysis showed the presence of EFB fiber increased the water uptake of the material.

  4. Enhancing the ABAQUS Thermomechanics Code to Simulate Steady and Transient Fuel Rod Behavior

    International Nuclear Information System (INIS)

    Williamson, R.L.; Knoll, D.A.

    2009-01-01

    A powerful multidimensional fuels performance capability, applicable to both steady and transient fuel behavior, is developed based on enhancements to the commercially available ABAQUS general-purpose thermomechanics code. Enhanced capabilities are described, including: UO2 temperature and burnup dependent thermal properties, solid and gaseous fission product swelling, fuel densification, fission gas release, cladding thermal and irradiation creep, cladding irradiation growth, gap heat transfer, and gap/plenum gas behavior during irradiation. The various modeling capabilities are demonstrated using a 2D axisymmetric analysis of the upper section of a simplified multi-pellet fuel rod, during both steady and transient operation. Computational results demonstrate the importance of a multidimensional fully-coupled thermomechanics treatment. Interestingly, many of the inherent deficiencies in existing fuel performance codes (e.g., 1D thermomechanics, loose thermo-mechanical coupling, separate steady and transient analysis, cumbersome pre- and post-processing) are, in fact, ABAQUS strengths.

  5. Thermomechanical DART code improvements for LEU VHD dispersion and monolithic fuel element analysis

    International Nuclear Information System (INIS)

    Taboada, H.; Saliba, R.; Moscarda, M.V.; Rest, J.

    2005-01-01

    A collaboration agreement between ANL/US DOE and CNEA Argentina in the area of Low Enriched Uranium Advanced Fuels has been in place since October 16, 1997 under the Implementation Arrangement for Technical Exchange and Cooperation in the Area of Peaceful Uses of Nuclear Energy. An annex concerning DART code optimization has been operative since February 8, 1999. Previously, as a part of this annex a visual FASTDART version and also a DART THERMAL version were presented during RERTR 2000, 2002 and RERTR 2003 Meetings. During this past year the following activities were completed: Optimization of DART TM code Al diffusion parameters by testing predictions against reliable data from RERTR experiments. Improvements on the 3-D thermo-mechanical version of the code for modeling the irradiation behavior of LEU U-Mo monolithic fuel. Concerning the first point, by means of an optimization of parameters of the Al diffusion through the interaction product theoretical expression, a reasonable agreement between DART temperature calculations with reliable RERTR PIE data was reached. The 3-D thermomechanical code complex is based upon a finite element thermal-elastic code named TERMELAS, and irradiation behavior provided by the DART code. An adequate and progressive process of coupling calculations of both codes at each time step is currently developed. Compatible thermal calculation between both codes was reached. This is the first stage to benchmark and validate against RERTR PIE data the coupling process. (author)

  6. A Numerical Model for the Thermomechanical Conditions During Hydration of Early-age Concrete

    DEFF Research Database (Denmark)

    Hattel, Jesper; Thorborg, Jesper

    2003-01-01

    In the present study, a macroscopic numerical model for the thermomechanical conditions during hydration of early-age concrete is presented. The formulation is based on a semi-coupled, incremental thermomechanical model where the heat production from the hydration process is expressed in terms...... of the maturity and the thermal activation is expressed by the Arrhenius principle. The material properties are assumed to depend on the hydration process via the maturity. The discretization of the governing equations is accomplished by a control volume formulation involving a time-splitting scheme for the heat...

  7. Research and Progress of Thermomechanical Treatment of Al-Li Alloys

    Directory of Open Access Journals (Sweden)

    WU Xiuliang

    2016-10-01

    Full Text Available The strengthening and toughening mechanism of aluminum lithium alloy treated by thermo-mechanical processing have been summarized, and the effect on the evolution of microstructures, grain structure and precipitation, were discussed and analysed deeply. The precipitation sequence and behavior of the main precipitation phase were modified by the thermo-mechanical processing, stimulating the forming of fine dispersion combined particles of δ',θ"/θ', T1, and S"/S' phases, uniformly distributed in the matrix, which significantly improved the relationships of strength and the plastic toughness, with the inhibiting of broadening of precipitate free zones, and of the precipitation and coarsening of strengthening particles at the grain boundary.The density of solute atom and vacancies significantly raised up after solution treating, and retained as supersaturated solid solution after water quenching, which acted as the driving force for the precipitation during subsequent aging. Pre-deformation and pre-aging significantly increased the density of fine dispersion strengthening particles of δ' and G.P. zones,which uniformly nucleated in the matrix, and the combined strengthening phases of δ',θ"/θ', and T1 were obtained after high temperature second aging, controlling the size and volume fraction of these particles.Refined grain and optimal grain structure were achieved by new and typical thermo-mechanical processing, and the proportion, size, and oriented relationship of main strengthening particles of δ',θ"/θ', and T1 phases were optimized.At last, the research direction of new thermo-mechanical treatment on the large scale rolled plates and hot worked forgings is pointed out, such as age forming, to meet the need of light high performance of new aluminum lithium alloys used for the large aircrafs and heavy lift launch vehicles.

  8. Thermo-mechanical ratcheting in jointed rock masses

    KAUST Repository

    Pasten, C.

    2015-09-01

    Thermo-mechanical coupling takes place in jointed rock masses subjected to large thermal oscillations. Examples range from exposed surfaces under daily and seasonal thermal fluctuations to subsurface rock masses affected by engineered systems such as geothermal operations. Experimental, numerical and analytical results show that thermo-mechanical coupling can lead to wedging and ratcheting mechanisms that result in deformation accumulation when the rock mass is subjected to a biased static-force condition. Analytical and numerical models help in identifying the parameter domain where thermo-mechanical ratcheting can take place.

  9. Thermo-mechanical ratcheting in jointed rock masses

    KAUST Repository

    Pasten, C.; Garcí a, M.; Santamarina, Carlos

    2015-01-01

    Thermo-mechanical coupling takes place in jointed rock masses subjected to large thermal oscillations. Examples range from exposed surfaces under daily and seasonal thermal fluctuations to subsurface rock masses affected by engineered systems such as geothermal operations. Experimental, numerical and analytical results show that thermo-mechanical coupling can lead to wedging and ratcheting mechanisms that result in deformation accumulation when the rock mass is subjected to a biased static-force condition. Analytical and numerical models help in identifying the parameter domain where thermo-mechanical ratcheting can take place.

  10. Thermomechanical Treatments on High Strength Al-Zn-Mg(-Cu) Alloys

    National Research Council Canada - National Science Library

    Di Russo, E; Conserva, M; Gatto, F

    1974-01-01

    An investigation was carried out to determine the metallurgical properties of Al-Zn-Mg and Al-Zn-Mg-Cu alloy products processed according to newly developed Final Thermomechanical Treatments (FTMT) of T-AHA type...

  11. Thermomechanical controls on magma supply and volcanic deformation: application to Aira caldera, Japan

    Science.gov (United States)

    Hickey, James; Gottsmann, Joachim; Nakamichi, Haruhisa; Iguchi, Masato

    2016-01-01

    Ground deformation often precedes volcanic eruptions, and results from complex interactions between source processes and the thermomechanical behaviour of surrounding rocks. Previous models aiming to constrain source processes were unable to include realistic mechanical and thermal rock properties, and the role of thermomechanical heterogeneity in magma accumulation was unclear. Here we show how spatio-temporal deformation and magma reservoir evolution are fundamentally controlled by three-dimensional thermomechanical heterogeneity. Using the example of continued inflation at Aira caldera, Japan, we demonstrate that magma is accumulating faster than it can be erupted, and the current uplift is approaching the level inferred prior to the violent 1914 Plinian eruption. Magma storage conditions coincide with estimates for the caldera-forming reservoir ~29,000 years ago, and the inferred magma supply rate indicates a ~130-year timeframe to amass enough magma to feed a future 1914-sized eruption. These new inferences are important for eruption forecasting and risk mitigation, and have significant implications for the interpretations of volcanic deformation worldwide. PMID:27619897

  12. Thermomechanical controls on magma supply and volcanic deformation: application to Aira caldera, Japan.

    Science.gov (United States)

    Hickey, James; Gottsmann, Joachim; Nakamichi, Haruhisa; Iguchi, Masato

    2016-09-13

    Ground deformation often precedes volcanic eruptions, and results from complex interactions between source processes and the thermomechanical behaviour of surrounding rocks. Previous models aiming to constrain source processes were unable to include realistic mechanical and thermal rock properties, and the role of thermomechanical heterogeneity in magma accumulation was unclear. Here we show how spatio-temporal deformation and magma reservoir evolution are fundamentally controlled by three-dimensional thermomechanical heterogeneity. Using the example of continued inflation at Aira caldera, Japan, we demonstrate that magma is accumulating faster than it can be erupted, and the current uplift is approaching the level inferred prior to the violent 1914 Plinian eruption. Magma storage conditions coincide with estimates for the caldera-forming reservoir ~29,000 years ago, and the inferred magma supply rate indicates a ~130-year timeframe to amass enough magma to feed a future 1914-sized eruption. These new inferences are important for eruption forecasting and risk mitigation, and have significant implications for the interpretations of volcanic deformation worldwide.

  13. Thermomechanical treatment of titanium alloys

    International Nuclear Information System (INIS)

    Khorev, A.K.

    1979-01-01

    The problems of the theory and practical application of thermomechanical treatment of titanium alloys are presented. On the basis of the systematic investigations developed are the methods of thermomechanical treatment of titanium alloys, established are the optimum procedures and produced are the bases of their industrial application with an account of alloy technological peculiarities and the procedure efficiency. It is found that those strengthening methods are more efficient at which the contribution of dispersion hardening prevails over the strengthening by phase hardening

  14. Improvement of thermo-mechanical properties of ceramic materials for nuclear applications

    International Nuclear Information System (INIS)

    Decroix, G.M.; Gosset, D.; Kryger, B.; Boussuge, M.; Burlet, H.

    1994-01-01

    In order to improve the thermo-mechanical properties of materials used as neutron absorbers in nuclear reactors, cermet or cercer have been produced with two original microstructures: micro- or macro-dispersed composites. The composites thermal shock resistance has been evaluated in an image furnace. The microstructures we obtained involve different reinforcement mechanisms, such as crack deflection, crack branching, crack bridging or microcrack toughening, and improvement of thermal conductivity. The results reveal a significant improvement of the thermo-mechanical properties of the boron base neutron absorbers whose fabrication process leads to a macro-dispersed microstructure. (authors). 8 refs., 8 figs., 2 tabs

  15. Investigation of cold extrusion process using coupled thermo-mechanical FEM analysis and adaptive friction modeling

    Science.gov (United States)

    Görtan, Mehmet Okan

    2017-10-01

    Cold extrusion processes are known for their excellent material usage as well as high efficiency in the production of large batches. Although the process starts at room temperature, workpiece temperatures may rise above 200°C. Moreover, contact normal stresses can exceed 2500 MPa, whereas surface enlargement values can reach up to 30. These changes affects friction coefficients in cold extrusion processes. In the current study, friction coefficients between a plain carbon steel C4C (1.0303) and a tool steel (1.2379) are determined dependent on temperature and contact pressure using the sliding compression test (SCT). In order to represent contact normal stress and temperature effects on friction coefficients, an empirical adaptive friction model has been proposed. The validity of the model has been tested with experiments and finite element simulations for a cold forward extrusion process. By using the proposed adaptive friction model together with thermo-mechanical analysis, the deviation in the process loads between numerical simulations and model experiments could be reduced from 18.6% to 3.3%.

  16. Microstructure development during thermomechanical treatment of Al-Mg-Si alloy

    Directory of Open Access Journals (Sweden)

    Martinova Z.

    2002-01-01

    Full Text Available The effect of natural aging and 95% cold deformation on the microstructure evolution and aging characteristics in commercial Al - 1 mass % Mg2Si alloy subjected to thermomechanical treatment (TMT was examined. Transmission electron microscopy observations, tensile tests and electrical conductivity measurements were carried out in order to correlate microstructural features to properties on each TMT step. It was established that pre-aging at room temperature affected the morphology of dislocation structure induced by next cold deformation. The observed transition from cellular to homogenous dislocation distribution was explained by the different stability of zones produced by pre-aging of different duration. Natural aging suppressed recovery processes during post-deformation artificial aging, especially after prolonged storage after quenching and at lower aging temperature. It influenced the morphology of precipitates produced by post deformation artificial aging also. The overall effect of TMT involving prior-deformation natural aging in the scheme, on hardness, tensile properties and electrical conductivity is discussed based on experimental microstruture observations.

  17. Nitrogen-containing steels and thermomechanical treatment

    International Nuclear Information System (INIS)

    Kaputkina, L.; Prokoshkina, V.G.; Svyazhin, G.

    2004-01-01

    The strengthening of nitrogen-containing corrosion-resistant steels resulting from alloying and thermomechanical treatment have been investigated using X-ray diffraction analysis, light microscopy, hardness measurements and tensile testing. Combined data have been obtained for nitrogen interaction with alloying elements , peculiarities of deformed structure and short-range of nitrogen-containing steels of various structural classes. The higher nitrogen and total alloying element contents, the higher deformation strengthening. Prospects of use the steels with not high nitrogen content and methods of their thermomechanical strengthening are shown. High temperature thermomechanical treatment (HTMT) is very effective for obtaining high and thermally stable constructional strength of nitrogen-containing steels of all classes. The HTMT is most effective if used in a combination with dispersion hardening for aging steels or in the case of mechanically unstable austenitic steels. (author)

  18. Heat treatments and thermomechanical cycling influences on the R-phase in Ti-Ni shape memory alloys

    Directory of Open Access Journals (Sweden)

    Cezar Henrique Gonzalez

    2010-09-01

    Full Text Available This article studies changes observed on the R-phase thermoelastic behavior in a near-equiatomic Ti-Ni shape memory alloy. Three kinds of procedures have been performed: different treatments, thermomechanical cycling under constant loading in shape memory helical springs and thermal cycling in as-treated and trained samples. Several heat treatments were carried out to investigate evolution of the R-phase by differential scanning calorimetry (DSC. A heat treatment was chosen on which R-phase is absent. Shape memory springs were produced and submitted to a training process in an apparatus by tensioning the springs under constant loading. Thermal cycling in DSC was realized in as-treated and trained samples. Several aspects of one-step (B2→B19' and two-steps (B2→R→B19' martensitic transformations and R-phase formation and their evolution during tests were observed and discussed.

  19. Thermomechanical processing of plasma sprayed intermetallic sheets

    Science.gov (United States)

    Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  20. Enhancing the ABAQUS thermomechanics code to simulate multipellet steady and transient LWR fuel rod behavior

    International Nuclear Information System (INIS)

    Williamson, R.L.

    2011-01-01

    Highlights: → The ABAQUS thermomechanics code is enhanced to enable simulation of nuclear fuel behavior. → Comparisons are made between discrete and smeared fuel pellet analysis. → Multidimensional and multipellet analysis is important for accurate prediction of PCMI. → Fully coupled thermomechanics results in very smooth prediction of fuel-clad gap closure. → A smeared-pellet approximation results in significant underprediction of clad radial displacements and plastic strain. - Abstract: A powerful multidimensional fuels performance analysis capability, applicable to both steady and transient fuel behavior, is developed based on enhancements to the commercially available ABAQUS general-purpose thermomechanics code. Enhanced capabilities are described, including: UO 2 temperature and burnup dependent thermal properties, solid and gaseous fission product swelling, fuel densification, fission gas release, cladding thermal and irradiation creep, cladding irradiation growth, gap heat transfer, and gap/plenum gas behavior during irradiation. This new capability is demonstrated using a 2D axisymmetric analysis of the upper section of a simplified multipellet fuel rod, during both steady and transient operation. Comparisons are made between discrete and smeared-pellet simulations. Computational results demonstrate the importance of a multidimensional, multipellet, fully-coupled thermomechanical approach. Interestingly, many of the inherent deficiencies in existing fuel performance codes (e.g., 1D thermomechanics, loose thermomechanical coupling, separate steady and transient analysis, cumbersome pre- and post-processing) are, in fact, ABAQUS strengths.

  1. Thermomechanical processing of In-containing β-type Ti-Nb alloys.

    Science.gov (United States)

    Pilz, Stefan; Geissler, David; Calin, Mariana; Eckert, Jürgen; Zimmermann, Martina; Freudenberger, Jens; Gebert, Annett

    2018-03-01

    In this study, the effect of thermomechanical processing on microstructure evolution of the indium-containing β-type Ti alloys (Ti-40Nb)-3.5In and (Ti-36Nb)-3.5In was examined. Both alloys show an increased β-phase stability compared to binary alloys due to In additions. This leads to a reduced α''-phase fraction in the solution treated and recrystallized state in the case of (Ti-36Nb)-3.5In and to the suppression of stress-induced α'' formation and deformation twinning for (Ti-40Nb)-3.5In. The mechanical properties of the alloys were subsequently studied by quasistatic tensile tests in the recrystallized state, revealing reduced Young's modulus values of 58GPa ((Ti-40Nb)-3.5In) and 56GPa ((Ti-36Nb)-3.5In) compared to 60GPa as determined for Ti-40Nb. For both In-containing alloys the ultimate tensile strength is in the range of 560MPa. Due to the suppressed α'' formation, (Ti-40Nb)-3.5In exhibits a linear elastic deformation behavior during tensile loading together with a low Young's modulus and is therefore promising for load-bearing implants. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Microstructure evolution and texture development in thermomechanically processed Mg-Li-Al based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod [Department of Materials Science and Engineering, IIT Kanpur (India); Govind [Vikram Sarabhai Space Center, Trivandrum (India); Shekhar, Rajiv; Balasubramaniam, R. [Department of Materials Science and Engineering, IIT Kanpur (India); Balani, Kantesh, E-mail: kbalani@iitk.ac.in [Department of Materials Science and Engineering, IIT Kanpur (India)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Thermomechanical processing of novel LAT 971 and LATZ 9531 Mg-Al-Li based alloys. Black-Right-Pointing-Pointer Microstructural deviation from the equilibrium phase diagram. Black-Right-Pointing-Pointer Disparity in texture of these alloys after hot-rolling (recrystallization and grain growth). Black-Right-Pointing-Pointer Role of alloying and phase distribution in affecting the texture/interplaner spacing. - Abstract: In the present study, the influence of alloying and thermomechanical processing on the microstructure and texture evolution on the two Mg-Li-Al based alloys, namely Mg-9 wt% Li-7 wt% Al-1 wt% Sn (LAT971) and Mg-9 wt% Li-5 wt% Al-3 wt% Sn-1 wt% Zn (LATZ9531) has been elicited. Novel Mg-Li-Al based alloys were cast (induction melting under protective atmosphere) followed by hot rolling at {approx}573 K with a cumulative reduction of five. A contrary dual phase dendritic microstructure rich in {alpha}-Mg, instead of {beta}-Li phase predicted by equilibrium phase diagram of Mg-Li binary alloy was observed. Preferential presence of Mg-Li-Sn primary precipitates (size 4-10 {mu}m) within {alpha}-Mg phase and Mg-Li-Al secondary precipitates (<3 {mu}m) interspersed in {beta}-Li indicated their degree of dissolution during hot-rolling and homogenization in the dual phase matrix. Presence of Al, Sn and Zn alloying elements in the Mg-Li based alloy has resulted an unusual dual-phase microstructure, change in the lattice parameter, and intriguing texture evolution after hot-rolling of cast LAT 971 and LATZ9531 alloy. Strong texture was absent in the as-cast samples whereas texture development after hot-rolling revealed an increased activity of the non-basal (101{sup Macron }0) slip planes. The quantification of the grain average misorientation (less than 2 Degree-Sign ) using electron backscattered diffraction confirmed the presence of strain free grains in majority of the grains (fraction >0.75) after hot-rolling of Mg

  3. Experimental and numerical simulation of thermomechanical phenomena during a TIG welding process

    International Nuclear Information System (INIS)

    Depradeux, L.; Julien, J.F.

    2004-01-01

    In this study, a parallel experimental and numerical simulation of phenomena that take place in the Heat Affected Zone (HAZ) during TIG welding on 316L stainless steel is presented. The aim of this study is to predict by numerical simulation residual stresses and distortions generated by the welding process. For the experiment, a very simple geometry with reduced dimensions is considered: the specimens are disks, made of 316L. The discs are heated in the central zone in order to reproduce thermo-mechanical cycles that take place in the HAZ during a TIG welding process. During and after thermal cycle, a large quantity of measurement is provided, and allows to compare the results of different numerical models used in the simulations. The comparative thermal and mechanical analysis allows to assess the general ability of the numerical models to describe the structural behavior. The importance of the heat input rate and material characteristics is also investigated. When a melted zone is created, the thermal simulation reproduce well the temperature field in the upper face of the disk, but the size of the weld pool is not correctly rated, as fluid flows are not taken into account. Despite this fact, the general structural behavior is well represented by simulation

  4. Effect of TMP variables upon structure and properties in ODS alloy HDA 8077 sheet. [ThermoMechanical Processing of Oxide Dispersion Strengthened nickel alloy

    Science.gov (United States)

    Rothman, M. F.; Tawancy, H. M.

    1980-01-01

    The effects of oxide content level and variations in thermomechanical processing upon the final structure and properties of HDA 8077 sheet have been systematically examined. It was found that creep strength and formability are substantially influenced by both oxide content and TMP schedule. Variations in creep properties obtained appear to correlate with observed microstructures.

  5. Theoretical approach to the WWER core thermomechanical modelling

    International Nuclear Information System (INIS)

    Likhatchev, Y.; Troyanov, V.; Folomeev, V.; Demishonkov, A.

    2003-01-01

    The paper presents studies on the analysis of root causes of fuel assembly bowing under operating conditions; developing of a methodology for fuel assemblies thermomechanical simulation; developing of a calculation technique for thermomechanical modelling of the fuel assemblies bowing in operational conditions. Some examples of calculation results are given

  6. Structure and Properties of Ti-19.7Nb-5.8Ta Shape Memory Alloy Subjected to Thermomechanical Processing Including Aging

    Science.gov (United States)

    Dubinskiy, S.; Brailovski, Vladimir; Prokoshkin, S.; Pushin, V.; Inaekyan, K.; Sheremetyev, V.; Petrzhik, M.; Filonov, M.

    2013-09-01

    In this work, the ternary Ti-19.7Nb-5.8Ta (at.%) alloy for biomedical applications was studied. The ingot was manufactured by vacuum arc melting with a consumable electrode and then subjected to hot forging. Specimens were cut from the ingot and processed by cold rolling with e = 0.37 of logarithmic thickness reduction and post-deformation annealing (PDA) between 400 and 750 °C (1 h). Selected samples were subjected to aging at 300 °C (10 min to 3 h). The influence of the thermomechanical processing on the alloy's structure, phase composition, and mechanical and functional properties was studied. It was shown that thermomechanical processing leads to the formation of a nanosubgrained structure (polygonized with subgrains below 100 nm) in the 500-600 °C PDA range, which transforms to a recrystallized structure of β-phase when PDA temperature increases. Simultaneously, the phase composition and the β → α″ transformation kinetics vary. It was found that after conventional cold rolling and PDA, Ti-Nb-Ta alloy manifests superelastic and shape memory behaviors. During aging at 300 °C (1 h), an important quantity of randomly scattered equiaxed ω-precipitates forms, which results in improved superelastic cyclic properties. On the other hand, aging at 300 °C (3 h) changes the ω-precipitates' particle morphology from equiaxed to elongated and leads to their coarsening, which negatively affects the superelastic and shape memory functional properties of Ti-Nb-Ta alloy.

  7. Self-positioning of polymer membranes driven by thermomechanically induced plastic deformation

    DEFF Research Database (Denmark)

    Häfliger, Daniel; Hansen, Ole; Boisen, Anja

    2006-01-01

    Stress in polymeric resins is tailored by a thermomechanical process. It allows for controlled self-positioning of membranes in microdevices (see Figure). The process makes specific use of plastic deformation that results from the low viscosity of the polymer. This demonstrates that polymers offer...... new approaches to microfabrication that cannot be realized for common semiconductor materials without severe difficulties....

  8. Petri neural network model for the effect of controlled thermomechanical process parameters on the mechanical properties of HSLA steels

    Energy Technology Data Exchange (ETDEWEB)

    Datta, S.

    1999-10-01

    The effect of composition and controlled thermomechanical process parameters on the mechanical properties of HSLA steels is modelled using the Widrow-Hoff's concept of training a neural net with feed-forward topology by applying Rumelhart's back propagation type algorithm for supervised learning, using a Petri like net structure. The data used are from laboratory experiments as well as from the published literature. The results from the neural network are found to be consistent and in good agreement with the experimented results. (author)

  9. Effect of Thermomechanical Processing on Microstructure, Texture Evolution, and Mechanical Properties of Al-Mg-Si-Cu Alloys with Different Zn Contents

    Science.gov (United States)

    Wang, X. F.; Guo, M. X.; Chen, Y.; Zhu, J.; Zhang, J. S.; Zhuang, L. Z.

    2017-07-01

    The effect of thermomechanical processing on microstructure, texture evolution, and mechanical properties of Al-Mg-Si-Cu alloys with different Zn contents was studied by mechanical properties, microstructure, and texture characterization in the present study. The results show that thermomechanical processing has a significant influence on the evolution of microstructure and texture and on the final mechanical properties, independently of Zn contents. Compared with the T4P-treated (first preaged at 353 K (80 °C) for 12 hours and then naturally aged for 14 days) sheets with high final cold rolling reduction, the T4P-treated sheets with low final cold rolling reduction possess almost identical strength and elongation and higher average r values. Compared with the intermediate annealed sheets with high final cold rolling reduction, the intermediate annealed sheets with low final cold rolling reduction contain a higher number of particles with a smaller size. After solution treatment, in contrast to the sheets with high final cold rolling reduction, the sheets with low final cold rolling reduction possess finer grain structure and tend to form a weaker recrystallization texture. The recrystallization texture may be affected by particle distribution, grain size, and final cold rolling texture. Finally, the visco-plastic self-consistent (VPSC) model was used to predict r values.

  10. Thermomechanical processing of Nb-1Zr-0.1C alloy for use in compact high temperature reactors: a first report

    International Nuclear Information System (INIS)

    Chakravartty, J.K.; Kapoor, R.; Suri, A.K.

    2011-08-01

    Nb-1Zr-0.1C is a potential material for use in high temperature nuclear reactors. Use of this alloy in components requires appropriate thermomechanical processing to break the cast microstructure and to obtain uniformly distributed fine stable precipitates so as to produce the desired mechanical properties at the high operating temperatures. This report reviews the thermomechanical processing of Nb-1Zr-0.1C alloy carried out over the years by other researchers and the high temperature creep behavior of the alloy. The hot deformation of Nb-1Zr-0.1C alloy carried out at Mechanical Metallurgy Division is also presented here. From this review it is evident that most primary hot working studies were carried out between 1500 to 1700 degC. The subsequent annealing treatments, which require holding at lower temperatures of about 1100 to 1300 degC for very long times help further transform the precipitates from coarse orthorhombic to very fine cubic. Our studies on Nb-1Zr-0.1C alloy also confirm that optimum hot working lies at temperatures beyond 1500 degC where dynamic recrystallization initiates, and optimally around 1700 degC where dynamic recrystallization transforms the microstructure. Working at temperatures lower than 1000 degC may lead to the undesirable effect of both micro as well as macro strain localization, and should be avoided. (author)

  11. Investigation on thermomechanical properties of poly (l-lactic acid) for the stretch blow moulding process of bioresorbable vascular scaffold

    Science.gov (United States)

    Wei, Huidong; Menary, Gary

    2017-10-01

    Stretch blow moulding process has been used for the manufacture of bioresorbable vascular scaffold (BVS) made by poly (l-lactic acid) (PLLA) to improve its mechanical performance. In order to better understand the process, thermomechanical properties of PLLA were investigated by experimental method. Extruded PLLA sheets were biaxial stretched under strain rate of 1s-1, 4s-1 and 16s-1 to simulate the deformation process applicable in the blow moulding process. Both the equal-biaxial stretch and constant-width stretch were conducted by an in-house developed equipment. By differential scanning calorimeter (DSC), thermal analysis for materials before and after stretch were compared to evaluate the microstructural change of PLLA materials in the deformation process. A constitutive model based on glass rubber model was presented to simulate the mechanical behaviour of PLLA above glass transition under biaxial deformation.

  12. PECULIARITIES OF FORMATION OF STRUCTURE AND PROPERTIES AT THERMO-MECHANICAL PROCESSING OF ROLLED WIRE OF NICKEL

    OpenAIRE

    V. A. Lutsenko

    2012-01-01

    There are results of researches of the mechanical properties and structure of the wire rod made of low-carbon nickel molybdenum steel after reduction to toughness thermomechanical treatment in the stream of high-speed wire mill.

  13. Precipitation behavior during thin slab thermomechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength structural steels: The effect on mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Misra, R.D.K., E-mail: dmisra@louisiana.edu [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Jia, Z. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); O' Malley, R. [Nucor Steel Decatur, LLC Sheet Mill, 4301, Iverson Blvd., Trinity, AL 35673 (United States); Jansto, S.J. [CBMM-Reference Metals Company, 1000 Old Pond Road, Bridgeville, PA 15017 (United States)

    2011-11-15

    Highlights: {yields} Copper does not significantly influence toughness. {yields} Copper precipitation during aging occurs at dislocations. {yields} Precipitation of copper and carbides is mutually exclusive. - Abstract: We describe here the precipitation behavior of copper and fine-scale carbides during thermo-mechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength steels. During thermo-mechanical processing, precipitation of {epsilon}-copper occurs in polygonal ferrite and at the austenite-ferrite interface. In contrast, during isothermal aging, nucleation of {epsilon}-copper precipitation occurs at dislocations. In the three different chemistries investigated, the increase in strength associated with copper during aging results only in a small decrease in impact toughness, implying that copper precipitates do not seriously impair toughness, and can be considered as a viable strengthening element in microalloyed steels. Precipitation of fine-scale niobium carbides occurs extensively at dislocations and within ferrite matrix together with vanadium carbides. In the presence of titanium, titanium carbides act as a nucleus for niobium carbide formation. Irrespective of the nature of carbides, copper precipitates and carbides are mutually exclusive.

  14. Precipitation behavior during thin slab thermomechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength structural steels: The effect on mechanical properties

    International Nuclear Information System (INIS)

    Misra, R.D.K.; Jia, Z.; O'Malley, R.; Jansto, S.J.

    2011-01-01

    Highlights: → Copper does not significantly influence toughness. → Copper precipitation during aging occurs at dislocations. → Precipitation of copper and carbides is mutually exclusive. - Abstract: We describe here the precipitation behavior of copper and fine-scale carbides during thermo-mechanical processing and isothermal aging of copper-bearing niobium-microalloyed high strength steels. During thermo-mechanical processing, precipitation of ε-copper occurs in polygonal ferrite and at the austenite-ferrite interface. In contrast, during isothermal aging, nucleation of ε-copper precipitation occurs at dislocations. In the three different chemistries investigated, the increase in strength associated with copper during aging results only in a small decrease in impact toughness, implying that copper precipitates do not seriously impair toughness, and can be considered as a viable strengthening element in microalloyed steels. Precipitation of fine-scale niobium carbides occurs extensively at dislocations and within ferrite matrix together with vanadium carbides. In the presence of titanium, titanium carbides act as a nucleus for niobium carbide formation. Irrespective of the nature of carbides, copper precipitates and carbides are mutually exclusive.

  15. Effect of Multipass TIG and Activated TIG Welding Process on the Thermo-Mechanical Behavior of 316LN Stainless Steel Weld Joints

    Science.gov (United States)

    Ganesh, K. C.; Balasubramanian, K. R.; Vasudevan, M.; Vasantharaja, P.; Chandrasekhar, N.

    2016-04-01

    The primary objective of this work was to develop a finite element model to predict the thermo-mechanical behavior of an activated tungsten inert gas (ATIG)-welded joint. The ATIG-welded joint was fabricated using 10 mm thickness of 316LN stainless steel plates in a single pass. To distinguish the merits of ATIG welding process, it was compared with manual multipass tungsten inert gas (MPTIG)-welded joint. The ATIG-welded joint was fabricated with square butt edge configuration using an activating flux developed in-house. The MPTIG-welded joint was fabricated in thirteen passes with V-groove edge configuration. The finite element model was developed to predict the transient temperature, residual stress, and distortion of the welded joints. Also, microhardness, impact toughness, tensile strength, ferrite measurement, and microstructure were characterized. Since most of the recent publications of ATIG-welded joint was focused on the molten weld pool dynamics, this research work gives an insight on the thermo-mechanical behavior of ATIG-welded joint over MPTIG-welded joint.

  16. Experimental study of thermo-mechanical behavior of a thermosetting shape-memory polymer

    Science.gov (United States)

    Liu, Ruoxuan; Li, Yunxin; Liu, Zishun

    2018-01-01

    The thermo-mechanical behavior of shape-memory polymers (SMPs) serves for the engineering applications of SMPs. Therefore the understanding of thermo-mechanical behavior of SMPs is of great importance. This paper investigates the influence of loading rate and loading level on the thermo-mechanical behavior of a thermosetting shape-memory polymer through experimental study. A series of cyclic tension tests and shape recovery tests at different loading conditions are performed to study the strain level and strain rate effect. The results of tension tests show that the thermosetting shape-memory polymer will behave as rubber material at temperature lower than the glass transition temperature (Tg) and it can obtain a large shape fix ratio at cyclic loading condition. The shape recovery tests exhibit that loading rate and loading level have little effect on the beginning and ending of shape recovery process of the thermosetting shape-memory polymer. Compared with the material which is deformed at temperature higher than Tg, the material deformed at temperature lower than Tg behaves a bigger recovery speed.

  17. COMPARATIVE ANALYSIS OF MECHANICAL CHARACTERISTICS OF THE STEELS, APPLIED FOR PRODUCTION OF CHIPPING KNIVES, RECEIVED BY METHODS OF THERMAL AND THERMOMECHANICAL PROCESSINGS

    Directory of Open Access Journals (Sweden)

    A. V. Alifanov

    2014-01-01

    Full Text Available Results of researches of chemical composition of chipping knives of foreign and domestic producers are given in the article. Results of mechanical tests of samples with determination of temporary resistance, percentage elongation, ultimate strength at cross bending, bend from the various tool steels, subjected to heat treatment (tempering and thermomechanical processing with low tempering, are given. Recommendations on use of TO and TMO for investigated steels are given.

  18. PECULIARITIES OF FORMATION OF STRUCTURE AND PROPERTIES AT THERMO-MECHANICAL PROCESSING OF ROLLED WIRE OF NICKEL

    Directory of Open Access Journals (Sweden)

    V. A. Lutsenko

    2012-01-01

    Full Text Available There are results of researches of the mechanical properties and structure of the wire rod made of low-carbon nickel molybdenum steel after reduction to toughness thermomechanical treatment in the stream of high-speed wire mill.

  19. Multi-step wrought processing of TiAl-based alloys

    International Nuclear Information System (INIS)

    Fuchs, G.E.

    1997-04-01

    Wrought processing will likely be needed for fabrication of a variety of TiAl-based alloy structural components. Laboratory and development work has usually relied on one-step forging to produce test material. Attempts to scale-up TiAl-based alloy processing has indicated that multi-step wrought processing is necessary. The purpose of this study was to examine potential multi-step processing routes, such as two-step isothermal forging and extrusion + isothermal forging. The effects of processing (I/M versus P/M), intermediate recrystallization heat treatments and processing route on the tensile and creep properties of Ti-48Al-2Nb-2Cr alloys were examined. The results of the testing were then compared to samples from the same heats of materials processed by one-step routes. Finally, by evaluating the effect of processing on microstructure and properties, optimized and potentially lower cost processing routes could be identified

  20. PWR fuel thermomechanics

    International Nuclear Information System (INIS)

    Traccucci, R.; Leclercq, J.

    1986-01-01

    Fuel thermo-mechanics means the studies of mechanical and thermal effects, and more generally, the studies of the behavior of the fuel assembly under stresses including thermal and mechanical loads, hydraulic effects and phenomena induced by materials irradiation. This paper describes the studies dealing with the fuel assembly behavior, first in normal operating conditions, and then in accidental conditions. 43 refs [fr

  1. A 1D thermomechanical network transition constitutive model coupled with multiple structural relaxation for shape memory polymers

    Science.gov (United States)

    Zeng, Hao; Xie, Zhimin; Gu, Jianping; Sun, Huiyu

    2018-03-01

    A new thermomechanical network transition constitutive model is proposed in the study to describe the viscoelastic behavior of shape memory polymers (SMPs). Based on the microstructure of semi-crystalline SMPs, a new simplified transformation equation is proposed to describe the transform of transient networks. And the generalized fractional Maxwell model is introduced in the paper to estimate the temperature-dependent storage modulus. In addition, a neo-KAHR theory with multiple discrete relaxation processes is put forward to study the structural relaxation of the nonlinear thermal strain in cooling/heating processes. The evolution equations of the time- and temperature-dependent stress and strain response are developed. In the model, the thermodynamical and mechanical characteristics of SMPs in the typical thermomechanical cycle are described clearly and the irreversible deformation is studied in detail. Finally, the typical thermomechanical cycles are simulated using the present constitutive model, and the simulation results agree well with the experimental results.

  2. The effect of thermo-mechanical processing on the mechanical properties of molybdenum - 2 volume % lanthana

    International Nuclear Information System (INIS)

    Mueller, A.J.; Shields, J.A. Jr.; Buckman, R.W. Jr.

    2001-01-01

    Variations in oxide species and consolidation method have been shown to have a significant effect on the mechanical properties of oxide dispersion strengthened (ODS) molybdenum material. The mechanical behavior of molybdenum - 2 volume % La 2 O 3 mill product forms, produced by CSM Industries by a wet doping process, were characterized over the temperature range of -150 o C to 1800 o C. The various mill product forms evaluated ranged from thin sheet stock to bar stock. Tensile properties of the material in the various product forms were not significantly affected by the vast difference in total cold work. Creep properties, however, were sensitive to the total amount of cold work as well as the starting microstructure. Stress-relieved .material had superior creep rupture properties to recrystallized material at 1200 o C, while at 1500 o C and above the opposite was observed. Thus it is necessary to match the appropriate thermo-mechanical processing and microstructure of molybdenum - 2 volume % La 2 O 3 to the demands of the application being considered. (author)

  3. Thermo-mechanical constitutive modeling of unsaturated clays based on the critical state concepts

    Directory of Open Access Journals (Sweden)

    Saeed Tourchi

    2015-04-01

    Full Text Available A thermo-mechanical constitutive model for unsaturated clays is constructed based on the existing model for saturated clays originally proposed by the authors. The saturated clays model was formulated in the framework of critical state soil mechanics and modified Cam-clay model. The existing model has been generalized to simulate the experimentally observed behavior of unsaturated clays by introducing Bishop's stress and suction as independent stress parameters and modifying the hardening rule and yield criterion to take into account the role of suction. Also, according to previous studies, an increase in temperature causes a reduction in specific volume. A reduction in suction (wetting for a given confining stress may induce an irreversible volumetric compression (collapse. Thus an increase in suction (drying raises a specific volume i.e. the movement of normal consolidation line (NCL to higher values of void ratio. However, some experimental data confirm the assumption that this reduction is dependent on the stress level of soil element. A generalized approach considering the effect of stress level on the magnitude of clays thermal dependency in compression plane is proposed in this study. The number of modeling parameters is kept to a minimum, and they all have clear physical interpretations, to facilitate the usefulness of model for practical applications. A step-by-step procedure used for parameter calibration is also described. The model is finally evaluated using a comprehensive set of experimental data for the thermo-mechanical behavior of unsaturated soils.

  4. The effects of thermomechanical history on the microstructure of a nickel-base superalloy during forging

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, S., E-mail: 485354@swansea.ac.uk [College of Engineering, Bay Campus, Swansea University, Swansea SA1 8EN (United Kingdom); Li, W. [Rolls-Royce plc, PO Box 31, Derby DE24 8BJ (United Kingdom); Coleman, M. [College of Engineering, Bay Campus, Swansea University, Swansea SA1 8EN (United Kingdom); Johnston, R., E-mail: r.johnston@swansea.ac.uk [College of Engineering, Bay Campus, Swansea University, Swansea SA1 8EN (United Kingdom)

    2016-06-21

    The effect of thermo-mechanical history on hot compression behaviour and resulting microstructures of a nickel base superalloy is presented. Hot compression tests were carried out on HAYNES® 282® specimens to varying strains from 0.1 to 0.8. Both single pass and multi-pass tests were completed. 60 min inter-pass times were utilized to accurately replicate industrial forging practices. The effect of dynamic, metadynamic and static recrystallization during inter-pass times on flow stress was investigated. The resulting microstructures were analysed using scanning electron, optical microscopy and EBSD to relate grain size and homogeneity with flow stress data. The study showed a negligible difference between multi-pass and single pass tests for strain increments above 0.2. Therefore, when modelling similar low strain and strain rate forging processes in HAYNES® 282®, previous forging steps can be ignored.

  5. Ten steps to successful software process improvement

    Science.gov (United States)

    Kandt, R. K.

    2003-01-01

    This paper identifies ten steps for managing change that address organizational and cultural issues. Four of these steps are critical, that if not done, will almost guarantee failure. This ten-step program emphasizes the alignment of business goals, change process goals, and the work performed by the employees of an organization.

  6. The Mg{sub 2}Si phase evolution during thermomechanical processing of in-situ aluminum matrix macro-composite

    Energy Technology Data Exchange (ETDEWEB)

    Shafieizad, A.H. [The Complex Laboratory of Hot Deformation & Thermomechanical Processing of High Performance Engineering Materials, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Zarei-Hanzaki, A., E-mail: Zareih@ut.ac.ir [The Complex Laboratory of Hot Deformation & Thermomechanical Processing of High Performance Engineering Materials, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Abedi, H.R. [The Complex Laboratory of Hot Deformation & Thermomechanical Processing of High Performance Engineering Materials, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Al-Fadhalah, K.J. [Department of Mechanical Engineering, College of Engineering & Petroleum, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait)

    2015-09-17

    The microstructure and flow stress behavior of thermomechanically processed Al–Cu/Mg{sub 2}Si in-situ composite was studied emphasizing the evolution of primary and secondary reinforcement phases. Toward this end, the hot compression tests were conducted over the wide range of temperature (300–500 °C) and strain rate (0.001–0.1 s{sup −1}). Both the temperature and strain rate are found to possess a significant effect on the microstructural characteristics where a considerable softening is identified specially at low temperature regime. Besides the occurrence of restoration processes (mainly particle stimulated nucleation) the dynamic evolution of the reinforcements is introduced as the main factors affecting the reported softening. In this regard, the mechanical fragmentation, thermal disintegration, micro-buckling, coalescence and spheroidization of the primary and secondary particles are quantitatively and qualitatively addressed through a comprehensive scanning electron microscopy studies.

  7. Adjoint sensitivity analysis of the thermomechanical behavior of repositories

    International Nuclear Information System (INIS)

    Wilson, J.L.; Thompson, B.M.

    1984-01-01

    The adjoint sensitivity method is applied to thermomechanical models for the first time. The method provides an efficient and inexpensive answer to the question: how sensitive are thermomechanical predictions to assumed parameters. The answer is exact, in the sense that it yields exact derivatives of response measures to parameters, and approximate, in the sense that projections of the response fo other parameter assumptions are only first order correct. The method is applied to linear finite element models of thermomechanical behavior. Extensions to more complicated models are straight-forward but often laborious. An illustration of the method with a two-dimensional repository corridor model reveals that the chosen stress response measure was most sensitive to Poisson's ratio for the rock matrix

  8. Multivariate statistical analysis of a multi-step industrial processes

    DEFF Research Database (Denmark)

    Reinikainen, S.P.; Høskuldsson, Agnar

    2007-01-01

    Monitoring and quality control of industrial processes often produce information on how the data have been obtained. In batch processes, for instance, the process is carried out in stages; some process or control parameters are set at each stage. However, the obtained data might not be utilized...... efficiently, even if this information may reveal significant knowledge about process dynamics or ongoing phenomena. When studying the process data, it may be important to analyse the data in the light of the physical or time-wise development of each process step. In this paper, a unified approach to analyse...... multivariate multi-step processes, where results from each step are used to evaluate future results, is presented. The methods presented are based on Priority PLS Regression. The basic idea is to compute the weights in the regression analysis for given steps, but adjust all data by the resulting score vectors...

  9. Finite elements for the thermomechanical calculation of massive structures

    International Nuclear Information System (INIS)

    Argyris, J.H.; Szimmat, J.; Willam, K.J.

    1978-01-01

    The paper examines the fine element analysis of thermal stress and deformation problems in massive structures. To this end compatible idealizations are utilized for heat conduction and static analysis in order to minimize the data transfer. For transient behaviour due to unsteady heat flow and/or inelastics material processes the two computational parts are interwoven in form of an integrated software package for finite element analysis of thermomechanical problems in space and time. (orig.) [de

  10. Magnetostriction Increase of Polycrystalline Fe-Al-B Thin Sheets after Thermomechanical Process

    Science.gov (United States)

    Dias, M. B. S.; Fulop, G. O.; Baldan, C. A.; Bormio-Nunes, C.

    2017-12-01

    Magnetostrictive materials are applied in several types of sensors, actuators, and energy harvesting. In particular, for AC devices, thin materials are desired to reduce eddy current losses. It is well known that the magnetostriction of single crystals and textured materials is higher than in polycrystalline ones, however, the cost and manufacture speed are crucial to be used as parts of commercial devices. Therefore, polycrystalline samples are strong candidates for common applications. In this work, (Fe x Al100- x )98.4B1.6 ( x = 86.6, 82 and 79.4) alloys were rolled down to 0.7 mm of thickness and annealed at 1473 K (1200 °C) for 2 hours aiming to reduce the thickness of the samples without deteriorating the magnetic properties. The alloys, even with higher contents of Al, were easily deformed to the thickness of 0.7 mm and this ability is attributed to the presence of the Fe2B phase. After the thermomechanical process, new isotropic recrystallized grains emerged and the longitudinal magnetostriction increased to 75.8, 16.9, and 3.2 pct, achieving 28.3, 28.4, and 28.8 ppm, respectively, for x = 86.6, 82, and 79.4. The piezomagnetic coefficient obtained of 4 nm/A is a suitable actuating sensitivity.

  11. A Thermomechanical Transport Approach and Application in Soil-Water System of Polluted Mining Areas considering the Three-Phase Coupling

    Directory of Open Access Journals (Sweden)

    Xuan Guo

    2016-01-01

    Full Text Available The thermomechanical transport approach includes the process of diffusing or the condition of being diffused, absorption/desorption, swell/shrink, equilibrium/nonequilibrium, and thermomechanical transport of contaminant in three phases of polluted mining soil which are discussed. The thermomechanical transport model of the contaminants transport in polluted soil is established, and its basic equations are given. Based on that, the distribution regularities of the contaminant seepage in water-soil system are discussed in detail and the sensitivities of parameters are analyzed. The study shows that the parameter has important influence on the contamination distribution and transportation in polluted soil-water system. The influence degree is also related to the action of seepage force directly.

  12. Residual Stresses in DC cast Aluminum Billet: Neutron Diffraction Measurements and Thermomechanical Modeling

    International Nuclear Information System (INIS)

    Drezet, J.-M.; Evans, A.; Pirling, T.

    2011-01-01

    Thermally-induced residual stresses, generated during the industrial Direct Chill casting process of aluminum alloys, can cause both significant safety concerns as well as the formation of defects during down-stream processing. Although these thermally induced strains can be partially relieved by permanent deformation, cracks will be generated either during solidification (hot tears) or post-solidification cooling (cold cracks) when stresses exceed the deformation limit of the alloy. Furthermore, the thermally induced strains result in the presence of large internal stresses within the billet before further processing steps. Although numerical models have been previously developed to compute these residual stresses, most of the computations have been validated only against measured surface distortions. In the present work, the variation in residual elastic strains and stresses in the steady state regime of casting has been measured as a function of radial position using neutron diffraction in an AA6063 grain-refined cylindrical billet. These measurements have been carried out on the same billet section at Poldi at PSI-Villigen and at Salsa at ILL-Grenoble and compare favorably. The results are used to validate a thermo-mechanical finite element casting model and to assess the level of stored elastic energy within the billet.

  13. Development of microstructure in thermomechanical processing of zirconium alloys

    International Nuclear Information System (INIS)

    Jha, S.K.; Saibaba, N.; Jayaraj, R.N.

    2009-01-01

    Zirconium based alloys are used for the manufacture of fuel tubes pressure tubes calandria tubes and other components of Pressurized Heavy Water Reactors (PHWRS). In single or two phase zirconium alloy system a variety of microstructure can be generated by suitable heat treatments by the process of equilibrium and non equilibrium phase transformations Microstructure can also be modified by alloying with α and β stabilizers. The microstructure in Zr alloys could be single hexagonal phase (α alloys) two phase bcc and hexagonal (α + β alloys) phase, single metastable martensitic microstructure and β with ω phase. The microstructural and micro textural evolution during thermo mechanical treatments depends strongly on such initial microstructure. Hot extrusion is a significant bulk deformation step which decides the initial microstructure of the alloy. It is carried out at elevated temperature i e above the recrystallization temperature, which enable imposition of large strains in single step. This deformation causes a significant change in the microstructure of the material and depends on extrusion process parameters such as temperature, strain rate (Ram speed), reduction ratio etc. In the present paper development of microstructures, microtexture and texture have been examined. An attempt is also made to optimise the hot working parameters for different Zirconium alloys with help of these studies. (author)

  14. Thermo-mechanical properties of SOFC components investigated by a combined method

    DEFF Research Database (Denmark)

    Teocoli, Francesca; Esposito, Vincenzo; Ramousse, Severine

    , and differential thermo-mechanical behavior at each layer. The combination of such factors can have a critical effect on the final shape and microstructure, and on the mechanical integrity. Thermo-mechanical properties and sintering mechanisms of important SOFC materials (CGO, YSZ, ScYSZ) were systematically...

  15. Data-based control of a multi-step forming process

    Science.gov (United States)

    Schulte, R.; Frey, P.; Hildenbrand, P.; Vogel, M.; Betz, C.; Lechner, M.; Merklein, M.

    2017-09-01

    The fourth industrial revolution represents a new stage in the organization and management of the entire value chain. However, concerning the field of forming technology, the fourth industrial revolution has only arrived gradually until now. In order to make a valuable contribution to the digital factory the controlling of a multistage forming process was investigated. Within the framework of the investigation, an abstracted and transferable model is used to outline which data have to be collected, how an interface between the different forming machines can be designed tangible and which control tasks must be fulfilled. The goal of this investigation was to control the subsequent process step based on the data recorded in the first step. The investigated process chain links various metal forming processes, which are typical elements of a multi-step forming process. Data recorded in the first step of the process chain is analyzed and processed for an improved process control of the subsequent process. On the basis of the gained scientific knowledge, it is possible to make forming operations more robust and at the same time more flexible, and thus create the fundament for linking various production processes in an efficient way.

  16. Effect of Thermomechanical Processing and Crystallographic Orientation on the Corrosion Behavior of API 5L X70 Pipeline Steel

    Science.gov (United States)

    Ohaeri, Enyinnaya; Omale, Joseph; Eduok, Ubong; Szpunar, Jerzy

    2018-04-01

    This work presents the electrochemical response of X70 pipeline steel substrates thermomechanically processed at different conditions. The WE sample was hot rolled at a temperature range of 850 °C to 805 °C and cooled at a rate of 42.75 °C/s. Another sample WD was hot rolled from 880 °C to 815 °C and cooled at a faster rate of 51.5 °C/s. Corrosion tests were conducted electrochemically by potentiodynamic polarization in hydrogen-charged and non-hydrogen-charged environments. A lower corrosion rate was measured with hydrogen charging due to the rapid formation of corrosion product film on pipeline substrate, but WE specimen emerged as the most susceptible to corrosion with and without hydrogen charging. Variations in thermomechanical rolling conditions influenced grain orientation, protective film properties, corrosion, and cracking behavior on both specimens. Cracks were seen in both specimens after hydrogen charging, but specimen WE experienced a more intense deterioration of protective corrosion product film and subsequent cracking. A large part of specimen WD retained its protective corrosion product film after the polarization test, and sites where spalling occurred resulted in pitting with less cracking. Despite weak crystallographic texture noticed in both specimens, WD showed a higher intensity of corrosion-resistant 111||ND-oriented grains, while WE showed a more random distribution of 111||ND-, 011||ND-, and 001||ND-oriented grains with a lower intensity.

  17. Effect of Thermomechanical Processing and Crystallographic Orientation on the Corrosion Behavior of API 5L X70 Pipeline Steel

    Science.gov (United States)

    Ohaeri, Enyinnaya; Omale, Joseph; Eduok, Ubong; Szpunar, Jerzy

    2018-06-01

    This work presents the electrochemical response of X70 pipeline steel substrates thermomechanically processed at different conditions. The WE sample was hot rolled at a temperature range of 850 °C to 805 °C and cooled at a rate of 42.75 °C/s. Another sample WD was hot rolled from 880 °C to 815 °C and cooled at a faster rate of 51.5 °C/s. Corrosion tests were conducted electrochemically by potentiodynamic polarization in hydrogen-charged and non-hydrogen-charged environments. A lower corrosion rate was measured with hydrogen charging due to the rapid formation of corrosion product film on pipeline substrate, but WE specimen emerged as the most susceptible to corrosion with and without hydrogen charging. Variations in thermomechanical rolling conditions influenced grain orientation, protective film properties, corrosion, and cracking behavior on both specimens. Cracks were seen in both specimens after hydrogen charging, but specimen WE experienced a more intense deterioration of protective corrosion product film and subsequent cracking. A large part of specimen WD retained its protective corrosion product film after the polarization test, and sites where spalling occurred resulted in pitting with less cracking. Despite weak crystallographic texture noticed in both specimens, WD showed a higher intensity of corrosion-resistant 111|| ND-oriented grains, while WE showed a more random distribution of 111|| ND-, 011|| ND-, and 001|| ND-oriented grains with a lower intensity.

  18. The influence of thermo-mechanical processing on the microstructure of steel 20MoCrS4

    Energy Technology Data Exchange (ETDEWEB)

    Jandova, D.; Meyer, L.W.; Masek, B.; Novy, Z.; Kesner, D.; Motycka, P

    2003-05-25

    The influence of thermo-mechanical processing (TMP) on the microstructure and mechanical properties of 0.22%C-0.87%Mn-0.73Cr-0.40Mo steel was investigated. The transformation CCT diagram and CCCT diagram were determined by dilatometric measurements. Hot deformation before austenite decomposition slightly accelerates ferritic transformation, retards bainitic reactions and decreases the bainite start temperature. Special methods of TMP were performed consisting of hot and/or warm compression deformations and dwell at an elevated temperature. The microstructure was studied using metallography and transmission electron microscopy. The compression deformation results in a remarkable refinement of the microstructure and an improvement of mechanical properties. Warm deformation followed by dwell at 470 deg. C was found to be suitable for an increase of tensile strength and notch toughness; the corresponding microstructure is a fine lath-like bainitic microstructure with a relatively homogeneous distribution of carbide particles.

  19. Introduction to nonlinear thermomechanics of solids

    CERN Document Server

    Kleiber, Michał

    2016-01-01

    The first part of this textbook presents the mathematical background needed to precisely describe the basic problem of continuum thermomechanics. The book then concentrates on developing governing equations for the problem dealing in turn with the kinematics of material continuum, description of the state of stress, discussion of the fundamental conservation laws of underlying physics, formulation of initial-boundary value problems and presenting weak (variational) formulations. In the final part the crucial issue of developing techniques for solving specific problems of thermomechanics is addressed. To this aim the authors present a discretized formulation of the governing equations, discuss the fundamentals of the finite element method and develop some basic algorithms for solving algebraic and ordinary differential equations typical of problems on hand. Theoretical derivations are followed by carefully prepared computational exercises and solutions.

  20. Thermo-mechanical modeling of laser treatment on titanium cold-spray coatings

    Science.gov (United States)

    Paradiso, V.; Rubino, F.; Tucci, F.; Astarita, A.; Carlone, P.

    2018-05-01

    Titanium coatings are very attractive to several industrial fields, especially aeronautics, due to the enhanced corrosion resistance and wear properties as well as improved compatibility with carbon fiber reinforced plastic (CFRP) materials. Cold sprayed titanium coatings, among the others deposition processes, are finding a widespread use in high performance applications, whereas post-deposition treatments are often used to modify the microstructure of the cold-sprayed layer. Laser treatments allow one to noticeably increase the superficial properties of titanium coatings when the process parameters are properly set. On the other hand, the high heat input required to melt titanium particles may result in excessive temperature increase even in the substrate. This paper introduces a thermo-mechanical model to simulate the laser treatment effects on a cold sprayed titanium coating as well as the aluminium substrate. The proposed thermo-mechanical finite element model considers the transient temperature field due to the laser source and applied boundary conditions using them as input loads for the subsequent stress-strain analysis. Numerical outcomes highlighted the relevance of thermal gradients and thermally induced stresses and strains in promoting the damage of the coating.

  1. Modelling the Thermo-Mechanical Behavior of Magnesium Alloys during Indirect Extrusion

    International Nuclear Information System (INIS)

    Steglich, D.; Ertuerk, S.; Bohlen, J.; Letzig, D.; Brocks, W.

    2010-01-01

    One of the basic metal forming process for semi-finished products is extrusion. Since extrusion involves complex thermo-mechanical and multiaxial loading conditions resulting in large strains, high strain rates and an increase in temperature due to deformation, a proper yield criterion and hardening law should be used in the numerical modelling of the process. A phenomenological model based on a plastic potential has been proposed that takes strain, strain rate and temperature dependency on flow behaviour into consideration. A hybrid methodology of experiment and finite element simulation has been adopted in order to obtain necessary model parameters. The anisotropy/asymmetry in yielding was quantified by tensile and compression tests of specimens prepared from different directions. The identification of the corresponding model parameters was performed by a genetic algorithm. A fully coupled thermo-mechanical analysis has been used in extrusion simulations for calculation of the temperature field by considering heat fluxes and heat generated due to plastic deformation. The results of the approach adopted in this study appeared to be successful showing promising predictions of the experiments and thus may be extended to be applicable to other magnesium alloys or even other hcp metals.

  2. A thermomechanical crystal plasticity constitutive model for ultrasonic consolidation

    KAUST Repository

    Siddiq, Amir

    2012-01-01

    We present a micromechanics-based thermomechanical constitutive model to simulate the ultrasonic consolidation process. Model parameters are calibrated using an inverse modeling approach. A comparison of the simulated response and experimental results for uniaxial tests validate and verify the appropriateness of the proposed model. Moreover, simulation results of polycrystalline aluminum using the identified crystal plasticity based material parameters are compared qualitatively with the electron back scattering diffraction (EBSD) results reported in the literature. The validated constitutive model is then used to simulate the ultrasonic consolidation process at sub-micron scale where an effort is exerted to quantify the underlying micromechanisms involved during the ultrasonic consolidation process. © 2011 Elsevier B.V. All rights reserved.

  3. Two-Step Plasma Process for Cleaning Indium Bonding Bumps

    Science.gov (United States)

    Greer, Harold F.; Vasquez, Richard P.; Jones, Todd J.; Hoenk, Michael E.; Dickie, Matthew R.; Nikzad, Shouleh

    2009-01-01

    A two-step plasma process has been developed as a means of removing surface oxide layers from indium bumps used in flip-chip hybridization (bump bonding) of integrated circuits. The two-step plasma process makes it possible to remove surface indium oxide, without incurring the adverse effects of the acid etching process.

