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Sample records for abaqus thermomechanics code

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

    R. L. Williamson; D. A. Knoll

    2009-09-01

    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.

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

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

    2009-06-15

    Important aspects of fuel rod behavior, for example pellet-clad interaction (PCI), fuel fracture, and non-axisymmetric cooling and oxide formation, are inherently 3-D. Current fuel rod simulation codes typically approximate such behavior using a quasi 2D (or 1.5D) approach and, often, separate codes must be used for steady and transient (or accident) conditions. Notable exceptions are the EPRI propriety code FALCON which is 2D and can be applied to steady or transient operation, and TOUTATIS which is 3D. Recent studies have indicated the need for multidimensional fuel rod simulation capability, particularly for accurate predictions of PCI. The Idaho National Laboratory (INL) is currently developing next-generation capability to model nuclear fuel performance. The goal is to develop a 2D/3D computer code (BISON) which solves the fully coupled thermomechanics equations, includes multi-physics constitutive behavior for both fuel and cladding materials, and is designed for efficient use on highly parallel computers. To provide guidance and a proto-typing environment for this effort, plus provide the INL with near-term fuel modeling capability, the commercially available ABAQUS thermomechanics software has been enhanced to include the fuel behavior phenomena necessary to afford a practical fuel performance simulation capability. This paper details the enhancements which have been implemented in ABAQUS to date, and provides results of a multi-pellet fuel problem which demonstrates the new capability. ABAQUS employs modern finite element methods to solve the nonlinear thermomechanics equations in 1, 2, or 3-D, using linear or quadratic elements. The temperature and displacement fields are solved in a fully-coupled fashion, using sophisticated iteration and time integration error control. The code includes robust contact algorithms, essential for computing multidimensional pellet-pellet or pellet-clad interaction. Extensive constitutive models are available, including

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

    Important aspects of fuel rod behavior, for example pellet-clad interaction (PCI), fuel fracture, and non-axisymmetric cooling and oxide formation, are inherently 3-D. Current fuel rod simulation codes typically approximate such behavior using a quasi 2D (or 1.5D) approach and, often, separate codes must be used for steady and transient (or accident) conditions. Notable exceptions are the EPRI propriety code FALCON which is 2D and can be applied to steady or transient operation, and TOUTATIS which is 3D. Recent studies have indicated the need for multidimensional fuel rod simulation capability, particularly for accurate predictions of PCI. The Idaho National Laboratory (INL) is currently developing next-generation capability to model nuclear fuel performance. The goal is to develop a 2D/3D computer code (BISON) which solves the fully coupled thermomechanics equations, includes multi-physics constitutive behavior for both fuel and cladding materials, and is designed for efficient use on highly parallel computers. To provide guidance and a proto-typing environment for this effort, plus provide the INL with near-term fuel modeling capability, the commercially available ABAQUS thermomechanics software has been enhanced to include the fuel behavior phenomena necessary to afford a practical fuel performance simulation capability. This paper details the enhancements which have been implemented in ABAQUS to date, and provides results of a multi-pellet fuel problem which demonstrates the new capability. ABAQUS employs modern finite element methods to solve the nonlinear thermomechanics equations in 1, 2, or 3-D, using linear or quadratic elements. The temperature and displacement fields are solved in a fully-coupled fashion, using sophisticated iteration and time integration error control. The code includes robust contact algorithms, essential for computing multidimensional pellet-pellet or pellet-clad interaction. Extensive constitutive models are available, including

  4. Description of modelling to be implemented in the fuel rod thermomechanics code Cyrano3

    CYRANO3 is the new EDF thermomechanical code developed to evaluate the overall fuel rod behavior under irradiation. In that context, this paper presents the phenomena to be simulated and the correlations adopted for modelling purposes. The empirical models presented are taken from the CYRANO2 code and a compilation of the relevant literature. The present revision corrects and supplements version B on the basis of its use during the software coding phase from January 1991 to May 1993. (authors). figs., tabs., 120 refs

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

    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. RODSWELL: a computer code for the thermomechanical analysis of fuel rods under LOCA conditions

    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. Implementation of constitutive equations for creep damage mechanics into the ABAQUS finite element code - some practical cases in high temperature component design and life assessment

    Constitutive equations for creep damage mechanics are implemented into the finite element program ABAQUS using a user supplied subroutine, UMAT. A modified Kachanov-Rabotnov constitutive equation which accounts for inhomogeneity in creep damage is used. With a user defined material a number of bench mark tests are analyzed for verification. In the cases where analytical solutions exist, the numerical results agree very well. In other cases, the creep damage evolution response appear to be realistic in comparison with laboratory creep tests. The appropriateness of using the creep damage mechanics concept in design and life assessment of high temperature components is demonstrated. 18 refs

  8. Development of thermal analysis method for the near field of HLW repository using ABAQUS

    Kuh, Jung Eui; Kang, Chul Hyung; Park, Jeong Hwa [Korea Atomic Energy Research Institute, Taejon (Korea)

    1998-10-01

    An appropriate tool is needed to evaluate the thermo-mechanical stability of high level radioactive waste (HLW) repository. In this report a thermal analysis methodology for the near field of HLW repository is developed to use ABAQUS which is one of the multi purpose FEM code and has been used for many engineering area. The main contents of this methodology development are the structural and material modelling to simulate a repository, setup of side conditions, e.g., boundary and load conditions, and initial conditions, and the procedure to selection proper material parameters. In addition to these, the interface programs for effective production of input data and effective change of model size for sensitivity analysis for disposal concept development are developed. The results of this work will be apply to evaluate the thermal stability and to use as main input data for mechanical analysis of HLW repository. (author). 20 refs., 15 figs., 5 tabs.

  9. SATURN-FS 1: A computer code for thermo-mechanical fuel rod analysis

    The SATURN-FS code was written as a general revision of the SATURN-2 code. SATURN-FS is capable to perform a complete thermomechanical analysis of a fuel pin, with all thermal, mechanical and irradiation-based effects. Analysis is possible for LWR and for LMFBR fuel pins. The thermal analysis consists of calculations of the temperature profile in fuel, gap and in the cladding. Pore migration, stoichiometry change of oxide fuel, gas release and diffusion effects are taken into account. The mechanical modeling allows the non steady-state analysis of elastic and nonelastic fuel pin behaviour, such as creep, strain hardening, recovery and stress relaxation. Fuel cracking and healing is taken into account as well as contact and friction between fuel and cladding. The modeling of the irradiation effects comprises swelling and fission gas production, Pu-migration and irradiation induced creep. The code structure, the models and the requirements for running the code are described in the report. Recommendations for the application are given. Program runs for verification and typical examples of application are given in the last part of this report. (orig.)

  10. Coupled Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

    Johnson, Arthur R.; Chen, Tzi-Kang

    2000-01-01

    A procedure that models coupled thermo-mechanical deformations of viscoelastic rubber cylinders by employing the ABAQUS finite element code is described. Computational simulations of hysteretic heating are presented for several tall and short rubber cylinders both with and without a steel disk at their centers. The cylinders are compressed axially and are then cyclically loaded about the compressed state. The non-uniform hysteretic heating of the rubber cylinders containing a steel disk is presented. The analyses performed suggest that the coupling procedure should be considered for further development as a design tool for rubber degradation studies.

  11. MCTP, a code for the thermo-mechanical analysis of a fuel rod of BWR type reactors (Neutron part)

    In the National Institute of Nuclear Research of Mexico a code for the thermo-mechanical analysis of the fuel rods of the BWR type reactors of the Nucleo electric Central of Laguna Verde is developed. The code solves the diffusion equation in cylindrical coordinates with several energy groups. The code, likewise, calculates the temperature distribution and power distribution in those fuel rods. The code is denominated Multi groups With Temperatures and Power (MCTP). In the code, the energy with which the fission neutrons are emitted it is divided in six groups. They are also considered the produced perturbations by the changes in the temperatures of the materials that constitute the fuel rods, the content of fission products, the uranium consumption and in its case the gadolinium, as well as the plutonium production. In this work there are present preliminary results obtained with the code, using data of operation of the Nucleo electric Central of Laguna Verde. (Author)

  12. Validation of fast reactor thermomechanical and thermohydraulic codes. Final report of a co-ordinated research project. 1996-1999

    This report is a summary of the work performed under a co-ordinated research project (CRP) entitled Harmonization and Validation of Fast Reactor Thermomechanical and Thermo-Hydraulic Codes and Relations using Experimental Data. The project was organized by the IAEA on the recommendation of the IAEA's Technical Working Group on Fast Reactors (TWGFR) and carried out from 1996 to 1999. In certain conditions, temperature fluctuations in the coolant close to a structure caused by thermal striping can lead to thermomechanical damage to structures. Institutes from a number of Member States have an interest in improving engineering tools and prediction techniques concerning the characterization of the thermal striping effects, in which numerical models have a major role. Therefore, the IAEA through its advanced reactor technology development programme supports the activities of Member States in this area. Design analyses applied to thermal striping phenomena need to be firmly established, and the CRP provided a valuable tool in assessing their reliability. Eleven institutes from France, India, Italy, Japan, the Republic of Korea, the Russian Federation and the United Kingdom co-operated in this CRP. This report documents the CRP activities, provides the main results and recommendations and includes the work carried out by the research groups at the participating institutes within the CRP on harmonization and validation of fast reactor thermomechanical and thermohydraulic codes and relations

  13. A new code for predicting the thermo-mechanical and irradiation behavior of metallic fuels in sodium fast reactors

    Karahan, Aydin, E-mail: karahan@mit.ed [Center for Advanced Nuclear Energy Systems, Nuclear Science and Engineering Department, Massachusetts Institute of Technology (United States); Buongiorno, Jacopo [Center for Advanced Nuclear Energy Systems, Nuclear Science and Engineering Department, Massachusetts Institute of Technology (United States)

    2010-01-31

    An engineering code to predict the irradiation behavior of U-Zr and U-Pu-Zr metallic alloy fuel pins and UO{sub 2}-PuO{sub 2} mixed oxide fuel pins in sodium-cooled fast reactors was developed. The code was named Fuel Engineering and Structural analysis Tool (FEAST). FEAST has several modules working in coupled form with an explicit numerical algorithm. These modules describe fission gas release and fuel swelling, fuel chemistry and restructuring, temperature distribution, fuel-clad chemical interaction, and fuel and clad mechanical analysis including transient creep-fracture for the clad. Given the fuel pin geometry, composition and irradiation history, FEAST can analyze fuel and clad thermo-mechanical behavior at both steady-state and design-basis (non-disruptive) transient scenarios. FEAST was written in FORTRAN-90 and has a simple input file similar to that of the LWR fuel code FRAPCON. The metal-fuel version is called FEAST-METAL, and is described in this paper. The oxide-fuel version, FEAST-OXIDE is described in a companion paper. With respect to the old Argonne National Laboratory code LIFE-METAL and other same-generation codes, FEAST-METAL emphasizes more mechanistic, less empirical models, whenever available. Specifically, fission gas release and swelling are modeled with the GRSIS algorithm, which is based on detailed tracking of fission gas bubbles within the metal fuel. Migration of the fuel constituents is modeled by means of thermo-transport theory. Fuel-clad chemical interaction models based on precipitation kinetics were developed for steady-state operation and transients. Finally, a transient intergranular creep-fracture model for the clad, which tracks the nucleation and growth of the cavities at the grain boundaries, was developed for and implemented in the code. Reducing the empiricism in the constitutive models should make it more acceptable to extrapolate FEAST-METAL to new fuel compositions and higher burnup, as envisioned in advanced sodium

  14. A new coupling of the 3D thermal-hydraulic code THYC and the thermo-mechanical code CYRANO3 for PWR calculations

    Among all parameters, the fuel temperature has a significant influence on the reactivity of the core, because of the Doppler effect on cross-sections. Most neutronic codes use a straightforward method to calculate an average fuel temperature used in their specific feed-back models. For instance, EDF's neutronic code COCCINELLE uses the Rowland's formula using the temperatures of the center and the surface of the pellet. COCCINELLE is coupled to the 3D thermal-hydraulic code THYC with calculates TDoppler with is standard thermal model. In order to improve the accuracy of such calculations, we have developed the coupling of our two latest codes in thermal-hydraulics (THYC) and thermo-mechanics (CYRANO3). THYC calculates two-phase flows in pipes or rod bundles and is used for transient calculations such as steam-line break, boron dilution accidents, DNB predictions, steam generator and condenser studies. CYRANO3 calculates most of the phenomena that take place in the fuel such as: 1) heat transfer induced by nuclear power; 2) thermal expansion of the fuel and the cladding; 3) release of gaseous fission's products; 4) mechanical interaction between the pellet and the cladding. These two codes are now qualified in their own field and the coupling, using Parallel Virtual Machine (PVM) libraries customized in an home-made-easy-to-use package called CALCIUM, has been validated on 'low' configurations (no thermal expansion, constant thermal characteristics) and used on accidental transients such as rod ejection and loss of coolant accident. (K.A.)

  15. Thermomechanical analysis of fuel rods during transitory events using the RAMONA and FETMA codes; Analisis termomecanico de barras combustibles durante eventos transitorios usando los codigos RAMONA y FETMA

    Hernandez L, H. [ININ, Departamento de Sistemas Nucleares, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)], e-mail: hector.hernandez@inin.gob.mx

    2009-10-15

    In National Institute of Nuclear Research, the fuel management system (FMS) has been used by long time to simulate the BWR operation in stationary state, as well as during a transitory event. To evaluate the thermomechanical behavior of a fuel element was created and interface between the FMS codes and the fuel element thermo mechanical analysis (FETMA) code properly developed and implemented. In this work, the results of thermomechanical behavior of fuel rods that compose the hot channel during the simulation of a transitory event of a BWR are shown. The transitory events considered in this work are a load rejection and failure in controller of feed water, which are events more important that can to occur in a BWR. The results show that during the developed conditions by both transitory events some failure is not presented in fuel rods. Also, that the transitory event of load rejection is more claimant in security terms that of controller failure of feed water. (Author)

  16. Modelling of the thermomechanical and physical processes in FR fuel pins using the GERMINAL code

    In the frame of the R and D on Fast Reactor mixed oxide fuels, CEA/DEC has developed the computer code GERMINAL for studying fuel pin thermal and mechanical behaviour, both during steady-state and incidental conditions, up to high burn-up (25 at%). The first part of this paper is devoted to the description of the main models: fuel evolution (central hole and porosity evolution, Plutonium redistribution, O/M radial profile, transient gas swelling, melting fuel behaviour, minor actinides production), high burn-up models (fission gas, volatile fission products and JOG formation), fuel-cladding heat transfer, fuel-cladding mechanical interaction. The second part gives some examples of calculation results taken from the GERMINAL validation data base (more than 40 experiments from PHENIX, PFR, CABRI reactors), with special emphasis on: local fission gas retention and global release, fuel geometry evolution, radial redistribution of plutonium for high burn-up fuels, solid and annular fuel behaviour during power ramps including fuel melting, helium formation from MA (Am and Np) doped homogeneous fuels. (author)

  17. Micromechanics-Based Structural Analysis (FEAMAC) and Multiscale Visualization within Abaqus/CAE Environment

    Arnold, Steven M.; Bednarcyk, Brett A.; Hussain, Aquila; Katiyar, Vivek

    2010-01-01

    A unified framework is presented that enables coupled multiscale analysis of composite structures and associated graphical pre- and postprocessing within the Abaqus/CAE environment. The recently developed, free, Finite Element Analysis--Micromechanics Analysis Code (FEAMAC) software couples NASA's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with Abaqus/Standard and Abaqus/Explicit to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. The Graphical User Interfaces (FEAMAC-Pre and FEAMAC-Post), developed through collaboration between SIMULIA Erie and the NASA Glenn Research Center, enable users to employ a new FEAMAC module within Abaqus/CAE that provides access to the composite microscale. FEA IAC-Pre is used to define and store constituent material properties, set-up and store composite repeating unit cells, and assign composite materials as sections with all data being stored within the CAE database. Likewise FEAMAC-Post enables multiscale field quantity visualization (contour plots, X-Y plots), with point and click access to the microscale i.e., fiber and matrix fields).

  18. Preliminary thermo-mechanical analysis of ITER breeding blanket

    Kikuchi, Shigeto; Kuroda, Toshimasa; Enoeda, Mikio [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    1999-01-01

    Thermo-mechanical analysis has been conducted on ITER breeding blanket taking into account thermo-mechanical characteristics peculiar to pebble beds. The features of the analysis are to adopt an elasto-plastic constitutive model for pebble beds and to take into account spatially varying thermal conductivity and heat transfer coefficient, especially in the Be pebble bed, depending on the stress. ABAQUS code and COUPLED TEMPERATURE-DISPLACEMENT procedure of the code are selected so that thermal conductivity is automatically calculated in each calculation point depending on the stress. The modified DRUCKER-PRAGER/Cap plasticity model for granular materials of the code is selected so as to deal with such mechanical features of pebble bed as shear failure flow and hydrostatic plastic compression, and capability of the model is studied. The thermal property-stress correlation used in the analysis is obtained based on the experimental results at FZK and the results of additional thermo-mechanical analysis performed here. The thermo-mechanical analysis of an ITER breeding blanket module has been performed for four conditions: case A; nominal case with spatial distribution of thermal conductivity and heat transfer coefficient in Be pebble bed depending on the stress, case B; constant thermal conductivity, case C; thermal conductivity = -20% of nominal case, and case D; thermal conductivity = +20% of nominal case. In the nominal case the temperature of breeding material (Li{sub 2}ZrO{sub 3}) ranges from 317degC to 554degC and the maximum temperature of Be pebble bed is 446degC. It is concluded that the temperature distribution is within the current design limits. Though the analyses performed here are preliminary, the results exhibit well the qualitative features of the pebble bed mechanical behaviors observed in experiments. For more detail quantitative estimates of the blanket performance, further investigation on mechanical properties of pebble beds by experiment

  19. Thermomechanical analysis of a fuel rod in a BWR reactor using the FUELSIM code; Analisis termomecanico de una barra de combustible de un reactor BWR utilizando el codigo FUELSIM

    Pantoja C, R. [Escuela Superior de Fisica y Matematicas, Departamento de Ingenieria Nuclear, IPN, Av. Instituto Politecnico Nacional s/n, Col. San Pedro Zacatenco, 07738 Mexico, D. F. (Mexico); Ortiz V, J.; Araiza M, E. [ININ, Departamento de Sistemas Nucleares, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)], e-mail: rapaca78@yahoo.com.mx

    2009-10-15

    The thermomechanical behaviour of a fuel rod exposed to irradiation is a complex process in which are coupled great quantity of interrelated physical-chemical phenomena, for that analysis of rod performance in the core of a nuclear power reactor is realized generally with computation codes that integrate several phenomena expected during the time life of fuel rod in the core. An application of this type of thermomechanical codes is to predict, inside certain reliability margin, the design parameters that would be required to adjust, in order to get a better economy or rod performance, for a systematic approach to the fuel design optimization. FUELSIM is a thermomechanical code based on the models of FRAPCON code, which was developed under auspice of Nuclear Regulatory Commission of USA. FUELSIM allows iterative calculations like part of its programming structure, allowing search of extreme cases of behaviour, probabilistic analysis (or statistical), parametric analysis (or sensibility) and also can include as entrance data to the uncertainties associated with production data, code parameters and associated models. In this work is reported a first analysis of thermomechanical performance of a typical fuel rod used in a BWR 5/6. Results of maximum temperatures are presented in the fuel center and of axial deformation, for the 10 axial nodes in that the active longitude of fuel rod was divided. (Author)

  20. Measurement and Prediction of the Thermomechanical Response of Shape Memory Alloy Hybrid Composite Beams

    Davis, Brian; Turner, Travis L.; Seelecke, Stefan

    2008-01-01

    An experimental and numerical investigation into the static and dynamic responses of shape memory alloy hybrid composite (SMAHC) beams is performed to provide quantitative validation of a recently commercialized numerical analysis/design tool for SMAHC structures. The SMAHC beam specimens consist of a composite matrix with embedded pre-strained SMA actuators, which act against the mechanical boundaries of the structure when thermally activated to adaptively stiffen the structure. Numerical results are produced from the numerical model as implemented into the commercial finite element code ABAQUS. A rigorous experimental investigation is undertaken to acquire high fidelity measurements including infrared thermography and projection moire interferometry for full-field temperature and displacement measurements, respectively. High fidelity numerical results are also obtained from the numerical model and include measured parameters, such as geometric imperfection and thermal load. Excellent agreement is achieved between the predicted and measured results of the static and dynamic thermomechanical response, thereby providing quantitative validation of the numerical tool.

  1. Integrating Moldflow and Abaqus in the Package Simulation Workflow

    Andreasson, Eskil; Persson, Leo; Jacobsson, Henrik; Nordgren, Johan

    2013-01-01

    Tetra Pak has used numerical simulation tools for plastic injection molding (Moldflow) and structural analysis (Abaqus/Implicit and Abaqus/Explicit) for many years. Today these two simulation tools are used independently of each other without any coupling. How these two disciplines can be combined to better predict the mechanical response of a polymer component is presented in this work. The manufacturing process, in this case injection molding, creates the mechanical properties of the produc...

  2. Development of computer codes to perform model calculations for thermomechanical interaction of rock salt with borehole liners in a HLW repository

    The principal objectives of the work are the development of computer codes with suitable material laws for rock salt and to perform model calculations on the thermomechanical phenomena in the near field of a radioactive waste repository. In particular the work was dealing with the following subjects: - Comparison of the computational capabilities of the finite element codes ADINA and MAUS (new version) by model calculations for the temperature test field 3. Thermally induced convergence rates of boreholes in a high level waste (HLW) repository. Investigation of the contact between salt and waste containers or borehole liners, and of the resulting pressure rise. Investigation of the effect of inhomogenities (anhydrite layers) in rock salt on the stress-strain field around a borehole in a HLW repository. Development of a material model for backfill material and performance of model calculations on the convergence of backfilled storage rooms or tunnels in rock salt. Development of a new version of the computer code MAUS by the Institut fuer Elektrische Anlagen und Energiewirtschaft of the RWTH-Aachen

  3. Samovar: a thermomechanical code for modeling of geodynamic processes in the lithosphere-application to basin evolution

    Elesin, Y; Gerya, T; Artemieva, Irina;

    2010-01-01

    We present a new 2D finite difference code, Samovar, for high-resolution numerical modeling of complex geodynamic processes. Examples are collision of lithospheric plates (including mountain building and subduction) and lithosphere extension (including formation of sedimentary basins, regions...... of extended crust, and rift zones). The code models deformation of the lithosphere with viscoelastoplastic rheology, including erosion/sedimentation processes and formation of shear zones in areas of high stresses. It also models steady-state and transient conductive and advective thermal processes including...... partial melting and magma transport in the lithosphere. The thermal and mechanical parts of the code are tested for a series of physical problems with analytical solutions. We apply the code to geodynamic modeling by examining numerically the processes of lithosphere extension and basin formation...

  4. Samovar: a thermomechanical code for modeling of geodynamic processes in the lithosphere-application to basin evolution

    Elesin, Y; Gerya, T; Artemieva, Irina; Thybo, Hans

    2010-01-01

    We present a new 2D finite difference code, Samovar, for high-resolution numerical modeling of complex geodynamic processes. Examples are collision of lithospheric plates (including mountain building and subduction) and lithosphere extension (including formation of sedimentary basins, regions of extended crust, and rift zones). The code models deformation of the lithosphere with viscoelastoplastic rheology, including erosion/sedimentation processes and formation of shear zones in areas of hig...

  5. Description of modelling to be implemented in the fuel rod thermomechanics code Cyrano3; Description des modeles a introduire dans le logiciel de thermomecanique du crayon combustible Cyrano3

    Baron, D.; Bouffioux, P.

    1993-06-01

    CYRANO3 is the new EDF thermomechanical code developed to evaluate the overall fuel rod behavior under irradiation. In that context, this paper presents the phenomena to be simulated and the correlations adopted for modelling purposes. The empirical models presented are taken from the CYRANO2 code and a compilation of the relevant literature. The present revision corrects and supplements version B on the basis of its use during the software coding phase from January 1991 to May 1993. (authors). figs., tabs., 120 refs.

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

    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...

  7. MCTP, a code for the thermo-mechanical analysis of a fuel rod of BWR type reactors (Neutron part); MCTP, un codigo para el analisis termo-mecanico de una barra combustible de reactores tipo BWR (Parte Neutronica)

    Hernandez L, H.; Ortiz V, J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: hhl@nuclear.inin.mx

    2003-07-01

    In the National Institute of Nuclear Research of Mexico a code for the thermo-mechanical analysis of the fuel rods of the BWR type reactors of the Nucleo electric Central of Laguna Verde is developed. The code solves the diffusion equation in cylindrical coordinates with several energy groups. The code, likewise, calculates the temperature distribution and power distribution in those fuel rods. The code is denominated Multi groups With Temperatures and Power (MCTP). In the code, the energy with which the fission neutrons are emitted it is divided in six groups. They are also considered the produced perturbations by the changes in the temperatures of the materials that constitute the fuel rods, the content of fission products, the uranium consumption and in its case the gadolinium, as well as the plutonium production. In this work there are present preliminary results obtained with the code, using data of operation of the Nucleo electric Central of Laguna Verde. (Author)

  8. Abaqus/Standard-based quantification of human cardiac mechanical properties

    Genet, Martin; Kuhl, Ellen; Guccione, Julius

    2016-01-01

    Computational modeling can provide critical insight into existing and potential new surgical procedures, medical or minimally-invasive treatments for heart failure, one of the leading causes of deaths in the world that has reached epidemic proportions. In this paper, we present our Abaqus/Standard-based pipeline to create subject-specific left ventricular models. We first review our generic left ventricular model, and then the personalization process based on magnetic resonance images. Identification of subject-specific cardiac material properties is done by coupling Abaqus/Standard to the python optimization library NL-Opt. Compared to previous studies from our group, the emphasis is here on the fully implicit solving of the model, and the two-parameter optimization of the passive cardiac material properties.

  9. Analysis of SMA Hybrid Composite Structures in MSC.Nastran and ABAQUS

    Turner, Travis L.; Patel, Hemant D.

    2005-01-01

    A thermoelastic constitutive model for shape memory alloy (SMA) actuators and SMA hybrid composite (SMAHC) structures was recently implemented in the commercial finite element codes MSC.Nastran and ABAQUS. The model may be easily implemented in any code that has the capability for analysis of laminated composite structures with temperature dependent material properties. The model is also relatively easy to use and requires input of only fundamental engineering properties. A brief description of the model is presented, followed by discussion of implementation and usage in the commercial codes. Results are presented from static and dynamic analysis of SMAHC beams of two types; a beam clamped at each end and a cantilever beam. Nonlinear static (post-buckling) and random response analyses are demonstrated for the first specimen. Static deflection (shape) control is demonstrated for the cantilever beam. Approaches for modeling SMAHC material systems with embedded SMA in ribbon and small round wire product forms are demonstrated and compared. The results from the commercial codes are compared to those from a research code as validation of the commercial implementations; excellent correlation is achieved in all cases.

  10. Impact-Contact Analysis of Prismatic Graphite Blocks Using Abaqus

    Graphite blocks are the important core components of the high temperature gas-cooled reactor. As these blocks are simply stacked in array, collisions among neighboring components may occur during earthquakes or accidents. The final objective of the research project is to develop a reliable seismic model of the stacked graphite blocks from which their behavior can be predicted and, thus, they are designed to have sufficient strength to maintain their structural integrity during the anticipated occurrences. The work summarized in this report is a first step toward the big picture and is dedicated to build a realistic impact-contact dynamics model of the graphite block using a commercial FEM package, Abaqus. The developed model will be further used to assist building a reliable lumped dynamics model of these stacked graphite components

  11. Thermomechanical treatment of steel

    Thermomechanical treatment is defined as a process in which a forming operation is carried out in the course of a treatment in order to improve the mechanical properties of a material. Several thermomechanical processes for the treatment of steel are described. (WBU)

  12. Thermo-mechanical interaction effects in foam cored sandwich panels-correlation between High-order models and Finite element analysis results

    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 or...

  13. Input Files and Procedures for Analysis of SMA Hybrid Composite Beams in MSC.Nastran and ABAQUS

    Turner, Travis L.; Patel, Hemant D.

    2005-01-01

    A thermoelastic constitutive model for shape memory alloys (SMAs) and SMA hybrid composites (SMAHCs) was recently implemented in the commercial codes MSC.Nastran and ABAQUS. The model is implemented and supported within the core of the commercial codes, so no user subroutines or external calculations are necessary. The model and resulting structural analysis has been previously demonstrated and experimentally verified for thermoelastic, vibration and acoustic, and structural shape control applications. The commercial implementations are described in related documents cited in the references, where various results are also shown that validate the commercial implementations relative to a research code. This paper is a companion to those documents in that it provides additional detail on the actual input files and solution procedures and serves as a repository for ASCII text versions of the input files necessary for duplication of the available results.

  14. Modelling of friction anisotropy of deepdrawing sheet in ABAQUS/EXPLICIT

    F. Stachowicz; Trzepieciński, T.

    2010-01-01

    This paper presents the experimental and numerical results of rectangular cup drawing of steel sheets. The aim of the experimental study was to analyze material behavior under deformation. The received results were further used to verify the results from numerical simulation by taking friction and material anisotropy into consideration. A 3D parametric finite element (FE) model was built using the FE-package ABAQUS/Standard. ABAQUS allows analyzing physical models of real processes putting s...

  15. Analysis of SMA hybrid composite structures using commercial codes

    Turner, Travis L.; Patel, Hemant D.

    2004-07-01

    A thermomechanical model for shape memory alloy (SMA) actuators and SMA hybrid composite (SMAHC) structures has been recently implemented in the commercial finite element codes MSC.Nastran and ABAQUS. The model may be easily implemented in any code that has the capability for analysis of laminated composite structures with temperature dependent material properties. The model is also relatively easy to use and requires input of only fundamental engineering properties. A brief description of the model is presented, followed by discussion of implementation and usage in the commercial codes. Results are presented from static and dynamic analysis of SMAHC beams of two types; a beam clamped at each end and a cantilevered beam. Nonlinear static (post-buckling) and random response analyses are demonstrated for the first specimen. Static deflection (shape) control is demonstrated for the cantilevered beam. Approaches for modeling SMAHC material systems with embedded SMA in ribbon and small round wire product forms are demonstrated and compared. The results from the commercial codes are compared to those from a research code as validation of the commercial implementations; excellent correlation is achieved in all cases.

  16. Thermomechanical analysis of fast-burst reactors

    Fast-burst reactors are designed to provide intense, short-duration pulses of neutrons. The fission reaction also produces extreme time-dependent heating of the nuclear fuel. An existing transient-dynamic finite element code was modified specifically to compute the time-dependent stresses and displacements due to thermal shock loads of reactors. Thermomechanical analysis was then applied to determine structural feasibility of various concepts for an EDNA-type reactor and to optimize the mechanical design of the new SPR III-M reactor

  17. Thermo-Mechanical Simulation of Brake Disc Frictional Character by Moment of Inertia

    Fei Gao

    2014-01-01

    The distribution of temperatures gradient and thermal stress of brake disc has been simulated by FEM code to make brake disc thermal stress more homogenously. In this study, using moment of inertia to simulate the realistic brake process instead of theoretically predefines the train deceleration rate, nonlinear deceleration rate and thermo-mechanical behavior has been revealed. The FEM models build upon LS-DYNA® thermo-mechanical code and contact algorithm. Non-uniform temperature alone disc ...

  18. Toward high-speed 3D nonlinear soft tissue deformation simulations using Abaqus software.

    Idkaidek, Ashraf; Jasiuk, Iwona

    2015-12-01

    We aim to achieve a fast and accurate three-dimensional (3D) simulation of a porcine liver deformation under a surgical tool pressure using the commercial finite element software Abaqus. The liver geometry is obtained using magnetic resonance imaging, and a nonlinear constitutive law is employed to capture large deformations of the tissue. Effects of implicit versus explicit analysis schemes, element type, and mesh density on computation time are studied. We find that Abaqus explicit and implicit solvers are capable of simulating nonlinear soft tissue deformations accurately using first-order tetrahedral elements in a relatively short time by optimizing the element size. This study provides new insights and guidance on accurate and relatively fast nonlinear soft tissue simulations. Such simulations can provide force feedback during robotic surgery and allow visualization of tissue deformations for surgery planning and training of surgical residents. PMID:26530842

  19. Modelling and finite element simulation for FDSC multi-point forming based on ABAQUS

    Weiwei, Wan; Binbin, Jia; Tingting, Sun; He, Di; Chen, Zhao

    2015-01-01

    This paper introduces the modeling and FEM simulation of FDSC Multi-Point Forming based on ABAQUS. Python is used as programming languages to secondary develop the software and to establish a simulation platform. An additional module was developed for the automatic modeling with the functions of: (a) basic parameters input such as material performance, plate size (b) rapid assembly of MPF punches and sheet automatically (c)automatic definition of the analytical step and the output of variable...