  4. Effect of oxygen on the thermomechanical behavior of tantalum thin films during the β-α phase transformation

    International Nuclear Information System (INIS)

    Knepper, Robert; Stevens, Blake; Baker, Shefford P.

    2006-01-01

    Tantalum thin films were prepared in the metastable β phase, and their thermomechanical behaviors were investigated in situ in an ultrahigh vacuum environment. Controlled levels of oxygen were incorporated into the films either during deposition, by surface oxidation after deposition, or during thermomechanical testing. The transformation from the β phase to the stable α phase takes place in conjunction with a distinct increase in tensile stress. The thermomechanical behavior is strongly affected by the amount of oxygen to which the film is exposed and the method of exposure. Increasing oxygen content inhibits the phase transformation, requiring higher temperatures to reach completion. It is shown that the phase transformation takes place by a nucleation and growth process that is limited by growth. Changes in the activation energy for the phase transformation due to solute drag are estimated as a function of oxygen content and the mechanisms behind the stress evolution are elucidated

  5. Computerized simulation of YAG pulse laser welding of titanium alloy (TA6V): experimental characterization and modelling of the thermomechanical aspects of this process

    International Nuclear Information System (INIS)

    Robert, Y.

    2007-09-01

    This work is a part of study which goal is to realize a computer modelling of the thermomechanical phenomena occurring during the YAG pulse laser welding of titanium alloy (TA6V). The filet welding has different heterogeneities (microstructural and mechanical). In fact, the temperature causes microstructural changes (phase transformations, precipitations) and modifies the mechanical properties. Thermomechanical modelling has thus to be established for the welding of TA6V. (author)

  6. Development process and data management of TurnSTEP, a STEP-compliant CNC system for turning

    NARCIS (Netherlands)

    Choi, I.; Suh, S.-H; Kim, K.; Song, M.S.; Jang, M.; Lee, B.-E.

    2006-01-01

    TurnSTEP is one of the earliest STEP-compliant CNC systems for turning. Based on the STEP-NC data model formalized as ISO 14649-12 and 121, it is designed to support intelligent and autonomous control of NC machines for e-manufacturing. The present paper introduces the development process and data

  7. Efficient thermo-mechanical generation of electricity from the heat of radioisotopes

    International Nuclear Information System (INIS)

    Cooke-Yarborough, E.H.; Yeats, F.W.

    1975-01-01

    The thermomechanical generator uses a thermomechanical oscillator to convert heat efficiently into a mechanical oscillation which in turn excites a suitable transducer to generate alternating electricity. The thermomechanical oscillator used is based on the Stirling cycle, but avoids the need for rotary motion and for sliding pistons by having a mechanically-resonant, spring-suspended displacer, and by using an oscillating metal diaphragm to provide the mechanical output. The diaphragm drives an alternator consisting of a spring-suspended permanent magnet oscillating between fixed pole pieces which carry the electrical power output windings. Because a thermomechanical generator is much more efficient than a thermo-electric generator at comparable temperatures, it is particularly suitable for use with a radioisotope heat source. The amounts of radioisotope and of shielding required are both greatly reduced. A machine heated by radioisotopes and delivering 10.7W ac at 80Hz began operating in October, 1974. Operating experience with this machine is reported, and these results, together with those obtained with higher-powered machines heated by other means, are used to calculate characteristics and performance of thermo-mechanical radioisotope generators capable of using heat sources such as the waste-management 90 Sr radioisotope sources becoming available from the US nuclear waste management programme. A design to use one of these heat sources in a 52-W underwater generator is described

  8. Thermo-mechanical response and fatigue behavior of shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kusagawa, Masaki; Asada, Yasuhide; Nakamura, Toshiya [Tokyo Univ. (Japan). Dept. of Mechanical Engineering

    1998-11-01

    Mechanical, thermo-mechanical and fatigue behaviors of Ni-Ti-Nb shape memory alloy (SMA) have been studied to prepare material data for a design purpose. Presented are testing devices, testing procedure and test results of monotonic tensile, recovery of inelastic deformation due to post heating (thermo-mechanical recovery) and fatigue for future use of the SMA as a structural material of nuclear incore structures. (orig.)

  9. Thermo-mechanical response and fatigue behavior of shape memory alloy

    International Nuclear Information System (INIS)

    Kusagawa, Masaki; Asada, Yasuhide; Nakamura, Toshiya

    1998-01-01

    Mechanical, thermo-mechanical and fatigue behaviors of Ni-Ti-Nb shape memory alloy (SMA) have been studied to prepare material data for a design purpose. Presented are testing devices, testing procedure and test results of monotonic tensile, recovery of inelastic deformation due to post heating (thermo-mechanical recovery) and fatigue for future use of the SMA as a structural material of nuclear incore structures. (orig.)

  10. Thermomechanical processing of aluminum micro-alloyed with Sc, Zr, Ti, B, and C

    Science.gov (United States)

    McNamara, Cameron T.

    Critical exploration of the minimalistic high strength low alloy aluminum (HSLA-Al) paradigm is necessary for the continued development of advanced aluminum alloys. In this study, scandium (Sc) and zirconium (Zr) are examined as the main precipitation strengthening additions, while magnesium (Mg) is added to probe the synergistic effects of solution and precipitation hardening, as well as the grain refinement during solidification afforded by a moderate growth restriction factor. Further, pathways of recrystallization are explored in several potential HSLA-Al syste =ms sans Sc. Aluminum-titanium-boron (Al-Ti-B) and aluminum-titanium-carbon (Al-Ti-C) grain refining master alloys are added to a series of Al-Zr alloys to examine both the reported Zr poisoning effect on grain size reduction and the impact on recrystallization resistance through the use of electron backscattered diffraction (EBSD) imaging. Results include an analysis of active strengthening mechanisms and advisement for both constitution and thermomechanical processing of HSLA-Al alloys for wrought or near-net shape cast components. The mechanisms of recrystallization are discussed for alloys which contain a bimodal distribution of particles, some of which act as nucleation sites for grain formation during annealing and others which restrict the growth of the newly formed grains.

  11. Thermomechanical cycling and two-way memory effect induced in Cu-Zn-Al

    International Nuclear Information System (INIS)

    Pons, J.

    1999-01-01

    The two-way shape memory effect (TWME) has been induced by thermomechanical cycling in Cu-Zn-Al alloys using a dedicated hydraulic mechanical testing soft machine with complete computer control of force, elongation and temperature. The results concerning single crystals (composition Cu-16.9 wt.% Zn-7.7 wt.% Al, nominal M s of 273 K) and polycrystals (Cu-15.8 wt.% Zn-8.3 wt.% Al, nominal M s of 230 K, mean grain size of 1 mm) are reported for two training protocols (sequence of one thermomechanical cycle of education followed by one stress free thermal cycle to check the TWME or twenty consecutive thermomechanical cycles followed by one or two checking thermal cycles). The capacity of the trained specimen for producing work under an antagonist compressive stress is also studied and the behaviour of the deformation of the specimen under such a condition at different temperatures is analysed in terms of a competition between the contributions of the different variants: trained variants with an intrinsic deformation in the direction of the tensile stress of the training process, trained variants with an intrinsic deformation which is not well orientated with respect to this direction (in the polycrystal) and new variants with an intrinsic deformation in the direction of the compressive stress which can replace the educated variants. (orig.)

  12. Mechanical Characterization of Thermomechanical Matrix Residual Stresses Incurred During MMC Processing

    Science.gov (United States)

    Castelli, Michael G.

    1998-01-01

    In recent years, much effort has been spent examining the residual stress-strain states of advanced composites. Such examinations are motivated by a number of significant concerns that affect composite development, processing, and analysis. The room-temperature residual stress states incurred in many advanced composite systems are often quite large and can introduce damage even prior to the first external mechanical loading of the material. These stresses, which are induced during the cooldown following high-temperature consolidation, result from the coefficient of thermal expansion mismatch between the fiber and matrix. Experimental techniques commonly used to evaluate composite internal residual stress states are non-mechanical in nature and generally include forms of x-ray and neutron diffraction. Such approaches are usually complex, involving a number of assumptions and limitations associated with a wide range of issues, including the depth of penetration, the volume of material being assessed, and erroneous effects associated with oriented grains. Furthermore, and more important to the present research, these techniques can assess only "single time" stress in the composite. That is, little, if any, information is obtained that addresses the time-dependent point at which internal stresses begin to accumulate, the manner in which the accumulation occurs, and the presiding relationships between thermoelastic, thermoplastic, and thermoviscous behaviors. To address these critical issues, researchers at the NASA Lewis Research Center developed and implemented an innovative mechanical test technique to examine in real time, the time-dependent thermomechanical stress behavior of a matrix alloy as it went through a consolidation cycle.

  13. Effect of low-temperature thermomechanical treatment on mechanical properties of low-alloying molybdenum alloys with carbide hardening

    International Nuclear Information System (INIS)

    Bernshtejn, L.M.; Zakharov, A.M.; Veller, M.V.

    1978-01-01

    Presented are results of testing low-temperature thermomechanical treatment of low-alloying molybdenum alloys, including quenching from 2100 deg C, 40% deformation by hydroextrusion and aging at the temperature of 1200-1400 deg C. Tensile tests at room temperature with the following processing of results have shown that low-temperature thermomechanical treatment of low-alloying molybdenum alloys of Mo-Zr-C and Mo-Zr-Nb-C systems leads to a significant increase in low-temperature mechanical properties (strength properties - by 30-35%, ductility - by 30-40%) as compared with conventional heat treatment (aging after quenching). The treatment proposed increases resistance to small, as well as large plastic deformations, and leads to a simultaneous rise of strength and plastic properties at all stages of tensile test. Alloying of the Mo-Zr-C system with niobium increases both strength and plastic characteristics as compared with alloys without niobium when testing samples, subjected to low temperature thermomechanical treatment and conventional heat treatment at room temperature

  14. Influence of thermomechanical treatment on microstructure and properties of electroslag remelted Cu–Cr–Zr alloy

    International Nuclear Information System (INIS)

    Kermajani, M.; Raygan, Sh.; Hanayi, K.; Ghaffari, H.

    2013-01-01

    Highlights: • Effect of ESR process on microstructure of Cu–Cr–Zr alloy was investigated. • The hardness, strength and electrical conductivity are sensitive to thermomechanical treatment. • The microstructure of the alloy can be optimized for obtaining the best combination of mechanical and electrical properties. - Abstract: Effect of thermomechanical treatment (TMT) on aging behavior of electroslag remelted Cu–Cr–Zr alloy was investigated. The relationship between microstructure, mechanical and electrical properties was clarified using hardness, tensile and electrical conductivity testing methods and optical and scanning electron microscopy techniques. The results showed that an appropriate processing and aging treatment may improve the properties of the alloy due to the formation of fine, dispersive and coherent precipitates within the matrix. Indeed, the optimum condition for electrical conductivity and mechanical properties was obtained after cold working of 40% followed by aging at 500 °C for 150 min

  15. Thermomechanical behavior of an Fe-based shape memory alloy: transformation conditions and hystereses

    International Nuclear Information System (INIS)

    Tanaka, K.; Nishimura, F.; Tobushi, H.; Oberaigner, E.R.; Fischer, F.D.

    1995-01-01

    Transformation/thermomechanical behavior in an Fe-9%Cr-5%Ni-14%Mn-6%Si polycrystalline shape memory alloy during thermomechanical loading is investigated. The transformation lines in the stress-temperature plane are strongly influenced by the parameters characterizing the thermomechanical loading. The transformation start condition, the martensite start stress and the austenite start temperature, is carefully measured to compare the results with the other experimental and theoretical observations. The stress-strain-temperature hysteresis loops, full and sub, are determined during cyclic loading. (orig.)

  16. Advance development of a technique for characterizing the thermomechanical properties of thermally stable polymers

    Science.gov (United States)

    Gillham, J. K.; Stadnicki, S. J.; Hazony, Y.

    1974-01-01

    The torsional braid experiment has been interfaced with a centralized hierarchical computing system for data acquisition and data processing. Such a system, when matched by the appropriate upgrading of the monitoring techniques, provides high resolution thermomechanical spectra of rigidity and damping, and their derivatives with respect to temperature.

  17. Thermomechanical characterization of joints for blanket and divertor application processed by electrochemical plating

    Energy Technology Data Exchange (ETDEWEB)

    Krauss, Wolfgang; Lorenz, Julia; Konys, Jürgen; Basuki, Widodo; Aktaa, Jarir

    2016-11-01

    Highlights: • Electroplating is a relevant technology for brazing of blanket and divertor parts. • Tungsten, Eurofer and steel joints successfully fabricated. • Reactive interlayers improve adherence and reduce failure risks. • Qualification of joints performed by thermo-mechanical testing and aging. • Shear strength of joints comparable with conventionally brazing of steels. - Abstract: Fusion technology requires in the fields of first wall and divertor development reliable and adjusted joining processes of plasma facing tungsten to heat sinks or blanket structures. The components to be bonded will be fabricated from tungsten, steel or other alloys like copper. The parts have to be joined under functional and structural aspects considering the metallurgical interactions of alloys to be assembled and the filler materials. Application of conventional brazing showed lacks ranging from bad wetting of tungsten up to embrittlement of fillers and brazing zones. Thus, the deposition of reactive interlayers and filler components, e.g. Ni, Pd or Cu was initiated to overcome these metallurgical restrictions and to fabricate joints with aligned mechanical behavior. This paper presents results concerning the joining of tungsten, Eurofer and stainless steel for blanket and divertor application by applying electroplating technology. Metallurgical and mechanical characterization by shear testing were performed to analyze the joints quality and application limits in dependence on testing temperature between room temperature and 873 K and after thermal aging of up to 2000 h. The tested interlayers Ni and Pd enhanced wetting and enabled the processing of reliable joints with a shear strength of more than 200 MPa at RT.

  18. Thermal stress analysis and thermo-mechanical fatigue for gas turbine blade

    International Nuclear Information System (INIS)

    Hyun, J. S.; Kim, B. S.; Kang, M. S.; Ha, J. S.; Lee, Y. S.

    2002-01-01

    The numerical analysis for gas turbine blades were carried out under several conditions by compounding temperature field, velocity field, thermal conduction of blade, and cooling heat transfer. The three types of 1,100 deg. C class 1st-stage gas turbine blades were analyzed. The analysis results are applied to the study on evaluating the remaining life for thermo-mechanical fatigue life. The thermo-mechanical fatigue experiments under out-of-phase and in-phase have been performed. The physical-based life prediction models which considered the contribution of different damage mechanisms have been applied. These models were applied to the temperature and strain rate dependences of isothermal cycling fatigue lives, and the strain-temperature history effect on the thermo-mechanical fatigue lives

  19. Global thermo-mechanical effects from a KBS-3 type repository. Summary report

    International Nuclear Information System (INIS)

    Hakami, E.; Olofsson, Stig-Olof; Hakami, H.; Israelsson, Jan

    1998-04-01

    The objective of this study has been to identify the global thermomechanical effects in the bedrock hosting a nuclear waste repository - i.e. the effects at large distances from the repository. Numerical thermomechanical modeling was performed in several steps, beginning with elastic continuum models and followed by distinct element models (3DEC), in which fracture zones are explicitly simulated. The number of fracture zones, the heat intensity of the waste, the material properties of the rock mass and the boundary conditions of the models were varied in different simulations. The results from the numerical modeling show that the principal stresses increase near the repository. The maximum stress obtained for the main model is 44 MPa and occurs at the repository level after about 100 years of deposition. Due to thermal expansion, the rock mass displaces upward, and the maximum heave at the ground surface after 1000 years is calculated to be 16 cm. In the area close to the ground surface, above the center of the repository, the horizontal stresses reduce, causing the rock to yield in tension down to a depth of about 80 m. In correspondence with the stress changes, the fracture zones show opening normal displacements at shallow depths and closing normal displacements and shearing at the repository level. The maximum displacements of the different fracture zones are 0.3-2.5 cm for closing, 0.0-0.8 cm for opening and 0.2-2.2 cm for shearing. Another important input parameter for the analysis is the Young's modulus of the rock mass. In the main model, a value of 30 GPa is assumed. Higher values of Young's modulus give larger thermo-mechanical effects. Other changes of the properties considered give minor changes of the rock mass behavior. All multi-level repository layouts give rise to higher temperatures than the single-level layout, causing the compressive stresses to increase more at the repository level. Fracture zone displacements caused by different layouts are

  20. Damage behavior of SnAgCu/Cu solder joints subjected to thermomechanical cycling

    International Nuclear Information System (INIS)

    Xiao, H.; Li, X.Y.; Hu, Y.; Guo, F.; Shi, Y.W.

    2013-01-01

    Highlights: •A creep–fatigue damage model based on CDM was proposed. •Designed system includes load frame, strain measure device and damage test device. •Damage evolution of solder joints was a function of accumulated inelastic strain. •Damage of solder joints is an interaction between creep and low-cycle fatigue. -- Abstract: Thermomechanical fatigue damage is a progressive process of material degradation. The objective of this study was to investigate the damage behavior of SnAgCu/Cu solder joints under thermomechanical cycling. A damage model was proposed based on continuum damage mechanics (CDM). Based upon an analysis of displacements for flip-chip solder joints subjected to thermal cycling, a special bimetallic loading frame with single-solder joint samples was designed to simulate the service conditions of actual joints in electronic packages. The assembly, which allowed for strain measurements of an individual solder joint during temperature cycling, was used to investigate the impact of stress–strain cycling on the damage behavior of SnAgCu/Cu solder joints. The characteristic parameters of the damage model were determined through thermomechanical cycling and strain measurement tests. The damage variable D = 1 − R 0 /R was selected, and values for it were obtained using a four-probe method for the single-solder joint samples every dozen cycles during thermomechanical cycling tests to verify the model. The results showed that the predicted damage was in good agreement with the experimental results. The damage evolution law proposed here is a function of inelastic strain, and the results showed that the damage rate of SnAgCu/Cu solder joints increased as the range of the applied strain increased. In addition, the microstructure evolution of the solder joints was analyzed using scanning electron microscopy, which provided the microscopic explanation for the damage evolution law of SnAgCu/Cu solder joints

  1. Damage behavior of SnAgCu/Cu solder joints subjected to thermomechanical cycling

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, H., E-mail: xiaohui2013@yahoo.com.cn; Li, X.Y.; Hu, Y.; Guo, F.; Shi, Y.W.

    2013-11-25

    Highlights: •A creep–fatigue damage model based on CDM was proposed. •Designed system includes load frame, strain measure device and damage test device. •Damage evolution of solder joints was a function of accumulated inelastic strain. •Damage of solder joints is an interaction between creep and low-cycle fatigue. -- Abstract: Thermomechanical fatigue damage is a progressive process of material degradation. The objective of this study was to investigate the damage behavior of SnAgCu/Cu solder joints under thermomechanical cycling. A damage model was proposed based on continuum damage mechanics (CDM). Based upon an analysis of displacements for flip-chip solder joints subjected to thermal cycling, a special bimetallic loading frame with single-solder joint samples was designed to simulate the service conditions of actual joints in electronic packages. The assembly, which allowed for strain measurements of an individual solder joint during temperature cycling, was used to investigate the impact of stress–strain cycling on the damage behavior of SnAgCu/Cu solder joints. The characteristic parameters of the damage model were determined through thermomechanical cycling and strain measurement tests. The damage variable D = 1 − R{sub 0}/R was selected, and values for it were obtained using a four-probe method for the single-solder joint samples every dozen cycles during thermomechanical cycling tests to verify the model. The results showed that the predicted damage was in good agreement with the experimental results. The damage evolution law proposed here is a function of inelastic strain, and the results showed that the damage rate of SnAgCu/Cu solder joints increased as the range of the applied strain increased. In addition, the microstructure evolution of the solder joints was analyzed using scanning electron microscopy, which provided the microscopic explanation for the damage evolution law of SnAgCu/Cu solder joints.

  2. Study of Carbide Evolution During Thermo-Mechanical Processing of AISI D2 Tool Steel

    Science.gov (United States)

    Bombac, D.; Fazarinc, M.; Podder, A. Saha; Kugler, G.

    2013-03-01

    The microstructure of a cold-worked tool steel (AISI D2) with various thermo-mechanical treatments was examined in the current study to identify the effects of these treatments on phases. X-ray diffraction was used to identify phases. Microstructural changes such as spheroidization and coarsening of carbides were studied. Thermodynamic calculations were used to verify the results of the differential thermal analysis. It was found that soaking temperature and time have a large influence on dissolution, precipitation, spheroidization, and coalescence of carbides present in the steel. This consequently influences the hot workability and final properties.

  3. Thermomechanical properties of radiation hardened oligoesteracrylates

    International Nuclear Information System (INIS)

    Lomonosova, N.V.; Chikin, Yu.A.

    1984-01-01

    Thermomechanical properties of radiation hardened oligoesteracrylates are studied by the methods of isothermal heating and thermal mechanics. Films of dimethacrylate of ethylene glycol, triethylene glycol (TGM-3), tetraethylene glycol, tridecaethylene glycol and TGM-3 mixture with methyl methacrylate hardened by different doses (5-150 kGy) using Co 60 installation with a dose rate of 2x10 -3 kGy/s served as a subject of the research. During oligoesteracrylate hargening a space network is formed, chain sections between lattice points of which are in a stressed state. Maximum of deformation is observed at 210-220 deg C on thermomechanical curves of samples hardened by doses > 5 kGy, which form and intensity is dependent on an absorbed dose. Presence of a high-temperature maximum on diaqrams of isometric heating of spatially cross-linked oligoesteracrylates is discovered. High thermal stability of three-dimensional network of radiation hardened oligoesteracrylates provides satisfactory tensile properties (40% of initial strength) in sample testing an elevated temperatures (200-250 deg C)

  4. Effect of Thermomechanical Treatment on the Environmentally Induced Cracking Behavior of AA7075 Alloy

    Science.gov (United States)

    Ghosh, Rahul; Venugopal, A.; Sankaravelayudham, P.; Panda, Rajiv; Sharma, S. C.; George, Koshy M.; Raja, V. S.

    2015-02-01

    The influence of thermomechanical treatment on the stress corrosion cracking behavior of AA7075 aluminum alloy forgings was examined in 3.5% NaCl solution by varying the extent of thermomechanical working imparted to each of the conditions. The results show that inadequate working during billet processing resulted in inferior corrosion and mechanical properties. However, more working with intermediate pre-heating stages also led to precipitation of coarse particles resulting in lowering of mechanical properties marginally and a significant reduction in the general/pitting corrosion resistance. The results obtained in the present study indicate that optimum working with controlled pre-heating levels is needed during forging to achieve the desired properties. It is also demonstrated that AA7075 in the over aged condition does not show any environmental cracking susceptibility in spite of the microstructural variations in terms of size and volume fraction of the precipitates. However, the above microstructural variations definitely affected the pitting corrosion and mechanical properties significantly and hence a strict control over the working and pre-heating stages during billet processing is suggested.

  5. Effect of ballistic electrons on ultrafast thermomechanical responses of a thin metal film

    International Nuclear Information System (INIS)

    Xiong Qi-lin; Tian Xin

    2017-01-01

    The ultrafast thermomechanical coupling problem in a thin gold film irradiated by ultrashort laser pulses with different electron ballistic depths is investigated via the ultrafast thermoelasticity model. The solution of the problem is obtained by solving finite element governing equations. The comparison between the results of ultrafast thermomechanical coupling responses with different electron ballistic depths is made to show the ballistic electron effect. It is found that the ballistic electrons have a significant influence on the ultrafast thermomechanical coupling behaviors of the gold thin film and the best laser micromachining results can be achieved by choosing the specific laser technology (large or small ballistic range). In addition, the influence of simplification of the ultrashort laser pulse source on the results is studied, and it is found that the simplification has a great influence on the thermomechanical responses, which implies that care should be taken when the simplified form of the laser source term is applied as the Gaussian heat source. (paper)

  6. Thermo-mechanical behavior of power electronic packaging assemblies: From characterization to predictive simulation of lifetimes

    Science.gov (United States)

    Dalverny, O.; Alexis, J.

    2018-02-01

    This article deals with thermo-mechanical behavior of power electronic modules used in several transportation applications as railway, aeronautic or automotive systems. Due to a multi-layered structures, involving different materials with a large variation of coefficient of thermal expansion, temperature variations originated from active or passive cycling (respectively from die dissipation or environmental constraint) induces strain and stresses field variations, giving fatigue phenomenon of the system. The analysis of the behavior of these systems and their dimensioning require the implementation of complex modeling strategies by both the multi-physical and the multi-scale character of the power modules. In this paper we present some solutions for studying the thermomechanical behavior of brazed assemblies as well as taking into account the interfaces represented by the numerous metallizations involved in the process assembly.

  7. The Material Supply Adjustment Process in RAMF-SM, Step 2

    Science.gov (United States)

    2016-06-01

    I N S T I T U T E F O R D E F E N S E A N A L Y S E S The Material Supply Adjustment Process in RAMF-SM, Step 2 Eleanor L. Schwartz James S...5564 The Material Supply Adjustment Process in RAMF-SM, Step 2 Eleanor L. Schwartz James S. Thomason, Project Leader This page is intentionally blank...9 1. Inputs and Outputs .......................................................................................10 2. Specific Steps of the PEAP

  8. Effective thermo-mechanical properties and shape memory effect of CNT/SMP composites

    Science.gov (United States)

    Yang, Qingsheng; Liu, Xia; Leng, Fangfang

    2009-07-01

    Shape memory polymer (SMP) has been applied in many fields as intelligent sensors and actuators. In order to improve the mechanical properties and recovery force of SMP, the addition of minor amounts of carbon nanotubes (CNT) into SMP has attracted wide attention. A micromechanical model and thermo-mechanical properties of CNT/SMP composites were studied in this paper. The thermo-mechanical constitutive relation of intellectual composites with isotropic and transversely isotropic CNT was obtained. Moreover, the shape memory effect of CNT/SMP composites and the effect of temperature and the volume fraction of CNT were discussed. The work shows that CNT/SMP composites exhibit excellent macroscopic thermo-mechanical properties and shape memory effect, while both of them can be affected remarkably by temperature and the microstructure parameters.

  9. Mass transport in low permeability rocks under the influence of coupled thermomechanical and hydrochemical effects - an overview

    International Nuclear Information System (INIS)

    Tsang, C.F.

    1984-10-01

    The present paper gives a general overview of mass transport in low permeability rocks under the coupled thermomechanical and hydrochemical effects associated with a nuclear waste repository. A classification of coupled processes is given. Then an ess is presented. example of a coupled process is presented. Discussions of coupled processes based on a recent LBL Panel meeting are summarized. 5 references, 3 figures, 4 tables

  10. PECULIARITIES OF FORMATION OF STRUCTURE AND PROPERTIES AT THERMO-MECHANICAL PROCESSING OF ROLLED WIRE OF NICKEL-MOLYBDENUM STEEL WITH WELDING FUNCTION

    OpenAIRE

    V. A. Lutsenko

    2012-01-01

    There are results of researches of the mechanical properties and structure of the wire rod made of low-carbon nickel molybdenum steel after reduction to toughness thermomechanical treatment in the stream of high-speed wire mill.

  11. Enhanced thermo-mechanical performance and strain-induced ...

    Indian Academy of Sciences (India)

    Enhanced thermo-mechanical performance and strain-induced band gap reduction of TiO2@PVC nanocomposite films ... School of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea; School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea ...

  12. Thermomechanical Modelling of Direct-Drive Friction Welding Applying a Thermal Pseudo Mechanical Model for the Generation of Heat

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Hattel, Jesper Henri

    2018-01-01

    In the present work a 2D a xisymmetric thermomechanical model of the direct-drive friction welding process is developed, taking the temperature dependent shear yield stress into account in the description of the heat generation, utilizing a recent thermal pseudo mechanical model originally...... developed for the friction stir welding (FSW) process. The model is implemented in ABAQUS/Explicit via a subroutine. The application in this case is joining of austenitic stainless steel rods with an outer diameter of 112 mm, used for manufacturing of exhaust gas valves for large two stroke marine engines....... The material properties in terms of the temperature dependent flowstress curves used both in the thermal and the mechanical constitutive description are extracted from compression tests performed between 20 °C and 1200 °C on a Gleeble 1500 thermomechanical simulator. Comparison between measured and simulated...

  13. Thermomechanics of composite structures under high temperatures

    CERN Document Server

    Dimitrienko, Yu I

    2016-01-01

    This pioneering book presents new models for the thermomechanical behavior of composite materials and structures taking into account internal physico-chemical transformations such as thermodecomposition, sublimation and melting at high temperatures (up to 3000 K). It is of great importance for the design of new thermostable materials and for the investigation of reliability and fire safety of composite structures. It also supports the investigation of interaction of composites with laser irradiation and the design of heat-shield systems. Structural methods are presented for calculating the effective mechanical and thermal properties of matrices, fibres and unidirectional, reinforced by dispersed particles and textile composites, in terms of properties of their constituent phases. Useful calculation methods are developed for characteristics such as the rate of thermomechanical erosion of composites under high-speed flow and the heat deformation of composites with account of chemical shrinkage. The author expan...

  14. Phase transformation and mechanical behavior of thermomechanically controlled processed high strength ordnance steel

    International Nuclear Information System (INIS)

    Bandyopadhyay, P.S.; Ghosh, S.K.; Kundu, S.; Chatterjee, S.

    2013-01-01

    A new low carbon titanium and niobium microalloyed steel has been thermomechanically processed in a pilot plant unit. Phase transformation phenomenon of the above steel during continuous cooling has been assessed. Evolution of microstructure and mechanical properties has also been studied at different finish rolling temperatures. A mixture of intragranular ferrite with granular bainite and bainitic ferrite along with inter-lath and intra-lath precipitation of (Ti, Nb)CN particles are the characteristic microstructural feature of air cooled steel. However, mixture of lower bainite and lath martensitic structure along with similar type (Ti, Nb)CN precipitate is observed in water quenched steel. High yield strength (896–948 MPa) with high tensile strength (974–1013 MPa) has been achieved with moderate ductility (16–17%) for the selected range of finish rolling temperature for air cooled steel. However, the water quenched steel yields higher yield strength (1240–1260 MPa) as well as higher tensile strength (1270–1285 MPa) but with lower ductility (13–14%) for the selected range of finish rolling temperature. Fairly good impact toughness values in the range of 50–89 J are obtained for the air cooled steel which are marginally higher than those of water quenched steel (42–81 J). - Highlights: ► New high strength steel has been processed in a pilot plant scale. ► Primarily granular bainite and bainitic ferrite are obtained in air cooled steel. ► Mixture of lower bainite and lath martensite is obtained in water quenched steel. ► (Ti, Nb)CN precipitate is obtained for both air cooled and water quenched steels. ► Highest strength with reasonable ductility has been achieved after water quenching

  15. Phase transformation and mechanical behavior of thermomechanically controlled processed high strength ordnance steel

    Energy Technology Data Exchange (ETDEWEB)

    Bandyopadhyay, P.S. [Ordnance Development Centre, Metal and Steel Factory, Ishapore 743 144 (India); Ghosh, S.K., E-mail: skghosh@metal.becs.ac.in [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India); Kundu, S.; Chatterjee, S. [Department of Metallurgy and Materials Engineering, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India)

    2013-02-15

    A new low carbon titanium and niobium microalloyed steel has been thermomechanically processed in a pilot plant unit. Phase transformation phenomenon of the above steel during continuous cooling has been assessed. Evolution of microstructure and mechanical properties has also been studied at different finish rolling temperatures. A mixture of intragranular ferrite with granular bainite and bainitic ferrite along with inter-lath and intra-lath precipitation of (Ti, Nb)CN particles are the characteristic microstructural feature of air cooled steel. However, mixture of lower bainite and lath martensitic structure along with similar type (Ti, Nb)CN precipitate is observed in water quenched steel. High yield strength (896–948 MPa) with high tensile strength (974–1013 MPa) has been achieved with moderate ductility (16–17%) for the selected range of finish rolling temperature for air cooled steel. However, the water quenched steel yields higher yield strength (1240–1260 MPa) as well as higher tensile strength (1270–1285 MPa) but with lower ductility (13–14%) for the selected range of finish rolling temperature. Fairly good impact toughness values in the range of 50–89 J are obtained for the air cooled steel which are marginally higher than those of water quenched steel (42–81 J). - Highlights: ► New high strength steel has been processed in a pilot plant scale. ► Primarily granular bainite and bainitic ferrite are obtained in air cooled steel. ► Mixture of lower bainite and lath martensite is obtained in water quenched steel. ► (Ti, Nb)CN precipitate is obtained for both air cooled and water quenched steels. ► Highest strength with reasonable ductility has been achieved after water quenching.

  16. Thermomechanical simulations and experimental validation for high speed incremental forming

    Science.gov (United States)

    Ambrogio, Giuseppina; Gagliardi, Francesco; Filice, Luigino; Romero, Natalia

    2016-10-01

    Incremental sheet forming (ISF) consists in deforming only a small region of the workspace through a punch driven by a NC machine. The drawback of this process is its slowness. In this study, a high speed variant has been investigated from both numerical and experimental points of view. The aim has been the design of a FEM model able to perform the material behavior during the high speed process by defining a thermomechanical model. An experimental campaign has been performed by a CNC lathe with high speed to test process feasibility. The first results have shown how the material presents the same performance than in conventional speed ISF and, in some cases, better material behavior due to the temperature increment. An accurate numerical simulation has been performed to investigate the material behavior during the high speed process confirming substantially experimental evidence.

  17. Thermo-mechanical design and testing of a microbalance for space applications

    Science.gov (United States)

    Scaccabarozzi, Diego; Saggin, Bortolino; Tarabini, Marco; Palomba, Ernesto; Longobardo, Andrea; Zampetti, Emiliano

    2014-12-01

    This work focuses on the thermo-mechanical design of the microbalance used for the VISTA (Volatile In Situ Thermogravimetry Analyzer) sensor. VISTA has been designed to operate in situ in different space environments (asteroids, Mars, icy satellites). In this paper we focus on its application on Mars, where the expected environmental conditions are the most challenging for the thermo-mechanical design. The microbalance holding system has been designed to ensure piezoelectric crystal integrity against the high vibration levels during launch and landing and to cope with the unavoidable thermo-elastic differential displacements due to CTE and temperature differences between the microbalance elements. The crystal holding system, based on three symmetrical titanium supports, provides also the electrical connections needed for crystal actuation, microbalance heating and temperature measurement on the electrode area. On the microbalance crystal surfaces the electrodes, a micro film heater (optimized to perform thermo-gravimetric analysis up to 400 °C) and a resistive thermometer are deposited through a vacuum sputtering process. A mockup of the system has been manufactured and tested at the expected vibration levels and the thermal control effectiveness has been verified in thermo-vacuum environment.

  18. Method of manufacturing iron aluminide by thermomechanical processing of elemental powders

    Science.gov (United States)

    Deevi, Seetharama C.; Lilly, Jr., A. Clifton; Sikka, Vinod K.; Hajaligol, Mohammed R.

    2000-01-01

    A powder metallurgical process of preparing iron aluminide useful as electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 20 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1 % rare earth metal, .ltoreq.1% oxygen, and/or .ltoreq.3% Cu. The process includes forming a mixture of aluminum powder and iron powder, shaping the mixture into an article such as by cold rolling the mixture into a sheet, and sintering the article at a temperature sufficient to react the iron and aluminum powders and form iron aluminide. The sintering can be followed by hot or cold rolling to reduce porosity created during the sintering step and optional annealing steps in a vacuum or inert atmosphere.

  19. A multiscale finite element method for modeling fully coupled thermomechanical problems in solids

    KAUST Repository

    Sengupta, Arkaprabha; Papadopoulos, Panayiotis; Taylor, Robert L.

    2012-01-01

    This article proposes a two-scale formulation of fully coupled continuum thermomechanics using the finite element method at both scales. A monolithic approach is adopted in the solution of the momentum and energy equations. An efficient implementation of the resulting algorithm is derived that is suitable for multicore processing. The proposed method is applied with success to a strongly coupled problem involving shape-memory alloys. © 2012 John Wiley & Sons, Ltd.

  20. A multiscale finite element method for modeling fully coupled thermomechanical problems in solids

    KAUST Repository

    Sengupta, Arkaprabha

    2012-05-18

    This article proposes a two-scale formulation of fully coupled continuum thermomechanics using the finite element method at both scales. A monolithic approach is adopted in the solution of the momentum and energy equations. An efficient implementation of the resulting algorithm is derived that is suitable for multicore processing. The proposed method is applied with success to a strongly coupled problem involving shape-memory alloys. © 2012 John Wiley & Sons, Ltd.

  1. PECULIARITIES OF FORMATION OF STRUCTURE AND PROPERTIES AT THERMO-MECHANICAL PROCESSING OF ROLLED WIRE OF NICKEL-MOLYBDENUM STEEL WITH WELDING FUNCTION

    Directory of Open Access Journals (Sweden)

    V. A. Lutsenko

    2012-01-01

    Full Text Available There are results of researches of the mechanical properties and structure of the wire rod made of low-carbon nickel molybdenum steel after reduction to toughness thermomechanical treatment in the stream of high-speed wire mill.

  2. Best estimate modeling of fuel thermomechanical behaviour in WWER 1000 LB LOCA

    International Nuclear Information System (INIS)

    Valach, M.; Klouzal, J.; Zymak, J.; Dostal, M.

    2009-01-01

    The paper summarizes our calculations of the performance of the WWER 1000 NPP fuel rods during postulated LB LOCA. The thermomechanical modeling was performed by FRAPTRAN using the FRACAS-I mechanical model using the boundary conditions calculated by the ATHLET code. The results and their statistical evaluation are presented, the process of the generalization of gained insight into the best-estimate thermal-hydraulic analyses (BE TM) predictions in order to define a generic BE TM methodology is outlined (authors)

  3. Thermomechanical behavior of a two-way shape memory composite actuator

    International Nuclear Information System (INIS)

    Ge, Qi; Westbrook, Kristofer K; Dunn, Martin L; Jerry Qi, H; Mather, Patrick T

    2013-01-01

    Shape memory polymers (SMPs) are a class of smart materials that can fix a temporary shape and recover to their permanent (original) shape in response to an environmental stimulus such as heat, electricity, or irradiation, among others. Most SMPs developed in the past can only demonstrate the so-called one-way shape memory effect; i.e., one programming step can only yield one shape memory cycle. Recently, one of the authors (Mather) developed a SMP that exhibits both one-way shape memory (1W-SM) and two-way shape memory (2W-SM) effects (with the assistance of an external load). This SMP was further used to develop a free-standing composite actuator with a nonlinear reversible actuation under thermal cycling. In this paper, a theoretical model for the PCO SMP based composite actuator was developed to investigate its thermomechanical behavior and the mechanisms for the observed phenomena during the actuation cycles, and to provide insight into how to improve the design. (paper)

  4. Method of manufacturing aluminide sheet by thermomechanical processing of aluminide powders

    Science.gov (United States)

    Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

    2000-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr.ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  5. The partner selection process : Steps, effectiveness, governance

    NARCIS (Netherlands)

    Duisters, D.; Duijsters, G.M.; de Man, A.P.

    2011-01-01

    Selecting the right partner is important for creating value in alliances. Even though prior research suggests that a structured partner selection process increases alliance success, empirical research remains scarce. This paper presents an explorative empirical study that shows that some steps in

  6. The partner selection process : steps, effectiveness, governance

    NARCIS (Netherlands)

    Duisters, D.; Duysters, G.M.; Man, de A.P.

    2011-01-01

    Selecting the right partner is important for creating value in alliances. Even though prior research suggests that a structured partner selection process increases alliance success, empirical research remains scarce. This paper presents an explorative empirical study that shows that some steps in

  7. On-chip detection of gel transition temperature using a novel micro-thermomechanical method.

    Directory of Open Access Journals (Sweden)

    Tsenguun Byambadorj

    Full Text Available We present a new thermomechanical method and a platform to measure the phase transition temperature at microscale. A thin film metal sensor on a membrane simultaneously measures both temperature and mechanical strain of the sample during heating and cooling cycles. This thermomechanical principle of operation is described in detail. Physical hydrogel samples are prepared as a disc-shaped gels (200 μm thick and 1 mm diameter and placed between an on-chip heater and sensor devices. The sol-gel transition temperature of gelatin solution at various concentrations, used as a model physical hydrogel, shows less than 3% deviation from in-depth rheological results. The developed thermomechanical methodology is promising for precise characterization of phase transition temperature of thermogels at microscale.

  8. Two scale damage model and related numerical issues for thermo-mechanical high cycle fatigue

    International Nuclear Information System (INIS)

    Desmorat, R.; Kane, A.; Seyedi, M.; Sermage, J.P.

    2007-01-01

    On the idea that fatigue damage is localized at the microscopic scale, a scale smaller than the mesoscopic one of the Representative Volume Element (RVE), a three-dimensional two scale damage model has been proposed for High Cycle Fatigue applications. It is extended here to aniso-thermal cases and then to thermo-mechanical fatigue. The modeling consists in the micro-mechanics analysis of a weak micro-inclusion subjected to plasticity and damage embedded in an elastic meso-element (the RVE of continuum mechanics). The consideration of plasticity coupled with damage equations at micro-scale, altogether with Eshelby-Kroner localization law, allows to compute the value of microscopic damage up to failure for any kind of loading, 1D or 3D, cyclic or random, isothermal or aniso-thermal, mechanical, thermal or thermo-mechanical. A robust numerical scheme is proposed in order to make the computations fast. A post-processor for damage and fatigue (DAMAGE-2005) has been developed. It applies to complex thermo-mechanical loadings. Examples of the representation by the two scale damage model of physical phenomena related to High Cycle Fatigue are given such as the mean stress effect, the non-linear accumulation of damage. Examples of thermal and thermo-mechanical fatigue as well as complex applications on real size testing structure subjected to thermo-mechanical fatigue are detailed. (authors)

  9. Thermomechanical evaluation of the fuel assemblies fabricated in the ININ

    International Nuclear Information System (INIS)

    Hernandez L, H.; Ortiz V, J.

    2005-01-01

    The pilot plant of fuel production of the National Institute of Nuclear Research (ININ) provided to the Laguna Verde Nuclear Power Plant (CNLV) four fuel assemblies type GE9B. The fuel irradiation was carried out in the unit 1 of the CNLV during four operation cycles, highlighting the fact that in their third cycle the four assemblies were placed in the center of the reactor core. In the Nuclear Systems Department (DSN) of the ININ it has been carried out studies to evaluate their neutron performance and to be able to determine the exposure levels of this fuels. Its also outlines the necessity to carry out a study of the thermomechanical behavior of the fuel rods that compose the assemblies, through computational codes that simulate their performance so much thermal as mechanical. For such purpose has been developing in the DSN the FETMA code, together with the codes that compose the system Fuel Management System (FMS), which evaluates the thermomechanical performance of fuel elements. In this work were used the FETMA and FEMAXI codes (developed by JAERI) to study the thermomechanical performance of the fuel elements manufactured in the ININ. (Author)

  10. Lyondell develops one step isobutylene process

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This paper reports that Lyondell Petrochemical Co., Houston, has developed a one step process to convert normal butylenes to isobutylene, a key component of methyl tertiary butyl ether (MTBE). MTBE is expected to become the additive of choice among U.S. refiners to blend oxygenated gasolines required by 1990 amendments to the Clean Air Act. Lyondell Pres. and Chief Executive Officer Bob Gower the the new process could help assure adequate supplies of MTBE to meet U.S. demand for cleaner burning fuels. Lyondell estimates the capital cost of building a grassroots plant to produce isobutylene with the new process would be less than half the cost of a grassroot plant to produce isobutylene with existing technology starting with normal butane

  11. Numerical simulation of machining distortions on a forged aerospace component following a one and a multi-step approaches

    Science.gov (United States)

    Prete, Antonio Del; Franchi, Rodolfo; Antermite, Fabrizio; Donatiello, Iolanda

    2018-05-01

    Residual stresses appear in a component as a consequence of thermo-mechanical processes (e.g. ring rolling process) casting and heat treatments. When machining these kinds of components, distortions arise due to the redistribution of residual stresses due to the foregoing process history inside the material. If distortions are excessive, they can lead to a large number of scrap parts. Since dimensional accuracy can affect directly the engines efficiency, the dimensional control for aerospace components is a non-trivial issue. In this paper, the problem related to the distortions of large thin walled aeroengines components in nickel superalloys has been addressed. In order to estimate distortions on inner diameters after internal turning operations, a 3D Finite Element Method (FEM) analysis has been developed on a real industrial test case. All the process history, has been taken into account by developing FEM models of ring rolling process and heat treatments. Three different strategies of ring rolling process have been studied and the combination of related parameters which allows to obtain the best dimensional accuracy has been found. Furthermore, grain size evolution and recrystallization phenomena during manufacturing process has been numerically investigated using a semi empirical Johnson-Mehl-Avrami-Kohnogorov (JMAK) model. The volume subtractions have been simulated by boolean trimming: a one step and a multi step analysis have been performed. The multi-step procedure has allowed to choose the best material removal sequence in order to reduce machining distortions.

  12. Development of low enriched uranium target plates by thermo-mechanical processing of UAl2–Al matrix for production of 99Mo in Pakistan

    International Nuclear Information System (INIS)

    Ali, Kanwar Liaqat; Khan, Akhlaque Ahmad; Mushtaq, Ahmad; Imtiaz, Farhan; Ziai, Maratab Ali; Gulzar, Amir; Farooq, Muhammad; Hussain, Nazar; Ahmed, Nisar; Pervez, Shahid; Zaidi, Jamshed Hussain

    2013-01-01

    Uranium aluminide predominated with UAl 2 phase was prepared by arc-melting procedures and comminuted to required particle size. UAl 2 and Al powders were blended and compacted to achieve LEU fuel density of 2.17 g/cm 3 . The picture-frame technique was used to clad the dispersions (UAl 2 –Al) with aluminum. A few target plates were fabricated by thermo-mechanical processing (hot rolling and annealing) of UAl 2 –Al matrix contained in roll billet of Al. The fabricated plates were characterized by destructive and some of non-destructive testing techniques and then annealed to achieve required phase of uranium aluminide for proper dissolution in basic media

  13. Thermomechanical modelling of laser surface glazing for H13 tool steel

    Science.gov (United States)

    Kabir, I. R.; Yin, D.; Tamanna, N.; Naher, S.

    2018-03-01

    A two-dimensional thermomechanical finite element (FE) model of laser surface glazing (LSG) has been developed for H13 tool steel. The direct coupling technique of ANSYS 17.2 (APDL) has been utilised to solve the transient thermomechanical process. A H13 tool steel cylindrical cross-section has been modelled for laser power 200 W and 300 W at constant 0.2 mm beam width and 0.15 ms residence time. The model can predict temperature distribution, stress-strain increments in elastic and plastic region with time and space. The crack formation tendency also can be assumed by analysing the von Mises stress in the heat-concentrated zone. Isotropic and kinematic hardening models have been applied separately to predict the after-yield phenomena. At 200 W laser power, the peak surface temperature achieved is 1520 K which is below the melting point (1727 K) of H13 tool steel. For laser power 300 W, the peak surface temperature is 2523 K. Tensile residual stresses on surface have been found after cooling, which are in agreement with literature. Isotropic model shows higher residual stress that increases with laser power. Conversely, kinematic model gives lower residual stress which decreases with laser power. Therefore, both plasticity models could work in LSG for H13 tool steel.

  14. Interfacial characteristics of hybrid nanocomposite under thermomechanical loading

    Science.gov (United States)

    Choyal, Vijay; Kundalwal, Shailesh I.

    2017-12-01

    In this work, an improved shear lag model was developed to investigate the interfacial characteristics of three-phase hybrid nanocomposite which is reinforced with microscale fibers augmented with carbon nanotubes on their circumferential surfaces. The shear lag model accounts for (i) radial and axial deformations of different transversely isotropic constituents, (ii) thermomechanical loads on the representative volume element (RVE), and (iii) staggering effect of adjacent RVEs. The results from the current newly developed shear lag model are validated with the finite element simulations and found to be in good agreement. This study reveals that the reduction in the maximum value of the axial stress in the fiber and the interfacial shear stress along its length become more pronounced in the presence of applied thermomechanical loads on the staggered RVEs. The existence of shear tractions along the RVE length plays a significant role in the interfacial characteristics and cannot be ignored.

  15. Poly-Lactide/Exfoliated C30B Interactions and Influence on Thermo-Mechanical Properties Due to Artificial Weathering

    Directory of Open Access Journals (Sweden)

    Wendy Margarita Chávez-Montes

    2016-04-01

    Full Text Available Thermal stability as well as enhanced mechanical properties of poly-lactide (PLA can increase PLA applications for short-use products. The conjunction of adequate molecular weight (MW as well as satisfactory thermo-mechanical properties, together, can lead to the achievement of suitable properties. However, PLA is susceptible to thermal degradation and thus an undesired decay of MW and a decrease of its mechanical properties during processing. To avoid this PLA degradation, nanofiller is incorporated as reinforcement to increase its thermo-mechanical properties. There are many papers focusing on filler effects on the thermal stability and mechanical properties of PLA/nanocomposites; however, these investigations lack an explanation of polymer/filler interactions. We propose interactions between PLA and Cloisite30B (C30B as nanofiller. We also study the effects on the thermal and mechanical properties due to molecular weight decay after exposure to artificial weathering. PLA blank and nanocomposites were subjected to three time treatments (0, 176, and 360 h of exposure to artificial weathering in order to achieve comparable materials with different MW. MW was acquired by means of Gel Permeation Chromatography (GPC. Thermo-mechanical properties were investigated through Thermogravimetric Analysis (TGA, Differential Scanning Calorimetry (DSC, X-ray Diffraction (XRD, Dynamic Mechanical Thermal Analysis (DMTA and Fourier Transform Infrared Spectroscopy (FTIR.

  16. Design and fabrication of a chitosan hydrogel with gradient structures via a step-by-step cross-linking process.

    Science.gov (United States)

    Xu, Yongxiang; Yuan, Shenpo; Han, Jianmin; Lin, Hong; Zhang, Xuehui

    2017-11-15

    The development of scaffolds to mimic the gradient structure of natural tissue is an important consideration for effective tissue engineering. In the present study, a physical cross-linking chitosan hydrogel with gradient structures was fabricated via a step-by-step cross-linking process using sodium tripolyphosphate and sodium hydroxide as sequential cross-linkers. Chitosan hydrogels with different structures (single, double, and triple layers) were prepared by modifying the gelling process. The properties of the hydrogels were further adjusted by varying the gelling conditions, such as gelling time, pH, and composition of the crosslinking solution. Slight cytotoxicity was showed in MTT assay for hydrogels with uncross-linking chitosan solution and non-cytotoxicity was showed for other hydrogels. The results suggest that step-by-step cross-linking represents a practicable method to fabricate scaffolds with gradient structures. Copyright © 2017. Published by Elsevier Ltd.

  17. Coupled thermomechanical behavior of graphene using the spring-based finite element approach

    Energy Technology Data Exchange (ETDEWEB)

    Georgantzinos, S. K., E-mail: sgeor@mech.upatras.gr; Anifantis, N. K., E-mail: nanif@mech.upatras.gr [Machine Design Laboratory, Department of Mechanical Engineering and Aeronautics, University of Patras, Rio, 26500 Patras (Greece); Giannopoulos, G. I., E-mail: ggiannopoulos@teiwest.gr [Materials Science Laboratory, Department of Mechanical Engineering, Technological Educational Institute of Western Greece, 1 Megalou Alexandrou Street, 26334 Patras (Greece)

    2016-07-07

    The prediction of the thermomechanical behavior of graphene using a new coupled thermomechanical spring-based finite element approach is the aim of this work. Graphene sheets are modeled in nanoscale according to their atomistic structure. Based on molecular theory, the potential energy is defined as a function of temperature, describing the interatomic interactions in different temperature environments. The force field is approached by suitable straight spring finite elements. Springs simulate the interatomic interactions and interconnect nodes located at the atomic positions. Their stiffness matrix is expressed as a function of temperature. By using appropriate boundary conditions, various different graphene configurations are analyzed and their thermo-mechanical response is approached using conventional finite element procedures. A complete parametric study with respect to the geometric characteristics of graphene is performed, and the temperature dependency of the elastic material properties is finally predicted. Comparisons with available published works found in the literature demonstrate the accuracy of the proposed method.

  18. Thermomechanical characterization of thiol-epoxy shape memory thermosets for mechanical actuators design

    Science.gov (United States)

    Belmonte, Alberto; Fernández-Francos, Xavier; De la Flor, Silvia

    2018-02-01

    In this paper, shape-memory "thiol-epoxy" polymers are synthesized and characterized as potential thermomechanical actuators. Their thermomechanical properties are investigated through dynamo mechanical and tensile analyses and related to their network structural properties by using "thiol" and "epoxy" compounds of different functionality and structure. Their mechanical properties (resistance at break, elongation limits and strain energy) are related to their shape-memory response under free-recovery conditions and partially-constrained conditions, thus, establishing the connection between network relaxation (free-recovery) with the work output capabilities (partially-constrained). Results show high mechanical performance, achieving high elongation at break values (up to 100%) and stress at break values (up to 50 MPa). The shape-memory experiments reveal strong dependence of the programming conditions and network structure on the recovery efficiency at free-conditions, whereas under partially-constrained conditions, the controlling factors are the mechanical limits at high temperature. Moreover, some recommendations to achieve the maximum work output efficiency for a given operational design of a thermomechanical actuator are deduced.

  19. Thermomechanics of solid materials with application to the Gurson-Tvergaard material model

    Energy Technology Data Exchange (ETDEWEB)

    Santaoja, K. [VTT Manufacturing Technology, Espoo (Finland). Materials and Structural Integrity

    1997-12-31

    The elastic-plastic material model for porous material proposed by Gurson and Tvergaard is evaluated. First a general description is given of constitutive equations for solid materials by thermomechanics with internal variables. The role and definition of internal variables are briefly discussed and the following definition is given: The independent variables present (possibly hidden) in the basic laws for thermomechanics are called controllable variables. The other independent variables are called internal variables. An internal variable is shown always to be a state variable. This work shows that if the specific dissipation function is a homogeneous function of degree one in the fluxes, a description for a time-independent process is obtained. When damage to materials is evaluated, usually a scalar-valued or tensorial variable called damage is introduced in the set of internal variables. A problem arises when determining the relationship between physically observable weakening of the material and the value for damage. Here a more feasible approach is used. Instead of damage, the void volume fraction is inserted into the set of internal variables. This allows use of an analytical equation for description of the mechanical weakening of the material. An extension to the material model proposed by Gurson and modified by Tvergaard is derived. The derivation is based on results obtained by thermomechanics and damage mechanics. The main difference between the original Gurson-Tvergaard material model and the extended one lies in the definition of the internal variable `equivalent tensile flow stress in the matrix material` denoted by {sigma}{sup M}. Using classical plasticity theory, Tvergaard elegantly derived an evolution equation for {sigma}{sup M}. This is not necessary in the present model, since damage mechanics gives an analytical equation between the stress tensor {sigma} and {sigma}M. Investigation of the Clausius-Duhem inequality shows that in compression

  20. Thermomechanics of solid materials with application to the Gurson-Tvergaard material model

    International Nuclear Information System (INIS)

    Santaoja, K.

    1997-01-01

    The elastic-plastic material model for porous material proposed by Gurson and Tvergaard is evaluated. First a general description is given of constitutive equations for solid materials by thermomechanics with internal variables. The role and definition of internal variables are briefly discussed and the following definition is given: The independent variables present (possibly hidden) in the basic laws for thermomechanics are called controllable variables. The other independent variables are called internal variables. An internal variable is shown always to be a state variable. This work shows that if the specific dissipation function is a homogeneous function of degree one in the fluxes, a description for a time-independent process is obtained. When damage to materials is evaluated, usually a scalar-valued or tensorial variable called damage is introduced in the set of internal variables. A problem arises when determining the relationship between physically observable weakening of the material and the value for damage. Here a more feasible approach is used. Instead of damage, the void volume fraction is inserted into the set of internal variables. This allows use of an analytical equation for description of the mechanical weakening of the material. An extension to the material model proposed by Gurson and modified by Tvergaard is derived. The derivation is based on results obtained by thermomechanics and damage mechanics. The main difference between the original Gurson-Tvergaard material model and the extended one lies in the definition of the internal variable 'equivalent tensile flow stress in the matrix material' denoted by σ M . Using classical plasticity theory, Tvergaard elegantly derived an evolution equation for σ M . This is not necessary in the present model, since damage mechanics gives an analytical equation between the stress tensor σ and σM. Investigation of the Clausius-Duhem inequality shows that in compression, states occur which are not

  1. Application of processing maps in the optimization of the parameters of a hot working process. Part 1. Theoretical review

    International Nuclear Information System (INIS)

    Al Omar, A.; Prado, J.M.

    1997-01-01

    The hot working processes constitute an important step in the manufacture of components for engineering applications. In the past, the mechanical processing have been used to impart a shape to the engineering materials. More recently, however, the hot working processes are used not only to achieve the required shape but also to impart desirable mechanical and microstructural characteristics by an adequate design of the thermomechanical process. The aim of the present paper is to summarize the general characteristics of the Dynamic Materials Model. In this model, the work piece material under hot working conditions is considered to be a dissipator of power. Also, the extreme principles of irreversible thermodynamics applied to large plastic flow are described to develop a continuum criterion capable to predict the metallurgical instabilities in a hot worked material. (Author) 22 refs

  2. Examination of the Thermo-mechanical Properties of E-Glass/Carbon Composites

    Directory of Open Access Journals (Sweden)

    Hande Sezgin

    2017-12-01

    Full Text Available Eight-ply E-glass, carbon and E-glass/carbon fabric-reinforced polyester based hybrid composites were manufactured in this study. A vacuum infusion system was used as the production method. Dynamic mechanical analysis, thermogravimetric analysis and differential scanning calorimetry analysis were conducted to examine the thermo-mechanical properties of composite samples. The effect of reinforcement type and different stacking sequences of fabric plies on the thermo-mechanical properties of composite samples were also investigated. Results showed that the type and alignment of reinforcement material has a signifi cant effect on the dynamic mechanical properties of composite samples.

  3. Strengthening of stable Cr-Ni austenitic stainless steel under thermomechanical treatments

    Science.gov (United States)

    Akkuzin, S. A.; Litovchenko, I. Yu.; Tyumentsev, A. N.

    2017-12-01

    The features of microstructure and mechanical properties of stable austenitic steel after thermomechanical treatment consisted of low-temperature deformation, deformation in the temperature range T = 273-873 K, and subsequent annealing were investigated. It is shown that under such treatment direct (γ → α')- and reverse (α'→γ)-martensitic transformations occur in the steel. As a result of the thermomechanical treatment submicrocrystalline structural states with high density of micro- and nanotwins and localized deformation bands are formed. The strength of the steel in these structural states is several times higher than that in the initial state.

  4. Effects of Microstructural Variability on Thermo-Mechanical Properties of a Woven Ceramic Matrix Composite

    Science.gov (United States)

    Goldsmith, Marlana B.; Sankar, Bhavani V.; Haftka, Raphael T.; Goldberg, Robert K.

    2013-01-01

    The objectives of this paper include identifying important architectural parameters that describe the SiC/SiC five-harness satin weave composite and characterizing the statistical distributions and correlations of those parameters from photomicrographs of various cross sections. In addition, realistic artificial cross sections of a 2D representative volume element (RVE) are generated reflecting the variability found in the photomicrographs, which are used to determine the effects of architectural variability on the thermo-mechanical properties. Lastly, preliminary information is obtained on the sensitivity of thermo-mechanical properties to architectural variations. Finite element analysis is used in combination with a response surface and it is shown that the present method is effective in determining the effects of architectural variability on thermo-mechanical properties.

  5. Going greener: Synthesis of fully biobased unsaturated polyesters for styrene crosslinked resins with enhanced thermomechanical properties

    Directory of Open Access Journals (Sweden)

    C. S. M. F. Costa

    2017-11-01

    Full Text Available The main goal of this work was the development of fully biobased unsaturated polyesters (UPs that upon crosslinking with unsaturated monomers (UM could lead to greener unsaturated polyester resins (UPRs with similar thermomechanical properties to commercial fossil based UPR. After the successful synthesis of the biobased UPs, those were crosslinked with styrene (Sty, the most commonly used monomer, and the influence of the chemical structure of the UPs on the thermomechanical characteristics of UPRs were evaluated. The properties were compared with those of a commercial resin (Resipur 9837©. The BioUPRs presented high gel contents and contact angles that are similar to the commercial resin. The thermomechanical properties were evaluated by dynamic mechanical thermal analysis (DMTA and it was found that the UPR synthesized using propylene glycol (PG, succinic acid (SuAc and itaconic acid (ItAc presented very close thermomechanical properties compared to the commercial resin.

  6. Thermomechanical behavior modeling and experimental validation of polymer-wound composite multi-layers. Hydrogen storage application

    International Nuclear Information System (INIS)

    Gentilleau, Benoit

    2012-01-01

    The purpose of this research is to study the thermomechanical behavior of the constituent materials of a type IV hydrogen storage tank: a composite, ensuring the strength, is wound around the polyurethane liner that ensures sealing of the tank and thermal insulation; at the extremities, stainless steel parts are used to allow the process connection. In this type of tank, during filling, there is a significant increase in hydrogen temperature, resulting in a gradual heating of the structure and the presence of temperature gradients. The purpose of this study is primarily to characterize the behavior of such a structure when subjects to complex thermomechanical loading. Initially, mechanical and thermal characterization tests have been made over the service life range of temperature of the tank to obtain the necessary data for the realization of a thermomechanical numerical model. Then, a behavior law of the composite, easily transferable to a complex structure such as the whole tank and taking into account the non-linearity, the matrix damage, the progressive loss of shear modulus, and the thermo-dependence of the materials parameters, is developed. The tests on technological representative specimens have been performed to better understand the mechanisms that can appear in the tank and to validate the model. Finally, a numerical study of a tank was performed. The coupled influence of temperature and damage matrix on the behavior of this structure is analyzed. (author)

  7. A multi-step electrochemical etching process for a three-dimensional micro probe array

    International Nuclear Information System (INIS)

    Kim, Yoonji; Youn, Sechan; Cho, Young-Ho; Park, HoJoon; Chang, Byeung Gyu; Oh, Yong Soo

    2011-01-01

    We present a simple, fast, and cost-effective process for three-dimensional (3D) micro probe array fabrication using multi-step electrochemical metal foil etching. Compared to the previous electroplating (add-on) process, the present electrochemical (subtractive) process results in well-controlled material properties of the metallic microstructures. In the experimental study, we describe the single-step and multi-step electrochemical aluminum foil etching processes. In the single-step process, the depth etch rate and the bias etch rate of an aluminum foil have been measured as 1.50 ± 0.10 and 0.77 ± 0.03 µm min −1 , respectively. On the basis of the single-step process results, we have designed and performed the two-step electrochemical etching process for the 3D micro probe array fabrication. The fabricated 3D micro probe array shows the vertical and lateral fabrication errors of 15.5 ± 5.8% and 3.3 ± 0.9%, respectively, with the surface roughness of 37.4 ± 9.6 nm. The contact force and the contact resistance of the 3D micro probe array have been measured to be 24.30 ± 0.98 mN and 2.27 ± 0.11 Ω, respectively, for an overdrive of 49.12 ± 1.25 µm.

  8. Operating experience with the Harwell thermo-mechanical generators

    International Nuclear Information System (INIS)

    Cooke-Yarborough, E.H.

    1980-06-01

    The Stirling-cycle thermo-mechanical generator (TMG) provides small amounts of electrical power continuously over long periods, while requiring much less fuel than other power sources running from hydrocarbon fuel or radio-isotopes. Two of these 25-watt generators, fuelled by propane, have been used to power the UK National Buoy on two successive missions. A total of more than three years experience at sea has now been accumulated. In addition, a 60-watt version has provided the power for a major lighthouse for more than a year. An early development version of the Thermo-mechanical Generator, adapted to run from the heat of a radio-isotope source, was loaded with strontium 90 titanate in October 1974 and has run continuously in the laboratory ever since. The improvements and changes found necessary in the course of 90,000 generator-hours of running time are described, and the improvements in operational performance and reliability which have resulted are outlined. (author)

  9. Thermo-mechanical stress analysis of cryopreservation in cryobags and the potential benefit of nanowarming.

    Science.gov (United States)

    Solanki, Prem K; Bischof, John C; Rabin, Yoed

    2017-06-01

    Cryopreservation by vitrification is the only promising solution for long-term organ preservation which can save tens of thousands of lives across the world every year. One of the challenges in cryopreservation of large-size tissues and organs is to prevent fracture formation due to the tendency of the material to contract with temperature. The current study focuses on a pillow-like shape of a cryobag, while exploring various strategies to reduce thermo-mechanical stress during the rewarming phase of the cryopreservation protocol, where maximum stresses are typically found. It is demonstrated in this study that while the level of stress may generally increase with the increasing amount of CPA filled in the cryobag, the ratio between width and length of the cryobag play a significant role. Counterintuitively, the overall maximum stress is not found when the bag is filled to its maximum capacity (when the filled cryobag resembles a sphere). Parametric investigation suggests that reducing the initial rewarming rate between the storage temperature and the glass transition temperature may dramatically decrease the thermo-mechanical stress. Adding a temperature hold during rewarming at the glass transition temperature may reduce the thermo-mechanical stress in some cases, but may have an adverse effect in other cases. Finally, it is demonstrated that careful incorporation of volumetric heating by means on nanoparticles in an alternating magnetic field, or nanowarming, can dramatically reduce the resulting thermo-mechanical stress. These observations display the potential benefit of a thermo-mechanical design of the cryopreservation protocols in order to prevent structural damage. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Laccase-Catalyzed Surface Modification of Thermo-Mechanical Pulp (TMP) for the Production of Wood Fiber Insulation Boards Using Industrial Process Water

    Science.gov (United States)

    Schubert, Mark; Ruedin, Pascal; Civardi, Chiara; Richter, Michael; Hach, André; Christen, Herbert

    2015-01-01

    Low-density wood fiber insulation boards are traditionally manufactured in a wet process using a closed water circuit (process water). The water of these industrial processes contains natural phenolic extractives, aside from small amounts of admixtures (e.g., binders and paraffin). The suitability of two fungal laccases and one bacterial laccase was determined by biochemical characterization considering stability and substrate spectra. In a series of laboratory scale experiments, the selected commercial laccase from Myceliophtora thermophila was used to catalyze the surface modification of thermo-mechanical pulp (TMP) using process water. The laccase catalyzed the covalent binding of the phenolic compounds of the process water onto the wood fiber surface and led to change of the surface chemistry directly via crosslinking of lignin moieties. Although a complete substitution of the binder was not accomplished by laccase, the combined use of laccase and latex significantly improved the mechanical strength properties of wood fiber boards. The enzymatically-treated TMP showed better interactions with the synthetic binder, as shown by FTIR-analysis. Moreover, the enzyme is extensively stable in the process water and the approach requires no fresh water as well as no cost-intensive mediator. By applying a second-order polynomial model in combination with the genetic algorithm (GA), the required amount of laccase and synthetic latex could be optimized enabling the reduction of the binder by 40%. PMID:26046652

  11. Calculation of the MSD two-step process with the sudden approximation

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Shiro [Tohoku Univ., Sendai (Japan). Dept. of Physics; Kawano, Toshihiko [Kyushu Univ., Advanced Energy Engineering Science, Kasuga, Fukuoka (Japan)

    2000-03-01

    A calculation of the two-step process with the sudden approximation is described. The Green's function which connects the one-step matrix element to the two-step one is represented in {gamma}-space to avoid the on-energy-shell approximation. Microscopically calculated two-step cross sections are averaged together with an appropriate level density to give a two-step cross section. The calculated cross sections are compared with the experimental data, however the calculation still contains several simplifications at this moment. (author)

  12. Model of mechanical properties change of steel during rolling with use of hightemperature thermomechanical treatment

    International Nuclear Information System (INIS)

    Zhadan, V.T.; Gubenko, V.T.; Bernshtejn, M.L.; Binarskij, M.S.

    1975-01-01

    A mathematical model is proposed of changes in the mechanical properties of the steel-50KHGA in the process of rolling with application of a high-temperature thermomechanical treatment (HTTMT). The model accounts for all the main particularities of the structure formation processes during a high temperature deformation of metals and alloys. The nonmonotonic dependence of the steel mechanical properties on the deformation velocity can be presented as a result of a summary effect of three parallel processes on the formation of these properties: hot working, softening and substructural hardening. The mathematical model has been constructed by the iteration method

  13. Thermo-mechanical properties of polystyrene-based shape memory nanocomposites

    NARCIS (Netherlands)

    Xu, B.; Fu, Y.Q.; Ahmad, M.; Luo, J.K.; Huang, W.M.; Kraft, A.; Reuben, R.; Pei, Y.T.; Chen, Zhenguo; Hosson, J.Th.M. De

    2010-01-01

    Shape memory nanocomposites were fabricated using chemically cross-linked polystyrene (PS) copolymer as a matrix and different nanofillers (including alumina, silica and clay) as the reinforcing agents. Their thermo-mechanical properties and shape memory effects were characterized. Experimental

  14. Assessment of thermo-mechanical behavior in CLAM steel first wall structures

    International Nuclear Information System (INIS)

    Liu Fubin; Yao Man

    2012-01-01

    Highlights: ► China Low Activation Martensitic steel (CLAM) as FW the structural material. ► The thermo-mechanical behavior of the FW was analyzed under the condition of normal ITER operation combined effect of plasma heat flux and neutron heating. ► The temperature dependence of the material physical properties of CLAM is summarized. - Abstract: The temperature and strain distributions of the mockup with distinct structural material (SS316L or China Low Activation Martensitic steel (CLAM)) in two-dimensional model were calculated and analyzed, based on a high heat flux (HHF) test recently reported with heat flux of 3.2 MW/m 2 . The calculated temperature and strain results in the first wall (FW), in which SS316L is as the structural material, showed good agreement with HHF test. By substituting CLAM steel for SS316L the contrast analysis indicates that the thermo-mechanical property for CLAM steel is better than that of SS316 at the same condition. Furthermore, the thermo-mechanical behavior of the FW was analyzed under the condition of normal ITER operation combined effect of plasma heat flux and neutron heating.

  15. Assessment of thermo-mechanical behavior in CLAM steel first wall structures

    Energy Technology Data Exchange (ETDEWEB)

    Liu Fubin, E-mail: liufubin_1216@126.com [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning (China); Yao Man, E-mail: yaoman@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning (China)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer China Low Activation Martensitic steel (CLAM) as FW the structural material. Black-Right-Pointing-Pointer The thermo-mechanical behavior of the FW was analyzed under the condition of normal ITER operation combined effect of plasma heat flux and neutron heating. Black-Right-Pointing-Pointer The temperature dependence of the material physical properties of CLAM is summarized. - Abstract: The temperature and strain distributions of the mockup with distinct structural material (SS316L or China Low Activation Martensitic steel (CLAM)) in two-dimensional model were calculated and analyzed, based on a high heat flux (HHF) test recently reported with heat flux of 3.2 MW/m{sup 2}. The calculated temperature and strain results in the first wall (FW), in which SS316L is as the structural material, showed good agreement with HHF test. By substituting CLAM steel for SS316L the contrast analysis indicates that the thermo-mechanical property for CLAM steel is better than that of SS316 at the same condition. Furthermore, the thermo-mechanical behavior of the FW was analyzed under the condition of normal ITER operation combined effect of plasma heat flux and neutron heating.

  16. Thermo-mechanical simulations of early-age concrete cracking with durability predictions

    Science.gov (United States)

    Havlásek, Petr; Šmilauer, Vít; Hájková, Karolina; Baquerizo, Luis

    2017-09-01

    Concrete performance is strongly affected by mix design, thermal boundary conditions, its evolving mechanical properties, and internal/external restraints with consequences to possible cracking with impaired durability. Thermo-mechanical simulations are able to capture those relevant phenomena and boundary conditions for predicting temperature, strains, stresses or cracking in reinforced concrete structures. In this paper, we propose a weakly coupled thermo-mechanical model for early age concrete with an affinity-based hydration model for thermal part, taking into account concrete mix design, cement type and thermal boundary conditions. The mechanical part uses B3/B4 model for concrete creep and shrinkage with isotropic damage model for cracking, able to predict a crack width. All models have been implemented in an open-source OOFEM software package. Validations of thermo-mechanical simulations will be presented on several massive concrete structures, showing excellent temperature predictions. Likewise, strain validation demonstrates good predictions on a restrained reinforced concrete wall and concrete beam. Durability predictions stem from induction time of reinforcement corrosion, caused by carbonation and/or chloride ingress influenced by crack width. Reinforcement corrosion in concrete struts of a bridge will serve for validation.

  17. Thermomechanical modeling and data analysis for heating experiments at Stripa, Sweden

    International Nuclear Information System (INIS)

    Chan, T.; Littlestone, N.; Wan, O.

    1979-11-01

    Comparisons were made between predicted and measured thermomechanical displacements and stresses for in situ heating experiments at a depth of 340 m in a granite body at Stripa, Sweden. We found that taking into account the temperature dependence of the thermal expansion coefficient and the mechanical properties of the rock substantially improves the agreement between theory and experiment. In general, the displacements calculated using laboratory values of rock properties agree better with field data than in the case of stresses. This may be due to the difference between in situ and laboratory rock modulus. The significance of temperature-dependent rock properties and strength to thermomechanical failure is also discussed

  18. Thermomechanical behavior of NiTiPdPt high temperature shape memory alloy springs

    International Nuclear Information System (INIS)

    Nicholson, D E; Vaidyanathan, R; Padula II, S A; Noebe, R D; Benafan, O

    2014-01-01

    Transformation strains in high temperature shape memory alloys (HTSMAs) are generally smaller than for conventional NiTi alloys and can be purposefully limited in cases where stability and repeatability at elevated temperatures are desired. Yet such alloys can still be used in actuator applications that require large strokes when used in the form of springs. Thus there is a need to understand the thermomechanical behavior of shape memory alloy spring actuators, particularly those consisting of alternative alloys. In this work, a modular test setup was assembled with the objective of acquiring stroke, stress, temperature, and moment data in real time during joule heating and forced convective cooling of Ni 19.5 Ti 50.5 Pd 25 Pt 5 HTSMA springs. The spring actuators were subjected to both monotonic axial loading and thermomechanical cycling. The role of rotational constraints (i.e., by restricting rotation or allowing for free rotation at the ends of the springs) on stroke performance was also assessed. Finally, recognizing that evolution in the material microstructure can result in changes in HTSMA spring geometry, the effect of material microstructural evolution on spring performance was examined. This was done by taking into consideration the changes in geometry that occurred during thermomechanical cycling. This work thus provides insight into designing with HTSMA springs and predicting their thermomechanical performance. (paper)

  19. Evaluation of thermo-mechanical properties data of carbon-based plasma facing materials

    International Nuclear Information System (INIS)

    Ulrickson, M.; Barabash, V.R.; Matera, R.; Roedig, M.; Smith, J.J.; Janev, R.K.

    1991-03-01

    This Report contains the proceedings, results and conclusions of the work done and the analysis performed during the IAEA Consultants' Meeting on ''Evaluation of thermo-mechanical properties data of carbon-based plasma facing materials'', convened on December 17-21, 1990, at the IAEA Headquarters in Vienna. Although the prime objective of the meeting was to critically assess the available thermo-mechanical properties data for certain types of carbon-based fusion relevant materials, the work of the meeting went well beyond this task. The meeting participants discussed in depth the scope and structure of the IAEA material properties database, the format of data presentation, the most appropriate computerized system for data storage, retrieval, exchange and management. The existing IAEA ALADDIN system was adopted as a convenient tool for this purpose and specific ALADDIN labelling schemes and dictionaries were established for the material properties data. An ALADDIN formatted test-file for the thermo-physical and thermo-mechanical properties of pyrolytic graphite is appended to this Report for illustrative purposes. (author)

  20. Effect of Water on the Thermo-Mechanical Behavior of Carbon Cloth Phenolic

    Science.gov (United States)

    Sullivan, Roy M.; Stokes, Eric; Baker, Eric H.

    2011-01-01

    The results of thermo-mechanical experiments, which were conducted previously by one of the authors, are reviewed. The strain in the direction normal to the fabric plane was measured as a function of temperature for a variety of initial moisture contents and heating rates. In this paper, the general features of the thermo-mechanical response are discussed and the effect of heating rate and initial moisture content are highlighted. The mechanical interaction between the phenolic polymer and water trapped within its free volumes as the polymer is heated to high temperatures is discussed. An equation for the internal stresses which are generated within the polymer due to trapped water is obtained from the total stress expression for a binary mixture of polymer and water. Numerical solutions for moisture diffusion in the thermo-mechanical experiments were performed and the results of these solutions are presented. The results of the moisture diffusion solutions help to explain the effects of heating rate and moisture content on the strain behavior normal to the fabric plane.

  1. Simulation of dynamic processes when machining transition surfaces of stepped shafts

    Science.gov (United States)

    Maksarov, V. V.; Krasnyy, V. A.; Viushin, R. V.

    2018-03-01

    The paper addresses the characteristics of stepped surfaces of parts categorized as "solids of revolution". It is noted that in the conditions of transition modes during the switch to end surface machining, there is cutting with varied load intensity in the section of the cut layer, which leads to change in cutting force, onset of vibrations, an increase in surface layer roughness, a decrease of size precision, and increased wear of a tool's cutting edge. This work proposes a method that consists in developing a CNC program output code that allows one to process complex forms of stepped shafts with only one machine setup. The authors developed and justified a mathematical model of a technological system for mechanical processing with consideration for the resolution of tool movement at the stages of transition processes to assess the dynamical stability of a system in the process of manufacturing stepped surfaces of parts of “solid of revolution” type.

  2. Thermal/thermomechanical analyses for the room region with horizontal and vertial modes of emplacement

    International Nuclear Information System (INIS)

    1988-01-01

    Extensive thermal/thermomechanical analyses of the Site Characterization Plan-Conceptual Design at the Deaf Smith county Site, Texas, have been carried out for the room region with horizontal and vertical modes of emplacement. The main purpose of this study is to make a good comparison between these two modes of emplacement in this region. Homogeneous and nonhomogeneous strata under isothermal or transient temperature conditions cases were considered in the analyses. Furthermore, various pillar widths for the vertical mode emplacement were also taken into consideration. Only spent fuel (SF) waste was considered in this study. Finite element method was used throughout the analyses. The thermal responses were evaluated using SPECTROM-41 while the thermomechanical responses were calculated using SPECTROM-32. Thermal and thermomechanical comparisons between the two modes of emplacement for various cases were presented in this paper

  3. Design and verification of thermomechanical parameters of P/M Ti6Al4V alloy forging

    Energy Technology Data Exchange (ETDEWEB)

    Wojtaszek, Marek, E-mail: mwojtasz@metal.agh.edu.pl; Śleboda, Tomasz

    2014-12-05

    Highlights: • Thermomechanical parameters of P/M Ti6Al4V alloy processing were determined. • The use of the mixture of elemental powders allows reducing manufacturing costs. • Numerical modelling allowed to elaborate favourable parameters of forging. • The industrial trials of hot forging of P/M Ti6Al4V alloy were successful. - Abstract: This work is focused on the design of technology of forging high-quality Ti6Al4V alloy by means of powder metallurgy methods. A mixture of elemental powders, with the chemical composition of that of Ti6Al4V alloy, was used as a starting material for the investigation. Powder mixtures were fully densified by hot compaction under precisely controlled conditions. The mechanical properties of the obtained compacts were examined. The mechanical behaviour of the investigated alloy powder compacts was evaluated by compression test under various thermomechanical conditions using Gleeble simulator. The microstructure of powder compacts as well as P/M alloy samples deformed in compression tests was examined. All data obtained from the experimental tests were applied as boundary conditions for numerical simulation of forging of selected forgings. Basing on the results of both plastometric tests and simulations, thermomechanical parameters of the investigated alloy forging were determined. Designed parameters of forging technology were verified by forging trials performed in industrial conditions. The quality of the obtained forgings was examined by means of computed tomography.

  4. Design and verification of thermomechanical parameters of P/M Ti6Al4V alloy forging

    International Nuclear Information System (INIS)

    Wojtaszek, Marek; Śleboda, Tomasz

    2014-01-01

    Highlights: • Thermomechanical parameters of P/M Ti6Al4V alloy processing were determined. • The use of the mixture of elemental powders allows reducing manufacturing costs. • Numerical modelling allowed to elaborate favourable parameters of forging. • The industrial trials of hot forging of P/M Ti6Al4V alloy were successful. - Abstract: This work is focused on the design of technology of forging high-quality Ti6Al4V alloy by means of powder metallurgy methods. A mixture of elemental powders, with the chemical composition of that of Ti6Al4V alloy, was used as a starting material for the investigation. Powder mixtures were fully densified by hot compaction under precisely controlled conditions. The mechanical properties of the obtained compacts were examined. The mechanical behaviour of the investigated alloy powder compacts was evaluated by compression test under various thermomechanical conditions using Gleeble simulator. The microstructure of powder compacts as well as P/M alloy samples deformed in compression tests was examined. All data obtained from the experimental tests were applied as boundary conditions for numerical simulation of forging of selected forgings. Basing on the results of both plastometric tests and simulations, thermomechanical parameters of the investigated alloy forging were determined. Designed parameters of forging technology were verified by forging trials performed in industrial conditions. The quality of the obtained forgings was examined by means of computed tomography

  5. Step out - Step in Sequencing Games

    NARCIS (Netherlands)

    Musegaas, M.; Borm, P.E.M.; Quant, M.

    2014-01-01

    In this paper a new class of relaxed sequencing games is introduced: the class of Step out - Step in sequencing games. In this relaxation any player within a coalition is allowed to step out from his position in the processing order and to step in at any position later in the processing order.

  6. Netherlands : An ‘Echternach’ Procession in Different Directions: Oscillating Steps Towards Reform

    NARCIS (Netherlands)

    Westerheijden, Donald F.; de Boer, Harry F.; Enders, Jürgen; Paradeise, C.; Reale, E.; Bleiklie, I.; Ferlie, E.

    2009-01-01

    The annual procession in the Luxemburg town of Echternach is famous for its laborious manner of reaching its end: two steps forward, one step back. In this paper, we will maintain that the policy of the Dutch government over the period of c.1982–2007 resembles an Echternach procession in reverse:

  7. Two-step flash light sintering process for crack-free inkjet-printed Ag films

    International Nuclear Information System (INIS)

    Park, Sung-Hyeon; Kim, Hak-Sung; Jang, Shin; Lee, Dong-Jun; Oh, Jehoon

    2013-01-01

    In this paper, a two-step flash light sintering process for inkjet-printed Ag films is investigated with the aim of improving the quality of sintered Ag films. The flash light sintering process is divided into two steps: a preheating step and a main sintering step. The preheating step is used to remove the organic binder without abrupt vaporization. The main sintering step is used to complete the necking connections among the silver nanoparticles and achieve high electrical conductivity. The process minimizes the damage on the polymer substrate and the interface between the sintered Ag film and polymer substrate. The electrical conductivity is calculated by measuring the resistance and cross-sectional area with an LCR meter and 3D optical profiler, respectively. It is found that the resistivity of the optimal flash light-sintered Ag films (36.32 nΩ m), which is 228.86% of that of bulk silver, is lower than that of thermally sintered ones (40.84 nΩ m). Additionally, the polyimide film used as the substrate is preserved with the inkjet-printed pattern shape during the flash light sintering process without delamination or defects. (paper)

  8. Thermal and thermo-mechanical simulation of laser assisted machining

    International Nuclear Information System (INIS)

    Germain, G.; Dal Santo, P.; Lebrun, J. L.; Bellett, D.; Robert, P.

    2007-01-01

    Laser Assisted Machining (LAM) improves the machinability of materials by locally heating the workpiece just prior to cutting. The heat input is provided by a high power laser focused several millimeters in front of the cutting tool. Experimental investigations have confirmed that the cutting force can be decreased, by as much as 40%, for various materials (tool steel, titanium alloys and nickel alloys). The laser heat input is essentially superficial and results in non-uniform temperature profiles within the depth of the workpiece. The temperature field in the cutting zone is therefore influenced by many parameters. In order to understand the effect of the laser on chip formation and on the temperature fields in the different deformation zones, thermo-mechanical simulation were undertaken. A thermo-mechanical model for chip formation with and without the laser was also undertaken for different cutting parameters. Experimental tests for the orthogonal cutting of 42CrMo4 steel were used to validate the simulation via the prediction of the cutting force with and without the laser. The thermo-mechanical model then allowed us to highlight the differences in the temperature fields in the cutting zone with and without the laser. In particular, it was shown that for LAM the auto-heating of the material in the primary shear zone is less important and that the friction between the tool and chip also generates less heat. The temperature fields allow us to explain the reduction in the cutting force and the resulting residual stress fields in the workpiece

  9. Step out-step in sequencing games

    NARCIS (Netherlands)

    Musegaas, Marieke; Borm, Peter; Quant, Marieke

    2015-01-01

    In this paper a new class of relaxed sequencing games is introduced: the class of Step out–Step in sequencing games. In this relaxation any player within a coalition is allowed to step out from his position in the processing order and to step in at any position later in the processing order. First,

  10. Proceedings of the first thermomechanical workshop for shale

    International Nuclear Information System (INIS)

    1986-03-01

    Chapter 2 provides a description of the three federal regulations that pertain to the development of a high-level nuclear waste repository regardless of the rock type. Chapter 3 summarizes the reference shale repository conditions selected for this workshop. A room-and-pillar configuration was considered at an extraction ratio of about 0.25. The depth was assumed to be 700 m. Chapter 4 gives a summary of several case histories that were considered to be valuable in gaining an understanding of some of the design and construction features that might be unique in creating underground openings in shale. Chapter 5 assesses the data and information needs, availability, technology for acquisition, and the research and development necessary for analytical/numerical modeling in heat transfer, fluid flow, and thermomechanics. Chapter 6 assesses data and information needs in the laboratory and considerations associated with shale rock characterization. Chapter 7 assesses the data and information needs, availability, technology for acquisition, and the research and development necessary for field/in situ testing. Chapter 8 presents the consensus of the workshop participants that there is a definite need to advance the state of knowledge concerning the thermomechanical behavior of shales and to gain experience in applying this knowledge to the design of room-and-pillar excavations. Finally, Chapter 9 provides a summary of the research and development needs in the various interacting activities of repository development, including analytical/numerical modeling, laboratory testing, and field/in situ testing. The main conclusion of the workshop was that a need exists for an aggressive program in laboratory, field, numerical modeling, and design studies to provide a thermomechanical, technological base for comparison of shale types and shale regions/areas/sites

  11. Microstructure Refinement and Mechanical Properties of 304 Stainless Steel by Repetitive Thermomechanical Processing

    Science.gov (United States)

    Al-Fadhalah, Khaled; Aleem, Muhammad

    2018-04-01

    Repetitive thermomechanical processing (TMP) was applied for evaluating the effect of strain-induced α'-martensite transformation and reversion annealing on microstructure refinement and mechanical properties of 304 austenitic stainless steel. The first TMP scheme consisted of four cycles of tensile deformation to strain of 0.4, while the second TMP scheme applied two cycles of tensile straining to 0.6. For both schemes, tensile tests were conducted at 173 K (- 100 °C) followed by 5-minute annealing at 1073 K (800 °C). The volume fraction of α'-martensite in deformed samples increased with increasing cycles, reaching a maximum of 98 vol pct. Examination of annealed microstructure by electron backscattered diffraction indicated that increasing strain and/or number of cycles resulted in stronger reversion to austenite with finer grain size of 1 μm. Yet, increasing strain reduced the formation of Σ3 boundaries. The annealing textures generally show reversion of α'-martensite texture components to the austenite texture of brass and copper orientations. The increase in strain and/or number of cycles resulted in stronger intensity of copper orientation, accompanied by the formation of recrystallization texture components of Goss, cube, and rotated cube. The reduction in grain size with increasing cycles caused an increase in yield strength. It also resulted in an increase in strain hardening rate during deformation due to the increase in the formation of α'-martensite. The increase in strain hardening rate occurred in two consecutive stages, marked as stages II and III. The strain hardening in stage II is due to the formation of α'-martensite from either austenite or ɛ-martensite, while the stage-III strain hardening is attributed to the necessity to break the α'-martensite-banded structure for forming block-type martensite at high strains.

  12. Process Simulation of Aluminium Sheet Metal Deep Drawing at Elevated Temperatures

    International Nuclear Information System (INIS)

    Winklhofer, Johannes; Trattnig, Gernot; Lind, Christoph; Sommitsch, Christof; Feuerhuber, Hannes

    2010-01-01

    Lightweight design is essential for an economic and environmentally friendly vehicle. Aluminium sheet metal is well known for its ability to improve the strength to weight ratio of lightweight structures. One disadvantage of aluminium is that it is less formable than steel. Therefore complex part geometries can only be realized by expensive multi-step production processes. One method for overcoming this disadvantage is deep drawing at elevated temperatures. In this way the formability of aluminium sheet metal can be improved significantly, and the number of necessary production steps can thereby be reduced. This paper introduces deep drawing of aluminium sheet metal at elevated temperatures, a corresponding simulation method, a characteristic process and its optimization. The temperature and strain rate dependent material properties of a 5xxx series alloy and their modelling are discussed. A three dimensional thermomechanically coupled finite element deep drawing simulation model and its validation are presented. Based on the validated simulation model an optimised process strategy regarding formability, time and cost is introduced.

  13. The equations of the thermomechanics of electrically conducting nonferromagnetic bodies taking account of structural transformations

    International Nuclear Information System (INIS)

    Nagirnyi, T.S.

    1993-01-01

    Studies of the coupled processes in electrically conducting nonferromagnetic viscoelastic bodies usually begin with a system of equations that accounts for the influence of rheology on the mechanical and temperature fields. In this context, rheology is understood as the course of certain internal processes in the body that are reflected when the relaxation time and the defects of thermomechanical moduli are specified. In this work, the methods of continuum mechanics are used to state a system of equations for the quantitative description of coupled mechanical, thermal, and electromagnetic processes taking account of structural transformations in the context of the model of a rheologically simple electrically conducting nonferromagnetic body

  14. Thermo-mechanical design of the Plasma Driver Plate for the MITICA ion source

    Energy Technology Data Exchange (ETDEWEB)

    Pavei, Mauro, E-mail: mauro.pavei@igi.cnr.it [Consorzio RFX, EURATOM-ENEA Association, Corso Stati Uniti 4, I-35127 Padova (Italy); Palma, Mauro Dalla; Marcuzzi, Diego [Consorzio RFX, EURATOM-ENEA Association, Corso Stati Uniti 4, I-35127 Padova (Italy)

    2010-12-15

    In the framework of the activities for the development of the Neutral Beam Injector (NBI) for ITER, the detailed design of the Radio-Frequency (RF) negative ion source has been carried out. One of the most heated components of the RF source is the rear vertical plate, named Plasma Driver Plate (PDP), where the Back-Streaming positive Ions (BSI+) generated from stripping losses in the accelerator and back scattered on the plasma source impinge on. The heat loads that result are huge and concentrated, with first estimate of the power densities up to 60 MW/m{sup 2}. The breakdowns that occur into the accelerator cause such heat loads to act cyclically, so that the PDP is thermo-mechanically fatigue loaded. Moreover, the surface of the PDP facing the plasma is functionally required to be temperature controlled and to be molybdenum or tungsten coated. The thermo-hydraulic design of the plate has been carried out considering active cooling with ultra-pure water. Different heat sink materials, hydraulic circuit layout and manufacturing processes have been considered. The heat exhaust has been optimized by changing the channels geometry, the path of the heat flux in the heat sink, the thickness of the plate and maximizing the Heat Transfer Coefficient. Such optimization has been carried out by utilizing 3D Finite Element (FE) models. Afterwards all the suitable mechanical (aging, structural monotonic and cyclic) verifications have been carried out post-processing the results of the thermo-mechanical 3D FE analyses in accordance to specific procedures for nuclear components exposed to high temperature. The effect of sputtering phenomenon due to the high energy BSI+ impinging on the plate has been considered and combined with fatigue damage for the mechanical verification of the PDP. Alternative solutions having molybdenum (or tungsten coatings) facing the plasma, aiming to reduce the sputtering rate and the consequent plasma pollution, have been evaluated and related 3D FE

  15. Multi-step process for concentrating magnetic particles in waste sludges

    Science.gov (United States)

    Watson, John L.

    1990-01-01

    This invention involves a multi-step, multi-force process for dewatering sludges which have high concentrations of magnetic particles, such as waste sludges generated during steelmaking. This series of processing steps involves (1) mixing a chemical flocculating agent with the sludge; (2) allowing the particles to aggregate under non-turbulent conditions; (3) subjecting the mixture to a magnetic field which will pull the magnetic aggregates in a selected direction, causing them to form a compacted sludge; (4) preferably, decanting the clarified liquid from the compacted sludge; and (5) using filtration to convert the compacted sludge into a cake having a very high solids content. Steps 2 and 3 should be performed simultaneously. This reduces the treatment time and increases the extent of flocculation and the effectiveness of the process. As partially formed aggregates with active flocculating groups are pulled through the mixture by the magnetic field, they will contact other particles and form larger aggregates. This process can increase the solids concentration of steelmaking sludges in an efficient and economic manner, thereby accomplishing either of two goals: (a) it can convert hazardous wastes into economic resources for recycling as furnace feed material, or (b) it can dramatically reduce the volume of waste material which must be disposed.

  16. Thermomechanical treatment of austempered ductile iron

    Directory of Open Access Journals (Sweden)

    A. A. Nofal

    2007-11-01

    Full Text Available The production of lightweight ferrous castings with increased strength properties became unavoidable facing the serious challenge of lighter aluminum and magnesium castings. The relatively new ferrous casting alloy ADI offers promising strength prospects, and the thermo-mechanical treatment of ductile iron may suggest a new route for production of thin-wall products. This work aims at studying the influence of thermomechanical treatment, either by ausforming just after quenching and before the onset of austempering reaction or by cold rolling after austempering. In the first part of this work, ausforming of ADI up to 25% reduction in height during a rolling operation was found to add a mechanical processing component compared to the conventional ADI heat treatment, thus increasing the rate of ausferrite formation and leading to a much finer and more homogeneous ausferrite product. The kinetics of ausferrite formation was studied using both metallographic as well as XRD-techniques. The effect of ausforming on the strength was quite dramatic (up to 70% and 50% increase in the yield and ultimate strength respectively. A mechanism involving both a refined microstructural scale and an elevated dislocation density was suggested. Nickel is added to ADI to increase hardenability of thick section castings, while ausforming to higher degrees of deformation is necessary to alleviate the deleterious effect of alloy segregation on ductility. In the second part of this work, the influence of cold rolling (CR on the mechanical properties and structural characteristics of ADI was investigated. The variation in properties was related to the amount of retained austenite (γr and its mechanically induced ransformation. In the course of tensile deformation of ADI, transformation induced plasticity (TRIP takes place, indicated by the increase of the instantaneous value of strain-hardening exponent with tensile strain. The amount of retained austenite was found to

  17. 48 CFR 15.202 - Advisory multi-step process.

    Science.gov (United States)

    2010-10-01

    ... CONTRACTING METHODS AND CONTRACT TYPES CONTRACTING BY NEGOTIATION Solicitation and Receipt of Proposals and Information 15.202 Advisory multi-step process. (a) The agency may publish a presolicitation notice (see 5.204) that provides a general description of the scope or purpose of the acquisition and invites potential...

  18. Strategic planning: the first step in the planning process.

    Science.gov (United States)

    Gelinas, Marc A

    2003-01-01

    Strategic planning is a systematic process through which an organization builds commitment among key stakeholders to goals and priorities which are essential to its mission and vision, and responsive to the operating environment. Strategic planning is the first step in a comprehensive planning process that also includes business planning and implementation planning. If all three steps are carried out in sequence, strategic planning can be a very effective means of educating the stakeholders about where the cancer program is and where it is going, gaining support and commitment for the direction that the cancer program will take, and assuring that everyone's expectations can be managed effectively. Unfortunately, some organizations and cancer program leaders misunderstand the process. Too often, strategic planning is used as a stand-alone activity. This article will describe what strategic planning is, how it should smoothly lead into business planning and implementation planning, and how to avoid the pitfalls that sometimes arise during the strategic planning effort.

  19. The thermomechanical stability of micro-solid oxide fuel cells fabricated on anodized aluminum oxide membranes

    Science.gov (United States)

    Kwon, Chang-Woo; Lee, Jae-Il; Kim, Ki-Bum; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2012-07-01

    The thermomechanical stability of micro-solid oxide fuel cells (micro-SOFCs) fabricated on an anodized aluminum oxide (AAO) membrane template is investigated. The full structure consists of the following layers: AAO membrane (600 nm)/Pt anode/YSZ electrolyte (900 nm)/porous Pt cathode. The utilization of a 600-nm-thick AAO membrane significantly improves the thermomechanical stability due to its well-known honeycomb-shaped nanopore structure. Moreover, the Pt anode layer deposited in between the AAO membrane and the YSZ electrolyte preserves its integrity in terms of maintaining the triple-phase boundary (TPB) and electrical conductivity during high-temperature operation. Both of these results guarantee thermomechanical stability of the micro-SOFC and extend the cell lifetime, which is one of the most critical issues in the fabrication of freestanding membrane-type micro-SOFCs.

  20. ITER baffle module small-scale mock-ups: first wall thermo-mechanical testing results

    International Nuclear Information System (INIS)

    Severi, Y.; Giancarli, L.; Poitevin, Y.; Salavy, J.F.; Le Marois, G.; Roedig, M.; Vieider, G.

    1998-01-01

    The EU-home team is in charge of the R and D related to the ITER baffle first wall. Five small-scale mock-ups, using Be, CFC and W tiles and different armour/heat-sink material joints under development, have been fabricated and thermomechanically tested in FE200 (Le Creusot) and JUDITH (Juelich) electron beam facilities. The small-scale mock-ups have been submitted to thermo-mechanical fatigue tests (up to failure using accelerating techniques). The objective was to determine the performances of the armour material joints under high heat flux cycles. (orig.)

  1. Hydrogen embrittlement of thermomechanically treated 18Ni Maraging steel

    International Nuclear Information System (INIS)

    Munford, J.W.; Rack, H.J.; Kass, W.J.

    1977-01-01

    The influence of thermomechanical treatments on susceptibility to cracking in 100 percent relative humidity air and low pressure (93.3 KPa) gaseous hydrogen has been investigated for 18Ni (350 ksi) Maraging steel. Two thermomechanical treatments were studied, ausforming and marforming and compared with the standard solution treated and aged material. Although little difference exists for the strength and toughness values between these treatments, a two to five-fold increase in the stress intensity threshold for cracking was found for both the ausformed and marformed material. A dramatic difference in cracking kinetics was also apparent as shown by the failure times at comparable stress intensities. Fractographic analysis showed that the primary fracture mode was 100 percent intergranular for the solution treated and aged samples while the ausform and marform failures were predominately quasi-cleavage or intergranular depending on orientation. Finally, permeation and diffusion measurements were conducted on the above materials and these results are correlated with the environmental cracking behavior

  2. Hydrogen embrittlement of thermomechanically treated 18Ni Maraging steel

    Energy Technology Data Exchange (ETDEWEB)

    Munford, J.W.; Rack, H.J.; Kass, W.J.

    1977-01-01

    The influence of thermomechanical treatments on susceptibility to cracking in 100 percent relative humidity air and low pressure (93.3 KPa) gaseous hydrogen has been investigated for 18Ni (350 ksi) Maraging steel. Two thermomechanical treatments were studied, ausforming and marforming and compared with the standard solution treated and aged material. Although little difference exists for the strength and toughness values between these treatments, a two to five-fold increase in the stress intensity threshold for cracking was found for both the ausformed and marformed material. A dramatic difference in cracking kinetics was also apparent as shown by the failure times at comparable stress intensities. Fractographic analysis showed that the primary fracture mode was 100 percent intergranular for the solution treated and aged samples while the ausform and marform failures were predominately quasi-cleavage or intergranular depending on orientation. Finally, permeation and diffusion measurements were conducted on the above materials and these results are correlated with the environmental cracking behavior.

  3. ISOTHERMAL AND THERMOMECHANICAL FATIGUE OF A NICKEL-BASE SUPERALLOY

    Directory of Open Access Journals (Sweden)

    Carlos Carvalho Engler-Pinto Júnior

    2014-06-01

    Full Text Available Thermal gradients arising during transient regimes of start-up and shutdown operations produce a complex thermal and mechanical fatigue loading which limits the life of turbine blades and other engine components operating at high temperatures. More accurate and reliable assessment under non-isothermal fatigue becomes therefore mandatory. This paper investigates the nickel base superalloy CM 247LC-DS under isothermal low cycle fatigue (LCF and thermomechanical fatigue (TMF. Test temperatures range from 600°C to 1,000°C. The behavior of the alloy is strongly affected by the temperature variation, especially in the 800°C-1,000°C range. The Ramberg-Osgood equation fits very well the observed isothermal behavior for the whole temperature range. The simplified non-isothermal stress-strain model based on linear plasticity proposed to represent the thermo-mechanical fatigue behavior was able to reproduce the observed behavior for both in-phase and out-of-phase TMF cycling.

  4. Standard practice for strain controlled thermomechanical fatigue testing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers the determination of thermomechanical fatigue (TMF) properties of materials under uniaxially loaded strain-controlled conditions. A “thermomechanical” fatigue cycle is here defined as a condition where uniform temperature and strain fields over the specimen gage section are simultaneously varied and independently controlled. This practice is intended to address TMF testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. While this practice is specific to strain-controlled testing, many sections will provide useful information for force-controlled or stress-controlled TMF testing. 1.2 This practice allows for any maximum and minimum values of temperature and mechanical strain, and temperature-mechanical strain phasing, with the restriction being that such parameters remain cyclically constant throughout the duration of the test. No restrictions are placed on en...

  5. Mechanical and thermomechanical properties of polycarbonate-based polyurethane-silica nanocomposites

    Directory of Open Access Journals (Sweden)

    Rafał Poręba

    2011-09-01

    Full Text Available In this work aliphatic polycarbonate-based polyurethane-silica nanocomposites were synthesized and characterized. The influence of the type and of the concentration of nanofiller differing in average particle size (7 nm for Aerosil 380 and 40 nm for Nanosilica 999 on mechanical and thermomechanical properties was investigated. DMTA measurements showed that Nanosilica 999, irrespective of its concentration, slightly increased the value of the storage shear modulus G’ but Aerosil 380 brings about a nearly opposite effect, the shear modulus in the rubber region decreases with increasing filler content. Very high elongations at break ranging from 800% to more than 1000%, as well as high tensile strengths illustrate excellent ultimate tensile properties of the prepared samples. The best mechanical and thermomechanical properties were found for the sample filled with 0.5 wt.% of Nanosilica 999.

  6. Damage evolution of TBC system under in-phase thermo-mechanical tests

    International Nuclear Information System (INIS)

    Kitazawa, R.; Tanaka, M.; Kagawa, Y.; Liu, Y.F.

    2010-01-01

    In-phase thermo-mechanical tests (TMF) of EB-PVD Y 2 O 3 -ZrO 2 thermal barrier coating (TBC) system (8 wt% Y 2 O 3 -ZrO 2 /CoNiCrAlY/IN-738 substrate) were done under a through-the-thick-direction thermal gradient from TBC surface temperature at 1150 deg. C to substrate temperature at 1000 deg. C. Deformation and failure behaviors of the TBC system were observed at the macroscopic and microscopic scales and damage evolution of the system under in-phase thermo-mechanical test was discussed. Special attention was paid to TBC layer cracking, thermally grown oxide (TGO) layer formation and void formation in bond coat and substrate. Effect of TMF conditions on the damage evolution behaviors was also discussed.

  7. Ultralow-density SiO2 aerogels prepared by a two-step sol-gel process

    International Nuclear Information System (INIS)

    Wang Jue; Li Qing; Shen Jun; Zhou Bin; Chen Lingyan; Jiang; Weiyang

    1996-01-01

    Low density SiO 2 gels are prepared by a two-step sol-gel process from TEOS. The influence of various solution ratios on the gelation process is investigated. The comparative characterization of gels using different solvent, such as ethanol, acetone and methyl cyanide, is also given. The ultralow-density SiO 2 aerogels with density less than 10 kg/m 3 are prepared by CO 2 supercritical drying technique. The structure difference between SiO 2 aerogels prepared by conventional single-step process and the two-step process is also presented

  8. Application of a new thermo-mechanical model for the study of the nuclear waste disposal in clay rocks

    International Nuclear Information System (INIS)

    Dizier, A.; Li, X.L.; Francois, B.; Collin, F.; Charlier, R.

    2012-01-01

    (LY curve (Loading Yield)). This one may be considered analogous with the LC curve (Loading Collapse) met in the Barcelona Basic Model dedicated to unsaturated soil mechanics. This thermo-mechanical law has been used to model the PRACLAY experiment and particularly to analyse the evolution of the damaged zone with temperature. In this study, the damaged zone is considered as the sum of two plastic strain components, a deviatoric and a volumetric one. The deviatoric strains are induced when the internal friction criterion is reached while the volumetric strains are a consequence of the Cam - Clay model or the TY curve. The results of the evolution of the deviatoric strain show that the magnitude of this strain is modified near the wall but the extension of the size of the plastic deviatoric zone is not affected by temperature. The modification of the deviatoric strain near the wall can be explained by hydro-mechanical coupling caused by thermally induced excess pore water pressure which permits the stress path to reach the internal friction criterion. Concerning the volumetric plastic strains, these follow the effect of the thermal load and the size of the zone affected by these strains correspond to the zone affected by the temperature. On the contrary the magnitude of the strain depends on the state of stress of the clay as observed near the wall. Indeed, the stresses near the wall are reduced due to the process of excavation and the state of stress exhibits a kind of over-consolidation effect where only thermal dilation is possible. In that modelling, the set of parameters chosen doesn't allow the activation of the LY curve. Finally the results obtained with this new thermo-mechanical law have been compared with results obtained with other thermo-mechanical law, that is to say with ACMEG-T which is a thermo-plastic law developed at EPFL and a classical thermo-elastic law. The comparison shows that the results obtained with the two thermo-plastic constitutive laws

  9. Modelling of the thermomechanical behaviour of salt rock

    International Nuclear Information System (INIS)

    Albers, G.; Graefe, V.; Korthaus, E.; Pudewillis, A.; Prij, J.

    1986-01-01

    The modelling of the thermomechanical behaviour of salt rock is examined, with respect to the disposal of radioactive waste in salt formations. The calculation methods and programmes currently available for the modelling are described. Some examples are given of calculations carried out in parallel with tests. Some results of modelling calculations for a repository are presented by way of illustration. (U.K.)

  10. Simulation of Unique Pressure Changing Steps and Situations in Psa Processes

    Science.gov (United States)

    Ebner, Armin D.; Mehrotra, Amal; Knox, James C.; LeVan, Douglas; Ritter, James A.

    2007-01-01

    A more rigorous cyclic adsorption process simulator is being developed for use in the development and understanding of new and existing PSA processes. Unique features of this new version of the simulator that Ritter and co-workers have been developing for the past decade or so include: multiple absorbent layers in each bed, pressure drop in the column, valves for entering and exiting flows and predicting real-time pressurization and depressurization rates, ability to account for choked flow conditions, ability to pressurize and depressurize simultaneously from both ends of the columns, ability to equalize between multiple pairs of columns, ability to equalize simultaneously from both ends of pairs of columns, and ability to handle very large pressure ratios and hence velocities associated with deep vacuum systems. These changes to the simulator now provide for unique opportunities to study the effects of novel pressure changing steps and extreme process conditions on the performance of virtually any commercial or developmental PSA process. This presentation will provide an overview of the cyclic adsorption process simulator equations and algorithms used in the new adaptation. It will focus primarily on the novel pressure changing steps and their effects on the performance of a PSA system that epitomizes the extremes of PSA process design and operation. This PSA process is a sorbent-based atmosphere revitalization (SBAR) system that NASA is developing for new manned exploration vehicles. This SBAR system consists of a 2-bed 3-step 3-layer system that operates between atmospheric pressure and the vacuum of space, evacuates from both ends of the column simultaneously, experiences choked flow conditions during pressure changing steps, and experiences a continuously changing feed composition, as it removes metabolic CO2 and H20 from a closed and fixed volume, i.e., the spacecraft cabin. Important process performance indicators of this SBAR system are size, and the

  11. Development of low enriched uranium target plates by thermo-mechanical processing of UAl{sub 2}–Al matrix for production of {sup 99}Mo in Pakistan

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Kanwar Liaqat; Khan, Akhlaque Ahmad [Pakistan Institute of Nuclear Science and Technology (PINSTECH) P.O Nilore, Islamabad (Pakistan); Mushtaq, Ahmad, E-mail: amushtaq1@hotmail.com [Pakistan Institute of Nuclear Science and Technology (PINSTECH) P.O Nilore, Islamabad (Pakistan); Imtiaz, Farhan; Ziai, Maratab Ali; Gulzar, Amir; Farooq, Muhammad; Hussain, Nazar; Ahmed, Nisar; Pervez, Shahid; Zaidi, Jamshed Hussain [Pakistan Institute of Nuclear Science and Technology (PINSTECH) P.O Nilore, Islamabad (Pakistan)

    2013-02-15

    Uranium aluminide predominated with UAl{sub 2} phase was prepared by arc-melting procedures and comminuted to required particle size. UAl{sub 2} and Al powders were blended and compacted to achieve LEU fuel density of 2.17 g/cm{sup 3}. The picture-frame technique was used to clad the dispersions (UAl{sub 2}–Al) with aluminum. A few target plates were fabricated by thermo-mechanical processing (hot rolling and annealing) of UAl{sub 2}–Al matrix contained in roll billet of Al. The fabricated plates were characterized by destructive and some of non-destructive testing techniques and then annealed to achieve required phase of uranium aluminide for proper dissolution in basic media.

  12. Uncertainty analysis of a one-dimensional constitutive model for shape memory alloy thermomechanical description

    DEFF Research Database (Denmark)

    Oliveira, Sergio A.; Savi, Marcelo A.; Santos, Ilmar F.

    2014-01-01

    The use of shape memory alloys (SMAs) in engineering applications has increased the interest of the accuracy analysis of their thermomechanical description. This work presents an uncertainty analysis related to experimental tensile tests conducted with shape memory alloy wires. Experimental data...... are compared with numerical simulations obtained from a constitutive model with internal constraints employed to describe the thermomechanical behavior of SMAs. The idea is to evaluate if the numerical simulations are within the uncertainty range of the experimental data. Parametric analysis is also developed...

  13. Role of grain refinement in hardening of structural steels at preliminary thermomechanical treatment

    International Nuclear Information System (INIS)

    Bukhvalov, A.B.; Grigor'eva, E.V.; Davydova, L.S.; Degtyarev, M.V.; Levit, V.I.; Smirnova, N.A.; Smirnov, L.V.

    1981-01-01

    The hardening mechanism during preliminary thermomechanical treatment with deformation by cold rolling or hydroextrusion is studied on structural 37KhN3M1 and 38KhN3MFA steels. Specimens have been tested on static tension, impact strength and fracture toughness. It is shown that hydroextrusion application instead of rolling does not change the hardening effect of preliminary thermomechanical treatment (PTMT). It is established that the increase of preliminary deformation degree and the use of accelerated short term hardening heating provides a bett er grain refinement and the increase of PTMT hardening effect [ru

  14. Cyclic life of superalloy IN738LC under in-phase and out-of-phase thermo-mechanical fatigue loading

    International Nuclear Information System (INIS)

    Chen Hongjun; Wahi, R.P.; Wever, H.

    1995-01-01

    The cyclic life of IN738LC, a widely used nickel base superalloy for blades in stationary gas turbines, was investigated under thermo-mechanical fatigue loading using a temperature variation range of 1023 to 1223 K, with temperature variation rate in the range of 6 to 15 K/min. Simple thermo-mechanical cycles with linear sequences corresponding to in-phase (IP) and out-of-phase (OP) tests were performed. Both the IP and OP tests were carried out at different constant mechanical strain ranges varied between 0.8 to 2.0% and at a constant mechanical strain rate of 10 -5 s -1 . Thermo-mechanical fatigue lives under both test conditions were compared with each other and with those of isothermal LCF tests at a temperature of 1223 K. The results show that the life under thermo-mechanical fatigue is strongly dependent on the nature of the test, i.e. stress controlled or strain controlled. (orig.)

  15. 42 CFR 50.406 - What are the steps in the process?

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false What are the steps in the process? 50.406 Section 50.406 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS POLICIES OF GENERAL APPLICABILITY Public Health Service Grant Appeals Procedure § 50.406 What are the steps in...

  16. Near-field thermal transient and thermomechanical stress analysis of a disposal vault in crystalline hard rock

    International Nuclear Information System (INIS)

    Tsui, K.K.; Tsai, A.; Lee, C.F.

    1981-01-01

    The Canadian Nuclear Fuel Waste Management Program currently focuses on the development of a disposal vault in crystalline hard rock at a reference depth of 1 km below the surface in a suitable pluton in the Canadian Shield. As part of Ontario Hydro's technical assistance to the Atomic Energy of Canada Limited in this program, studies are being carried out to determine the effects of radiogenic heat on the near-field behaviour of a disposal vault. This paper presents the study results obtained to date. Temperature and stress fields were computed and cross-checked by several finite element codes. A comparison between vertical and horizontal borehole emplacement concepts is made. The effects of material non-linearity (temperature dependence) and three-dimensionality on the thermomechanical response are evaluated. Case histories of thermal spalling or fracturing in rock were summarized and discussed to illustrate the possible mechanisms and processes involved in thermal fracturing. An assessment of the thermomechanical stability of the rock mass around a disposal vault under a state of high horizontal in-situ stress is also presented

  17. Transformation-induced plasticity in multiphase steels subjected to thermomechanical loading

    NARCIS (Netherlands)

    Tjahjanto, D.D.; Turteltaub, S.R.; Suiker, A.S.J.; Zwaag, van der S.

    2008-01-01

    The behaviour of transformation-induced plasticity steels subjected to combined thermomechanical loading is studied at the microscale by means of numerical simulations. The microstructure is composed of an austenitic phase that may deform plastically and/or transform into martensite, and a ferritic

  18. Thermomechanical Morphology of Peas and Its Relation to Fracture Behaviour

    NARCIS (Netherlands)

    Pelgrom, P.J.M.; Schutyser, M.A.I.; Boom, R.M.

    2013-01-01

    Milling and subsequent air classification can be exploited for production of functional protein-enriched fractions from legumes and grains. Fracture behaviour is of large relevance to optimal disentanglement of protein and starch and is determined by the thermomechanical morphology of the seeds.

  19. Thermophysical and Thermomechanical Properties of Thermal Barrier Coating Systems

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2000-01-01

    Thermal barrier coatings have been developed for advanced gas turbine and diesel engine applications to improve engine reliability and fuel efficiency. However, the issue of coating durability under high temperature cyclic conditions is still of major concern. The coating failure is closely related to thermal stresses and oxidation in the coating systems. Coating shrinkage cracking resulting from ceramic sintering and creep at high temperatures can further accelerate the coating failure process. The purpose of this paper is to address critical issues such as ceramic sintering and creep, thermal fatigue and their relevance to coating life prediction. Novel test approaches have been established to obtain critical thermophysical and thermomechanical properties of the coating systems under near-realistic temperature and stress gradients encountered in advanced engine systems. Emphasis is placed on the dynamic changes of the coating thermal conductivity and elastic modulus, fatigue and creep interactions, and resulting failure mechanisms during the simulated engine tests. Detailed experimental and modeling results describing processes occurring in the thermal barrier coating systems provide a framework for developing strategies to manage ceramic coating architecture, microstructure and properties.

  20. Fracture mechanics in new designed power module under thermo-mechanical loads

    Directory of Open Access Journals (Sweden)

    Durand Camille

    2014-06-01

    Full Text Available Thermo-mechanically induced failure is a major reliability issue in the microelectronic industry. On this account, a new type of Assembly Interconnected Technology used to connect MOSFETs in power modules has been developed. The reliability is increased by using a copper clip soldered on the top side of the chip, avoiding the use of aluminium wire bonds, often responsible for the failure of the device. Thus the new designed MOSFET package does not follow the same failure mechanisms as standard modules. Thermal and power cycling tests were performed on these new packages and resulting failures were analyzed. Thermo-mechanical simulations including cracks in the aluminium metallization and intermetallics (IMC were performed using Finite Element Analysis in order to better understand crack propagation and module behaviour.

  1. Damage evolution of TBC system under in-phase thermo-mechanical tests

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, R.; Tanaka, M.; Kagawa, Y. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Liu, Y.F., E-mail: yfliu@hyper.rcast.u-tokyo.ac.jp [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan)

    2010-10-15

    In-phase thermo-mechanical tests (TMF) of EB-PVD Y{sub 2}O{sub 3}-ZrO{sub 2} thermal barrier coating (TBC) system (8 wt% Y{sub 2}O{sub 3}-ZrO{sub 2}/CoNiCrAlY/IN-738 substrate) were done under a through-the-thick-direction thermal gradient from TBC surface temperature at 1150 deg. C to substrate temperature at 1000 deg. C. Deformation and failure behaviors of the TBC system were observed at the macroscopic and microscopic scales and damage evolution of the system under in-phase thermo-mechanical test was discussed. Special attention was paid to TBC layer cracking, thermally grown oxide (TGO) layer formation and void formation in bond coat and substrate. Effect of TMF conditions on the damage evolution behaviors was also discussed.