  20. Developing an Abaqus *HYPERFOAM Model for M9747 (4003047) Cellular Silicone Foam

    Siranosian, Antranik A. [Los Alamos National Laboratory; Stevens, R. Robert [Los Alamos National Laboratory

    2012-04-26

    This report documents work done to develop an Abaqus *HYPERFOAM hyperelastic model for M9747 (4003047) cellular silicone foam for use in quasi-static analyses at ambient temperature. Experimental data, from acceptance tests for 'Pad A' conducted at the Kansas City Plant (KCP), was used to calibrate the model. The data includes gap (relative displacement) and load measurements from three locations on the pad. Thirteen sets of data, from pads with different serial numbers, were provided. The thirty-nine gap-load curves were extracted from the thirteen supplied Excel spreadsheets and analyzed, and from those thirty-nine one set of data, representing a qualitative mean, was chosen to calibrate the model. The data was converted from gap and load to nominal (engineering) strain and nominal stress in order to implement it in Abaqus. Strain computations required initial pad thickness estimates. An Abaqus model of a right-circular cylinder was used to evaluate and calibrate the *HYPERFOAM model.

  1. Coupled thermomechanical modeling using dissimilar geometries in arpeggio.

    Kostka, Timothy D.; Templeton, Jeremy Alan

    2010-11-01

    Performing coupled thermomechanical simulations is becoming an increasingly important aspect of nuclear weapon (NW) safety assessments in abnormal thermal environments. While such capabilities exist in SIERRA, they have thus far been used only in a limited sense to investigate NW safety themes. An important limiting factor is the difficulty associated with developing geometries and meshes appropriate for both thermal and mechanical finite element models, which has limited thermomechanical analysis to simplified configurations. This work addresses the issue of how to perform coupled analyses on models where the underlying geometries and associated meshes are different and tailored to their relevant physics. Such an approach will reduce the model building effort and enable previously developed single-physics models to be leveraged in future coupled simulations. A combined-environment approach is presented in this report using SIERRA tools, with quantitative comparisons made between different options in SIERRA. This report summarizes efforts on running a coupled thermomechanical analysis using the SIERRA Arpeggio code.

  2. Finite Element Analysis of Progressive Failure and Strain Localization of Carbon Fiber/Epoxy Composite Laminates by ABAQUS

    Liu, P. F.; Yang, Y. H.; Gu, Z. P.; Zheng, J. Y.

    2015-12-01

    Interaction mechanism between the intralaminar damage and interlaminar delamination of composite laminates is always a challenging issue. It is important to consider the progressive failure and strain softening behaviors simultaneously during the damage modeling and numerical simulation of composites using FEA. This paper performs three-dimensional finite element analysis of the progressive failure and strain localization of composites using FEA. An intralaminar progressive failure model based on the strain components is proposed and the nonlinear cohesive model is used to predict the delamination growth. In particular, the nonlocal integral theory which introduces a length scale into the governing equations is used to regularize the strain localization problems of composite structures. Special finite element codes are developed using ABAQUS to predict the intralaminar and interlaminar damage evolution of composites simultaneously. The carbon fiber/epoxy composite laminates with a central hole demonstrates the developed theoretical models and numerical algorithm by discussing the effects of the mesh sizes and layups patterns. It is shown the strain localization problem can be well solved in the progressive failure analysis of composites when the energy dissipation due to the damage of the fiber, matrix and interface occurs at a relatively wide area.

  3. A local model for the thermomechanical conditions in friction stir welding

    Schmidt, H.; Hattel, J.

    2005-01-01

    The conditions under which the deposition process in friction stir welding is successful are not fully understood. However, it is known that only under specific thermomechanical conditions does a weld formation occur. If these conditions are not present, void formation will occur leading to a faulty weld. The objective of the present work is to analyse the primary conditions under which the cavity behind the tool is filled. For this, a fully coupled thermomechanical three-dimensional FE model has been developed in ABAQUS/Explicit using the arbitrary Lagrangian-Eulerian formulation and the Johnson-Cook material law. The model accounts for the compressibility by including the elastic response of the aluminium matrix. The contact forces are modelled by Coulomb's Law of friction, making the contact condition highly solution dependent. Furthermore, separation between the workpiece and the tool is allowed. This is often neglected in other models. Once non-recoverable separation is estimated by the model, a void develops. This is suggested as a preliminary criterion for evaluating the success of the deposition process. Of special interest is the contact condition along the tool/matrix interface, which controls the efficiency of the deposition process. In most models presented previously in the literature, the material flow at the tool interface is prescribed as boundary conditions. In all other contact models, the material is forced to keep contact with the tool. Therefore, the models are unable to predict when the suitable thermomechanical conditions and welding parameters are present. In the present work, the quasi-stationary thermomechanical state in the workpiece is established by modelling the dwell and weld periods. The different thermomechanical states in the colder, stiffer far-field matrix and the hotter, softer near-field matrix (under the tool) result in contact at the tool/matrix interface, thus, no void formation is observed. The steady-state model results

  4. Quasi-static analysis of leg mating unit with ABAQUS/Explicit%基于ABAQUS/Explicit的桩腿耦合缓冲器准静态分析

    夏天; 张世联; 郑轶刊; 彭大炜

    2011-01-01

    The Leg Mating Unit with rubber-metal pads as a buffer is applied in offshore superstructure installation to reduce mating force and accommodate large relative displacement. In design, much attention should be paid to the geometry, material and boundary nonlinearity involved in the LMU structure. In this paper, the 3-D FE model is created and its vertical and horizonrtal load cases are simulated with quasistatic method by ABAQUS/Explicit. The results are interpreted in terms of energy, contact, stiffness, stress and strain, which are reasonable enough to indicate that the LMU structure has strong strength and the simulating method employed here are feasible. Furthermore, some suggestions are given to improve the present structure. The results in the paper are helpful to the design optimization of the leg mating unit.%桩腿耦合缓冲器在应用中主要起减小撞击力和限制上下结构相对位移的作用.在设计时,必须考虑到橡胶材料的大变形、橡胶-钢的接触和摩擦问题,它具有几何、材料和边界的三种非线性.通过结构非线性有限元软件ABAQUS/Explicit建立了桩腿耦合缓冲器的三维体单元模型,用基于中心差分法的准静态法,对其在水平和垂直两种工况下的准静力变形过程进行了数值仿真,从能量、接触、刚度与吸能以及应力应变等各方面对计算结果及其合理性进行了分析,并针对现有结构尺寸提出了改进建议.分析表明使用准静态分析方法是可行的,对桩腿耦合缓冲器的优化设计具有一定参考价值.

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

    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)

  6. Thermomechanical properties of hafnium hydride

    Fine bulk samples of delta-phase Hf hydride with various hydrogen contents (CH) ranging from 1.62 to 1.72 in the atomic ratio (H/Hf) were prepared, and their thermomechanical properties were characterized. At room temperature, the sound velocity and Vickers hardness were measured. The elastic modulus was calculated from the measured sound velocity. In the temperature range from room temperature to 673 K, the thermal expansion was measured by using a dilatometer, and the linear thermal expansion coefficient was calculated. Empirical equations describing the thermomechanical properties of Hf hydride as a function of CH were proposed. (author)

  7. A coupled thermo-mechanical model of friction stir welding

    Veljić Darko M.

    2012-01-01

    Full Text Available A coupled thermo-mechanical model was developed to study the temperature fields, the plunge force and the plastic deformations of Al alloy 2024-T351 under different rotating speed: 350, 400 and 450 rpm, during the friction stir welding (FSW process. Three-dimensional FE model has been developed in ABAQUS/Explicit using the arbitrary Lagrangian-Eulerian formulation, the Johnson-Cook material law and the Coulomb’s Law of friction. Numerical results indicate that the maximum temperature in the FSW process is lower than the melting point of the welding material. The temperature filed is approximately symmetrical along the welding line. A lower plastic strain region can be found near the welding tool in the trailing side on the bottom surface. With increasing rotation speed, the low plastic strain region is reduced. When the rotational speed is increased, the plunge force can be reduced. Regions with high equivalent plastic strains are observed which correspond to the nugget and the flow arm.

  8. Dynamic Analysis of the Arch Concrete Dam under Earthquake Force with ABAQUS

    M.A. Lotfollahi Yaghin

    2008-01-01

    Full Text Available In this study, the dynamical behavior of arch concrete dams has been analyzed by finite element method. The case study is Karoon-1 (shahid Abbaspoor, double curvature arch dam with the height of 200 m. This dam is considered as one of the most complex dams because of different external and internal radius and angles, also, asymmetrical center of external and internal archs in different levels. So, by geometrical dimensions of the mentioned dam from related designing maps and also its mechanical and physical properties, dam without supports and dam with rock supports are modeled by ABAQUS finite element software. According to dynamical analysis results, have been calculated the time history of main stress, displacement of the dam in crest and river bed level and also, their maximum values in earthquake time duration have been compared and investigated.

  9. Application of Abaqus to analysis of the temperature field in elements heated by moving heat sources

    W. Piekarska

    2010-10-01

    Full Text Available Numerical analysis of thermal phenomena occurring during laser beam heating is presented in this paper. Numerical models of surface andvolumetric heat sources were presented and the influence of different laser beam heat source power distribution on temperature field wasanalyzed. Temperature field was obtained by a numerical solution the transient heat transfer equation with activity of inner heat sources using finite element method. Temperature distribution analysis in welded joint was performed in the ABAQUS/Standard solver. The DFLUXsubroutine was used for implementation of the movable welding heat source model. Temperature-depended thermophysical properties for steelwere assumed in computer simulations. Temperature distribution in laser beam surface heated and butt welded plates was numericallyestimated.

  10. Numerical modelling of thermal phenomena in laser beam and hybrid welding processes using Abaqus FEA

    W. Piekarska

    2011-04-01

    Full Text Available This paper concerns numerical analysis of thermal phenomena accompanying laser beam and laser-arc hybrid welding processes.Temperature field was obtained on the basis of the solution into energy conservation equation with Fourier law using finite elementmethod. ABAQUS/Standard solver was used for calculations. Electric arc and laser beam heat sources were described respectively by“double ellipsoidal” heat source and Gaussian distribution with assumption of linear decrease of heat source power intensity with material penetration deep. Heat source movement along welded plate was obtained using DFLUX subroutine. Thermo-physical parametersdependant on temperature as well as latent heat of fusion were taken into account in FE analysis. The results of calculations includetemperature field in rectangular elements butt welded by a single laser beam and hybrid laser-arc technique.

  11. Thermomechanical analysis of nuclear fuel elements

    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)

  12. Thermomechanical properties of selected shales

    The experimental work discussed in this report is part of an ongoing program concerning evaluation of sedimentary and other rock types as potential hosts for a geologic repository. The objectives are the development of tools and techniques for repository characterization and performance assessment in a diversity of geohydrologic settings. This phase of the program is a laboratory study that investigates fundamental thermomechanical properties of several different shales. Laboratory experiments are intrinsically related to numerical modeling and in situ field experiments, which together will be used for performance assessment

  13. Thermomechanical properties of selected shales

    Hansen, F.D.; Vogt, T.J.

    1987-08-01

    The experimental work discussed in this report is part of an ongoing program concerning evaluation of sedimentary and other rock types as potential hosts for a geologic repository. The objectives are the development of tools and techniques for repository characterization and performance assessment in a diversity of geohydrologic settings. This phase of the program is a laboratory study that investigates fundamental thermomechanical properties of several different shales. Laboratory experiments are intrinsically related to numerical modeling and in situ field experiments, which together will be used for performance assessment.

  14. SIMULATION OF COMPLEX THERMOMECHANICAL FATIGUE

    R.Bardenheier; G.Rogers

    2004-01-01

    Two different types of experimental techniques to perform non-isothermal, unicxial and biaxial fatigue testa were described. A new miniaturised electrothermalmechanical test rig was presented and discussed. It enables testing of small specimens under complex thermomechanical loading conditions. In order to cope with the simulation of well defined biaxial proportional and non-proportional loadings with in-phase and out-of-phase superposition of thermal loads a cruciform biaxial fatigue testing machine has been developed. Special design features of both machines, and the specimens tested, as well as typical test results were discussed.

  15. Thermohydraulics design and thermomechanics analysis of two European breeder blanket concepts for DEMO. Pt. 1 and Pt. 2. Pt. 1: BOT helium cooled solid breeding blanket. Pt. 2: Dual coolant self-cooled liquid metal blanket

    Two different breeding blanket concepts are being elaborated at Forschungszentrum Karlsruhe within the framework of the DEMO breeding blanket development, the concept of a helium cooled solid breeding blanket and the concept of a self-cooled liquid metal blanket. The breeder material used in the first concept is Li4SiO4 as a pebble bed arranged separate from the beryllium pebble bed, which serves as multiplier. The breeder material zone is cooled by several toroidally-radially configurated helium cooling plates which, at the same time, act as reinforcements of the blanket structures. In the liquid metal blanket concept lead-lithium is used both as the breeder material and the coolant. It flows at low velocity in poloidal direction downwards and back in the blanket front zone. In both concepts the First Wall is cooled by helium gas. This report deals with the thermohydraulics design and thermomechanics analysis of the two blanket concepts. The performance data derived from the Monte-Carlo computations serve as a basis for the design calculations. The coolant inlet and outlet temperatures are chosen with the design criteria and the economics aspects taken into account. Uniform temperature distribution in the blanket structures can be achieved by suitable branching and routing of the coolant flows which contributes to reducing decisively the thermal stress. The computations were made using the ABAQUS computer code. The results obtained of the stresses have been evaluated using the ASME code. It can be demonstrated that all maximum values of temperature and stress are below the admissible limit. (orig.)

  16. 基于ABAQUS?R的复合材料跨尺度失效分析软件开发

    薛斌; 李星

    2015-01-01

    复合材料跨尺度失效理论是近些年提出的一类基于物理失效模式的强度理论,它从细观层面判定纤维和基体的失效,在分析复合材料性能匹配和耐久性方面有独特的优势. 提出了一种新的跨尺度失效判定准则,利用Abaqus?R的内嵌Python脚本语言开发了复合材料跨尺度失效分析软件CMFAS,编制了图形用户界面(GUI)进行人机交互,实现了代表体积单元(RVE)参数化建模及后处理、应力放大系数矩阵生成、失效准则临界值求解和损伤演化处理等一系列功能,最终生成Abaqus?R子程序文件USDFLD和VUSDFLD.%Composite multiscale failure theory is a newly proposed category of strength criteria, based on mechanical failure modes. In this theory, fiber and matrix failure are determined in meso level, which has special advantage in analyzing material property matching and durability. A new multiscale failure criteria was proposed, CMFAS (Composite Multiscale Failure Analysis Software) was developed using Python scripting language embedded in Abaqus?R . In CMFAS, GUI (Graphic User Interface) was compiled to realize human-computer interaction, RVE (Representative Volume Element) parametric modeling and post processing, stress amplification factors generation, failure criteria critical value solving and damage evolution were automatically accomplished, finally Abaqus?R subroutine files USDFLD and VUSDFLD were given.

  17. Simulation of thermomechanical fatigue in solder joints

    Fang, H.E.; Porter, V.L.; Fye, R.M.; Holm, E.A. [Sandia National Labs., Albuquerque, NM (United States)

    1997-12-31

    Thermomechanical fatigue (TMF) is a very complex phenomenon in electronic component systems and has been identified as one prominent degradation mechanism for surface mount solder joints in the stockpile. In order to precisely predict the TMF-related effects on the reliability of electronic components in weapons, a multi-level simulation methodology is being developed at Sandia National Laboratories. This methodology links simulation codes of continuum mechanics (JAS3D), microstructural mechanics (GLAD), and microstructural evolution (PARGRAIN) to treat the disparate length scales that exist between the macroscopic response of the component and the microstructural changes occurring in its constituent materials. JAS3D is used to predict strain/temperature distributions in the component due to environmental variable fluctuations. GLAD identifies damage initiation and accumulation in detail based on the spatial information provided by JAS3D. PARGRAIN simulates the changes of material microstructure, such as the heterogeneous coarsening in Sn-Pb solder, when the component`s service environment varies.

  18. In the Structural Modal Analysis Application of ABAQUS Based on Python%基于Python的ABAQUS在结构模态分析上的应用

    禹文涛; 徐航; 梁军勇

    2012-01-01

    The python script interface is provided by ABAQUS for programmers aimed at second-developed ABAQUS. Executing python script at ABAQUS environment, may automatically-setting-up, repeat and modify models and analysis tasks expediently, may realize parametric study and access output database, etc. In this paper, a coupling as an example to introduce based on the ABAQUS Python in structural modal analysis application.%ABAQUS为二次开发用户提供了Python脚本接口。在ABAQUS环境下执行Python脚本,可方便地实现自动化创建、重复、修改模型及分析任务,实现参数化研究,访问结果数据库等功能。以某联轴器为例,介绍了基于Python的ABAQUS在结构模态分析上的应用。

  19. 钢包预热过程热应力影响因子及预报模型%Classification of thermomechanical impact factors and prediction model for ladle preheating

    金胜利; Harald Harmuth; Dietmar Gruber; Thomas Auer; 李亚伟

    2011-01-01

    Linear elastic models were established by means of finite element code ABAQUS to simulate the thermomechanical behavior of steel ladle during preheating. The impact factors of ladle lining thickness and material properties on the maximum stress at steel ladle linings and end temperature at the steel shell were determined. Prediction models were built with partial least squares algorithm based on the above simulation results. The results show that the material properties of working lining plays a major role in the maximum compressive stress, maximum tensile stress and end temperature whether it includes an insulation or not. Compared with the ladle without an insulation, the importance of permanent lining to the maximum stress is reduced significantly by using the insulation.%运用有限元软件ABAQUS建立钢包包衬的线性弹性模型,模拟钢包预热过程包衬的热应力,分析包衬厚度及其材料物理性能对包衬内最大热应力和钢壳表面温度的影响;采用偏最小二乘法建立包衬厚度及材料物理性能与包衬内最大热应力、钢壳表面温度间的预报模型.结果表明,工作衬材料物理性能对包衬最大应力和钢壳表面温度起主要影响作用;较之于无绝热衬,有绝热衬钢包永久衬材料物理性能对钢包热应力和钢壳表面温度的影响作用显著降低.

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

    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 Li2TiO3 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 Li2TiO3 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 328degC in

  1. A Transversely Isotropic Thermo-mechanical Framework for Oil Shale

    Semnani, S. J.; White, J. A.; Borja, R. I.

    2014-12-01

    The present study provides a thermo-mechanical framework for modeling the temperature dependent behavior of oil shale. As a result of heating, oil shale undergoes phase transformations, during which organic matter is converted to petroleum products, e.g. light oil, heavy oil, bitumen, and coke. The change in the constituents and microstructure of shale at high temperatures dramatically alters its mechanical behavior e.g. plastic deformations and strength, as demonstrated by triaxial tests conducted at multiple temperatures [1,2]. Accordingly, the present model formulates the effects of changes in the chemical constituents due to thermal loading. It is well known that due to the layered structure of shale its mechanical properties in the direction parallel to the bedding planes is significantly different from its properties in the perpendicular direction. Although isotropic models simplify the modeling process, they fail to accurately describe the mechanical behavior of these rocks. Therefore, many researchers have studied the anisotropic behavior of rocks, including shale [3]. The current study presents a framework to incorporate the effects of transverse isotropy within a thermo-mechanical formulation. The proposed constitutive model can be readily applied to existing finite element codes to predict the behavior of oil shale in applications such as in-situ retorting process and stability assessment in petroleum reservoirs. [1] Masri, M. et al."Experimental Study of the Thermomechanical Behavior of the Petroleum Reservoir." SPE Eastern Regional/AAPG Eastern Section Joint Meeting. Society of Petroleum Engineers, 2008. [2] Xu, B. et al. "Thermal impact on shale deformation/failure behaviors---laboratory studies." 45th US Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Association, 2011. [3] Crook, AJL et al. "Development of an orthotropic 3D elastoplastic material model for shale." SPE/ISRM Rock Mechanics Conference. Society of Petroleum Engineers

  2. Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration and noise reduction

    Yi, Guilian; Sui, Yunkang; Du, Jiazheng

    2011-06-01

    To reduce vibration and noise, a damping layer and constraint layer are usually pasted on the inner surface of a gearbox thin shell, and their thicknesses are the main parameters in the vibration and noise reduction design. The normal acceleration of the point on the gearbox surface is the main index that can reflect the vibration and noise of that point, and the normal accelerations of different points can reflect the degree of the vibration and noise of the whole structure. The K-S function is adopted to process many points' normal accelerations as the comprehensive index of the vibration characteristics of the whole structure, and the vibration acceleration level is adopted to measure the degree of the vibration and noise. Secondary development of the Abaqus preprocess and postprocess on the basis of the Python scripting programming automatically modifies the model parameters, submits the job, and restarts the analysis totally, which avoids the tedious work of returning to the Abaqus/CAE for modifying and resubmitting and improves the speed of the preprocess and postprocess and the computational efficiency.

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

    Tsai, F.C. [M& O/Woodward Clyde Federal Services, Las Vegas, NV (United States)

    1996-04-01

    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.

  4. Thermomechanical treatment of heat-resisting alloys

    Different types of thermomechanical treatment (TMT) are considered in the review. Three schemes which are used for heat resistant ageing alloys are singled out and described in detail: high-temperature thermomechanical treatment (HTMT), mechanico-thermal treatment (MTT) and low-temperature thermomechanical treatment (LTMT). Special attention is paid to perspective LTMT including warm deformation. It is shown that the application of the TMT to concrete alloys permits to increase the strength characteristics in a certain temperature range of the product exploitation without considerable plasticity loss. TMT with the use.of warm deformation in two-phase region looks like the most perspective treatment increasing strength properties, resistance against fatigue destruction and decreasing the sensitivity to the cut

  5. Numerical modeling and prediction of thermomechanical degradation of power electronic packaging

    Baazaoui, Ahlem; Dalverny, Olivier; Alexis, Joël; Karama, Moussa

    2013-01-01

    This work aims at numerical thermomechanical studies of two types of high temperature silver connections elaborated at low temperatures, the transient liquid phase bonding (TLPB) of Ag-In and silver nanoparticles sintering, using test vehicles representing the final packaging assemblies of diamond components. The simulation is performed using a finite element code on 2D and 3D assemblies. The stress distribution in the assemblies and in the two die-attachments was studied during thermal cycli...

  6. 基于ABAQUS的连杆疲劳分析%Fatigue Analysis of Connecting Rods Based on ABAQUS

    谈梅兰; 武国玉; 梁福祥

    2013-01-01

    为了全面地考察连杆受到的动态疲劳载荷,在发动机标定工况下,利用转动惯量法对连杆进行了运动学和动力学分析.基于临界平面法,用ABAQUS软件进行二次开发得到了连杆的疲劳计算模块.采用有限元方法分析计算了连杆的疲劳寿命.整个过程是在ABAQUS软件中用Python语言编程来实现的.数值计算结果显示,与传统的最大拉压工况结果相比,在发动机标定工况下得到的计算结果能比较全面地反映连杆的疲劳特性,表明该数值计算方法正确,二次开发程序可行.%In order to investigate the dynamic fatigue loads of a connecting rod under engine calibration conditions more fully, the analysis of kinematics and dynamics of the connecting rod was carried out using the rotational inertia method. With the help of the critical plane method, fatigue calculation module was redeveloped based on ABAQUS. The fatigue life was given through finite element analysis of the connecting rod. The whole process was achieved by Python programming language in the ABAQUS software. The developed method herein is able to reflect the connecting rod's fatigue properties more fully by the comparison of numerical results obtained in the engine calibration conditions with the traditional results of the maximum tensile and compressive conditions. It is also shown that the numerical calculation is correct, the redevelopment of the program is feasible.

  7. Multiscale thermomechanical analysis of multiphase materials

    Yadegari Varnamkhasti, S.

    2015-01-01

    The thermomechanical simulation of materials with evolving, multiphase microstructures poses various modeling and numerical challenges. For example, the separate phases in a multiphase microstructure can interact with each other during thermal and/or mechanical loading, the effect of which is signif

  8. Thermomechanics of composite structures under high temperatures

    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...

  9. FGM elastoplastic analysis under thermomechanical loading

    In this research, thick walled FGM spherical pressure vessels under internal pressure and temperature difference were studied. Material parameters were considered to vary as a power functions. In order to clarify the role of material parameters, several different materials with different parameters have been used. Different combinations of the internal pressure and temperature gradient loading were applied and their effects on the yield onset location, kinds of stresses and the role of temperature gradient, were studied. Linear kinematic hardening was supposed and the pressure vessel behavior under constant internal; pressure and cyclic temperature gradient, was obtained. -- Highlights: • Elastic solution of an FGM spherical pressure vessel under thermomechanical loading was obtained. • Yield onset under different thermomechanical loading and material properties were obtained. • Linear kinematic hardening was used and plastic strain and stress equations were developed. • Bree's interaction diagram was obtained for two different FGM pressure vessel

  10. Introduction to nonlinear thermomechanics of solids

    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.

  11. Thermomechanical Stresses in Fullerenes at Nanotube

    Pugno, Nicola M.

    2008-01-01

    The thermomechanical stresses acting between a nanotube and fullerenes encapsulated on it are computed. After a general formulation, based on elasticity, we have applied the analysis to C82000040(10,10) or C60000040(10,10) peapods finding stresses in the gigapascal range or vanishing, respectively. The analysis suggests that a thermal control could be used to produce smart fullerenes at nanotube systems, for example, as two-stage nanovectors for drug delivery.

  12. Thermomechanical Stresses in Fullerenes at Nanotube

    Nicola M. Pugno

    2008-01-01

    Full Text Available The thermomechanical stresses acting between a nanotube and fullerenes encapsulated on it are computed. After a general formulation, based on elasticity, we have applied the analysis to C82000040(10,10 or C60000040(10,10 peapods finding stresses in the gigapascal range or vanishing, respectively. The analysis suggests that a thermal control could be used to produce smart fullerenes at nanotube systems, for example, as two-stage nanovectors for drug delivery.

  13. 基于Abaqus/explicit的钛合金高速切削切削力模拟研究%Simulation Study on Cutting Force During High Speed Machining Titanium Alloy Based on Abaqus/explicit

    芮执元; 李川平; 郭俊锋; 冯瑞成

    2011-01-01

    The aim of this research was to investigate cutting force during high speed machining titanium alloy. Johnson- Cook materials model and fracture criterion of commercial finite element software Abaqus was used to simulate high speed machining Ti6Al4V. It was Analyzed that The influence of the cutting parameters (including feed rate, cutting depth, cutting speed) on the cutting forces. The results shown that cutting force, feed force, specific cutting force and specific feed force reduced with increases in cutting speed, cutting force, feed force increased and specific cutting force, specific feed force reduced with increases in feed rate.%针对高速切削钛合金时切削力的问题,利用有限元分析软件Abaqus的Johnson-Cook材料模型及Johnson-Cook断裂准则,对钛合金高速切削切削力进行了仿真研究,分析钛合金高速切削加工过程中各切削参数(包括进给量、切削深度和切削速度)对切削力的影响.结果表明,切削力、进给力、单位面积切削力和单位面积进给力都随速度的增大而减小;但随着进给速度的增大,切削力和进给力都增大,而单位面积的切削力和进给力都减小.

  14. Thermomechanical evaluation of the fuel assemblies fabricated in the ININ; Evaluacion termomecanica de los ensambles combustibles fabricados en el ININ

    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)

  15. Theoretical approach to the WWER core thermomechanical modelling

    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

  16. Thermomechanical Properties of TiNi Shape Memory Alloy

    Tobushi, H.; Ikai, A; Yamada, S.; K.Tanaka; Lexcellent, C.

    1996-01-01

    The thermomechanical properties of shape memory effect and superelasticity due to the martensitic transformation and the R-phase transformation of TiNi shape memory alloy were investigated experimentally. The transformation Une, recovery stress and fatigue property due to both transformations were discussed for cyclic deformation. The thermomechanical properties due to the R-phase transformation were excellent for deformation with high cycles.

  17. Interfacing VPSC with finite element codes. Demonstration of irradiation growth simulation in a cladding tube

    This Milestone report shows good progress in interfacing VPSC with the FE codes ABAQUS and MOOSE, to perform component-level simulations of irradiation-induced deformation in Zirconium alloys. In this preliminary application, we have performed an irradiation growth simulation in the quarter geometry of a cladding tube. We have benchmarked VPSC-ABAQUS and VPSC-MOOSE predictions with VPSC-SA predictions to verify the accuracy of the VPSCFE interface. Predictions from the FE simulations are in general agreement with VPSC-SA simulations and also with experimental trends.

  18. Interfacing VPSC with finite element codes. Demonstration of irradiation growth simulation in a cladding tube

    Patra, Anirban [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-23

    This Milestone report shows good progress in interfacing VPSC with the FE codes ABAQUS and MOOSE, to perform component-level simulations of irradiation-induced deformation in Zirconium alloys. In this preliminary application, we have performed an irradiation growth simulation in the quarter geometry of a cladding tube. We have benchmarked VPSC-ABAQUS and VPSC-MOOSE predictions with VPSC-SA predictions to verify the accuracy of the VPSCFE interface. Predictions from the FE simulations are in general agreement with VPSC-SA simulations and also with experimental trends.

  19. Coupling of STOMP and ABAQUS for Hydro-Geomechanical Modeling of Fluid Flow and Rock Deformation Associated with Subsurface CO2 Injection

    Carroll, K. C.; Nguyen, B. N.; Fang, Y.; Richmond, M. C.; Murray, C. J.

    2011-12-01

    Geomechanical alteration of porous media is generally ignored for most shallow subsurface applications, whereas CO2 injection, migration, and trapping in deep saline aquifers will be controlled by coupled multifluid flow, energy transfer, geomechanical, and geochemical processes. The accurate assessment of the risks associated with potential leakage of injected CO2 and the design of effective injection systems requires that we represent these coupled processes within numerical simulators. The objective of this study was to examine the coupling of hydraulic and geomechanical processes for simulation of CO2 injection into the subsurface for carbon sequestration. The impact of nonisothermal multifluid flow and porous media deformation mechanics on CO2 migration and storage was evaluated. We present a sequentially coupled approach for multifluid and geomechanical simulation using STOMP and ABAQUS that has been developed and validated through comparison to the solutions for benchmark problems that were solved with a coupled TOUGH-FLAC simulator. The poroelastic model was implemented with user-subroutines in ABAQUS. We also compare the STOMP-ABAQUS simulator to a new version of STOMP that includes the fully coupled poroelastic simulation within the multifluid flow and transport simulator. The poroelastic model computes stiffness, stresses, and strains using aqueous and gas pressures as well as saturations from STOMP output, and provides STOMP with the updated permeability, porosity, and capillary pressure over time during the simulation. The hydraulic only (uncoupled from mechanics) simulation and the hydrogeomechanical (coupled) simulation results using STOMP-ABAQUS were comparable to the previous results of a TOUGH-FLAC simulator. Results from the STOMP-ABAQUS coupled simulator were essentially identical to the fully coupled STOMP hydrogeomechanical simulator when the sequential coupling occurred at small time steps, and deviations between results increased with

  20. Start-up and shutdown thermomechanical transient analyses of the IFMIF European lithium target system

    In the framework of the current IFMIF Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) phase, ENEA is responsible for the design of the European concept of the IFMIF lithium target system which foresees the possibility to periodically replace only the most irradiated and thus critical component (i.e., the backplate) while continuing to operate the rest of the target for a longer period (bayonet backplate concept). With the objective of evaluating the performances of the system in terms of temperature, stress and displacement fields evolution during start-up and shutdown phases, an uncoupled thermomechanical transient analysis has been performed in close collaboration with the University of Palermo by means of a qualified finite element (FE) thermomechanical code. The calculations employed a realistic 3D time-dependent FE model which takes into account all the mechanical and thermal loads including the nuclear heating due to neutron and prompt gamma fields during start-up and decay power of activated products during shutdown. The nuclear data have been calculated by ENEA as part of a parallel extensive neutronic analysis carried out through the MCNP transport code and the EASY-2010 activation code package and then passed as input to the thermomechanical FE model. In this paper, the results of the above transient analyses are reported, highlighting the relevant indications obtained with respect to the fulfillment of the design requirements and possible hints for improving the system design. In particular, it is found that ITER design rules taking into account secondary loads are not always fulfilled during the transient, whereas the predicted displacements allow to exclude any contact of the target system with the surrounding structures

  1. A thermo mechanical benchmark calculation of a hexagonal can in the BTI accident with INCA code

    The thermomechanical 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 INCA code and the results systematically compared with those of ADINA

  2. Thermomechanical behavior of dry contacts in disc brake rotor with a grey cast iron composition

    Belhocine Ali

    2013-01-01

    Full Text Available The main purpose of this study is to analysis the thermomechanical behavior of the dry contact between the brake disc and pads during the braking phase. The simulation strategy is based on the calculation code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

  3. Thermomechanically-controlled Processing for Producing Ship-building Steels

    B. Basu

    2005-01-01

    Full Text Available The thermomechanically-controlled processing of a newly developed high-strength lowalloy steel has been designed in such a way that the problems, normally faced in producing thequench and tempered steels, have been mitigated and the final product (steel plates are available in as rolled condition rather than quench and tempered steels.A low-carbon, low-alloy steel having nickel, chromium, copper, niobium, boron, has been designed for ease of welding, improved weldability over the conventional steels, and responsiveto the thermomechanically-controlled processing. A number of laboratory-scale batches of the alloy were made with different combinations of thermomechanically-controlled processingparameters. The different thermomechanically-controlled processing parameters studied include (i slab-reheating temperature,~ (ii. def.orm ation above recrvstallisation temperature, (iiideformation below recrystallisation temperature, and (iv finish-rolling temperature. The thermomechanically-processed steel plates, under certain combinations of  thermomechanically-controlled ~rocessi-ne.o arameters. showed excellent combination of imvact and tensile n.r on. erties. In this paper, the microstructure-property correlation has been made to throw light on the type of microstructure required to obtain such superior package of mechanical properties. Further, the optimised laboratory-scale thermomechanically-controlled processing parameters, which were used to process newer hatches of the steel made through industrial route, have delivered encouraging results.