  2. HETC-3STEP included fragmentation process

    Energy Technology Data Exchange (ETDEWEB)

    Shigyo, Nobuhiro; Iga, Kiminori; Ishibashi, Kenji [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering

    1997-03-01

    High Energy Transport Code (HETC) based on the cascade-evaporation model is modified to calculate the fragmentation cross section. For the cascade process, nucleon-nucleon cross sections are used for collision computation; effective in-medium-corrected cross sections are adopted instead of the original free-nucleon collision. The exciton model is adopted for improvement of backward nucleon-emission cross section for low-energy nucleon-incident events. The fragmentation reaction is incorporated into the original HETC as a subroutine set by the use of the systematics of the reaction. The modified HETC (HETC-3STEP/FRG) reproduces experimental fragment yields to a reasonable degree. (author)

  3. Regional-scale geomechanical impact assessment of underground coal gasification by coupled 3D thermo-mechanical modeling

    Science.gov (United States)

    Otto, Christopher; Kempka, Thomas; Kapusta, Krzysztof; Stańczyk, Krzysztof

    2016-04-01

    Underground coal gasification (UCG) has the potential to increase the world-wide coal reserves by utilization of coal deposits not mineable by conventional methods. The UCG process involves combusting coal in situ to produce a high-calorific synthesis gas, which can be applied for electricity generation or chemical feedstock production. Apart from its high economic potentials, UCG may induce site-specific environmental impacts such as fault reactivation, induced seismicity and ground subsidence, potentially inducing groundwater pollution. Changes overburden hydraulic conductivity resulting from thermo-mechanical effects may introduce migration pathways for UCG contaminants. Due to the financial efforts associated with UCG field trials, numerical modeling has been an important methodology to study coupled processes considering UCG performance. Almost all previous UCG studies applied 1D or 2D models for that purpose, that do not allow to predict the performance of a commercial-scale UCG operation. Considering our previous findings, demonstrating that far-field models can be run at a higher computational efficiency by using temperature-independent thermo-mechanical parameters, representative coupled simulations based on complex 3D regional-scale models were employed in the present study. For that purpose, a coupled thermo-mechanical 3D model has been developed to investigate the environmental impacts of UCG based on a regional-scale of the Polish Wieczorek mine located in the Upper Silesian Coal Basin. The model size is 10 km × 10 km × 5 km with ten dipping lithological layers, a double fault and 25 UCG reactors. Six different numerical simulation scenarios were investigated, considering the transpressive stress regime present in that part of the Upper Silesian Coal Basin. Our simulation results demonstrate that the minimum distance between the UCG reactors is about the six-fold of the coal seam thickness to avoid hydraulic communication between the single UCG

  4. First-principles study of thermal expansion and thermomechanics of single-layer black and blue phosphorus

    International Nuclear Information System (INIS)

    Sun, Hongyi; Liu, Gang; Li, Qingfang; Wan, X.G.

    2016-01-01

    The linear thermal expansion coefficients (LTEC) and thermomechanics of single-layer black and blue phosphorus are systematically studied using first-principles based on quasiharmonic approximation. We find the thermal expansion of black phosphorus is very anisotropic. The LTEC along zigzag direction has a turning from negative to positive at around 138 K, while the LTEC along armchair direction is positive (except below 8 K) and about 2.5 times larger than that along zigzag direction at 300 K. For blue phosphorus, the LTEC is negative in the temperature range from 0 to 350 K. In addition, we find that the Young's modulus and Poisson's ratio of black phosphorus along zigzag direction are 4 to 5 times larger than those along armchair direction within considered temperature range, showing a remarkable anisotropic in-plane thermomechanics property. The mechanisms of these peculiar thermal properties are also explored. This work provides a theoretical understanding of the thermal expansion and thermomechanics of this single layer phosphorus family, which will be useful in nanodevices. - Highlights: • The thermal properties of black and blue phosphorus are studied. • Black phosphorus shows remarkable anisotropic thermal expansion and thermomechanics properties. • Blue phosphorus shows novel negative thermal expansion. • The thermal expansion properties are well analyzed by grüneisen theory.

  5. Study of texture and microstructure evaluation of steel API 5L X70 under various thermomechanical cycles

    Energy Technology Data Exchange (ETDEWEB)

    Masoumi, Mohammad, E-mail: Mohammad@alu.ufc.br; Herculano, Luis Flavio Gaspar; Ferreira Gomes de Abreu, Hamilton

    2015-07-15

    This work studies the influence of different thermomechanical paths on the microstructure and crystallographic texture across the thickness of API 5L X70 pipeline steel manufactured via hot rolling using X-ray diffraction (XRD), scanning electron microscope (SEM), and electron backscattered diffraction (EBSD). The starting materials were controlled hot-rolled at 1000 °C to 44% and 67% reductions and subsequently heat treated with such processes as annealing, water quenching and quench tempering at three different temperatures to evaluate the microstructure and crystallographic texture changes across the thickness. The banded ferrite-pearlite microstructure of the initial material was changed to acicular ferrite, quasi-polygonal ferrite, granular bainite, martensite and retained austenite via different heat treatments. Moreover, different thermomechanical paths induced crystallographic texture variations across the thickness, e.g., {112}//ND, {111}//ND (γ fibre), and {011}//ND fibres dominated on the surface plane in contact with the rolls, whereas {001}//ND and particularly the (001)[1 1 0] texture component developed in the centre plane on which shear deformation has a zero value in this region. In this study, a simple interpretation of texture evolution was analyzed by comparison with the orientation changes that occurred during different rolling schedules and post-treatment processes.

  6. New three-dimensional far-field potential repository thermomechanical calculations

    International Nuclear Information System (INIS)

    Hardy, M.P.; Bai, M.; Goodrich, R.R.; Lin, M.; Carlisle, S.; Bauer, S.J.

    1993-03-01

    The thermomechanical effect on the exploratory ramps, drifts, and shafts as a result of high-level nuclear waste disposal is examined using a three-dimensional thermo-elastic model. The repository layout modeled is based on the use of mechanical mining of all excavations with equivalent waste emplacement areal power densities of 57 and 80 kW/acre. Predicted temperatures and stress changes for the north and south access drifts, east main drift, east-west exploratory drift, the north and south Calico Hills access ramps, the Calico Hills north-south exploratory drift, and the optional exploratory studies facility and man and materials shafts are presented for times 10, 35, 50, 100, 300, 500, 1000, 2000, 5000, and 10,000 years after the start of waste emplacement. The study indicates that the east-west exploratory drift at the repository horizon is subject to the highest thermomechanical impact because it is located closest the buried waste canisters. For most exploratory openings, the thermally induced temperatures and stresses tend to reach the maximum magnitudes at approximately 1000 years after waste emplacement

  7. Coupling of Spinosad Fermentation and Separation Process via Two-Step Macroporous Resin Adsorption Method.

    Science.gov (United States)

    Zhao, Fanglong; Zhang, Chuanbo; Yin, Jing; Shen, Yueqi; Lu, Wenyu

    2015-08-01

    In this paper, a two-step resin adsorption technology was investigated for spinosad production and separation as follows: the first step resin addition into the fermentor at early cultivation period to decrease the timely product concentration in the broth; the second step of resin addition was used after fermentation to adsorb and extract the spinosad. Based on this, a two-step macroporous resin adsorption-membrane separation process for spinosad fermentation, separation, and purification was established. Spinosad concentration in 5-L fermentor increased by 14.45 % after adding 50 g/L macroporous at the beginning of fermentation. The established two-step macroporous resin adsorption-membrane separation process got the 95.43 % purity and 87 % yield for spinosad, which were both higher than that of the conventional crystallization of spinosad from aqueous phase that were 93.23 and 79.15 % separately. The two-step macroporous resin adsorption method has not only carried out the coupling of spinosad fermentation and separation but also increased spinosad productivity. In addition, the two-step macroporous resin adsorption-membrane separation process performs better in spinosad yield and purity.

  8. Thermomechanical behaviour of boom clay

    International Nuclear Information System (INIS)

    Sultan, N.; Delage, P.; Cui, Y.J.

    2000-01-01

    Special attention has been recently paid on temperature effects on the behaviour of deep saturated clays, in relation with nuclear deep waste storage. However, few experimental data are presently available, and existing constitutive models need to be completed. This note is aimed at completing, both experimentally and theoretically, the understanding of the effects of the over-consolidation ration on the thermal volume changes of Boom clay (Belgium). The experimental data obtained here are in a good agreement with existing data. As a complement to existing data, they are used to develop a new elastoplastic model. The adoption of a second coupled plastic mechanism provides good simulations on a complex thermo-mechanical path. (authors)

  9. Photon Production through Multi-step Processes Important in Nuclear Fluorescence Experiments

    International Nuclear Information System (INIS)

    Hagmann, C; Pruet, J

    2006-01-01

    The authors present calculations describing the production of photons through multi-step processes occurring when a beam of gamma rays interacts with a macroscopic material. These processes involve the creation of energetic electrons through Compton scattering, photo-absorption and pair production, the subsequent scattering of these electrons, and the creation of energetic photons occurring as these electrons are slowed through Bremsstrahlung emission. Unlike single Compton collisions, during which an energetic photon that is scattered through a large angle loses most of its energy, these multi-step processes result in a sizable flux of energetic photons traveling at large angles relative to an incident photon beam. These multi-step processes are also a key background in experiments that measure nuclear resonance fluorescence by shining photons on a thin foil and observing the spectrum of back-scattered photons. Effective cross sections describing the production of backscattered photons are presented in a tabular form that allows simple estimates of backgrounds expected in a variety of experiments. Incident photons with energies between 0.5 MeV and 8 MeV are considered. These calculations of effective cross sections may be useful for those designing NRF experiments or systems that detect specific isotopes in well-shielded environments through observation of resonance fluorescence

  10. Thermo-mechanical behavior of retro-reflector and resulting parallelism error of laser beams for Wendelstein 7-X interferometer

    International Nuclear Information System (INIS)

    Peng, X.B.; Hirsch, M.; Köppen, M.; Fellinger, J.; Bykov, V.; Schauer, F.; Vliegenthart, W.

    2014-01-01

    Highlights: • The criterion for thermo-mechanical design of W7-X interferometer retro-reflector. • Thermo-mechanical analysis of retro-reflector with two different methods. • The most flexible part in the retro-reflector is spring washer. • Calculation of parallelism error between the incoming and reflected laser beams. • The parallelism error is much lower than the design limit 28 arcs. - Abstract: A 10 channels interferometer will be used in the Wendelstein 7-X (W7-X) for plasma density control and density profile tracking with laser beams passing through the plasma. Due to complex shape of non-planar modular coils and divertor structure, there are no large poloidally opposite ports on the plasma vessel (PV). Therefore 10 in-vessel Corner Cube Retro-reflectors (CCRs) will be used. The CCRs are integrated in the water cooled heat shield and exposed directly to thermal loads from plasma radiation. Thermo-mechanical issues are very important for the design of the CCR because deformation and flatness as well as mutual angles of the three reflecting surfaces would affect the parallelism of the laser beams and the functionality of the interferometer. Intensive work has been done to explore a suitable design for the CCR concerning thermo-mechanical behavior. Previous studies Ye et al. (2008, 2009) and Köppen et al. (2011) focused on structural optimization to decrease thermal stress in the reflecting plates under the thermal loads, and on computation and check of curvature radii of the deformed reflecting surfaces with the design criterion that the curvature radius must be bigger than 200 m. The paper presents detailed thermo-mechanical analysis of the current improved CCR under thermal loads and bolt preloads. The results of the thermo-mechanical analysis were used for the study of the resulting parallelism error of the laser beams with newly developed and more reasonable design criterion

  11. Thermo-mechanical behavior of retro-reflector and resulting parallelism error of laser beams for Wendelstein 7-X interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Peng, X.B., E-mail: pengxb@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, 230031 Hefei Anhui (China); Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Hirsch, M.; Köppen, M.; Fellinger, J.; Bykov, V.; Schauer, F. [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Vliegenthart, W. [TNO, Stieltjesweg 1, P.O. Box 2600, 2628 CK Delft (Netherlands)

    2014-04-15

    Highlights: • The criterion for thermo-mechanical design of W7-X interferometer retro-reflector. • Thermo-mechanical analysis of retro-reflector with two different methods. • The most flexible part in the retro-reflector is spring washer. • Calculation of parallelism error between the incoming and reflected laser beams. • The parallelism error is much lower than the design limit 28 arcs. - Abstract: A 10 channels interferometer will be used in the Wendelstein 7-X (W7-X) for plasma density control and density profile tracking with laser beams passing through the plasma. Due to complex shape of non-planar modular coils and divertor structure, there are no large poloidally opposite ports on the plasma vessel (PV). Therefore 10 in-vessel Corner Cube Retro-reflectors (CCRs) will be used. The CCRs are integrated in the water cooled heat shield and exposed directly to thermal loads from plasma radiation. Thermo-mechanical issues are very important for the design of the CCR because deformation and flatness as well as mutual angles of the three reflecting surfaces would affect the parallelism of the laser beams and the functionality of the interferometer. Intensive work has been done to explore a suitable design for the CCR concerning thermo-mechanical behavior. Previous studies Ye et al. (2008, 2009) and Köppen et al. (2011) focused on structural optimization to decrease thermal stress in the reflecting plates under the thermal loads, and on computation and check of curvature radii of the deformed reflecting surfaces with the design criterion that the curvature radius must be bigger than 200 m. The paper presents detailed thermo-mechanical analysis of the current improved CCR under thermal loads and bolt preloads. The results of the thermo-mechanical analysis were used for the study of the resulting parallelism error of the laser beams with newly developed and more reasonable design criterion.

  12. PID controller auto-tuning based on process step response and damping optimum criterion.

    Science.gov (United States)

    Pavković, Danijel; Polak, Siniša; Zorc, Davor

    2014-01-01

    This paper presents a novel method of PID controller tuning suitable for higher-order aperiodic processes and aimed at step response-based auto-tuning applications. The PID controller tuning is based on the identification of so-called n-th order lag (PTn) process model and application of damping optimum criterion, thus facilitating straightforward algebraic rules for the adjustment of both the closed-loop response speed and damping. The PTn model identification is based on the process step response, wherein the PTn model parameters are evaluated in a novel manner from the process step response equivalent dead-time and lag time constant. The effectiveness of the proposed PTn model parameter estimation procedure and the related damping optimum-based PID controller auto-tuning have been verified by means of extensive computer simulations. © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  13. Thermomechanical treatment of welded joints of aluminum-lithium alloys modified by scandium

    Science.gov (United States)

    Malikov, A. G.

    2017-12-01

    At present, the aeronautical equipment manufacture involves up-to-date high-strength aluminum alloys of decreased density resulting from the lithium admixture. Various technologies of fusible welding of these alloys are being developed. The paper presents experimental investigations of the optimization of the laser welding of aluminum alloys with the scandium-modified welded joint after thermomechanical treatment. The effect of scandium on the micro- and macrostructure is studied along with strength characteristics of the welded joint. It is found that thermomechanical treatment allows us to obtain the strength of the welded joint 0.89 for the Al-Mg-Li system and 0.99 for the Al-Cu-Li system with the welded joint modified by scandium in comparison with the base alloy after treatment.

  14. Ultrasonic transesterification of Jatrophacurcas L. oil to biodiesel by a two-step process

    International Nuclear Information System (INIS)

    Deng Xin; Fang Zhen; Liu Yunhu

    2010-01-01

    Transesterification of high free fatty acid content Jatropha oil with methanol to biodiesel catalyzed directly by NaOH and high-concentrated H 2 SO 4 or by two-step process were studied in an ultrasonic reactor at 60 deg. C. If NaOH was used as catalyst, biodiesel yield was only 47.2% with saponification problem. With H 2 SO 4 as catalyst, biodiesel yield was increased to 92.8%. However, longer reaction time (4 h) was needed and the biodiesel was not stable. A two-step, acid-esterification and base-transesterification process was further used for biodiesel production. It was found that after the first-step pretreatment with H 2 SO 4 for 1 h, the acid value of Jatropha oil was reduced from 10.45 to 1.2 mg KOH/g, and subsequently, NaOH was used for the second-step transesterification. Stable and clear yellowish biodiesel was obtained with 96.4% yield after reaction for 0.5 h. The total production time was only 1.5 h that is just half of the previous reported. The two-step process with ultrasonic radiation is effective and time-saving for biodiesel production from Jatropha oil.

  15. Thermo-mechanical modelling of salt caverns due to fluctuating loading conditions.

    Science.gov (United States)

    Böttcher, N.

    2015-12-01

    This work summarizes the development and application of a numerical model for the thermo-mechanical behaviour of salt caverns during cyclic gas storage. Artificial salt caverns are used for short term energy storage, such as power-to-gas or compressed air energy storage. Those applications are characterized by highly fluctuating operation pressures due to the unsteady power levels of power plants based on renewable energy. Compression and expansion of the storage gases during loading and unloading stages lead to rapidly changing temperatures in the host rock of the caverns. This affects the material behaviour of the host rock within a zone that extends several meters into the rock mass adjacent to the cavern wall, and induces thermo-mechanical stresses and alters the creep response.The proposed model features the thermodynamic behaviour of the storage medium, conductive heat transport in the host rock, as well as temperature dependent material properties of rock salt using different thermo-viscoplastic material models. The utilized constitutive models are well known and state-of-the-art in various salt mechanics applications. The model has been implemented into the open-source software platform OpenGeoSys. Thermal and mechanical processes are solved using a finite element approach, coupled via a staggered coupling scheme. The simulation results allow the conclusion, that the cavern convergence rate (and thus the efficiency of the cavern) is highly influenced by the loading cycle frequency and the resulting gas temperatures. The model therefore allows to analyse the influence of operation modes on the cavern host rock or on neighbouring facilities.

  16. Application of an enriched FEM technique in thermo-mechanical contact problems

    Science.gov (United States)

    Khoei, A. R.; Bahmani, B.

    2018-02-01

    In this paper, an enriched FEM technique is employed for thermo-mechanical contact problem based on the extended finite element method. A fully coupled thermo-mechanical contact formulation is presented in the framework of X-FEM technique that takes into account the deformable continuum mechanics and the transient heat transfer analysis. The Coulomb frictional law is applied for the mechanical contact problem and a pressure dependent thermal contact model is employed through an explicit formulation in the weak form of X-FEM method. The equilibrium equations are discretized by the Newmark time splitting method and the final set of non-linear equations are solved based on the Newton-Raphson method using a staggered algorithm. Finally, in order to illustrate the capability of the proposed computational model several numerical examples are solved and the results are compared with those reported in literature.

  17. Production by thermo-mechanical process and stability in crude petroleum studies of Ba{sub 2}AlZrO{sub 5,5} ceramics; Producao por processo termo-mecanico e estudos de estabilidade em petroleo cru da ceramica Ba{sub 2}AlZrO{sub 5,5}

    Energy Technology Data Exchange (ETDEWEB)

    Yadava, Y.P.; Bezerra, L.P.; Ferreira, R.A.S., E-mail: yadava@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    The necessity of developing technologies that makes possible the petroleum wells exploration is very important. Knowing that those are hostile environments is necessary ta find materials that are able to resist to those environment conditions. In this way we worked on the fabrication of ceramic embedding temperature sensors for petroleum industry. The present work looks for the fabrication of Ba{sub 2}AlZrO{sub 5,5} ceramic by thermo-mechanical process and the study of it's stability in crude petroleum. The Ba{sub 2}AlZrO{sub 5,5} was fabricated by thermo-mechanical process. The ceramic powder was calcined and then the granulometry was analyzed by laser. The samples were compacted, sintered and the microstructure and mechanical properties were characterized. The ceramic stability study in crude petroleum was done and the ceramic was analyzed by X-Ray diffraction and Vickers micro hardness The results shows that the ceramic is stable in crude petroleum. (author)

  18. Thermomechanical and Environmental Durability of Environmental Barrier Coated Ceramic Matrix Composites Under Thermal Gradients

    Science.gov (United States)

    Zhu, Dongming; Bhatt, Ramakrishna T.; Harder, Bryan

    2016-01-01

    This paper presents the developments of thermo-mechanical testing approaches and durability performance of environmental barrier coatings (EBCs) and EBC coated SiCSiC ceramic matrix composites (CMCs). Critical testing aspects of the CMCs will be described, including state of the art instrumentations such as temperature, thermal gradient, and full field strain measurements; materials thermal conductivity evolutions and thermal stress resistance; NDE methods; thermo-mechanical stress and environment interactions associated damage accumulations. Examples are also given for testing ceramic matrix composite sub-elements and small airfoils to help better understand the critical and complex CMC and EBC properties in engine relevant testing environments.

  19. Efficient Hydrolysis of Rice Straw into Xylose and Glucose by a Two-step Process

    Directory of Open Access Journals (Sweden)

    YAN Lu-lu

    2016-07-01

    Full Text Available The hydrolysis of rice straw into xylose and glucose in dilute sulfuric acid aqueous solution was studied with a two-step process in batch autoclave reactor. The results showed that compared with the traditional one-step acid hydrolysis, both xylose and glucose could be produced in high yields from rice straw by using the two-step acid hydrolysis process. The effects of reaction temperature, reaction time, the amount of rice straw and acid concentration on the hydrolysis of rice straw were systematically studied, and showed that except initial rice straw loading amount, the other parameters had remarkable influence on the products distribution and yields. In the first-step of the hydrolysis process, a high xylose yield of 162.6 g·kg-1 was obtained at 140℃ after 120 min reaction time. When the solid residues from the first step were subjected to a second-step hydrolysis, a glucose yield as high as 216.5 g·kg-1 could be achieved at 180℃ after 120 min. This work provides a promising strategy for the efficient and value-added utilization of agricultural wastes such as rice straw.

  20. Enhancing the ABAQUS Thermomechanics Code to Simulate Multidimensional Steady and Transient Fuel Rod Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, R.L.; Knoll, D.A. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415-3855 (United States)

    2009-06-15

    convective heat transfer boundary is applied to the clad outer wall. Energy generation in the fuel is specified using a spatially uniform volumetric fission rate. The analysis includes three time periods: an initial rise to power from ambient conditions, steady operation to a burnup of approximately 47 MWd/kgU, and then a power ramp and 12 hr hold. Results are presented at various stages of burnup during steady operation and then at the end of the power-ramp and hold. The 2D axisymmetric model permits an in-depth view of the evolving temperature and stress fields at the so called 'triple point', where the ends of two adjacent pellets contact the clad. Displacement and temperature results clearly demonstrate the importance of fully-coupled thermomechanics as the gap narrows and contact occurs. The clad axial stress in this region evolves from bending, during initial contact, to full tension, as the fuel and clad are mechanically coupled via friction and fuel swelling results in axial clad displacement. A plot of the clad radial displacement along the axial length shows initial uniform clad creep-down during steady operation, the effects of initial pellet-clad contact at the pellet ends (triple points), eventual full pellet/clad contact, and significant increased displacement during power ramping. The expected 'bamboo' profile along the clad length is clearly demonstrated. An important point is that ABAQUS implicit numeric and error-based time step control permits time step sizes ranging from less than 0.1 s, during power-up, to greater than 10 days, during steady operation. The code can easily accommodate combined steady and transient reactor operations. Results from a multiple pellet simulation demonstrate the importance of a multidimensional fully coupled thermomechanics treatment. Interestingly, many of the inherent deficiencies in existing codes are, in fact, ABAQUS strengths. (authors)

  1. Thermomechanical fatigue and damage mechanisms in Sanicro 25 steel

    Czech Academy of Sciences Publication Activity Database

    Petráš, Roman; Škorík, Viktor; Polák, Jaroslav

    2016-01-01

    Roč. 650, JAN (2016), s. 52-62 ISSN 0921-5093 R&D Projects: GA MŠk(CZ) EE2.3.30.0063; GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : thermomechanical fatigue * Sanicro 25 steel * damage mechanism * FIB cutting * localized oxidation-cracking Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 3.094, year: 2016

  2. Thermo-Mechanical Fatigue Crack Growth of RR1000

    OpenAIRE

    Christopher John Pretty; Mark Thomas Whitaker; Steve John Williams

    2017-01-01

    Non-isothermal conditions during flight cycles have long led to the requirement for thermo-mechanical fatigue (TMF) evaluation of aerospace materials. However, the increased temperatures within the gas turbine engine have meant that the requirements for TMF testing now extend to disc alloys along with blade materials. As such, fatigue crack growth rates are required to be evaluated under non-isothermal conditions along with the development of a detailed understanding of related failure mechan...

  3. Positive steps turning into a process

    Directory of Open Access Journals (Sweden)

    Božičević Goran

    2004-01-01

    Full Text Available The conclusion of the research conducted in Croatia for QPSW in 2003 is there is no systematic, accountable and structural confrontation with the past in Croatia, but there is growing concern within the civil society about the problems incurred by the lack of such a confrontation. Two different approaches can be discerned: individual work with particular persons or target groups and advocacy that could influence the alteration of the public opinion and decision-making. Both levels are necessary and they should unfold simultaneously. The systematization and regional cooperation of documentation centers, cooperation between victim organizations and peace initiatives, the inclusion of former warriors into peace building processes the cooperation of artists and activists - represent some of the new and promising steps on the civilian scene in Croatia. The constant strengthening of the independent media and the judiciary, coupled with constant efforts on both levels - the personal and the public - raises hopes that the confrontation with the past in Croatia is a process and not a trend.

  4. Preparation of biodiesel from waste cooking oil via two-step catalyzed process

    International Nuclear Information System (INIS)

    Wang Yong; Liu Pengzhan; Ou Shiyi; Zhang Zhisen

    2007-01-01

    Waste cooking oils (WCO), which contain large amounts of free fatty acids produced in restaurants, are collected by the environmental protection agency in the main cities of China and should be disposed in a suitable way. In this research, a two step catalyzed process was adopted to prepare biodiesel from waste cooking oil whose acid value was 75.92 ± 0.036 mgKOH/g. The free fatty acids of WCO were esterified with methanol catalyzed by ferric sulfate in the first step, and the triglycerides (TGs) in WCO were transesterified with methanol catalyzed by potassium hydroxide in the second step. The results showed that ferric sulfate had high activity to catalyze the esterification of free fatty acids (FFA) with methanol, The conversion rate of FFA reached 97.22% when 2 wt% of ferric sulfate was added to the reaction system containing methanol to TG in10:1 (mole ratio) composition and reacted at 95 deg. C for 4 h. The methanol was vacuum evaporated, and transesterification of the remained triglycerides was performed at 65 deg. C for 1 h in a reaction system containing 1 wt% of potassium hydroxide and 6:1 mole ratio of methanol to TG. The final product with 97.02% of biodiesel, obtained after the two step catalyzed process, was analyzed by gas chromatography. This new process has many advantages compared with the old processes, such as no acidic waste water, high efficiency, low equipment cost and easy recovery of the catalyst

  5. High pressure as an alternative processing step for ham production.

    Science.gov (United States)

    Pingen, Sylvia; Sudhaus, Nadine; Becker, André; Krischek, Carsten; Klein, Günter

    2016-08-01

    As high pressure processing (HPP) is becoming more and more important in the food industry, this study examined the application of HPP (500 and 600MPa) as a manufacturing step during simulated ham production. By replacing conventional heating with HPP steps, ham-like texture or color attributes could not be achieved. HPP products showed a less pale, less red appearance, softer texture and higher yields. However, a combination of mild temperature (53°C) and 500MPa resulted in parameters more comparable to cooked ham. We conclude that HPP can be used for novel food development, providing novel textures and colors. However, when it comes to ham production, a heating step seems to be unavoidable to obtain characteristic ham properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Ultrasonic transesterification of Jatrophacurcas L. oil to biodiesel by a two-step process

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xin; Fang, Zhen; Liu, Yun-hu [Biomass Group, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefulu, Kunming, Yunnan Province 650223 (China)

    2010-12-15

    Transesterification of high free fatty acid content Jatropha oil with methanol to biodiesel catalyzed directly by NaOH and high-concentrated H{sub 2}SO{sub 4} or by two-step process were studied in an ultrasonic reactor at 60 C. If NaOH was used as catalyst, biodiesel yield was only 47.2% with saponification problem. With H{sub 2}SO{sub 4} as catalyst, biodiesel yield was increased to 92.8%. However, longer reaction time (4 h) was needed and the biodiesel was not stable. A two-step, acid-esterification and base-transesterification process was further used for biodiesel production. It was found that after the first-step pretreatment with H{sub 2}SO{sub 4} for 1 h, the acid value of Jatropha oil was reduced from 10.45 to 1.2 mg KOH/g, and subsequently, NaOH was used for the second-step transesterification. Stable and clear yellowish biodiesel was obtained with 96.4% yield after reaction for 0.5 h. The total production time was only 1.5 h that is just half of the previous reported. The two-step process with ultrasonic radiation is effective and time-saving for biodiesel production from Jatropha oil. (author)

  7. Ultrasonic transesterification of Jatrophacurcas L. oil to biodiesel by a two-step process

    Energy Technology Data Exchange (ETDEWEB)

    Deng Xin [Biomass Group, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefulu, Kunming, Yunnan Province 650223 (China); Fang Zhen, E-mail: zhenfang@xtbg.ac.c [Biomass Group, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefulu, Kunming, Yunnan Province 650223 (China); Liu Yunhu [Biomass Group, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 88 Xuefulu, Kunming, Yunnan Province 650223 (China)

    2010-12-15

    Transesterification of high free fatty acid content Jatropha oil with methanol to biodiesel catalyzed directly by NaOH and high-concentrated H{sub 2}SO{sub 4} or by two-step process were studied in an ultrasonic reactor at 60 deg. C. If NaOH was used as catalyst, biodiesel yield was only 47.2% with saponification problem. With H{sub 2}SO{sub 4} as catalyst, biodiesel yield was increased to 92.8%. However, longer reaction time (4 h) was needed and the biodiesel was not stable. A two-step, acid-esterification and base-transesterification process was further used for biodiesel production. It was found that after the first-step pretreatment with H{sub 2}SO{sub 4} for 1 h, the acid value of Jatropha oil was reduced from 10.45 to 1.2 mg KOH/g, and subsequently, NaOH was used for the second-step transesterification. Stable and clear yellowish biodiesel was obtained with 96.4% yield after reaction for 0.5 h. The total production time was only 1.5 h that is just half of the previous reported. The two-step process with ultrasonic radiation is effective and time-saving for biodiesel production from Jatropha oil.

  8. Non-destructive thermo-mechanical behavior assessment of glass-ceramics for dental applications

    Science.gov (United States)

    Kordatos, E. Z.; Abdulkadhim, Z.; Feteira, A. M.

    2017-05-01

    Every year millions of people seek dental treatment to either repair damaged, unaesthetic and dysfunctional teeth or replace missing natural teeth. Several dental materials have been developed to meet the stringent requirements in terms of mechanical properties, aesthetics and chemical durability in the oral environment. Glass-ceramics exhibit a suitable combination of these properties for dental restorations. This research is focused on the assessment of the thermomechanical behavior of bio-ceramics and particularly lithium aluminosilicate glass-ceramics (LAS glass-ceramics). Specifically, methodologies based on Infrared Thermography (IRT) have been applied in order the structure - property relationship to be evaluated. Non-crystallized, partially crystallized and fully crystallized glass-ceramic samples have been non-destructively assessed in order their thermo-mechanical behavior to be associated with their micro-structural features.

  9. Core-shell polymer nanorods by a two-step template wetting process

    International Nuclear Information System (INIS)

    Dougherty, S; Liang, J

    2009-01-01

    One-dimensional core-shell polymer nanowires offer many advantages and great potential for many different applications. In this paper we introduce a highly versatile two-step template wetting process to fabricate two-component core-shell polymer nanowires with controllable shell thickness. PLLA and PMMA were chosen as model polymers to demonstrate the feasibility of this process. Solution wetting with different concentrations of polymer solutions was used to fabricate the shell layer and melt wetting was used to fill the shell with the core polymer. The shell thickness was analyzed as a function of the polymer solution concentration and viscosity, and the core-shell morphology was observed with TEM. This paper demonstrates the feasibility of fabricating polymer core-shell nanostructures using our two-step template wetting process and opens the arena for optimization and future experiments with polymers that are desirable for specific applications.

  10. Thermomechanical interactions of particle bed-structural wall in a layered configuration. Pt. 1. Effect of particle bed thermal expansions

    International Nuclear Information System (INIS)

    Tehranian, F.

    1995-01-01

    Materials in the form of particle beds have been considered for shielding and tritium breeding as well as neutron multiplication in many of the conceptual reactor design studies. As the level of effort of the fusion blanket community in the area of out-of-pile and in-pile (ITER) testing of integrated test modules increases, so does the need for modelling capability for predicting the thermomechanical responses of the test modules under reactor environment.In this study, the thermomechanical responses of a particle bed-structural wall system in a layered configuration, subjected to bed temperature rise and/or external coolant pressure, were considered. Equations were derived which represent the dependence of the particle-to-particle and particle-to-wall contact forces and areas on the structural wall deformations and in turn on the thermomechanical loads. Using the derived equations, parametric analyses were performed to study the variations in the thermomechanical response quantities of a beryllium particle bed-stainless steel structural wall when subjected to thermomechanical loads. The results are presented in two parts. In Part I, presented in this paper, the derivation of the analytical equations and the effects of bed temperature rise are discussed. In Part II of this study, also presented in this symposium, the effects of external coolant pressure as well as the combined effects of bed temperature rise and coolant pressure on the thermomechanical responses are given.It is shown that, depending on the stiffness of the structural walls, uniform bed temperature rises in the range 100-400 C result in non-uniform effective thermal properties through the prticle bed and could increase the bed effective thermal conductivity by a factor of 2-5 and the bed-wall interface thermal conductance by even a larger factor. (orig.)

  11. Thermomechanical Behavior of Monolithic SN-AG-CU Solder and Copper Fiber Reinforced Solders

    National Research Council Canada - National Science Library

    Reuse, Rolando

    2005-01-01

    .... The thermomechanical cycling in the solder causes numerous reliability challenges, mostly because of the mismatch of the coefficient of thermal expansion between the silicon chip and the substrate...

  12. The effect of thermomechanical processing on the microstructure and mechanical properties of the nanocrystalline TiNiCo shape memory alloy

    International Nuclear Information System (INIS)

    Mohammad Sharifi, E.; Kermanpur, A.; Karimzadeh, F.

    2014-01-01

    The effect of thermomechanical processing comprising cold rolling followed by annealing on the microstructural evolution and mechanical behavior of the Ti 50 Ni 48 Co 2 shape memory alloy was investigated. The annealed specimens were subjected to cold rolling at room temperature with various thickness reductions up to 70%. Transmission electron microscopy revealed that the initial deformation mechanism of Ti 50 Ni 48 Co 2 alloy during cold rolling was stress-induced martensitic transformation followed by plastic deformation of martensite via dislocation slip and subsequent martensite to austenite transformation via the reverse transformation after unloading. Microstructural investigations showed that by increasing the cold deformation, a high density of dislocations is accumulated, leading gradually to nanocrystallization and amorphization. After annealing at 400 °C for 1 h, the amorphous phase formed in the cold rolled specimens was completely crystallized and an entirely nanocrystalline structure was achieved. Results showed that the stress–strain curves of the cold rolled specimens exhibited plastic deformation of austenite without the stress plateau region. However, the stress plateau appeared in the stress–strain curves of the annealed specimens, whose stress level and length were increased with increasing thickness reduction

  13. Surface finishing and levelling of thermomechanically hardened rolled steel

    International Nuclear Information System (INIS)

    Grosval'd, V.G.; Bashchenko, A.P.; Grishkov, A.I.; Gutnik, M.V.; Kanevskij, B.L.; Nikozov, A.I.; Sedov, N.D.; Prosin, K.A.; Safonov, L.I.

    1975-01-01

    The finishing of high-strength merchant shapes from alloy steel was tried out under industrial conditions with the equipment of metallurgical plants. After thermomechanical hardening in the production line of the rolling mill, 30KhGSN2A and 40Kh1NVA steel rounds 32 and 31 mm in diameter were straightened on a two-roller straightening machine designed by the All-Union Scientific Research Institute for Metallurgical Machinery (VNII Metmash). This made possible subsequent turning and grinding of the rods. The conditions of straightening, turning and grinding have been worked so as to obtain thermomechanically strengthened and ground rolled products approximating the gauged and ground metal in shape geometry and surface finish. It is shown that the labour-consuming operation of turning can be eliminated by reducing the machining pass of the rolled product, and this lowers the labour required for the finishing operations by 75%. After grinding with 40- and 25-grain abrasive wheels, high strength rolled shapes were obtained with a diameter of 30-0.20 mm and a surface finish of class 6-5 satisfying the technical specifications. (author)

  14. Effect of the processing steps on compositions of table olive since harvesting time to pasteurization.

    Science.gov (United States)

    Nikzad, Nasim; Sahari, Mohammad A; Vanak, Zahra Piravi; Safafar, Hamed; Boland-nazar, Seyed A

    2013-08-01

    Weight, oil, fatty acids, tocopherol, polyphenol, and sterol properties of 5 olive cultivars (Zard, Fishomi, Ascolana, Amigdalolia, and Conservalia) during crude, lye treatment, washing, fermentation, and pasteurization steps were studied. Results showed: oil percent was higher and lower in Ascolana (crude step) and in Fishomi (pasteurization step), respectively; during processing steps, in all cultivars, oleic, palmitic, linoleic, and stearic acids were higher; the highest changes in saturated and unsaturated fatty acids were in fermentation step; the highest and the lowest ratios of ω3 / ω6 were in Ascolana (washing step) and in Zard (pasteurization step), respectively; the highest and the lowest tocopherol were in Amigdalolia and Fishomi, respectively, and major damage occurred in lye step; the highest and the lowest polyphenols were in Ascolana (crude step) and in Zard and Ascolana (pasteurization step), respectively; the major damage among cultivars occurred during lye step, in which the polyphenol reduced to 1/10 of first content; sterol did not undergo changes during steps. Reviewing of olive patents shows that many compositions of fruits such as oil quality, fatty acids, quantity and its fraction can be changed by alteration in cultivar and process.

  15. Magnitude of long-term non-lithostatic pressure variations in lithospheric processes: insight from thermo-mechanical subduction/collision models

    Science.gov (United States)

    Gerya, Taras

    2014-05-01

    On the one hand, the principle of lithostatic pressure is habitually used in metamorphic geology to calculate paleo-depths of metamorphism from mineralogical pressure estimates given by geobarometry. On the other hand, it is obvious that this lithostatic (hydrostatic) pressure principle should only be valid for an ideal case of negligible deviatoric stresses during the long-term development of the entire tectono-metamorphic system - the situation, which newer comes to existence in natural lithospheric processes. The question is therefore not "Do non-lithostatic pressure variations exist?" but " What is the magnitude of long-term non-lithostatic pressure variations in various lithospheric processes, which can be recorded by mineral equilibria of respective metamorphic rocks?". The later question is, in particular, relevant for various types of high-pressure (HP) and ultrahigh-pressure (UHP) rocks, which are often produced in convergent plate boundary settings (e.g., Hacker and Gerya, 2013). This question, can, in particular, be answered with the use of thermo-mechanical models of subduction/collision processes employing realistic P-T-stress-dependent visco-elasto-brittle/plastic rheology of rocks. These models suggest that magnitudes of pressure deviations from lithostatic values can range >50% underpressure to >100% overpressure, mainly in the regions of bending of rheologically strong mantle lithosphere (Burg and Gerya, 2005; Li et al., 2010). In particular, strong undepresures along normal faults forming within outer rise regions of subducting plates can be responsible for downward water suction and deep hydration of oceanic slabs (Faccenda et al., 2009). Weaker HP and UHP rocks of subduction/collision channels are typically subjected to lesser non-lithostatic pressure variations with characteristic magnitudes ranging within 10-20% from the lithostatic values (Burg and Gerya, 2005; Li et al., 2010). The strength of subducted crustal rocks and the degree of

  16. Thermo-mechanical design of the extraction grids for RF negative ion source at HUST

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Chen; Liu, Kaifeng, E-mail: kfliuhust@hust.edu.cn; Li, Dong; Mei, Zhiyuan; Zhang, Zhe; Chen, Dezhi

    2017-01-15

    Highlights: • An extraction system with cooling channels has been designed for HUST negative ion source. • Corresponding heat loads onto three grids has been used in thermo-mechanical analysis. • The analysis results could be very useful for driving the engineering design. - Abstract: Huazhong University of Science and Technology (HUST) is developing a small radio frequency negative ion source experimental setup to promote research on neutral beam injection ion sources. The extraction system for the negative ion source is the key component to obtain the negative ions. The extraction system is composed of three grids: the plasma grid, the extraction grid and the grounded grid. Each grid is impacted by different heat loads. As the grids have to fulfil specific requirements regarding ion extraction, beam optics, and thermo-mechanical issues, grid cooling systems have been included for ensuring reliable operation. This paper focuses on the thermo-hydraulic and thermo-mechanical design of the grids. Finite element calculations have been carried out to analyse the temperature and deformation of the grids under heat loads using the fluid dynamics code CFX. Based on these results, the cooling circuit design and cooling parameters are optimised to satisfy the grid requirements.

  17. Preliminary AD-Horn Thermomechanical and Electrodynamic Simulations

    CERN Document Server

    AUTHOR|(CDS)2095747; Horvath, David; Calviani, Marco

    2016-01-01

    As part of the Antiproton Decelerator (AD) target area consolidation activities planned for LS2, it has been necessary to perform a comprehensive study of the thermo-structural behaviour of the AD magnetic horn during operation, in order to detail specific requirements for the upgrade projects and testing procedures. The present work illustrates the preliminary results of the finite element analysis carried out to evaluate the thermal and structural behaviour of the device, as well as the methodology used to model and solve the thermomechanical and electrodynamic simulations performed in the AD magnetic horn.

  18. Thermal and thermo-mechanical behavior of butyl based rubber exposed to silicon oil at elevated temperature

    International Nuclear Information System (INIS)

    Ali, S.; Ramzan, S.; Raza, R.; Ahmed, F.; Hussain, R.; Ullah, S.; Ali, S.

    2013-01-01

    Silica reinforced rubbers are used as chemical resistant seals at high temperature. In this study the effect of alkali and silicon oil on the thermal and thermo-mechanical properties of the silica reinforced butyl rubber exposed as an interface between two liquid media at elevated temperature is investigated. Rubber bladder containing alkaline solution was immersed in silicon oil at 195+-5 degree C for multiple cycles and loss in its thermal, thermo-mechanical and mechanical properties were studied by TGA, DMA and Tinius Olsen Testing Machine supported by FTIR and Optical microscopy. It was observed that the thermal and thermo-mechanical properties of butyl rubber were negatively affected due to leaching out of silica filler embedded in an organic matrix at elevated temperature. The thermal stability of exposed rubber was decreased around 200 degree C and the loss of storage modulus was observed up to 99.5% at -59 degree C. (author)

  19. Two-step estimation procedures for inhomogeneous shot-noise Cox processes

    DEFF Research Database (Denmark)

    Prokesová, Michaela; Dvorák, Jirí; Jensen, Eva B. Vedel

    In the present paper we develop several two-step estimation procedures for inhomogeneous shot-noise Cox processes. The intensity function is parametrized by the inhomogeneity parameters while the pair-correlation function is parametrized by the interaction parameters. The suggested procedures...

  20. Comparison of microbial community shifts in two parallel multi-step drinking water treatment processes.

    Science.gov (United States)

    Xu, Jiajiong; Tang, Wei; Ma, Jun; Wang, Hong

    2017-07-01

    Drinking water treatment processes remove undesirable chemicals and microorganisms from source water, which is vital to public health protection. The purpose of this study was to investigate the effects of treatment processes and configuration on the microbiome by comparing microbial community shifts in two series of different treatment processes operated in parallel within a full-scale drinking water treatment plant (DWTP) in Southeast China. Illumina sequencing of 16S rRNA genes of water samples demonstrated little effect of coagulation/sedimentation and pre-oxidation steps on bacterial communities, in contrast to dramatic and concurrent microbial community shifts during ozonation, granular activated carbon treatment, sand filtration, and disinfection for both series. A large number of unique operational taxonomic units (OTUs) at these four treatment steps further illustrated their strong shaping power towards the drinking water microbial communities. Interestingly, multidimensional scaling analysis revealed tight clustering of biofilm samples collected from different treatment steps, with Nitrospira, the nitrite-oxidizing bacteria, noted at higher relative abundances in biofilm compared to water samples. Overall, this study provides a snapshot of step-to-step microbial evolvement in multi-step drinking water treatment systems, and the results provide insight to control and manipulation of the drinking water microbiome via optimization of DWTP design and operation.

  1. Decarbonation and carbonation processes in the slab and mantle wedge - insights from thermomechanical modeling

    Science.gov (United States)

    Gonzalez, C. M.; Gorczyk, W.; Connolly, J. A.; Gerya, T.; Hobbs, B. E.; Ord, A.

    2013-12-01

    Subduction zones offer one of the most geologically active and complex systems to investigate. They initiate a process in which crustal sediments are recycled, mantle heterogeneities arise, and mantle wedge refertilization occurs via slab derived volatiles and magma generation. Slab derived volatiles, consisting primarily of H2O - CO2 fluids, are especially critical in subduction evolution as they rheologically weaken the mantle wedge, decrease solidus temperatures, and rock-fluid interactions result in metasomatism. While the effects of H2O in these processes have been well studied in the past decades, CO2's role remains open for much scientific study. This is partly attributed to the sensitivity of decarbonation to the thermal gradient of the subduction zone, bulk compositions (sediments, basalts, peridotites) and redox state of the mantle. Here we show benchmarking results of a subduction scenario that implements carbonation-decarbonation reactions into a fully coupled petrological-thermomechanical numerical modeling code. We resolve stable mineralogy and extract rock properties via Perple_X at a resolution of 5°C and 25 MPa. The numerical technique employed is a characteristics-based marker-in-cell technique with conservative finite-differences that includes visco-elastic-plastic rheologies (I2ELVIS). The devolatilized fluids are tracked via markers that are either generated or consumed based on P-T conditions. The fluids are also allowed to freely advect within the velocity field. The hosts for CO2 in this system are computed via GLOSS average sediments (H2O: 7.29 wt% & CO2: 3.01 wt%), metabasalts ( H2O: 2.63 & CO2: 2.90 wt%), and ophicarbonates (H2O: 1.98 wt% & CO2: 5.00 wt%). Our results demonstrate the feasibility of applying this decarbonation-carbonation numerical method to a range of geodynamic scenarios that simulate the removal of CO2 from the subducting slab. Such applicable scenarios include sediment diapirism into the convecting wedge and better

  2. Thermo-mechanical properties and integrity of metallic interconnects in microelectronics

    Science.gov (United States)

    Ege, Efe Sinan

    In this dissertation, combined numerical (Finite Element Method) and experimental efforts were undertaken to study thermo-mechanical behavior in microelectronic devices. Interconnects, including chip-level metallization and package-level solder joints, are used to join many of the circuit parts in modern equipment. The dissertation is structured into six independent studies after the introductory chapter. The first two studies focus on thermo-mechanical fatigue of solder joints. Thermo-mechanical fatigue, in the form of damage along a microstructurally coarsened region in tin-lead solder, is analyzed along with the effects of intermetallic morphology. Also, lap-shear testing is modeled to characterize the joint and to investigate the validity of experimental data from different solder and substrate geometries. In the third study, the effects of pre-machined holes on strain localization and overall ductility in bulk eutectic tin-lead alloy is examined. Finite element analyses, taking into account the viscoplastic response, were carried out to provide a mechanistic rationale to corroborate the experimental findings. The fourth study concerns chip-level copper interconnects. Various combinations of oxide and polymer-based low-k dielectric schemes, with and without the thin barrier layers surrounding the Cu line, are considered. Attention is devoted to the thermal stress and strain fields and their dependency on material properties, geometry, and modeling details. This study is followed by a chapter on atomistics of interface-mediated plasticity in thin metallic films. The objective is to gain fundamental insight into the underlying mechanisms affecting the mechanical response of nanoscale thin films. The final study investigates the effect of microstructural heterogeneity on indentation response, for the purpose of raising awareness of the uncertainties involved in applying indentation techniques in probing mechanical properties of miniaturized devices.

  3. Effect of Nb2O5 doping on improving the thermo-mechanical stability of sealing interfaces for solid oxide fuel cells.

    Science.gov (United States)

    Zhang, Qi; Du, Xinhang; Tan, Shengwei; Tang, Dian; Chen, Kongfa; Zhang, Teng

    2017-07-13

    Nb 2 O 5 is added to a borosilicate sealing system to improve the thermo-mechanical stability of the sealing interface between the glass and Fe-Cr metallic interconnect (Crofer 22APU) in solid oxide fuel cells (SOFCs). The thermo-mechanical stability of the glass/metal interface is evaluated experimentally as well as by using a finite element analysis (FEA) method. The sealing glass doped with 4 mol.% Nb 2 O 5 shows the best thermo-mechanical stability, and the sealing couple of Crofer 22APU/glass/GDC (Gd 0.2 Ce 0.8 O 1.9 ) remains intact after 50 thermal cycles. In addition, all sealing couples show good joining after being held at 750 °C for 1000 h. Moreover, the possible mechanism on the thermo-mechanical stability of sealing interface is investigated in terms of stress-based and energy-based perspectives.

  4. Thermo-mechanical response of rigid plastic laminates for greenhouse covering

    Directory of Open Access Journals (Sweden)

    Silvana Fuina

    2016-09-01

    Full Text Available Innovation in the field of protected crops represents an argument of great applied and theoretical research attention due to constantly evolving technologies and automation for higher quality flower and vegetable production and to the corresponding environmental and economic impact. The aim of this paper is to provide an analysis of some thermomechanical properties of rigid polymeric laminates for greenhouses claddings, including innovative tests such as the thermographic ones. Four types of laminates have been analysed: two polycarbonates, a polymethylmethacrylate and a polyethylene terephthalate (PET. The tests gave interesting results on different important properties, such as radiometric properties, limit stresses, strains and ductility. Moreover, a direct comparison of infrared images and force elongation curves gave important information on the relation of the (localised or homogeneous damage evolution, with both an applicative and theoretical implication. Finally, even if to the authors knowledge at present there are no examples of using PET for covering greenhouses, the results of this paper indicates the thermomechanical and radiometric characteristics of this material make it interesting for agricultural applications.

  5. Thermo-mechanical analysis of RMP coil system for EAST tokamak

    International Nuclear Information System (INIS)

    Wang, Songke; Ji, Xiang; Song, Yuntao; Zhang, Shanwen; Wang, Zhongwei; Sun, Youwen; Qi, Minzhong; Liu, Xufeng; Wang, Shengming; Yao, Damao

    2014-01-01

    Highlights: • Thermal design requirements for EAST RMP coils are summarized. • Cooling parameters based on both theoretical and numerical solutions are determined. • Compromise between thermal design and structural design is made on number of turns. • Thermo-mechanical calculations are made to validate its structural performance. - Abstract: Resonant magnetic perturbation (RMP) has been proved to be an efficient approach on edge localized modes (ELMs) control, resistive wall mode (RWM) control, and error field correction (EFC), RMP coil system under design in EAST tokamak will realize the above-mentioned multi-functions. This paper focuses on the thermo-mechanical analysis of EAST RMP coil system on the basis of sensitivity analysis, both normal and off-normal working conditions are considered. The most characteristic set of coil system is chosen with a complete modelling by means of three-dimensional (3D) finite element method, thermo-hydraulic and thermal-structural performances are investigated adequately, both locally and globally. The compromise is made between thermal performance and structural design requirements, and the results indicate that the optimized design is feasible and reasonable

  6. Thermo-mechanical simulation and parameters optimization for beam blank continuous casting

    International Nuclear Information System (INIS)

    Chen, W.; Zhang, Y.Z.; Zhang, C.J.; Zhu, L.G.; Lu, W.G.; Wang, B.X.; Ma, J.H.

    2009-01-01

    The objective of this work is to optimize the process parameters of beam blank continuous casting in order to ensure high quality and productivity. A transient thermo-mechanical finite element model is developed to compute the temperature and stress profile in beam blank continuous casting. By comparing the calculated data with the metallurgical constraints, the key factors causing defects of beam blank can be found out. Then based on the subproblem approximation method, an optimization program is developed to search out the optimum cooling parameters. Those optimum parameters can make it possible to run the caster at its maximum productivity, minimum cost and to reduce the defects. Now, online verifying of this optimization project has been put in practice, which can prove that it is very useful to control the actual production

  7. Thermomechanical Analysis of Shape-Memory Composite Tape Spring

    Science.gov (United States)

    Yang, H.; Wang, L. Y.

    2013-06-01

    Intelligent materials and structures have been extensively applied for satellite designs in order to minimize the mass and reduce the cost in the launch of the spacecraft. Elastic memory composites (EMCs) have the ability of high-strain packaging and shape-memory effect, but increase the parts and total weight due to the additional heating system. Shape-memory sandwich structures Li and Wang (J. Intell. Mater. Syst. Struct. 22(14), 1605-1612, 2011) can overcome such disadvantage by using the metal skin acting as the heating element. However, the high strain in the micro-buckled metal skin decreases the deployment efficiency. This paper aims to present an insight into the folding and deployment behaviors of shape-memory composite (SMC) tape springs. A thermomechanical process was analyzed, including the packaging deformation at an elevated temperature, shape frozen at the low temperature and shape recovery after reheating. The result shows that SMC tape springs can significantly decrease the strain concentration in the metal skin, as well as exhibiting excellent shape frozen and recovery behaviors. Additionally, possible failure modes of SMC tape springs were also analyzed.

  8. Discrete pre-processing step effects in registration-based pipelines, a preliminary volumetric study on T1-weighted images.

    Science.gov (United States)

    Muncy, Nathan M; Hedges-Muncy, Ariana M; Kirwan, C Brock

    2017-01-01

    Pre-processing MRI scans prior to performing volumetric analyses is common practice in MRI studies. As pre-processing steps adjust the voxel intensities, the space in which the scan exists, and the amount of data in the scan, it is possible that the steps have an effect on the volumetric output. To date, studies have compared between and not within pipelines, and so the impact of each step is unknown. This study aims to quantify the effects of pre-processing steps on volumetric measures in T1-weighted scans within a single pipeline. It was our hypothesis that pre-processing steps would significantly impact ROI volume estimations. One hundred fifteen participants from the OASIS dataset were used, where each participant contributed three scans. All scans were then pre-processed using a step-wise pipeline. Bilateral hippocampus, putamen, and middle temporal gyrus volume estimations were assessed following each successive step, and all data were processed by the same pipeline 5 times. Repeated-measures analyses tested for a main effects of pipeline step, scan-rescan (for MRI scanner consistency) and repeated pipeline runs (for algorithmic consistency). A main effect of pipeline step was detected, and interestingly an interaction between pipeline step and ROI exists. No effect for either scan-rescan or repeated pipeline run was detected. We then supply a correction for noise in the data resulting from pre-processing.

  9. Two-step estimation for inhomogeneous spatial point processes

    DEFF Research Database (Denmark)

    Waagepetersen, Rasmus; Guan, Yongtao

    This paper is concerned with parameter estimation for inhomogeneous spatial point processes with a regression model for the intensity function and tractable second order properties (K-function). Regression parameters are estimated using a Poisson likelihood score estimating function and in a second...... step minimum contrast estimation is applied for the residual clustering parameters. Asymptotic normality of parameter estimates is established under certain mixing conditions and we exemplify how the results may be applied in ecological studies of rain forests....

  10. Experimental study on the thermo-mechanical behaviour of stiff clay under non-isotropic stress state

    International Nuclear Information System (INIS)

    Tang, Anh Minh; Cui, Yu-Jun; Li, Xiang-Ling

    2012-01-01

    conditions. Hueckel et al. (2009) cited some few laboratory tests where undrained heating was performed on clays under non-isotropic stress state. Some other tests can be found in Monfared et al. (2012). Both works show that heating under non-isotropic stress state and undrained conditions can induce thermal failure in saturated clays. In the present work, the thermo-mechanical behaviour of clays is also investigated but drained conditions were applied. The soil studied was Boom clay, taken form the Mol underground research laboratory operated by EURIDICE in Belgium. Beside common triaxial compression tests performed at various temperatures (ranging from 20 C to 80 C), specific tests were performed under the similar thermo-mechanical loading path as in the near field of the repository. One of these tests is detailed here. A temperature-controlled high-pressure triaxial cell was used in this studied. After the installation of the soil specimen in the cell, the soil was re-saturated under isotropic in situ stress state (2.5 MPa) to reach similar in situ conditions. At the end of the saturation phase (t = 500 h), the confining pressure (p) was 3.5 MPa, the back pressure (u) was 1.0 MPa, and the effective isotropic stress (p-u) was 2.5 MPa. From this state, the deviatoric stress was increased slowly (with a rate of 0.3 kPa/min) to reach 1.6 MPa. This value was then kept constant until the end of the test (figure 1b). This shearing induce axial strain and volumetric strain which stabilised at 2.30% and 0.23% respectively (at t = 1700 h). From this state, the soil temperature, which was kept constant at 25 C from the beginning of the test, was increased step-by-step to 40 C, 60 C, and 80 C. The results show that heating increased the axial strain respectively to 3.10%, 4.10%, and 5.73%. The volumetric behaviour of soil during heating did not show a clear trend, the volumetric strain decreased to 0% at the end of 40 C stage, reached 0.89% at the end of 60 C stage, and reached up to

  11. The RiverFish Approach to Business Process Modeling: Linking Business Steps to Control-Flow Patterns

    Science.gov (United States)

    Zuliane, Devanir; Oikawa, Marcio K.; Malkowski, Simon; Alcazar, José Perez; Ferreira, João Eduardo

    Despite the recent advances in the area of Business Process Management (BPM), today’s business processes have largely been implemented without clearly defined conceptual modeling. This results in growing difficulties for identification, maintenance, and reuse of rules, processes, and control-flow patterns. To mitigate these problems in future implementations, we propose a new approach to business process modeling using conceptual schemas, which represent hierarchies of concepts for rules and processes shared among collaborating information systems. This methodology bridges the gap between conceptual model description and identification of actual control-flow patterns for workflow implementation. We identify modeling guidelines that are characterized by clear phase separation, step-by-step execution, and process building through diagrams and tables. The separation of business process modeling in seven mutually exclusive phases clearly delimits information technology from business expertise. The sequential execution of these phases leads to the step-by-step creation of complex control-flow graphs. The process model is refined through intuitive table and diagram generation in each phase. Not only does the rigorous application of our modeling framework minimize the impact of rule and process changes, but it also facilitates the identification and maintenance of control-flow patterns in BPM-based information system architectures.

  12. Evolution of microstructure and mechanical properties during thermomechanical processing of a low-density multiphase steel for automotive application

    International Nuclear Information System (INIS)

    Rana, R.; Liu, C.; Ray, R.K.

    2014-01-01

    The evolution of the microstructure and mechanical properties in a low-density, low-alloy steel containing 6.57Al–3.34Mn–0.18C (wt.%) has been investigated as a function of processing. The steel was designed to have a duplex microstructure with ferrite as the major phase and austenite as the minor phase within the temperature range 800–1350 °C. The steel was processed to sheet form, which was thermomechanically treated and characterised by a variety of techniques such as optical metallography, scanning electron microscopy, electron backscatter diffraction, electron probe microanalysis, X-ray diffraction, transmission electron microscopy, tensile testing and density and elastic modulus measurements. The amount of austenite was found to decrease with an increase in the annealing temperature. While C and Mn partitioned into the austenite phase, Al partitioned into the ferrite. The tensile elongation increased with an increase in the amount of austenite in the microstructure. However, the austenite showed only a small transformation induced plasticity effect during tensile deformation due to its high stability. After annealing, mostly κ-carbide precipitates with a (Fe + Mn)/Al ratio of 3.6 appeared in the ferrite matrix, along with some cementite and complex carbides. These precipitates became coarser (330 nm) during a short time overageing treatment at 400 °C, causing a significant increase in elongation. The κ-carbides were found to have a close to Nishiyama–Wasserman type orientation relationship with the ferrite matrix. Although the Young’s modulus of the steel dropped due to the large amount of Al added, the reduced density was found to be beneficial for automotive applications, overriding the effect of a drop in Young’s modulus

  13. Application of Laser Pulse Heating to Simulate Thermomechanical Damage at Gun Bore Surfaces

    National Research Council Canada - National Science Library

    Cote, Paul

    2003-01-01

    Laser pulse heating experiments were performed to provide insights into the thermomechanical damage effects that occur at the surface of coated and uncoated gun steel under cyclic rapid heating and cooling...

  14. Towards thermomechanics of fractal media

    Science.gov (United States)

    Ostoja-Starzewski, Martin

    2007-11-01

    Hans Ziegler’s thermomechanics [1,2,3], established half a century ago, is extended to fractal media on the basis of a recently introduced continuum mechanics due to Tarasov [14,15]. Employing the concept of internal (kinematic) variables and internal stresses, as well as the quasiconservative and dissipative stresses, a field form of the second law of thermodynamics is derived. In contradistinction to the conventional Clausius Duhem inequality, it involves generalized rates of strain and internal variables. Upon introducing a dissipation function and postulating the thermodynamic orthogonality on any lengthscale, constitutive laws of elastic-dissipative fractal media naturally involving generalized derivatives of strain and stress can then be derived. This is illustrated on a model viscoelastic material. Also generalized to fractal bodies is the Hill condition necessary for homogenization of their constitutive responses.

  15. Cognitive processing for step precision increases beta and gamma band modulation during overground walking

    DEFF Research Database (Denmark)

    Oliveira, Anderson Souza; Arguissain, Federico Gabriel; Andersen, Ole Kæseler

    2018-01-01

    The aim of this study was to investigate whether cognitive processing for defining step precision during walking could induce changes in electrocortical activity. Ten healthy adults (21-36 years) were asked to walk overground in three different conditions: (1) normal walking in a straight path (N...... activity in cognitive, motor and sensorimotor areas may be relevant to produce patterned and safe locomotion through challenging paths.......The aim of this study was to investigate whether cognitive processing for defining step precision during walking could induce changes in electrocortical activity. Ten healthy adults (21-36 years) were asked to walk overground in three different conditions: (1) normal walking in a straight path (NW....../sensorimotor regions, a phase in the gait cycle in which participants define the correct foot placement for the next step. These results suggest that greater cognitive demands during precision stepping influences electrocortical dynamics especially towards step transitions. Therefore, increased electrocortical...

  16. SPAR-H Step-by-Step Guidance

    Energy Technology Data Exchange (ETDEWEB)

    W. J. Galyean; A. M. Whaley; D. L. Kelly; R. L. Boring

    2011-05-01

    This guide provides step-by-step guidance on the use of the SPAR-H method for quantifying Human Failure Events (HFEs). This guide is intended to be used with the worksheets provided in: 'The SPAR-H Human Reliability Analysis Method,' NUREG/CR-6883, dated August 2005. Each step in the process of producing a Human Error Probability (HEP) is discussed. These steps are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff. The discussions on dependence are extensive and include an appendix that describes insights obtained from the psychology literature.

  17. SPAR-H Step-by-Step Guidance

    International Nuclear Information System (INIS)

    Galyean, W.J.; Whaley, A.M.; Kelly, D.L.; Boring, R.L.

    2011-01-01

    This guide provides step-by-step guidance on the use of the SPAR-H method for quantifying Human Failure Events (HFEs). This guide is intended to be used with the worksheets provided in: 'The SPAR-H Human Reliability Analysis Method,' NUREG/CR-6883, dated August 2005. Each step in the process of producing a Human Error Probability (HEP) is discussed. These steps are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff. The discussions on dependence are extensive and include an appendix that describes insights obtained from the psychology literature.

  18. Two-step estimation for inhomogeneous spatial point processes

    DEFF Research Database (Denmark)

    Waagepetersen, Rasmus; Guan, Yongtao

    2009-01-01

    The paper is concerned with parameter estimation for inhomogeneous spatial point processes with a regression model for the intensity function and tractable second-order properties (K-function). Regression parameters are estimated by using a Poisson likelihood score estimating function and in the ...... and in the second step minimum contrast estimation is applied for the residual clustering parameters. Asymptotic normality of parameter estimates is established under certain mixing conditions and we exemplify how the results may be applied in ecological studies of rainforests....

  19. Global thermo-mechanical effects from a KBS-3 type repository

    International Nuclear Information System (INIS)

    Hakami, E.; Olofsson, Stig-Olof

    1998-01-01

    The objective of this study has been to identify the global thermo-mechanical effects in the bedrock hosting a nuclear waste repository. Numerical thermo-mechanical modeling using distinct element models was performed. The number of fracture zones, the heat intensity of the waste, the material properties of the rock mass and the boundary conditions of the models were varied. Different models for multi-level repositories were also analyzed and compared to the main single-level case. Further, the global influence from the excavation of repository tunnels and deposition holes was examined by introducing weaker rock mass material properties in the repository region of one model. The maximum compression stress obtained for the main model is 44 MPa and occurs at the repository level after about 100 years of deposition. Due to thermal expansion, the rock mass displaces upward, and the maximum heave at the ground surface after 1000 years is calculated to be 16 cm. In the area close to the ground surface the horizontal stresses reduce, causing the rock to yield in tension down to a depth of about 80 meters. The fracture zones show opening displacements at shallow depths and closing and shearing at the repository level. The maximum displacements are 0.3-2.5 cm for closing, 0.0-0.8 cm for opening and 0.2-2.2 cm for shearing. The resultant stresses and displacements depend in large part on the assumptions made concerning the heat intensity of the waste. In the main model, an initial heat intensity of 10 W/m 2 is assumed, which gives larger effects than the case with 6 W/m 2 . Another important input parameter for the analysis is the Young's modulus of the rock mass. In the main model, a value of 30 GPa is assumed. Higher values of Young's modulus give larger thermo-mechanical effects. All multi-level repository layouts give rise to higher temperatures than the single-level layout, causing the compressive stresses to increase more at the repository level. The multi

  20. Exact solution for stresses/displacements in a multilayered hollow cylinder under thermo-mechanical loading

    International Nuclear Information System (INIS)

    Yeo, W.H.; Purbolaksono, J.; Aliabadi, M.H.; Ramesh, S.; Liew, H.L.

    2017-01-01

    In this study, a new analytical solution by the recursive method for evaluating stresses/displacements in multilayered hollow cylinder under thermo-mechanical loading was developed. The results for temperature distribution, displacements and stresses obtained by using the proposed solution were shown to be in good agreement with the FEM results. The proposed analytical solution was also found to produce more accurate results than those by the analytical solution reported in literature. - Highlights: • A new analytical solution for evaluating stresses in multilayered hollow cylinder under thermo-mechanical loading. • A simple computational procedure using a recursive method. • A promising technique for evaluating the operating axial and hoop stresses in pressurized composite vessels.

  1. Effect of thermomechanical treatments on phase distribution and microstructure evolution of a Ti-48Al-2Mn-2Nb alloy

    International Nuclear Information System (INIS)

    Morris, M.A.; Leboeuf, M.

    1995-01-01

    Titanium aluminide alloys based on TiAl offer potential benefits as intermetallics for structural applications due to their low density and attractive properties at high temperature. However, their strength and ductility are very dependent on microstructural morphologies and much research is being devoted to obtaining optimal properties. The large grain sizes and solute segregations associated with conventional castings have forced much of the work to be focused on obtaining finer microstructures, both in terms of grain sizes as well as lamellar spacings. Thermomechanical treatments have been used to produce a large variety of structural morphologies ranging from fully lamellar to duplex and equiaxed and in which the proportion of each phase is also variable. By choosing the correct temperature and strain rate parameters, it may be possible to modify the microstructure by dynamic recrystallization, if during the mechanical process the lamellae of the α 2 phase can be broken down and be used to accelerate the kinetics of nucleation of the new γ grains. The present study has been carried out in order to examine this process and the authors have compared the different refined microstructures that can be obtained by a new thermomechanical process (ELIT pack-rolling) of a Ti-48Al-2Mn-2Nb alloy with respect to those obtained by heat treatments only

  2. SIMULTANEOUS MECHANICAL AND HEAT ACTIVATION: A NEW ROUTE TO ENHANCE SERPENTINE CARBONATION REACTIVITY AND LOWER CO2 MINERAL SEQUESTRATION PROCESS COST

    Energy Technology Data Exchange (ETDEWEB)

    M.J. McKelvy; J. Diefenbacher; R. Nunez; R.W. Carpenter; A.V.G. Chizmeshya

    2005-01-01

    Coal can support a large fraction of global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other candidate technologies, which propose long-term storage (e.g., ocean and geological sequestration), mineral sequestration permanently disposes of CO{sub 2} as geologically stable mineral carbonates. Only benign, naturally occurring materials are formed, eliminating long-term storage and liability issues. Serpentine carbonation is a leading mineral sequestration process candidate, which offers large scale, permanent sequestration. Deposits exceed those needed to carbonate all the CO{sub 2} that could be generated from global coal reserves, and mining and milling costs are reasonable ({approx}$4 to $5/ton). Carbonation is exothermic, providing exciting low-cost process potential. The remaining goal is to develop an economically viable process. An essential step in this development is increasing the carbonation reaction rate and degree of completion, without substantially impacting other process costs. Recently, the Albany Research Center (ARC) has accelerated serpentine carbonation, which occurs naturally over geological time, to near completion in less than an hour. While reaction rates for natural serpentine have been found to be too slow for practical application, both heat and mechanical (attrition grinding) pretreatment were found to substantially enhance carbonation reactivity. Unfortunately, these processes are too energy intensive to be cost-effective in their present form. In this project we explored the potential that utilizing power plant waste heat (e.g., available up to {approx}200-250 C) during mechanical activation (i.e., thermomechanical activation) offers to enhance serpentine mineral carbonation, while reducing pretreatment energy consumption and process cost. This project was carried out in collaboration with the Albany Research Center (ARC) to maximize the insight into the

  3. Manufacturing and thermomechanical testing of actively cooled all beryllium high heat flux test pieces

    International Nuclear Information System (INIS)

    Vasiliev, N.N.; Sokolov, Yu.A.; Shatalov, G.E.

    1995-01-01

    One of the problems affiliated to ITER high heat flux elements development is a problem of interface of beryllium protection with heat sink routinely made of copper alloys. To get rid of this problem all beryllium elements could be used as heat receivers in places of enhanced thermal loads. In accordance with this objectives four beryllium test pieces of two types have been manufactured in open-quotes Institute of Berylliumclose quotes for succeeding thermomechanical testing. Two of them were manufactured in accordance with JET team design; they are round open-quotes hypervapotron typeclose quotes test pieces. Another two ones are rectangular test sections with a twisted tape installed inside of the circular channel. Preliminary stress-strain analysis have been performed for both type of the test pieces. Hypervapotrons have been shipped to JET where they were tested on JET test bed. Thermomechanical testing of pieces of the type of open-quotes swirl tape inside of tubeclose quotes have been performed on Kurchatov Institute test bed. Chosen beryllium grade properties, some details of manufacturing, results of preliminary stress-strain analysis and thermomechanical testing of the test pieces open-quotes swirl tape inside of tubeclose quotes type are given in this report

  4. Drift-scale thermomechanical analysis for the retrievability systems study

    International Nuclear Information System (INIS)

    Tsai, F.C.

    1996-01-01

    A numerical method was used to estimate the stability of potential emplacement drifts without considering a ground support system as a part of the Thermal Loading Systems Study for the Yucca Mountain Site Characterization Project. The stability of the drift is evaluated with two variables: the level of thermal loading and the diameter of the emplacement drift. The analyses include the thermomechanical effects generated by the excavation of the drift, subsequently by the thermal loads from heat-emitting waste packages, and finally by the thermal reduction resulting from rapid cooling ventilation required for the waste retrieval if required. The Discontinuous Deformation Analysis (DDA) code was used to analyze the thermomechanical response of the rock mass of multiple blocks separated by joints. The result of this stability analysis is used to discuss the geomechanical considerations for the advanced conceptual design (ACD) with respect to retrievability. In particular, based on the rock mass strength of the host rock described in the current version of the Reference Information Base, the computed thermal stresses, generated by 111 MTU/acre thermal loads in the near field at 100 years after waste emplacement, is beyond the criterion for the rock mass strength used to predict the stability of the rock mass surrounding the emplacement drift

  5. Thermo-mechanical treatment for improvement of superplasticity of SUS304; SUS304 no chososei kyodo kaizen no tame no kako netsu shori

    Energy Technology Data Exchange (ETDEWEB)

    Kato, M.; Torisaka, Y. [Mechanical Engineering Lab., Tokyo (Japan)

    1998-01-25

    Thermo-mechanical treatment was given to improve further the superplastic behavior of SUS 304 stainless steel. In the SUS 304, martensite phase produced by the processing induced transformation may be reversely transformed to the primary austenite phase by high-temperature heating. Crystal grain size is micronized to 1 {mu} m by combining this reverse transformation and recrystallization of the austenite phase. However, the straining rate at that time is as extremely low as 1 times 10 {sup -4}/s or lower, which is insufficient for an industrial material. Therefore, the SUS 304 processed as described above was given again a series of thermo-mechanical treatment of the similar forced cold processing and annealing to ultra-micronize the crystalline particles. Majority of the crystalline particles have come to have a grain size of several hundred nm. This test piece showed a total elongation of 400% or more at a test temperature of 973 K and a straining rate of 1.8 times 10 {sup -3}/s or lower. In addition, the straining rate sensitivity index `m` at that time was 0.45 or higher. The superplastic deformation of the SUS 304 has a high possibility of being governed by dynamic recrystallization. 4 refs., 7 figs., 1 tab.

  6. Study of the Thermo-Mechanical Behavior of the CLIC Two-Beam Modules

    CERN Document Server

    Rossi, F; Riddone, G; Österberg, K; Kossyvakis, I; Gudkov, D; Samochkine, A

    2013-01-01

    The final luminosity target of the Compact LInear Collider (CLIC) imposes a micron-level stability requirement on the two-meter repetitive two-beam modules constituting the main linacs. Two-beam prototype modules are being assembled to extensively study their thermo-mechanical behaviour under different operation modes. The power dissipation occurring in the modules will be reproduced and the efficiency of the corresponding cooling systems validated. At the same time, the real environmental conditions present in the CLIC tunnel will be studied. Air conditioning and ventilation systems have been installed in the dedicated laboratory. The air temperature will be changed from 20 to 40°C, while the air flow rate will be varied up to 0.8 m/s. During all experimental tests, the alignment of the RF structures will be monitored to investigate the influence of power dissipation and air temperature on the overall thermo-mechanical behaviour. \

  7. A ten-step process to develop case management plans.

    Science.gov (United States)

    Tahan, Hussein A

    2002-01-01

    The use of case management plans has contained cost and improved quality of care successfully. However, the process of developing these plans remains a great challenge for healthcare executives, in this article, the author presents the answer to this challenge by discussing a 10-step formal process that administrators of patient care services and case managers can adapt to their institutions. It also can be used by interdisciplinary team members as a practical guide to develop a specific case management plan. This process is applicable to any care setting (acute, ambulatory, long term, and home care), diagnosis, or procedure. It is particularly important for those organizations that currently do not have a deliberate and systematic process to develop case management plans and are struggling with how to improve the efficiency and productivity of interdisciplinary teams charged with developing case management plans.

  8. A simple 1D model with thermomechanical coupling for superelastic SMAs

    International Nuclear Information System (INIS)

    Zaki, W; Morin, C; Moumni, Z

    2010-01-01

    This paper presents an outline for a new uniaxial model for shape memory alloys that accounts for thermomechanical coupling. The coupling provides an explanation of the dependence of SMA behavior on the loading rate. 1D simulations are carried in Matlab using simple finite-difference discretization of the mechanical and thermal equations.

  9. Thermomechanical fatigue of Sn-37 wt.% Pb model solder joints

    International Nuclear Information System (INIS)

    Liu, X.W.; Plumbridge, W.J.

    2003-01-01

    The fatigue of Sn-37 wt.% Pb model solder joints has been investigated under thermomechanical and thermal cycling. Based upon an analysis of displacements during thermomechancial cycling, a model solder joint has been designed to simulate actual joints in electronic packages. The strain-stress relationship, characterised by hysteresis loops, was determined during cycling from 30 to 125 deg. C, and the stress-range monitored throughout. The number of cycles to failure, as defined by the fall in stress range, was correlated to strain range and strain energy. The strain hardening exponent, k, varied with the definition of failure and, when a stress-range drop of 50% was used, it was 0.46. Cracks were produced during pure thermal cycling without external strains applied. These arose due to the local strains caused by thermal expansion mismatches between the solder and Cu 6 Sn 5 intermetallic layer, between the phases of solder, and due to the anisotropy of the materials. The fatigue life under thermomechanical cycling was significantly inferior to that obtained in isothermal mechanical cycling. A factor contributing to this inferiority is the internal damage produced during temperature cycling

  10. Influence of isothermal thermomechanical treatment on structure and properties of structural steels

    International Nuclear Information System (INIS)

    Smirnov, M.A.; Kaletin, A.Yu.; Schastlivthev, V.M.; Kaletina, Yu.V.

    1997-01-01

    A study is made into the structure and mechanical properties of steel 35KhGSA and 37KhN3A after isothermal hardening resulting in bainitic structure formation as well as after low-temperature thermomechanical treatment (LTTMT) combining the plastic deformation at the temperature of bainitic transformation and subsequent isothermal hardening. It is shown that LTTMT permits and essential enhancement of strength properties in steel 35KhGSA, high plasticity and impact strength being reserved. This is associated with bainitic structure refinement. In steel 37KhN3A the process of carbide formation takes place along with bainitic transformation, and LTTMT results in lesser strengthening. LTTMT is fount to not practically affect the tendency of structural steels to bainitic brittleness. This treatment promotes some shift of brittleness manifestation to lower temperatures

  11. Solvability of an unsaturated porous media flow problem with thermomechanical interaction

    Czech Academy of Sciences Publication Activity Database

    Detmann, B.; Krejčí, Pavel; Rocca, E.

    2016-01-01

    Roč. 48, č. 6 (2016), s. 4175-4201 ISSN 0036-1410 R&D Projects: GA ČR(CZ) GA15-12227S Institutional support: RVO:67985840 Keywords : porous media * hysteresis * thermomechanical interactions Subject RIV: BA - General Mathematics Impact factor: 1.648, year: 2016 http://epubs.siam.org/doi/abs/10.1137/16M1056365

  12. One-step process of hydrothermal and alkaline treatment of wheat straw for improving the enzymatic saccharification.

    Science.gov (United States)

    Sun, Shaolong; Zhang, Lidan; Liu, Fang; Fan, Xiaolin; Sun, Run-Cang

    2018-01-01

    To increase the production of bioethanol, a two-step process based on hydrothermal and dilute alkaline treatment was applied to reduce the natural resistance of biomass. However, the process required a large amount of water and a long operation time due to the solid/liquid separation before the alkaline treatment, which led to decrease the pure economic profit for production of bioethanol. Therefore, four one-step processes based on order of hydrothermal and alkaline treatment have been developed to enhance concentration of glucose of wheat straw by enzymatic saccharification. The aim of the present study was to systematically evaluated effect for different one-step processes by analyzing the physicochemical properties (composition, structural change, crystallinity, surface morphology, and BET surface area) and enzymatic saccharification of the treated substrates. In this study, hemicelluloses and lignins were removed from wheat straw and the morphologic structures were destroyed to various extents during the four one-step processes, which were favorable for cellulase absorption on cellulose. A positive correlation was also observed between the crystallinity and enzymatic saccharification rate of the substrate under the conditions given. The surface area of the substrate was positively related to the concentration of glucose in this study. As compared to the control (3.0 g/L) and treated substrates (11.2-14.6 g/L) obtained by the other three one-step processes, the substrate treated by one-step process based on successively hydrothermal and alkaline treatment had a maximum glucose concentration of 18.6 g/L, which was due to the high cellulose concentration and surface area for the substrate, accompanying with removal of large amounts of lignins and hemicelluloses. The present study demonstrated that the order of hydrothermal and alkaline treatment had significant effects on the physicochemical properties and enzymatic saccharification of wheat straw. The one-step

  13. SPAR-H Step-by-Step Guidance

    Energy Technology Data Exchange (ETDEWEB)

    April M. Whaley; Dana L. Kelly; Ronald L. Boring; William J. Galyean

    2012-06-01

    Step-by-step guidance was developed recently at Idaho National Laboratory for the US Nuclear Regulatory Commission on the use of the Standardized Plant Analysis Risk-Human Reliability Analysis (SPAR-H) method for quantifying Human Failure Events (HFEs). This work was done to address SPAR-H user needs, specifically requests for additional guidance on the proper application of various aspects of the methodology. This paper overviews the steps of the SPAR-H analysis process and highlights some of the most important insights gained during the development of the step-by-step directions. This supplemental guidance for analysts is applicable when plant-specific information is available, and goes beyond the general guidance provided in existing SPAR-H documentation. The steps highlighted in this paper are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff.

  14. Damage mechanisms in PBT-GF30 under thermo-mechanical cyclic loading

    International Nuclear Information System (INIS)

    Schaaf, A.; De Monte, M.; Hoffmann, C.; Vormwald, M.; Quaresimin, M.

    2014-01-01

    The scope of this paper is the investigation of damage mechanisms at microscopic scale on a short glass fiber reinforced polybutylene terephthalate (PBT-GF30) under thermo-mechanical cyclic loading. In addition the principal mechanisms are verified through micro mechanical FE models. In order to investigate the fatigue behavior of the material both isothermal strain controlled fatigue (ISCF) tests at three different temperatures and thermo-mechanical fatigue (TMF) tests were conducted on plain and notched specimens, manufactured by injection molding. The goal of the work is to determine the damage mechanisms occurring under TMF conditions and to compare them with the mechanisms occurring under ISCF. For this reason fracture surfaces of TMF and ISCF samples loaded at different temperature levels were analyzed using scanning electron microscopy. Furthermore, specimens that failed under TMF were examined on microsections revealing insight into both crack initiation and crack propagation. The findings of this investigation give valuable information about the main damage mechanisms of PBT-GF30 under TMF loading and serve as basis for the development of a TMF life estimation methodology

  15. Friction stir processing: a new grain refinement technique to achieve high strain rate superplasticity in commercial alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, R.S. [Missouri Univ., Rolla, MO (United States). Dept. of Metallurgical Engineering; Mahoney, M.W. [Rockwell International Corp., Thousand Oaks, CA (United States). Science Center

    2001-07-01

    Friction stir processing is a new thermo-mechanical processing technique that leads to a microstructure amenable for high strain rate superplasticity in commercial aluminum alloys. Friction stirring produces a combination of very fine grain size and high grain boundary misorientation angles. Preliminary results on a 7075 Al demonstrate high strain rate superplasticity in the temperature range of 430-510 C. For example, an elongation of >1000% was observed at 490 C and 1 x 10{sup -2} s{sup -1}. This demonstrates a new possibility to economically obtain a superplastic microstructure in commercial aluminum alloys. Based on these results, a three-step manufacturing process to fabricate complex shaped components can be envisaged: cast sheet or hot-pressed powder metallurgy sheet + friction stir processing + superplastic forging or forming. (orig.)

  16. Study of cast and thermo-mechanically strengthened chromium-nickel nitrogen-containing steel

    International Nuclear Information System (INIS)

    Prokoshkina, V.G.; Kaputkina, L.M.; Svyazhin, A.G.

    2000-01-01

    The effect of nitrogen on the structure and strength of corrosion-resistant chromium-nickel steels after thermal and thermomechanical treatment is studied. The 06Kh15N7AD and 07Kh15N7DAMB steels alloying by nitrogen was accomplished through the basic composition steels remelting in the molecular nitrogen atmosphere under the pressure of 0.1-2.5 MPa. The 02Kh15N5DAF and 05Kh15N5DAM steels ingots were obtained through melting in a plasma furnace under the nitrogen pressure of 0.4MPA. The high-temperature thermomechanical treatment (HTMT) was performed by rolling with preliminary blanks heating up to 1050 deg C and the rolling end temperature not below 950 deg C. It is shown, that the HTMT of the nitrogen-containing steels makes it possible to obtain strength characteristics by 1.5 times exceeding the properties of traditionally applicable corrosion-resistant steels, whereby sufficiently high plasticity of the nitrogen-containing steel is retained [ru

  17. Thermo-mechanical design of the SINGAP accelerator grids for ITER NB injectors

    Energy Technology Data Exchange (ETDEWEB)

    Agostinetti, P. [Consorzio RFX, Euratom-ENEA Association, Corso Stati Uniti 4, I35127 Padova (Italy)], E-mail: piero.agostinetti@igi.cnr.it; Dal Bello, S.; Dalla Palma, M.; Zaccaria, P. [Consorzio RFX, Euratom-ENEA Association, Corso Stati Uniti 4, I35127 Padova (Italy)

    2007-10-15

    The SINGle Aperture-SINgle GAP (SINGAP) accelerator for ITER neutral beam injector foresees four grids for the extraction and acceleration of negative ions, instead of the seven grids of the Multi-Aperture Multi-Grid (MAMuG) reference configuration. The grids have to fulfil specific requirements coming from ion extraction, beam optics and thermo-mechanical issues. This paper focuses on the thermo-hydraulic and thermo-mechanical design of the grids carried out by Consorzio RFX for the design of the first ITER NB injector and the ITER NB Test Facility. The cooling circuit design (position and shape of the channels) and the cooling parameters (water coolant temperatures, pressure and velocity) were optimized with sensitivity analyses in order to satisfy the grid functional requirements (temperatures, stresses, in plane and out of plane deformations). The design required a complete modelling of the grids and their support frames by means of 3D FE and CAD models.

  18. Thermo-mechanical design aspects of mercury bombardment ion thrusters.

    Science.gov (United States)

    Schnelker, D. E.; Kami, S.

    1972-01-01

    The mechanical design criteria are presented as background considerations for solving problems associated with the thermomechanical design of mercury ion bombardment thrusters. Various analytical procedures are used to aid in the development of thruster subassemblies and components in the fields of heat transfer, vibration, and stress analysis. Examples of these techniques which provide computer solutions to predict and control stress levels encountered during launch and operation of thruster systems are discussed. Computer models of specific examples are presented.

  19. Xylose Isomerization with Zeolites in a Two-Step Alcohol–Water Process

    DEFF Research Database (Denmark)

    Paniagua, Marta; Shunmugavel, Saravanamurugan; Melián Rodriguez, Mayra

    2015-01-01

    Isomerization of xylose to xylulose was efficiently catalyzed by large-pore zeolites in a two-step methanol–water process that enhanced the product yield significantly. The reaction pathway involves xylose isomerization to xylulose, which, in part, subsequently reacts with methanol to form methyl...

  20. Thermo-mechanical design of the SINGAP accelerator grids for ITER NB Injectors

    International Nuclear Information System (INIS)

    Agostinetti, P.; Dal Bello, S.; Palma, M.D.; Zaccaria, P.

    2006-01-01

    The SINGle Aperture - SINgle GAP (SINGAP) accelerator for ITER neutral beam injector foresees four grids for the extraction and acceleration of negative ions, instead of the seven grids of the Multi Aperture Multi Grid (MAMuG) reference configuration. Optimized geometry of the SINGAP grids (plasma, extraction, pre-acceleration, and grounded grid) was identified by CEA Association considering specific requirements for ions extraction and beam generation referring to experimental data and code simulations. This paper focuses on the thermo-hydraulic and thermo-mechanical design of the grids carried out by Consorzio RFX for the design of the first ITER NB Injector and the ITER NB Test Facility. The cooling circuit design (position and shape of the channels) and the cooling parameters (water coolant temperatures, pressure and velocity) were optimized with thermo-hydraulic and thermo-mechanical sensitivity analyses in order to satisfy the grid functional requirements (temperatures, in plane and out of plane deformations). A complete and detailed thermo-structural design assessment of the SINGAP grids was accomplished applying the structural design rules for ITER in-vessel components and considering both the reference load conditions and the maximum load provided by the power supplies. The design required a complete modelling of the grids and their support frames by means of 3D FE and CAD models. The grids were finally integrated with the support and cooling systems inside the beam source vessel. The main results of the thermo-hydraulic and thermo-mechanical analyses are presented. The open issues are then reported, mainly regarding the material properties characterization (static and fatigue tests) and the qualification of technologies for OFHC copper electro-deposition, brazing, and welding of heterogeneous materials. (author)

  1. Integrating social media and social marketing: a four-step process.

    Science.gov (United States)

    Thackeray, Rosemary; Neiger, Brad L; Keller, Heidi

    2012-03-01

    Social media is a group of Internet-based applications that allows individuals to create, collaborate, and share content with one another. Practitioners can realize social media's untapped potential by incorporating it as part of the larger social marketing strategy, beyond promotion. Social media, if used correctly, may help organizations increase their capacity for putting the consumer at the center of the social marketing process. The purpose of this article is to provide a template for strategic thinking to successfully include social media as part of the social marketing strategy by using a four-step process.

  2. Nuclear, thermo-mechanical and tritium release analysis of ITER breeding blanket

    International Nuclear Information System (INIS)

    Kosaku, Yasuo; Kuroda, Toshimasa; Enoeda, Mikio; Hatano, Toshihisa; Sato, Satoshi; Miki, Nobuharu; Akiba, Masato

    2003-06-01

    The design of the breeding blanket in ITER applies pebble bed breeder in tube (BIT) surrounded by multiplier pebble bed. It is assumed to use the same module support mechanism and coolant manifolds and coolant system as the shielding blankets. This work focuses on the verification of the design of the breeding blanket, from the viewpoints which is especially unique to the pebble bed type breeding blanket, such as, tritium breeding performance, tritium inventory and release behavior and thermo-mechanical performance of the ITER breeding blanket. With respect to the neutronics analysis, the detailed analyses of the distribution of the nuclear heating rate and TBR have been performed in 2D model using MCNP to clarify the input data for the tritium inventory and release rate analyses and thermo-mechanical analyses. With respect to the tritium inventory and release behavior analysis, the parametric analyses for selection of purge gas flow rate were carried out from the view point of pressure drop and the tritium inventory/release performance for Li 2 TiO 3 breeder. The analysis result concluded that purge gas flow rate can be set to conventional flow rate setting (88 l/min per module) to 1/10 of that to save the purge gas flow and minimize the size of purge gas pipe. However, it is necessary to note that more tritium is transformed to HTO (chemical form of water) in case of Li 2 TiO 3 compared to other breeder materials. With respect to the thermo-mechanical analyses of the pebble bed blanket structure, the analyses have been performed by ABAQUS with 2D model derived from one of eight facets of a blanket module, based on the reference design. Analyses were performed to identify the temperature distribution incorporating the pebble bed mechanical simulation and influence of mechanical behavior to the thermal behavior. The result showed that the maximum temperature in the breeding material was 617degC in the first row of breeding rods and the minimum temperature was 328

  3. Is it Feasible to Use Students' Self-reported Step Data in a Local School Policy Process?

    DEFF Research Database (Denmark)

    Bonde, Ane Høstgaard; Bruselius-Jensen, Maria

    2017-01-01

    Objective: We examined students’ self-reported step data and discussed the feasibility of using these data in a local school policy process. Methods: For 5 days during school hours, 281 stu- dents from grades 5–7 participating in a health education program, measured their steps using a pedometer......: Student-collected data showed similar patterns as reported in the literature, and therefore, a feasible perspective could be to use students’ self-reported step data in a local school policy process....

  4. Thermo-mechanical Modelling of Pebble Beds in Fusion Blankets and its Implementation by a Return-Mapping Algorithm

    International Nuclear Information System (INIS)

    Gan, Yixiang; Kamlah, Marc

    2008-01-01

    In this investigation, a thermo-mechanical model of pebble beds is adopted and developed based on experiments by Dr. Reimann at Forschungszentrum Karlsruhe (FZK). The framework of the present material model is composed of a non-linear elastic law, the Drucker-Prager-Cap theory, and a modified creep law. Furthermore, the volumetric inelastic strain dependent thermal conductivity of beryllium pebble beds is taken into account and full thermo-mechanical coupling is considered. Investigation showed that the Drucker-Prager-Cap model implemented in ABAQUS can not fulfill the requirements of both the prediction of large creep strains and the hardening behaviour caused by creep, which are of importance with respect to the application of pebble beds in fusion blankets. Therefore, UMAT (user defined material's mechanical behaviour) and UMATHT (user defined material's thermal behaviour) routines are used to re-implement the present thermo-mechanical model in ABAQUS. An elastic predictor radial return mapping algorithm is used to solve the non-associated plasticity iteratively, and a proper tangent stiffness matrix is obtained for cost-efficiency in the calculation. An explicit creep mechanism is adopted for the prediction of time-dependent behaviour in order to represent large creep strains in high temperature. Finally, the thermo-mechanical interactions are implemented in a UMATHT routine for the coupled analysis. The oedometric compression tests and creep tests of pebble beds at different temperatures are simulated with the help of the present UMAT and UMATHT routines, and the comparison between the simulation and the experiments is made. (authors)

  5. A Multi-objective Optimization Application in Friction Stir Welding: Considering Thermo-mechanical Aspects

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Hattel, Jesper Henri

    2010-01-01

    speed and traverse welding speed have been sought in order to achieve the goals mentioned above using an evolutionary multi-objective optimization (MOO) algorithm, i.e. non-dominated sorting genetic algorithm (NSGA-II), integrated with a transient, 2-dimensional sequentially coupled thermomechanical...

  6. Modelling thermomechanical conditions at the tool/matrix interface in Friction Stir Welding

    DEFF Research Database (Denmark)

    Schmidt, Henrik Nikolaj Blich; Hattel, Jesper

    2004-01-01

    is obtained. A fully coupled thermo-mechanical 3D FE model has been developed in ABAQUS/Explicit using the ALE formulation and the Johnson-Cook material law. The contact forces are modelled by Coulomb’s law of friction making the contact condition highly solution dependent. The heat is generated by both...

  7. An approach to eliminate stepped features in multistage incremental sheet forming process: Experimental and FEA analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nirala, Harish Kumar; Jain, Prashant K.; Tandon, Puneet [PDPM Indian Institute of Information Technology, Design and Manufacturing Jabalpur Jabalpur-482005, Madhya Pradesh (India); Roy, J. J.; Samal, M. K. [Bhabha Atomic Research Centre, Mumbai (India)

    2017-02-15

    Incremental sheet forming (ISF) is a recently developed manufacturing technique. In ISF, forming is done by applying deformation force through the motion of Numerically controlled (NC) single point forming tool on the clamped sheet metal blank. Single Point Incremental sheet forming (SPISF) is also known as a die-less forming process because no die is required to fabricate any component by using this process. Now a day it is widely accepted for rapid manufacturing of sheet metal components. The formability of SPISF process improves by adding some intermediate stages into it, which is known as Multi-stage SPISF (MSPISF) process. However during forming in MSPISF process because of intermediate stages stepped features are generated. This paper investigates the generation of stepped features with simulation and experimental results. An effective MSPISF strategy is proposed to remove or eliminate this generated undesirable stepped features.

  8. Thermomechanical Behavior of Rotor with Rubbing

    Directory of Open Access Journals (Sweden)

    Jerzy T. Sawicki

    2003-01-01

    Full Text Available This article presents an analytical study of the dynamics and stability of rotors subjected to rubbing due to contact with seals, taking account of associated thermal effects. The seal interaction force acting on the shaft gives rise to a friction force, which is a source of heating and can induce so-called spiral vibrations. A mathematical model that has been developed couples the heat-conduction equation with the equations for motion of the rotor. Numerical simulations have been conducted that show the thermomechanical behavior of the rotor at various operating conditions. A procedure for analyzing the stability of multibearing rotors based on the system eigenvalue analysis and the state-space approach has been proposed. Finally, the experimental data related to full annular rub have been presented.

  9. 3-D electromagnetic and thermo-mechanical simulation of a RF cavity

    CERN Document Server

    Launay, F

    2003-01-01

    A 3-D thermo-mechanical study of the edge of entrance blade of IPHI's RFQ was conducted by means of I-DEAS code. The aim is to compare the temperatures reached, the constraints, and the deformations calculated on the basis of RF power density stored on the blade obtained by means of two different electromagnetic computational codes, SOPRANO and MAFIA.

  10. New Nomenclatures for Heat Treatments of Additively Manufactured Titanium Alloys

    Science.gov (United States)

    Baker, Andrew H.; Collins, Peter C.; Williams, James C.

    2017-07-01

    The heat-treatment designations and microstructure nomenclatures for many structural metallic alloys were established for traditional metals processing, such as casting, hot rolling or forging. These terms do not necessarily apply for additively manufactured (i.e., three-dimensionally printed or "3D printed") metallic structures. The heat-treatment terminology for titanium alloys generally implies the heat-treatment temperatures and their sequence relative to a thermomechanical processing step (e.g., forging, rolling). These designations include: β-processing, α + β-processing, β-annealing, duplex annealing and mill annealing. Owing to the absence of a thermomechanical processing step, these traditional designations can pose a problem when titanium alloys are first produced via additive manufacturing, and then heat-treated. This communication proposes new nomenclatures for heat treatments of additively manufactured titanium alloys, and uses the distinct microstructural features to provide a correlation between traditional nomenclature and the proposed nomenclature.

  11. Thermomechanical effects on permeability for a 3-D model of YM rock

    International Nuclear Information System (INIS)

    Berge, P A; Blair, S C; Wang, H F

    1999-01-01

    The authors estimate how thermomechanical processes affect the spatial variability of fracture permeability for a 3-D model representing Topopah Spring tuff at the nuclear-waste repository horizon in Yucca Mountain, Nevada. Using a finite-difference code, they compute thermal stress changes. They evaluate possible permeability enhancement resulting from shear slip along various mapped fracture sets after 50 years of heating, for rock in the near-field environment of the proposed repository. The results indicate permeability enhancement of a factor of 2 for regions about 10 to 30 m above drifts, for north-south striking vertical fractures. Shear slip and permeability increases of a factor of 4 can occur in regions just above drifts, for east-west striking vertical fractures. Information on how permeability may change over the lifetime of a geologic repository is important to the prediction and evaluation of repository performance

  12. Thermomechanical Behavior of High Performance Epoxy/Organoclay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Artur Soares Cavalcanti Leal

    2014-01-01

    Full Text Available Nanocomposites of epoxy resin containing bentonite clay were fabricated to evaluate the thermomechanical behavior during heating. The epoxy resin system studied was prepared using bifunctional diglycidyl ether of bisphenol A (DGEBA, crosslinking agent diaminodiphenylsulfone (DDS, and diethylenetriamine (DETA. The purified bentonite organoclay (APOC was used in all experiments. The formation of nanocomposite was confirmed by X-ray diffraction analysis. Specimens of the fabricated nanocomposites were characterized by dynamic mechanical analysis (DMA. According to the DMA results a significant increase in glass transition temperature and storage modulus was evidenced when 1 phr of clay is added to epoxy resin.

  13. Effects of acute alcohol intoxication on automated processing: evidence from the double-step paradigm.

    Science.gov (United States)

    Vorstius, Christian; Radach, Ralph; Lang, Alan R

    2012-02-01

    Reflexive and voluntary levels of processing have been studied extensively with respect to possible impairments due to alcohol intoxication. This study examined alcohol effects at the 'automated' level of processing essential to many complex visual processing tasks (e.g., reading, visual search) that involve ongoing modifications or reprogramming of well-practiced routines. Data from 30 participants (16 male) were collected in two counterbalanced sessions (alcohol vs. no-alcohol control; mean breath alcohol concentration = 68 mg/dL vs. 0 mg/dL). Eye movements were recorded during a double-step task where 75% of trials involved two target stimuli in rapid succession (inter-stimulus interval [ISI]=40, 70, or 100 ms) so that they could elicit two distinct saccades or eye movements (double steps). On 25% of trials a single target appeared. Results indicated that saccade latencies were longer under alcohol. In addition, the proportion of single-step responses and the mean saccade amplitude (length) of primary saccades decreased significantly with increasing ISI. The key novel finding, however, was that the reprogramming time needed to cancel the first saccade and adjust saccade amplitude was extended significantly by alcohol. The additional time made available by prolonged latencies due to alcohol was not utilized by the saccade programming system to decrease the number of two-step responses. These results represent the first demonstration of specific alcohol-induced programming deficits at the automated level of oculomotor processing.

  14. Improving the two-step remediation process for CCA-treated wood. Part I, Evaluating oxalic acid extraction

    Science.gov (United States)

    Carol Clausen

    2004-01-01

    In this study, three possible improvements to a remediation process for chromated-copper-arsenate (CCA) treated wood were evaluated. The process involves two steps: oxalic acid extraction of wood fiber followed by bacterial culture with Bacillus licheniformis CC01. The three potential improvements to the oxalic acid extraction step were (1) reusing oxalic acid for...

  15. Thermomechanical behavior of mica layers with lenticular fissures

    Science.gov (United States)

    Yang, Michael Xinyi

    The thermomechanical behavior of natural phlogopite mica specimens from seven different origins is characterized. An initial heat treatment, to a temperature between 300°C and 400°C, is found to form fissures that stabilize in the material. Following the initial heat treatment, all the phlogopite specimens, regardless of their origin and polytype, exhibit the extraordinarily large thermal expansion (intumescence), more than 200% at 600°C, in the direction perpendicular to the basal planes. This phenomenon is strictly reproducible when tested under a range of thermal conditions including thermal shock, multiple thermal fatigue cycles, varying heating or cooling rates and isothermal heating over an extensive period of time at different temperatures up to 585°C. The hysteresis, associated with the thermal cycle, is increased when the specimen is heated or cooled at a faster rate. The maximum coefficient of linear thermal expansion, approximately 10 -2°C-1, is observed over the temperature range 100--120°C. This is due to the non-structural water, entrapped within the layer structure, which undergoes a phase transition and causes the mica layers to expand abruptly. A model of lenticular fissures is developed based on thin-plate mechanics and thermodynamics assumptions. The state of a lenticular fissure with water vapor molecules is determined to correlate the experimental parameters with the material properties. The average density of water vapor molecules within a lenticular fissure is calculated to be ˜1025 m 3 for the temperature interval between 100°C and 275°C. The concentration of non-structure water, based on the model calculation, is less than 0.1% by weight. Acoustic emission (AE) signals have been reported by Pranevicius et al. (1995) to correspond to the microstructure changes as the internal lenticular fissures develop in phlogopite. This technique has also been proven feasible to characterize the thermomechanical behavior of other layer structures

  16. Low-temperature process steps for realization of non-volatile memory devices

    NARCIS (Netherlands)

    Brunets, I.; Boogaard, A.; Aarnink, Antonius A.I.; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.; Holleman, J.; Schmitz, Jurriaan

    2007-01-01

    In this work, the low-temperature process steps required for the realization of nano-crystal non-volatile memory cells are discussed. An amorphous silicon film, crystallized using a diode pumped solid state green laser irradiating at 532 nm, is proposed as an active layer. The deposition of the

  17. Equipment for the investigation of the thermomechanical fatigue of metallic materials

    International Nuclear Information System (INIS)

    Wolter, F.; Petersen, C.

    1992-01-01

    Within the framework of the European research program on nuclear fusion, a question is to be answered which is of great importance for the design of a fusion reactor, namely: To what extent is the 'First Wall structure' damaged by the pulsating mode of operation in this reactor type. This pulsating mode of operation leads to a thermal and mechanical cyclic stress in the metal support structure of the reactor. Thermomechanical cyclic stresses of a similar kind also occur in aircraft turbines, rocket drive units, and heat generating systems. For simulation of such stresses, a facility was developed in the Karlsruhe Nuclear Research Center which permits to produce thermomechanical cyclic stresses in uniaxial metallic materials specimens. The results of investigations with a martensitic 12%-Cr steel are explained. The stress range variations show a degressive behavior at the onset of fatigue and develop into a linear decline. The plastic strain reached a plateau after a number of cycles which was dependent on the mechanical strain (linear behavior). Relationships can be described by a simple transformation of number of cycles to failure between mechanical strain and number of stress cycles to failure. (orig./MM) [de

  18. One-step electrodeposition process of CuInSe2: Deposition time effect

    Indian Academy of Sciences (India)

    Administrator

    CuInSe2 thin films were prepared by one-step electrodeposition process using a simplified two- electrodes system. ... homojunctions or heterojunctions (Rincon et al 1983). Efficiency of ... deposition times onto indium thin oxide (ITO)-covered.

  19. Step-by-step cyclic processes scheduling

    DEFF Research Database (Denmark)

    Bocewicz, G.; Nielsen, Izabela Ewa; Banaszak, Z.

    2013-01-01

    Automated Guided Vehicles (AGVs) fleet scheduling is one of the big problems in Flexible Manufacturing System (FMS) control. The problem is more complicated when concurrent multi-product manufacturing and resource deadlock avoidance policies are considered. The objective of the research is to pro......Automated Guided Vehicles (AGVs) fleet scheduling is one of the big problems in Flexible Manufacturing System (FMS) control. The problem is more complicated when concurrent multi-product manufacturing and resource deadlock avoidance policies are considered. The objective of the research...... is to provide a declarative model enabling to state a constraint satisfaction problem aimed at AGVs fleet scheduling subject to assumed itineraries of concurrently manufactured product types. In other words, assuming a given layout of FMS’s material handling and production routes of simultaneously manufactured...... orders, the main objective is to provide the declarative framework aimed at conditions allowing one to calculate the AGVs fleet schedule in online mode. An illustrative example of the relevant algebra-like driven step-by-stem cyclic scheduling is provided....

  20. The Value of Step-by-Step Risk Assessment for Unmanned Aircraft

    DEFF Research Database (Denmark)

    La Cour-Harbo, Anders

    2018-01-01

    The new European legislation expected in 2018 or 2019 will introduce a step-by-step process for conducting risk assessments for unmanned aircraft flight operations. This is a relatively simple approach to a very complex challenge. This work compares this step-by-step process to high fidelity risk...... modeling, and shows that at least for a series of example flight missions there is reasonable agreement between the two very different methods....

  1. Modeling of the thermo-mechanical behaviour of the PWR fuel

    International Nuclear Information System (INIS)

    Mailhe, P.

    2014-01-01

    This article reviews the various physical phenomena that take place in an irradiated fuel rod and presents the development of the thermo-mechanical codes able to simulate them. Though technically simple the fuel rod is the place where appear 4 types of process: thermal, gas behaviour, mechanical and corrosion that combine involving 5 elements: the fuel pellet, the fuel clad, the fuel-clad gap, the inside volume and the coolant. For instance the pellet is the place where the following mechanical processes took place: thermal dilatation, elastic deformation, creep deformation, densification, solid swelling, gaseous swelling and cracking. The first industrial code simulating the behaviour of the fuel rod was COCCINEL, it was developed by AREVA teams from the American PAD code that was included in the Westinghouse license. Today the GALILEO code has replaced the COPERNIC code that was developed in the beginning of the 2000 years. GALILEO is a synthesis of the state of the art of the different models used in the codes validated for PWR and BWR. GALILEO has been validated on more than 1500 fuel rods concerning PWR, BWR and specific reactors like Siloe, Osiris, HFR, Halden, Studsvik, BR2/3,...) and also for extended burn-ups. (A.C.)

  2. Multiscale Thermo-Mechanical Design and Analysis of High Frequency and High Power Vacuum Electron Devices

    Science.gov (United States)

    Gamzina, Diana

    Diana Gamzina March 2016 Mechanical and Aerospace Engineering Multiscale Thermo-Mechanical Design and Analysis of High Frequency and High Power Vacuum Electron Devices Abstract A methodology for performing thermo-mechanical design and analysis of high frequency and high average power vacuum electron devices is presented. This methodology results in a "first-pass" engineering design directly ready for manufacturing. The methodology includes establishment of thermal and mechanical boundary conditions, evaluation of convective film heat transfer coefficients, identification of material options, evaluation of temperature and stress field distributions, assessment of microscale effects on the stress state of the material, and fatigue analysis. The feature size of vacuum electron devices operating in the high frequency regime of 100 GHz to 1 THz is comparable to the microstructure of the materials employed for their fabrication. As a result, the thermo-mechanical performance of a device is affected by the local material microstructure. Such multiscale effects on the stress state are considered in the range of scales from about 10 microns up to a few millimeters. The design and analysis methodology is demonstrated on three separate microwave devices: a 95 GHz 10 kW cw sheet beam klystron, a 263 GHz 50 W long pulse wide-bandwidth sheet beam travelling wave tube, and a 346 GHz 1 W cw backward wave oscillator.

  3. Implementation of Real-Time Machining Process Control Based on Fuzzy Logic in a New STEP-NC Compatible System

    Directory of Open Access Journals (Sweden)

    Po Hu

    2016-01-01

    Full Text Available Implementing real-time machining process control at shop floor has great significance on raising the efficiency and quality of product manufacturing. A framework and implementation methods of real-time machining process control based on STEP-NC are presented in this paper. Data model compatible with ISO 14649 standard is built to transfer high-level real-time machining process control information between CAPP systems and CNC systems, in which EXPRESS language is used to define new STEP-NC entities. Methods for implementing real-time machining process control at shop floor are studied and realized on an open STEP-NC controller, which is developed using object-oriented, multithread, and shared memory technologies conjunctively. Cutting force at specific direction of machining feature in side mill is chosen to be controlled object, and a fuzzy control algorithm with self-adjusting factor is designed and embedded in the software CNC kernel of STEP-NC controller. Experiments are carried out to verify the proposed framework, STEP-NC data model, and implementation methods for real-time machining process control. The results of experiments prove that real-time machining process control tasks can be interpreted and executed correctly by the STEP-NC controller at shop floor, in which actual cutting force is kept around ideal value, whether axial cutting depth changes suddenly or continuously.

  4. Pilot trials of hemicelluloses extraction prior to thermomechanical pulp production: Part 1

    Science.gov (United States)

    Carl Houtman; Eric Horn

    2011-01-01

    Pilot data indicate that wood chip pretreatment with oxalic acid reduced the specific energy required to make thermomechanical pulp. A combined oxalic acid/bisulfite treatment resulted in 21% refiner energy savings and 13% increase in brightness for aspen. A low level of oxalic acid treatment was effective for spruce. Energy savings of 30% was observed with no...

  5. Thermomechanical Analysis (TMA) and its application to polymer systems

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Jillian Cathleen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-25

    Thermomechanical analysis (TMA) instruments are used to measure dimensional changes as a sample is heated or cooled. Data obtained from these instruments can be used to calculate the glass transition (Tg) and the coefficient of thermal expansion (CTE). Commonly, materials expand when heated and contract when cooled; however, the rate of such changes depends largely on the type of material. In manufacturing, it is important to use components with similar CTE values to avoid product failure, leaks, or a build-up of thermal stress. Therefore, TMA is a straightforward, useful tool in research and industry.

  6. Contribution of Brazil nut shell fiber and electron-beam irradiation in thermomechanical properties of HDPE

    International Nuclear Information System (INIS)

    Polato, Pamella; Lorusso, Leandro Alex; Souza, Clecia de Moura; Moura, Esperidiana Augusta Barretos de; Chinellato, Anne; Rosa, Ricardo de

    2010-01-01

    In the present work, the influence of electron-beam irradiation on thermo-mechanical properties of HDPE and HDPE/Brazil nut shell fiber composite was investigated. The materials were irradiated at radiation dose 50 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated samples were submitted to thermo-mechanical tests and the correlation between their properties was discussed. The results showed that the incorporation of Brazil nut shell fiber represented a significant gain (p < 0,05) in tensile strength at break, flexural strength, flexural module, Vicat softening temperature and heat distortion temperature (HDT) properties of the HDPE. In addition, the irradiated HDPE/Brazil nut shell fiber composite presented a significant increase (p < 0.05) in this properties compared with irradiated HDPE. (author)

  7. Preliminary thermal/thermomechanical analyses of the Site Characterization Plan's Conceptual Design for a repository containing horizontally emplaced waste packages at the Deaf Smith County site

    International Nuclear Information System (INIS)

    Ghantous, N.Y.; Raines, G.E.

    1987-10-01

    This report presents thermal/thermomechanical analyses of the Site Characterization Plan Conceptual Design for horizontal package emplacement at the Deaf Smith County site, Texas. The repository was divided into three geometric regions. Then two-dimensional finite-element models were set up to approximate the three-dimensional nature of each region. Thermal and quasistatic thermomechanical finite-element analyses were performed to evaluate the thermal/thermomechanical responses of the three regions. The exponential-time creep law was used to represent the creep behavior of salt rock. The repository design was evaluated by comparing the thermal/thermomechanical responses obtained for the three regions with interim performance constraints. The preliminary results show that all the performance constraints are met except for those of the waste package. The following factors were considered in interpreting these results: (1) the qualitative description of the analytical responses; (2) the limitations of the analyses; and (3) either the conclusions based on overall evaluation of limitations and analytical results or the conclusions based on the fact that the repository design may be evaluated only after further analyses. Furthermore, a parametric analysis was performed to estimate the effect of material parameters on the predicted thermal/thermomechanical response. 23 refs., 34 figs., 9 tabs

  8. Simplified Modeling Strategy for the Thermomechanical Analysis of Massive Reinforced Concrete Structures at an Early Age

    Directory of Open Access Journals (Sweden)

    Jacky Mazars

    2018-03-01

    Full Text Available The objective of this work is to propose a comprehensive and efficient modeling approach to simulate the entire loading program of the RG8 test (both the restrained shrinkage and mechanical parts performed within the framework of the French national program CEOS.fr. This effort was made possible by introducing a multi-fiber beam discretization that included a thermomechanical model coupled with a unilateral concrete damage model. Due to the massiveness of the test structure, the scale effect needed to be taken into account. This step could be accomplished through use of a Weibull law. Extensive results were obtained during the experiment, some of which focused on deformations and forces developed in the structure by restrained shrinkage, the times of crack appearance and opening, and the consequences of damage sustained on the residual mechanical performance of the beam. A comparison with calculation output has demonstrated the ability of our modeling approach to simulate phenomena at both global and local levels, thus confirming the relevance of model choices made.

  9. Influence of compatibilizer on blends degradation during processing

    Directory of Open Access Journals (Sweden)

    Walter R. Waldman

    2013-01-01

    Full Text Available The thermomechanical degradation of blends made from polypropylene and polystyrene, with or without compatibilizer, was studied using an internal mixer coupled to a torque rheometer. The blends processed without compatibilizer presented regular and expected results regarding torque reduction, with evidence of chain scission. The blends processed with the block copolymer of styrene and butadiene, SBS, as a compatibilizer presented unchanged or less reduced variation on torque values during processing. The extraction of stabilizers from the compatibilizer before processing did not affect the results. The compatibilizer concentration in the blends was varied, with its influence still being observed in concentrations as low as 0.03 parts per hundred. Similar results were obtained in an experiment comparing the performance of a primary commercial anti-oxidant, Irganox 1076, and the compatibilizer SBS. Therefore, the compatibilizer can be considered as a processing aid agent with positive influence on avoiding thermomechanical degradation.

  10. Field theoretical approach to proton-nucleus reactions: II-Multiple-step excitation process

    International Nuclear Information System (INIS)

    Eiras, A.; Kodama, T.; Nemes, M.

    1989-01-01

    A field theoretical formulation to multiple step excitation process in proton-nucleus collision within the context of a relativistic eikonal approach is presented. A closed form expression for the double differential cross section can be obtained whose structure is very simple and makes the physics transparent. Glauber's formulation of the same process is obtained as a limit of ours and the necessary approximations are studied and discussed. (author) [pt

  11. Defining process design space for a hydrophobic interaction chromatography (HIC) purification step: application of quality by design (QbD) principles.

    Science.gov (United States)

    Jiang, Canping; Flansburg, Lisa; Ghose, Sanchayita; Jorjorian, Paul; Shukla, Abhinav A

    2010-12-15

    The concept of design space has been taking root under the quality by design paradigm as a foundation of in-process control strategies for biopharmaceutical manufacturing processes. This paper outlines the development of a design space for a hydrophobic interaction chromatography (HIC) process step. The design space included the impact of raw material lot-to-lot variability and variations in the feed stream from cell culture. A failure modes and effects analysis was employed as the basis for the process characterization exercise. During mapping of the process design space, the multi-dimensional combination of operational variables were studied to quantify the impact on process performance in terms of yield and product quality. Variability in resin hydrophobicity was found to have a significant influence on step yield and high-molecular weight aggregate clearance through the HIC step. A robust operating window was identified for this process step that enabled a higher step yield while ensuring acceptable product quality. © 2010 Wiley Periodicals, Inc.

  12. A First Step in Learning Analytics: Pre-Processing Low-Level Alice Logging Data of Middle School Students

    Science.gov (United States)

    Werner, Linda; McDowell, Charlie; Denner, Jill

    2013-01-01

    Educational data mining can miss or misidentify key findings about student learning without a transparent process of analyzing the data. This paper describes the first steps in the process of using low-level logging data to understand how middle school students used Alice, an initial programming environment. We describe the steps that were…

  13. Dynamic mechanical properties of hydroxyapatite/polyethylene oxide nanocomposites: characterizing isotropic and post-processing microstructures

    Science.gov (United States)

    Shofner, Meisha; Lee, Ji Hoon

    2012-02-01

    Compatible component interfaces in polymer nanocomposites can be used to facilitate a dispersed morphology and improved physical properties as has been shown extensively in experimental results concerning amorphous matrix nanocomposites. In this research, a block copolymer compatibilized interface is employed in a semi-crystalline matrix to prevent large scale nanoparticle clustering and enable microstructure construction with post-processing drawing. The specific materials used are hydroxyapatite nanoparticles coated with a polyethylene oxide-b-polymethacrylic acid block copolymer and a polyethylene oxide matrix. Two particle shapes are used: spherical and needle-shaped. Characterization of the dynamic mechanical properties indicated that the two nanoparticle systems provided similar levels of reinforcement to the matrix. For the needle-shaped nanoparticles, the post-processing step increased matrix crystallinity and changed the thermomechanical reinforcement trends. These results will be used to further refine the post-processing parameters to achieve a nanocomposite microstructure with triangulated arrays of nanoparticles.

  14. Thermo-mechanical behaviour during encapsulation of glass in a steel vessel

    International Nuclear Information System (INIS)

    Nakhodchi, S.; Smith, D.J.; Thomas, B.G.

    2016-01-01

    Quantitative numerical simulations and qualitative evaluations are conducted to elucidate thermo-mechanical behaviour during pouring and solidification of molten glass into a stainless-steel cylindrical container. Residual stress and structural integrity in this casting/vitrification process is important because it can be used for long-term storage of high-level nuclear wastes. The predicted temperature and stress distributions in the glass and container agree well with previous measurements of the temperature histories and residual stresses. Three different thermal-stress models are developed using the finite-element method and compared. Two simple slice models were developed based on the generalized plane strain assumption as well as a detailed two-dimensional axi-symmetric model that adds elements according to the stages of pouring glass into the stainless steel container. The results reveal that mechanical interaction between the glass and the wall of the stainless steel container generates residual tensile stresses that approach the yield strength of the steel. Together, these results reveal important insights into the mechanism of stress generation in the process, the structural integrity of the product, and accuracy of the modelling-tool predictions. - Highlights: • Source of residual stresses in glass and stainless steel containers (canisters) is discussed. • Final residual stresses in both glass and container is quantified. • Simple models presented for simulation of complicated casting process. • Comparison between detailed and simple FE modeling.