  4. Thermo-mechanical ratcheting in jointed rock masses

    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.

  5. Thermomechanic micro-generators for energy harvesting

    Huesgen, Till

    2010-07-01

    This work, in contrast, focuses on the development of a novel thermomechanic generator based on a dynamic micro engine. The engine is fabricated on a chip-scale in silicon technology and is unique regarding its size and properties. A closed engine chamber, filled with a working fluid, performs a reciprocating motion between a heat source and a heat sink. Thereby, the engine operates passively hence it is self starting and the operation frequency depends on the applied temperature difference. Primary goals of this work are the design of the engine and an experimental proof-of-concent. A hybrid model composed of a FEM simulation for the membrane mechanics, analytical calculations of the thermodynamic cycle, and a thermal network model, allows to theoretically investigate the engine performance. The relevant benchmarks are the operation frequency, mechanical output power and the thermal resistance of the engine. Using this model, an exemplary optimization of the engine geometry is conducted with respect to a high efficiency. In this case, a theoretical optimum of 28.3 x 10{sup -4}% is found for the thermomechanic energy conversion. The experimental part focuses on the fabrication and characterization of a not optimized demonstrator engine. Two different types of working fluid are applied, either air or an organic coolant. The maximum measured operation frequency is 1.2 Hz at 100 K temperature difference for the air-filled engine and 0.75 Hy at 37 K temperature difference for the engine filled with the organic coolant. A maximum velocity of 0.061 m/sec and -0.031 m/sec is measured for the upward and downward motion. These experimental data yield a maximum mechanical output power of 0.5 {mu}W for the air-filled engine and 0.26 {mu}W for the engine filled with the organic coolant. The integration of an electric generator provides a further task. Two fundamentally different approaches have been investigated. The first approach is based on an electromagnetic conversion of

  6. Instrumentation requirements for the ESF thermomechanical experiments

    Pott, J. [Sandia National Labs., Albuquerque, NM (United States); Brechtel, C.E. [Agapito (J.F.T.) and Associates, Inc., Grand Junction, CO (United States)

    1992-12-31

    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.

  7. Instrumentation requirements for the ESF thermomechanical experiments

    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

  8. Thermomechanical studies in granite at Stripa, Sweden

    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 10-6/0C at 400C to about 14 x 10-6/0C. 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

  9. Interactive evolution concept for analyzing a rock salt cavern under cyclic thermo-mechanical loading

    König, Diethard; Mahmoudi, Elham; Khaledi, Kavan; von Blumenthal, Achim; Schanz, Tom

    2016-04-01

    The excess electricity produced by renewable energy sources available during off-peak periods of consumption can be used e.g. to produce and compress hydrogen or to compress air. Afterwards the pressurized gas is stored in the rock salt cavities. During this process, thermo-mechanical cyclic loading is applied to the rock salt surrounding the cavern. Compared to the operation of conventional storage caverns in rock salt the frequencies of filling and discharging cycles and therefore the thermo-mechanical loading cycles are much higher, e.g. daily or weekly compared to seasonally or yearly. The stress strain behavior of rock salt as well as the deformation behavior and the stability of caverns in rock salt under such loading conditions are unknown. To overcome this, existing experimental studies have to be supplemented by exploring the behavior of rock salt under combined thermo-mechanical cyclic loading. Existing constitutive relations have to be extended to cover degradation of rock salt under thermo-mechanical cyclic loading. At least the complex system of a cavern in rock salt under these loading conditions has to be analyzed by numerical modeling taking into account the uncertainties due to limited access in large depth to investigate material composition and properties. An interactive evolution concept is presented to link the different components of such a study - experimental modeling, constitutive modeling and numerical modeling. A triaxial experimental setup is designed to characterize the cyclic thermo-mechanical behavior of rock salt. The imposed boundary conditions in the experimental setup are assumed to be similar to the stress state obtained from a full-scale numerical simulation. The computational model relies primarily on the governing constitutive model for predicting the behavior of rock salt cavity. Hence, a sophisticated elasto-viscoplastic creep constitutive model is developed to take into account the dilatancy and damage progress, as well as

  10. EXPERIENCE WITH THERMOMECHANICAL FATIGUE UNDER SERVICE-TYPE LOADING

    A.Scholz; A.Schmidt; A.Samir; C.Berger

    2004-01-01

    The thermomechanical fatigue behaviour of different high temperature alloys has been investigated and is under investigation respectively. The creep-fatigue behaviour of heat resistant steels was investigated by long-term service-type strain cycling tests simulating thermomechanical fatigue (TMF-) loading conditions at the heated surface of e.g. turbine rotors. Single-stage as well as three-stage cycles leads to similar results at the application of the damage accumulation rule. Life prediction which simulates typical combinations of cold starts, warm starts and hot starts has been established successfully for isothermal service-type loading and will be exceeded for thermomechanical loading. Long-term thermomechanical fatigue testing of Thermal Barrier Coating systems show typical delamination damage. An advanced TMF cruciform testing system enables complex multiaxial loading.

  11. Thermo-mechanical analysis of an SI engine piston using different boundary condition treatments

    Amir-Hasan Kakaee; Javad Gharloghi; Aliasghar Foroughifar; Abdoreza Khanlari

    2015-01-01

    Heat transfer of an SI engine’s piston is calculated by employing three different methods based on resistor-capacitor model with the help of MATLAB code, and then the piston is thermo-mechanically analyzed using commercial ANSYS code. The results of three methods are compared to study their effects on the piston thermal behavior. It is shown that resistor−capacitor model with less number of equations and consequently less solution time, is an appropriate method for solving problems of engine piston heat transfer. In the second part, the thermal stresses due to non-uniform temperature distribution, and mechanical stresses due to mechanical loads are calculated. Finally, the temperature distributions as a thermal load along with mechanical loads are applied to the piston to determine the total stress distribution and critical fracture zones. It is found that the amount of thermal stresses is considerable.

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

    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.)

  13. Safety assessment of nuclear power plant pipelines against thermo-mechanical fatigue in the presence of hybrid uncertainties

    Power plant piping components are subjected to a variety of thermal and thermo-mechanical loads, which include loads during hot shut down and cold shut down, in addition to the normal or steady operating loads of the power plant. A large number of piping failures in Pressurized Heavy Water reactors in the form of cracks and leaks due to these thermo-mechanical loads have been reported. Thermomechanical fatigue is one of the primary life-limiting factors for piping components in high temperature applications. In this paper, a procedure for the safety assessment of a nuclear power plant piping component against thermomechanical fatigue, by treating the relevant uncertain variables as random or fuzzy depending upon the source of uncertainty, is proposed. The fuzzy failure probabilities are computed using the method developed at CSIR-SERC, combining the vertex method with Monte Carlo simulation technique. The strain-based approach, which is the general approach employed for continuum response in safe-life, finite-life region i.e., the low cycle fatigue region with stabilized cyclic stress-strain constants, is used in the safety assessment. An example of a main steam piping of an operating thermal power plant is considered for illustrating the safety assessment procedure. It is also noted that one can determine the bounds for failure probability from the resulting fuzzy set for failure probability with minimal computational effort. The proposed procedure will help in rationally taking into account various uncertainties while designing the components with known/acceptable levels of safety specified either in codes or by learned bodies (AERB codes/NUREG). (author)

  14. Thermo-mechanical characterization of silicone foams

    Rangaswamy, Partha [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Smith, Nickolaus A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cady, Carl M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lewis, Matthew W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-01

    Cellular solids such as elastomeric foams are used in many structural applications to absorb and dissipate energy, due to their light weight (low density) and high energy absorption capability. In this paper we will discuss foams derived from S5370, a silicone foam formulation developed by Dow Corning. In the application presented, the foam is consolidated into a cushion component of constant thickness but variable density. A mechanical material model developed by Lewis (2013), predicts material response, in part, as a function of relative density. To determine the required parameters for this model we have obtained the mechanical response in compression for ambient, cold and hot temperatures. The variable density cushion provided samples sufficient samples so that the effect of sample initial density on the mechanical response could be studied. The mechanical response data showed extreme sensitivity to relative density. We also observed at strains corresponding to 1 MPa a linear relationship between strain and initial density for all temperatures. Samples taken from parts with a history of thermal cycling demonstrated a stiffening response that was a function of temperature, with the trend of more stiffness as temperature increased above ambient. This observation is in agreement with the entropic effects on the thermo-mechanical behavior of silicone polymers. In this study, we present the experimental methods necessary for the development of a material model, the testing protocol, analysis of test data, and a discussion of load (stress) and gap (strain) as a function of sample initial densities and temperatures

  15. Thermomechanical fatigue in single crystal superalloys

    Moverare Johan J.

    2014-01-01

    Full Text Available Thermomechanical fatigue (TMF is a mechanism of deformation which is growing in importance due to the efficiency of modern cooling systems and the manner in which turbines and associated turbomachinery are now being operated. Unfortunately, at the present time, relatively little research has been carried out particularly on TMF of single crystal (SX superalloys, probably because the testing is significantly more challenging than the more standard creep and low cycle fatigue (LCF cases; the scarcity and relative expense of the material are additional factors. In this paper, the authors summarise their experiences on the TMF testing of SX superalloys, built up over several years. Emphasis is placed upon describing: (i the nature of the testing method, the challenges involved in ensuring that an given testing methodology is representative of engine conditions (ii the behaviour of a typical Re-containing second generation alloy such as CMSX-4, and its differing performance in out-of-phase/in-phase loading and crystallographic orientation and (iii the differences in behaviour displayed by the Re-containing alloys and new Re-free variants such as STAL15. It is demonstrated that the Re-containing superalloys are prone to different degradation mechanisms involving for example microtwinning, TCP precipitation and recrystallisation. The performance of STAL15 is not too inferior to alloys such as CMSX-4, suggesting that creep resistance itself does not correlate strongly with resistance to TMF. The implications for alloy design efforts are discussed.

  16. Thermomechanical evaluation of BWR fuel elements for procedures of preconditioned with FEMAXI-V

    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)

  17. 3-D Numerical Simulation and Analysis of Complex Fiber Geometry RaFC Materials with High Volume Fraction and High Aspect Ratio based on ABAQUS PYTHON

    Jin, BoCheng

    2011-12-01

    Organic and inorganic fiber reinforced composites with innumerable fiber orientation distributions and fiber geometries are abundantly available in several natural and synthetic structures. Inorganic glass fiber composites have been introduced to numerous applications due to their economical fabrication and tailored structural properties. Numerical characterization of such composite material systems is necessitated due to their intrinsic statistical nature, which renders extensive experimentation prohibitively time consuming and costly. To predict various mechanical behavior and characterizations of Uni-Directional Fiber Composites (UDFC) and Random Fiber Composites (RaFC), we numerically developed Representative Volume Elements (RVE) with high accuracy and efficiency and with complex fiber geometric representations encountered in uni-directional and random fiber networks. In this thesis, the numerical simulations of unidirectional RaFC fiber strand RVE models (VF>70%) are first presented by programming in ABAQUS PYTHON. Secondly, when the cross sectional aspect ratios (AR) of the second phase fiber inclusions are not necessarily one, various types of RVE models with different cross sectional shape fibers are simulated and discussed. A modified random sequential absorption algorithm is applied to enhance the volume fraction number (VF) of the RVE, which the mechanical properties represents the composite material. Thirdly, based on a Spatial Segment Shortest Distance (SSSD) algorithm, a 3-Dimentional RaFC material RVE model is simulated in ABAQUS PYTHON with randomly oriented and distributed straight fibers of high fiber aspect ratio (AR=100:1) and volume fraction (VF=31.8%). Fourthly, the piecewise multi-segments fiber geometry is obtained in MATLAB environment by a modified SSSD algorithm. Finally, numerical methods including the polynomial curve fitting and piecewise quadratic and cubic B-spline interpolation are applied to optimize the RaFC fiber geometries

  18. FY15 Report on Thermomechanical Testing

    Hansen, Francis D. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Buchholz, Stuart [RESPEC, Rapid City, SD (United States)

    2015-08-01

    Sandia is participating in the third phase of a United States (US)-German Joint Project that compares constitutive models and simulation procedures on the basis of model calculations of the thermomechanical behavior and healing of rock salt (Salzer et al. 2015). The first goal of the project is to evaluate the ability of numerical modeling tools to correctly describe the relevant deformation phenomena in rock salt under various influences. Among the numerical modeling tools required to address this are constitutive models that are used in computer simulations for the description of the thermal, mechanical, and hydraulic behavior of the host rock under various influences and for the long-term prediction of this behavior. Achieving this goal will lead to increased confidence in the results of numerical simulations related to the secure disposal of radioactive wastes in rock salt. Results of the Joint Project may ultimately be used to make various assertions regarding stability analysis of an underground repository in salt during the operating phase as well as long-term integrity of the geological barrier in the post-operating phase A primary evaluation of constitutive model capabilities comes by way of predicting large-scale field tests. The Joint Project partners decided to model Waste Isolation Pilot Plant (WIPP) Rooms B & D which are full-scale rooms having the same dimensions. Room D deformed under natural, ambient conditions while Room B was thermally driven by an array of waste-simulating heaters (Munson et al. 1988; 1990). Existing laboratory test data for WIPP salt were carefully scrutinized and the partners decided that additional testing would be needed to help evaluate advanced features of the constitutive models. The German partners performed over 140 laboratory tests on WIPP salt at no charge to the US Department of Energy (DOE).

  19. Parametric study of thermo-mechanical behaviour of 19-element PHWR fuel bundle having AHWR fuel material

    AHWR Th-LEU of 4.3 weight % 235U enrichment is a fuel design option for its trial irradiation in Indian PHWRs. The important component of this option is the large enhancement in the average discharge burn-up from the core. A parametric study of the 19-element fuel bundle, with natural uranium currently is being used in all operating 220 MWe PHWRs, has been carried out for AHWR Th-LEU fuel material by computer code FUDA MOD2. The important fuel parameters such as fuel temperature, fission gas release, fuel swelling and sheath strain have been analyzed for required fuel performance. With Th-LEU, average discharge burnups of about 25,000 MW-d/TeHE can be achieved. The FUDA code (Fuel Design Analysis code) MOD2 version has been used in the fuel element analysis. The code takes into account the inter-dependence of different parameters like fuel pellet temperatures, pellet expansions, fuel-sheath gap heat transfer, sheath strain and stresses, fission gas release and gas pressures, fuel densification etc. Thermo-mechanical analysis of fuel element having AHWR material is carried out for the bundle power histories reaching up to design burn-up 40000 MWd/TeHE. The resultant parameters such as fuel temperature, sheath plastic strain and fission gas pressure for AHWR fuel element were compared with respective thermo-mechanical parameters for similar fuel bundle element with natural uranium as fuel material. (author)

  20. Study of the damaging mechanisms of a carbon - carbon composite bonded to copper under thermomechanical loading

    The purpose of this work is to understand and to identify the damaging mechanisms of Carbon-Carbon composite bonded to copper under thermomechanical loading. The study of the composite allowed the development of non-linear models. These ones have been introduced in the finite elements analysis code named CASTEM 2000. They have been validated according to a correlation between simulation and mechanical tests on multi-material samples. These tests have also permitted us to better understand the behaviour of the bonding between composite and copper (damaging and fracture modes for different temperatures) under shear and tensile loadings. The damaging mechanisms of the bond under thermomechanical loading have been studied and identified according to microscopic observations on mock-ups which have sustained thermal cycling tests: some cracks appear in the composite, near the bond between the composite and the copper. The correlation between numerical and experimental results have been improved because of the reliability of the composite modelization, the use of residual stresses and the results of the bond mechanical characterisation. (author)

  1. Study of the damaging mechanisms of a copper / carbon - carbon composite under thermomechanical loading

    The purpose of this work is to understand and to identify the damaging mechanisms of Carbon-Carbon composite bonded to copper under thermomechanical loading. The study of the composite allowed the development of non-linear models. These ones have been introduced in the finite elements analysis code named CASTEM2000. They have been validated according to a correlation between simulation and mechanical tests on multi-material samples. These tests have also permitted us to better understand the behaviour of the bonding between composite and copper (damaging and fracture modes for different temperatures) under shear and tensile loadings. The damaging mechanisms of the bond under thermomechanical loading have been studied and identified according to microscopic observations on mock-ups which have sustained thermal cycling tests: some cracks appear in the composite, near the bond between the composite and the copper. The correlation between numerical and experimental results have been improved because of the reliability of the composite modelization, the use of residual stresses and the results of the bond mechanical characterization. (author)

  2. Based on ABAQUS In-situ stress Balance of Geotechnical Engineering%基于ABAQUS岩土工程中地应力平衡的探讨

    马云峰

    2014-01-01

    平衡地应力是岩土工程计算分析中十分重要的部分,在岩土施工前保证地表位移近似为零,是数值模拟的首要前提。利用 ABAQUS 对某基坑开挖前的土体进行地应力平衡,根据现场土体的物理性质指标,将地应力平衡前后土体的应力和位移进行对比。进行地应力平衡后土体的位移数量级小于10-6,并且任意深度的竖向应力值等于该处深度与土体密度的乘积。%Balance in-situ stress is very important part in geotechnical engineering calculation, in front of the geotechnical construction guarantee approximation of surface displacement is zero, is the first premise of numerical simulation. Using ABAQUS to some soil excavation in front of the in-situ stress balance, according to the field of soil physical property indexes, the in-situ stress balance of stress and displacement of soil before and after comparison. In-situ stress balance of soil displacement of orders of magnitude less than 10-6, and the depth of the vertical stress value equal to the depth and the product of the density of soil.

  3. The Damage Law of HTPB Propellant under Thermomechanical Loading

    Liu, Cheng-wu; Yang, Jian-hong; Wang, Xian-meng; Ma, Yong-kang

    2016-01-01

    By way of measuring the acoustic emission (AE) signals of Hydroxyl-terminated polybutadiene (HTPB) propellant in condition of uniform speed, and combined with the scanning electron microscopy (SEM) fracture surface observation, the damage law of HTPB composite solid propellant under thermomechanical loading was studied. The results show that the effects of thermomechanical loading on HTPB propellant are related to the time and can be divided into three different stages. In the first stage, thermal air aging dominates; in the second stage, interface damage is dominant; and in the third stage, thermal air aging is once again dominant.

  4. Computer codes for the analysis of flask impact problems

    This review identifies typical features of the design of transportation flasks and considers some of the analytical tools required for the analysis of impact events. Because of the complexity of the physical problem, it is unlikely that a single code will adequately deal with all the aspects of the impact incident. Candidate codes are identified on the basis of current understanding of their strengths and limitations. It is concluded that the HONDO-II, DYNA3D AND ABAQUS codes which ar already mounted on UKAEA computers will be suitable tools for use in the analysis of experiments conducted in the proposed AEEW programme and of general flask impact problems. Initial attention should be directed at the DYNA3D and ABAQUS codes with HONDO-II being reserved for situations where the three-dimensional elements of DYNA3D may provide uneconomic simulations in planar or axisymmetric geometries. Attention is drawn to the importance of access to suitable mesh generators to create the nodal coordinate and element topology data required by these structural analysis codes. (author)

  5. Precision Glass Molding: Validation of an FE Model for Thermo-Mechanical Simulation

    Sarhadi, Ali; Hattel, Jesper Henri; Hansen, Hans Nørgaard

    2014-01-01

    glass molding process including heating, pressing, and cooling stages. Temperature- dependent viscoelastic and structural relaxation behavior of the glass material are implemented through a FORTRAN material subroutine (UMAT) into the commercial FEM program ABAQUS, and the FE model is validated...

  6. Simulation of the irradiation-induced thermo-mechanical behaviors evolution in monolithic U–Mo/Zr fuel plates under a heterogeneous irradiation condition

    Highlights: • The three-dimensional stress update algorithms in a co-rotational framework are developed for U–Mo and Zircalloy with the irradiation effects. • An effective method for three-dimensional modeling of the in-pile behaviors in heterogeneously irradiated monolithic fuel plates is established and validated. • The effects of the fission-induced creep effects in the U–Mo foil are investigated in detail. • A deformation phenomenon similar to the irradiation experimental results is obtained. - Abstract: For monolithic fuel plates with U–Mo foil and Zircalloy cladding, the three-dimensional large deformation incremental constitutive relations and stress update algorithms in the co-rotational coordinate framework are developed for the fuel and cladding with their respective irradiation effects involved. Three-dimensional finite element simulation of their in-pile thermo-mechanical coupling behaviors under a location-dependent irradiation condition is implemented via the validated user-defined subroutines UMATHT and UMAT in ABAQUS. Comparison of the simulation results for two cases with or without creep considered in the U–Mo foil indicates that with the irradiation creep included (1) considerable stress-relaxation appears in the U–Mo foil, and the mechanical interaction between fuel and cladding is weakened; (2) approximately identical thickness increments in the plate and fuel foil exist and become comparably larger; (3) plastic deformation in the cladding is significantly diminished

  7. Thermomechanical loading applied on the cladding tube during the pellet cladding mechanical interaction phase of a rapid reactivity initiated accident

    Hellouin de Menibus, Arthur, E-mail: arthur.hellouin-de-menibus@cea.fr [CEA Saclay/DEN/DANS/DMN/SRMA, 91191 Gif-sur-Yvette (France); Sercombe, Jerome [CEA Cadarache/DEN/CAD/DEC/SESC, 13108 St Paul lez Durance (France); Auzoux, Quentin; Poussard, Christophe [CEA Saclay/DEN/DANS/DMN/SEMI, 91191 Gif-sur-Yvette (France)

    2014-10-15

    Calculations of the CABRI REP-Na5 pulse were performed with the ALCYONE code in order to determine the evolution of the thermomechanical loading applied on the cladding tube during the Pellet–Cladding Mechanical Interaction (PCMI) phase of a rapid Reactivity Initiated Accident (RIA) initiated at 280 °C that lasted 8.8 ms. The evolution of the following parameters are reported: the cladding temperature, heating rate, strain rate and loading biaxiality. The impact of these parameters on the cladding mechanical behavior and fracture are then briefly reviewed.

  8. Thermo-mechanical Analysis of the CLIC Post-Linac Energy Collimators

    Resta-Lopez, J; Latina, A

    2012-01-01

    The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed for passive protection of the Beam Delivery System (BDS) against miss-steered beams due to failure modes in the main linac. In this paper, a thermo-mechanical analysis of the CLIC energy collimators is presented. This study is based on simulations using the codes FLUKA and ANSYS when an entire bunch train hits the collimators. Different failure mode scenarios in the main linac are considered. The aim is to improve the collimator in order to make a reliable and robust design so that survives without damage the impact of a full bunch train in case of likely events generating energy errors.

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

    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

  10. A program to validate computer codes for container impact analysis

    The detailed analysis of containers during impacts to assess either margins to failure or the consequences of different design strategies, requires the use of sophisticated computer codes to model the interactions of the various structural components. The combination of plastic deformation, impact and sliding at interfaces and dynamic loading effects provides a severe test of both the skill of the analyst and the robustness of the computer codes. A program of experiments has been under way at Winfrith since 1987 using extensively instrumented models to provide data for the validation of such codes. Three finite element codes, DYNA3D, HONDO-II and ABAQUS, were selected as suitable tools to cover the range of conditions expected in typical impacts. The impact orientation, velocity and instrumentation locations for the experiments are specified by pre-test calculations using these codes. Post-test analyses using the actual impact orientation and velocities are carried out as necessary if significant discrepancies are found

  11. A piezo-thermal probe for thermomechanical analysis

    Gaitas, A.; Gianchandani, S.; Zhu, W.

    2011-01-01

    Thermomechanical analysis (TMA) is widely used to characterize materials and determine transition temperatures and thermal expansion coefficients. Atomic-force microscopy (AFM) microcantilevers have been used for TMA. We have developed a micromachined probe that includes two embedded sensors: one fo

  12. THERMO-MECHANICALLY PROCESSED ROLLED WIRE FOR HIGH

    V. A. Lutsenko

    2015-06-01

    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.

  13. Stress wave propagation in the Institute of Thermomechanics

    Okrouhlík, Miloslav

    Prague : ITAM AS CR, v. v. i., 2012 - (Náprstek, J.; Fischer, C.), s. 969-970 ISBN 978-80-86246-40-6. [Engineering Mechanics 2012 /18./. Svratka (CZ), 14.05.2012-17.05.2012] Institutional research plan: CEZ:AV0Z20760514 Keywords : historical survey * stress wave propagation in solids * Institute of Thermomechanics Subject RIV: BI - Acoustics

  14. On the simulation of thermo-mechanical forming processes

    Huetink, J.

    1986-01-01

    A formulation for elastic-plastic constitutive equations is given based on principles of continuum thermo-mechanics and thermodynamics. Energy dissipation and phase changes are included in the mathematical model. It is shown that kinematic hardening can be described properly for large deformations,

  15. Thermomechanical fatigue and damage mechanisms in Sanicro 25 steel

    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 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: 2.567, year: 2014

  16. Strengthening of Aluminum Alloy 2219 by Thermo-mechanical Treatment

    Li, Xifeng; Lei, Kun; Song, Peng; Liu, Xinqin; Zhang, Fei; Li, Jianfei; Chen, Jun

    2015-10-01

    Strengthening of aluminum alloy 2219 by thermo-mechanical treatment has been compared with artificial aging. Three simple deformation modes including pre-stretching, compression, and rolling have been used in thermo-mechanical treatment. The tensile strength, elongation, fracture feature, and precipitated phase have been investigated. The results show that the strengthening effect of thermo-mechanical treatment is better than the one of artificial aging. Especially, the yield strength significantly increases with a small decrease of elongation. When the specimen is pre-stretched to 8.0%, the yield strength reaches 385.0 MPa and increases by 22.2% in comparison to the one obtained in aging condition. The maximum tensile strength of 472.4 MPa is achieved with 4.0% thickness reduction by compression. The fracture morphology reveals locally ductile and brittle failure mechanism, while the coarse second-phase particles distribute on the fracture surface. The intermediate phases θ″ or θ' orthogonally precipitate in the matrix after thermo-mechanical treatment. As compared to artificial aging, the cold plastic deformation increases distribution homogeneity and the volume fraction of θ'' or θ' precipitates. These result in a better strengthening effect.

  17. Obtaining a TRIP microstructure by thermomechanical treatment without isothermal holding

    Masek, B.; Jirkova, H.; Kucerova, L.; F-X Wagner, M.

    2016-03-01

    The contemporary development of technological processes for the production of modern multiphase steels can be characterized by the need for precise control of their technological parameters. The design of modern technological processes that allow sophisticated microstructures to be obtained usually cannot be carried out on real production equipment for technical as well as economical reasons. Therefore, new processes and test devices are continuously being developed to make it possible to simulate and model thermomechanical treatments on small specimens with precise control and monitoring of process parameters. A simulator for experimental modelling of thermomechanical processes has been developed at the University of West Bohemia. In this paper, to demonstrate the feasibility of simulating thermomechanical treatments with this setup on a lab scale, we discuss the thermomechanical treatment of TRIP steels without isothermal holding - a processing route that is difficult to handle and thus poses several technological as well as economic problems. The realistic processing of wire rolling with different cooling strategies is tested on the TRIP CMnSiNb steel. Our results show that the processing route without isothermal holding allows to obtain multiphase microstructures with a tensile strength of up to 835 MPa and a ductility A5mm = 25%.

  18. Performance analysis of VVER-type fuel rods with the STOFFEL-1 computer code

    The main features of the fuel rod performance modelling computer code STOFFEL-1 are described. Submodels of the code are briefly characterized, and some results of comparisons between model predictions and experiments are presented. Examples of modelling calculations are given for some thermo-mechanical values of VVER-1000 fuel rods. (author)

  19. 基于ABAQUS的列车盘型制动的温度场分析%Analysis on Temperature Field of Train Disc Brake Based on ABAQUS

    王国顺

    2013-01-01

    The influences of rotating speed and the friction radius,height and shape,and place form of braking block on the temperature field of the brake disc and brake block were simulated by the finite element analysis software of ABAQUS.The results show that with the increase of crank's rotating speed,the brake disc and brake block's temperatures are increased,and the distribution of high temperature region is changed from stripe to speckle.The reason is that with the increase of revolving speed,the vibration between the friction pairs is aggravated,and the local contact was produced to cause the high temperature.There is an inflection point of temperature in the thickness direction of brake disc,with the increase of the distance to the friction surface,the temperature is declined rapidly,and in the distance of 3 ~ 6 mm to the friction surface,the change of temperature is not obvious.The change of brake block height or shape has no obvious influence on the brake disc temperature,while the placement form of the triangle brake block has influence on temperature distribution.%应用有限元软件ABAQUS,模拟转动速度和制动块摩擦半径、高度以及形状与放置形式等对制动盘和制动块温度场的影响.得出如下结论:随转速的提高,制动盘和制动块温度升高,高温区的分布由条带状向斑点状转变,原因在于随转速增加,摩擦副间的振动程度加剧,从而造成局部接触产生高温.制动盘温度在厚度方向上存在一个拐点,随深度增加,制动盘温度快速下降,在距摩擦表面3~6mm时,温度变化不明显.制动块高度、形状改变,对制动盘温度无明显影响,而三角形制动块的放置形式对制动块温度分布有影响.

  20. Thermomechanical behavior of Mexican fabricated fuel

    The Fuel Fabrication Pilot Plant of the Instituto Nacional de Investigaciones Nucleares (ININ-National Institute of Nuclear Research supplied four fuel assemblies of the GE9B type for the Laguna Verde Nuclear Power Plant (LVNPP). The Institute carried out the ceramic and fuel rod fabrication and assembled the fuel bundles, using General Electric Nuclear Energy (GENE) materials. This company licensed the Mexican Nuclear Research Institute as fuel supplier for the LVNPP, provided technical support, and issued the nuclear and mechanical fuel performance guarantees for the ININ fuel. Irradiation was carried out at Unit 1 of LVNPP and fuel burnup was calculated with the HELIOS-CM-PRESTO system. Post-irradiation examination of the Institute fuel was not performed because of the high costs involved. However, the exhaustive Q.C. carried out during fabrication permitted the use of real values for many fabrication parameters. A computational code is currently being developed for evaluating the neutronic, thermal and mechanical performance of a fuel element under several different operation conditions. This code has been benchmarked with against data from the LVNPP. (authors)

  1. A holistic approach to thermomechanical processing of alloys

    S Venugopal; Baldev Raj

    2003-06-01

    New process design and control methods are needed for significantly improving productivity and reducing costs of thermomechanical processes such as hot metal forging. Current practices for accomplishing basic design tasks such as selecting the number of forming steps and specifying the processing conditions for each thermomechanical operation produce feasible solutions that are often far from optimal. Substantial improvements in effectiveness and efficiency can be realized through holistic approaches that optimize the whole system performance and not just individual subsystems such as workpiece material behavior, material flow in dies, and equipment responses. Recent progress in the application of dynamical modelling and process design techniques using ideal forming concepts and trajectory optimization are discussed. Monitoring methods for the on-line monitoring of the process and an intelligent forging system has been proposed.