  15. Study of the thermo-mechanical performances of the IFMIF-EVEDA Lithium Test Loop target assembly

    Energy Technology Data Exchange (ETDEWEB)

    Di Maio, P.A., E-mail: dimaio@din.unipa.it [Dipartimento dell' Energia, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Arena, P.; Bongiovi, G. [Dipartimento dell' Energia, Universita di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Giammusso, R.; Micciche, G.; Tincani, A. [ENEA C. R. Brasimone, 40032 Camugnano, Bologna (Italy)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer IFMIF-EVEDA target assembly thermo-mechanical behavior has been investigated. Black-Right-Pointing-Pointer Finite element method has been followed and a commercial code has been used. Black-Right-Pointing-Pointer Nominal, design and pressure test steady state scenarios and start-up transient conditions have been investigated. Black-Right-Pointing-Pointer Steady state results have shown that back-plate yielding may occur only under the design scenario. Black-Right-Pointing-Pointer Transient analysis has indicated that TA start-up lasts for {approx}60 h. - Abstract: Within the framework of the IFMIF R and D program and in close cooperation with ENEA-Brasimone, at the Department of Energy of the University of Palermo a research campaign has been launched to investigate the thermo-mechanical behavior of the target assembly under both steady state and start-up transient conditions. A theoretical approach based on the finite element method (FEM) has been followed and a well-known commercial code has been adopted. A realistic 3D FEM model of the target assembly has been set-up and optimized by running a mesh independency analysis. A proper set of loads and boundary conditions, mainly concerned with radiation heat transfer between the target assembly external walls and the inner walls of its containment vessel, have been considered and the target assembly thermo-mechanical behavior under nominal, design and pressure test steady state scenarios and start-up transient conditions has been investigated. Results are herewith reported and discussed.

  16. Thermomechanical analysis of Natural Rubber behaviour stressed at room temperature.

    Directory of Open Access Journals (Sweden)

    Chrysochoos A.

    2010-06-01

    Full Text Available Owing to their high molecular mobility, stressed rubber chains can easily change their conformations and get orientated. This phenomena leads to so high reversible draw ratio that this behaviour is called rubber elasticity [1-3]. The analogy with ideal gases leads to an internal energy independent of elongation, the stress being attributed to a so-called configuration entropy. However, this analysis cannot take thermal expansion into account and moreover prohibits predicting standard thermo-elastic effect noticed at small elongations and the thermoelastic inversion effects [4]. This paper aims at : observing and quantifying dissipative and coupling effects associated with deformation energy, generated when Natural Rubber is stretched. re-examine the thermomechanical behaviour model of rubberlike materials, under the generalised standard material concept. From an experimental viewpoint, energy balance is created using infrared and quantitative imaging techniques. Digital Image Correlation (DIC provides in-the-plane displacement fields and, after derivation, strain and strain-rate fields. We have used those techniques to evidence the thermoelastic inversion effect as shown on Figure 1 where different weights have been fixed to warmed specimen and we monitored the sample deformation while it recovers room temperature. But we have also used those techniques to perform energy balance : analysis of the mechanical equilibrium allows estimates of the stress pattern and computation of deformation energy rates under a plane stress hypothesis [5]. Infrared Thermography (IRT gives the surface temperature of the sample. To estimate the distribution of heat sources, image processing with a local heat equation and a minimal set of approximation functions (image filtering was used. The time courses of deformation energy and heat associated with cyclic process are plotted in Figure 2. The time derivatives of both forms of energy are approximately similar. This

  17. Thermomechanical behaviour of bolted assemblies

    International Nuclear Information System (INIS)

    Scliffet, L.

    1995-01-01

    This paper presents first results obtained in an R and D study on the thermomechanical behaviour of bolted assemblies. Thermal shocks during operating transients both severely distort such assemblies and cause variations in stud pre-loads. So during a hot shock, the thermal gradient in the flange induced over-tightening due to the differential thermal expansion involved. Over-tightening can reach 70% of the nominal value, usually after 10 to 15 mn, after which the stress relaxes as soon as the heating affects the stud. A series of hot shocks causes assembly fatigue, notably resulting in thread plasticization, making it impossible to tighten the studs. In the case of cold transients, the reverse phenomenon is observed. The hot flange contracts sharply upon contact with the cold fluid, causing stress relief in the expanded studs. The resulting loss of tensile stress, which reaches up to 50%, can then cause severe leakage, especially if the nominal tightening capacity is already impaired. The study presented is based on tests and modelling. (author). 16 figs

  18. Atomistic modeling of thermomechanical properties of SWNT/Epoxy nanocomposites

    Science.gov (United States)

    Fasanella, Nicholas; Sundararaghavan, Veera

    2015-09-01

    Molecular dynamics simulations are performed to compute thermomechanical properties of cured epoxy resins reinforced with pristine and covalently functionalized carbon nanotubes. A DGEBA-DDS epoxy network was built using the ‘dendrimer’ growth approach where 75% of available epoxy sites were cross-linked. The epoxy model is verified through comparisons to experiments, and simulations are performed on nanotube reinforced cross-linked epoxy matrix using the CVFF force field in LAMMPS. Full stiffness matrices and linear coefficient of thermal expansion vectors are obtained for the nanocomposite. Large increases in stiffness and large decreases in thermal expansion were seen along the direction of the nanotube for both nanocomposite systems when compared to neat epoxy. The direction transverse to nanotube saw a 40% increase in stiffness due to covalent functionalization over neat epoxy at 1 K whereas the pristine nanotube system only saw a 7% increase due to van der Waals effects. The functionalized SWNT/epoxy nanocomposite showed an additional 42% decrease in thermal expansion along the nanotube direction when compared to the pristine SWNT/epoxy nanocomposite. The stiffness matrices are rotated over every possible orientation to simulate the effects of an isotropic system of randomly oriented nanotubes in the epoxy. The randomly oriented covalently functionalized SWNT/Epoxy nanocomposites showed substantial improvements over the plain epoxy in terms of higher stiffness (200% increase) and lower thermal expansion (32% reduction). Through MD simulations, we develop means to build simulation cells, perform annealing to reach correct densities, compute thermomechanical properties and compare with experiments.

  19. Atomistic modeling of thermomechanical properties of SWNT/Epoxy nanocomposites

    International Nuclear Information System (INIS)

    Fasanella, Nicholas; Sundararaghavan, Veera

    2015-01-01

    Molecular dynamics simulations are performed to compute thermomechanical properties of cured epoxy resins reinforced with pristine and covalently functionalized carbon nanotubes. A DGEBA-DDS epoxy network was built using the ‘dendrimer’ growth approach where 75% of available epoxy sites were cross-linked. The epoxy model is verified through comparisons to experiments, and simulations are performed on nanotube reinforced cross-linked epoxy matrix using the CVFF force field in LAMMPS. Full stiffness matrices and linear coefficient of thermal expansion vectors are obtained for the nanocomposite. Large increases in stiffness and large decreases in thermal expansion were seen along the direction of the nanotube for both nanocomposite systems when compared to neat epoxy. The direction transverse to nanotube saw a 40% increase in stiffness due to covalent functionalization over neat epoxy at 1 K whereas the pristine nanotube system only saw a 7% increase due to van der Waals effects. The functionalized SWNT/epoxy nanocomposite showed an additional 42% decrease in thermal expansion along the nanotube direction when compared to the pristine SWNT/epoxy nanocomposite. The stiffness matrices are rotated over every possible orientation to simulate the effects of an isotropic system of randomly oriented nanotubes in the epoxy. The randomly oriented covalently functionalized SWNT/Epoxy nanocomposites showed substantial improvements over the plain epoxy in terms of higher stiffness (200% increase) and lower thermal expansion (32% reduction). Through MD simulations, we develop means to build simulation cells, perform annealing to reach correct densities, compute thermomechanical properties and compare with experiments. (paper)

  20. Spark Plasma Sintering constrained process parameters of sintered silver paste for connection in power electronic modules: Microstructure, mechanical and thermal properties

    Energy Technology Data Exchange (ETDEWEB)

    Alayli, N. [Université Paris 13, Sorbonne Paris Cité, Laboratoire des Sciences des Procédés et des Matériaux, Centre National de la Recherche Scientifique, Unité Propre de Recherche 3407, 99 avenue Jean Baptiste Clément, F-93430 Villetaneuse (France); Université de Versailles-Saint-Quentin-en-Yvelines, Sorbonne Universités, Université Pierre et Marie Curie, Université Paris 06, Centre National de la Recherche Scientifique/INSU, Laboratoire Atmosphères Milieux Observations Spatiales-IPSL, Quartier des Garennes, 11 Boulevard d' Alembert, F-78280 Guyancourt (France); Schoenstein, F., E-mail: frederic.schoenstein@univ-paris13.fr [Université Paris 13, Sorbonne Paris Cité, Laboratoire des Sciences des Procédés et des Matériaux, Centre National de la Recherche Scientifique, Unité Propre de Recherche 3407, 99 avenue Jean Baptiste Clément, F-93430 Villetaneuse (France); Girard, A. [Office National d' Étude et de Recherches Aérospatiales, Laboratoire d' Étude des Microstructures, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 104, 29 avenue de la Division Leclerc, F-92322 Châtillon (France); and others

    2014-11-14

    Processing parameters of Spark Plasma Sintering (SPS) technique were constrained to process nano sized silver particles bound in a paste for interconnection in power electronic devices. A novel strategy combining debinding step and consolidation processes (SPS) in order to elaborate nano-structured silver bulk material is investigated. Optimum parameters were sought for industrial power electronics packaging from the microstructural and morphological properties of the sintered material. The latter was studied by Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) to determine the density and the grain size of crystallites. Two types of samples, termed S1 (bulk) and S2 (multilayer) were elaborated and characterized. They are homogeneous with a low degree of porosity and a good adhesion to the substrate and the process parameters are compatible with industrial constraints. As the experimental results show, the mean crystallite size is between 60 nm and 790 nm with a density between 50% and 92% resulting in mechanical and thermal properties that are better than that of lead free solder. The best SPS sintering parameters, the applied pressure, the temperature and the processing time were determined as being 3 MPa, 300 °C and 1 min respectively when the desizing time of the preprocessing step was kept below 5 min at 150 °C. Using these processing parameters, acceptable for automotive packaging industry, a semi-conductor power chip was successfully connected to a metalized substrate by sintered silver with thermal and electrical properties better than those of current solders and with thermomechanical properties allowing absorption of thermoplastic stresses. - Highlights: • The sintered silver joints have nanometric structure. • The grain growth was controlled by the SPS sintering parameters. • New connection material improve thermal and electrical properties of current solders. • Interconnection's plastic strain can absorb thermo-mechanical

  1. Mechanical, thermal and morphological characterization of polycarbonate/oxidized carbon nanofiber composites produced with a lean 2-step manufacturing process.

    Science.gov (United States)

    Lively, Brooks; Kumar, Sandeep; Tian, Liu; Li, Bin; Zhong, Wei-Hong

    2011-05-01

    In this study we report the advantages of a 2-step method that incorporates an additional process pre-conditioning step for rapid and precise blending of the constituents prior to the commonly used melt compounding method for preparing polycarbonate/oxidized carbon nanofiber composites. This additional step (equivalent to a manufacturing cell) involves the formation of a highly concentrated solid nano-nectar of polycarbonate/carbon nanofiber composite using a solution mixing process followed by melt mixing with pure polycarbonate. This combined method yields excellent dispersion and improved mechanical and thermal properties as compared to the 1-step melt mixing method. The test results indicated that inclusion of carbon nanofibers into composites via the 2-step method resulted in dramatically reduced ( 48% lower) coefficient of thermal expansion compared to that of pure polycarbonate and 30% lower than that from the 1-step processing, at the same loading of 1.0 wt%. Improvements were also found in dynamic mechanical analysis and flexural mechanical properties. The 2-step approach is more precise and leads to better dispersion, higher quality, consistency, and improved performance in critical application areas. It is also consistent with Lean Manufacturing principles in which manufacturing cells are linked together using less of the key resources and creates a smoother production flow. Therefore, this 2-step process can be more attractive for industry.

  2. Thermomechanical evaluation of BWR fuel elements for procedures of preconditioned with FEMAXI-V

    International Nuclear Information System (INIS)

    Hernandez L, H.; Lucatero, M.A.; Ortiz V, J.

    2006-01-01

    The limitations in the burnt of the nuclear fuel usually are fixed by the one limit in the efforts to that undergo them the components of a nuclear fuel assembly. The limits defined its provide the direction to the fuel designer to reduce to the minimum the fuel failure during the operation, and they also prevent against some thermomechanical phenomena that could happen during the evolution of transitory events. Particularly, a limit value of LHGR is fixed to consider those physical phenomena that could lead to the interaction of the pellet-shirt (Pellet Cladding Interaction, PCI). This limit value it is related directly with an PCI limit that can be fixed based on experimental tests of power ramps. This way, to avoid to violate the PCI limit, the conditioning procedures of the fuel are still required for fuel elements with and without barrier. Those simulation procedures of the power ramp are carried out for the reactor operator during the starting maneuvers or of power increase like preventive measure of possible consequences in the thermomechanical behavior of the fuel. In this work, the thermomechanical behavior of two different types of fuel rods of the boiling water reactor is analyzed during the pursuit of the procedures of fuel preconditioning. Five diverse preconditioning calculations were carried out, each one with three diverse linear ramps of power increments. The starting point of the ramps was taken of the data of the cycle 8 of the unit 1 of the Laguna Verde Nucleo electric Central. The superior limit superior of the ramps it was the threshold of the lineal power in which a fuel failure could be presented by PCI, in function of the fuel burnt. The analysis was carried out with the FEMAXI-V code. (Author)

  3. Effect of quinoa and potato flours on the thermomechanical and breadmaking properties ofwheat flour

    Directory of Open Access Journals (Sweden)

    E. Rodriguez-Sandoval

    2012-09-01

    Full Text Available The thermomechanical properties of dough and the physical characteristics of bread from quinoa-wheat and potato-wheat composite flours at 10 and 20% substitution level were evaluated. The functional properties of flours were measured by the water absorption index (WAI, water solubility index (WSI and swelling power (SP. The thermomechanical properties of wheat and composite flours were assessed using a Mixolab and the baking quality characteristics of breads were weight, height, width, and specific volume. The results showed that the higher values of WAI (4.48, WSI (7.45%, and SP (4.84 were for potato flour. The quinoa-wheat composite flour presented lower setback and cooking stability data, which are a good indicator of shelf life of bread. On the other hand, the potato-wheat composite flour showed lower stability, minimum torque and peak torque, and higher water absorption. Weight, height, width, and specific volume of wheat bread were most similar to samples of potato-wheat composite flour at 10% substitution level.

  4. Thermomechanical studies in granite at Stripa, Sweden

    International Nuclear Information System (INIS)

    Cook, N.G.W.; Myer, L.R.

    1981-01-01

    Media other than rock salt are being considered for the deep, geologic disposal of nuclear wastes. The disposal of high-level nuclear waste in a deep, underground repository will subject the rock to a thermal pulse that will induce displacements, strains, and stresses in the rock. Thermomechanical experiments, with electrical heaters simulating the thermal output of waste canisters, were carried out in granite at a depth of 340 m below surface adjacent to a defunct iron ore mine at Stripa, Sweden. Changes in temperature, displacement, and stress in the rock around these heaters were measured, and the measurements were compared with predictions calculated from the theory of linear thermoelasticity. Measured temperature changes agreed well with predictions, but measured displacements and stresses were consistently less than those predicted with constant values for the coefficient of thermal expansion and elastic properties of the rock. A laboratory test program to measure these coefficients over ranges of stress and temperature representing those in the field experiment has been initiated. Test specimens were taken from cores recovered from the instrumentation holes in the Stripa experiments. Preliminary results from laboratory tests on specimens free of joints indicate that the values of Young's modulus and Poisson's ratio increase from about 60 to 80 MPa and from 0.15 to 0.22, respectively, as the confining stress is increased from 2 to 55 MPa; these values decrease with increasing temperature, more so at 2 MPa than at 55 MPa. The linear coefficient of thermal expansion at a confining stress of 30 MPa increases from about 10 x 10 - 6 / 0 C at 40 0 C to about 14 x 10 - 6 / 0 C. The magnitudes of these changes are not sufficient to resolve the disparity between measured and predicted results. Perhaps the properties of test specimens containing joints will show greater variations in the values of the thermomechanical coefficients with temperature and pressure

  5. A Simple FEM Formulation Applied to Nonlinear Problems of Impact with Thermomechanical Coupling

    Directory of Open Access Journals (Sweden)

    João Paulo de Barros Cavalcante

    Full Text Available Abstract The thermal effects of problems involving deformable structures are essential to describe the behavior of materials in feasible terms. Verifying the transformation of mechanical energy into heat it is possible to predict the modifications of mechanical properties of materials due to its temperature changes. The current paper presents the numerical development of a finite element method suitable for nonlinear structures coupled with thermomechanical behavior; including impact problems. A simple and effective alternative formulation is presented, called FEM positional, to deal with the dynamic nonlinear systems. The developed numerical is based on the minimum potential energy written in terms of nodal positions instead of displacements. The effects of geometrical, material and thermal nonlinearities are considered. The thermodynamically consistent formulation is based on the laws of thermodynamics and the Helmholtz free-energy, used to describe the thermoelastic and the thermoplastic behaviors. The coupled thermomechanical model can result in secondary effects that cause redistributions of internal efforts, depending on the history of deformation and material properties. The numerical results of the proposed formulation are compared with examples found in the literature.

  6. Thermomechanical CSM analysis of a superheater tube in transient state

    Science.gov (United States)

    Taler, Dawid; Madejski, Paweł

    2011-12-01

    The paper presents a thermomechanical computational solid mechanics analysis (CSM) of a pipe "double omega", used in the steam superheaters in circulating fluidized bed (CFB) boilers. The complex cross-section shape of the "double omega" tubes requires more precise analysis in order to prevent from failure as a result of the excessive temperature and thermal stresses. The results have been obtained using the finite volume method for transient state of superheater. The calculation was carried out for the section of pipe made of low-alloy steel.

  7. Plasmonically enhanced thermomechanical detection of infrared radiation.

    Science.gov (United States)

    Yi, Fei; Zhu, Hai; Reed, Jason C; Cubukcu, Ertugrul

    2013-04-10

    Nanoplasmonics has been an attractive area of research due to its ability to localize and manipulate freely propagating radiation on the nanometer scale for strong light-matter interactions. Meanwhile, nanomechanics has set records in the sensing of mass, force, and displacement. In this work, we report efficient coupling between infrared radiation and nanomechanical resonators through nanoantenna enhanced thermoplasmonic effects. Using efficient conversion of electromagnetic energy to mechanical energy in this plasmo-thermomechanical platform with a nanoslot plasmonic absorber integrated directly on a nanobeam mechanical resonator, we demonstrate room-temperature detection of nanowatt level power fluctuations in infrared radiation. We expect our approach, which combines nanoplasmonics with nanomechanical resonators, to lead to optically controlled nanomechanical systems enabling unprecedented functionality in biomolecular and toxic gas sensing and on-chip mass spectroscopy.

  8. Impacting student anxiety for the USMLE Step 1 through process-oriented preparation

    Directory of Open Access Journals (Sweden)

    Roy E. Strowd

    2010-02-01

    Full Text Available Background: Standardized examinations are the key components of medical education. The USMLE Step 1 is the first of these important milestones. Success on this examination requires both content competency and efficient strategies for study and review. Students employ a wide variety of techniques in studying for this examination, with heavy reliance on personal study habits and advice from other students. Nevertheless, few medical curricula formally address these strategies. Methods: In response to student-generated critique at our institution, a five-part seminar series on process-oriented preparation was developed and implemented to address such concerns. The series focused on early guidance and preparation strategies for Step 1 and the many other important challenges in medical school. Emphasis was placed on facilitating conversation and mentorship opportunities between students. Results & Conclusions: A profoundly positive experience was reported by our medical students that included a decreased anxiety level for the Step 1 examination.

  9. Microwave assisted step-by-step process for the production of fucoidan, alginate sodium, sugars and biochar from Ascophyllum nodosum through a biorefinery concept.

    Science.gov (United States)

    Yuan, Yuan; Macquarrie, Duncan J

    2015-12-01

    The biorefinery is an important concept for the development of alternative routes to a range of interesting and important materials from renewable resources. It ensures that the resources are used fully and that all parts of them are valorized. This paper develops this concept, using brown macroalgae Ascophyllum nodosum as an example, by assistance of microwave technology. A step-by-step process was designed to obtain fucoidan, alginates, sugars and biochar (alga residue) consecutively. The yields of fucoidan, alginates, sugars and biochar were 14.09%, 18.24%, 10.87% and 21.44%, respectively. To make an evaluation of the biorefinery process, seaweed sample was also treated for fucoidan extraction only, alginate extraction only and hydrothermal treatment for sugars and biochar only. The chemical composition and properties of each product were also analyzed. The results indicated that A. nodosum could be potentially used as feedstock for a biorefinery process to produce valuable chemicals and fuels. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Thermomechanical Stress in Cryopreservation Via Vitrification With Nanoparticle Heating as a Stress-Moderating Effect.

    Science.gov (United States)

    Eisenberg, David P; Bischof, John C; Rabin, Yoed

    2016-01-01

    This study focuses on thermomechanical effects in cryopreservation associated with a novel approach of volumetric heating by means on nanoparticles in an alternating electromagnetic field. This approach is studied for the application of cryopreservation by vitrification, where the crystalline phase is completely avoided-the cornerstone of cryoinjury. Vitrification can be achieved by quickly cooling the material to cryogenic storage, where ice cannot form. Vitrification can be maintained at the end of the cryogenic protocol by quickly rewarming the material back to room temperature. The magnitude of the rewarming rates necessary to maintain vitrification is much higher than the magnitude of the cooling rates that are required to achieve it in the first place. The most common approach to achieve the required cooling and rewarming rates is by exposing the specimen's surface to a temperature-controlled environment. Due to the underlying principles of heat transfer, there is a size limit in the case of surface heating beyond which crystallization cannot be prevented at the center of the specimen. Furthermore, due to the underlying principles of solid mechanics, there is a size limit beyond which thermal expansion in the specimen can lead to structural damage and fractures. Volumetric heating during the rewarming phase of the cryogenic protocol can alleviate these size limitations. This study suggests that volumetric heating can reduce thermomechanical stress, when combined with an appropriate design of the thermal protocol. Without such design, this study suggests that the level of stress may still lead to structural damage even when volumetric heating is applied. This study proposes strategies to harness nanoparticles heating in order to reduce thermomechanical stress in cryopreservation by vitrification.

  11. Comparative analysis of single-step and two-step biodiesel production using supercritical methanol on laboratory-scale

    International Nuclear Information System (INIS)

    Micic, Radoslav D.; Tomić, Milan D.; Kiss, Ferenc E.; Martinovic, Ferenc L.; Simikić, Mirko Ð.; Molnar, Tibor T.

    2016-01-01

    Highlights: • Single-step supercritical transesterification compared to the two-step process. • Two-step process: oil hydrolysis and subsequent supercritical methyl esterification. • Experiments were conducted in a laboratory-scale batch reactor. • Higher biodiesel yields in two-step process at milder reaction conditions. • Two-step process has potential to be cost-competitive with the single-step process. - Abstract: Single-step supercritical transesterification and two-step biodiesel production process consisting of oil hydrolysis and subsequent supercritical methyl esterification were studied and compared. For this purpose, comparative experiments were conducted in a laboratory-scale batch reactor and optimal reaction conditions (temperature, pressure, molar ratio and time) were determined. Results indicate that in comparison to a single-step transesterification, methyl esterification (second step of the two-step process) produces higher biodiesel yields (95 wt% vs. 91 wt%) at lower temperatures (270 °C vs. 350 °C), pressures (8 MPa vs. 12 MPa) and methanol to oil molar ratios (1:20 vs. 1:42). This can be explained by the fact that the reaction system consisting of free fatty acid (FFA) and methanol achieves supercritical condition at milder reaction conditions. Furthermore, the dissolved FFA increases the acidity of supercritical methanol and acts as an acid catalyst that increases the reaction rate. There is a direct correlation between FFA content of the product obtained in hydrolysis and biodiesel yields in methyl esterification. Therefore, the reaction parameters of hydrolysis were optimized to yield the highest FFA content at 12 MPa, 250 °C and 1:20 oil to water molar ratio. Results of direct material and energy costs comparison suggest that the process based on the two-step reaction has the potential to be cost-competitive with the process based on single-step supercritical transesterification. Higher biodiesel yields, similar or lower energy

  12. Inorganic fullerene-like IF-WS_2/PVB nanocomposites of improved thermo-mechanical and tribological properties

    International Nuclear Information System (INIS)

    Simić, Danica; Stojanović, Dušica B.; Kojović, Aleksandar; Dimić, Mirjana; Totovski, Ljubica; Uskoković, Petar S.; Aleksić, Radoslav

    2016-01-01

    The subject of this research is to explore the possibility of preparation of nanocomposite material of improved thermo-mechanical and tribological properties, using inorganic fullerene-like tungsten disulfide nanostructures (IF-WS_2) as reinforcement in poly(vinyl butyral) (PVB). This paper also reports investigation of the effects of using different solvents in preparation of PVB/IF-WS_2 nanocomposite on the thermo-mechanical behavior of the resulting material. PVB was dissolved in ethanol, isopropanol, n-butanol and ethyl acetate. IF-WS_2 nanoparticles were added to these PVB solutions and dispersed by different deagglomeration techniques. Samples were dried and thin films were obtained. Their microstructure and the quality of IF-WS_2 dispersion and deagglomeration in PVB matrix was analyzed by scanning electron microscope (SEM). The reinforcing effect of IF-WS_2 is examined by determining hardness, reduced modulus of elasticity and coefficient of friction, by nanoindentation and nanoscratch test, in terms of the different solvents applied in preparation of the samples, mode of stirring and different contents of IF-WS_2. The glass transition temperature (T_g) was determined for the prepared samples using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA). Storage modulus and mechanical loss factor were observed in a defined temperature range using DMA. - Highlights: • Poly(vinyl butyral)/tungsten disulfide nanocomposites were examined. • Different solvents and deagglomeration methods affect the properties of composites. • Nanoindentation and scratch test, PSD, SEM, DSC and DMTA were analyzed. • Thermo-mechanical and antifriction properties of composite material are improved.

  13. Parametric optimization of the MVC desalination plant with thermomechanical compressor

    Science.gov (United States)

    Blagin, E. V.; Biryuk, V. V.; Anisimov, M. Y.; Shimanov, A. A.; Gorshkalev, A. A.

    2018-03-01

    This article deals with parametric optimization of the Mechanical Vapour Compression (MVC) desalination plant with thermomechanical compressor. In this plants thermocompressor is used instead of commonly used centrifugal compressor. Influence of two main parameters was studied. These parameters are: inlet pressure and number of stages. Analysis shows that it is possible to achieve better plant performance in comparison with traditional MVC plant. But is required reducing the number of stages and utilization of low or high initial pressure with power consumption maximum at approximately 20-30 kPa.

  14. A two-step annealing process for enhancing the ferroelectric properties of poly(vinylidene fluoride) (PVDF) devices

    KAUST Repository

    Park, Jihoon

    2015-01-01

    We report a simple two-step annealing scheme for the fabrication of stable non-volatile memory devices employing poly(vinylidene fluoride) (PVDF) polymer thin-films. The proposed two-step annealing scheme comprises the crystallization of the ferroelectric gamma-phase during the first step and enhancement of the PVDF film dense morphology during the second step. Moreover, when we extended the processing time of the second step, we obtained good hysteresis curves down to 1 Hz, the first such report for ferroelectric PVDF films. The PVDF films also exhibit a coercive field of 113 MV m-1 and a ferroelectric polarization of 5.4 μC cm-2. © The Royal Society of Chemistry 2015.

  15. Reliable high-power diode lasers: thermo-mechanical fatigue aspects

    Science.gov (United States)

    Klumel, Genady; Gridish, Yaakov; Szafranek, Igor; Karni, Yoram

    2006-02-01

    High power water-cooled diode lasers are finding increasing demand in biomedical, cosmetic and industrial applications, where repetitive cw (continuous wave) and pulsed cw operation modes are required. When operating in such modes, the lasers experience numerous complete thermal cycles between "cold" heat sink temperature and the "hot" temperature typical of thermally equilibrated cw operation. It is clearly demonstrated that the main failure mechanism directly linked to repetitive cw operation is thermo-mechanical fatigue of the solder joints adjacent to the laser bars, especially when "soft" solders are used. Analyses of the bonding interfaces were carried out using scanning electron microscopy. It was observed that intermetallic compounds, formed already during the bonding process, lead to the solders fatigue both on the p- and n-side of the laser bar. Fatigue failure of solder joints in repetitive cw operation reduces useful lifetime of the stacks to hundreds hours, in comparison with more than 10,000 hours lifetime typically demonstrated in commonly adopted non-stop cw reliability testing programs. It is shown, that proper selection of package materials and solders, careful design of fatigue sensitive parts and burn-in screening in the hard pulse operation mode allow considerable increase of lifetime and reliability, without compromising the device efficiency, optical power density and compactness.

  16. Thermo-Mechanical Modeling of Laser-Mig Hybrid Welding (lmhw)

    Science.gov (United States)

    Kounde, Ludovic; Engel, Thierry; Bergheau, Jean-Michel; Boisselier, Didier

    2011-01-01

    Hybrid welding is a combination of two different technologies such as laser (Nd: YAG, CO2…) and electric arc welding (MIG, MAG / TIG …) developed to assemble thick metal sheets (over 3 mm) in order to reduce the required laser power. As a matter of fact, hybrid welding is a lso used in the welding of thin materials to benefit from process, deep penetration and gap limit. But the thermo-mechanical behaviour of thin parts assembled by LMHW technology for railway cars production is far from being controlled the modeling and simulation contribute to the assessment of the causes and effects of the thermo mechanical behaviour in the assembled parts. In order to reproduce the morphology of melted and heat-affected zones, two analytic functions were combined to model the heat source of LMHW. On one hand, we applied a so-called "diaboloïd" (DB) which is a modified hyperboloid, based on experimental parameters and the analysis of the macrographs of the welds. On the other hand, we used a so-called "double ellipsoïd" (DE) which takes the MIG only contribution including the bead into account. The comparison between experimental result and numerical result shows a good agreement.

  17. Progress in thermomechanical control of steel plates and their commercialization

    Science.gov (United States)

    Nishioka, Kiyoshi; Ichikawa, Kazutoshi

    2012-01-01

    The water-cooled thermomechanical control process (TMCP) is a technology for improving the strength and toughness of water-cooled steel plates, while allowing control of the microstructure, phase transformation and rolling. This review describes metallurgical aspects of the microalloying of steel, such as niobium addition, and discusses advantages of TMCP, for example, in terms of weldability, which is reduced upon alloying. Other covered topics include the development of equipment, distortions in steel plates, peripheral technologies such as steel making and casting, and theoretical modeling, as well as the history of property control in steel plate production and some early TMCP technologies. We provide some of the latest examples of applications of TMCP steel in various industries such as shipbuilding, offshore structures, building construction, bridges, pipelines, penstocks and cryogenic tanks. This review also introduces high heat-affected-zone toughness technologies, wherein the microstructure of steel is improved by the addition of fine particles of magnesium-containing sulfides and magnesium- or calcium-containing oxides. We demonstrate that thanks to ongoing developments TMCP has the potential to meet the ever-increasing demands of steel plates. PMID:27877477

  18. Thermomechanical Fatigue of Ductile Cast Iron and Its Life Prediction

    Science.gov (United States)

    Wu, Xijia; Quan, Guangchun; MacNeil, Ryan; Zhang, Zhong; Liu, Xiaoyang; Sloss, Clayton

    2015-06-01

    Thermomechanical fatigue (TMF) behaviors of ductile cast iron (DCI) were investigated under out-of-phase (OP), in-phase (IP), and constrained strain-control conditions with temperature hold in various temperature ranges: 573 K to 1073 K, 723 K to 1073 K, and 433 K to 873 K (300 °C to 800 °C, 450 °C to 800 °C, and 160 °C to 600 °C). The integrated creep-fatigue theory (ICFT) model was incorporated into the finite element method to simulate the hysteresis behavior and predict the TMF life of DCI under those test conditions. With the consideration of four deformation/damage mechanisms: (i) plasticity-induced fatigue, (ii) intergranular embrittlement, (iii) creep, and (iv) oxidation, as revealed from the previous study on low cycle fatigue of the material, the model delineates the contributions of these physical mechanisms in the asymmetrical hysteresis behavior and the damage accumulation process leading to final TMF failure. This study shows that the ICFT model can simulate the stress-strain response and life of DCI under complex TMF loading profiles (OP and IP, and constrained with temperature hold).

  19. Progress in thermomechanical control of steel plates and their commercialization

    Directory of Open Access Journals (Sweden)

    Kiyoshi Nishioka and Kazutoshi Ichikawa

    2012-01-01

    Full Text Available The water-cooled thermomechanical control process (TMCP is a technology for improving the strength and toughness of water-cooled steel plates, while allowing control of the microstructure, phase transformation and rolling. This review describes metallurgical aspects of the microalloying of steel, such as niobium addition, and discusses advantages of TMCP, for example, in terms of weldability, which is reduced upon alloying. Other covered topics include the development of equipment, distortions in steel plates, peripheral technologies such as steel making and casting, and theoretical modeling, as well as the history of property control in steel plate production and some early TMCP technologies. We provide some of the latest examples of applications of TMCP steel in various industries such as shipbuilding, offshore structures, building construction, bridges, pipelines, penstocks and cryogenic tanks. This review also introduces high heat-affected-zone toughness technologies, wherein the microstructure of steel is improved by the addition of fine particles of magnesium-containing sulfides and magnesium- or calcium-containing oxides. We demonstrate that thanks to ongoing developments TMCP has the potential to meet the ever-increasing demands of steel plates.

  20. Comparison of the thermomechanical characteristics of porcher carbon fabric-based composites for orthopaedic applications

    Science.gov (United States)

    Molchanov, E. S.; Yudin, V. E.; Kydralieva, K. A.; Elokhovskii, V. Yu.

    2012-07-01

    Prepregs of fiber-reinforced plastics based on a PORCHER-43200 carbon twill-weave fabric and two types of binders — thermoreactive and thermoplastic — were fabricated using electrostatic spraying, followed by rolling the prepregs in temperature-controlled calenders. A solid epoxy olygomer with dicyandiamine as a hardener and Fortron® polyphenylene sulfide were used as the thermoreactive and thermoplastic binders. The thermomechanical properties of carbon-fiber-reinforced plastics processed from these prepregs, as well as commercial Sigranex® PREPREGCE8201-200-45 S prepregs as model ones, and composites manufactured from them were investigated for comparison. The latter ones are being used for the design of orthopaedic products. It is shown that the composites based on polyphenylene sulfide are characterized by higher values of flexural strength, flexural and shear moduli, and interlaminar fracture toughness ( G IC), the latter being the most important parameter.

  1. Thermo-mechanical properties of mixed ion-electron conducting membrane materials

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bingxin

    2011-07-01

    The thesis presents thermo-mechanical properties of La{sub 0.58}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCF) and Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF) perovskite materials, which are considered as oxygen transport membranes (OTM) for gas separation units. Ring-on-ring bending test with disk-shaped samples and depth-sensitive micro-indentation have been used as macroscopic and microscopic tests, respectively. In addition, the thermo-mechanical properties of a third OTM candidate material La{sub 2}NiO{sub 4+{delta}} (LNO) were investigated. The results of the thermo-mechanical measurements with the BSCF revealed an anomaly between 200 C and 400 C. In particular, the temperature dependence of Young's modulus shows a minimum at {proportional_to} 200 C. Fracture stress and toughness exhibit a qualitatively similar behavior with a minimum between 200 C and 400 C, before recovering between 500 C and 800 C. X-ray diffraction analyses verified that BSCF remains cubic in the relevant temperature range. Hence the anomalies were assumed to be related to the transition of Co{sup 3+} spin states reported for other Co-containing perovskites. This assumption could be experimentally confirmed by magnetic susceptibility measurements. The fracture surfaces of the specimens are not affected by the mechanical anomalies at intermediate temperatures, since only a transgranular fracture mode has been observed. Complementary to the mechanical characterization of BSCF, also the temperature dependency of fracture stress and elastic behavior of LSCF have been determined. Phase compositions of LSCF have been studied by in-situ high temperature XRD. Changes in phase composition with temperature are observed. At ambient temperature the LSCF perovskite material comprises two phases: rhombohedral and cubic symmetry. The ratio of the two phases depends on both cooling rate and atmosphere. The transition of rhombohedral to cubic occurs between 700 C and

  2. Advanced Environmental Barrier Coating and SA Tyrannohex SiC Composites Integration for Improved Thermomechanical and Environmental Durability

    Science.gov (United States)

    Zhu, Dongming; Halbig, Michael; Singh, Mrityunjay

    2018-01-01

    The development of 2700 degF capable environmental barrier coating (EBC) systems, particularly, the Rare Earth "Hafnium" Silicon bond coat systems, have significantly improved the temperature capability and environmental stability of SiC/SiC Ceramic Matrix Composite Systems. We have specifically developed the advanced 2700 degF EBC systems, integrating the EBC to the high temperature SA Tyrannohex SiC fiber composites, for comprehensive performance and durability evaluations for potential turbine engine airfoil component applications. The fundamental mechanical properties, environmental stability and thermal gradient cyclic durability performance of the EBC - SA Tyrannohex composites were investigated. The paper will particularly emphasize the high pressure combustion rig recession, cyclic thermal stress resistance and thermomechanical low cycle fatigue testing of uncoated and environmental barrier coated Tyrannohex SiC SA composites in these simulated turbine engine combustion water vapor, thermal gradients, and mechanical loading conditions. We have also investigated high heat flux and flexural fatigue degradation mechanisms, determined the upper limits of operating temperature conditions for the coated SA composite material systems in thermomechanical fatigue conditions. Recent progress has also been made by using the self-healing rare earth-silicon based EBCs, thus enhancing the SA composite hexagonal fiber columns bonding for improved thermomechanical and environmental durability in turbine engine operation environments. More advanced EBC- composite systems based on the new EBC-Fiber Interphases will also be discussed.

  3. Thermo-mechanical analysis of a user filter assembly for undulator/wiggler operations at the Advanced Photon Source

    International Nuclear Information System (INIS)

    Nian, H.L.T.; Kuzay, T.M.; Collins, J.; Shu, D.; Benson, C.; Dejus, R.

    1996-01-01

    This paper reports a thermo-mechanical study of a beamline filter (user filter) for undulator/wiggler operations. It is deployed in conjunction with the current commissioning window assembly on the APS insertion device (ID) front ends. The beamline filter at the Advanced Photon Source (APS) will eventually be used in windowless operations also. Hence survival and reasonable life expectancy of the filters under intense insertion device (ID) heat flu are crucial to the beamline operations. To accommodate various user requirements, the filter is configured to be a multi-choice type and smart to allow only those filter combinations that will be safe to operate with a given ring current and beamline insertion device gap. However, this paper addresses only the thermo-mechanical analysis of individual filter integrity and safety in all combinations possible. The current filter design is configured to have four filter frames in a cascade with each frame holding five filters. This allows a potential 625 total filter combinations. Thermal analysis for all of these combinations becomes a mammoth task considering the desired choices for filter materials (pyrolitic graphite and metallic filters), filter thicknesses, undulator gaps, and the beam currents. The paper addresses how this difficult task has been reduced to a reasonable effort and computational level. Results from thermo-mechanical analyses of the filter combinations are presented both in tabular and graphical format

  4. Thermo-mechanical efficiency of the bimetallic strip heat engine at the macro-scale and micro-scale

    International Nuclear Information System (INIS)

    Arnaud, A; Boughaleb, J; Monfray, S; Boeuf, F; Skotnicki, T; Cugat, O

    2015-01-01

    Bimetallic strip heat engines are energy harvesters that exploit the thermo-mechanical properties of bistable bimetallic membranes to convert heat into mechanical energy. They thus represent a solution to transform low-grade heat into electrical energy if the bimetallic membrane is coupled with an electro-mechanical transducer. The simplicity of these devices allows us to consider their miniaturization using MEMS fabrication techniques. In order to design and optimize these devices at the macro-scale and micro-scale, this article proposes an explanation of the origin of the thermal snap-through by giving the expressions of the constitutive equations of composite beams. This allows us to evaluate the capability of bimetallic strips to convert heat into mechanical energy whatever their size is, and to give the theoretical thermo-mechanical efficiencies which can be obtained with these harvesters. (paper)

  5. Extended Kalman filter (EKF) application in vitamin C two-step fermentation process.

    Science.gov (United States)

    Wei, D; Yuan, W; Yuan, Z; Yin, G; Chen, M

    1993-01-01

    Based on kinetic model study of vitamin C two-step fermentation, the extended Kalman filter (EKF) theory is conducted for studying the process which is disturbed by white noise to some extent caused by the model, the fermentation system and operation fluctuation. EKF shows that calculated results from estimated process parameters agree with the experimental results considerably better than model prediction without using estimated parameters. Parameter analysis gives a better understanding of the kinetics and provides a basis for state estimation and state prediction.

  6. A thermomechanical constitutive model for cemented granular materials with quantifiable internal variables. Part I-Theory

    Science.gov (United States)

    Tengattini, Alessandro; Das, Arghya; Nguyen, Giang D.; Viggiani, Gioacchino; Hall, Stephen A.; Einav, Itai

    2014-10-01

    This is the first of two papers introducing a novel thermomechanical continuum constitutive model for cemented granular materials. Here, we establish the theoretical foundations of the model, and highlight its novelties. At the limit of no cement, the model is fully consistent with the original Breakage Mechanics model. An essential ingredient of the model is the use of measurable and micro-mechanics based internal variables, describing the evolution of the dominant inelastic processes. This imposes a link between the macroscopic mechanical behavior and the statistically averaged evolution of the microstructure. As a consequence this model requires only a few physically identifiable parameters, including those of the original breakage model and new ones describing the cement: its volume fraction, its critical damage energy and bulk stiffness, and the cohesion.

  7. Effects of thermomechanical process on the microstructure and mechanical properties of a fully martensitic titanium-based biomedical alloy.

    Science.gov (United States)

    Elmay, W; Prima, F; Gloriant, T; Bolle, B; Zhong, Y; Patoor, E; Laheurte, P

    2013-02-01

    Thermomechanical treatments have been proved to be an efficient way to improve superelastic properties of metastable β type titanium alloys through several studies. In this paper, this treatment routes, already performed on superelastic alloys, are applied to the Ti-24Nb alloy (at%) consisting of a pure martensite α'' microstructure. By short-time annealing treatments performed on the heavily deformed material, an interesting combination of a large recoverable strain of about 2.5%, a low elastic modulus (35 GPa) and a high strength (900 MPa) was achieved. These properties are shown to be due to a complex microstructure consisting of the precipitation of nanoscale (α+ω) phases in ultra-fine β grains. This microstructure allows a superelastic behavior through stress-induced α'' martensitic transformation. In this study, the microstructures were characterized by X-ray diffraction and transmission electron microscopy and the evolution of the elastic modulus and the strain recovery as a function of the applied strain was investigated through loading-unloading tensile tests. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Single-step solution processing of small-molecule organic semiconductor field-effect transistors at high yield

    NARCIS (Netherlands)

    Yu, Liyang; Li, X.; Pavlica, E.; Loth, M.A.; Anthony, J.E.; Bratina, G.; Kjellander, B.K.C.; Gelinck, G.H.; Stutzmann, N.

    2011-01-01

    Here, we report a simple, alternative route towards high-mobility structures of the small-molecular semiconductor 5,11-bis(triethyl silylethynyl) anthradithiophene that requires one single processing step without the need for any post-deposition processing. The method relies on careful control of

  9. Residual stresses in multilayer ceramic capacitors: measurement and computation

    NARCIS (Netherlands)

    Toonder, den J.M.J.; Rademaker, C.W.; Hu, C.L.

    2003-01-01

    In this paper, we present a combined experimental and computational study of the thermomechanical reliability of multilayer ceramic capacitors (MLCC's). We focus on residual stresses introduced into the components during the cooling down step of the sintering process. The technique of

  10. Thermomechanical analyses of conceptual repository designs for the Paradox and Permian Basins

    International Nuclear Information System (INIS)

    Loken, M.C.; Callahan, G.D.; Svalstad, D.K.; Wagner, R.A.

    1987-11-01

    The potential repositories are designed to accommodate all waste forms emplaced at various thermal loadings; specifically, commercial high-level waste (30 W/m 2 ), spent fuel (15 W/m 2 ), defense high-level waste (20 W/m 2 ), and remote-handled and contact-handled transuranic nonheat-generating waste. The study evaluates the design parameters, primarily thermal loading, based on a comparison of calculable thermomechanical parameters with prescribed performance constraints. This evaluation was accomplished by numerical simulation using finite element techniques of the canister, disposal room, and repository regions of each potential site. Important thermal and thermomechanical results were compared with their prescribed constraint or limit value. All of the performance constraints were satisfied at the Davis Canyon site in the Paradox Basin for commercial high-level waste, spent fuel, and defense high-level waste at areal thermal loadings of 20 W/m 2 , 15 W/m 2 , and 20 W/m 2 , respectively. Similarly, for the Deaf Smith County site in the Permian Basin, commercial high-level waste, spent fuel, and defense high-level waste thermal loadings of 13.5 W/m 2 , 8.5 W/m 2 , and 6.0 W/m 2 , respectively, satisfied all of the performance constraints. 89 refs., 64 figs., 22 tabs

  11. Thermomechanical damage of nucleosome by the shock wave initiated by ion passing through liquid water

    International Nuclear Information System (INIS)

    Yakubovich, Alexander V.; Surdutovich, Eugene; Solov’yov, Andrey V.

    2012-01-01

    We report on the results of full-atom molecular dynamics simulations of the heat spike in the water medium caused by the propagation of the heavy ion in the vicinity of its Bragg peak. High rate of energy transfer from an ion to the molecules of surrounding water environment leads to the rapid increase of the temperature of the molecules in the vicinity of ions trajectory. As a result of an abrupt increase of the temperature we observe the formation of the nanoscale shock wave propagating through the medium. We investigate the thermomechanical damage caused by the shock wave to the nucleosome located in the vicinity of heavy ion trajectory. We observe the substantial deformation of the DNA secondary structure. We show that the produced shock wave can lead to the thermomechanical breakage of the DNA backbone covalent bonds and present estimates for the number of such strand brakes per one cell nucleus.

  12. Hydrogen with intrinsic CO{sub 2} sequestration: the ENI 'One Step Hydrogen' process

    Energy Technology Data Exchange (ETDEWEB)

    Rossini, S.; Cornaro, U.; Mizia, F.; Malandrino, A.; Piccoli, V. [Enitecnologie SpA, S. Donata Milanese (Italy); Sanfilippo, D.; Miracca, I. [Snamprogetti SpA, S. Donato Milanese (Italy)

    2003-07-01

    The new process, under development in our companies, is aimed to hydrogen production with intrinsic carbon dioxide sequestration. This is made possible combining in a cycle the water oxidative potential with a reverse action by a reducing agent like hydrocarbons, the preferred being natural gas. In the first step a suitable oxide takes up the oxygen from water splitting producing hydrogen. The solid act as an oxygen storage medium. Such 'lattice' oxygen is in turn released through one or more elemental steps. The process fits very well with a circulating fluid bed reactor which allows the movement of the solid from one reactive environment to the other. (orig.)

  13. Modelling of the thermomechanical behaviour of saturated clays: application to the radioactive wastes disposal

    International Nuclear Information System (INIS)

    Rahbaoui, A.

    1995-01-01

    During the waste disposal of containers, the clay barriers of backfill and the confining medium, which is essentially composed of clay, are submitted to heavy thermal stresses which induce volume change and can result in material failure. The clay, composed of solid skeleton, adsorbed water, and free water, is submitted to physico-chemical interactions which influence its thermomechanical behaviour, itself quits different from granular media such as sand. The principal factor responsible for this response is the effect of temperature on the clays water. Thus, the loss of special structure of adsorbed water and the increase in thickness of the diffused double-layer provoke microstructural rearrangement mechanisms of particles. Those mechanisms are strongly correlated with the mechanical state of material. When it is highly over-consolidated, an irreversible swelling occurs during thermal cycle, accompanied by a breaking up of the particles and a permanent expansion of meso-pores. The greater the OCR, the more important the thermal swelling. When the material is normally consolidated, the particles settle during heating under the external stress, which results in a denser rearrangement of the material. With a slight over-consolidated material, all the intermediate stages between the above mechanisms can be reached. However, cooling produces only a weak reversible compression characterising the thermal contraction of the components. Those microscopic phenomena have been used to elaborate a macroscopic thermomechanical model based on the Cam-Clay and the Hujeux Models. The model formulation includes a thermal softening, on one hand, by the reduction of the mechanical yield surface f c and the translation of the thermal yield surface f T (PTL), and, on the other hand, an irreversible thermal expansive volumetric strain. This approach of the problem was tested along various thermomechanical paths and especially on the laboratory tests, on the expansive and non expansive

  14. Biodiesel production from microalgae Spirulina maxima by two step process: Optimization of process variable

    Directory of Open Access Journals (Sweden)

    M.A. Rahman

    2017-04-01

    Full Text Available Biodiesel from green energy source is gaining tremendous attention for ecofriendly and economically aspect. In this investigation, a two-step process was developed for the production of biodiesel from microalgae Spirulina maxima and determined best operating conditions for the steps. In the first stage, acid esterification was conducted to lessen acid value (AV from 10.66 to 0.51 mgKOH/g of the feedstock and optimal conditions for maximum esterified oil yielding were found at molar ratio 12:1, temperature 60°C, 1% (wt% H2SO4, and mixing intensity 400 rpm for a reaction time of 90 min. The second stage alkali transesterification was carried out for maximum biodiesel yielding (86.1% and optimal conditions were found at molar ratio 9:1, temperature 65°C, mixing intensity 600 rpm, catalyst concentration 0.75% (wt% KOH for a reaction time of 20 min. Biodiesel were analyzed according to ASTM standards and results were within standards limit. Results will helpful to produce third generation algal biodiesel from microalgae Spirulina maxima in an efficient manner.

  15. One step processing for future diesel specifications

    International Nuclear Information System (INIS)

    Brierley, G.R.

    1997-01-01

    The trend in diesel fuel specifications is to limit the sulfur level to less than 0.05 wt- per cent. Many regions have also specified that diesel fuels must have lower aromatic levels, higher cetane numbers, and lower distillation end points. These changes will require significant refinery investment to meet the new diesel fuel specifications. The changes may also significantly affect the value of synthetic crude stocks. UOP has developed a new hydroprocessing catalyst which makes it possible to meet the new diesel specifications in one single processing step and at minimal cost. The catalyst saturates aromatics while opening ring structures at the same time. By selectively cracking heavy components into the diesel range with minimal cracking to gas or naphtha, heavier feedstocks can be upgraded to diesel, and refinery diesel yield can be augmented. Synthetic crude distillate is often high in aromatics and low in cetane number. This new UOP hydroprocessing system will allow synthetic crude producers and refiners to produce diesel fuels with higher cetane numbers, high-quality distillate blendstocks and distillate fuels. 26 figs

  16. Finite Element Analysis of the Deformation of Functionally Graded Plates under Thermomechanical Loads

    Directory of Open Access Journals (Sweden)

    A. E. Alshorbagy

    2013-01-01

    Full Text Available The first-order shear deformation plate model, accounting for the exact neutral plane position, is exploited to investigate the uncoupled thermomechanical behavior of functionally graded (FG plates. Functionally graded materials are mainly constructed to operate in high temperature environments. Also, FG plates are used in many applications (such as mechanical, electrical, and magnetic, where an amount of heat may be generated into the FG plate whenever other forms of energy (electrical, magnetic, etc. are converted into thermal energy. Several simulations are performed to study the behavior of FG plates, subjected to thermomechanical loadings, and focus the attention on the effect of the heat source intensity. Most of the previous studies have considered the midplane neutral one, while the actual position of neutral plane for functionally graded plates is shifted and should be firstly determined. A comparative study is performed to illustrate the effect of considering the neutral plane position. The volume fraction of the two constituent materials of the FG plate is varied smoothly and continuously, as a continuous power function of the material position, along the thickness of the plate.

  17. Microstructural Characterization of Thermomechanical and Heat-Affected Zones of an Inertia Friction Welded Astroloy

    Science.gov (United States)

    Oluwasegun, K. M.; Olawale, J. O.; Ige, O. O.; Shittu, M. D.; Adeleke, A. A.; Malomo, B. O.

    2014-08-01

    The behaviour of γ' phase to thermal and mechanical effects during rapid heating of Astroloy, a powder metallurgy nickel-based superalloy has been investigated. The thermo-mechanical-affected zone (TMAZ) and heat-affected zone (HAZ) microstructures of an inertia friction welded (IFW) Astroloy were simulated using a Gleeble thermo-mechanical simulation system. Detailed microstructural examination of the simulated TMAZ and HAZ and those present in actual IFW specimens showed that γ' particles persisted during rapid heating up to a temperature where the formation of liquid is thermodynamically favored and subsequently re-solidified eutectically. The result obtained showed that forging during the thermo-mechanical simulation significantly enhanced resistance to weld liquation cracking of the alloy. This is attributable to strain-induced rapid isothermal dissolution of the constitutional liquation products within 150 μm from the center of the forged sample. This was not observed in purely thermally simulated samples. The microstructure within the TMAZ of the as-welded alloy is similar to the microstructure in the forged Gleeble specimens.

  18. Thermomechanical behavior of Fe-Mn-Si-Cr-Ni shape memory alloys modified with samarium

    International Nuclear Information System (INIS)

    Shakoor, R.A.; Khalid, F. Ahmad

    2009-01-01

    The deformation and training behavior of Fe-14Mn-3Si-10Cr-5Ni (wt.%) shape memory alloys containing samarium addition has been studied in the iron-based shape memory alloys. It is noticed that thermomechanical treatment (training) has significant influence on proof stress, critical stress and shape memory behavior of the alloys. The improvement in shape memory behavior can be attributed to the decrease in the proof stress and critical stress which facilitates the formation of ε (hcp martensite). It is also observed that alloy 2 containing samarium undergoes less softening as compared to alloy 1 with training which inhibits the formation of α (bcc martensite) and thus enhances the shape memory behavior. The excessive thermomechanical treatment with increase in the training cycle has led to the formation of α (bcc martensite) along with ε (hcp martensite) in the alloy 1 which appeared to have decline in the shape memory effect. This has been demonstrated by the examination of microstructure and identification of α (bcc martensite) martensite in the alloy 1 as compared to alloy 2

  19. Fuel element thermo-mechanical analysis during transient events using the FMS and FETMA codes

    International Nuclear Information System (INIS)

    Hernandez Lopez Hector; Hernandez Martinez Jose Luis; Ortiz Villafuerte Javier

    2005-01-01

    In the Instituto Nacional de Investigaciones Nucleares of Mexico, the Fuel Management System (FMS) software package has been used for long time to simulate the operation of a BWR nuclear power plant in steady state, as well as in transient events. To evaluate the fuel element thermo-mechanical performance during transient events, an interface between the FMS codes and our own Fuel Element Thermo Mechanical Analysis (FETMA) code is currently being developed and implemented. In this work, the results of the thermo-mechanical behavior of fuel rods in the hot channel during the simulation of transient events of a BWR nuclear power plant are shown. The transient events considered for this work are a load rejection and a feedwater control failure, which among the most important events that can occur in a BWR. The results showed that conditions leading to fuel rod failure at no time appeared for both events. Also, it is shown that a transient due load rejection is more demanding on terms of safety that the failure of a controller of the feedwater. (authors)

  20. Development of F2 two-step fluorination process for non-aqueous reprocessing

    International Nuclear Information System (INIS)

    1976-02-01

    To establish the F 2 two-step fluorination for stable and high recoveries of plutonium, the fluorination process has been studied with the simulated fuel to a FBR containing UO 2 - PuO 2 and non-radioactive fission products in the 2''phi fluid-bed. The process principle was demonstrated and the effect of FPs on fluorination of U and Pu and the possibility of reducing the Pu loss could be clarified. The feasibility of separating PuF 6 from UF 6 onto UO 2 F 2 by adsorption, was also indicated. (auth.)

  1. Disciplinary Counseling: The First Step toward Due Process.

    Science.gov (United States)

    Cunningham, Patrick J.

    1980-01-01

    The oral reprimand is seen as the most important step in a corrective discipline procedure. Steps of disciplinary counseling include: always counsel in a private place; identify the problem; identify the desired behavior; define the consequences; get commitment from employee; identify session as oral reprimand; and monitor and follow up.(MLW)

  2. High heat flux tests of the WENDELSTEIN 7-X pre-series target elements - experimental evaluation of the thermo-mechanical behaviour

    International Nuclear Information System (INIS)

    Greuner, H.; Boeswirth, B.; Boscary, J.; Plankensteiner, A.; Schedler, B.

    2006-01-01

    The HHF testing of WENDELSTEIN 7-X pre-series target elements is an indispensable step in the qualification of the manufacturing process. The finally 890 divertor target elements are made of an actively water-cooled CuCrZr heat sink covered with flat tiles of CFC NB31 as plasma facing material. A set of 20 full scale pre-series elements was manufactured by PLANSEE to validate the materials and manufacturing technologies prior to the start of the series production. Due to the large mismatch in the coefficients of thermal expansion for CFC and CuCrZr - resulting in high residual stresses as well as high operation-induced stresses - the bonding zone between CFC and CuCrZr was detected to be the most critical issue for the operational behaviour of the target elements. To achieve a sufficiently high manufacturing quality together with a high lifetime during operation thermal testing of full scale mockups was performed in combination with extensive FEM analyses. In both cases heat loads were applied similar to the expected heat loads in W7-X. All pre-series elements were tested in the ion beam test facility GLADIS. The elements were tested with 100 cycles of 10 MW/m 2 and several elements with even higher cycle numbers and heat loads up to 24 MW/m 2 . The instrumentation of the targets (thermocouples, strain gages) and the infrared camera observation of the heat loaded surface allow an experimental evaluation of the thermo-mechanical behaviour of the tested elements. The main result is a good agreement between experimental data and numerically computed predictions. Hot spots were, however, observed at the edges of several tiles during the HHF tests indicating local bonding problems. Therefore, a programme of fully 3D nonlinear thermal-mechanical FEM calculations was started to evaluate the thermo-mechanical behavior of the target elements with special focus on the optimization of the stress situation in the bonding zone between the CFC and the CuCrZr heat sink. This

  3. Thermo-mechanical tests on W7-X current lead flanges

    International Nuclear Information System (INIS)

    Dhard, Chandra Prakash; Rummel, Thomas; Zacharias, Daniel; Bykov, Victor; Moennich, Thomas; Buscher, Klaus-Peter

    2013-01-01

    Highlights: • There are significant mechanical loads on the cryostat and radial flanges for W7-X current leads. • These are due to evacuation of W7-X cryostat, cool-down of cold mass, electro-magnetic forces and self weight of leads. • The actual mechanical loads were reduced to simplify the experimental set-up. • The tests were carried out on mock-up flanges test assembly at ambient temperature and at 77 K. • The thermo-mechanical tests on W7-X current lead flanges validate the design and joints of these flanges to the leads. -- Abstract: Fourteen pieces of high temperature superconducting current leads (CL) arranged in seven pairs, will be installed on the outer vessel of Wendelstein 7-X (W7-X) stellarator. In order to support the CL, it is provided with two glass fiber reinforce plastic (GFRP) flanges, namely, the lower cryostat flange (CF) remaining at room temperature and upper radial flange (RF) at about 5 K. Both the flanges i.e. CF and RF experience high mechanical loads with respect to the CL, due to the evacuation of W7-X cryostat, cool-down of cold mass including the CL, electro-magnetic forces due to current and plasma operations and self weight of CL. In order to check the integrity of these flanges for such mechanical loads, thermo-mechanical tests were carried out on these flanges at room temperatures and at liquid nitrogen (LN2) temperatures. The details of test set-up, results and modeling are described in the paper

  4. Computerized simulation of YAG pulse laser welding of titanium alloy (TA6V): experimental characterization and modelling of the thermomechanical aspects of this process; Simulation numerique du soudage du TA6V par laser YAG impulsionnel: caracterisation experimentale et modelisation des aspects thermomecanique associees a ce procede

    Energy Technology Data Exchange (ETDEWEB)

    Robert, Y

    2007-09-15

    This work is a part of study which goal is to realize a computer modelling of the thermomechanical phenomena occurring during the YAG pulse laser welding of titanium alloy (TA6V). The filet welding has different heterogeneities (microstructural and mechanical). In fact, the temperature causes microstructural changes (phase transformations, precipitations) and modifies the mechanical properties. Thermomechanical modelling has thus to be established for the welding of TA6V. (author)

  5. Well-posedness of a thermo-mechanical model for shape memory alloys under tension

    Czech Academy of Sciences Publication Activity Database

    Krejčí, Pavel; Stefanelli, U.

    2010-01-01

    Roč. 44, č. 6 (2010), s. 1239-1253 ISSN 0764-583X R&D Projects: GA ČR GAP201/10/2315 Institutional research plan: CEZ:AV0Z10190503 Keywords : shape memory alloys * thermo-mechanics * well-posedness * hysteresis operator Subject RIV: BA - General Mathematics Impact factor: 1.202, year: 2010 http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8129335

  6. Wood-plastic composites using thermomechanical pulp made from oxalic acid-pretreated red pine chips

    Science.gov (United States)

    J.E. Winandy; N.M. Stark; E. Horn

    2008-01-01

    The characteristics and properties of wood fiber is one of many factors of critical importance to the performance of wood-plastic composites. In commercial thermo-mechanical pulping (TMP) of wood chips to produce fibers, high temperatures (>100°C) are used to separate the fibers during TMP refining. These mechanical pressures and temperatures are usually modulated...

  7. Thermomechanical behavior and modeling of zircaloy cladding tubes from an unirradiated state to high burn-up

    International Nuclear Information System (INIS)

    Schaeffler-Le Pichon, I.; Geyer, P.; Bouffioux, P.

    1997-01-01

    Creep laws are nowadays commonly used to simulate the fuel rod response to the solicitations it faces during its life. These laws are sufficient for describing the base operating conditions (where only creep appears), but they have to be improved for power ramp conditions (where hardening and relaxation appear). The modification due to a neutronic irradiation of the thermomechanical behavior of stress-relieved Zircaloy 4 fuel tubes that have been analysed for five different fluences ranging from a non-irradiated material to a material for which the combustion rate was very high is presented. In the second part, a viscoplastic model able to simulate, for different isotherms, out-of-flux anisotropic mechanical behavior of the cladding tubes irradiated until high burn-up is proposed. Finally, results of numerical simulations show the ability of the model to reproduce the totality of the thermomechanical experiments. (author)

  8. Thermomechanical evaluation of the fuel assemblies fabricated in the ININ; Evaluacion termomecanica de los ensambles combustibles fabricados en el ININ

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez L, H.; Ortiz V, J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2005-07-01

    The pilot plant of fuel production of the National Institute of Nuclear Research (ININ) provided to the Laguna Verde Nuclear Power Plant (CNLV) four fuel assemblies type GE9B. The fuel irradiation was carried out in the unit 1 of the CNLV during four operation cycles, highlighting the fact that in their third cycle the four assemblies were placed in the center of the reactor core. In the Nuclear Systems Department (DSN) of the ININ it has been carried out studies to evaluate their neutron performance and to be able to determine the exposure levels of this fuels. Its also outlines the necessity to carry out a study of the thermomechanical behavior of the fuel rods that compose the assemblies, through computational codes that simulate their performance so much thermal as mechanical. For such purpose has been developing in the DSN the FETMA code, together with the codes that compose the system Fuel Management System (FMS), which evaluates the thermomechanical performance of fuel elements. In this work were used the FETMA and FEMAXI codes (developed by JAERI) to study the thermomechanical performance of the fuel elements manufactured in the ININ. (Author)

  9. Inorganic fullerene-like IF-WS{sub 2}/PVB nanocomposites of improved thermo-mechanical and tribological properties

    Energy Technology Data Exchange (ETDEWEB)

    Simić, Danica [Military Technical Institute, Ratka Resanovića 1, 11132 Belgrade (Serbia); Stojanović, Dušica B., E-mail: duca@tmf.bg.ac.rs [University of Belgrade, Faculty of Technology and Metallurgy, 11120 Belgrade (Serbia); Kojović, Aleksandar [University of Belgrade, Faculty of Technology and Metallurgy, 11120 Belgrade (Serbia); Dimić, Mirjana; Totovski, Ljubica [Military Technical Institute, Ratka Resanovića 1, 11132 Belgrade (Serbia); Uskoković, Petar S.; Aleksić, Radoslav [University of Belgrade, Faculty of Technology and Metallurgy, 11120 Belgrade (Serbia)

    2016-12-01

    The subject of this research is to explore the possibility of preparation of nanocomposite material of improved thermo-mechanical and tribological properties, using inorganic fullerene-like tungsten disulfide nanostructures (IF-WS{sub 2}) as reinforcement in poly(vinyl butyral) (PVB). This paper also reports investigation of the effects of using different solvents in preparation of PVB/IF-WS{sub 2} nanocomposite on the thermo-mechanical behavior of the resulting material. PVB was dissolved in ethanol, isopropanol, n-butanol and ethyl acetate. IF-WS{sub 2} nanoparticles were added to these PVB solutions and dispersed by different deagglomeration techniques. Samples were dried and thin films were obtained. Their microstructure and the quality of IF-WS{sub 2} dispersion and deagglomeration in PVB matrix was analyzed by scanning electron microscope (SEM). The reinforcing effect of IF-WS{sub 2} is examined by determining hardness, reduced modulus of elasticity and coefficient of friction, by nanoindentation and nanoscratch test, in terms of the different solvents applied in preparation of the samples, mode of stirring and different contents of IF-WS{sub 2}. The glass transition temperature (T{sub g}) was determined for the prepared samples using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA). Storage modulus and mechanical loss factor were observed in a defined temperature range using DMA. - Highlights: • Poly(vinyl butyral)/tungsten disulfide nanocomposites were examined. • Different solvents and deagglomeration methods affect the properties of composites. • Nanoindentation and scratch test, PSD, SEM, DSC and DMTA were analyzed. • Thermo-mechanical and antifriction properties of composite material are improved.

  10. Fully solar-driven thermo- and electrochemistry for advanced oxidation processes (STEP-AOPs) of 2-nitrophenol wastewater.

    Science.gov (United States)

    Nie, Chunhong; Shao, Nan; Wang, Baohui; Yuan, Dandan; Sui, Xin; Wu, Hongjun

    2016-07-01

    The STEP (Solar Thermal Electrochemical Process) for Advanced Oxidation Processes (AOPs, combined to STEP-AOPs), fully driven by solar energy without the input of any other forms of energy and chemicals, is introduced and demonstrated from the theory to experiments. Exemplified by the persistent organic pollutant 2-nitrophenol in water, the fundamental model and practical system are exhibited for the STEP-AOPs to efficiently transform 2-nitrophenol into carbon dioxide, water, and the other substances. The results show that the STEP-AOPs system performs more effectively than classical AOPs in terms of the thermodynamics and kinetics of pollutant oxidation. Due to the combination of solar thermochemical reactions with electrochemistry, the STEP-AOPs system allows the requisite electrolysis voltage of 2-nitrophenol to be experimentally decreased from 1.00 V to 0.84 V, and the response current increases from 18 mA to 40 mA. STEP-AOPs also greatly improve the kinetics of the oxidation at 30 °C and 80 °C. As a result, the removal rate of 2-nitrophenol after 1 h increased from 19.50% at 30 °C to 32.70% at 80 °C at constant 1.90 V. Mechanistic analysis reveals that the oxidation pathway is favorably changed because of thermal effects. The tracking of the reaction displayed that benzenediol and hydroquinone are initial products, with maleic acid and formic acid as sequential carboxylic acid products, and carbon dioxide as the final product. The theory and experiments on STEP-AOPs system exemplified by the oxidation of 2-nitrophenol provide a broad basis for extension of the STEP and AOPs for rapid and efficient treatment of organic wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Instrumentation requirements for the ESF thermomechanical experiments

    International Nuclear Information System (INIS)

    Pott, J.; Brechtel, C.E.

    1992-01-01

    In situ thermomechanical experiments are planned as part of the Yucca Mountain Site Characterization Project that require instruments to measure stress and displacement at temperatures that exceed the typical specifications of existing geotechnical instruments. A high degree of instrument reliability will also be required to satisfy the objectives of the experiments, therefore a study was undertaken to identify areas where improvement in instrument performance was required. A preliminary list of instruments required for the experiments was developed, based on existing test planning and analysis. Projected temperature requirements were compared to specifications of existing instruments to identify instrumentation development needs. Different instrument technologies, not currently employed in geotechnical instrumentation, were reviewed to identify potential improvements of existing designs for the high temperature environment. Technologies with strong potentials to improve instrument performance with relatively high reliability include graphite fiber composite materials, fiber optics, and video imagery

  12. Multi-Step Deep Reactive Ion Etching Fabrication Process for Silicon-Based Terahertz Components

    Science.gov (United States)

    Jung-Kubiak, Cecile (Inventor); Reck, Theodore (Inventor); Chattopadhyay, Goutam (Inventor); Perez, Jose Vicente Siles (Inventor); Lin, Robert H. (Inventor); Mehdi, Imran (Inventor); Lee, Choonsup (Inventor); Cooper, Ken B. (Inventor); Peralta, Alejandro (Inventor)

    2016-01-01

    A multi-step silicon etching process has been developed to fabricate silicon-based terahertz (THz) waveguide components. This technique provides precise dimensional control across multiple etch depths with batch processing capabilities. Nonlinear and passive components such as mixers and multipliers waveguides, hybrids, OMTs and twists have been fabricated and integrated into a small silicon package. This fabrication technique enables a wafer-stacking architecture to provide ultra-compact multi-pixel receiver front-ends in the THz range.

  13. Neptunium control in co-decontamination step of purex process

    International Nuclear Information System (INIS)

    Zhang Zefu; He Jianyu; Zhu Zhaowu; Ye Guoan; Zhao Zhiqiang

    2002-01-01

    A new alternative method for separation of Np in the first co-decontamination step is proposed. It comprises two steps, namely, preconditioning of Np valence state in the dissolved solution of spent fuel by NO gas bubbling in HNO 3 medium to produce HNO 2 , which is considered as salt-free process to convert Np(VI) to Np(V) and stabilization of Np(V) with urea, finally, the demonstrative counter current cascade extraction of Np(IV) and Np(V) in a miniature mixer-settler was carried out. The batch experiments show that Np(V) produced after conditioning may be slowly oxidized again to Np(VI) during standing time. Addition of urea in the HNO 3 solution might enhance the stability of Np(V). On the other hand, the solvent extraction by 30% TBP/kerosene could greatly accelerate the oxidation rate of Np(V). The chemical flow sheet study at 25degC shows that, more than 98% of Np could be routed into HLLW if urea is added in the HNO 3 solution. The operating temperature has great influence on the kinetics of Np(V) oxidation. If operation temperature races to 36degC and urea is not added, about 38% of Np will go along with U and Pu into organic phase. The behavior of Np(IV) during extraction shows great accumulation in the middle stages of battery. (author)

  14. Atomistic simulation of solid solution hardening in Mg/Al alloys: Examination of composition scaling and thermo-mechanical relationships

    International Nuclear Information System (INIS)

    Yi, Peng; Cammarata, Robert C.; Falk, Michael L.

    2016-01-01

    Dislocation mobility in a solid solution was studied using atomistic simulations of an Mg/Al system. The critical resolved shear stress (CRSS) for the dislocations on the basal plane was calculated at temperatures from 0 K to 500 K with solute concentrations from 0 to 7 at%, and with four different strain rates. Solute hardening of the CRSS is decomposed into two contributions: one scales with c 2/3 , where c is the solute concentration, and the other scales with c 1 . The former was consistent with the Labusch model for local solute obstacles, and the latter was related to the athermal plateau stress due to the long range solute effect. A thermo-mechanical model was then used to analyze the temperature and strain rate dependences of the CRSS, and it yielded self-consistent and realistic results. The scaling laws were confirmed and the thermo-mechanical model was successfully parameterized using experimental measurements of the CRSS for Mg/Al alloys under quasi-static conditions. The predicted strain rate sensitivity from the experimental measurements of the CRSS is in reasonable agreement with separate mechanical tests. The concentration scaling and the thermo-mechanical relationships provide a potential tool to analytically relate the structural and thermodynamic parameters on the microscopic level with the macroscopic mechanical properties arising from dislocation mediated deformation.

  15. Two step esterification-transesterification process of wet greasy sewage sludge for biodiesel production.

    Science.gov (United States)

    Urrutia, C; Sangaletti-Gerhard, N; Cea, M; Suazo, A; Aliberti, A; Navia, R

    2016-01-01

    Sewage sludge generated in municipal wastewater treatment plants was used as a feedstock for biodiesel production via esterification/transesterification in a two-step process. In the first esterification step, greasy and secondary sludge were tested using acid and enzymatic catalysts. The results indicate that both catalysts performed the esterification of free fatty acids (FFA) simultaneously with the transesterification of triacylglycerols (TAG). Acid catalyst demonstrated better performance in FFA esterification compared to TAG transesterification, while enzymatic catalyst showed the ability to first hydrolyze TAG in FFA, which were esterified to methyl esters. In addition, FAME concentration using greasy sludge were higher (63.9% and 58.7%), compared with those of secondary sludge (11% and 16%), using acid and enzymatic catalysts, respectively. Therefore, only greasy sludge was used in the second step of alkaline transesterification. The alkaline transesterification of the previously esterified greasy sludge reached a maximum FAME concentration of 65.4% when using acid catalyst. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Application of a unified fatigue modelling to some thermomechanical fatigue problems

    International Nuclear Information System (INIS)

    Dang, K. van; Maitournam, H.; Moumni, Z.

    2005-01-01

    Fatigue under thermomechanical loadings is an important topic for nuclear industries. For instance, thermal fatigue cracking is observed in the mixing zones of the nuclear reactor. Classical computations using existing methods based on strain amplitude or fracture mechanics are not sufficiently predictive. In this paper an alternative approach is proposed based on a multiscale modelling thanks to shakedown hypothesis. Examples of predictive results are presented. Finally an application to the RHR problem is discussed. Main ideas of the fatigue modelling: Following an idea of Professor D. Drucker who wrote in 1963 'when applied to the microstructure there is a hope that the concept of endurance limit and shakedown are related, and that fatigue failure can be related to energy dissipated in idealized material when shakedown does not occur.' we have developed a theory of fatigue based on this concept which is different from classical fatigue approaches. Many predictive applications have been already done particularly for the automotive industry. Fatigue resistance of structures undergoing thermomechanical loadings in the high cycle regime as well as in the low cycle regime are calculated using this modelling. However, this fatigue theory is until now rarely used in nuclear engineering. After recalling the main points of the theory, we shall present some relevant applications which were done in different industrial sectors. We shall apply this modelling to the prediction of thermal cracking observed in the mixing zones of RHR. (authors)

  17. Microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the two-step sintering process

    International Nuclear Information System (INIS)

    Lu, X.Y.; Nagata, A.; Sugawara, K.

    2008-01-01

    The microstructure and superconducting properties of Bi-2223/Ag tapes fabricated in the two-step sintering process were investigated. The tapes were then subjected to two heat treatments with an intermediate rolling. All the tapes were sintered at 835 deg. C for 24 h at initial sintering stage. A two-step sintering procedure was then used in the final sintering stage. In the first step, the tapes are sintered at 840-865 deg. C for 1 h. In the second step, they were sintered at 835 deg. C for 120 h. The results show that the first step sintering temperature has significant influence on the microstructure and the critical current density J c . The observed microstructures are consistent well with the different J c performances of the tapes first-step-sintered at different temperatures. The tape first-step-sintered at 850 deg. C, which has small secondary phases, stronger c-axis grain alignment, higher proportion of Bi-2223 phase, and no cracks, exhibits the highest J c value

  18. Thermomechanical fatigue of shape memory alloys

    International Nuclear Information System (INIS)

    Lagoudas, D C; Kumar, P K; Miller, D A; Rong, L

    2009-01-01

    As shape memory alloys (SMAs) gain popularity as high energy density actuators, one characteristic that becomes particularly important is the thermomechanical transformation fatigue life, in addition to maximum transformation strain and stability of actuation cycles. In this paper, a novel test frame design and testing protocol are discussed, for investigating the thermally activated transformation fatigue characteristics of SMAs under various applied loads for both complete and partial phase transformation. A Ni 50 Ti 40 Cu 10 (at.%) SMA was chosen for this investigation and the effects of various heat treatments on the transformation temperatures and the transformation fatigue lives of actuators were studied. For selected heat treatments, the evolution of recoverable and irrecoverable strains up to failure under different applied stress levels was studied in detail. The influence of complete and partial transformation on the fatigue life is also presented. The irrecoverable strain accumulation as a function of the number of cycles to failure for different stress levels is presented by a relationship similar to the Manson–Coffin law for both partial and complete transformations

  19. Thermomechanical scoping calculations for the waste package environment tests

    International Nuclear Information System (INIS)

    Butkovich, T.R.; Yow, J.L. Jr.

    1986-03-01

    During the site characterization phase of the Nevada Nuclear Waste Storage Investigation Project, tests are planned to provide field information on the hydrological and thermomechanical environment. These results are needed for assessing performance of stored waste packages emplaced at depth in excavations in a rock mass. Scoping calculations were performed to provide information on displacements and stress levels attained around excavations in the rock mass from imposing a thermal load designed to simulate the heat produced by radioactive decay. In this way, approximate levels of stresses and displacements are available for choosing instrumentation type and sensitivity as well as providing indications for optimizing instrument emplacement during the test. 7 refs., 9 figs., 1 tab

  20. On the thermomechanical deformation of silver shape memory nanowires

    International Nuclear Information System (INIS)

    Park, Harold S.; Ji, Changjiang

    2006-01-01

    We present an analysis of the uniaxial thermomechanical deformation of single-crystal silver shape memory nanowires using atomistic simulations. We first demonstrate that silver nanowires can show both shape memory and pseudoelastic behavior, then perform uniaxial tensile loading of the shape memory nanowires at various deformation temperatures, strain rates and heat transfer conditions. The simulations show that the resulting mechanical response of the shape memory nanowires depends strongly upon the temperature during deformation, and can be fundamentally different from that observed in bulk polycrystalline shape memory alloys. The energy and temperature signatures of uniaxially loaded silver shape memory nanowires are correlated to the observed nanowire deformation, and are further discussed in comparison to bulk polycrystalline shape memory alloy behavior

  1. Noise Suppression in ECG Signals through Efficient One-Step Wavelet Processing Techniques

    Directory of Open Access Journals (Sweden)

    E. Castillo

    2013-01-01

    Full Text Available This paper illustrates the application of the discrete wavelet transform (DWT for wandering and noise suppression in electrocardiographic (ECG signals. A novel one-step implementation is presented, which allows improving the overall denoising process. In addition an exhaustive study is carried out, defining threshold limits and thresholding rules for optimal wavelet denoising using this presented technique. The system has been tested using synthetic ECG signals, which allow accurately measuring the effect of the proposed processing. Moreover, results from real abdominal ECG signals acquired from pregnant women are presented in order to validate the presented approach.

  2. Role of step stiffness and kinks in the relaxation of vicinal (001) with zigzag [110] steps

    Science.gov (United States)

    Mahjoub, B.; Hamouda, Ajmi BH.; Einstein, TL.

    2017-08-01

    We present a kinetic Monte Carlo study of the relaxation dynamics and steady state configurations of 〈110〉 steps on a vicinal (001) simple cubic surface. This system is interesting because 〈110〉 (fully kinked) steps have different elementary excitation energetics and favor step diffusion more than 〈100〉 (nominally straight) steps. In this study we show how this leads to different relaxation dynamics as well as to different steady state configurations, including that 2-bond breaking processes are rate determining for 〈110〉 steps in contrast to 3-bond breaking processes for 〈100〉-steps found in previous work [Surface Sci. 602, 3569 (2008)]. The analysis of the terrace-width distribution (TWD) shows a significant role of kink-generation-annihilation processes during the relaxation of steps: the kinetic of relaxation, toward the steady state, is much faster in the case of 〈110〉-zigzag steps, with a higher standard deviation of the TWD, in agreement with a decrease of step stiffness due to orientation. We conclude that smaller step stiffness leads inexorably to faster step dynamics towards the steady state. The step-edge anisotropy slows the relaxation of steps and increases the strength of step-step effective interactions.

  3. Improvement of high-temperature thermomechanical treatment of the rolled section made of VT3-1 alloy

    International Nuclear Information System (INIS)

    Gavze, A.L.; Korostelev, Yu.P.

    2002-01-01

    Changes in mechanical properties and structure are investigated in alloy VT3-1 rods produced with the use of high temperature thermomechanical treatment (HTMT) on their heating and deformation during straightening as well as during preliminary hot deformation of the billets on a helical rolling mill (HRM). It is stated that the straightening at 550-700 deg C with elongation of ∼ 2% results in some decrease of ultimate strength and in essential enhancement of plasticity and impact strength. In a similar manner, preliminary rolling on HRM affects the properties of rods after final heat treatment. It is shown that rod production according to the experimental processing procedure increases the quality of the rods and can be realized when manufacturing rolled products of alloy VT3-1 with the use of HTMT [ru

  4. On phase transformation models for thermo-mechanically coupled response of Nitinol

    KAUST Repository

    Sengupta, Arkaprabha

    2011-03-31

    Fully coupled thermomechanical models for Nitinol at the grain level are developed in this work to capture the inter-dependence between deformation and temperature under non-isothermal conditions. The martensite transformation equations are solved using a novel algorithm which imposes all relevant constraints on the volume fractions. The numerical implementation of the resulting models within the finite element method is effected by the monolithic solution of the momentum and energy equations. Validation of the models is achieved by means of thin-tube experiments at different strain rates. © 2011 Springer-Verlag.

  5. Recyclable crosslinked polymer networks with full property recovery made via one-step controlled radical polymerization

    Science.gov (United States)

    Jin, Kailong; Li, Lingqiao; Torkelson, John

    Rubber tires illustrate well the issues ranging from economic loss to environmental problems and sustainability issues that arise with spent, covalently crosslinked polymers. A nitroxide-mediated polymerization (NMP) strategy has been developed that allows for one-step synthesis of recyclable crosslinked polymers from monomers or polymers that contain carbon-carbon double bonds amenable to radical polymerization. Resulting materials possess dynamic alkoxyamine crosslinks that undergo reversible decrosslinking as a function of temperature. Using polybutadiene as starting material, and styrene, an appropriate nitroxide molecule and bifunctional initiator for initial crosslinking, a model for tire rubber can be produced by reaction at temperatures comparable to those employed in tire molding. Upon cooling, the crosslinks are made permanent due to the extraordinarily strong temperature dependence of the reverisible nitroxide capping and uncapping reaction. Based on thermomechanical property characterization, when the original crosslinked model rubber is chopped into bits and remolded in the melt state, a well-consolidated material is obtained which exhibits full recovery of properties reflecting crosslink density after multiple recycling steps.

  6. Service life prediction. Development of models for predicting the service life of power plant components subject to thermomechanical creep fatigue; Lebensdauervorhersage. Entwicklung von Modellen zur Lebensdauervorhersage von Kraftwerksbauteilen unter thermisch-mechanischer Kriechermuedungsbeanspruchung. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Cui, L.; Scholz, A. [Technische Univ. Darmstadt (Germany). Institut fuer Werkstoffkunde; Hartrott, P. von; Schlesinger, M. [Fraunhofer-Institut fuer Werkstoffmechanik (IWM), Freiburg im Breisgau (Germany)

    2009-07-01

    Extensive use is made of massive components of heat resistant and highly heat resistant materials in installations of the power and heating industry. These components are exposed to varying thermomechanical stress as a result of ramping-up and down processes. In this research project two computer-assisted methods of predicting service life until crack initiation were extended to include cases of thermomechanical multi-axis stress conducive to creep fatigue and of superposition of high-cycle stress on power plant components. Investigations were limited to rotor steel of type X12CrMoWVNbN10-1-1. Complex thermomechanical multi-axis experiments were performed on round, notched and cruciform test specimens of close-to-life dimensions in order to demonstrate by experiment the validity of these models. The results of these calculations showed an acceptable degree of agreement between experiment and simulation for both models. Calculations on earlier TMF experiments performed at IfW on hollow specimens of 1%CrMoNiV showed good predictability for both the SARA and the ThoMat programme. Calculations on experiments performed at MPA Stuttgart on model bodies consisting of the same 1%CrMoNiV showed a predictability of acceptable variability considering the complexity of the stresses involved. A further outcome of this project is that the use of SARA appears universally suitable for the construction of new plants and in the service area, while the use of ThoMat appears suited for detail optimisation in the development process.

  7. Aerospace Materials Process Modelling

    Science.gov (United States)

    1988-08-01

    Cooling Transformation diagram ( CCT diagram ) When a IT diagram is used in the heat process modelling, we suppose that a sudden cooling (instantaneous...processes. CE, chooses instead to study thermo-mechanical properties referring to a CCT diagram . This is thinked to be more reliable to give a true...k , mm-_____sml l ml A I 1 III 12.4 This determination is however based on the following approximations: i) A CCT diagram is valid only for the

  8. Controllable 3D architectures of aligned carbon nanotube arrays by multi-step processes

    Science.gov (United States)

    Huang, Shaoming

    2003-06-01

    An effective way to fabricate large area three-dimensional (3D) aligned CNTs pattern based on pyrolysis of iron(II) phthalocyanine (FePc) by two-step processes is reported. The controllable generation of different lengths and selective growth of the aligned CNT arrays on metal-patterned (e.g., Ag and Au) substrate are the bases for generating such 3D aligned CNTs architectures. By controlling experimental conditions 3D aligned CNT arrays with different lengths/densities and morphologies/structures as well as multi-layered architectures can be fabricated in large scale by multi-step pyrolysis of FePc. These 3D architectures could have interesting properties and be applied for developing novel nanotube-based devices.

  9. Rheological, thermo-mechanical, and baking properties of wheat-millet flour blends.

    Science.gov (United States)

    Aprodu, Iuliana; Banu, Iuliana

    2015-07-01

    Millet has long been known as a good source of fiber and antioxidants, but only lately started to be exploited by food scientists and food industry as a consequence of increased consumer awareness. In this study, doughs and breads were produced using millet flour in different ratios (10, 20, 30, 40, and 50%) to white, dark, and whole wheat flour. The flour blends were evaluated in terms of rheological and thermo-mechanical properties. Fundamental rheological measurements revealed that the viscosity of the flour formulations increases with wheat flour-extraction rate and decreases with the addition of millet flour. Doughs behavior during mixing, overmixing, pasting, and gelling was established using the Mixolab device. The results of this bread-making process simulation indicate that dough properties become critical for the flour blends with millet levels higher than 30%. The breads were evaluated for volume, texture, and crumb-grain characteristics. The baking test and sensory evaluation results indicated that substitution levels of up to 30% millet flour could be used in composite bread flour. High levels of millet flour (40 and 50%) negatively influenced the loaf volume, crumb texture, and taste. © The Author(s) 2014.

  10. Effects of silicon and thermo-mechanical process on microstructure and properties of Cu–10Ni–3Al–0.8Si alloy

    International Nuclear Information System (INIS)

    Shen, Leinuo; Li, Zhou; Zhang, Zheming; Dong, Qiyi; Xiao, Zhu; Lei, Qian; Qiu, Wenting

    2014-01-01

    Highlights: • Cu–10Ni–3Al–0.8Si alloy with ultra-high strength was designed. • The addition of silicon hindered the precipitation of large NiAl phase. • Tensile strength and electrical conductivity were 1180 MPa and 18.1% IACS. • Nano-scale Ni 2 Si and Ni 3 Al improved the strength and electrical conductivity. - Abstract: Cu–10Ni–3Al–0.8Si alloy with ultra-high strength was designed and its microstructure was studied using optical microscopy, scanning electron microscopy, transmission electron microscopy. The alloy went through a set of thermo-mechanical process: solution treated at 950 °C for 4 h, then cold-rolled by 50% and aged at 450 °C for 8 h, followed by 60% cold-rolling and aging at 450 °C for 8 h. After these treatment, the tensile strength was 1180 MPa, yield strength was 1133 MPa and electrical conductivity was 18.1% IACS, respectively. The comprehensive properties, especially the electrical conductivity of the designed alloy, were much higher than those of traditional Cu–Ni–Al alloys. The addition of silicon in the designed alloy hindered the precipitation of large-scale NiAl phase and improved the strength of the alloy. The orientation relationships between δ-Ni 2 Si, Ni 3 Al precipitates and copper matrix were: [001] Cu ‖[001] Ni 3 Al ‖[001] δ ,(110) Cu ‖(110) Ni 3 Al ‖(010) δ ,(11 ¯ 0) Cu ‖ (11 ¯ 0) Ni 3 Al ||(100) δ , respectively

  11. Critical steps in learning from incidents: using learning potential in the process from reporting an incident to accident prevention.

    Science.gov (United States)

    Drupsteen, Linda; Groeneweg, Jop; Zwetsloot, Gerard I J M

    2013-01-01

    Many incidents have occurred because organisations have failed to learn from lessons of the past. This means that there is room for improvement in the way organisations analyse incidents, generate measures to remedy identified weaknesses and prevent reoccurrence: the learning from incidents process. To improve that process, it is necessary to gain insight into the steps of this process and to identify factors that hinder learning (bottlenecks). This paper presents a model that enables organisations to analyse the steps in a learning from incidents process and to identify the bottlenecks. The study describes how this model is used in a survey and in 3 exploratory case studies in The Netherlands. The results show that there is limited use of learning potential, especially in the evaluation stage. To improve learning, an approach that considers all steps is necessary.

  12. Analysis of the finite deformation response of shape memory polymers: I. Thermomechanical characterization

    International Nuclear Information System (INIS)

    Volk, Brent L; Lagoudas, Dimitris C; Chen, Yi-Chao; Whitley, Karen S

    2010-01-01

    This study presents the analysis of the finite deformation response of a shape memory polymer (SMP). This two-part paper addresses the thermomechanical characterization of SMPs, the derivation of material parameters for a finite deformation phenomenological model, the numerical implementation of such a model, and the predictions from the model with comparisons to experimental data. Part I of this work presents the thermomechanical characterization of the material behavior of a shape memory polymer. In this experimental investigation, the vision image correlation system, a visual–photographic apparatus, was used to measure displacements in the gauge area. A series of tensile tests, which included nominal values of the extension of 10%, 25%, 50%, and 100%, were performed on SMP specimens. The effects on the free recovery behavior of increasing the value of the applied deformation and temperature rate were considered. The stress–extension relationship was observed to be nonlinear for increasing values of the extension, and the shape recovery was observed to occur at higher temperatures upon increasing the temperature rate. The experimental results, aided by the advanced experimental apparatus, present components of the material behavior which are critical for the development and calibration of models to describe the response of SMPs

  13. Free-form processing of near-net shapes using directed light fabrication

    International Nuclear Information System (INIS)

    Thoma, D.J.; Lewis, G.K.; Milewski, J.O.; Nemec, R.B.

    1997-05-01

    Directed light fabrication (DLF) is a rapid fabrication process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, near-net shape, three-dimensional metal components from a computer generated solid model. Computer controls dictate the metal deposition pathways, and no preforms or molds are required to generate complex sample geometries with accurate and precise tolerances. The DLF technique offers unique advantages over conventional thermomechanical processes or thermal spray processes in that many labor and equipment intensive steps can be avoided to produce components with fully dense microstructures. Moreover, owing to the flexibility in power distributions of lasers, a variety of materials have been processed, ranging from aluminum alloys to tungsten, and including intermetallics such as Mo 5 Si 3 . Since DLF processing offers unique capabilities and advantages for the rapid fabrication of complex metal components, an examination of the microstructural development has been performed in order to define and optimize the processed materials. Solidification studies of DLF processing have demonstrated that a continuous liquid/solid interface is maintained while achieving high constant cooling rates that can be varied between 10 to 10 5 K s -1 and solidification growth rates ranging up to the 10 -2 m s -1

  14. Fostering Autonomy through Syllabus Design: A Step-by-Step Guide for Success

    Science.gov (United States)

    Ramírez Espinosa, Alexánder

    2016-01-01

    Promoting learner autonomy is relevant in the field of applied linguistics due to the multiple benefits it brings to the process of learning a new language. However, despite the vast array of research on how to foster autonomy in the language classroom, it is difficult to find step-by-step processes to design syllabi and curricula focused on the…

  15. Lithosphere tectonics and thermo-mechanical properties: An integrated modeling approach for enhanced geothermal systems exploration in Europe

    NARCIS (Netherlands)

    Wees, J.D. van; Cloetingh, S.; Ziegler, P.A.; Lenkey, L.; Beekman, F.; Tesauro, M.; Förster, A.; Norden, B.; Kaban, M.; Hardebol, N.; Voorde, M.T.; Willingshofer, E.; Cornu, T.; Bonté, D.

    2009-01-01

    For geothermal exploration and the development of enhanced geothermal systems (EGS) knowlegde of temperature at drillable depth is a prerequisite for site selection. Equally important is the thermo-mechanical signature of the lithosphere and crust which allow to obtain critical constraints for the

  16. Fluka and thermo-mechanical studies for the CLIC main dump

    CERN Document Server

    Mereghetti, Alessio; Vlachoudis, Vasilis

    2011-01-01

    In order to best cope with the challenge of absorbing the multi-MW beam, a water beam dump at the end of the CLIC post-collision line has been proposed. The design of the dump for the Conceptual Design Report (CDR) was checked against with a set of FLUKA Monte Carlo simulations, for the estimation of the peak and total power absorbed by the water and the vessel. Fluence spectra of escaping particles and activation rates of radio-nuclides were computed as well. Finally, the thermal transient behavior of the water bath and a thermo-mechanical analysis of the preliminary design of the window were done.

  17. Processing of fine grained AISI 304L austenitic stainless steel by cold rolling and high-temperature short-term annealing

    Science.gov (United States)

    Naghizadeh, Meysam; Mirzadeh, Hamed

    2018-05-01

    An advanced thermomechanical process based on the formation and reversion of deformation-induced martensite was used to refine the grain size and enhance the hardness of an AISI 304L austenitic stainless steel. Both low and high reversion annealing temperatures and also the repetition of the whole thermomechanical cycle were considered. While a microstructure with average austenite grain size of a few micrometers was achieved based on cold rolling and high-temperature short-term annealing, an extreme grain refinement up to submicrometer regime was obtained by cold rolling followed by low-temperature long-term annealing. However, the required annealing time was found to be much longer, which negates its appropriateness for industrial production. While a magnificent grain refinement was achieved by one pass of the high-temperature thermomechanical process, the reduction in grain size was negligible by the repetition of the whole cycle. It was found that the hardness of the thermomechanically processed material is much higher than that of the as-received material. The results of the present work were shown to be compatible with the general trend of grain size dependence of hardness for AISI 304L stainless steel based on the Hall-Petch relationship. The results were also discussed based on the X-ray evaluation of dislocation density by modified Williamson-Hall plots.

  18. Thermo-mechanical constitutive modeling of unsaturated clays based on the critical state concepts

    OpenAIRE

    Tourchi, Saeed; Hamidi, Amir

    2015-01-01

    A thermo-mechanical constitutive model for unsaturated clays is constructed based on the existing model for saturated clays originally proposed by the authors. The saturated clays model was formulated in the framework of critical state soil mechanics and modified Cam-clay model. The existing model has been generalized to simulate the experimentally observed behavior of unsaturated clays by introducing Bishop's stress and suction as independent stress parameters and modifying the hardening rul...

  19. Modelling of Sub-daily Hydrological Processes Using Daily Time-Step Models: A Distribution Function Approach to Temporal Scaling

    Science.gov (United States)

    Kandel, D. D.; Western, A. W.; Grayson, R. B.

    2004-12-01

    Mismatches in scale between the fundamental processes, the model and supporting data are a major limitation in hydrologic modelling. Surface runoff generation via infiltration excess and the process of soil erosion are fundamentally short time-scale phenomena and their average behaviour is mostly determined by the short time-scale peak intensities of rainfall. Ideally, these processes should be simulated using time-steps of the order of minutes to appropriately resolve the effect of rainfall intensity variations. However, sub-daily data support is often inadequate and the processes are usually simulated by calibrating daily (or even coarser) time-step models. Generally process descriptions are not modified but rather effective parameter values are used to account for the effect of temporal lumping, assuming that the effect of the scale mismatch can be counterbalanced by tuning the parameter values at the model time-step of interest. Often this results in parameter values that are difficult to interpret physically. A similar approach is often taken spatially. This is problematic as these processes generally operate or interact non-linearly. This indicates a need for better techniques to simulate sub-daily processes using daily time-step models while still using widely available daily information. A new method applicable to many rainfall-runoff-erosion models is presented. The method is based on temporal scaling using statistical distributions of rainfall intensity to represent sub-daily intensity variations in a daily time-step model. This allows the effect of short time-scale nonlinear processes to be captured while modelling at a daily time-step, which is often attractive due to the wide availability of daily forcing data. The approach relies on characterising the rainfall intensity variation within a day using a cumulative distribution function (cdf). This cdf is then modified by various linear and nonlinear processes typically represented in hydrological and

  20. The typical steps of radiation processes development. Experience in investigation, designing and application

    International Nuclear Information System (INIS)

    Babkin, I. Yu.

    1983-01-01

    The typical steps of radiation processes development are discussed as: primary laboratory investigations; primary economic evaluation; more exact estimation of situation in industry; comparative analysis; development of a flow sheet; pilot plant; obtaining of initial data for designing of industrial scale plant; prediction of industrial situation; designing of semi-industrial or industrial plant; industrial plant. (U.K.)

  1. The Mixing of Methods: a three-step process for improving rigour in impact evaluations

    NARCIS (Netherlands)

    Ton, G.

    2012-01-01

    This article describes a systematic process that is helpful in improving impact evaluation assignments, within restricted budgets and timelines. It involves three steps: a rethink of the key questions of the evaluation to develop more relevant, specific questions; a way of designing a mix of

  2. Thermomechanical modeling of the Spent Fuel Test-Climax

    Energy Technology Data Exchange (ETDEWEB)

    Butkovich, T.R.; Patrick, W.C.

    1986-02-01

    The Spent Fuel Test-Climax (SFT-C) was conducted to evaluate the feasibility of retrievable deep geologic storage of commercially generated spent nuclear-reactor fuel assemblies. One of the primary aspects of the test was to measure the thermomechanical response of the rock mass to the extensive heating of a large volume of rock. Instrumentation was emplaced to measure stress changes, relative motion of the rock mass, and tunnel closures during three years of heating from thermally decaying heat sources, followed by a six-month cooldown period. The calculations reported here were performed using the best available input parameters, thermal and mechanical properties, and power levels which were directly measured or inferred from measurements made during the test. This report documents the results of these calculations and compares the results with selected measurements made during heating and cooling of the SFT-C.

  3. Thermomechanical modeling of the Spent Fuel Test-Climax

    International Nuclear Information System (INIS)

    Butkovich, T.R.; Patrick, W.C.

    1986-02-01

    The Spent Fuel Test-Climax (SFT-C) was conducted to evaluate the feasibility of retrievable deep geologic storage of commercially generated spent nuclear-reactor fuel assemblies. One of the primary aspects of the test was to measure the thermomechanical response of the rock mass to the extensive heating of a large volume of rock. Instrumentation was emplaced to measure stress changes, relative motion of the rock mass, and tunnel closures during three years of heating from thermally decaying heat sources, followed by a six-month cooldown period. The calculations reported here were performed using the best available input parameters, thermal and mechanical properties, and power levels which were directly measured or inferred from measurements made during the test. This report documents the results of these calculations and compares the results with selected measurements made during heating and cooling of the SFT-C

  4. Effect of some thermomechanical variables on plastic flow and creep-rupture of type 304 stainless steel at 5930C

    International Nuclear Information System (INIS)

    Swindeman, R.W.

    1977-01-01

    As part of an effort to examine sources of variability in the creep-rupture behavior of type 304 stainless steel, specimens subjected to a variety of prior thermomechanical treatments were tested. Included were different reannealing temperatures, cooling rates, types of prior straining, and a 24-hr age at 816 0 C. Two product forms of a single heat (heat 9T2796) were involved, and most testing was at 593 0 C. For material with coarse grain size, reannealing temperature had no pronounced influence. However, slow cooling rates and the 816 0 C aging significantly extended the rupture life. On the other hand, cold working by an equivalent of 4% tensile strain had very little influence on rupture life. Slow cooling or aging increased rupture life as a result of greatly improved creep ductility. This finding is consistent with similar observations in the literature for this and other stainless steels, and is believed to be due to the development of coarse, beneficial carbides on grain boundaries before stressing. The creep response in the primary and secondary stages was influenced by nearly all the thermomechanical treatments, but the variability in the response at relatively high stresses was scarcely greater than the variability observed in multiple tests on specimens having a common thermomechanical history. 10 figures, 1 table

  5. On the Convexity of Step out - Step in Sequencing Games

    NARCIS (Netherlands)

    Musegaas, Marieke; Borm, Peter; Quant, Marieke

    2016-01-01

    The main result of this paper is the convexity of Step out - Step in (SoSi) sequencing games, a class of relaxed sequencing games first analyzed by Musegaas, Borm, and Quant (2015). The proof makes use of a polynomial time algorithm determining the value and an optimal processing order for an

  6. A novel, substrate independent three-step process for the growth of uniform ZnO nanorod arrays

    International Nuclear Information System (INIS)

    Byrne, D.; McGlynn, E.; Henry, M.O.; Kumar, K.; Hughes, G.

    2010-01-01

    We report a three-step deposition process for uniform arrays of ZnO nanorods, involving chemical bath deposition of aligned seed layers followed by nanorod nucleation sites and subsequent vapour phase transport growth of nanorods. This combines chemical bath deposition techniques, which enable substrate independent seeding and nucleation site generation with vapour phase transport growth of high crystalline and optical quality ZnO nanorod arrays. Our data indicate that the three-step process produces uniform nanorod arrays with narrow and rather monodisperse rod diameters (∼ 70 nm) across substrates of centimetre dimensions. X-ray photoelectron spectroscopy, scanning electron microscopy and X-ray diffraction were used to study the growth mechanism and characterise the nanostructures.

  7. Influence of dwell times on the thermomechanical fatigue behavior of a directionally solidified Ni-base superalloy

    Czech Academy of Sciences Publication Activity Database

    Guth, S.; Petráš, Roman; Škorík, Viktor; Kruml, Tomáš; Man, Jiří; Lang, K. H.; Polák, Jaroslav

    2015-01-01

    Roč. 80, NOV (2015), s. 426-433 ISSN 0142-1123 R&D Projects: GA MŠk(CZ) EE2.3.30.0063 Institutional support: RVO:68081723 Keywords : Nickel base superalloy * Thermomechanical fatigue * Dwell time * Lifetime behavior * Damage mechanisms Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.162, year: 2015

  8. Diffusion welding. [heat treatment of nickel alloys following single step vacuum welding process

    Science.gov (United States)

    Holko, K. H. (Inventor)

    1974-01-01

    Dispersion-strengthened nickel alloys are sanded on one side and chemically polished. This is followed by a single-step welding process wherein the polished surfaces are forced into intimate contact at 1,400 F for one hour in a vacuum. Diffusion, recrystallization, and grain growth across the original weld interface are obtained during postheating at 2,150 F for two hours in hydrogen.

  9. The effects of short-lived radionuclides and porosity on the early thermo-mechanical evolution of planetesimals

    Science.gov (United States)

    Lichtenberg, Tim; Golabek, Gregor J.; Gerya, Taras V.; Meyer, Michael R.

    2016-08-01

    The thermal history and internal structure of chondritic planetesimals, assembled before the giant impact phase of chaotic growth, potentially yield important implications for the final composition and evolution of terrestrial planets. These parameters critically depend on the internal balance of heating versus cooling, which is mostly determined by the presence of short-lived radionuclides (SLRs), such as 26Al and 60Fe, as well as the heat conductivity of the material. The heating by SLRs depends on their initial abundances, the formation time of the planetesimal and its size. It has been argued that the cooling history is determined by the porosity of the granular material, which undergoes dramatic changes via compaction processes and tends to decrease with time. In this study we assess the influence of these parameters on the thermo-mechanical evolution of young planetesimals with both 2D and 3D simulations. Using the code family I2ELVIS/I3ELVIS we have run numerous 2D and 3D numerical finite-difference fluid dynamic models with varying planetesimal radius, formation time and initial porosity. Our results indicate that powdery materials lowered the threshold for melting and convection in planetesimals, depending on the amount of SLRs present. A subset of planetesimals retained a powdery surface layer which lowered the thermal conductivity and hindered cooling. The effect of initial porosity was small, however, compared to those of planetesimal size and formation time, which dominated the thermo-mechanical evolution and were the primary factors for the onset of melting and differentiation. We comment on the implications of this work concerning the structure and evolution of these planetesimals, as well as their behavior as possible building blocks of terrestrial planets.

  10. Thermomechanical analysis of nuclear fuel elements

    International Nuclear Information System (INIS)

    Hernandez L, H.

    1997-01-01

    This work presents development of a code to obtain the thermomechanical analysis of fuel rods in the fuel assemblies inserted in the core of BWR reactors. The code uses experimental correlations developed in several laboratories. The development of the code is divided in two parts: a) the thermal part and b) the mechanical part, extending both the fuel and the cladding materials. The thermal part consists of finding the radial distribution of temperatures in the pellet, from the fuel centerline up to the coolant, along the total active length, considering one and two phase flow in the coolant, as a result of the pressure drop in the system. The mechanical part analyzes the effects of temperature gradients, pressure and irradiation, to which the fuel rod is subjected. The strains produced by swelling, creep and thermal stress in the fuel material are analyzed. In the same way the strains in the cladding are analyzed, considering the effects produced by the pressure exerted on the cladding by pellet swelling, by the pressure caused by fission gas release toward the cavities, and by the strain produced on the cladding by the pressure changes of the system. (Author)

  11. Using Aspen plus in thermodynamics instruction a step-by-step guide

    CERN Document Server

    Sandler, Stanley I

    2015-01-01

    A step-by-step guide for students (and faculty) on the use of Aspen in teaching thermodynamics Used for a wide variety of important engineering tasks, Aspen Plus software is a modeling tool used for conceptual design, optimization, and performance monitoring of chemical processes. After more than twenty years, it remains one of the most popular and powerful chemical engineering simulation programs used both industrially and academically. Using Aspen Plus in Thermodynamics Instruction: A Step by Step Guide introduces the reader to the use of Aspen Plus in courses in thermodynamics. It prov

  12. Water-cooled lithium-lead box-shaped blanket concept for Demo: thermo-mechanical optimization and manufacturing sequence proposal

    International Nuclear Information System (INIS)

    Baraer, L.; Dinot, N.; Giancarli, L.; Proust, E.; Salavy, J.F.; Severi, Y.; Quintric-Bossy, J.

    1992-01-01

    The development of the water-cooled lithium-lead box-shaped blanket concept for DEMO has now reached the stage of thermo-mechanical optimization. In the previous design phases the preliminary dimensioning of the cooling circuit has permitted to define the water proportions required in the breeder region and to demonstrate, after a minimization of steel proportion and thicknesses, that this concept could reach tritium breeding self-sufficiency. In the present analysis the location of the coolant pipes has been optimized for the whole equatorial plane cross-section of both inboard and outboard segments in order to maintain the maximum Pb-17Li/steel interface temperature below 480 deg C and to minimize the thermal gradients along the steel structures. The consequent thermo-mechanical analysis has shown that the thermal stresses always remain below the allowable limits. Segment fabricability and removal are the next design issues to be analyzed. Within this strategy, a first manufactury sequence for the outboard segment is proposed

  13. Existence and non-existence for the full thermomechanical Souza–Auricchio model of shape memory wires

    Czech Academy of Sciences Publication Activity Database

    Krejčí, Pavel; Stefanelli, U.

    2011-01-01

    Roč. 16, č. 4 (2011), s. 349-365 ISSN 1081-2865 R&D Projects: GA ČR GAP201/10/2315 Institutional research plan: CEZ:AV0Z10190503 Keywords : shape memory alloys * thermomechanics * existence result * blowup in finite time Subject RIV: BA - General Mathematics Impact factor: 1.012, year: 2011 http://mms.sagepub.com/content/early/2011/03/11/1081286510386935.abstract

  14. Existence and non-existence for the full thermomechanical Souza–Auricchio model of shape memory wires

    Czech Academy of Sciences Publication Activity Database

    Krejčí, Pavel; Stefanelli, U.

    2011-01-01

    Roč. 16, č. 4 (2011), s. 349-365 ISSN 1081-2865 R&D Projects: GA ČR GAP201/10/2315 Institutional research plan: CEZ:AV0Z10190503 Keywords : shape memory alloys * thermomechanics * existence result * blowup in finite time Subject RIV: BA - General Mathematics Impact factor: 1.012, year: 2011 http:// mms .sagepub.com/content/early/2011/03/11/1081286510386935.abstract

  15. A green two-step process for adipic acid production from cyclohexene. A study on parameters affecting selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Cavani, F.; Macchia, F.; Pino, R.; Raabova, K.; Rozhko, E. [Bologna Univ. (Italy). Dipt. di Chimica Industriale e dei Materiali; Alini, S.; Accorinti, P.; Babini, G. [Radici Chimica SpA, Novara (Italy)

    2011-07-01

    In this paper, we report about the effect of reaction parameters on catalytic behavior in a twostep process aimed at the synthesis of adipic acid from cyclohexene. In the first step, cyclohexene reacts with an aqueous solution of hydrogen peroxide, under conditions leading to the formation of trans-1,2-cyclohexandiol as the prevailing product; the reaction is catalysed by tungstic acid, in the presence of phosphoric acid and of a PT agent. In the second step, 1,2-cyclohexandiol is oxidized with air, in the presence of an heterogeneous catalyst made of alumina-supported Ru(OH){sub 3}. This process is aimed at using the minimal amount of the costly hydrogen peroxide, since only one mole is theoretically needed per mole of cyclohexene. The first step afforded very high yield to the glycol, using only a slight excess of hydrogen peroxide. However, the second step turned out to be the more critical one, since the selectivity to adipic acid was very low because of the concomitant occurrence of several undesired side reactions. The latter were in part due to the reaction conditions used, which were necessary for the activation of cyclohexandiol. (orig.)

  16. Physical Analysis of Cross-Wedge Rolling Process of a Stepped Shaft

    Directory of Open Access Journals (Sweden)

    Łukasz Wójcik

    2017-12-01

    Full Text Available The paper presents experimental- model research results on the process of cross-wedge rolling of an axially-symmetrical element (stepped shaft. During research was used plastic mass on the basis of waxes in black and white colour. The aim of this experimental research was to determine the best option of forming in terms of values obtained and the course of forces. Physical examination was carried out using specialist machines, that is model and laboratory cross-wedge rolling mill. Experimental analysis was carried out using billets with the temperature of 15°C, whereas the actual process was carried out for billet from C45 carbon steel of temperature 1150°C. The study compared the dimensions of the components obtained during rolling tests and forming forces obtained in the result of physical modeling with forces obtained during real tests.

  17. Evaluating Web-Scale Discovery Services: A Step-by-Step Guide

    Directory of Open Access Journals (Sweden)

    Joseph Deodato

    2015-06-01

    Full Text Available Selecting a web-scale discovery service is a large and important undertaking that involves a significant investment of time, staff, and resources. Finding the right match begins with a thorough and carefully planned evaluation process. In order to be successful, this process should be inclusive, goal-oriented, data-driven, user-centered, and transparent. The following article offers a step-by-step guide for developing a web-scale discovery evaluation plan rooted in these five key principles based on best practices synthesized from the literature as well as the author’s own experiences coordinating the evaluation process at Rutgers University. The goal is to offer academic libraries that are considering acquiring a web-scale discovery service a blueprint for planning a structured and comprehensive evaluation process.

  18. Thermo-mechanically induced texture evolution and micro-structural change of aluminum metallization

    DEFF Research Database (Denmark)

    Brincker, Mads; Walter, Thomas; Kristensen, Peter Kjær

    2018-01-01

    During operation of high power electronic chips the topside metallization is subjected to cyclic compressive and tensile stresses leading to unwanted thermo-mechanical fatigue of the metallization layer. The stress is caused by the difference in the thermal expansion coefficients...... are not yet fully understood. In this work, we investigate the microstructural evolution of an Al metallization on high power diode chips subjected to passive thermal cycling between 20 and 100ºC. The texture of the Al film is analyzed ex-situ by a combination of electron backscatter diffraction and X...

  19. Thermo-mechanical design of a CW sweep plate emittance scanner

    International Nuclear Information System (INIS)

    Rathke, J.; Peacock, M.; Sredniawski, J.

    1996-01-01

    A sweep plate emittance scanner for use with high power, continuous wave (CW) beams has been designed, fabricated and commissioned at Northrop Grumman. The design is capable of scanning beams of up to 20 kW beam power with a spot diameter as small as 2 cm. The scanner pod is mounted on a ball screw driven linear bearing table that is driven through the beam by a stepper motor at velocities up to 30 cm/sec. This paper presents the thermo-mechanical analysis of the pod moving through a gaussian beam and the details of the mechanical design of the pod and motion system. Analyses to determine scanner cooling schemes and structural materials are presented. (author)

  20. A step-by-step methodology for enterprise interoperability projects

    Science.gov (United States)

    Chalmeta, Ricardo; Pazos, Verónica

    2015-05-01

    Enterprise interoperability is one of the key factors for enhancing enterprise competitiveness. Achieving enterprise interoperability is an extremely complex process which involves different technological, human and organisational elements. In this paper we present a framework to help enterprise interoperability. The framework has been developed taking into account the three domains of interoperability: Enterprise Modelling, Architecture and Platform and Ontologies. The main novelty of the framework in comparison to existing ones is that it includes a step-by-step methodology that explains how to carry out an enterprise interoperability project taking into account different interoperability views, like business, process, human resources, technology, knowledge and semantics.

  1. Effect of thermo-mechanical treatments on the microstructure and mechanical properties of an ODS ferritic steel

    International Nuclear Information System (INIS)

    Oksiuta, Z.; Mueller, P.; Spaetig, P.; Baluc, N.

    2011-01-01

    The Fe-14Cr-2W-0.3Ti-0.3Y 2 O 3 oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steel was fabricated by mechanical alloying of a pre-alloyed, gas atomised powder with yttria nano-particles, followed by hot isostatic pressing and thermo-mechanical treatments (TMTs). Two kinds of TMT were applied: (i) hot pressing, or (ii) hot rolling, both followed by annealing in vacuum at 850 deg. C. The use of a thermo-mechanical treatment was found to yield strong improvement in the microstructure and mechanical properties of the ODS RAF steel. In particular, hot pressing leads to microstructure refinement, equiaxed grains without texture, and an improvement in Charpy impact properties, especially in terms of the upper shelf energy (about 4.5 J). Hot rolling leads to elongated grains in the rolling direction, with a grain size ratio of 6:1, higher tensile strength and reasonable ductility up to 750 deg. C, and better Charpy impact properties, especially in terms of the ductile-to-brittle transition temperature (about 55 deg. C).

  2. Effect of thermo-mechanical treatments on the microstructure and mechanical properties of an ODS ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Oksiuta, Z., E-mail: oksiuta@pb.edu.pl [Bialystok Technical University, Mechanical Department, Wiejska 45c, 15-351 Bialystok (Poland); Mueller, P.; Spaetig, P.; Baluc, N. [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, 5232 Villigen PSI (Switzerland)

    2011-05-15

    The Fe-14Cr-2W-0.3Ti-0.3Y{sub 2}O{sub 3} oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steel was fabricated by mechanical alloying of a pre-alloyed, gas atomised powder with yttria nano-particles, followed by hot isostatic pressing and thermo-mechanical treatments (TMTs). Two kinds of TMT were applied: (i) hot pressing, or (ii) hot rolling, both followed by annealing in vacuum at 850 deg. C. The use of a thermo-mechanical treatment was found to yield strong improvement in the microstructure and mechanical properties of the ODS RAF steel. In particular, hot pressing leads to microstructure refinement, equiaxed grains without texture, and an improvement in Charpy impact properties, especially in terms of the upper shelf energy (about 4.5 J). Hot rolling leads to elongated grains in the rolling direction, with a grain size ratio of 6:1, higher tensile strength and reasonable ductility up to 750 deg. C, and better Charpy impact properties, especially in terms of the ductile-to-brittle transition temperature (about 55 deg. C).

  3. A numerical study of water percolation through an unsaturated variable aperture fracture under coupled thermomechanical effects

    International Nuclear Information System (INIS)

    Tsang, C.F.; Noorishad, J.; Hale, F.V.

    1991-12-01

    In calculation of ground water travel times associated with performance assessment of a nuclear waste repository, the role of fractures may turn out to be very important. There are two aspects related to fracture flow that have not been fully resolved. The first is the effect of coupled thermomechanical impact on fracture apertures due to the thermal output of the nuclear waste repository. The second is the effect of the variable aperture nature of the fractures. The present paper is an exploratory study of the impact of these two effects on water percolation through unsaturated fractures. The paper is divided into two main sections. the first section describes a calculation of the thermomechanical behavior of the geologic formation around a waste repository. In this exploratory study we assume two major fractures, one vertical and one horizontal through the repository center. Temperatures and thermally induced stress fields are calculated. The second part of the paper considers the unsaturated case and describes a study of water infiltration from the land surface through the vertical fracture to the repository

  4. Thermomechanical properties of the silanized-kenaf/polystyrene composites

    Directory of Open Access Journals (Sweden)

    2009-10-01

    Full Text Available In order to improve the poor interfacial adhesion of the kenaf fiber and polystyrene (PS in their composite material, the surface of the kenaf fiber was modified using a synthesized polymeric coupling agent to promote adhesion with PS matrix. The dynamic thermo-mechanical properties of the composite composed of modified kenaf fiber and PS were also investigated. The polymeric coupling agent treatment of the kenaf fiber increased the fiber-matrix interaction through a condensation reaction between alkoxysilane and hydroxyl groups of kenaf cellulose. DMA (Dynamic Mechanical Thermal Analysis results showed that the modified fiber composites have higher E′ and lower tanδ than those with untreated fiber indicating that a greater interfacial interaction between the matrix resin and the fiber. It was also found that the storage modulus increases in proportion with the Si/C ratio on the fiber surface.

  5. Simulation of the Press Hardening Process and Prediction of the Final Mechanical Material Properties

    Science.gov (United States)

    Hochholdinger, Bernd; Hora, Pavel; Grass, Hannes; Lipp, Arnulf

    2011-08-01

    Press hardening is a well-established production process in the automotive industry today. The actual trend of this process technology points towards the manufacturing of parts with tailored properties. Since the knowledge of the mechanical properties of a structural part after forming and quenching is essential for the evaluation of for example the crash performance, an accurate as possible virtual assessment of the production process is more than ever necessary. In order to achieve this, the definition of reliable input parameters and boundary conditions for the thermo-mechanically coupled simulation of the process steps is required. One of the most important input parameters, especially regarding the final properties of the quenched material, is the contact heat transfer coefficient (IHTC). The CHTC depends on the effective pressure or the gap distance between part and tool. The CHTC at different contact pressures and gap distances is determined through inverse parameter identification. Furthermore a simulation strategy for the subsequent steps of the press hardening process as well as adequate modeling approaches for part and tools are discussed. For the prediction of the yield curves of the material after press hardening a phenomenological model is presented. This model requires the knowledge of the microstructure within the part. By post processing the nodal temperature history with a CCT diagram the quantitative distribution of the phase fractions martensite, bainite, ferrite and pearlite after press hardening is determined. The model itself is based on a Hockett-Sherby approach with the Hockett-Sherby parameters being defined in function of the phase fractions and a characteristic cooling rate.