  2. Hydrogen embrittlement of thermomechanically treated 18Ni Maraging steel

    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. Thermomechanics analysis and optimization for high power density blanket

    Thermomechanics analysis, i.e. steady thermal analysis and steady thermal stress analysis have been carried out for a high power density blanket. The Fusion Experimental Breeder (FEB) is adopted as the reference reactor. The parts for the blanket module in Pro/ENGINEER were created, then turn to Pro/MECHANICA functionality for thermomechanics analysis. During analysis, the distribution of the power density in the blanket was optimized to be more flat, the arched curvature and rounds of the cooling tube panels were optimized to less stiffness, and the boundary condition at the interface of helium cooling tube panel and manifold chamber was optimized, which is reasonable by using advanced welding processes with electron beam or laser beam in a single pass. To the end, a maximum temperature Tm 350 degree C and a maximum shear stress τm 80 MPa for the helium cooling panels have been shown in the calculations. (authors)

  4. Thermomechanical Behavior of High Performance Epoxy/Organoclay Nanocomposites

    Artur Soares Cavalcanti Leal; Carlos Jose de Araújo; Antônio Gilson de Barbosa Lima; Suédina Maria Lima Silva

    2014-01-01

    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 nanocompo...

  5. Progress in thermomechanical control of steel plates and their commercialization

    Kiyoshi Nishioka and Kazutoshi Ichikawa

    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, distortio...

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

    Carlos Carvalho Engler-Pinto Júnior; Dirceu Spinelli

    2014-01-01

    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 ...

  7. Thermomechanical process intensification for oil extraction from orange peels.

    Rezzoug, Sid-Ahmed; Louka, Nicolas

    2009-01-01

    The study investigated the intensification and improvement of oil extraction from orange peel through a thermomechanical process: the Instantaneous Controlled Pressure Drop (briefly D.I.C process). This process involves subjecting orange peel for a short time to steam pressure, followed by an instantaneous decompression to vacuum at 50 mbar. Central composite design was used to study the combined effects of processing steam pressure (1–7 bar; which corresponds to a temperature ranging between...

  8. Thermo-mechanical behaviour of a compacted swelling clay

    TANG, Anh Minh; Cui, Yu-Jun; Barnel, Nathalie

    2008-01-01

    International audience Compacted unsaturated swelling clay is often considered as a possible buffer material for deep nuclear waste disposal. An isotropic cell permitting simultaneous control of suction, temperature and pressure was used to study the thermo-mechanical behaviour of this clay. Tests were performed at total suctions ranging from 9 to 110 MPa, temperature from 25 to 80 °C, isotropic pressure from 0.1 to 60 MPa. It was observed that heating at constant suction and pressure indu...

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

    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.

  10. A thermomechanical pretreatment to improve enzymatic hydrolysis of wheat straw

    Maache-Rezzoug, Zoulikha; Maugard, Thierry; Nouviaire, Armelle; Goude, Romain; Geoffroy, Stanley; Rezzoug, Sid-Ahmed

    2009-01-01

    International audience Wheat straw was pretreated with a thermomechanical process developed in our laboratory to increase the enzymatic hydrolysis extent of potentially fermentable sugars. This process involves subjecting the lignocellulosic biomass for a short time to saturated steam pressure, followed by an instantaneous decompression to vacuum at 50 mbar. Increasing of the heat induced by the saturated steam result in intensive vapour formation in the capillary porous structure of the p...

  11. Thermo-mechanical properties of compressed rubber block

    Pešek, Luděk; Půst, Ladislav; Šulc, Petr

    Besancon: Comité Francais pour la Promotion de la Science des Mécanismes et des Machines, 2007 - (Merlet, J.; Dahan, M.), s. 868-873 [IFToMM 2007 /12./. Besancon (FR), 17.06.2007-21.06.2007] R&D Projects: GA ČR GA101/05/2669 Institutional research plan: CEZ:AV0Z20760514 Keywords : vibrodamping elements * thermo-mechanic interaction * rubber Subject RIV: BI - Acoustics

  12. Finite elements for the thermomechanical calculation of massive structures

    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.)

  13. Fuel performance analysis code 'FAIR'

    For modelling nuclear reactor fuel rod behaviour of water cooled reactors under severe power maneuvering and high burnups, a mechanistic fuel performance analysis code FAIR has been developed. The code incorporates finite element based thermomechanical module, physically based fission gas release module and relevant models for modelling fuel related phenomena, such as, pellet cracking, densification and swelling, radial flux redistribution across the pellet due to the build up of plutonium near the pellet surface, pellet clad mechanical interaction/stress corrosion cracking (PCMI/SSC) failure of sheath etc. The code follows the established principles of fuel rod analysis programmes, such as coupling of thermal and mechanical solutions along with the fission gas release calculations, analysing different axial segments of fuel rod simultaneously, providing means for performing local analysis such as clad ridging analysis etc. The modular nature of the code offers flexibility in affecting modifications easily to the code for modelling MOX fuels and thorium based fuels. For performing analysis of fuel rods subjected to very long power histories within a reasonable amount of time, the code has been parallelised and is commissioned on the ANUPAM parallel processing system developed at Bhabha Atomic Research Centre (BARC). (author). 37 refs

  14. A finite element model for thermomechanical analysis in casting processes

    This paper summarizes the recent work of the authors in the numerical simulation of casting processes. In particular, a coupled thermomechanical model to simulate the solidification problem in casting has been developed. The model, based on a general isotropic thermoelasto-plasticity theory and formulated in a macroscopical point of view, includes generalized phase-change effects and considers the different thermomechanical behaviour of the solidifying material during its evolution from liquid to solid. For this purpose, a phase-change variable, plastic evolution equations and a temperature-dependent material constitutive law have been defined. Some relevant aspects of this model are presented here. Full thermomechanical coupling terms have been considered as well as variable thermal and mechanical boundary conditions: the first are due to air gap formation, while the second involve a contact formulation. Particular details concerning the numerical implementation of this model are also mentioned. An enhanced staggered scheme, used to solve the highly non-linear fully coupled finite element equations, is proposed. Furthermore, a proper convergence criterion to stop the iteration process is adopted and, although the quadratic convergence of Newton-Rapshon's method is not achieved, several numerical experiments demonstrate reasonable convergence rates. Finally, an experimental cylindrical casting test problem, including phase-change phenomena, temperature-dependent constitutive properties and contact effects, is analyzed. Numerical results are compared with some laboratory measurements. (orig.)

  15. Modelling of WWER fuel rod during LOCA conditions using FEM code ANSYS

    The report presents the results of the computer simulation of the IFA-650.6 experiment, the sixth test in Halden LOCA test project series, performed in May 18, 2007 with a pre-irradiated WWER-440 fuel with maximum burnup of 56 MWd/kgU. The thermo-mechanical analysis was fulfilled with the license finite element ANSYS code package.The calculation was carried out with the 2D axisymmetric and 3D problem definitions. Analysis of the calculational results shows that the ANSYS code can adequately simulate thermo-mechanical behavior of cladding under IFA-650.6 test conditions. (authors)

  16. Free Vibration Analysis for Layered Shells Accounting of Variable Kinematic and Thermo-Mechanical Coupling

    S. Brischetto; Carrera, E.

    2012-01-01

    The free vibration analysis of one-layered and two-layered metallic cylindrical shell panels is evaluated in this work. The free frequency values are investigated for both thermo-mechanical and pure mechanical problems. Thermo-mechanical frequencies are calculated by means of a fully coupled thermo-mechanical model where both the displacement and temperature are primary variables in the considered governing equations. Pure mechanical frequencies are obtained from a mechanical model where the ...

  17. Clinical coding. Code breakers.

    Mathieson, Steve

    2005-02-24

    --The advent of payment by results has seen the role of the clinical coder pushed to the fore in England. --Examinations for a clinical coding qualification began in 1999. In 2004, approximately 200 people took the qualification. --Trusts are attracting people to the role by offering training from scratch or through modern apprenticeships. PMID:15768716

  18. Neutronic and thermo-mechanic calculations for the design of the TRADE spallation target

    The spallation target of the TRADE Project-at present in stand-by waiting for further decisions on budget availability-is based on the concept of a solid target cooled by forced convection. The solid target approach presents a maximum power density limitation due to the high thermal stresses which are generated by the huge differential temperatures in the material. These at their turn stem from the proton energy loss in the volume of the target material and the water cooling on the external surface. The maximum operating beam power and the proton beam profile were imposed by experimental and geometrical considerations; the peak power density of the target material (Tantalum) turned out to be about 8E09 W/m3. The power generation of the reference configuration of the spallation target was accurately calculated by the code MCNPX, which allows to simulate individual particle tracks in 3-D geometry, starting from the accelerated 140 MeV protons down to all the relevant secondary particles. The temperature distribution and the stress and strain maps were calculated by the thermo-mechanical ANSYS code. The main calculation results are reported. The elastic-plastic analysis of the target material is performed in terms of maximum allowable deformation, fatigue and progressive plastic deformation

  19. Transient Thermo-Mechanical Analysis of the TPSG4 Beam Diluter

    Goddard, B; Herrera-Martínez, A; Kadi, Y; Marque, S

    2002-01-01

    A new extraction channel is being built in the Super Proton Synchrotron (SPS) Long Straight Section 4 (LSS4) to transfer proton beams to the Large Hadron Collider (LHC) and also to the CERN Neutrino to Gran Sasso (CNGS) target. The beam is extracted in a fast mode during a single turn. For this purpose a protection of the MSE copper septum coil, in the form of a beam diluting element placed upstream, will be required to cope with the new failure modes associated with the fast extraction operation. The present analysis focuses on the thermo-mechanical behavior of the proposed TPSG4 diluter element irradiated by a fast extracted beam (up to 4.9 x 10^13 protons per 7.2 mus pulse) from the SPS. The deposited energy densities, estimated from primary and secondary particle simulations using the high-energy particle transport code FLUKA, were converted to internal heat generation rates taken as a thermal load input for the finite-element engineering analyses code ANSYS. According to the time dependence of the extrac...

  20. DART-TM: A thermomechanical version of DART for LEU VHD dispersed and monolithic fuel analysis

    A collaboration agreement between ANL/USDOE 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 thermal FASTDART version was developed that includes mechanistic models for the calculation of the fission-gas-bubble and fuel particle size distribution, reaction layer thickness, and meat thermal conductivity. FASTDART was presented at the last RERTR Meeting that included validation against RERTR 3 irradiation data. The thermal FASTDART version was assessed as an adequate tool for modeling the behavior of LEU U-Mo dispersed fuels under irradiation against PIE RERTR irradiation data. During this past year the development of a 3-D thermo-mechanical version of the code for modeling the irradiation behavior of LEU U-Mo monolithic and dispersion fuel was initiated. Some preliminary results of this work will be shown during RERTR-2003 meeting. (author)

  1. Permutation codes

    Ericson, Thomas

    1993-01-01

    Slepians permutation codes are investigated in detail. In particular we optimize the initial vector and derive all dominating codes in dimension n 2 6. With the exception of the simplex and biorthogonal codes - which are always included as special cases of permutation codes - there are probably no further good codes in higher dimensions.

  2. Thermo-mechanical behavior of epoxy shape memory polymer foams

    Di Prima, M. A.; Lesniewski, M.; Gall, K.; McDowell, D. L.; Sanderson, T.; Campbell, D.

    2007-12-01

    Shape memory polymer foams have significant potential in biomedical and aerospace applications, but their thermo-mechanical behavior under relevant deformation conditions is not well understood. In this paper we examine the thermo-mechanical behavior of epoxy shape memory polymer foams with an average relative density of nearly 20%. These foams are deformed under conditions of varying stress, strain, and temperature. The glass transition temperature of the foam was measured to be approximately 90 °C and compression and tensile tests were performed at temperatures ranging from 25 to 125 °C. Various shape recovery tests were used to measure recovery properties under different thermo-mechanical conditions. Tensile strain to failure was measured as a function of temperature to probe the maximum recovery limits of the foam in both temperature and strain space. Compression tests were performed to examine compressibility of the material as a function of temperature; these foams can be compacted as much as 80% and still experience full strain recovery over multiple cycles. Furthermore, both tensile strain to failure tests and cyclic compression recovery tests revealed that deforming at a temperature of 80 °C maximizes macroscopic strain recovery. Deformation temperatures above or below this optimal value lead to lower failure strains in tension and the accumulation of non-recoverable strains in cyclic compression. Micro-computed tomography (micro-CT) scans of the foam at various compressed states were used to understand foam deformation mechanisms. The micro-CT studies revealed the bending, buckling, and collapse of cells with increasing compression, consistent with results from published numerical simulations.

  3. Proceedings of the first thermomechanical workshop for shale

    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

  4. On thermo-mechanical issues induced by irradiation swelling inside the back-plate of the IFMIF target assembly

    Within the framework of the IFMIF R and D program and in close cooperation with ENEA-Brasimone, at the Department of Nuclear Engineering of the University of Palermo a research campaign has been launched to investigate the thermo-mechanical issues potentially induced by irradiation swelling in the threaded connections between frame and back-plate of IFMIF target assembly. The main aim of the research campaign has relied in the assessment of the maximum swelling-induced volumetric strain that may be accepted in order to allow screws to withstand thermo-mechanical stresses and work in safe conditions or to avoid unduly high unscrewing torques during back-plate remotely handled maintenance operations. A theoretical approach based on the Finite Element Method (FEM) has been followed and a quoted commercial code has been adopted to perform the study. Since swelling-induced volumetric strain distribution within back-plate has not yet been assessed, a parametric analysis has been carried out, assuming swelling-induced volumetric strains ranging from 0.001% to 0.1%. A realistic 3D FEM model of a portion of frame and back-plate pertaining to a single screw has been set-up and a realistic set of loads and boundary conditions has been imposed. The results obtained are presented and critically discussed.

  5. The Numerical Nuclear Reactor for High-Fidelity Integrated Simulation of Neutronic, Thermal-Hydraulic, and Thermo-Mechanical Phenomena

    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.

  6. The Numerical Nuclear Reactor for High-Fidelity Integrated Simulation of Neutronic, Thermal-Hydraulic, and Thermo-Mechanical Phenomena

    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

  7. Thermomechanical CSM analysis of a superheater tube in transient state

    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.

  8. Thermomechanical behavior of rapidly solidified Fe-25Cr-20Ni

    Draissia, M.; Boukhris, N.; Debili, M.Y. [LM2S, Dept. de Physique, Faculte des Sciences, Univ. Badji-Mokhtar, Annaba, Algerie (Turkey)

    2004-07-01

    The thermomechanical treatment at 1050 C under a stress of about 30 MPa, of milled ribbons from Fe-25Cr-20Ni (0.060%Ni-0.1%Ti) refractory stainless steel, leads to a recrystallisation of the as-melt-spun structure which is intermediate between cellular and columnar dendritic. The mean grain size in the relatively high density zones (85%) may be considered as low and do not exceed 10{mu}m. Other grains appear abnormally large and reach 30 {mu}m. The origin of these grains, must be researched in an exaggerate growth phenomenon under a local deformation near the critical work hardening. (orig.)

  9. Thermomechanical Behavior of High Performance Epoxy/Organoclay Nanocomposites

    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.

  10. Thermomechanical and macropermeability experiments in the Stripa granite: status report

    The first portion of this paper reviews the status of thermomechanical experiments just completed in the time scale and full scale drifts. The second part discusses the macropermeability experiment underway in the ventilation drift. The initial results of the macropermeability experiment show that the ventilation and pressure measurement techniques applied at Stripa can be reliably employed to generate reproduceable results in the measurement of low hydraulic conductivities in large volumes of fractured rock. LBL's tests have shown, however, that the accuracy of these techniques is quite sensitive to local geological and hydrologic conditions, and this use should be carefully evaluated for each application

  11. Thermomechanical effects caused by heavy ions propagating in tissue

    The thermomechanical effects caused by ions propagating in tissue are discussed. Large energy densities in small regions surrounding ion paths cause shock waves propagating in tissue. The strength of the shock waves depends on the linear energy transfer. Molecular dynamics simulations help in determining the necessary strength of shock waves in order for the stresses caused by them to directly produce DNA strand breaks. At much smaller values of linear energy transfer, the shock waves may be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion. (authors)

  12. Technical Aspects of New Concentrating Solar Thermomechanic Conversion

    Ivan Herec

    2005-01-01

    Full Text Available The article concerns technical aspects of new concentrating solar thermo-mechanic conversion from the point of view of automated control algorithms of solar thermal motor working on a principle of modified Clausius-Rankin's thermal circulation. On the basis of the proposed algorithms for controlling of thermodynamic processes of the functional model of the solar thermal motor, which uses internal-system absorption of incoming heat radiation, double-step steam generation and regeneration of out coming heat, the design and the testing of controlling single-chip microprocessor electronics with specially designed software was executed.

  13. Thermo-mechanical interaction in nonlinear vibrating systems

    Pešek, Luděk; Půst, Ladislav

    Praha : Ústav termomechaniky AV ČR, 2003 - (Dobiáš, I.), s. 147-154 ISBN 80-85918-81-1. [Národní konference s mezinárodní účastí : Dynamika strojů. Praha (CZ), 11.02.2003-12.02.2003] R&D Projects: GA ČR GA101/02/0241 Institutional research plan: CEZ:AV0Z2076919 Keywords : thermo-mechanic interaction * non-linear * response curves Subject RIV: BI - Acoustics

  14. Grain size refinement of inconel 718 thermomechanical processing

    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)

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

    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.

  16. Thermomechanical layout of the NET first wall assembly

    The 2D-finite element (FE) method is applied for the NET first wall structure to compute the quasi-harmonic steady-state temperature distribution within the wall and to determine the nonlinear elastic stresses under thermomechanical loads. 26 different cases (as proposed) have been investigated for the structure containing plane wall, grooved wall and thin wall concepts, respectively. The wall's support condition and the nonlinear material and thermal parameters are varied. The computations are carried out once with water coolant and then with high pressure helium coolant. The results are documented in this final report. (orig./GG)

  17. Preliminary AD-Horn Thermomechanical and Electrodynamic Simulations

    Lopez Sola, Edmundo; 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. Development and validation of a fuel performance analysis code

    CAD has been developing a computer code 'FRAVIZ' for calculation of steady-state thermomechanical behaviour of nuclear reactor fuel rods. It contains four major modules viz., Thermal module, Fission Gas Release module, Material Properties module and Mechanical module. All these four modules are coupled to each other and feedback from each module is fed back to others to get a self-consistent evolution in time. The computer code has been checked against two FUMEX benchmarks. Modelling fuel performance in Advance Heavy Water Reactor would require additional inputs related to the fuel and some modification in the code.(author)

  19. A radiation change in the properties of graphite after its thermomechanical treatment

    For graphite obtained by the thermomechanical treatment method the dependence of changing sample form on neutron irradiation dose and temperature. It has been found that with formation growth during thermomechanical treatment anisotropy of properties including that of form change is inccreased. It is shown that radiation changes in modulus, electric resistance, thermal expansion coefficient are anisotropic

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

    Document available in extended abstract form only. One of the cornerstones of the nuclear waste disposal researches concerns the evolution of the damaged zone which can offer a preferential path for migration of radionuclide through modifications of its mechanical and hydraulic properties. Even if the thermo-mechanical behaviour of clays is well documented in the literature, the development of the damaged zone induced by an excavation with temperature is not well known. To investigate this problem, a new thermo-mechanical constitutive law has been implemented in the non-linear finite element code LAGAMINE developed at ULg (Universite de Liege) and has been used to model the PRACLAY experiment (Preliminary demonstration test for clay disposal of vitrified high level radioactive waste) at Mol URL (Underground Research Laboratory). Though several models are being to reproduce the different phenomena met when a thermal loading is applied to a clay specimen, the applications of such thermo-mechanical models to simulate large scale in-situ experiment are rare. Based on the work of Sultan a new thermo-mechanical constitutive law has been implemented in combination with a Cap model in the code LAGAMINE. The Cap model is a combination of a frictional criterion, a Cam-Clay model and a traction criterion. The influence of the temperature is considered through the thermo-mechanical law developed by Cui et al. (2000). This law permits to reproduce common features of the thermo-mechanical behaviour of clay, such as the decrease of the pre-consolidation pressure with temperature, the volume change, the thermal hardening, the transition between thermal dilation and thermal contraction for over-consolidated clays. These aspects are modelled with two curves in the (p',T) plane. The first one is related to the generation of the thermal volumetric plastic strains (TY curve (Thermal Yield)). The second one reproduces the decrease of the pre-consolidation pressure with the temperature

  1. Experimental identification of cohesive zone models from thermomechanical imaging techniques

    This work deals with the identification of cohesive zone models. These models were initially proposed in the 1960's. They are now more and more frequently used in numerical simulations to account for crack initiation and propagation in different materials and structures. The identification of these models still remains a delicate issue. The recent developments in imaging techniques now allow reaching local measurement fields (e.g. strain, temperature,..). We propose here to use the large amount of information given by these techniques to set up an identification procedure accounting for either the localization development (structural effect) and also the character of the different irreversibility sources encountered (thermomechanical behavior). We study damageable elasto-plastic ductile materials. Damage is associated to a cohesive behavior of the interface between volumic elements supposed to remain purely elasto-plastic. The identification procedure involves two steps. The first one consists in characterizing the shape and the parameters of the cohesive zone on tensile tests by analyzing the mechanical fields locally developed. The second one consists in checking the thermo-mechanical consistency of the identified model by confronting the calorimetric measurements deduced from temperature fields with the previsions of the identified model. This method is applied on different materials (Dual Phase steel and copper). A specific caution is conferred to the characterization of the characteristic length necessarily introduced by the identification. It is shown that this length can be estimated regarding the different parameters introduced in the image processing. (author)

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

    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.

  3. Effects Of Thermo-Mechanical Treatment On ALMG2 Alloy

    Thermo-mechanical treatment consisting of hot rolling and annealing process has been applied to ALMG2 plate. The ALMG2 plate was a dressed by hot rolling process at 400o with step deformation, and the ALMG2 plate was then annealed at 425o for one-hour. The observation on the microstructure was performed by using optical metallography, the hardness test was performed using Vickers method, and thermal conductivity was measured using conductometer. Thermo-mechanical treatment generates changes in ALMG2 microstructures and mechanical properties. The changes have been identified using optical metallography and Vickers micro hardness test. The treatment transforms the ALMG-equiaxial grain to elongated grain and the alloy hardness is still relatively soft. The hardness reaches about 58,5 Kg/mm2 after deformation of 18 %, 41 % and 76 % and 66 Kg/mm2 after deformation of 133 %. An one-our annealing treatment at 425o caused decreasing of the hardness to about (41-42) Kg/mm2 for 18 %, 41 % and 76 % deformation and to about 39 Kg/mm2 for 133 % deformation. This treatment makes the form of the grain equiaxial and the site of the grain larger. The results of the measurements using conductometer on the original ALMG2 alloy and it was addressed by hot rolling indicate that thermal conductivity of 143 W/mo to 140 W/mo

  4. Surface finishing and levelling of thermomechanically hardened rolled steel

    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)

  5. Operating experience with the Harwell thermo-mechanical generators

    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)

  6. Thermomechanical design considerations of particulate reinforced silicon carbide materials

    Much attention has been paid to silicon carbides with continuous fiber reinforcement for a large-sized core component in a fusion reactor. The choice of the toughening measures may be justified by achieving a highest fracture resistance. Many efforts in the line of a continuous SiC fiber reinforcement have been made on manufacturing optimization and materials characterization including their irradiation effects at high temperatures. According to the recent investigations on neutron irradiation effects in some experimental grade SiC/SiC composites prepared by the CVI and PIP routes, it has been emphasized that properties of continuous fiber reinforced SiC composites are controlled by fiber grade, volume fraction, weave, fiber/matrix interface and matrix properties. In parallel with these efforts for plasma facing materials and components, SiC ceramic-based composites are promising for use in a high temperature reactor (HTGR) system. In order particularly to understand their envisaged complicated behaviors under high temperature neutron irradiations, one should notice those intrinsic composite parameters that are required in a micro/mesoscopic structure-based thermomechanics approach. With this direction in mind, the paper deals with essential thermomechanical phenomena in porous polycrystalline ceramics, option on particulate reinforced SiC composites, and preparation for materials testing using the HTTR. (author)

  7. Lessons learned from the computational simulation of thermomechanical behaviour of the WWER-1000 reactor cores: FA development and its implantation into the Balakovo NPP unit 1

    The fuel assembly is forced under operation conditions by weight and hydraulic force; hold-down force; contact transversal forces; non-uniform thermal and neutron fields; thermomechanical forces in the fuel assembly multirod structure. The fuel assembly bowing has been investigated in this work. The objective of the study is to recommend the optimal design for fuel assemblies. Calculations are made using the code TEREMOK. A new generation fuel assemblies for WWER-1000 named FA-2 are suggested. The performance of the FA- 2 has been studied. The theoretical approach and the calculation technique have been verified

  8. First calculations of the thermomechanical effects following ultimate disposal of high-level radioactive wastes in a salt formation

    The thermal load of a saltdome after ultimate disposal of radioactive wastes leads to a direct heat effect, the temperature distribution, as well as a indirect heat effect, the stress/strain distribution. In the past essentially the temperature distribution had been calculated. In the mean time the thermomechanical effects of the heat dissipation will become more and more important. Therefore, the material behaviour of rock salt will be discussed and a simple mathematical description based on a rheological model will be shown. Furthermore, first results of a near field and a fare field problem in simple geometry show that the stress distribution in some parts of the calculated region is very similar to the temperature distribution. To get reliable results much researches on the material model as well as on computer codes will have to be done. (Auth.)

  9. Review of SKB's Code Documentation and Testing

    SKB is in the process of developing the SR-Can safety assessment for a KBS 3 repository. The assessment will be based on quantitative analyses using a range of computational codes aimed at developing an understanding of how the repository system will evolve. Clear and comprehensive code documentation and testing will engender confidence in the results of the safety assessment calculations. This report presents the results of a review undertaken on behalf of SKI aimed at providing an understanding of how codes used in the SR 97 safety assessment and those planned for use in the SR-Can safety assessment have been documented and tested. Having identified the codes us ed by SKB, several codes were selected for review. Consideration was given to codes used directly in SKB's safety assessment calculations as well as to some of the less visible codes that are important in quantifying the different repository barrier safety functions. SKB's documentation and testing of the following codes were reviewed: COMP23 - a near-field radionuclide transport model developed by SKB for use in safety assessment calculations. FARF31 - a far-field radionuclide transport model developed by SKB for use in safety assessment calculations. PROPER - SKB's harness for executing probabilistic radionuclide transport calculations using COMP23 and FARF31. The integrated analytical radionuclide transport model that SKB has developed to run in parallel with COMP23 and FARF31. CONNECTFLOW - a discrete fracture network model/continuum model developed by Serco Assurance (based on the coupling of NAMMU and NAPSAC), which SKB is using to combine hydrogeological modelling on the site and regional scales in place of the HYDRASTAR code. DarcyTools - a discrete fracture network model coupled to a continuum model, recently developed by SKB for hydrogeological modelling, also in place of HYDRASTAR. ABAQUS - a finite element material model developed by ABAQUS, Inc, which is used by SKB to model repository buffer

  10. ABAQUS中三维梁单元材料单轴本构模型的二次开发%Material uniaxial constitutive model secondary development of three-dimensional beam elements in ABAQUS

    袁伟泽; 陈清军

    2013-01-01

    To achieve the elastoplastic calculation of three - dimensional reinforced concrete fiber beam element in ABAQUS software, using the user - defined subroutine interface UMAT of the software implicit modules, based on the concrete constitutive theory, which combined by Mander pressure skeleton curve, Guo Zhenhai pressure loading and unloading rules and Teng Zhiming tension loading and unloading rules, and Stee102 constitutive theory of OpeenSEES, uniaxial constitutive hysteretic models for concrete and steel rebar were developed for three - dimensional fiber beam elements in ABAQUS software, then comparisons with the existing low cyclic loading test results were carried out. The results show that the user - defined material subroutines in ABAQUS software do well in simulating hysteretic behavior of the three - dimensional reinforced concrete skeletal structures.%为了在ABAQUS软件中实现对三维钢筋混凝土纤维梁单元的弹塑性计算,利用ABAQUS软件隐式模块下的用户自定义子程序接口UMAT,基于Mander受压骨架曲线、过镇海受压加卸载规则及滕智明受拉加卸载规则组合的混凝土本构理论和OpenSEES中Steel02采用的钢筋本构理论,在ABAQUS软件中开发了用于空间梁单元的混凝土和钢筋单轴本构滞回模型,并与已有的低周反复加载试验结果进行了比较.结果表明,本文基于ABAQUS软件二次开发的材料单轴滞回模型能够较好地模拟空间钢筋混凝土杆系结构的弹塑性滞回行为.

  11. Speech coding

    Gersho, Allen

    1990-05-01

    Recent advances in algorithms and techniques for speech coding now permit high quality voice reproduction at remarkably low bit rates. The advent of powerful single-ship signal processors has made it cost effective to implement these new and sophisticated speech coding algorithms for many important applications in voice communication and storage. Some of the main ideas underlying the algorithms of major interest today are reviewed. The concept of removing redundancy by linear prediction is reviewed, first in the context of predictive quantization or DPCM. Then linear predictive coding, adaptive predictive coding, and vector quantization are discussed. The concepts of excitation coding via analysis-by-synthesis, vector sum excitation codebooks, and adaptive postfiltering are explained. The main idea of vector excitation coding (VXC) or code excited linear prediction (CELP) are presented. Finally low-delay VXC coding and phonetic segmentation for VXC are described.

  12. code {poems}

    Ishac Bertran

    2012-08-01

    Full Text Available "Exploring the potential of code to communicate at the level of poetry," the code­ {poems} project solicited submissions from code­writers in response to the notion of a poem, written in a software language which is semantically valid. These selections reveal the inner workings, constitutive elements, and styles of both a particular software and its authors.

  13. Numerical simulation of thermo-mechanical fatigue properties for particulate reinforced composites

    Ran Guo; Huiji Shi; Zhenhan Yao

    2005-01-01

    In this paper, a two dimensional Voronoi cell element, formulated with creep, thermal and plastic strain, is applied for the numerical simulation of thermo-mechanical fatigue behavior for particulate reinforced composites.The relation between mechanical fatigue phases and thermal fatigue phases influences the thermo-mechanical fatigue behavior and cyclic creep damage. The topological features of micro-structure in particulate reinforced composites, such as the orientation, depth-width ratio, distribution and volume fraction of inclusions, have a great influence on thermomechanical behavior. Some related conclusions are obtained by examples of numerical simulation.

  14. Low cycle fatigue improvement of powder metallurgy titanium alloy through thermomechanical treatment

    LIU Bin; LIU Yong; HE Xiao-yu; TANG Hui-ping; CHEN Li-fang

    2008-01-01

    A low-cost β type Ti-1.5Fe-6.8Mo-4.8Al-1.2Nd (mass fraction, %)(T12LCC) alloy was produced by blended elemental powder metallurgy(P/M) method and subsequent thermomechanical treatment. Low cycle fatigue(LCF) behavior of P/M T12LCC alloy before and after thermomechanical treatment was studied. The results show that the LCF resistance of P/M titanium alloy is significantly enhanced through the thermomechanical treatment. The mechanisms for the improvement of LCF behavior are attributed to the elimination of residual pores, the microstructure refining and homogenization.

  15. Standard practice for strain controlled thermomechanical fatigue testing

    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...

  16. Structural and Thermomechanical Properties of Stove Tile Ceramics

    Anton TRNÍK

    2013-12-01

    Full Text Available The thermomechanical and thermodilatometric behavior of fired heatproof stove tile ceramic material Letovice, which contains quartz, mullite and small amounts of feldspar and glassy phase, was studied while increasing temperature up to 1100 °C. Young’s modulus was measured using the non-destructive sonic resonant method mf-TMA. To find actual dimensions of the sample, thermodilatometry was carried out at the same temperature regime as mf-TMA. A significant increase in Young’s modulus was observed in the region of the α ® b transformation of quartz. This can be explained by the healing effect of the induced radial stresses around the quartz grains on microcracks. The presence of glassy phase caused a small decrease of Young’s modulus at temperatures above ~950 °C. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2916

  17. Potential of thermomechanical processing of dilute uranium alloys

    Preliminary results of studies on uranium-2.25 wt % niobium and uranium-0.75 wt % titanium suggest that thermomechanical processing of dilute uranium alloys might: (1) eliminate the need for quenching to obtain moderate yield strengths (approx. 900 MPa), (2) provide higher usable yield strengths (> 1050 MPa). Analysis of the stress-strain curve of annealed uranium-2.25% niobium indicates that deformation hardening should produce substantial increases in yield strength with very small decreases in ductility. Preliminary rolling experiments reveal that this material can be successfully warm worked over a wide range of conditions. Analysis of the stress-strain curve of solution treated uranium-0.75% titanium indicates that deformation hardening should produce better combinations of yield strength and ductility than can be obtained by age hardening. Preliminary rolliing experiments demonstrate that this alloy can be uniformly hardened at temperatures below 3000C and that the hardening effects of deformation and aging are approximately additive

  18. A self-sustaining micro thermomechanic-pyroelectric generator

    Ravindran, S. K. T.; Huesgen, T.; Kroener, M.; Woias, P.

    2011-09-01

    Pyroelectric generators (PEGs) can be used for thermal energy harvesting and present a potential alternative to thermoelectric generators. However, in contrary to thermoelectric generators, the PEG principle requires thermal transients to stimulate the conversion process. Such suitable thermal transients are rare in nature, hindering the deployment. In this paper, we present a micro thermomechanic-pyroelectric energy generator (μTMPG) that converts a stationary spatial thermal gradient into the required transient temperature profile across the PEG. The measured power output of the μTMPG is 3 μW from a temperature difference of 79.5 K. However, with an optimized design, a power output of 39.4 mW is estimated for the same temperature difference.

  19. Thermomechanical fatigue, oxidation, and Creep: Part II. Life prediction

    Neu, R. W.; Sehitoglu, Huseyin

    1989-09-01

    A life prediction model is developed for crack nucleation and early crack growth based on fatigue, environment (oxidation), and creep damage. The model handles different strain-temperature phasings (i.e., in-phase and out-of-phase thermomechanical fatigue, isothermal fatigue, and others, including nonproportional phasings). Fatigue life predictions compare favorably with experiments in 1070 steel for a wide range of test conditions and strain-temperature phasings. An oxide growth (oxide damage) model is based on the repeated microrupture process of oxide observed from microscopic measurements. A creep damage expression, which is stress-based, is coupled with a unified constitutive equation. A set of interrupted tests was performed to provide valuable damage progression information. Tests were performed in air and in helium atmospheres to isolate creep damage from oxidation damage.

  20. Thermo-mechanical process for treatment of welds

    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

  1. Geometrical Field Formulation of Thermomechanics in Rational Mechanics

    Jianhua, Xiao

    2010-01-01

    In modern science, the thermo mechanics motion can be traced back to quantum motion in micro viewpoint. On the other hand, the thermo mechanics is definitely related with geometrical configuration motion (phase) in macro viewpoint. On this sense, the thermomechanics should be formulated by two kinds of motion: quantum motion and configuration motion. Its principle goal ought to be bridge the gap between atomic physics and engineering practice. In this research, the configuration motion is formulated by deformation geometrical field (motion transformation tensor). The quantum motion is formulated by the wave function of quantum state. Based on these two fields, the thermo stress is formulated as the coupling of quantum motion and configuration motion. Along this line, the entropy is interpreted and formulated according to thermodynamics rules. For scalar entropy, the traditional meaning of entropy is reserved. For infinitesimal configuration variation, the formulation is degenerated to the traditional elastici...

  2. Microstructure and mechanical properties of vanadium alloys after thermomechanical treatments

    The results of investigation of dispersion strengthening effect on parameters of structural-phase states and characteristics of short-term strength and ductility of vanadium alloys of V–4Ti–4Cr, V–2.4Zr–0.25C, V–1.2Zr–8.8Cr and V–1.7Zr–4.2Cr–7.6W systems with different concentration of interstitial elements after optimized thermomechanical treatment mode were summarized. It was shown that for effective realization of dispersion strengthening by Orowan-type mechanism at least 25–50% of the initial volume fraction of coarse particles should be transformed into fine-disperse state and redistributed over the volume of material

  3. Thermomechanical design of a static gas target for electron accelerators

    Brajuskovic, B; Holt, R J; Reneker, J; Meekin, D; Solvignon, P

    2013-01-01

    Gas targets are often used at accelerator facilities. A design of high-pressure gas cells that are suitable for hydrogen and helium isotopes at relatively high electron beam currents is presented. In particular, we consider rare gas targets, $^3$H$_2$ and $^3$He. In the design, heat transfer and mechanical integrity of the target cell are emphasized. ANSYS 12 was used for the thermo-mechanical studies of the target cell. Since the ultimate goal in this study was to design a gas target for use at the Jefferson Laboratory (JLab), particular attention is given to the typical operating conditions found there. It is demonstrated that an aluminum alloy cell can meet the required design goals.

  4. On the thermomechanical deformation of silver shape memory nanowires

    Park, Harold S. [Department of Civil and Environmental Engineering, Vanderbilt University, VU Station B 351831, 2301 Vanderbilt Place, Nashville, TN 37235-1831 (United States)]. E-mail: harold.park@vanderbilt.edu; Ji, Changjiang [Department of Civil and Environmental Engineering, Vanderbilt University, VU Station B 351831, 2301 Vanderbilt Place, Nashville, TN 37235-1831 (United States)

    2006-06-15

    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.

  5. Thermomechanical analysis and microstructural characterization of high performance concretes

    Ren, Fei [ORNL; Wang, Jy-An John [ORNL; Dipaolo, Beverly P [ORNL

    2012-01-01

    Ultra-high performance concrete (UHPC) is a family of emerging materials for buildings and constructions. Behaviors of UHPCs at high temperatures are very important to their reliability and safety. In the current study, two UHPC materials were studied using the thermomechanical analysis (TMA) technique between room temperature and 800oC. Both reversible and irreversible phase transformations were observed from the TMA results, which were likely due to the - quartz transformation, and the decarburization and the dehydroxylation transitions, respectively. Thermal expansion coefficients exhibited significant variations in different temperature regimes. Postmortem SEM examinations revealed extensive cracking in the heated samples. In addition, micro-porosities were observed in the C-S-H phase as a result of phase changes during heating.

  6. Thermomechanical modeling of the Spent Fuel Test-Climax

    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

  7. Mechanical and thermomechanical properties of polyamide 6/Brazilian organoclay nanocomposites

    Renê Anisio da Paz

    2016-02-01

    Full Text Available Abstract Polymer/clay nanocomposites are a new class of composites with polymer matrices where the disperse phase is a silicate with elementary particles that have at least one of dimensions in nanometer order. Polyamide 6/Brazilian organoclay nanocomposites were prepared by melt intercalation, and the mechanical, thermal and thermomechanical properties were studied. The structure and morphology of the nanocomposites were evaluated by X-ray diffraction (XRD and transmission electron microscopy (TEM. It was verified by XRD and TEM analysis that all systems presented exfoliated structure predominantly. By thermogravimetry (TG, nanocomposites showed higher stabilities in relation to pure polymer. It was observed that the nanocomposites showed better mechanical properties compared to the properties of polyamide 6. The heat deflection temperature (HDT values of the nanocomposites showed a significant increase in relation to pure polymer.

  8. A thermomechanical crystal plasticity constitutive model for ultrasonic consolidation

    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.

  9. Thermo-Mechanical Analyses of Dynamically Loaded Rubber Cylinders

    Johnson, Arthur R.; Chen, Tzi-Kang

    2002-01-01

    Thick rubber components are employed by the Army to carry large loads. In tanks, rubber covers road wheels and track systems to protect roadways. It is difficult for design engineers to simulate the details of the hysteretic heating for large strain viscoelastic deformations. In this study, an approximation to the viscoelastic energy dissipated per unit time is investigated for use in estimating mechanically induced viscoelastic heating. Coupled thermo-mechanical simulations of large cyclic deformations of rubber cylinders are presented. The cylinders are first compressed axially and then cyclically loaded about the compressed state. Details of the algorithm and some computational issues are discussed. The coupled analyses are conducted for tall and short rubber cylinders both with and without imbedded metal disks.

  10. Thermomechanical and isothermal fatigue behavior of bare and coated superalloys

    Thermomechanical fatigue (TMF) and isothermal fatigue (IF) experiments were performed on bare Mar-M246 as well as bare and coated Mar-M247 nickel based superalloys at strain ranges from 0.335 to 1 percent. The experiments were conducted in air, through a temperature range of 500 to 1,038 C at a constant strain rate of 5.0 x 10-5 s-1. Due to the coarse-grained structure of Mar-M246, TMF lives scattered considerably under low strain range conditions. Electron microscopy studies show that significant surface oxidation and gamma prime, γ', depleted zones occur for Mar-M246 under these conditions. In the surface grain, where the change in γ' morphology is most pronounced, γ' rafted along axes ∼±45 deg from the loading axis. The influence of a protective coating on the IF and TMF lives of Mar-M247 was also examined. Results indicate that the coating does not significantly affect the fatigue lives of Mar-M247. The oxidation behavior of bare and coating Mar-M247 was investigated via X-ray microprobe and Auger Spectroscopy. Through these analyses, it is evident that the coating was completely degraded when exposed to the test environment for a long time. In both Mar-M246 and Mar-M247, in-phase thermomechanical fatigue (TMF IP) loading resulted in intergranular cracking. TMF IP loading promoted multiple cracks at the coating/substrate interface of coating Mar-M247. Finally, Eshelby techniques were used to calculate stress distributions in the vicinity of a surface oxide and second-phase particle at the coating/substrate interface

  11. On the numerical assessment of the thermo-mechanical performances of the DEMO Helium-Cooled Pebble Bed breeding blanket module

    Highlights: • HCPB blanket module thermo-mechanical behavior has been investigated under normal operation and over-pressurization steady state scenarios. • A theoretical–computational approach based on the finite element method (FEM) has been followed, adopting a qualified commercial FEM code. • Under normal operation scenario, SDC-IC safety rule relevant to the loss of ductility is not fulfilled in the FW and in the hot spots of SPv. • Under over-pressurization scenario, SDC-IC safety rule relevant to the loss of ductility is not met in the hot spots of lower and upper SPv. - Abstract: Within the framework of the European DEMO Breeder Blanket Programme, a research campaign has been launched by University of Palermo, ENEA-Brasimone and Karlsruhe Institute of Technology to theoretically investigate the thermo-mechanical behavior of the Helium-Cooled Pebble Bed (HCPB) breeding blanket module of the DEMO1 blanket vertical segment, under normal operation and over-pressurization loading scenarios. 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. A realistic 3D FEM model of the HCPB blanket module central poloidal–radial region has been developed, including one breeder cell in the toroidal direction and all the five cells in the poloidal one. No Breeder Units have been modeled, their presence being simulated by effective thermo-mechanical loads. Two sets of uncoupled steady state thermo-mechanical analyses have been carried out with reference to the investigated loading scenarios. In particular, under normal operation scenario (level A) the module has been supposed to undergo both 8 MPa coolant pressure on its cooling channel walls and thermal deformations due to the flat-top plasma operational state thermal field, while under over-pressurization scenario (level D) it has been assumed to experience 8 MPa coolant pressure on its

  12. Evolution of Microstructure and Precipitation State during Thermomechanical Processing of a Low Carbon Microalloyed Steel

    Valles, P.; Gómez, Manuel; Medina, Sebastián F.; Pastor, A.; Vilanova, O.

    2012-01-01

    The increasing demand of sources of energy such as oil and natural gas induces at the steel industry a development on low carbon microalloyed steels for pipeline applications in order to achieve excellent mechanical properties of strength and toughness at a reduced cost. To obtain an adequate fine-grained final structure, the strict control of thermomechanical processing and accelerated cooling is crucial. Depending on the thermomechanical processing conditions and chemical composition, pipel...

  13. GaN-on-diamond electronic device reliability: Mechanical and thermo-mechanical integrity

    Liu, Dong; Sun, Huarui; Pomeroy, James W.; Francis, Daniel; Faili, Firooz; Twitchen, Daniel J.; Kuball, Martin

    2015-12-01

    The mechanical and thermo-mechanical integrity of GaN-on-diamond wafers used for ultra-high power microwave electronic devices was studied using a micro-pillar based in situ mechanical testing approach combined with an optical investigation of the stress and heat transfer across interfaces. We find the GaN/diamond interface to be thermo-mechanically stable, illustrating the potential for this material for reliable GaN electronic devices.

  14. GaN-on-diamond electronic device reliability: Mechanical and thermo-mechanical integrity

    The mechanical and thermo-mechanical integrity of GaN-on-diamond wafers used for ultra-high power microwave electronic devices was studied using a micro-pillar based in situ mechanical testing approach combined with an optical investigation of the stress and heat transfer across interfaces. We find the GaN/diamond interface to be thermo-mechanically stable, illustrating the potential for this material for reliable GaN electronic devices

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

    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.)

  16. Thermo-mechanical modeling of plasterboard- lined partition submitted to fire load

    Sakji, S.; Soize, Christian; Heck, J.-V.

    2006-01-01

    An important problem is the development of a thermo-mechanical model of plasterboard lined partition submitted to fire load. A fundamental key to solve such a problem is the development and the experimental validation of a deterministic and a probabilistic thermo-mechanical model of cardboard-plaster-cardboard (CPC) submitted to fire load. The proposed model takes into account system parameter uncertainties and model uncertainties. The first part concerns the constitution of an experimental t...

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

    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...

  18. Multi-Fidelity Multidisciplinary Whole Engine Thermo-Mechanical Design Optimization

    Toal, David J.J.; Keane, Andy J; Benito, Diego; Dixon, Jeffery A.; Yang, Jingbin; Price, Matthew; Robinson, Trevor; Remouchamps, Alain; Kill, Norbert

    2014-01-01

    Traditionally, the optimization of a turbomachinery engine casing for tip clearance has involved either twodimensional transient thermomechanical simulations or three-dimensional mechanical simulations. This paper illustrates that three-dimensional transient whole-engine thermomechanical simulations can be used within tip clearance optimizations and that the efficiency of such optimizations can be improved when a multifidelity surrogate modeling approach is employed. These simulations are emp...

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

    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...

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

    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.)

  1. The effects of short-lived radionuclides and porosity on the early thermo-mechanical evolution of planetesimals

    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.

  2. Thermomechanical analysis of Natural Rubber behaviour stressed at room temperature.

    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

  3. Speaking Code

    Cox, Geoff

    Speaking Code begins by invoking the “Hello World” convention used by programmers when learning a new language, helping to establish the interplay of text and code that runs through the book. Interweaving the voice of critical writing from the humanities with the tradition of computing and software...

  4. Code Cactus

    This code handles the following problems: -1) Analysis of thermal experiments on a water loop at high or low pressure; steady state or transient behavior; -2) Analysis of thermal and hydrodynamic behavior of water-cooled and moderated reactors, at either high or low pressure, with boiling permitted; fuel elements are assumed to be flat plates: - Flowrate in parallel channels coupled or not by conduction across plates, with conditions of pressure drops or flowrate, variable or not with respect to time is given; the power can be coupled to reactor kinetics calculation or supplied by the code user. The code, containing a schematic representation of safety rod behavior, is a one dimensional, multi-channel code, and has as its complement (FLID), a one-channel, two-dimensional code. (authors)

  5. Morphological features of retained austenite in thermo-mechanically processed C-Mn-Si-Al-Nb-Ti multiphase steel

    A. Grajcar

    2010-01-01

    Purpose: The aim of the paper is to determine the influence of isothermal bainitic transformation temperature on morphological features and a fraction of retained austenite in a new-developed thermo-mechanically processed C-Mn-Si-Al-Nb-Ti multiphase steel.Design/methodology/approach: The thermo-mechanical processing was realized in a multi-stage compression test by the use of the Gleeble thermomechanical simulator. The steel was isothermally held for 600 s in a bainitic transformation tempera...

  6. Thermomechanical performance of the Eu TBMs under a typical Iter transient

    Six different breeding blanket concepts will be tested in ITER under the form of six different Test Blanket Modules (TBMs). In the frame of the activities of the European TBM Consortium of Associates the Helium Cooled Pebble Bed (HCPB-TBM) and the Helium Cooled Lithium Lead (HCLL) Test Blanket Modules are developed in Karlsruhe Institute of Technology (KIT) and in CEA Saclay respectively. For each EU TBM concept, four different TBMs will be installed into one dedicated ITER equatorial port and tested during different test campaigns. The main goal of the ITER TBM program is providing DEMO relevant experimental data for the three main functions of a blanket module of a future fusion reactor, namely removing heat, breeding tritium and shielding sensitive components from radiation. The two EU TBMs share a common external structure (the so called TBM box) while featuring a different internal design of the Breeder Units (BUs), reflecting the different breeding concept. The preliminary design assessment of the two TBMs boxes is based on nuclear analyses and on the evaluation of the power produced in the BU and deposed on the TBM box structures. The preliminary thermomechanical designs have been presented and are based on steady state analyses. The TBMs will work under ITER loads, i.e. cyclic loads defined by the typical ITER pulses. Transient thermal and mechanical analyses of the two EU TBMs under a typical ITER pulse are presented in this paper, identifying the main design issues related to structural behavior of the TBM box, codes and standard rules for assessing the TBM box integrity, TBM operational domain and related DEMO relevancy of the experimental campaign. Solutions to improve the weak structural points of the present designs are proposed, identifying the missing rules and the modelling development needs. (authors)

  7. Long term thermomechanical stability of a spent fuel final repository located in granite at large depth

    The research program at INR Pitesti includes among other issues, the item of final disposal of the spent fuel from Cernavoda NPP. The heat release by the spent fuel and high radioactive waste leads to an increase of the temperature around each canister and in the granite rock. A series of processes such as canister's corrosion are dependent on the temperature. On the other hand, the temperature distribution inside the repository affects the stress and deformation state in different zones of the repository and implicitly its stability. The present work reports the results of a 3-D thermomechanical analysis carried out by means of ANSYS code for the final disposal of CANDU spent fuel from the Cernavoda NPP. The repository proposed consists in 72 parallel tunnels drilled in the granite rock at a 500 m depth. The spent fuel canisters are placed in parallel wells located at a 6 m distance from tunnel axis. The 3-D distribution of the temperature increase inside the repository after placing the fuel containers and tunnel closing are presented. The peak temperatures reached at the container's center and on its surface amount about 134 deg. C and 116 deg. C, respectively. These temperature values were reached at 25 years after containers' disposal inside the repository. Also, the stress distribution directly after excavation and after 25 years from containers' disposal was evaluated. The highest values of the axial stress were obtained in the canister's vicinity and at the tunnel ends. To evaluate the rock stability directly after excavation and at 25 years after containers' disposal the Hoek and Brown braking criterion was used

  8. Analysis of the thermo-mechanical deformations in a hot forging tool by numerical simulation

    L-Cancelos, R.; Varas, F.; Martín, E.; Viéitez, I.

    2016-03-01

    Although programs have been developed for the design of tools for hot forging, its design is still largely based on the experience of the tool maker. This obliges to build some test matrices and correct their errors to minimize distortions in the forged piece. This phase prior to mass production consumes time and material resources, which makes the final product more expensive. The forging tools are usually constituted by various parts made of different grades of steel, which in turn have different mechanical properties and therefore suffer different degrees of strain. Furthermore, the tools used in the hot forging are exposed to a thermal field that also induces strain or stress based on the degree of confinement of the piece. Therefore, the mechanical behaviour of the assembly is determined by the contact between the different pieces. The numerical simulation allows to analyse different configurations and anticipate possible defects before tool making, thus, reducing the costs of this preliminary phase. In order to improve the dimensional quality of the manufactured parts, the work presented here focuses on the application of a numerical model to a hot forging manufacturing process in order to predict the areas of the forging die subjected to large deformations. The thermo-mechanical model developed and implemented with free software (Code-Aster) includes the strains of thermal origin, strains during forge impact and contact effects. The numerical results are validated with experimental measurements in a tooling set that produces forged crankshafts for the automotive industry. The numerical results show good agreement with the experimental tests. Thereby, a very useful tool for the design of tooling sets for hot forging is achieved.

  9. Thermomechanical fatigue behavior of Sn-Ag solder joints

    Choi, S.; Subramanian, K. N.; Lucas, J. P.; Bieler, T. R.

    2000-10-01

    Microstructural studies of thermomechanically fatigued actual electronic components consisting of metallized alumina substrate and tinned copper lead, soldered with Sn-Ag or 95.5Ag/4Ag/0.5Cu solder were carried out with an optical microscope and environmental scanning electron microscope (ESEM). Damage characterization was made on samples that underwent 250 and 1000 thermal shock cycles between -40°C and 125°C, with a 20 min hold time at each extreme. Surface roughening and grain boundary cracking were evident even in samples thermally cycled for 250 times. The cracks were found to originate on the free surface of the solder joint. With increased thermal cycles these cracks grew by grain boundary decohesion. The crack that will affect the integrity of the solder joint was found to originate from the free surface of the solder very near the alumina substrate and progress towards and continue along the solder region adjacent to the Ag3Sn intermetallic layer formed with the metallized alumina substrate. Re-examination of these thermally fatigued samples that were stored at room temperature after ten months revealed the effects of significant residual stress due to such thermal cycles. Such observations include enhanced surface relief effects delineating the grain boundaries and crack growth in regions inside the joint.

  10. Thermomechanical Impact of Polyurethane Potting on Gun Launched Electronics

    A. S. Haynes

    2013-01-01

    Full Text Available Electronics packages in precision guided munitions are used in guidance and control units, mission computers, and fuze-safe-and-arm devices. They are subjected to high g-loads during gun launch, pyrotechnic shocks during flight, and high g-loads upon impact with hard targets. To enhance survivability, many electronics packages are potted after assembly. The purpose of the potting is to provide additional structural support and shock damping. Researchers at the US Army recently completed a series of dynamic mechanical tests on a urethane-based potting material to assess its behavior in an electronics assembly during gun launch and under varying thermal launch conditions. This paper will discuss the thermomechanical properties of the potting material as well as simulation efforts to determine the suitability of this potting compound for gun launched electronics. Simulation results will compare stresses and displacements for a simplified electronics package with and without full potting. An evaluation of the advantages and consequences of potting electronics in munitions systems will also be discussed.

  11. Microstructure and Thermomechanical Properties of Magnesium Alloys Castings

    P. Lichý

    2012-04-01

    Full Text Available Magnesium alloys thanks to their high specific strength have an extensive potential of the use in a number of industrial applications. The most important of them is the automobile industry in particular. Here it is possible to use this group of materials for great numbers of parts from elements in the car interior (steering wheels, seats, etc., through exterior parts (wheels particularly of sporting models, up to driving (engine blocks and gearbox mechanisms themselves. But the use of these alloys in the engine structure has its limitations as these parts are highly thermally stressed. But the commonly used magnesium alloys show rather fast decrease of strength properties with growing temperature of stressing them. This work is aimed at studying this properties both of alloys commonly used (of the Mg-Al-Zn, Mn type, and of that ones used in industrial manufacture in a limited extent (Mg-Al-Sr. These thermomechanical properties are further on complemented with the microstructure analysis with the aim of checking the metallurgical interventions (an effect of inoculation. From the studied materials the test castings were made from which the test bars for the tensile test were subsequently prepared. This test took place within the temperature range of 20°C – 300°C. Achieved results are summarized in the concluding part of the contribution.

  12. Thermomechanical analyses of phenolic foam reinforced with glass fiber mat

    Highlights: • Over 10% glass fiber was used to reinforce phenolic foam in the shape of glass fiber mat. • Nucleating agents were used together with glass fiber mat and improved tensile strength of phenolic foam by 215.6%. • Nucleating agents lead to a smaller bubble size of phenolic foam. • The glass transition temperature of phenolic foam remained unchanged during the reinforcement. - Abstract: In this paper, thermomechanical analysis (TMA) and dynamic mechanical analysis were employed to study the properties of phenolic foam reinforced with glass fiber mat. Unreinforced phenolic foam was taken as the control sample. Mechanical tests and scanning electron microscopy were performed to confirm the results of TMA. The results show that glass fiber mat reinforcement improves the mechanical performance of phenolic foam, and nucleating agents improve it further. Phenolic foam reinforced with glass fiber mat has a smaller thermal expansion coefficient compared with unreinforced foam. The storage modulus of the reinforced phenolic foam is also higher than that in unreinforced foam, whereas the loss modulus of the former is lower than that of the latter. The glass transition temperature of the phenolic foam matrix remains unchanged during the reinforcement

  13. Micromechanisms of thermomechanical fatigue: A comparison with isothermal fatigue

    Bill, R. C.

    1986-01-01

    Thermomechanical Fatigue (TMF) experiments were conducted on Mar-M 200, B-1900, and PWA-1480 (single crystals) over temperature ranges representative of gas turbine airfoil environments. The results were examined from both a phenomenological basis and a micromechanical basis. Depending on constituents present in the superalloy system, certain micromechanisms dominated the crack initiation process and significantly influenced the TMF lives as well as sensitivity of the material to the type TMF cycle imposed. For instance, high temperature cracking around grain boundary carbides in Mar-M 200 resulted in short in-phase TMF lives compared to either out-of-phase or isothermal lives. In single crystal PWA-1480, the type of coating applied was seen to be the controlling factor in determining sensitivity to the type of TMF cycle imposed. Micromechanisms of deformation were observed over the temperature range of interest to the TMF cycles, and provided some insight as to the differences between TMF damage mechanisms and isothermal damage mechanisms. Finally, the applicability of various life prediction models to TMF results was reviewed. Current life prediction models based on isothermal data must be modified before being generally applied to TMF.

  14. The development of heat exchangers with advanced thermomechanical materials

    Current metallurgical limitations necessarily impose a number of restrictions on the efficiency of power plant and combustion systems. These limitations include both temperature and corrosion resistance. If significant improvements can be made in these areas, then not only will it be possible to obtain higher system efficiencies, but it will also be possible to further exploit new technologies. Consequently, there is appreciable interest in the development of ceramic tubes for heat exchangers. Such tubes would offer the potential of operation at much higher temperatures combined with a much improved resistance to chemical attack. They are unlikely to be suitable for high pressure operation, at least in the foreseeable future, and hence their use would be limited generally to gas to gas exchangers. In spite of the limitations on details and specific technological solutions imposed by industrial property conditions, this report provides an overview on the development of these components, which is in charge of all the major international industrial companies of the field, in consideration of the relevant benefits coming from their large industrialization. After an analysis of the industrial situation of the product, in terms both of possible applications and economical impacts on the market, an overview of major on-going R and D programmes is carried out. At present, these programmes are mostly within the general frame of the study of advanced thermomechanical components and the related manufacturing technologies development

  15. Thermomechanical response of inhibited carbon-carbon composites

    Analytical models to capture the additional inhomogeneities such as boron carbide particulates added to enhance the oxidation resistance of carbon-carbon composites are developed. In parallel, the test results of laminates subjected to static and fatigue loading at ambient and high temperature (900 C) are monitored so that an interactive numerical simulation and observation procedure can be developed. The material system studied is HITCO 2D CC137EH, highly inhibited, eight harness satin weave, RT42 CVD SiC coated, carbon-carbon laminate. The static testing to date focuses on generating the upper bound loads to be used in the thermomechanical fatigue tests. The stress-strain response obtained from the static tension tests reveal a region of nonlinearity which is attributed to the presence of the porosity, the microcracking and the inhibitors. The significant number of oxidation tests of coated as well as partially uncoated specimens clearly indicate the preferential oxidation along the fiber bundles perpendicular to the exposed edges

  16. Thermomechanical Analysis of Shape-Memory Composite Tape Spring

    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.

  17. Progress with thermomechanical investigations of the Stripa site

    The Stripa mine in Sweden has provided an unusual opportunity to investigate the thermomechanical behavior of a granitic rock mass and the effect on such behavior of the discontinuities that are a persistent feature. Experiments to simulate the thermal effects of burying radioactive wastes have been carried out at a depth of about 340m. All of the thousands of underground measurements of temperatures, displacements, and stresses in the rock, recorded continuously over this period, have been made available on digital tape and in hard copy. This paper presents some results of recent investigations. Although temperature fields predicted by calculations based on linear heat conduction compare well with measured field data, evidence for some convective heat transfer has been found. Measured values of displacements have been significantly less than those predicted by calculations. Evidence that these displacements are diminished by fractures in the granite has been found. A program of laboratory investigations has been started to measure coefficients of thermal expansion and elastic moduli for Stripa granite. USAP (Underground Structural Analysis Program) is a unique finite element program that has been developed specifically for the analysis of underground structures; it has the potential to be used effectively in general problems associated with the underground storage of nuclear waste

  18. Progress in thermomechanical control of steel plates and their commercialization

    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.

  19. Progress in thermomechanical control of steel plates and their commercialization

    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. (topical review)

  20. Low cycle fatigue behavior of thermo-mechanically treated rebar

    Highlights: • Strain and stress controlled low cycle fatigue behavior of TMT rebar. • Decrease in the cyclic yield stress is responsible for cyclic softening of TMT rebar. • Fatigue crack initiates form the transverse rib root and propagate along the same region. • Stress concentration and high stress triaxiality observed at the root of the transverse rib. - Abstract: The strain and stress controlled low cycle fatigue behavior of thermo-mechanically treated rebar are examined in this current work at room temperature. Severe cyclic softening is observed in all applied strain amplitudes during strain controlled low cycle fatigue. Cyclic softening deteriorates the seismic resistance property of the rebar. Decrease in the cyclic yield stress (linear portion of the hysteresis loop) is responsible for cyclic softening. Cyclic softening results progressive opening up the hysteresis loop during stress controlled low cycle fatigue. It is experimentally observed that irrespective of control mode (stress/strain) and loading conditions, fatigue crack initiates form the transverse rib root and propagate along the same region. Finite element simulation result reveal that stress concentration takes place at the root of the transverse rib and stress triaxiality become higher in the same region. Tensile strain accumulation at the transverse rib root is detected in simulation. Simulation result explains the experimental fact that fatigue crack initiate and propagate along the transverse rib root

  1. The AMP (Advanced MultiPhysics) Nuclear Fuel Performance code

    Highlights: ► New, three-dimensional, parallel, multi-physics code to simulate fuel behavior in nominal operation. ► Fully-coupled thermomechanics for nominal operation and operation during transients. ► Isotopic depletion using Scale/ORIGEN-S within a fuel performance code. ► Leveraging of existing, validated material models from existing fuel performance codes. ► Initial validation evaluation of an advanced modeling and simulation code for fuel performance. - Abstract: The AMP (Advanced MultiPhysics) Nuclear Fuel Performance code is a new, three-dimensional, multi-physics tool that uses state-of-the-art solution methods and validated nuclear fuel models to simulate the nominal operation and anticipated operational transients of nuclear fuel. The AMP Nuclear Fuel Performance code leverages existing validated material models from traditional fuel performance codes and the Scale/ORIGEN-S spent-fuel characterization code to provide an initial capability that is shown to be sufficiently accurate for a single benchmark problem and anticipated to be accurate for a broad range of problems. The thermomechanics foundation can be solved in a time-dependent or quasi-static approach with any variation of operator-split or fully-coupled solutions at each time step through interoperable interfaces to leading computational mathematics tools, including PETSc, Trilinos, and SUNDIALS. A baseline validation of the AMP Nuclear Fuel Performance code has been performed through the modeling of an experiment in the Halden Reactor Project (IFA-432) that demonstrates the integrated capability and provides a baseline of the initial accuracy of the software.

  2. Free Vibration Analysis for Layered Shells Accounting of Variable Kinematic and Thermo-Mechanical Coupling

    S. Brischetto

    2012-01-01

    Full Text Available The free vibration analysis of one-layered and two-layered metallic cylindrical shell panels is evaluated in this work. The free frequency values are investigated for both thermo-mechanical and pure mechanical problems. Thermo-mechanical frequencies are calculated by means of a fully coupled thermo-mechanical model where both the displacement and temperature are primary variables in the considered governing equations. Pure mechanical frequencies are obtained from a mechanical model where the effect of the temperature field is not included in the stiffness matrix and the displacement is the only primary variable of the problem. The inclusion of the thermal part in the stiffness matrix gives larger frequencies. Both thermo-mechanical and pure mechanical models are developed in the framework of Carrera's Unified Formulation (CUF in order to obtain several variable kinematic models. Both equivalent single layer and layer wise approaches are considered for multilayered shells. The use of refined two-dimensional theories for shells permits the evaluation of the effects of the thermo-mechanical coupling for lower and higher order modes, higher frequency values, multilayered configurations, thick and thin shells and several values of the radius of curvature of the shell geometry. It has mainly been concluded that the thermo-mechanical coupling is not influenced by the curvature of the shells, therefore, the main conclusions already given for the plate geometry are here confirmed: – the thermo-mechanical coupling is correctly determined if both the thermal and mechanical parts are correctly approximated; – it is small for each investigated case; – it influences the various vibration modes in different ways; – it has a limited dependence on the considered case, but this dependence vanishes if a global coupling is considered.