  6. RODSWELL: a computer code for the thermomechanical analysis of fuel rods under LOCA conditions

    International Nuclear Information System (INIS)

    Casadei, F.; Laval, H.; Donea, J.; Jones, P.M.; Colombo, A.

    1984-01-01

    The present report is the user's manual for the computer code RODSWELL developed at the JRC-Ispra for the thermomechanical analysis of LWR fuel rods under simulated loss-of-coolant accident (LOCA) conditions. The code calculates the variation in space and time of all significant fuel rod variables, including fuel, gap and cladding temperature, fuel and cladding deformation, cladding oxidation and rod internal pressure. The essential characteristics of the code are briefly outlined here. The model is particularly designed to perform a full thermal and mechanical analysis in both the azimuthal and radial directions. Thus, azimuthal temperature gradients arising from pellet eccentricity, flux tilt, arbitrary distribution of heat sources in the fuel and the cladding and azimuthal variation of coolant conditions can be treated. The code combines a transient 2-dimensional heat conduction code and a 1-dimentional mechanical model for the cladding deformation. The fuel rod is divided into a number of axial sections and a detailed thermomechanical analysis is performed within each section in radial and azimuthal directions. In the following sections, instructions are given for the definition of the data files and the semi-variable dimensions. Then follows a complete description of the input data. Finally, the restart option is described

  7. Three-Dimensional Finite Element Modeling of Thermomechanical Problems in Functionally Graded Hydroxyapatite/Titanium Plate

    Directory of Open Access Journals (Sweden)

    S. N. S. Jamaludin

    2014-01-01

    Full Text Available The composition of hydroxyapatite (HA as the ceramic phase and titanium (Ti as the metallic phase in HA/Ti functionally graded materials (FGMs shows an excellent combination of high biocompatibility and high mechanical properties in a structure. Because the gradation of these properties is one of the factors that affects the response of the functionally graded (FG plates, this paper is presented to show the domination of the grading parameter on the displacement and stress distribution of the plates. A three-dimensional (3D thermomechanical model of a 20-node brick quadratic element is used in the simulation of the thermoelastic behaviors of HA/Ti FG plates subjected to constant and functional thermal, mechanical, and thermomechanical loadings. The convergence properties of the present results are examined thoroughly in order to assess the accuracy of the theory applied and to compare them with the established research results. Instead of the grading parameter, this study reveals that the loading field distribution can be another factor that reflects the thermoelastic properties of the HA/Ti FG plates. The FG structure is found to be able to withstand the thermal stresses while preserving the high toughness properties and thus shows its ability to operate at high temperature.

  8. THERMO-MECHANICAL PULPING AS A PRETREATMENT FOR AGRICULTURAL BIOMASS FOR BIOCHEMICAL CONVERSION

    Directory of Open Access Journals (Sweden)

    Ronalds W. Gonzalez

    2011-03-01

    Full Text Available The use of thermo-mechanical pulping (TMP, an existing and well known technology in the pulp and paper industry, is proposed as a potential pretreatment pathway of agriculture biomass for monomeric sugar production in preparation for further fermentation into alcohol species. Three agricultural biomass types, corn stover, wheat straw, and sweet sorghum bagasse, were pretreated in a TMP unit under two temperature conditions, 160 ºC and 170 ºC, and hydrolyzed using cellulase at 5, 10, and 20 FPU/g OD biomass. Wheat straw biomass was further pretreated at different conditions including: i soaking with acetic acid, ii longer steaming residence time (15 and 30 min, and iii refined at lower disk gap (0.0508 and 0.1524 mm. Preliminary results showed that carbohydrate conversion increased from 25% to 40% when the TMP temperature was increased from 160 to 170 ºC. Carbohydrate conversion was relatively similar for the three biomasses under the same pretreatment conditions and enzyme loading. Acetic acid soaking and refining at a reduce disk gap increases carbohydrate conversion. Further studies within this technological field to identify optimum process and TMP conditions for pretreatment are suggested.

  9. Rapid decay of vacancy islands at step edges on Ag(111): step orientation dependence

    International Nuclear Information System (INIS)

    Shen, Mingmin; Thiel, P A; Jenks, Cynthia J; Evans, J W

    2010-01-01

    Previous work has established that vacancy islands or pits fill much more quickly when they are in contact with a step edge, such that the common boundary is a double step. The present work focuses on the effect of the orientation of that step, with two possibilities existing for a face centered cubic (111) surface: A- and B-type steps. We find that the following features can depend on the orientation: (1) the shapes of islands while they shrink; (2) whether the island remains attached to the step edge; and (3) the rate of filling. The first two effects can be explained by the different rates of adatom diffusion along the A- and B-steps that define the pit, enhanced by the different filling rates. The third observation-the difference in the filling rate itself-is explained within the context of the concerted exchange mechanism at the double step. This process is facile at all regular sites along B-steps, but only at kink sites along A-steps, which explains the different rates. We also observe that oxygen can greatly accelerate the decay process, although it has no apparent effect on an isolated vacancy island (i.e. an island that is not in contact with a step).

  10. On the hot cracking susceptibility of a semisolid aluminium 6061 weld: Application of a coupled solidification- thermomechanical model

    International Nuclear Information System (INIS)

    Rajani, H R Zareie; Phillion, A B

    2015-01-01

    A coupled solidification-thermomechanical model is presented that investigates the hot tearing susceptibility of an aluminium 6061 semisolid weld. Two key phenomena are considered: excessive deformation of the semisolid weld, initiating a hot tear, and the ability of the semisolid weld to heal the hot tear by circulation of the molten metal. The model consists of two major modules: weld solidification and thermomechanical analysis. 1) By means of a multi-scale model of solidification, the microstructural evolution of the semisolid weld is simulated in 3D. The semisolid structure, which varies as a function of welding parameters, is composed of solidifying grains and a network of micro liquid channels. The weld solidification module is utilized to obtain the solidification shrinkage. The size of the micro liquid channels is used as an indicator to assess the healing ability of the semisolid weld. 2) Using the finite element method, the mechanical interaction between the weld pool and the base metal is simulated to capture the transient force field deforming the semisolid weld. Thermomechanical stresses and shrinkage stresses are both considered in the analysis; the solidification contractions are extracted from the weld solidification module and applied to the deformation simulation as boundary conditions. Such an analysis enables characterization of the potential for excessive deformation of the weld. The outputs of the model are used to study the effect of welding parameters including welding current and speed, and also welding constraint on the hot cracking susceptibility of an aluminium alloy 6061 semisolid weld. (paper)

  11. Thermo-mechanical interaction effects in foam cored sandwich panels-correlation between High-order models and Finite element analysis results

    DEFF Research Database (Denmark)

    Palleti, Hara Naga Krishna Teja; Santiuste, Carlos; Thomsen, Ole Thybo

    2010-01-01

    Thermo-mechanical interaction effects including thermal material degradation in polymer foam cored sandwich structures is investigated using the commercial Finite Element Analysis (FEA) package ABAQUS/Standard. Sandwich panels with different boundary conditions in the form of simply supported...

  12. Thermomechanical behavior of graphite and coating materials subjected to a high heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Ioki, K.; Yamada, M.; Nishikawa, M.; Uchikawa, T.; Onozuka, M.; Yamao, H.

    1987-07-01

    This study has been performed for the development of limiter and divertor plates. Their thermal and thermomechanical behavior were examined in heat load experiments with an electron beam facility, and were compared with analysis results. Graphite was proven to have a high thermal shock resistance. Its erosion thickness and thermal contact conductance were also studied. Copper alloy with coating and graphite brazed to metal were tested, and their feasibility was demonstrated for use as limiter and divertor plates of an advanced-type concept.

  13. Enhanced pharmaceutical removal from water in a three step bio-ozone-bio process.

    Science.gov (United States)

    de Wilt, Arnoud; van Gijn, Koen; Verhoek, Tom; Vergnes, Amber; Hoek, Mirit; Rijnaarts, Huub; Langenhoff, Alette

    2018-07-01

    Individual treatment processes like biological treatment or ozonation have their limitations for the removal of pharmaceuticals from secondary clarified effluents with high organic matter concentrations (i.e. 17 mg TOC/L). These limitations can be overcome by combining these two processes for a cost-effective pharmaceutical removal. A three-step biological-ozone-biological (BO 3 B) treatment process was therefore designed for the enhanced pharmaceutical removal from wastewater effluent. The first biological step removed 38% of ozone scavenging TOC, thus proportionally reducing the absolute ozone input for the subsequent ozonation. Complementariness between biological and ozone treatment, i.e. targeting different pharmaceuticals, resulted in cost-effective pharmaceutical removal by the overall BO 3 B process. At a low ozone dose of 0.2 g O 3 /g TOC and an HRT of 1.46 h in the biological reactors, the removal of 8 out of 9 pharmaceuticals exceeded 85%, except for metoprolol (60%). Testing various ozone doses and HRTs revealed that pharmaceuticals were ineffectively removed at 0.1 g O3/g TOC and an HRT of 0.3 h. At HRTs of 0.47 and 1.46 h easily and moderately biodegradable pharmaceuticals such as caffeine, gemfibrozil, ibuprofen, naproxen and sulfamethoxazole were over 95% removed by biological treatment. The biorecalcitrant carbamazepine was completely ozonated at a dose of 0.4 g O 3 /g TOC. Ozonation products are likely biodegraded in the last biological reactor as a 17% TOC removal was found. No appreciable acute toxicity towards D. magna, P. subcapitata and V. fischeri was found after exposure to the influents and effluents of the individual BO 3 B reactors. The BO 3 B process is estimated to increase the yearly wastewater treatment tariff per population equivalent in the Netherlands by less than 10%. Overall, the BO 3 B process is a cost-effective treatment process for the removal of pharmaceuticals from secondary clarified effluents. Copyright

  14. Bainitic transformation during the two-step quenching and partitioning process in a medium carbon steel containing silicon

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.Y.; Lu, X.W. [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wu, X.C.; Min, Y.A. [School of Materials Science and Engineering, Shanghai University, Shanghai 200240 (China); Jin, X.J., E-mail: jin@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-09-15

    Research highlights: In this paper, SEM and TEM were used to characterize microstructure of Q and P steels with different partitioning time at 300 deg. C. The interesting phenomena were discovered and discussed: 1.Lower bainite (bainitic ferrite plus {epsilon}-carbide) rather than carbide-free bainite was observed during partitioning process. 2.The mechanical properties of Q and P steels can be tailored and adjusted through balance volume fraction of retained austenite and lower bainite during partitioning process. 3.The final amount of austenite was influenced by the transformation kinetics of lower bainite during partitioning process. According to the analysis, it can be concluded that associated with carbon partitioning from martensite to austenite, lower bainite transformation inevitably occurred. More importantly, lower bainite transformation seriously affected the mechanical properties of Q and P steels and final amount of austenite. - Abstract: A study of 40SiMnNiCr steel subjected to a two-step quenching and partitioning process (Q and P) is presented. The result suggests that strength variation of Q and P steels during the two-step Q and P process was a cumulative effect of increase of retained austenite fraction, decrease of carbon supersaturation of virgin martensite, and particularly much of lower bainite formation. A trade-off between high strength and good ductility of two-step Q and P steels can be tailored and adjusted by controlling lower bainite fraction. The final amount of austenite was influenced by the transformation kinetics of lower bainite during the partitioning process.

  15. Bainitic transformation during the two-step quenching and partitioning process in a medium carbon steel containing silicon

    International Nuclear Information System (INIS)

    Li, H.Y.; Lu, X.W.; Wu, X.C.; Min, Y.A.; Jin, X.J.

    2010-01-01

    Research highlights: In this paper, SEM and TEM were used to characterize microstructure of Q and P steels with different partitioning time at 300 deg. C. The interesting phenomena were discovered and discussed: 1.Lower bainite (bainitic ferrite plus ε-carbide) rather than carbide-free bainite was observed during partitioning process. 2.The mechanical properties of Q and P steels can be tailored and adjusted through balance volume fraction of retained austenite and lower bainite during partitioning process. 3.The final amount of austenite was influenced by the transformation kinetics of lower bainite during partitioning process. According to the analysis, it can be concluded that associated with carbon partitioning from martensite to austenite, lower bainite transformation inevitably occurred. More importantly, lower bainite transformation seriously affected the mechanical properties of Q and P steels and final amount of austenite. - Abstract: A study of 40SiMnNiCr steel subjected to a two-step quenching and partitioning process (Q and P) is presented. The result suggests that strength variation of Q and P steels during the two-step Q and P process was a cumulative effect of increase of retained austenite fraction, decrease of carbon supersaturation of virgin martensite, and particularly much of lower bainite formation. A trade-off between high strength and good ductility of two-step Q and P steels can be tailored and adjusted by controlling lower bainite fraction. The final amount of austenite was influenced by the transformation kinetics of lower bainite during the partitioning process.

  16. A thermo-mechanical benchmark calculation of an hexagonal can in the BTI accident with ABAQUS code

    International Nuclear Information System (INIS)

    Zucchini, A.

    1988-07-01

    The thermo-mechanical behaviour of an hexagonal can in a benchmark problem (simulating the conditions of a BTI accident in a fuel assembly) is examined by means of the ABAQUS code: the effects of the geometric nonlinearity are shown and the results are compared with those of a previous analysis performed with the INCA code. (author)

  17. Tailoring structures through two-step annealing process in nanostructured aluminum produced by accumulative roll-bonding

    DEFF Research Database (Denmark)

    Kamikawa, Naoya; Huang, Xiaoxu; Hansen, Niels

    2008-01-01

    temperature before annealing at high temperature. By this two-step process, the structure is homogenized and the stored energy is reduced significantly during the first annealing step. As an example, high-purity aluminum has been deformed to a total reduction of 98.4% (equivalent strain of 4.......8) by accumulative roll-bonding at room temperature. Isochronal annealing for 0.5 h of the deformed samples shows the occurrence of recrystallization at 200 °C and above. However, when introducing an annealing step for 6 h at 175 °C, no significant recrystallization is observed and relatively homogeneous structures...... are obtained when the samples afterwards are annealed at higher temperatures up to 300 °C. To underpin these observations, the structural evolution has been characterized by transmission electron microscopy, showing that significant annihilation of high-angle boundaries, low-angle dislocation boundaries...

  18. Thermomechanical analysis of porous solid oxide fuel cell by using peridynamics

    Directory of Open Access Journals (Sweden)

    Hanlin Wang

    2017-06-01

    Full Text Available Solid oxide fuel cell (SOFC is widely used in hybrid marine propulsion systems due to its high power output, excellent emission control and wide fuel suitability. However, the operating temperature in SOFC will rise up to 800–1000 ℃ due to redox reaction among hydrogen and oxygen ions. This provides a suitable environment for ions transporting through ceramic materials. Under such operation temperatures, degradation may occur in the electrodes and electrolyte. As a result, unstable voltage, low capacity and cell failure may eventually occur. This study presents thermomechanical analysis of a porous SOFC cell plate which contains electrodes, electrolytes and pores. A microscale specimen in the shape of a plate is considered in order to maintain uniform temperature loading and increase the accuracy of estimation. A new computational technique, peridynamics, is utilized to calculate the deformations and stresses of the cell plate. Moreover, the crack formation and propagation are also obtained by using peridynamics. According to the numerical results, damage evolution depends on the electrolyte/electrode interface strength during the charging process. For weak interface strength case, damage emerges at the electrode/electrolyte interface. On the other hand, for stronger interface cases, damage emerges on pore boundaries especially with sharp corner.

  19. Inelastic thermomechanical analysis of a generic bedded salt repository. Technical report

    International Nuclear Information System (INIS)

    Callahan, G.D.

    1981-02-01

    The thermomechanical response of a generic bedded salt stratigraphy accommodating a spent fuel repository at a depth of 610 m in a relatively thin salt bed is investigated. The thermal density at waste emplacement was assumed to be 14.8 W/m 2 (60 kW/acre). Emphasis is placed on rock mass properties, elastic and thermal anisotropy (within the shale layers), and structural discontinuities defined as preferred planes of weakness. No attempt is made to include long-term effects of geologic actions, chemical processes, groundwater, and pore water. The rock mass is assumed to contain pre-existing joints and fissures. Therefore, the stratigraphy encompassing the repository (excluding the salt beds) was assumed to be incapable of supporting tensile stresses. Thermoelastic/plastic response of the various sedimentary formations is considered for the intact rock mass and several orientations of preferred planes of weakness. The results indicate an intact buffer zone between the upper strata and the repository approximately 450 m thick, which underwent no irreversible deformation. Contained plastic deformation was observed below the repository along preferred planes of weakness dipping at 60 and 120 degrees. The structural response of this generic bedded salt stratigraphy does not appear to be detrimental to the overall waste containment in the repository

  20. Optical nonlinearity due to thermomechanical effect in the planar and homeotropic nematic liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Poursamad, J.B. [Physics & Optic Engineering Group, University of Bonab, Bonab (Iran, Islamic Republic of); Phirouznia, A. [Department of Physics, Azerbaijan ShahidMadani University, 53714-161 Tabriz (Iran, Islamic Republic of); Sahrai, M. [Research Institue for Applied Physics and Astronomy, Univerity of Tabriz, Tabriz (Iran, Islamic Republic of)

    2015-11-01

    Possibility of observing third thermomechanical (TM) effect in uniform nematic liquid crystals (NLC) with proper selection of boundary conditions on the cell walls is theoretically studied. Absorption of a light wave induces the needed temperature gradient for the TM effect. The molecular director reorientation due to third TM effect and the induced phase shift on the probe beam are calculated. The forth TM coefficient can be measured directly by the method proposed in this work.

  1. 3-D thermo-mechanical laboratory modeling of plate-tectonics: modeling scheme, technique and first experiments

    Directory of Open Access Journals (Sweden)

    D. Boutelier

    2011-05-01

    Full Text Available We present an experimental apparatus for 3-D thermo-mechanical analogue modeling of plate tectonic processes such as oceanic and continental subductions, arc-continent or continental collisions. The model lithosphere, made of temperature-sensitive elasto-plastic analogue materials with strain softening, is submitted to a constant temperature gradient causing a strength reduction with depth in each layer. The surface temperature is imposed using infrared emitters, which allows maintaining an unobstructed view of the model surface and the use of a high resolution optical strain monitoring technique (Particle Imaging Velocimetry. Subduction experiments illustrate how the stress conditions on the interplate zone can be estimated using a force sensor attached to the back of the upper plate and adjusted via the density and strength of the subducting lithosphere or the lubrication of the plate boundary. The first experimental results reveal the potential of the experimental set-up to investigate the three-dimensional solid-mechanics interactions of lithospheric plates in multiple natural situations.

  2. Synthesis of highly ordered nanopores on alumina by two-step anodization process

    Energy Technology Data Exchange (ETDEWEB)

    Bwana, Nicholas N. [University of Oxford, Department of Engineering Science (United Kingdom)], E-mail: Nicholas.Bwana@eng.ox.ac.uk

    2008-02-15

    Highly ordered anodic alumina was produced, on RF sputtered aluminium on a conductive glass substrate, by two step anodizing process in 0.4 M sulphuric acid at constant cell potentials of between 5 and 25 V and at a constant current density of 20 mA cm{sup -2}. The temperature was kept constant at 15 deg. C during both anodization processes. The effects of the anodizing potential, current density, and time on the pore diameters were established. Longer anodization periods result in wider irregular pores with reduced porosity for both constant potential and constant current density anodization processes. The current density increases with increasing constant anodizing potential and generally remains constant with time after a sharp rise. Potential drop during constant current density anodization behaves in a similar manner. We confirm that sulphuric acid has a self-ordering potential of 25 V above which burning occurs.

  3. The prediction of mechanical performance of isotactic polypropylene on the basis of processing conditions

    NARCIS (Netherlands)

    Caelers, H.J.M.; Govaert, L.E.; Peters, G.W.M.

    2016-01-01

    A strategy is presented to predict the yield kinetics following from different thermomechanical histories experienced during processing in non-isothermal quiescent conditions. This strategy deals with three main parts, i.e. processing, structure and properties. In the first part the applied cooling

  4. Single-step syngas-to-distillates (S2D) process based on biomass-derived syngas--a techno-economic analysis.

    Science.gov (United States)

    Zhu, Yunhua; Jones, Susanne B; Biddy, Mary J; Dagle, Robert A; Palo, Daniel R

    2012-08-01

    This study compared biomass gasification based syngas-to-distillate (S2D) systems using techno-economic analysis (TEA). Three cases, state of technology (SOT), goal, and conventional, were compared in terms of performance and cost. The SOT case represented the best available experimental results for a process starting with syngas using a single-step dual-catalyst reactor for distillate generation. The conventional case mirrored a conventional two-step S2D process consisting of separate syngas-to-methanol and methanol-to-gasoline (MTG) processes. The goal case assumed the same performance as the conventional, but with a single-step S2D technology. TEA results revealed that the SOT was more expensive than the conventional and goal cases. The SOT case suffers from low one-pass yield and high selectivity to light hydrocarbons, both of which drive up production cost. Sensitivity analysis indicated that light hydrocarbon yield and single pass conversion efficiency were the key factors driving the high cost for the SOT case. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. On capabilities of thermomechanical treatment in increasing durability of short service life elements of mining аnd processing equipment

    Directory of Open Access Journals (Sweden)

    В. И. Болобов

    2016-11-01

    Full Text Available Hadfield steel (110G13L is the basic material for fast wornout items of mining equipment: beaters, hammers, liners, refractory plates of crushers and mills. By way of example, the effect of cold hardening was specifically analyzed on the rate of wear of mining equipment parts for various types of wear by hard (more than 1100 HV and soft rock. A unique ability of that steel to resist shock wear is noted. It is shown that this steel exhibits low resistance to abrasive rock wear. Meanwhile wear by rock of hardness lower than steel (less than 1100 HV, may be substantially increased by pre-hardening of samples (up to 10-fold. In case of wear by high hardness rocks, shock impact that should contribute to hardening of the material, fails  to increase abrasive wear resistance of Hadfield steel, and in that parameter it does not differ from the conventional medium carbon steel 45. Also, the authors of this article describe a technique they developed of high-temperature thermomechanical treatment of specimen of Hadfield steel (free forging at 1150-950ºC and subsequent quenching in water and experiments in their abrasion. The results of tests show that hardness and wear resistance of Hadfield steel to hard abrasive (corundum 25A with aggregate hardness of ~2500 HV increases with plastic deformation at HTMT. For maximum plastic deformation intensity (deformation magnitude of α = 2.25, reached in the experiments by the authors, wear resistance grew by 70% as compared to undeformed steel. The dependence is presented of wear resistance of steel on hardness, HV, achieved in the result of plastic deformation. Since a similar positive effect was obtained earlier by the authors for 35HGSA steel, also used in mining machinery, they conclude that the HTMT technique may be recommended for treating short lived parts of the mining and mineral processing equipment to increase their service life.

  6. Experimental study of the pressure discharge process for the hydraulic control rod drive system stepped cylinder

    International Nuclear Information System (INIS)

    Wang, Jinhua; Bo, Hanliang; Zheng, Wenxiang

    2002-01-01

    The pressure discharge process from the stepped cylinder of the Hydraulic Control Rod Drive System (HCRDS) was studied experimentally in the HCRDS experimental loop for the 200 MW Nuclear Heating Reactor (NHR-200). The results showed that the differential pressure between the outside and the inside of the stepped cylinder increased rapidly to the desired value so that the force induced by the differential pressure which pushes the out tube of stepped cylinder was large enough. Therefore, if the hydraulic control rod were jammed, the pressure could push the hydraulic control rod to overcome the frictional resistance to insert the control rod into the reactor core. The experimental results verified that this design would solve the problem of hydraulic control rod jamming during an accident. (author)

  7. Multiscale Modeling at Nanointerfaces: Polymer Thin Film Materials Discovery via Thermomechanically Consistent Coarse Graining

    Science.gov (United States)

    Hsu, David D.

    Due to high nanointerfacial area to volume ratio, the properties of "nanoconfined" polymer thin films, blends, and composites become highly altered compared to their bulk homopolymer analogues. Understanding the structure-property mechanisms underlying this effect is an active area of research. However, despite extensive work, a fundamental framework for predicting the local and system-averaged thermomechanical properties as a function of configuration and polymer species has yet to be established. Towards bridging this gap, here, we present a novel, systematic coarse-graining (CG) method which is able to capture quantitatively, the thermomechanical properties of real polymer systems in bulk and in nanoconfined geometries. This method, which we call thermomechanically consistent coarse-graining (TCCG), is a two-bead-per-monomer CG hybrid approach through which bonded interactions are optimized to match the atomistic structure via the Iterative Boltzmann Inversion method (IBI), and nonbonded interactions are tuned to macroscopic targets through parametric studies. We validate the TCCG method by systematically developing coarse-grain models for a group of five specialized methacrylate-based polymers including poly(methyl methacrylate) (PMMA). Good correlation with bulk all-atom (AA) simulations and experiments is found for the temperature-dependent glass transition temperature (Tg) Flory-Fox scaling relationships, self-diffusion coefficients of liquid monomers, and modulus of elasticity. We apply this TCCG method also to bulk polystyrene (PS) using a comparable coarse-grain CG bead mapping strategy. The model demonstrates chain stiffness commensurate with experiments, and we utilize a density-correction term to improve the transferability of the elastic modulus over a 500 K range. Additionally, PS and PMMA models capture the unexplained, characteristically dissimilar scaling of Tg with the thickness of free-standing films as seen in experiments. Using vibrational

  8. Computational Abstraction Steps

    DEFF Research Database (Denmark)

    Thomsen, Lone Leth; Thomsen, Bent; Nørmark, Kurt

    2010-01-01

    and class instantiations. Our teaching experience shows that many novice programmers find it difficult to write programs with abstractions that materialise to concrete objects later in the development process. The contribution of this paper is the idea of initiating a programming process by creating...... or capturing concrete values, objects, or actions. As the next step, some of these are lifted to a higher level by computational means. In the object-oriented paradigm the target of such steps is classes. We hypothesise that the proposed approach primarily will be beneficial to novice programmers or during...... the exploratory phase of a program development process. In some specific niches it is also expected that our approach will benefit professional programmers....

  9. A new heat transfer analysis in machining based on two steps of 3D finite element modelling and experimental validation

    Science.gov (United States)

    Haddag, B.; Kagnaya, T.; Nouari, M.; Cutard, T.

    2013-01-01

    Modelling machining operations allows estimating cutting parameters which are difficult to obtain experimentally and in particular, include quantities characterizing the tool-workpiece interface. Temperature is one of these quantities which has an impact on the tool wear, thus its estimation is important. This study deals with a new modelling strategy, based on two steps of calculation, for analysis of the heat transfer into the cutting tool. Unlike the classical methods, considering only the cutting tool with application of an approximate heat flux at the cutting face, estimated from experimental data (e.g. measured cutting force, cutting power), the proposed approach consists of two successive 3D Finite Element calculations and fully independent on the experimental measurements; only the definition of the behaviour of the tool-workpiece couple is necessary. The first one is a 3D thermomechanical modelling of the chip formation process, which allows estimating cutting forces, chip morphology and its flow direction. The second calculation is a 3D thermal modelling of the heat diffusion into the cutting tool, by using an adequate thermal loading (applied uniform or non-uniform heat flux). This loading is estimated using some quantities obtained from the first step calculation, such as contact pressure, sliding velocity distributions and contact area. Comparisons in one hand between experimental data and the first calculation and at the other hand between measured temperatures with embedded thermocouples and the second calculation show a good agreement in terms of cutting forces, chip morphology and cutting temperature.

  10. Microstructures and Properties of 40Cu/Ag(Invar) Composites Fabricated by Powder Metallurgy and Subsequent Thermo-Mechanical Treatment

    Science.gov (United States)

    Zhang, Xin; Huang, Yingqiu; Liu, Xiangyu; Yang, Lei; Shi, Changdong; Wu, Yucheng; Tang, Wenming

    2018-03-01

    Composites of 40Cu/Ag(Invar) were prepared via pressureless sintering and subsequent thermo-mechanical treatment from raw materials of electroless Ag-plated Invar alloy powder and electrolytic Cu powder. Microstructures and properties of the prepared composites were studied to evaluate the effect of the Ag layer on blocking Cu/Invar interfacial diffusion in the composites. The electroless-plated Ag layer was dense, uniform, continuous, and bonded tightly with the Invar alloy substrate. During sintering of the composites, the Ag layer effectively prevented Cu/Invar interfacial diffusion. During cold-rolling, the Ag layer was deformed uniformly with the Invar alloy particles. The composites exhibited bi-continuous network structure and considerably improved properties. After sintering at 775 °C and subsequent thermo-mechanical treatment, the 40Cu/Ag(Invar) composites showed satisfactory comprehensive properties: relative density of 99.0 pct, hardness of HV 253, thermal conductivity of 55.7 W/(m K), and coefficient of thermal expansion of 11.2 × 10-6/K.

  11. Thermomechanical behavior of graphite and coating materials subjected to a high heat flux

    International Nuclear Information System (INIS)

    Ioki, K.; Yamada, M.; Nishikawa, M.; Uchikawa, T.; Onozuka, M.; Yamao, H.

    1987-01-01

    This study has been performed for the development of limiter and divertor plates. Their thermal and thermomechanical behavior were examined in heat load experiments with an electron beam facility, and were compared with analysis results. Graphite was proven to have a high thermal shock resistance. Its erosion thickness and thermal contact conductance were also studied. Copper alloy with coating and graphite brazed to metal were tested, and their feasibility was demonstrated for use as limiter and divertor plates of an advanced-type concept. (orig.)

  12. Description of the shape memory effect of radiation-modified polymers under thermomechanical action

    International Nuclear Information System (INIS)

    Chernous, D.A.; Shil'ko, S.V.; Pleskachevskij, Yu.M.

    2004-01-01

    The 'shape memory' effect of crystallizing polymer materials is simulated. The polymer is considered to be an inhomogeneous medium with a moving boundary (temperature-dependent phase composition). Using a model based on the 'frozen strain' hypothesis, the temperature dependences of stresses under isometric heating and cooling have been obtained. On the basis of the known data on the influence of gamma-irradiation on the thermomechanical characteristics the dependences of thermorelaxation and thermoshrinkage stresses on the absorbed dose for high-density polyethylene have been found. (Authors)

  13. Analysis of the thermo-mechanical behaviour of the DEMO Water-Cooled Lithium Lead breeding blanket module under normal operation steady state conditions

    Energy Technology Data Exchange (ETDEWEB)

    Di Maio, P.A.; Arena, P. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Aubert, J. [CEA Saclay, DEN/DANS/DM2S/SEMT, 91191 Gif sur Yvette Cedex (France); Bongiovì, G. [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Chiovaro, P., E-mail: pierluigi.chiovaro@unipa.it [Dipartimento di Energia, Ingegneria dell’Informazione e Modelli Matematici, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Giammusso, R. [ENEA – C.R. Brasimone, 40032 Camugnano (Italy); Li Puma, A. [CEA Saclay, DEN/DANS/DM2S/SEMT, 91191 Gif sur Yvette Cedex (France); Tincani, A. [ENEA – C.R. Brasimone, 40032 Camugnano (Italy)

    2015-10-15

    Highlights: • A DEMO WCLL blanket module thermo-mechanical behaviour has been investigated. • Two models of the WCLL blanket module have been set-up adopting a code based on FEM. • The water flow domain in the module has been considered. • A set of uncoupled steady state thermo-mechanical analyses has been carried out. • Critical temperature is not overcome. Safety verifications are generally satisfied. - Abstract: Within the framework of DEMO R&D activities, a research cooperation has been launched between ENEA, the University of Palermo and CEA to investigate the thermo-mechanical behaviour of the outboard equatorial module of the DEMO1 Water-Cooled Lithium Lead (WCLL) blanket under normal operation steady state scenario. The research campaign has been carried out following a theoretical–computational approach based on the Finite Element Method (FEM) and adopting a qualified commercial FEM code. In particular, two different 3D FEM models (Model 1 and Model 2), reproducing respectively the central and the lateral poloidal–radial slices of the WCLL blanket module, have been set up. A particular attention has been paid to the modelling of water flow domain, within both the segment box channels and the breeder zone tubes, to simulate realistically the coolant-box thermal coupling. Results obtained are herewith reported and critically discussed.

  14. Technical support for GEIS: radioactive waste isolation in geologic formations. Volume 20. Thermo-mechanical stress analysis and development of thermal loading guidelines

    International Nuclear Information System (INIS)

    1978-04-01

    This volume is one of a 23-volume series which supplements a Contribution to Draft Generic Environmental Impact Statement on Commercial Waste Management: Radioactive Waste Isolation in Geologic Formations, Y/OWI/TM-44. The series provides a more complete technical basis for the preconceptual designs, resource requirements, and environmental source terms associated with isolating commercial LWR wastes in underground repositories in salt, granite, shale and basalt. Wastes are considered from three fuel cycles: uranium and plutonium recycling, no recycling of spent fuel, and uranium-only recycling. The thermo-mechanical analysis of proposed preconceptual repositories in granite, shale and basalt have been undertaken. The analysis, was conducted on three different levels of scale (i) Very Near Field (canister scale), (ii) Near Field (excavation scale) and (iii) Far Field (regional scale) studies. Three numerical methods were used to undertake the thermo-mechanical calculations; namely, the finite element method for thermal stress analysis, the boundary element method for thermal and thermal stress analysis and the semi-analytical method also for thermal and thermal stresses analysis. From the thermo-mechanical studies with simplifying assumptions on rock mass behavior where applicable, recommendations for areal thermal loadings to assure retrievability of the canisters and long term safety of the repository are given

  15. Design of an Annular Disc Subject to Thermomechanical Loading

    Directory of Open Access Journals (Sweden)

    Sergei Alexandrov

    2012-01-01

    Full Text Available Two solutions to design a thin annular disc of variable thickness subject to thermomechanical loading are proposed. It is assumed that the thickness of the disc is everywhere sufficiently small for the stresses to be averaged through the thickness. The state of stress is plane. The initiation of plastic yielding is controlled by Mises yield criterion. The design criterion for one of the solutions proposed requires that the distribution of stresses is uniform over the entire disc. In this case there is a relation between optimal values of the loading parameters at the final stage. The specific shape of the disc corresponds to each pair of such parameters. The other solution is obtained under the additional requirement that the distribution of strains is uniform. This solution exists for the disc of constant thickness at specific values of the loading parameters.

  16. Thermo-mechanical tests of a CFC divertor mock-up

    International Nuclear Information System (INIS)

    Cardella, A.; Akiba, M.; Duwe, R.; Di Pietro, E.; Suzuki, S.; Satoh, K.; Reheis, N.

    1994-01-01

    Thermo-mechanical tests have been performed on a divertor mock-up consisting of a metallic tube armoured with five carbon fibre composite tiles. The tube is inserted the tiles and brazed with TiCuSil braze (monoblock concept). The tube material is TZM, a molybdenum alloy, and the armour material is SEP CARB N112, a high conductivity carbon-carbon composite. Using special surface preparation consisting of laser drilling, small (≅ 500 μm) holes in the composite have been made to increase the surface wetted by the braze and the resistance. The mock-up has been tested at the JAERI 400 kW electron beam test facility JEBIS. The aim of the test was to assess the performance of the mock-up in screening and thermal fatigue tests with particular attention to the behaviour of the armour to heat sink joint. (orig.)

  17. Transport processes investigation: A necessary first step in site scale characterization plans

    International Nuclear Information System (INIS)

    Roepke, C.; Glass, R.J.; Brainard, J.; Mann, M.; Kriel, K.; Holt, R.; Schwing, J.

    1995-01-01

    We propose an approach, which we call the Transport Processes Investigation or TPI, to identify and verify site-scale transport processes and their controls. The TPI aids in the formulation of an accurate conceptual model of flow and transport, an essential first step in the development of a cost effective site characterization strategy. The TPI is demonstrated in the highly complex vadose zone of glacial tills that underlie the Fernald Environmental Remediation Project (FEMP) in Fernald, Ohio. As a result of the TPI, we identify and verify the pertinent flow processes and their controls, such as extensive macropore and fracture flow through layered clays, which must be included in an accurate conceptual model of site-scale contaminant transport. We are able to conclude that the classical modeling and sampling methods employed in some site characterization programs will be insufficient to characterize contaminant concentrations or distributions at contaminated or hazardous waste facilities sited in such media

  18. Thermo-Mechanical Characterisation of In-Plane Properties for CSM E-glass Epoxy Polymer Composite Materials – Part 1

    DEFF Research Database (Denmark)

    Jakobsen, Johnny; Jensen, Martin; Andreasen, Jens H.

    2013-01-01

    The in-plane thermo-mechanical properties and residual stresses of a CSM E-glass/Epoxy material are characterised through the use of DSC and TMA. The measured data is used to generate material models which describe the mechanical behaviour as a function of conversion and temperature. The in-plane...

  19. The Numerical Nuclear Reactor for High-Fidelity Integrated Simulation of Neutronic, Thermal-Hydraulic, and Thermo-Mechanical Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. S.; Ju, H. G.; Jeon, T. H. and others

    2005-03-15

    A comprehensive high fidelity reactor core modeling capability has been developed for detailed analysis of current and advanced reactor designs as part of a US-ROK collaborative I-NERI project. High fidelity was accomplished by integrating highly refined solution modules for the coupled neutronic, thermal-hydraulic, and thermo-mechanical phenomena. Each solution module employs methods and models that are formulated faithfully to the first-principles governing the physics, real geometry, and constituents. Specifically, the critical analysis elements that are incorporated in the coupled code capability are whole-core neutron transport solution, ultra-fine-mesh computational fluid dynamics/heat transfer solution, and finite-element-based thermo-mechanics solution, all obtained with explicit (fuel pin cell level) heterogeneous representations of the components of the core. The vast computational problem resulting from such highly refined modeling is solved on massively parallel computers, and serves as the 'numerical nuclear reactor'. Relaxation of modeling parameters were also pursued to make problems run on clusters of workstations and PCs for smaller scale applications as well.

  20. The Numerical Nuclear Reactor for High-Fidelity Integrated Simulation of Neutronic, Thermal-Hydraulic, and Thermo-Mechanical Phenomena

    International Nuclear Information System (INIS)

    Kim, K. S.; Ju, H. G.; Jeon, T. H. and others

    2005-03-01

    A comprehensive high fidelity reactor core modeling capability has been developed for detailed analysis of current and advanced reactor designs as part of a US-ROK collaborative I-NERI project. High fidelity was accomplished by integrating highly refined solution modules for the coupled neutronic, thermal-hydraulic, and thermo-mechanical phenomena. Each solution module employs methods and models that are formulated faithfully to the first-principles governing the physics, real geometry, and constituents. Specifically, the critical analysis elements that are incorporated in the coupled code capability are whole-core neutron transport solution, ultra-fine-mesh computational fluid dynamics/heat transfer solution, and finite-element-based thermo-mechanics solution, all obtained with explicit (fuel pin cell level) heterogeneous representations of the components of the core. The vast computational problem resulting from such highly refined modeling is solved on massively parallel computers, and serves as the 'numerical nuclear reactor'. Relaxation of modeling parameters were also pursued to make problems run on clusters of workstations and PCs for smaller scale applications as well

  1. On the Effects of Thermal History on the Development and Relaxation of Thermo-Mechanical Stress in Cryopreservation.

    Science.gov (United States)

    Eisenberg, David P; Steif, Paul S; Rabin, Yoed

    2014-01-01

    This study investigates the effects of the thermal protocol on the development and relaxation of thermo-mechanical stress in cryopreservation by means of glass formation, also known as vitrification. The cryopreserved medium is modeled as a homogeneous viscoelastic domain, constrained within either a stiff cylindrical container or a highly compliant bag. Annealing effects during the cooling phase of the cryopreservation protocol are analyzed. Results demonstrate that an intermediate temperature-hold period can significantly reduce the maximum tensile stress, thereby decreasing the potential for structural damage. It is also demonstrated that annealing at temperatures close to glass transition significantly weakens the dependency of thermo-mechanical stress on the cooling rate. Furthermore, a slower initial rewarming rate after cryogenic storage may drastically reduce the maximum tensile stress in the material, which supports previous experimental observations on the likelihood of fracture at this stage. This study discusses the dependency of the various stress components on the storage temperature. Finally, it is demonstrated that the stiffness of the container wall can affect the location of maximum stress, with implications on the development of cryopreservation protocols.

  2. Thermo-mechanical fatigue behavior of the intermetallic gamma-TiAl alloy TNB-V5 with different microstructures

    International Nuclear Information System (INIS)

    Roth, M; Biermann, H

    2010-01-01

    The cyclic deformation and fatigue behavior of the γ-TiAl alloy TNB-V5 is studied under thermo-mechanical load for the three technically important microstructures Fully-Lamellar (FL), Near-Gamma (NG) and Duplex (DP), respectively. Thus, thermo-mechanical fatigue (TMF) tests were carried out with different temperature-strain cycles, different temperature ranges from 400 0 C to 800 0 C and with two different strain ranges. Cyclic deformation curves, stress-strain hysteresis loops and fatigue lives are presented. The type of microstructure shows a surprisingly small influence on the cyclic deformation and fatigue behavior under TMF conditions. For a general life prediction the damage parameter of Smith, Watson and Topper P SWT is well suitable, if the testing and the application temperature ranges, respectively, include temperatures above the ductile-brittle transition temperature (approx. 750 0 C). If the maximum temperature is below that temperature, the brittle materials' behavior yields a high scatter of fatigue lives and a low slope of the fatigue life curve and therefore the damage parameter P SWT cannot be applied for the live prediction.

  3. Developing novel one-step processes for obtaining food-grade O/W emulsions from pressurized fluid extracts: processes description, state of the art and perspectives

    Directory of Open Access Journals (Sweden)

    Diego Tresinari SANTOS

    2015-01-01

    Full Text Available AbstractIn this work, a novel on-line process for production of food-grade emulsions containing oily extracts, i.e. oil-in-water (O/W emulsions, in only one step is presented. This process has been called ESFE, Emulsions from Supercritical Fluid Extraction. With this process, emulsions containing supercritical fluid extracts can be obtained directly from plant materials. The aim in the conception of this process is to propose a new rapid way to obtain emulsions from supercritical fluid extracts. Nowadays the conventional emulsion formulation method is a two-step procedure, i.e. first supercritical fluid extraction for obtaining an extract; secondly emulsion formulation using another device. Other variation of the process was tested and successfully validated originating a new acronymed process: EPFE (Emulsions from Pressurized Fluid Extractions. Both processes exploit the supercritical CO2-essential oils miscibility, in addition, EPFE process exploits the emulsification properties of saponin-rich pressurized aqueous plant extracts. The feasibility of this latter process was demonstrated using Pfaffia glomerata roots as source of saponin-rich extract, water as extracting solvent and clove essential oil, directly extracted using supercritical CO2, as a model dispersed phase. In addition, examples of pressurized fluid-based coupled processes applied for adding value to food bioactive compounds developed in the past five years are reviewed.

  4. Thermo-mechanical analysis of FG nanobeam with attached tip mass: an exact solution

    Science.gov (United States)

    Ghadiri, Majid; Jafari, Ali

    2016-12-01

    Present disquisition proposes an analytical solution method for exploring the vibration characteristics of a cantilever functionally graded nanobeam with a concentrated mass exposed to thermal loading for the first time. Thermo-mechanical properties of FGM nanobeam are supposed to change through the thickness direction of beam based on the rule of power-law (P-FGM). The small-scale effect is taken into consideration based on nonlocal elasticity theory of Eringen. Linear temperature rise (LTR) through thickness direction is studied. Existence of centralized mass in the free end of nanobeam influences the mechanical and physical properties. Timoshenko beam theory is employed to derive the nonlocal governing equations and boundary conditions of FGM beam attached with a tip mass under temperature field via Hamilton's principle. An exact solution procedure is exploited to achieve the non-dimensional frequency of FG nanobeam exposed to temperature field with a tip mass. A parametric study is led to assess the efficacy of temperature changes, tip mass, small scale, beam thickness, power-law exponent, slenderness and thermal loading on the natural frequencies of FG cantilever nanobeam with a point mass at the free end. It is concluded that these parameters play remarkable roles on the dynamic behavior of FG nanobeam subjected to LTR with a tip mass. The results for simpler states are confirmed with known data in the literature. Presented numerical results can serve as benchmarks for future thermo-mechanical analyses of FG nanobeam with tip mass.

  5. Processing and production of molybdenum and tungsten alloys

    International Nuclear Information System (INIS)

    Hagel, W.C.; Shields, J.A. Jr.; Tuominen, S.M.

    1984-01-01

    The technological means to produce and process Mo and W alloys are summarized because for many Mo and W alloy systems the mechanical properties can be optimized only by thermomechanical processing requiring production and processing capabilities that are not widely available. First, the producers of commercial Mo and W alloys are presented along with currently available product forms. Second, currently disclosed standard capabilities of producers and processors in the United States are presented. 56 references, 13 figures, 9 tables

  6. How to define 'best practice' for use in Knowledge Translation research: a practical, stepped and interactive process.

    Science.gov (United States)

    Bosch, Marije; Tavender, Emma; Bragge, Peter; Gruen, Russell; Green, Sally

    2013-10-01

    Defining 'best practice' is one of the first and crucial steps in any Knowledge Translation (KT) research project. Without a sound understanding of what exactly should happen in practice, it is impossible to measure the extent of existing gaps between 'desired' and 'actual' care, set implementation goals, and monitor performance. The aim of this paper is to present a practical, stepped and interactive process to develop best practice recommendations that are actionable, locally applicable and in line with the best available research-based evidence, with a view to adapt these into process measures (quality indicators) for KT research purposes. Our process encompasses the following steps: (1) identify current, high-quality clinical practice guidelines (CPGs) and extract recommendations; (2) select strong recommendations in key clinical management areas; (3) update evidence and create evidence overviews; (4) discuss evidence and produce agreed 'evidence statements'; (5) discuss the relevance of the evidence with local stakeholders; and (6) develop locally applicable actionable best practice recommendations, suitable for use as the basis of quality indicators. Actionable definitions of local best practice are a prerequisite for doing KT research. As substantial resources go into rigorously synthesizing evidence and developing CPGs, it is important to make best use of such available resources. We developed a process for efficiently developing locally applicable actionable best practice recommendations from existing high-quality CPGs that are in line with current research evidence. © 2012 John Wiley & Sons Ltd.

  7. Effects of V{sub 2}O{sub 5} addition on NiZn ferrite synthesized using two-step sintering process

    Energy Technology Data Exchange (ETDEWEB)

    Hu Jun [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Shi Gang; Ni Zheming; Zheng Li [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China); Chen Aimin, E-mail: hjzjut@zjut.edu.cn [College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032 (China)

    2012-06-15

    The combined influence of a two-step sintering (TSS) process and addition of V{sub 2}O{sub 5} on the microstructure and magnetic properties of NiZn ferrite was investigated. As comparison, samples prepared by the conventional single-step sintering (SSS) procedure were also studied. It was found that with 0.3 wt% V{sub 2}O{sub 5} additive, the sample sintered by the two-step sintering process at a high temperature of 1250 Degree-Sign C for 30 min and a lower temperature of 1180 Degree-Sign C for 3 h exhibited more homogeneous microstructure and higher permeability with a high Q-factor. The results showed that the TSS method with suitable additive brought positive improvement of the microstructure and magnetic properties of NiZn ferrite.

  8. Thermomechanical Stresses Analysis of a Single Event Burnout Process

    Science.gov (United States)

    Tais, Carlos E.; Romero, Eduardo; Demarco, Gustavo L.

    2009-06-01

    This work analyzes the thermal and mechanical effects arising in a power Diffusion Metal Oxide Semiconductor (DMOS) during a Single Event Burnout (SEB) process. For studying these effects we propose a more detailed simulation structure than the previously used by other authors, solving the mathematical models by means of the Finite Element Method. We use a cylindrical heat generation region, with 5 W, 10 W, 50 W and 100 W for emulating the thermal phenomena occurring during SEB processes, avoiding the complexity of the mathematical treatment of the ion-semiconductor interaction.

  9. A meshless approach to thermomechanics of DC casting of aluminium billets

    International Nuclear Information System (INIS)

    Mavrič, B; Šarler, B

    2016-01-01

    The ability to model thermomechanics in DC casting is important due to the technological challenges caused by physical phenomena such as different ingot distortions, cracking, hot tearing and residual stress. Many thermomechanical models already exist and usually take into account three contributions: elastic, thermal expansion, and viscoplastic to model the mushy zone. These models are, in a vast majority, solved by the finite element method. In the present work the elastic model that accounts for linear thermal expansion is considered. The method used for solving the model is of a novel meshless type and extends our previous meshless attempts in solving fluid mechanics problems. The solution to the problem is constructed using collocation on the overlapping subdomains, which are composed of computational nodes. Multiquadric radial basis functions, augmented by monomials, are used for the displacement interpolation. The interpolation is constructed in such a manner that it readily satisfies the boundary conditions. The discretization results in construction of a global square sparse matrix representing the system of linear equations for the displacement field. The developed method has many advantages. The system of equations can be easily constructed and efficiently solved. There is no need to perform expensive meshing of the domain and the formulation of the method is similar in two and three dimensions. Since no meshing is required, the nodes can easily be added or removed, which allows for efficient adaption of the node arrangement density. The order of convergence, estimated through an analytically solvable test, can be adjusted through the number of interpolation nodes in the subdomain, with 6 nodes being enough for the second order convergence. Simulations of axisymmetric mechanical problems, associated with low frequency electromagnetic DC casting are presented. (paper)

  10. Effect of thermo-mechanical treatments on creep and fatigue properties of 9% Cr martensitic steels

    International Nuclear Information System (INIS)

    Hollner, S.; Fournier, B.; Le Pendu, J.; Caes, C.; Tournie, I.; Pineau, A.

    2011-01-01

    In the framework of the development of Generation IV nuclear reactors and fusion nuclear reactors, materials with high mechanical properties up to 550 C are required. In service the materials will be subjected to high-temperature creep and cyclic loadings. 9-12%Cr martensitic steels are candidate materials for these applications; however, they show a pronounced cyclic softening effect under cyclic loadings. This softening effect is linked to the coarsening of the martensitic microstructure. In order to refine its microstructure and its precipitation state, the commercial P91 steel has been submitted to a thermo-mechanical treatment including warm-rolling at 600 C and a tempering stage at 700 C. Microstructural observations confirm that this thermo-mechanical treatment led to a finer martensite with smaller MX-type precipitates. This evolution has an effect on the high-temperature mechanical properties: the optimized P91 steel is 100 Hv harder than the as-received P91, and its yield strength is 430 MPa higher at 20 C and 220 MPa higher at 550 C. Its lifetime under creep (at 650 C under 120 MPa) is at least 14 times longer; and the fatigue test at 650 C under 0.7% strain shows a slightly slower cyclic softening effect for the optimized P91. (authors)

  11. Evolution of mechanical behavior of 6XXX aluminium alloy due to the precipitation state during a thermo-mechanical process

    International Nuclear Information System (INIS)

    Bardel, Didier; Perez, Michel; Nelias, Daniel; Chaise, Thibaut; Garnier, Jerome; Bourlier, Florent

    2014-01-01

    The aim of this research is to link the microstructural state and the mechanical properties of an age hardening alloy during a fast heat treatment such as encountered during welding. A coupled model between precipitation state and mechanical properties is used to predict the yield strength and hardening behavior that can be observed experimentally. The method permits the identification of the kinematic and isotropic contributions in the hardening model. The methodology is applied to a 6061-T6 aluminium alloy which is used in the Jules Horowitz reactor vessel. The general idea of this methodology is to couple an efficient microstructural model to a mechanical one based on the dislocation theory and ad'hoc experiments. The theoretical background is based on the work of Kampmann and Wagner, known as the KWN model, to account for nucleation, growth/dissolution and coarsening of precipitates. This analysis requires transient thermo-mechanical experimental data. The efficiency of these models and their coupling are shown for a series 6XXX aluminium alloy which contains β'' and β' precipitates. Ultimately these models are coupled to a FEA model and allows to predict the distribution of precipitates within each element of the mesh, and subsequently its mechanical behavior. (authors)

  12. Conversation on data mining strategies in LC-MS untargeted metabolomics: pre-processing and pre-treatment steps

    CSIR Research Space (South Africa)

    Tugizimana, F

    2016-11-01

    Full Text Available -MS)-based untargeted metabolomic dataset, this study explored the influence of collection parameters in the data pre-processing step, scaling and data transformation on the statistical models generated, and feature selection, thereafter. Data obtained in positive mode...

  13. Thermomechanical fatigue behavior of SiC/Ti-24Al-11Nb in air and argon environments

    Science.gov (United States)

    Bartolotta, Paul A.; Verrilli, Michael J.

    1992-01-01

    A series of tension-tension, load-controlled thermomechanical fatigue (TMF) tests were conducted on a titanium aluminide composite in both laboratory air and a flowing argon environment. Results from these tests show that the environment plays an increasingly important role as applied stress levels are decreased. Differences in damage mechanisms between the two environments were observed which corresponds to observed variations in TMF lives.

  14. Stability characteristics of compressible boundary layers over thermo-mechanically compliant walls

    Science.gov (United States)

    Dettenrieder, Fabian; Bodony, Daniel

    2017-11-01

    Transition prediction at hypersonic flight conditions continues to be a challenge and results in conservative safety factors that increase vehicle weight. The weight and thus cost reduction of the outer skin panels promises significant impact; however, fluid-structure interaction due to unsteady perturbations in the laminar boundary layer regime has not been systematically studied at conditions relevant for reusable, hypersonic flight. In this talk, we develop and apply convective and global stability analyses for compressible boundary layers over thermo-mechanically compliant panels. This compliance is shown to change the convective stability of the boundary layer modes, with both stabilization and destabilization observed. Finite panel lengths are shown to affect the global stability properties of the boundary layer.

  15. Development of quartz particulate reinforced AA6063 aluminum matrix composites via friction stir processing

    Directory of Open Access Journals (Sweden)

    S. Joyson Abraham

    2016-12-01

    Full Text Available Friction stir processing (FSP has been accepted as a potential method to produce aluminum matrix composites (AMCs without the drawbacks of liquid metallurgy methods. The present work focuses on the development of AMCs reinforced with quartz (SiO2 particles using FSP. Grooves with various dimensions were machined on AA6063 plates and compacted with quartz particles. A single pass FSP was carried out using a combination of optimized process parameters. The volume fraction of quartz particles in the AMCs was varied from 0 to 18 vol.% in steps of 6 vol.%. The developed AA6063/Quartz AMCs were characterized using optical, scanning and transmission electron microscopy. The quartz particles were distributed uniformly in the aluminum matrix irrespective of the location within the stir zone. The grains of the AA6063 were extensively refined by the combination of thermomechanical effect of FSP and the pinning effect of quartz particles. The dispersion of the quartz particles improved the microhardness and wear resistance of the AMCs. The role of quartz particles on the worn surface and wear debris is reported.

  16. Test program element II blanket and shield thermal-hydraulic and thermomechanical testing, experimental facility survey

    Energy Technology Data Exchange (ETDEWEB)

    Ware, A.G.; Longhurst, G.R.

    1981-12-01

    This report presents results of a survey conducted by EG and G Idaho to determine facilities available to conduct thermal-hydraulic and thermomechanical testing for the Department of Energy Office of Fusion Energy First Wall/Blanket/Shield Engineering Test Program. In response to EG and G queries, twelve organizations (in addition to EG and G and General Atomic) expressed interest in providing experimental facilities. A variety of methods of supplying heat is available.

  17. Test program element II blanket and shield thermal-hydraulic and thermomechanical testing, experimental facility survey

    International Nuclear Information System (INIS)

    Ware, A.G.; Longhurst, G.R.

    1981-12-01

    This report presents results of a survey conducted by EG and G Idaho to determine facilities available to conduct thermal-hydraulic and thermomechanical testing for the Department of Energy Office of Fusion Energy First Wall/Blanket/Shield Engineering Test Program. In response to EG and G queries, twelve organizations (in addition to EG and G and General Atomic) expressed interest in providing experimental facilities. A variety of methods of supplying heat is available

  18. Roles of multi-step transfer in fusion process induced by heavy-ion reactions

    International Nuclear Information System (INIS)

    Imanishi, B.; Oertzen, W. von.

    1993-06-01

    In nucleus-nucleus collisions of the systems, 12 C+ 13 C and 13 C+ 16 O- 12 C+ 17 O, the effects of the multi-step transfers and inelastic excitations on the fusion cross sections are investigated in the framework of the coupled-reaction-channel (CRC) method. Strong CRC effects of the multi-step processes are observed. Namely, the valence neutron in 13 C or 17 O plays an important role in the enhancement of the fusion. The potential barrier is effectively lowered with the formation of the covalent molecule of the configuration, 12 C+n+ 12 C or 12 C+n+ 16 O. In the analyses of the system 12 C+ 13 C, however, it is still required to introduce core-core optical potential of lower barrier height in the state of the positive total parity. This could be due to the neck formation with the nucleons contained in two core nuclei. (author)

  19. Probabilistic Simulation of Combined Thermo-Mechanical Cyclic Fatigue in Composites

    Science.gov (United States)

    Chamis, Christos C.

    2011-01-01

    A methodology to compute probabilistically-combined thermo-mechanical fatigue life of polymer matrix laminated composites has been developed and is demonstrated. Matrix degradation effects caused by long-term environmental exposure and mechanical/thermal cyclic loads are accounted for in the simulation process. A unified time-temperature-stress-dependent multifactor-interaction relationship developed at NASA Glenn Research Center has been used to model the degradation/aging of material properties due to cyclic loads. The fast probability-integration method is used to compute probabilistic distribution of response. Sensitivities of fatigue life reliability to uncertainties in the primitive random variables (e.g., constituent properties, fiber volume ratio, void volume ratio, ply thickness, etc.) computed and their significance in the reliability-based design for maximum life is discussed. The effect of variation in the thermal cyclic loads on the fatigue reliability for a (0/+/-45/90)s graphite/epoxy laminate with a ply thickness of 0.127 mm, with respect to impending failure modes has been studied. The results show that, at low mechanical-cyclic loads and low thermal-cyclic amplitudes, fatigue life for 0.999 reliability is most sensitive to matrix compressive strength, matrix modulus, thermal expansion coefficient, and ply thickness. Whereas at high mechanical-cyclic loads and high thermal-cyclic amplitudes, fatigue life at 0.999 reliability is more sensitive to the shear strength of matrix, longitudinal fiber modulus, matrix modulus, and ply thickness.

  20. Inline temperature compensation for dimensional metrology of polymer parts in a production environment based on 3D thermomechanical analysis

    DEFF Research Database (Denmark)

    Sonne, M. R.; Gonzalez, D.; Costa, G. Dalla

    2018-01-01

    Abstract In the present work a new method for thermal compensation in dimensional metrology of polymer parts in a production environment based on 3D thermomechanical simulations is developed. A fixture for measuring the length dimension of a classical polymer part is placed in a production enviro...