  3. The effect of beam interruptions on the integrity of ADSR fuel pin cladding: A thermo-mechanical analysis

    Highlights: ► We present beam interruption data for four high power proton accelerators. ► We extend the PTS-ADS code capabilities to include a thermal stress Subroutine. ► We study the thermo-mechanical response in an ADSR cladding to unplanned beam interruptions. ► We perform a thermal fatigue analysis. ► The cladding integrity is severely affected if the current accelerator technology is deployed. - Abstract: During its lifetime in the core, the cladding of an Accelerator Driven Subcritical Reactor (ADSR) fuel pin is expected to experience variable stresses due to frequent interruptions in the accelerator proton beam. This paper investigates the thermal fatigue damage in the cladding due to repetitive and unplanned beam interruptions under certain operational conditions. Beam trip data was obtained for four operating high power proton accelerators, among which the Spallation Neutron Source (SNS) superconducting accelerator was selected for further analysis. 9Cr–1Mo–Nb–V (T91) steel was selected as the cladding material because of its proven compatibility with proposed ADSR design concepts. The neutronic, thermal and stress analyses were performed using the PTS-ADS, a code that has been specifically developed for studying the dynamic response to beam-induced transients in accelerator driven subcritical systems. The lifetime of the fuel cladding in the core was estimated for three levels of allowed pin power and specific operating conditions.

  4. Thermomechanical evaluation of BWR fuel elements for procedures of preconditioned with FEMAXI-V; Evaluacion termomecanica de elementos combustible BWR para procedimientos de preacondicionado con FEMAXI-V

    Hernandez L, H.; Lucatero, M.A.; Ortiz V, J. [ININ, Carretera Mexico-Toluca Km 36.5, La Marquesa, Estado de Mexico (Mexico)]. e-mail: hhl@nuclear.inin.mx

    2006-07-01

    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)

  5. 基于ABAQUS的钢轨铝热焊接接头的有限元分析%The Finite Element Analysis of Rail Thermite Welding Joint on ABAQUS

    侯健

    2013-01-01

    A finite element model of rail welding joint is built with the finite element software ABAQUS,and the ABAQUS is used to analyze the mechanical properties of rail thermite welding joint under the pure rolling condition and pure sliding contion.Then basing on the analysis of the pure rolling wheel-rail contact,study the influence of the performance parameters such as speed of train,position of welding joint,width of welding zone.The results show that the sliding wheel-rail contact do harm to welding joint,the speed of train,positionof welding joint and width of welding zone has considerable effects on the mechanical properties of welding joints.%运用有限元软件ABAQUS强大的处理功能建立了钢轨铝热焊接接头弹塑性分析的有限元模型,并在此基础上进行轮轨纯滚动接触和全滑动接触两种工况下的焊接接头力学性能分析;然后在纯滚动接触的基础上,研究各项性能参数如车速、焊接接头位置、焊缝热影响区宽度、接头不平顺及波深等的影响.结果表明,轮轨滑动接触对接头损伤较大,车速、焊接接头位置、焊缝热影响区宽度对焊接接头力学性能有重要影响.

  6. Fe Simulation of Cutting Status when High Speed Machining the Ti-6Al-4V Based on Abaqus%基于ABAQUS高速切削Ti-6Al-4V切削状态的有限元仿真

    冯吉路; 姜增辉

    2013-01-01

    A high speed orthogonal cutting Ti-6AMV of Johnson-Cook materials model and fracture criterion was established by Abaqus/Explicit. The influence of cutting speed, cutting depth, tool rake angel on the average cutting force and the chip morphology was discussed respectively. The investigation indicate that serrated degree of chips and teeth space was increased when increasing cutting speed and cutting depth, while tool rake angel is just the opposite. And the average cutting force was steadied during the cutting speed coming up to 60m/min-180m/min, it was increased with the increase of cutting depth, cutting force decreased with the increase of tool rake angel.%文章基于Abaqus/Explicit的Johnson-Cook材料模型以及断裂准则模拟高速正交切削Ti-6Al-4V,仿真分析了切削速度、切削深度、刀具前角变化时对平均切削力以及锯齿状切屑形态的影响.研究结果表明:切屑锯齿化程度和齿距随切削速度和切削深度的增加而增大,随前角的增加而减小.平均切削力在切削速度为60m/min-180m/min时趋于平稳,随切削深度增加而增大,随前角增大而减小.

  7. RAPTA-5 code: Modelling behaviour of WWER-type fuel rods in design basis accidents verification calculations

    RAPTA-5 code used for licensing calculations to validate the compliance with the requirements for WWER fuel safety in design basis accidents. The characteristic results are given of design modelling experiments simulating thermomechanical and corrosion behaviour of WWER and PWR fuel rods in LOCA. The results corroborate the adequate predictability of both individual design models and the code as a whole. (author). 14 refs, 12 figs

  8. Optimal codes as Tanner codes with cyclic component codes

    Høholdt, Tom; Pinero, Fernando; Zeng, Peng

    2014-01-01

    In this article we study a class of graph codes with cyclic code component codes as affine variety codes. Within this class of Tanner codes we find some optimal binary codes. We use a particular subgraph of the point-line incidence plane of A(2,q) as the Tanner graph, and we are able to describe ...

  9. Speech coding

    Ravishankar, C., Hughes Network Systems, Germantown, MD

    1998-05-08

    Speech is the predominant means of communication between human beings and since the invention of the telephone by Alexander Graham Bell in 1876, speech services have remained to be the core service in almost all telecommunication systems. Original analog methods of telephony had the disadvantage of speech signal getting corrupted by noise, cross-talk and distortion Long haul transmissions which use repeaters to compensate for the loss in signal strength on transmission links also increase the associated noise and distortion. On the other hand digital transmission is relatively immune to noise, cross-talk and distortion primarily because of the capability to faithfully regenerate digital signal at each repeater purely based on a binary decision. Hence end-to-end performance of the digital link essentially becomes independent of the length and operating frequency bands of the link Hence from a transmission point of view digital transmission has been the preferred approach due to its higher immunity to noise. The need to carry digital speech became extremely important from a service provision point of view as well. Modem requirements have introduced the need for robust, flexible and secure services that can carry a multitude of signal types (such as voice, data and video) without a fundamental change in infrastructure. Such a requirement could not have been easily met without the advent of digital transmission systems, thereby requiring speech to be coded digitally. The term Speech Coding is often referred to techniques that represent or code speech signals either directly as a waveform or as a set of parameters by analyzing the speech signal. In either case, the codes are transmitted to the distant end where speech is reconstructed or synthesized using the received set of codes. A more generic term that is applicable to these techniques that is often interchangeably used with speech coding is the term voice coding. This term is more generic in the sense that the

  10. Effect of Thermo-mechanical Treatment on Mechanical Properties of Korean RAFM steel

    Advanced reduced-activation alloy (ARAA) of Korean RAFM steels was developed by Korea Atomic Energy Research Institute (KAERI) and National Fusion Research Institute (NFRI). Thermo-mechanical treatment (TMT) has been known to be effective to improvement in mechanical properties of several RAFM steels by introducing high densities of dislocations and fine precipitates. This study examines the effect of thermo-mechanical treatment on the microstructure and mechanical properties of ARAA alloy. The effects of thermo-mechanical treatment on microstructure and mechanical properties were studied. TMT consisting of austenitizing and 20% hot-rolling at 700 .deg. C significantly enhances both tensile strength and impact property of ARAA, which suggests that a TMT is a promising way of improving mechanical properties of RAFM steels

  11. Semi-analytical solution of time-dependent thermomechanical creep behavior of FGM hollow spheres

    Jafari Fesharaki, J.; Loghman, A.; Yazdipoor, M.; Golabi, S.

    2014-02-01

    By using a method of successive elastic solution, the time-dependent creep behavior of a functionally graded hollow sphere under thermomechanical loads has been investigated. Based on volume percentage, the mechanical and thermal properties of material, except for the Poisson's ratio, are assumed to be radially dependent. Total strains are assumed to be the sum of elastic, thermal and creep strains. Creep strains are temperature-, stress- and time-dependent. Using the Prandtl-Reuss relations and Sherby's law, histories of stresses and strains are presented from their initial elastic values at zero time up to 30 years after loading. The results show that the creep stresses and strains change with time and material inhomogeneity has influence on thermomechanical creep behavior. The aim of this work was to understand the effect of creep behavior on a functionally graded hollow sphere subjected to thermomechanical load.

  12. An anisotropic thermomechanical damage model for concrete at transient elevated temperatures.

    Baker, Graham; de Borst, René

    2005-11-15

    The behaviour of concrete at elevated temperatures is important for an assessment of integrity (strength and durability) of structures exposed to a high-temperature environment, in applications such as fire exposure, smelting plants and nuclear installations. In modelling terms, a coupled thermomechanical analysis represents a generalization of the computational mechanics of fracture and damage. Here, we develop a fully coupled anisotropic thermomechanical damage model for concrete under high stress and transient temperature, with emphasis on the adherence of the model to the laws of thermodynamics. Specific analytical results are given, deduced from thermodynamics, of a novel interpretation on specific heat, evolution of entropy and the identification of the complete anisotropic, thermomechanical damage surface. The model is also shown to be stable in a computational sense, and to satisfy the laws of thermodynamics. PMID:16243703

  13. Effect of Thermo-mechanical Treatment on Mechanical Properties of Korean RAFM steel

    Kim, M. S.; Chun, Y. B.; Lee, D. W.; Lee, C. K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cho, S. Y. [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Advanced reduced-activation alloy (ARAA) of Korean RAFM steels was developed by Korea Atomic Energy Research Institute (KAERI) and National Fusion Research Institute (NFRI). Thermo-mechanical treatment (TMT) has been known to be effective to improvement in mechanical properties of several RAFM steels by introducing high densities of dislocations and fine precipitates. This study examines the effect of thermo-mechanical treatment on the microstructure and mechanical properties of ARAA alloy. The effects of thermo-mechanical treatment on microstructure and mechanical properties were studied. TMT consisting of austenitizing and 20% hot-rolling at 700 .deg. C significantly enhances both tensile strength and impact property of ARAA, which suggests that a TMT is a promising way of improving mechanical properties of RAFM steels.

  14. The temperature memory effect and the influence of thermo-mechanical cycling in shape memory alloys

    Apart from the well-known shape memory effect (SME), the temperature memory effect (TME), i.e., the ability of a material to remember the heating interrupted temperature in the previous thermal cycle, is another interesting phenomenon observed in many shape memory alloys (SMAs). In this paper, based on previous and current experimental observations, we propose a phenomenological model to reproduce the TME. Subsequently, we study the influence of thermo-mechanical cycling (uniaxial tension) on the TME in a polycrystalline NiTi SMA wire (0.51 mm diameter). The maximum tensile strain in each cycle is 10%, which is beyond its elastic limit. The evolution of the peak transition temperature in the forward and reverse transformations and the TME upon thermo-mechanical cycling is investigated by differential scanning calorimetry. It is proved that the TME is a stable intrinsic phenomenon and can be utilized even under severe thermo-mechanical conditions

  15. NSURE code

    NSURE stands for Near-Surface Repository code. NSURE is a performance assessment code. developed for the safety assessment of near-surface disposal facilities for low-level radioactive waste (LLRW). Part one of this report documents the NSURE model, governing equations and formulation of the mathematical models, and their implementation under the SYVAC3 executive. The NSURE model simulates the release of nuclides from an engineered vault, their subsequent transport via the groundwater and surface water pathways tot he biosphere, and predicts the resulting dose rate to a critical individual. Part two of this report consists of a User's manual, describing simulation procedures, input data preparation, output and example test cases

  16. Influence of thermomechanical aging on fatigue behaviour of 2014 Al-alloy

    S Singh; D B Goel

    2005-04-01

    The fatigue behaviour of 2014 Al-alloy has been studied in various thermomechanically aged conditions. It is observed that fatigue properties can be improved by a thermomechanical treatment, which would reduce the concentrations of dispersoids, provide a relatively uniform deformation structure and produce fine distribution of ' precipitates. Fine ' particles inhibit dynamic recovery and produce uniform deformation structure, which improves fatigue behaviour. Presence of dispersoids and coarse precipitate particles leads to the formation of persistent slip bands (PSBs) and a highly heterogeneous deformation structure, which cause damage to fatigue properties.

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

    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

  18. Thermomechanical simulation of the selective laser melting process for PA12 including volumetric shrinkage

    Riedlbauer, D.; Steinmann, P.; Mergheim, J.

    2015-05-01

    The present contribution is concerned with the finite element simulation of the thermomechanical material behavior in the selective laser melting process for PA12. In the process shrinkage of the powder material is observed when becoming melt, as the porous character of the powder vanishes due to the phase transition. A nonlinear thermomechanical finite element model is developed, which captures the shrinkage of the material and includes temperature dependent material parameters. The model is used to simulate the shrinkage of the material in the process, where an adaptive mesh refinement is applied for increasing the accuracy of the simulation. The results are qualitatively compared with experimental data and show a good agreement.

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

    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.

  20. Obtaining an Acicular Microstructure by Thermomechanical Sequences in X-80 Steel

    de Castro, Renato Soares; Pedrosa, Igor Rafael Vilarouco; Yadava, Yogendra Prasad; Ferreira, Ricardo Artur Sanguinetti

    2014-09-01

    Microstructural modification is one of the routes to increase strength and toughness in high-strength low-alloy (HSLA) steels. Considering the good mechanical properties of acicular ferrite, thermomechanical sequences, with continuous cooling or isothermal treatment, were applied in an X-80 HSLA steel to obtain dominant acicular microstructure. Electron microscopy and electron back-scattered diffraction (EBDS) analyses were performed to identify and quantify microstructural changes. It was possible to correlate the misorientation boundaries profile with the occurrence of acicular microstructure, which was characterized by a high quantity of substructured and deformed units. Thermomechanical sequences with continuous cooling were more effective for obtaining acicular microstructure than sequences of isothermal treatments.

  1. The Aster code; Code Aster

    Delbecq, J.M

    1999-07-01

    The Aster code is a 2D or 3D finite-element calculation code for structures developed by the R and D direction of Electricite de France (EdF). This dossier presents a complete overview of the characteristics and uses of the Aster code: introduction of version 4; the context of Aster (organisation of the code development, versions, systems and interfaces, development tools, quality assurance, independent validation); static mechanics (linear thermo-elasticity, Euler buckling, cables, Zarka-Casier method); non-linear mechanics (materials behaviour, big deformations, specific loads, unloading and loss of load proportionality indicators, global algorithm, contact and friction); rupture mechanics (G energy restitution level, restitution level in thermo-elasto-plasticity, 3D local energy restitution level, KI and KII stress intensity factors, calculation of limit loads for structures), specific treatments (fatigue, rupture, wear, error estimation); meshes and models (mesh generation, modeling, loads and boundary conditions, links between different modeling processes, resolution of linear systems, display of results etc..); vibration mechanics (modal and harmonic analysis, dynamics with shocks, direct transient dynamics, seismic analysis and aleatory dynamics, non-linear dynamics, dynamical sub-structuring); fluid-structure interactions (internal acoustics, mass, rigidity and damping); linear and non-linear thermal analysis; steels and metal industry (structure transformations); coupled problems (internal chaining, internal thermo-hydro-mechanical coupling, chaining with other codes); products and services. (J.S.)

  2. Beyond Stabilizer Codes II: Clifford Codes

    Klappenecker, Andreas; Roetteler, Martin

    2000-01-01

    Knill introduced a generalization of stabilizer codes, in this note called Clifford codes. It remained unclear whether or not Clifford codes can be superior to stabilizer codes. We show that Clifford codes are stabilizer codes provided that the abstract error group has an abelian index group. In particular, if the errors are modelled by tensor products of Pauli matrices, then the associated Clifford codes are necessarily stabilizer codes.

  3. MCNP code

    The MCNP code is the major Monte Carlo coupled neutron-photon transport research tool at the Los Alamos National Laboratory, and it represents the most extensive Monte Carlo development program in the United States which is available in the public domain. The present code is the direct descendent of the original Monte Carlo work of Fermi, von Neumaum, and Ulam at Los Alamos in the 1940s. Development has continued uninterrupted since that time, and the current version of MCNP (or its predecessors) has always included state-of-the-art methods in the Monte Carlo simulation of radiation transport, basic cross section data, geometry capability, variance reduction, and estimation procedures. The authors of the present code have oriented its development toward general user application. The documentation, though extensive, is presented in a clear and simple manner with many examples, illustrations, and sample problems. In addition to providing the desired results, the output listings give a a wealth of detailed information (some optional) concerning each state of the calculation. The code system is continually updated to take advantage of advances in computer hardware and software, including interactive modes of operation, diagnostic interrupts and restarts, and a variety of graphical and video aids

  4. ANIMAL code

    This report describes ANIMAL, a two-dimensional Eulerian magnetohydrodynamic computer code. ANIMAL's physical model also appears. Formulated are temporal and spatial finite-difference equations in a manner that facilitates implementation of the algorithm. Outlined are the functions of the algorithm's FORTRAN subroutines and variables

  5. Thermo-mechanical phenomena in high speed continuous casting processes

    Park, Joong Kil

    Thermo-mechanical phenomena during continuous thin slab casting have been studied with the objectives of understanding the mechanism of mold crack formation, and the effect of mold design upon the mechanical behavior of the stand. To achieve these goals, several finite element models have been developed in conjunction with a series of industrial plant trials. First, an investigation of mold crack formation in thin slab casting was undertaken to elucidate the mechanism by which cracks develop and to evaluate possible solutions to the problem. Three-dimensional finite-element thermal-stress models were developed to predict temperature, distortion, and residual stress in thin-slab casting molds, comparing funnel-shaped to parallel molds. Mold wall temperatures were obtained from POSCO in Korea and analyzed to determine the corresponding heat-flux profiles in thin-slab molds. This data was utilized in an elastic-visco-plastic analysis to investigate the deformation of the molds in service for the two different mold shapes. The results of a metallurgical investigation of mold samples containing cracks were used together with the results of the mathematical models, to determine mechanisms and to suggest solutions for the formation of mold cracks. Large cyclic inelastic strains were found in the funnel transition region just below the meniscus, due to the slightly higher temperature at that location. The cracks appear to have propagated by thermal fatigue caused by major level fluctuations. Next, two-dimensional thermo-elastic-visco-plastic analysis was performed for a horizontal slice of the solidifying strand, which moves vertically down the mold during casting. The model calculates the temperature distributions, the stresses and the strains in the solidifying shell, and the air gap between the casting mold and the solidifying strand. Model predictions were verified with an analytical solution and plant trials that were carried out during billet casting at POSCO. The

  6. 基于ABAQUS强度折减法某铀尾矿坝稳定性分析%The Analysis of a Uranium Tailings Dam Stability Based on ABAQUS Strength Reduction Method

    周薛淼; 刘永; 李国辉; 卢继鹰

    2016-01-01

    From the combination of the finite software of ABAQUS and strength reduction method,making full use of powerful post-processing ability of ABAQUS,this study analyzes a uranium tailings dam stability.The displacement mutation of slope feature control points and plastic zone breakthrough of slipping plane from the dam slope toe to top are used as a sym-bol of the whole slope instability.When plastic zone in the slope sliding surface is connected from the slope toe to top, plastic strain and displacement of characteristic control points result in mutation,the dam slope is in a critical state of sliding failure,while the strength re-duction factor is defined as the minimum safety coefficient of dam slope stability.Through an example of a uranium tailings dam stability analysis, it can predict accurately and vividly dam slope potential sliding surface position and evaluate the stability of dam slop,especially for the stability analysis of complex terrain slope,which is a simple and practicable method.%将ABAQUS有限元软件和强度折减法相结合,充分利用ABAQUS的强大后处理能力对某一铀尾矿坝稳定性进行分析。通过把坡面的特征控制点的位移突变和滑移面塑性区从坡脚到坡顶的贯通作为边坡整体失稳的标志,当滑移面的塑性区贯通,塑性应变和特征控制点的位移发生突变时,则坝坡就处于滑动破坏临界状态,而此时的强度折减系数就定义为坝坡稳定的最小安全系数。通过某铀尾矿坝稳定性分析的实例,可以准确形象的预测出坝潜在坡滑动面的位置和评价坝坡的稳定性,尤其对地形复杂的边坡稳定性分析简单适用。

  7. The effects of short-lived radionuclides and porosity on the early thermo-mechanical evolution of planetesimals

    Lichtenberg, Tim; Gerya, Taras V; Meyer, Michael R

    2016-01-01

    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 aluminum-26 and iron-60, 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-dif...

  8. On the modelling of steel thermo-mechanical and metallurgical behaviour. Application to welding and heat treatment process

    The aim of this research is the prediction of residual stresses and strains in submarine nuclear reactor vessels after a welding operation. In the first part, the author briefly describes the various welding processes, their thermal, metallurgical and mechanical consequences, and gives an overview of the state-of-the-art of computerized modelling of welding. Then, he gives a detailed description of the various proposed models of the thermo-mechanical and metallurgical behaviours of steels. The influence of different phenomena such as plasticity, visco-plasticity, and transformation induced plasticity on the mechanical behaviour of the blend is analysed according to a sequential approach: the behaviour of each metallurgical phase is elastoplastic with linear kinetic cold working, then elasto-viscoplastic. A combined model is presented in which the ferrite phase behaviour is elastoplastic and the austenite behaviour is elasto-viscoplastic. The proposed models are then validated by two computer simulations performed with the COMSOL Multiphysics code. These simulations are simulating two tests which are representative of the phenomena met during a welding operation

  9. Thermo-mechanical analysis for determining the optimum design of a deposition hole using FLAC3D

    In this study, the vertical location of canister in a deposition hole was determined from the thermo-mechanical coupling analysis using the three-dimensional finite difference code, FLAC3D. A FISH program was made and used for the modeling for different conditions. The following conclusions could be drawn from the study. (1) The canister moves downward initially, but moves upward with time due to the thermal expansion of buffer. (2) The tunnel floor above the deposition hole remains elastic until 100 years after the emplacement of the canister if the top buffer thickness is more than 1.5 m. (3) It was found that the peak temperature decreases with the increase of the buffer and backfill thickness, when backfilling is done immediately after the emplacement. (4) Without swelling pressure, the maximum tensile stress is up to 18 MPa at 100 days after the emplacement. Since the swelling pressure from the buffer confines the thermal expansion of the canister, the mechanical stability of canister is improved with the swelling pressure. (5) When the air temperature in the tunnels is maintained at 27 .deg. C by ventilation, the peak temperature with delayed backfilling for 50 years is about 75 .deg. while it is over 90 .deg. with immediately backfilling. (6) The buffer and backfill thickness above the canister in a deposition hole should be at least 2 m based on literature review and the computer simulations

  10. Thermomechanical room and canister region benchmark analyses between STEALTH-WI and SPECTROM-32: Draft final report

    This report documents the benchmarking of the two-dimensional waste isolation version of STEALTH (designated STEALTH-WI) against the thermomechanical performance assessment calculations performed by RE/SPEC using SPECTROM-32. An axisymmetric, canister-scale (very-near-field) analysis was performed to compute the peak stress exerted by the salt on the waste package. A plane strain, room-scale (near-field) analysis was also performed to predict disposal room roof-to-floor closure and the temperatures at key locations in the vicinity of the disposal room. Comparisons between the STEALTH and SPECTROM-32 results showed that the temperature predictions agreed to within 5/degree/C, peak canister stresses better than 10%, and the average roof-to-floor closures within 30%. The stress and displacement differences were attributed to differences in the treatment of plasticity in the constitutive laws for salt employed in STEALTH and SPECTROM-32. The temperature differences were due to minor differences in the thermal models employed in STEALTH and SPECTROM- 41, the thermal analysis code which supplies temperatures for SPECTROM-32. 9 refs., 21 figs., 6 tabs

  11. Aespoe Pillar Stability Experiment. Final coupled 3D thermo-mechanical modeling. Preliminary particle mechanical modeling

    SKB is planning to perform a large-scale pillar stability experiment called APSE (Aespoe Pillar Stability Experiment) at Aespoe HRL. The study is focused on understanding and control of progressive rock failure in hard crystalline rock and damage caused by high stresses. The elastic thermo-mechanical modeling was carried out in three dimensions because of the complex test geometry and in-situ stress tensor by using a finite-difference modeling software FLAC3D. Cracking and damage formation were modeled in the area of interest (pillar between two large scale holes) in two dimensions by using the Particle Flow Code (PFC), which is based on particle mechanics. FLAC and PFC were coupled to minimize the computer resources and the computing time. According to the modeling the initial temperature rises from 15 deg C to about 65 deg C in the pillar area during the heating period of 120 days. The rising temperature due to thermal expansion induces stresses in the pillar area and after 120 days heating the stresses have increased about 33% from the excavation induced maximum stress of 150 MPa to 200 MPa in the end of the heating period. The results from FLAC3D model showed that only regions where the crack initiation stress has exceeded were identified and they extended to about two meters down the hole wall. These could be considered the areas where damage may occur during the in-situ test. When the other hole is pressurized with a 0.8 MPa confining pressure it yields that 5 MPa more stress is needed to damage the rock than without confining pressure. This makes the damaged area in some degree smaller. High compressive stresses in addition to some tensile stresses might induce some AE (acoustic emission) activity in the upper part of the hole from the very beginning of the test and are thus potential areas where AE activities may be detected. Monitoring like acoustic emissions will be measured during the test execution. The 2D coupled PFC-FLAC modeling indicated that

  12. CANAL code

    The CANAL code presented here optimizes a realistic iron free extraction channel which has to provide a given transversal magnetic field law in the median plane: the current bars may be curved, have finite lengths and cooling ducts and move in a restricted transversal area; terminal connectors may be added, images of the bars in pole pieces may be included. A special option optimizes a real set of circular coils

  13. pMDI-Reinforced Compression-Molded PCL/Gluten: Thermomechanical Properties

    Polycaprolactone (PCL) and vital wheat gluten or wheat flour composites were prepared and compatibilized with polymeric diphenylmethane diisocyanate (pMDI) by blending and compression-molding. The thermo-mechanical properties of the composites were determined by thermogravimetric analysis (TGA), di...

  14. Analysis of physical process inter-relation in radioisotope thermo-mechanical generator

    Results of analysing thermal and energy processes in radioisotope thermomechanical generator (RTMG) with Stirling engine, obtained with the use of idealized physical model, are presented. Effect of external load on the formation of object thermal state and its output energy characteristics is considered. The reasons for a choice of optimal mode of RTMG operation, providing maximal efficiency of energy transformation are given

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

    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 Ni19.5Ti50.5Pd25Pt5 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)

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

    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.

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

    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....

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

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

    2014-12-01

    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 Ni19.5Ti50.5Pd25Pt5 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.

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

    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 resu

  20. FE MODEL OF THERMO-MECHANICAL INTERACTION IN RUBBER BLOCK UNDER DYNAMIC CYCLIC STRESS

    Pešek, Luděk; Šulc, Petr

    Praha: Humusoft s.r.o, 2006, s. 21-21. ISBN 80-239-8131-5. [COMSOMOL Conference Prague. Praha (CZ), 27.10.2006-27.10.2006] R&D Projects: GA ČR(CZ) GA101/05/2669 Institutional research plan: CEZ:AV0Z20760514 Keywords : rubber * dynamics * thermo-mechanical interaction Subject RIV: BI - Acoustics

  1. Prediction of the thermo-mechanical material behavior of PEN foil during photolithographic processing

    Barink, M.; Goorhuis, M.; Giesen P.; Furthner, F.; Yakimets, I.

    2009-01-01

    Flexible substrates (polymers) for plastic electronic products are far less stable to environmental factors, like heat and moisture, than currently used non-flexible substrates (silicon). This introduces problems during the lithography process of these products. This study presents a thermo-mechanic

  2. Application of ABAQUS Second-developed on Design of Flexible Risers%ABAQUS二次开发在海洋柔性立管设计分析中的应用

    孙丽萍; 周佳

    2011-01-01

    基于ABAQUS软件利用Python脚本语言和GUI功能开发了针对柔性立管的建模界面和求解模块.借此设计分析人员可以快速地建立柔性立管的有限元模型并进行计算分析,有效地解决了柔性立管在研制阶段的设计-分析-校核的重复繁琐问题,缩短了研发周期.%Using Python language and ABAQUS GUI Toolkit, the flexible riser simulation and calculation modular is developed. The program can make it simpler for the engineers to establish flexible riser model efficiently and to analyze whether it accords with its design requirements. The method can solve the trivial problem of the design-analysis-check during the design process and shorten the development period.

  3. Z-Pinch Power Plant Shock Mitigation Experiments, Modeling, and Code Assessment

    We are investigating attenuation techniques to mitigate the powerful shock that occurs inside the Z-Pinch Power Plant. For this purpose, we conducted a series of experiments at the University of Wisconsin. These experiments consisted of shock waves traveling at greater than Ma 1 that impacted aluminum foam under various configurations. In turn, ABAQUS, ALEGRA, CTH, and DYNA3D were used to simulate one of the experiments in order to validate the codes. Although the behavior of foamed solid and liquid metal is fundamentally different, we considered foamed metal because some disposable components of the ZP-3 (i.e. the RTL) may be designed with metal foam. In addition, the relatively simple experiments should help us determine which codes can better simulate shock waves. In the near future, we will conduct shock experiments using foamed materials such as water, oils, and other metals

  4. NOVEL BIPHASE CODE -INTEGRATED SIDELOBE SUPPRESSION CODE

    Wang Feixue; Ou Gang; Zhuang Zhaowen

    2004-01-01

    A kind of novel binary phase code named sidelobe suppression code is proposed in this paper. It is defined to be the code whose corresponding optimal sidelobe suppression filter outputs the minimum sidelobes. It is shown that there do exist sidelobe suppression codes better than the conventional optimal codes-Barker codes. For example, the sidelobe suppression code of length 11 with filter of length 39 has better sidelobe level up to 17dB than that of Barker code with the same code length and filter length.

  5. From concatenated codes to graph codes

    Justesen, Jørn; Høholdt, Tom

    2004-01-01

    We consider codes based on simple bipartite expander graphs. These codes may be seen as the first step leading from product type concatenated codes to more complex graph codes. We emphasize constructions of specific codes of realistic lengths, and study the details of decoding by message passing in...

  6. Concatenated codes with convolutional inner codes

    Justesen, Jørn; Thommesen, Christian; Zyablov, Viktor

    1988-01-01

    The minimum distance of concatenated codes with Reed-Solomon outer codes and convolutional inner codes is studied. For suitable combinations of parameters the minimum distance can be lower-bounded by the product of the minimum distances of the inner and outer codes. For a randomized ensemble of...... concatenated codes a lower bound of the Gilbert-Varshamov type is proved...

  7. Quantum Cyclic Code

    Dutta, Sagarmoy

    2010-01-01

    In this paper, we define and study \\emph{quantum cyclic codes}, a generalisation of cyclic codes to the quantum setting. Previously studied examples of quantum cyclic codes were all quantum codes obtained from classical cyclic codes via the CSS construction. However, the codes that we study are much more general. In particular, we construct cyclic stabiliser codes with parameters $[[5,1,3

  8. Development and explicit integration of a thermo-mechanical model for saturated clays

    This study is devoted to the thermo-mechanical constitutive modeling for saturated stiff clays and the development of a corresponding efficient stress integration algorithm. The mechanical behavior of natural Boom Clay in isothermal conditions was first characterized. The Modified Cam Clay model (MCC) was then applied to simulate the natural Boom Clay behavior. It has been found that the MCC gives poor-quality predictions of the natural Boom Clay behavior. Thereby, an adapted Cam Clay model (ACC-2) was developed by introducing a new yield surface and a new plastic potential as well as a Two-surface plastic mechanism. This model allows satisfactory prediction of the main features of the mechanical behavior of natural Boom Clay. Moreover, the constitutive equations of this model can be formulated mathematically as in a classic elasto-plastic model. Thus, the classic stress integration algorithm can be applied. The thermal effects were considered by assessing the performance of some advanced thermo-mechanical models (Cui et al., 2000; Abuel-Naga et al., 2007; Laloui and Francois, 2008; 2009). It appears that all the three models can capture the main features of the thermo-mechanical behavior of saturated clays. However, each constitutive model has its own limitations or unclear points from the theoretical point of view. The stress integration algorithm of the thermo-mechanical model proposed by Cui et al. (2000) at the stress point level was also developed using a specifically designed adaptive time-stepping scheme. The computation time required to achieve a given accuracy is largely reduced with the adaptive sub-stepping considered for both mechanical and thermal loadings. A two-surface thermo-mechanical model (TEAM model) was developed based on the two-surface plastic mechanism. The proposed model extends the model of Cui et al. (2000) to a two-surface formulation, considering the plastic strain coupling between the thermal and the mechanical loading paths. The

  9. Thermo-mechanical modelling of high energy particle beam impacts

    Scapin, M; Dallocchio, A

    2010-01-01

    The unprecedented energy intensities of modern hadron accelerators yield special problems with the materials that are placed close to or into the high intensity beams. The energy stored in LHC in a single beam is equivalent to about 80 kg of TNT explosive, stored in a transverse beam area of 0.2 mm×0.2 mm. The materials placed close to the beam are used at, or even beyond, their damage limits. However, it is very difficult to predict structural efficiency and robustness accurately: beam-induced damage occurs in a regime where practical experience does not exist. This study is performed in order to estimate the damage on a copper component due to the impact with a 7 TeV proton beam generated by LHC. The case study represents an accidental case consequent to an abnormal release of the beam, in which 8 bunches irradiate the target directly. The energy delivered on the component is calculated using the FLUKA code and then used as input in the numerical simulations, that are carried out via the FEM code LS-DYNA. ...

  10. The mechanism of thermomechanical training of a newly developed Fe-Mn-Si-Cr-Cu shape memory alloy

    Thermomechanical training was carried out on a newly developed Fe-20Mn-6Si-7Cr-1Cu shape memory alloy. It was observed that the effectiveness of thermomechanical training largely depends on the recovery annealing temperature and the pre-strain during training. Based on the analysis of the changes in critical stress for martensite formation, the critical stress for slip deformation, the phase transformation temperatures and microstructural development during training, it was concluded that the mechanism of thermomechanical training is based on the following two factors: (1) lowering of the critical stress for martensite formation, making stress induced γ→ε transformation easier; and (2) decreasing the Af temperature and refining the ε martensite structure, thus reducing the energy barrier for the ε→γ reverse transformation. The optimum thermomechanical training conditions have been determined for the alloy studied. (orig.)

  11. Stress Analysis on Complex Node of Overrun Structure Based on the Substructure Method by ABAQUS Software%基于ABAQUS子结构法对超限高层复杂节点的应力分析

    王雨生; 王曙光; 王滋军; 杜东升; 何静姿

    2012-01-01

    The force performance of the complex node in overrun high-rise structure is studied. Based on the substructure method of ABAQUS finite element software, the whole model and the fine model of the complex node are set up in one project. In the whole model, the fiber model is developed to beam-column elements, and the plastic damage model is used to shear wall. In the fine model of the complex node, the plastic damage model is used to solid elements, the metal double linear dynamic hardening model is used to steel and reinforcement. The complex nodes use two kinds of structure's form: steel reinforced concrete and steel tube's concrete. The displacement boundary conditions under the cases of small earthquakes, middle seismic and strong earthquakes of the complex node are exlraclcil from the whole model by the substructure method. It is the time to run the finite element analysis of the fine model of the complex node in ABAQUS and it will obtain the analysis result. The results show that the largest compressive strain of concrete has been more than standard limits under the strong earthquakes. Steel and reinforcement have already been in the inelastic phase, but not more than their limit strain, so the nodes are still in the secure stage. Which kind of node is more advantageous is quite clear through the analysis and comparison. This can provide some references for the design of the complex node in the overrun high-rise structure.%采用子结构方法研究超限高层建筑复杂节点的受力性能.基于ABAQUS有限元软件子结构方法,建立某超限高层的整体模型和复杂节点的精细模型,整体模型梁柱单元采用开发的纤维模型,剪力墙采用塑性损伤模型;复杂节点的精细模型中,实体单元采用混疑土塑性损伤模型,钢筋与型钢采用采用双线性动力硬化模型,该复杂节点采用两种结构形式:型钢混凝土结构和钢管混凝土结构.通过子结构方法提取整体模型中复杂节点处

  12. Kinetic Analysis of Anti-spin Thread Connection Elastic Roller Based on ABAQUS%基于ABAQUS反旋对接弹性滚子的动力学分析

    卢黎明; 秦豫江; 蔡颖

    2014-01-01

    This paper presents a new anti-spin thread connection elastic roller(ASTCER)that substitutes unidi-rectional helical elastic roller through structural design innovation with spring structure parameters. The finite element analysis model of ordinary cylindrical rollers,unidirectional spiral elastic rollers and anti-spin thread connection elastic rollers is established based on the ABAQUS. The axial displacement of their center of mass and the stress distribution of anti-spin thread connection elastic rollers are analyzed through their stress compari-son. Theoretical studies show that the new anti-spin thread connection elastic roller inherits some advantages of the unidirectional spiral elastic rollers and can avoid the axial offset of the single spiral elastic roller in motion and the huge wear in contact with the inner and outer rings.%借助弹簧结构参数以及结构设计创新,提出了一种替代单向螺旋弹性滚子的新型反旋对接弹性滚子。通过ABAQUS建立了普通圆柱滚子、单向螺旋弹性滚子及反旋对接弹性滚子的有限元分析模型,对比分析了它们的质心轴向位移及反旋对接弹性滚子对接面的应力分布情况。研究表明这种新型反旋对接弹性滚子能继承单向螺旋弹性滚子的主要优点,且能避免单旋向螺旋弹性滚子在运动中的轴向偏移及因此与内外圈挡边接触产生较大的磨损。

  13. Microstructure and Thermomechanical Properties of Shape Memory Alloys TI50-NI50 Elaborated by Arc Melting and by Powder Metallurgy

    Olier, P.; Brachet, J.; Guenin, G.

    1995-01-01

    This study was focussed on the elaboration and transformation of Ti50Ni50 shape memory alloys in relation to structural and thermomechanical properties. An original method for producing TiNi alloys by powder metallurgy (PM), through combustion synthesis, was developed. After hot extrusion, intermetallic rods without porosity were obtained. Microstructural and thermomechanical properties of products obtained by this method were systematically compared to those of some alloys elaborated by the ...

  14. The Mechanism of Thermomechanical Training of a Newly Developed Fe-Mn-Si-Cr-Cu Shape Memory Alloy

    Dunne, D.; Li, H.

    1995-01-01

    Thermomechanical training was carried out on a newly developed Fe-20Mn-6Si-7Cr-1Cu shape memory alloy. It was observed that the effectiveness of thermomechanical training largely depends on the recovery annealing temperature and the pre-strain during training. Based on the analysis of the changes in critical stress for martensite formation, the critical stress for slip deformation, the phase transformation temperatures and microstructural development during training, it was concluded that the...

  15. FEM 3D model of thermal processes of vibro-damping rubber elements with thermo-mechanical interaction

    Pešek, Luděk; Šulc, Petr

    Praha: Institute of Thermomechanics AS CR, v. v. i., 2007 - (Zolotarev, I.), s. 43-50 ISBN 978-80-87012-08-6. [Interaction and Feedbacks ´2007. Praha (CZ), 27.11.2007-28.11.2007] R&D Projects: GA ČR GA101/05/2669 Institutional research plan: CEZ:AV0Z20760514 Keywords : thermo-mechanics coupling * damping * dynamic loading Subject RIV: BI - Acoustics

  16. Quantum Convolutional BCH Codes

    Aly, S A; Klappenecker, A; Roetteler, M; Sarvepalli, P K; Aly, Salah A.; Grassl, Markus; Klappenecker, Andreas; Roetteler, Martin; Sarvepalli, Pradeep Kiran

    2007-01-01

    Quantum convolutional codes can be used to protect a sequence of qubits of arbitrary length against decoherence. We introduce two new families of quantum convolutional codes. Our construction is based on an algebraic method which allows to construct classical convolutional codes from block codes, in particular convolutional BCH codes. These codes have the property that they contain their Euclidean, respectively Hermitian, dual codes. Hence, they can be used to define quantum convolutional codes by the stabilizer code construction. We compute BCH-like bounds on the free distances which can be controlled as in the case of block codes, and establish that the codes have non-catastrophic encoders.

  17. The thermo-mechanics of the PWR fuel rod

    The fuel rod mechanics is of a great importance in the safety and performance of the reactors. In this domain a meeting has been organized by the SFEN the 18 march 1998 at Paris. With the participation of scientists from CEA, EDF and Framatome, the physics of the fuel rods was presented based on four main aspects. Two first papers dealt with the solicitations of the fuel rod in normal and accidental conditions. The physical phenomena under irradiation were then detailed in the four following talks. Three papers presented the simulation and the codes of the fuel-cladding interactions with the diabolo effect. The last paper was devoted to the experiment feedback and the research programs. (A.L.B.)

  18. The development and production of thermo-mechanically forged tool steel spur gears

    Bamberger, E. N.

    1973-01-01

    A development program to establish the feasibility and applicability of high energy rate forging procedures to tool steel spur gears was performed. Included in the study were relatively standard forging procedures as well as a thermo-mechanical process termed ausforming. The subject gear configuration utilized was essentially a standard spur gear having 28 teeth, a pitch diameter of 3.5 inches and a diametral pitch of 8. Initially it had been planned to use a high contact ratio gear design, however, a comprehensive evaluation indicated that severe forging problems would be encountered as a result of the extremely small teeth required by this type of design. The forging studies were successful in achieving gear blanks having integrally formed teeth using both standard and thermo-mechanical forging procedures.

  19. Effect of grain orientation on mechanical properties and thermomechanical response of Sn-based solder interconnects

    The thermomechanical response of Sn-based solder interconnects with differently oriented grains was investigated by electron backscattered diffraction technique under thermal cycling and thermal shock testing in this study. The results showed that deformation and cracking of solder interconnects have a close relationship with the unique characteristics of grain orientation and boundaries in each solder interconnect, and deformation was frequently confined within the high-angle grain boundaries. The micro Vickers hardness testing results showed that the hardness varied significantly depending on the grain orientation and structure, and deformation twins can be induced around the indents by the indentation testing. - Highlights: • Thermomechanical response shows a close relationship with the grain structure. • Deformation was frequently confined within the high-angle grain boundaries. • Different grain orientations exhibit different hardness. • Deformation twins can be induced around the indents in SAC105 solder interconnects

  20. Studies on the thermo-mechanical behavior of the CLIC two-beam module

    Nousiainen, R; Österberg, K

    2010-01-01

    To fulfil the mechanical requirements set by the luminosity goals of the CLIC collider, currently under study, the 2-m two-beam modules, the shortest repetitive elements in the main linac, have to be controlled at micrometer level. At the same time these modules are exposed to variable high power dissipation while the accelerator is ramped up to nominal power as well as when the mode of CLIC operation is varied. This will result into inevitable temperature excursions driving mechanical distortions in and between different module components. A FEM model is essential to estimate and simulate the fundamental thermo-mechanical behaviour of the CLIC two-beam module to facilitate its design and development. In this paper, the fundamental thermal environments for the RF-components of the module are described. Also the thermal and structural results for the studied module configuration are presented showing the fundamental thermo-mechanical behaviour under the main CLIC collider operation conditions.

  1. Properties of a Laminated Wood Composite Produced with Thermomechanically Treated Veneers

    Larissa M. Arruda

    2016-01-01

    Full Text Available The paper aimed at evaluating the properties of plywood made from thermomechanically treated wood veneers. Veneers from Amescla (Trattinnickia burseraefolia wood were treated in a hydraulic press with electric resistance heating. Two temperature levels were applied, 140°C and 180°C, for 1 and 2 minutes with 2.7 N/mm2 of pressure. A total of 30 plywood boards were produced, including six boards produced from untreated veneers. The results showed that the thermomechanical treatment did not have any deleterious effect on glue line strength and most of the mechanical properties of plywood made from treated veneers were improved. On the other hand, plywood made from untreated veneers presented better dimensional stability. Dimensional stability properties were most affected by the temperature of the treatment, while mechanical stability, represented by the glue line shear strength, was positively affected by temperature and duration of the treatment.

  2. Thermomechanical cycling tests of coated AISI 316L in Pb-17Li

    The permeation of tritium through the cooling pipes is one of the critical issues in the design of the Pb-17Li water-cooled blanket for the DEMO reactor. Aluminised coatings on the surfaces in contact with the Pb-17Li can significantly reduce the permeation rate through the steel and the tritium inventory in the blanket. A series of tests was conducted in order to verify the behaviour of these coatings in the presence of thermomechanical fatigue and in the Pb-17Li environment. The behaviour of the coatings, which sustained over one thousand thermal cycles in a temperature range of 260-320 C and were subjected to an additional mechanical stress of 100 MPa, was satisfactory. The aluminised surfaces were found to be compatible with the breeder and no appreciable embrittlement attributable to the thermomechanical cycling was noted. ((orig.))

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

    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. \

  4. Thermomechanical treatment and deformation behavior of iron based shape memory alloys

    The thermomechanical treatment (training) and deformation behavior of iron based shape memory alloys have been studied. The thermomechanical treatment results in improvement of shape memory effect. This improvement in shape memory effect can be attributed to the formation of lamellar structure of (lambda)/(epsilon) and to an increase in the volume fraction of epsilon martensite (epsilon). It is also found that excessive training may result in the nucleation of bcc martensite (alpha) along with epsilon martensite (epsilon) which degrades the shape memory effect. Also the shape memory effect decreases with the increase in amount of strain, which presumably can be regarded as the effect of increasing tendency of deformation to occur through slip and formation of (alpha) which reduces the reversibility of (epsilon) into (lambda). (author)

  5. Description of the performances of a thermo-mechanical energy harvester using bimetallic beams

    Arnaud, A.; Boughaleb, J.; Monfray, S.; Boeuf, F.; Cugat, O.; Skotnicki, T.

    2016-06-01

    Many recent researches have been focused on the development of thermal energy harvesters using thermo-mechanical or thermo-electrical coupling phenomena associated to a first-order thermodynamic transition. In the case of the bimetallic strip heat engine, the exploitation of the thermo-mechanical instability of bimetallic membranes placed in a thermal gradient enables to convert heat into kinetic energy. This paper is a contribution to the modeling and the comprehension of these heat engines. By restraining the study to the simply-supported bimetallic beams and using a Ritz approximation of the beam shape, this paper aims to give an analytical solution to the first mode of the composite beams and then to evaluate the efficiency of the harvesters exploiting these kinds of instability.

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

    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

  7. Thermo-mechanical pressurization of experimental faults in cohesive rocks during seismic slip

    Violay, M.; Di Toro, G.; Nielsen, S.; Spagnuolo, E.; Burg, J. P.

    2015-11-01

    Earthquakes occur because fault friction weakens with increasing slip and slip rates. Since the slipping zones of faults are often fluid-saturated, thermo-mechanical pressurization of pore fluids has been invoked as a mechanism responsible for frictional dynamic weakening, but experimental evidence is lacking. We performed friction experiments (normal stress 25 MPa, maximal slip-rate ∼3 ms-1) on cohesive basalt and marble under (1) room-humidity and (2) immersed in liquid water (drained and undrained) conditions. In both rock types and independently of the presence of fluids, up to 80% of frictional weakening was measured in the first 5 cm of slip. Modest pressurization-related weakening appears only at later stages of slip. Thermo-mechanical pressurization weakening of cohesive rocks can be negligible during earthquakes due to the triggering of more efficient fault lubrication mechanisms (flash heating, frictional melting, etc.).

  8. Heat generation and thermo-mechanical effect modeling in longitudinally diode-pumped solid state lasers

    Lakhdari, Fouad; Osmani, Ismahen; Tabet, Saida

    2015-09-01

    Thermal management in solid state laser is a challenge to the high power laser industry's ability to provide continued improvements in device and system performance. In this work an investigation of heat generation and thermo-mechanical effect in a high-power Nd:YAG and Yb:YAG cylindrical-type solid state laser pumped longitudinally with different power by fibre coupled laser diode is carried out by numerical simulation based on the finite element method (FEM). Impact of the dopant concentration on the power conversion efficiency is included in the simulation. The distribution of the temperature inside the lasing material is resolute according to the thermal conductivity. The thermo-mechanical effect is explored as a function of pump power in order to determine the maximum pumping power allowed to prevent the crystal's fracture. The presented simulations are in broad agreement with analytical solutions; provided that the boundary condition of the pump induced heat generation is accurately modelled.

  9. Concatenated Conjugate Codes

    Hamada, M

    2006-01-01

    A conjugate code pair is defined as a pair of linear codes either of which contains the dual of the other. A conjugate code pair represents the essential structure of the corresponding Calderbank-Shor-Steane (CSS) quantum code. It is known that conjugate code pairs are applicable to (quantum) cryptography. We give a construction method for efficiently decodable conjugate code pairs.

  10. Fundamentals of convolutional coding

    Johannesson, Rolf

    2015-01-01

    Fundamentals of Convolutional Coding, Second Edition, regarded as a bible of convolutional coding brings you a clear and comprehensive discussion of the basic principles of this field * Two new chapters on low-density parity-check (LDPC) convolutional codes and iterative coding * Viterbi, BCJR, BEAST, list, and sequential decoding of convolutional codes * Distance properties of convolutional codes * Includes a downloadable solutions manual

  11. Molecular dynamics simulations and experimental studies of the thermomechanical response of an epoxy thermoset polymer

    Li, Chunyu; Medvedev, Grigori A.; Lee, Eun-Woong; Kim, JaeWoo; Caruthers, James M.; Strachan, Alejandro

    2012-01-01

    We report a detailed comparison between molecular dynamics predictions and experimental results for a wide range of thermo-mechanical properties of an epoxy resin system: diglycidyl ether of bisphenol A (DGEBA) cured with 3,3' diamino-diphenyl sulfone (33DDS). A set of carefully designed and characterized experiments provides validation data for the simulations that predict the molecular structure and properties of the thermoset. Our results show that current state-of-the-art molecular dynami...

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

    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 − R0/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

  13. Thermal and thermomechanical behaviour of polycaprolactone and starch/polycaprolactone blends for biomedical applications

    Wang, Y.; Rodriguez-Perez, M. A.; Reis, R. L.; Mano, J.F

    2005-01-01

    Polycaprolactone (PCL) and starch/PCL blends (SPCL) are shown to have the potential to be used in a range of biomedical applications and can be processed with conventional melting-based procedures. In this paper, the thermal and thermomechanical analyses of PCL and SPCL were performed, using DSC, optical microscopy and DMA. Starch effectively increased the non-isothermal crystallisation rate of PCL. Non-isothermal crystallisation kinetics was analyzed using Ozawa model, and a method, which co...

  14. Microstructure evolution of high-manganese steel during the thermomechanical processing

    L.A. Dobrzański; A. Grajcar; W. Borek

    2009-01-01

    Purpose: The aim of the paper is to determine the influence of hot-working conditions on microstructure evolution of new-developed high-manganese austenitic steel.Design/methodology/approach: The hot-working behaviour was determined in continuous and multi-stage compression tests performed in a temperature range of 850 to 1100°C by the use of the Gleeble 3800 thermomechanical simulator. The processes controlling work hardening and removing it were identified by microstructure evolution observ...

  15. Application of thermo-mechanically treated drill cuttings as an alternative to bentonite in spud muds

    Taghiyev, Farid

    2014-01-01

    Drill cuttings recovered after drilling with OBM today are treated and deposited at onshore facilities. The TWMA Company offers a new technology, which recovers drilled subsurface materials together with oil and water rests. Due to the similarity between subsurface rock mineralogy and conventional bentonite used in the drilling fluid industry an extended laboratory study was carried out to evaluate the possibility of spud mud development using thermo-mechanically treated drill cuttings. Pr...

  16. Effect of Composition and Thermomechanical Processingon The Intergranular Corrosion of AA6000 Aluminium Alloys

    Larsen, Magnus Hurlen

    2010-01-01

    In order to achieve the desired strength, AlMgSi (6000-series) alloys are often alloyed with either small (fraction of a wt%) Cu or excess (in relation to that required to form Mg2Si) amounts of Si. Both approaches can introduce the desired strength after artificial ageing. However, these methods have also been reported to introduce susceptibility to intergranular corrosion (IGC), depending on the applied thermomechanical treatment procedure. There is disagreement in the literature whether ad...

  17. Segregation of alloying elements in thermomechanically rolled medium-Mn multiphase steels

    A. Grajcar

    2012-12-01

    Full Text Available Purpose: The aim of the paper is to assess the tendency of alloying elements to macro- and microsegregation during hot-forging and successive thermomechanical rolling of medium-Mn Al-bearing steel sheets.Design/methodology/approach: The macro- and microsegregation of alloying elements was assessed by EDS and WDS measurements across the thickness of the roughly-forged flats and thermomechanically processed 3.3 mm sheets. The microstructure was revealed using combined methods of optical microscopy (OM and scanning electron microscopy (SEM. Morphological features of microstructural constituents were discussed with focusing on retained austenite. Findings: It was found that the final multiphase microstructure is mainly dependent on the Mn content and the effect of Nb microaddition is relatively low. The 3Mn steels possess very fine bainite-based microstructures whereas the steels containing 5% Mn are characterized by lath bainitic-martensitic microstructures. All the steels contain retained austenite as fine granules or layers located between bainitic ferrite laths. Some fraction of martensite-austenite (M-A islands was also identified. The tendency of Mn and Al to macrosegregation was found after the initial hot-forging. It disappears after successive rough and thermomechanical rolling whereas thin martensite and martensite-austenite microbands as a result of Mn microsegregation locally occur.Research limitations/implications: Further investigations are required to quantify the local changes of chemical composition especially in formed microbands and X-ray quantitative phase analysis should be applied to assess a fraction of retained austenite.Practical implications: The knowledge of the macro- and microsegregation of alloying elements in advanced medium-Mn steels containing retained austenite can be useful in designing the thermomechanical rolling procedures of multiphase steel sheets.Originality/value: A problem of macro- and microsegregation of

  18. Axisymmetric thermo-mechanical analysis of laser-driven noncontact transfer printing

    Huang, Yonggang

    2014-01-01

    An axisymmetric thermo-mechanical model is developed for laser-driven noncontact transfer printing, which involves laser-induced impulsive heating to initiate separation at the interface between a soft, elastomeric stamp, and hard micro/nanomaterials (i.e., inks) on its surface due to a large mismatch in coefficients of thermal expansion. The result is the active ejection of the inks from the stamp, to a spatially separated receiving substrate, thereby representing the printing step. The mode...

  19. Nonlinear thermomechanical deformation behaviour of P-FGM shallow spherical shell panel

    Vishesh Ranjan Kar; Subrata Kumar Panda

    2016-01-01

    In the present article, the linear and the nonlinear deformation behaviour of functionally graded (FG) spherical shell panel are examined under thermomechanical load. The temperature-dependent effective material properties of FG shell panel are evaluated using Voigt’s micro-mechanical rule in conjunction with power-law distribution. The nonlinear mathematical model of the FG shell panel is developed based on higher-order shear deformation theory and Green-Lagrange type geometrical nonlinearit...

  20. Optimatization of thermomechanical processing of Si-Mn TRIP steel by using in situ neutron diffraction

    Lukáš, Petr; Jenčuš, Peter; Zrník, J.; Nový, Z.

    Geneve , 2003. s. -. [Proceedings of the Internacional Conference of Mechanical Behaviour of Materials /9./. 25.05.2003-29.05.2003, Geneve ] R&D Projects: GA AV ČR IAA1048107; GA ČR GA202/03/0891; GA AV ČR KSK1010104 Keywords : neutron diffraction * thermomechanical prosessing of Si-Mn Subject RIV: BM - Solid Matter Physics ; Magnetism

  1. A thermomechanical criterion for hot cracking during electron beam welding of CuCrZr alloy

    Full text of publication follows: Due to its good thermomechanical and thermophysical properties, precipitation hardened CuCrZr alloy is used for structural components in fusion experiments such as Tore Supra, JET, W7X and will find also application in the thermonuclear fusion reactor ITER. In Tore Supra (CEA Cadarache, France) this material is typically used for heat sink structures of plasma facing components. The experience feedback showed that the CuCrZr alloy was very sensitive to the hot tearing phenomenon during electron beam welding, leading to defects in and/or near the melted zone. The objective of the project under consideration is to propose a hot tearing criterion by mean of numerical simulations, in order to define a welding acceptance test which could be applied to the material, delivered from different manufacturers. In order to characterize the hot tearing phenomenon, a laboratory test, inspired by the Shibahara's experiment, is used. An electron beam welding seam is performed on a thin rectangular plate, which is instrumented with thermocouples while a CCD camera allows recording of eventual cracking defects during welding. The image correlation method permits to determine the displacement field in the solidified welding seam as well as in the non melted zone. In order to identify the hot tearing criterion due to the welding process, the stress and strain state in the material during the laboratory test is calculated with a Lagrangian thermomechanical finite element simulation. For high temperatures, the alloy viscosity is taken into account in order to identify an elasto-viscoplastic behaviour law. Thermomechanical experiments are performed with a Gleeble physical simulator. A thermomechanical criterion for the initiation of hot tearing during electron beam welding of a quenched and aged CuCr1Zr alloy (DIN 17672 standard) has been identified. (authors)

  2. Test program element II blanket and shield thermal-hydraulic and thermomechanical testing, experimental facility survey

    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.

  3. Space cryogenics components based on the thermomechanical effect - Vapor-liquid phase separation

    Yuan, S. W. K.; Frederking, T. H. K.

    1989-01-01

    Applications of the thermomechanical effect has been qualified including incorporation in large-scale space systems in the area of vapor-liquid phase separation (VLPS). The theory of the porous-plug phase separator is developed for the limit of a high thermal impedance of the solid-state grains. Extensions of the theory of nonlinear turbulent flow are presented based on experimental results.

  4. Thermo-mechanical Response and Damping Behavior of Shape Memory Alloy-MAX Phase Composites

    Kothalkar, Ankush Dilip; Benitez, Rogelio; Hu, Liangfa; Radovic, Miladin; Karaman, Ibrahim

    2014-05-01

    NiTi/Ti3SiC2 interpenetrating composites that combine two unique material systems—a shape memory alloy (SMA) and a MAX phase—demonstrating two different pseudoelastic mechanisms, were processed using spark plasma sintering. The goal of mixing these two material systems was to enhance the damping behavior and thermo-mechanical response of the composite by combining two pseudoelastic mechanisms, i.e., reversible stress-induced martensitic transformation in SMA and reversible incipient kink band formation in MAX phase. Equal volume fractions of equiatomic NiTi and Ti3SiC2 were used. Microstructural characterization was conducted using scanning electron microscopy to study the distribution of NiTi, Ti3SiC2, and remnant porosity in the composite. Thermo-mechanical testing in the form of thermal cycles under constant stress levels was performed in order to characterize shape memory behavior and thereby introducing residual stresses in the composites. Evolution of two-way shape memory effect was studied and related to the presence of residual stresses in the composites. Damping behavior, implying the energy dissipation per loading-unloading cycle under increasing compressive stresses, of pure NiTi, pure Ti3SiC2, as-sintered, and thermo-mechanically cycled (TC) NiTi/Ti3SiC2 composites, was investigated and compared to the literature data. In this study, the highest energy dissipation was observed for the TC composite followed by the as-sintered (AS) composite, pure NiTi, and pure Ti3SiC2 when compared at the same applied stress levels. Both the AS and TC composites showed higher damping up to 200 MPa stress than any of the metal—MAX phase composites reported in the literature to date. The ability to enhance the performance of the composite by controlling the thermo-mechanical loading paths was further discussed.

  5. Inversion of geothermal heat flux in a thermomechanically coupled nonlinear Stokes ice sheet model

    Zhu, Hongyu; Petra, Noemi; Stadler, Georg; Isaac, Tobin; Hughes, Thomas J. R.; Ghattas, Omar

    2016-01-01

    We address the inverse problem of inferring the basal geothermal heat flux from surface velocity observations using a steady-state thermomechanically coupled nonlinear Stokes ice flow model. This is a challenging inverse problem since the map from basal heat flux to surface velocity observables is indirect: the heat flux is a boundary condition for the thermal advection–diffusion equation, which couples to the nonlinear Stokes ice flow equations; together they determin...

  6. Influence of vibrational treatment on thermomechanical response of material under conditions identical to friction stir welding

    Konovalenko, Ivan S., E-mail: ivkon@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Konovalenko, Igor S., E-mail: igkon@ispms.tsc.ru; Kolubaev, Evgeniy A., E-mail: eak@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Dmitriev, Andrey I., E-mail: dmitr@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Psakhie, Sergey G., E-mail: sp@ms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    A molecular dynamics model was constructed to describe material loading on the atomic scale by the mode identical to friction stir welding. It was shown that additional vibration applied to the tool during the loading mode provides specified intensity values and continuous thermomechanical action during welding. An increase in additional vibration intensity causes an increase both in the force acting on the workpiece from the rotating tool and in temperature within the welded area.

  7. Evaluation the thermomechanics behavior the nuclear fuel to the design the Juragua Nuclear Power Plant

    In the work proposed a methodology to analyze the integral evaluation the thermomechanics behavior the nuclear fuel to the VVER 440 type reactors. They are presented some studies the sensibility and the obtained results for the first seven cycles the design to the Juragua Nuclear Power Plant, considering the tolerances gives fabrication the the nuclear fuel and the operation conditions the reactor to power and overpotential work

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

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

    2014-01-01

    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...... showing the most sensitive constitutive parameters that contribute to the uncertainty. This analysis provides the contribution of each parameter establishing the accuracy of the constitutive equations....

  9. Thermomechanical cycling investigation of CU particulate and NITI reinforced lead-free solder

    Horton, W. Scott.

    2006-01-01

    In todayâ s Flip Chip (FC) and Ball Grid Array (BGA) electronic packages solder joints provide both the electrical as well as the mechanical connections between the silicon chip and the substrate. Due to coefficient of thermal expansion (CTE) differences between the chip and substrate the solder joints undergo thermomechanical stresses and strains as an electronic package is heated and cooled with power on/off cycles. Advances in chip designs result in chips that are larger, run hotter and d...

  10. Numerical modeling of the thermomechanical behavior of steels with allowance for the propagation of Luders bands

    Balokhonov, R. R.; Romanova, V. A.

    2007-09-01

    A thermomechanical model based on physical representations of the motion of dislocation continuum and a model for the initiation and propagation of plastic shear are proposed to describe slow flows of the type of Luders bands. Two-dimensional calculations of Luders band propagation are performed for HSLA-65 steel samples under compression at various strain rates and temperatures. The calculation results are in good agreement with experimental data.

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

    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.

  12. Identification of thermo-mechanical parameters of concrete samples from nuclear plant

    Zatloukal, J.; Fonůsek, J.; Bezdička, Petr; Gajdoš, M.

    Vol. 675-676. Switzerland: Trans Tech Publications, 2016, s. 749-755. ISSN 1662-9795. [International Conference on Applied Physics and Material Applications, ICAPMA 2015 /2./. Pattaya (TH), 28.05.2015-30.05.2015] Institutional support: RVO:61388980 Keywords : Civil structures of nuclear plants * TG/DTA * Thermo-mechanical properties Subject RIV: CA - Inorganic Chemistry http://www.scientific.net/KEM.675-676.749

  13. Test program element II blanket and shield thermal-hydraulic and thermomechanical testing, experimental facility survey

    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

  14. A thermo-mechanical stress prediction model for contemporary planar sodium sulfur (NaS) cells

    Jung, Keeyoung; Colker, Jeffrey P.; Cao, Yuzhe; Kim, Goun; Park, Yoon-Cheol; Kim, Chang-Soo

    2016-08-01

    We introduce a comprehensive finite-element analysis (FEA) computational model to accurately predict the thermo-mechanical stresses at heterogeneous joints and components of large-size sodium sulfur (NaS) cells during thermal cycling. Quantification of the thermo-mechanical stress is important because the accumulation of stress during cell assembly and/or operation is one of the critical issues in developing practical planar NaS cells. The computational model is developed based on relevant experimental assembly and operation conditions to predict the detailed stress field of a state-of-the-art planar NaS cell. Prior to the freeze-and-thaw thermal cycle simulation, residual stresses generated from the actual high temperature cell assembly procedures are calculated and implemented into the subsequent model. The calculation results show that large stresses are developed on the outer surface of the insulating header and the solid electrolyte, where component fracture is frequently observed in the experimental cell fabrication process. The impacts of the coefficients of thermal expansion (CTE) of glass materials and the thicknesses of cell container on the stress accumulation are also evaluated to improve the cell manufacturing procedure and to guide the material choices for enhanced thermo-mechanical stability of large-size NaS cells.

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

    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.

  16. Anisotropic thermo-mechanical damage modelling for cementitious materials at high temperature

    The behavior of concrete at elevated temperatures is important for an assessment of integrity (strength and durability) of structures exposed to high temperature environment, in application such as fire exposure, smelting plants, nuclear installations. This paper we develop numerical algorithms for the integration of a thermo-mechanical damage model for concrete at high temperature. The model has been derived within the consistent framework of thermodynamics, drawing on the iso-thermal damage of Ortiz and Yazdani and Schreyer and the thermo-mechanical coupling aspects of Simo and Miehe. In addition, account has been taken of the known stress-temperature dependence of concrete through the descriptions of thermal and thermo-mechanical damage, and the thermal softening. Mechanical damage is related directly to compliance, with additional flexibility due to thermal damage. Explicit expressions have been derived for the free energy including elastic energy, damage due to micro-crack formation, thermal-mechanical coupling and thermal energy. The damage function is shown to be flexible in being able to capture the temperature dependent shape and size of failure surfaces: the model generally incorporates features of anisotropic damage, dilatation and inelastic strain responses. In a wider context, the damage model presented forms part of a study aimed at the development of a completely generalized analysis of concrete at transient elevated temperatures, including the coupling of damage, hygral diffusion and heat conduction through the material. Refs. 4 (author)

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

    Han Yuanfei [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Zeng Weidong, E-mail: zengwd@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Qi Yunlian; Zhao Yongqing [Northwest Institute for Nonferrous Metal Research, Xi' an 710016 (China)

    2011-11-15

    Highlights: {yields} Temperature and strain rate have great influence on the microstructure features. {yields} The formation of sub-grain and dislocation wall is the typically microstructure features observed in the {beta} single-phase. {yields} The elongated lamellar {alpha} platelets kinked increasingly and break up under the {alpha} + {beta} processing conditions. {yields} 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{sup -1}. During the isothermal compression experiment, the flow stress-strain curves are examined in the {beta} single-phase and in the {alpha} + {beta} 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 {alpha} 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-{alpha} titanium alloy.

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

    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.

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

    Vasiliev, N.N.; Sokolov, Yu.A.; Shatalov, G.E. [and others

    1995-09-01

    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 Beryllium{close_quotes} for succeeding thermomechanical testing. Two of them were manufactured in accordance with JET team design; they are round {open_quotes}hypervapotron type{close_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 tube{close_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 tube{close_quotes} type are given in this report.

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

    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

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

    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)

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

    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.

  3. Thermo-mechanical study of bare 48Y UF6 containers exposed to the regulatory fire environment

    Most of the regulatory agencies world-wide require that containers used for the transportation of natural UF6 and depleted UF6 must survive a fully-engulfing fire environment for 30 minutes as described in 10CFR71 and in TS-R-1. The primary objective of this project is to examine the thermo-mechanical performance of 48Y transportation cylinders when exposed to the regulatory hypothetical fire environment without the thermal protection that is currently used for shipments in those countries where required. Several studies have been performed in which UF6 cylinders have been analyzed to determine if the thermal protection currently used on UF6 cylinders of type 48Y is necessary for transport. However, none of them could clearly confirm neither the survival nor the failure of the 48Y cylinder when exposed to the regulatory fire environment without the additional thermal protection. A consortium of five companies that move UF6 is interested in determining if 48Y cylinders can be shipped without the thermal protection that is currently used. Sandia National Laboratories has outlined a comprehensive testing and analysis project to determine if these shipping cylinders are capable of withstanding the regulatory thermal environment without additional thermal protection. Sandia-developed coupled physics codes will be used for the analyses that are planned. A series of destructive and non-destructive tests will be performed to acquire the necessary material and behavior information to benchmark the models and to answer the question about the ability of these containers to survive the fire environment. Both the testing and the analysis phases of this project will consider the state of UF6 under thermal and pressure loads as well as the weakening of the steel container due to the thermal load. Experiments with UF6 are also planned to collect temperature- and pressure-dependent thermophysical properties of this material.

  4. The CATHARE code strategy and assessment

    The French thermal-hydraulic code CATHARE is being developed in Grenoble by EDF, FRAMATOME and CEA. The best-estimate objectives of CATHARE require a very rigorous methodology for development and assessment. In particular, the validation process is performed in two steps: Qualification of the models against separate effect tests and verification of the code on integral loop tests. The validation reports and the resulting evaluation document and user guidelines manual are delivered to the users. This paper illustrates the methodology for the case of CATHARE 1 version 1.3. The qualification process was conducted with reference to a matrix of 300 tests selected from experiments on critical flow, flow pattern determination, blowdown of heated or adiabatic test sections in various geometries, reflooding, boil-off, steam generator and pump behaviour, fuel thermomechanics. The results show the adequacy and the consistency of the models but indicate some items to be further studied: Droplet diameter correlation, incipience of boiling model, critical flow in diaphragms, top-down rewet or reflood, interphase friction in rod bundle geometry. The verification process was performed on 21 tests coming from LOBI, LOFT, LSTF, PKL facilities. The natural circulation post-test calculations show good results for single phase or two-phase mass flowrate evaluation and a satisfactory prediction of the reflux condensor phase. The various phases of the small break or large break transients are generally well described by CATHARE. (orig./GL)

  5. Twisted Permutation Codes

    Gillespie, Neil I.; Praeger, Cheryl E.; Spiga, Pablo

    2014-01-01

    We introduce twisted permutation codes, which are frequency permutation arrays analogous to repetition permutation codes, namely, codes obtained from the repetition construction applied to a permutation code. In particular, we show that a lower bound for the minimum distance of a twisted permutation code is the minimum distance of a repetition permutation code. We give examples where this bound is tight, but more importantly, we give examples of twisted permutation codes with minimum distance...

  6. Transitive nonpropelinear perfect codes

    Mogilnykh, I. Yu.; Solov'eva, F. I.

    2014-01-01

    A code is called transitive if its automorphism group (the isometry group) of the code acts transitively on its codewords. If there is a subgroup of the automorphism group acting regularly on the code, the code is called propelinear. Using Magma software package we establish that among 201 equivalence classes of transitive perfect codes of length 15 from \\cite{ost} there is a unique nonpropelinear code. We solve the existence problem for transitive nonpropelinear perfect codes for any admissi...

  7. Thermomechanical meso-scale modeling of combustion of heterogeneous solid propellants

    Srinivasan, Karthik Ram

    This dissertation is concerned with the development of robust numerical techniques to simulate the combustion of deformable heterogeneous solid propellants. While state of the art numerical models tend to consider the propellant as rigid, recent experiments have shown that the thermomechanical deformations and subsequent damage play a vital role in the initiation of deflagration-to-detonation transitions. It is therefore imperative that numerical models for combustion of heterogeneous solid propellants incorporate effects of thermomechanical deformation. Significant challenges in this type of modeling arise from (a) the nearly-incompressible behavior of the binder; (b) the high mismatch in moduli of the constituents; (c) a high loading of oxidizer particles; (d) the large thermomechanical deformations; (e) a propagating non-planar propellant surface and (f) the complex fluid-phase chemical reactions. This dissertation describes the development of a numerical framework that addresses these challenges. In the first part of this dissertation, an extension of the generalized finite element method to the class of mixed finite element methods is presented and two formulations, one based on a continuous deformation map and the other on a discontinuous one, for modeling material interfaces are investigated. A bimaterial patch test is formulated to assess the ability of the two formulations to reproduce constant stress fields, while a mesh convergence study is used to examine the consistency of the formulations. Finally, compression of a model heterogeneous propellant pack is simulated to demonstrate the robustness of the discontinous deformation map formulation. In the second part of this dissertation, a numerical framework based on the discontinuous deformation method is developed to capture the coupled effects of thermomechanical deformations and thermal gradients on the regression rate of the heterogeneous solid propellant, where propellant regression is simulated using

  8. Homological stabilizer codes

    In this paper we define homological stabilizer codes on qubits which encompass codes such as Kitaev’s toric code and the topological color codes. These codes are defined solely by the graphs they reside on. This feature allows us to use properties of topological graph theory to determine the graphs which are suitable as homological stabilizer codes. We then show that all toric codes are equivalent to homological stabilizer codes on 4-valent graphs. We show that the topological color codes and toric codes correspond to two distinct classes of graphs. We define the notion of label set equivalencies and show that under a small set of constraints the only homological stabilizer codes without local logical operators are equivalent to Kitaev’s toric code or to the topological color codes. - Highlights: ► We show that Kitaev’s toric codes are equivalent to homological stabilizer codes on 4-valent graphs. ► We show that toric codes and color codes correspond to homological stabilizer codes on distinct graphs. ► We find and classify all 2D homological stabilizer codes. ► We find optimal codes among the homological stabilizer codes.

  9. Global sensitivity analysis of thermomechanical models in modelling of welding

    Current approach of most welding modellers is to content themselves with available material data, and to chose a mechanical model that seems to be appropriate. Among inputs, those controlling the material properties are one of the key problems of welding simulation: material data are never characterized over a sufficiently wide temperature range. This way to proceed neglect the influence of the uncertainty of input data on the result given by the computer code. In this case, how to assess the credibility of prediction? This thesis represents a step in the direction of implementing an innovative approach in welding simulation in order to bring answers to this question, with an illustration on some concretes welding cases.The global sensitivity analysis is chosen to determine which material properties are the most sensitive in a numerical welding simulation and in which range of temperature. Using this methodology require some developments to sample and explore the input space covering welding of different steel materials. Finally, input data have been divided in two groups according to their influence on the output of the model (residual stress or distortion). In this work, complete methodology of the global sensitivity analysis has been successfully applied to welding simulation and lead to reduce the input space to the only important variables. Sensitivity analysis has provided answers to what can be considered as one of the probable frequently asked questions regarding welding simulation: for a given material which properties must be measured with a good accuracy and which ones can be simply extrapolated or taken from a similar material? (author)

  10. Model Children's Code.

    New Mexico Univ., Albuquerque. American Indian Law Center.

    The Model Children's Code was developed to provide a legally correct model code that American Indian tribes can use to enact children's codes that fulfill their legal, cultural and economic needs. Code sections cover the court system, jurisdiction, juvenile offender procedures, minor-in-need-of-care, and termination. Almost every Code section is…

  11. Approach to the calculation of energy deposition in a container of fuel irradiated by the neutronic codes coupling fluid-dynamics; Aprpoximacion al calculo de la deposicion energetica en un contenedor de combustible irradiado mediante el acoplamiento de codigos neutronico fluido-dinamicos

    Hueso, C.; Aleman, A.; Colomer, C.; Fabbri, M.; Martin, M.; Saellas, J.

    2013-07-01

    In this work identifies a possible area of improvement through the creation of a code of coupling between deposition energy codes which calculate neutron (MCNP), and data from heading into fluid dynamics (ANSYS-Fluent) or codes thermomechanical, called MAFACS (Monte Carlo ANSYS Fluent Automatic Coupling Software), being possible to so summarize the process by shortening the needs of computing time, increasing the precision of the results and therefore improving the design of the components.

  12. Turbo Codes Extended with Outer BCH Code

    Andersen, Jakob Dahl

    1996-01-01

    The "error floor" observed in several simulations with the turbo codes is verified by calculation of an upper bound to the bit error rate for the ensemble of all interleavers. Also an easy way to calculate the weight enumerator used in this bound is presented. An extended coding scheme is proposed...... including an outer BCH code correcting a few bit errors....

  13. The SCANAIR code version 3.2: Main features and status of qualification

    The SCANAIR code is developed in order to describe the thermo-mechanical behavior of highly irradiated PWR fuel rods under Reactivity-Initiated Accident (RIA). The main features of the newly delivered version of the code (version 3.2) are presented. Zircaloy-4 cladding mechanical properties have been updated with the results of tests performed in the frame of the PROMETRA program. Fuel-cladding gap thermal conductance modeling, and its behavior at high temperature and large contact pressure, is presented. Current features of the fission gas behavior modeling are described. Then, the status of the physical qualification of the code is given, and focuses on the cladding-related mechanical behavior (cladding hoop strain and transient elongation), and on the fission gas release. Finally, the planned evolution of the code is outlined. (author)

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

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

    Highlights: ► Ultrafine bainite + martensite duplex microstructure developed in SAE 52100 steel. ► Thermomechanical processing modifies size + morphology of bainitic ferrite. ► Processing involves hot deformation prior to/during/after austenitizing. ► Significant improvement in mechanical strength achieved. ► 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 °C for 15 min followed by austempering at 270 °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.

  16. DART code optimization works

    DART (Dispersion Analysis Research Tool) calculation and assessment program is a thermomechanical computer model developed by Dr. J. Rest of Argonne National Laboratory, USA. This program is the only mechanistic model available to assure the performance of low-enriched oxided-based dispersion fuels, dispersion of siliciures and uranium intermetallics in aluminum matrix for research reactors. The program predicts fission-products induced swelling (especially gases), fuel behavior during fabrication porosity closing, macroscopical changes in diameter of rods or width of plates and tubes produced by fuel deformation, degradation of thermal conductivity of fuel dispersion owing to irradiation and fuel restructuring because of Al-fuel reaction, amorphization and recrystallization. (author)

  17. Affine Grassmann codes

    Høholdt, Tom; Beelen, Peter; Ghorpade, Sudhir Ramakant

    2010-01-01

    We consider a new class of linear codes, called affine Grassmann codes. These can be viewed as a variant of generalized Reed-Muller codes and are closely related to Grassmann codes.We determine the length, dimension, and the minimum distance of any affine Grassmann code. Moreover, we show that...... affine Grassmann codes have a large automorphism group and determine the number of minimum weight codewords....

  18. Rateless feedback codes

    Sørensen, Jesper Hemming; Koike-Akino, Toshiaki; Orlik, Philip

    2012-01-01

    This paper proposes a concept called rateless feedback coding. We redesign the existing LT and Raptor codes, by introducing new degree distributions for the case when a few feedback opportunities are available. We show that incorporating feedback to LT codes can significantly decrease both the...... coding overhead and the encoding/decoding complexity. Moreover, we show that, at the price of a slight increase in the coding overhead, linear complexity is achieved with Raptor feedback coding....

  19. High burnup in DIONISIO code

    with high precision the neutron flux, burnup and concentration of every isotope, fissile, fissionable or fertile, gaseous or solid, all of them as functions of radius and time. But this formidable task is not suitable to be included in a fuel performance code, which must attend the great number of thermomechanical and thermochemical processes within the fuel rod. To accommodate both requirements, a simplified treatment is adopted consisting of restricting the balance equations to more relevant nuclides and reducing the energy spectrum to a single group. The purpose is to obtain empirical expressions to represent, with the higher possible approximation degree, the absorption, capture and fission cross sections of these isotopes as functions of the initial enrichment in 235U, the average burnup and the radial coordinate. The curves obtained with a so drastic simplification demand a careful testing before incorporation in the general fuel behaviour code. This testing is performed via comparison with the reliable reactor codes. The first antecedent in this type of analysis is found in the RADAR model [4] which was validated against the WIMS [5,6] code. The TUBRNP model, included in the TRANSURANUS code [7] and the RAPID model [8] are also based on the same concept. In this work curves fitted for the cross sections of 235U, 236U, 238U, 239Pu, 240Pu, 241Pu and 242Pu are obtained from the predictions of the reactor cell codes HUEMUL [9] and CONDOR [10] for an average burnup ranging from fresh fuel to 120 MWd/kgHM and for an initial enrichment ranging from natural uranium to 12%. The final purpose is to extend the application range of the DIONISIO code [11,12,13] (originally designed to predict the fuel behavior in normal operation conditions) to the high burnup domain. The predictions of DIONISIO were compared with a large number of experimental data, obtaining an excellent agreement

  20. Advanced video coding systems

    Gao, Wen

    2015-01-01

    This comprehensive and accessible text/reference presents an overview of the state of the art in video coding technology. Specifically, the book introduces the tools of the AVS2 standard, describing how AVS2 can help to achieve a significant improvement in coding efficiency for future video networks and applications by incorporating smarter coding tools such as scene video coding. Topics and features: introduces the basic concepts in video coding, and presents a short history of video coding technology and standards; reviews the coding framework, main coding tools, and syntax structure of AV

  1. Polyphase alternating codes

    M. Markkanen

    2008-08-01

    Full Text Available We present a new class of alternating codes. Instead of the customary binary phase codes, the new codes utilize either p or p–1 phases, where p is a prime number. The first class of codes has code length pm, where m is a positive integer, the second class has code length p–1. We give an actual construction algorithm, and explain the principles behind it. We handle a few specific examples in detail. The new codes offer an enlarged collection of code lengths for radar experiments.

  2. Coding for dummies

    Abraham, Nikhil

    2015-01-01

    Hands-on exercises help you learn to code like a pro No coding experience is required for Coding For Dummies,your one-stop guide to building a foundation of knowledge inwriting computer code for web, application, and softwaredevelopment. It doesn't matter if you've dabbled in coding or neverwritten a line of code, this book guides you through the basics.Using foundational web development languages like HTML, CSS, andJavaScript, it explains in plain English how coding works and whyit's needed. Online exercises developed by Codecademy, a leading online codetraining site, help hone coding skill

  3. Thermo-mechanical behavior of high level horizontal disposal cell during the period of exploitation under the heterogeneous load

    Document available in extended abstract form only. The present work aims to study the evolution of the thermo-mechanical behavior of a horizontal disposal cell under the heterogeneous load during the period of exploitation of 100 years. This heterogeneity of load is due to the generated heat of seven high level waste packages of 1.6 m long which are intercalary disposed in 30 m of the horizontal cell following the concept in 2005 of ANDRA. The analyses have been conducted with different scenarios. The first one consists of modeling the whole length of the disposal cell but the lining is not taken into account for the sake of simplicity. In this case, the generated heat is heterogeneously distributed along the surface of cell. Precisely, at each position of 1.6 m of these seven disposal packages, the uniform heat flux calculated from the thermal power of a high level (HA-C5) waste package is imposed. The model 3D vertically extended from the natural surface to 1000 m of profound allows to account the Callovo-Oxfordian clay as well as its surrounding layers. Moreover, the length of model following the axial direction of the disposal cell is taken equal to 53 m which corresponds to the half distance between axes of the access drift. Following the other horizontal direction which is perpendicular to the axis of cell, a length of 6 m is considered by assuming the symmetrical condition between two disposal cells. This case of study using the coarse mesh is then completed by another model with only 2.35 m of length in the axial direction of disposal cell which allows to increase the precision of the results by using a finer mesh. This length represents a half of a waste package and a half of intercalary distance between two packages. Similarly to the first case, the uniform thermal flux of the half package is imposed on 0.8 m of the wall of the horizontal cell. The thermo-mechanical behavior of materials was used in all simulations by using the Flac3D (ITASCA) code based

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

    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

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

    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 σM. Using classical plasticity theory, Tvergaard elegantly derived an evolution equation for σM. 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 allowed

  6. Modelling of the thermomechanical behaviour of saturated clays: application to the radioactive wastes disposal

    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 fc and the translation of the thermal yield surface fT (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

  7. Thermo-mechanical fatigue behavior of a single crystal nickel-based superalloy

    Highlights: → The thermo-mechanical fatigue life of OP TMF is shorter than that of IP TMF. This is mainly attributed to the maximum tensile stress level at the minimum temperature. → Under out-of-phase condition, damage is controlled by oxidation. While under in-phase condition, damage is controlled by creep. → In terms of the fracture surface and microstructural evolution under different conditions, deformation and damage mechanisms are explained based on the relative contribution of oxidation, creep and fatigue. - Abstract: Thermo-mechanical fatigue (TMF) behavior in a oriented nickel-based single crystal superalloy was investigated under different cycles of strain and temperature. Fracture surface and microstructural evolution were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. It was found that the fatigue lives under in-phase (IP) TMF were longer than those of out-of-phase (OP) TMF, and the maximum tensile stress level was concluded to be the lifetime-limiting factor. Compared to isothermal low-cycle fatigue (LCF) lives obtained under the maximum temperature 900 deg. C, thermo-mechanical fatigue lifetime was much shorter. This result indicates that varying temperature superimposed mechanical strain greatly reduces the fatigue lifetime of superalloys. Based on observation of fracture surface and microstructure evolution, it was concluded that creep is the dominant damage mechanism under IP-TMF condition and oxidation causes shorter lifetime for OP-TMF tests. The similarities and differences in the changes of γ' morphology during in-phase (IP) and out-of-phase (OP) TMF tests were also discussed.

  8. Study of the damaging mechanisms of a carbon - carbon composite bonded to copper under thermomechanical loading; Etude des mecanismes d'endommagement d'un assemblage cuivre / composite carbone - carbone sous chargement thermomecanique

    Moncel, L

    1999-06-15

    The purpose of this work is to understand and to identify the damaging mechanisms of Carbon-Carbon composite bonded to copper under thermomechanical loading. The study of the composite allowed the development of non-linear models. These ones have been introduced in the finite elements analysis code named CASTEM 2000. They have been validated according to a correlation between simulation and mechanical tests on multi-material samples. These tests have also permitted us to better understand the behaviour of the bonding between composite and copper (damaging and fracture modes for different temperatures) under shear and tensile loadings. The damaging mechanisms of the bond under thermomechanical loading have been studied and identified according to microscopic observations on mock-ups which have sustained thermal cycling tests: some cracks appear in the composite, near the bond between the composite and the copper. The correlation between numerical and experimental results have been improved because of the reliability of the composite modelization, the use of residual stresses and the results of the bond mechanical characterisation. (author)

  9. Study of the damaging mechanisms of a copper / carbon - carbon composite under thermomechanical loading; Etude des mecanismes d'endommagement d'un assemblage cuivre / composite carbone - carbone sous chargement thermomecanique

    Moncel, L

    1999-06-18

    The purpose of this work is to understand and to identify the damaging mechanisms of Carbon-Carbon composite bonded to copper under thermomechanical loading. The study of the composite allowed the development of non-linear models. These ones have been introduced in the finite elements analysis code named CASTEM2000. They have been validated according to a correlation between simulation and mechanical tests on multi-material samples. These tests have also permitted us to better understand the behaviour of the bonding between composite and copper (damaging and fracture modes for different temperatures) under shear and tensile loadings. The damaging mechanisms of the bond under thermomechanical loading have been studied and identified according to microscopic observations on mock-ups which have sustained thermal cycling tests: some cracks appear in the composite, near the bond between the composite and the copper. The correlation between numerical and experimental results have been improved because of the reliability of the composite modelization, the use of residual stresses and the results of the bond mechanical characterization. (author)

  10. Calculation of the linear heat generation rates which violate the thermomechanical limit of plastic deformation of the fuel cladding in function of the burn up of a BWR fuel rod type

    The linear heat generation rates (LHGR) for a BWR type generic fuel rod, as function of the burnup that violate the thermomechanical limit of circumferential plastic deformation of the can (canning) in nominal operation in stationary state of the fuel rod are calculated. The evaluation of the LHGR in function of the burnt of the fuel, is carried out under the condition that the deformation values of the circumferential plastic deformation of the can exceeds in 0.1 the thermomechanical value operation limit of 1%. The results of the calculations are compared with the generation rates of linear operation heat in function of the burnt for this fuel rod type. The calculations are carried out with the FEMAXI-V and RODBURN codes. The results show that for exhibitions or burnt between 0 and 16,000 M Wd/tU a minimum margin of 160.8 W/cm exists among LHGR (439.6 W/cm) operation peak for the given fuel and maximum LHGR of the fuel (calculated) to reach 1.1% of circumferential plastic deformation of the can, for the peak factor of power of 1.40. For burnt of 20,000 MWd/tU and 60,000 MWd/tU exist a margin of 150.3 and 298.6 W/cm, respectively. (Author)

  11. Coupling CFD code with system code and neutron kinetic code

    Vyskocil, Ladislav, E-mail: Ladislav.Vyskocil@ujv.cz; Macek, Jiri

    2014-11-15

    Highlights: • Coupling interface between CFD code Fluent and system code Athlet was created. • Athlet code is internally coupled with neutron kinetic code Dyn3D. • Explicit coupling of overlapped computational domains was used. • A coupled system of Athlet/Dyn3D+Fluent codes was successfully tested on a real case. - Abstract: The aim of this work was to develop the coupling interface between CFD code Fluent and system code Athlet internally coupled with neutron kinetic code Dyn3D. The coupling interface is intended for simulation of complex transients such as Main Steam Line Break scenarios, which cannot be modeled separately first by system and neutron kinetic code and then by CFD code, because of the feedback between the codes. In the first part of this article, the coupling method is described. Explicit coupling of overlapped computational domains is used in this work. The second part of the article presents a demonstration simulation performed by the coupled system of Athlet/Dyn3D and Fluent. The “Opening a Steam Dump to the Atmosphere” test carried out at the Temelin NPP (VVER-1000) was simulated by the coupled system. In this simulation, the primary and secondary circuits were modeled by Athlet, mixing in downcomer and lower plenum was simulated by Fluent and heat generation in the core was calculated by Dyn3D. The results of the simulation with Athlet/Dyn3D+Fluent were compared with the experimental data and the results from a calculation performed with Athlet/Dyn3D without Fluent.

  12. Coupling CFD code with system code and neutron kinetic code

    Highlights: • Coupling interface between CFD code Fluent and system code Athlet was created. • Athlet code is internally coupled with neutron kinetic code Dyn3D. • Explicit coupling of overlapped computational domains was used. • A coupled system of Athlet/Dyn3D+Fluent codes was successfully tested on a real case. - Abstract: The aim of this work was to develop the coupling interface between CFD code Fluent and system code Athlet internally coupled with neutron kinetic code Dyn3D. The coupling interface is intended for simulation of complex transients such as Main Steam Line Break scenarios, which cannot be modeled separately first by system and neutron kinetic code and then by CFD code, because of the feedback between the codes. In the first part of this article, the coupling method is described. Explicit coupling of overlapped computational domains is used in this work. The second part of the article presents a demonstration simulation performed by the coupled system of Athlet/Dyn3D and Fluent. The “Opening a Steam Dump to the Atmosphere” test carried out at the Temelin NPP (VVER-1000) was simulated by the coupled system. In this simulation, the primary and secondary circuits were modeled by Athlet, mixing in downcomer and lower plenum was simulated by Fluent and heat generation in the core was calculated by Dyn3D. The results of the simulation with Athlet/Dyn3D+Fluent were compared with the experimental data and the results from a calculation performed with Athlet/Dyn3D without Fluent

  13. Thermo-mechanical and isothermal fatigue behavior of austenitic stainless steel AISI 316L

    Škorík, Viktor; Šulák, Ivo; Obrtlík, Karel; Polák, Jaroslav

    Ostrava: TANGER Ltd, 2015. ISBN 978-80-87294-58-1. [METAL 2015 - International Conference on Metallurgy and Materials /24./. Brno (CZ), 03.06.2015-05.06.2015] R&D Projects: GA MŠk(CZ) EE2.3.30.0063; GA ČR(CZ) GA15-20991S; GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : Thermo-mechanical fatigue (TMF) * In-phase cycling (IP) * Isothermal fatigue (IF) * AISI 316L * Fatigue life Subject RIV: JL - Materials Fatigue, Friction Mechanics

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

    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.

  15. Microstructuring of thermo-mechanically highly stressed surfaces final report of the DFG research group 576

    Rienäcker, Adrian; Knoll, Gunter; Bach, Friedrich-Wilhelm; Maier, Hans; Reithmeier, Eduard; Dinkelacker, Friedrich

    2015-01-01

    This contributed volume presents the final research results of the DFG Research Group 576, which is a joint initiative of five different institutes of the Leibniz Universität Hannover and the Universität Kassel, Germany. The research of the DFG Research Group 576 focuses on improving the tribological behavior of thermomechanically highly stressed surfaces, particularly on cylinder liner for combustion engines. The target audience primarily comprises researchers and experts in the field but the book may also be beneficial for graduate students who want to specialize in the field.

  16. Thermomechanical theory of materials undergoing large elastic and viscoplastic deformation (AWBA development program)

    A thermomechanical theory of large deformation elastic-inelastic material behavior is developed which is based on a multiplicative decomposition of the strain. Very general assumptions are made for the elastic and inelastic constitutive relations and effects such as thermally-activated creep, fast-neutron-flux-induced creep and growth, annealing, and strain recovery are compatible with the theory. Reduced forms of the constitutive equations are derived by use of the second law of thermodynamics in the form of the Clausius-Duhem inequality. Observer invariant equations are derived by use of an invariance principle which is a generalization of the principle of material frame indifference

  17. Influence of cooling in the process of deformation on thermomechanical treatment effect conservation during hot rolling

    Studied is the effect of the metal cooling rate in the deformation process and after it, on the retention of high-temperature thermomechanical treatment effect for low-carbon and low-alloy steels. It is shown that for the steels studied at the similar degree of deformation the maximum HTMT effect is practically uniform, but it's retention is determined by the steel composition. The increase of degree of deformation increases the HTMT effect. The metal cooling rate increase in hot rolling promotes the increase of the complex of mechanical properties at the expense of the more complete use of the HTMT effect

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

    Tutum, Cem Celal

    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 models of the process were developed to simulate temperature and stress evolution during welding and subsequent cooling, i.e. eventually leading to the residual stress state and reduced mechanical properties, as well as to predict the final weld's load carrying capacity. These models were finally...

  19. Fluka and thermo-mechanical studies for the CLIC main dump

    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.

  20. Multiaxial and Thermomechanical Fatigue of Materials: A Historical Perspective and Some Future Challenges

    Kalluri, Sreeramesh

    2013-01-01

    Structural materials used in engineering applications routinely subjected to repetitive mechanical loads in multiple directions under non-isothermal conditions. Over past few decades, several multiaxial fatigue life estimation models (stress- and strain-based) developed for isothermal conditions. Historically, numerous fatigue life prediction models also developed for thermomechanical fatigue (TMF) life prediction, predominantly for uniaxial mechanical loading conditions. Realistic structural components encounter multiaxial loads and non-isothermal loading conditions, which increase potential for interaction of damage modes. A need exists for mechanical testing and development verification of life prediction models under such conditions.

  1. On phase transformation models for thermo-mechanically coupled response of Nitinol

    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.

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

    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/m2 is assumed, which gives larger effects than the case with 6 W/m2. 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-level layouts

  3. DESIGN OPTIMIZATION OF A FUSION REACTOR DIVERTOR COOLING FINGER DESIGN FOR DECREASED THERMO-MECHANICAL STRESSES

    MATTEOLI CAMILLA; Martin, Oliver; SIMONOVSKI IGOR

    2012-01-01

    In this paper a design of a divertor cooling finger for a fusion reactor is looked at with the aim of reducing the thermo-mechanical stresses. The function of a divertor in a fusion reactor is to reduce the dilution of the plasma by removing alpha particles, helium and other impurities. In addition, this component has to remove approximately 15% of the total thermal power. The divertor is therefore exposed to a significant thermal load, and during the operation it has to be actively cooled, w...

  4. Teseo code validation

    In this report some validation tests for the TESEO code are described. The TESEO code was developed at ENEA - Clementel Center in the framework of the C2RV code sequence. This code sequence produces multigroup resonance cross sections for fast reactor analysis. It consists of the codes TESEO, MC2-II, GERES, ANISN, MEDIL. The TESEO code processes basic nuclear data in ENDF-B format and produces an ultrafine group (2082 groups) cross section library for the MC2-II code. To validate the TESEO algorithms, the data produced by TESEO code were compared with the data produced by other well-tested codes which use different algorithms. No substantial differences was found between these data and the data produced by TESEO code. TESEO algorithms showed high reliability. A detailed study of TESEO calculation options was carried out. Their use and functions are shown to inform the user of the code

  5. Experimental study of the stacking sequence effect on polymer/composite multi-layers submitted to thermomechanical cyclic loadings

    Bertin, Maxime; Touchard, Fabienne; Lafarie-Frenot, Marie-Christine [Institut Pprime CNRS - ENSMA - Universite de Poitiers, Departement Physique et Mecanique des Materiaux, ENSMA - Teleport 2, 1, avenue Clement Ader BP 40109 F86961 FUTUROSCOPE CHASSENEUIL Cedex (France)

    2010-10-15

    Fast filling of hydrogen pressure tank leads to thermomechanical stresses in vessel structure. In this paper, the aim is to study the thermomechanical behaviour of the material used in the vessel structure. Flat coupons made of the same constituents as the hydrogen tank materials and with different stacking sequences have been tested under quasi-static tensile tests and fatigue. Three types of fatigue tests have been performed in order to understand damage mechanisms due to interactions between thermal and mechanical stresses: thermomechanical fatigue, 1 Hz mechanical fatigue and mechanical fatigue with a constant stress level stage. Damage development has been followed by acoustic emission and microscopic observations. Results show that, whatever the applied loading, there is a significant influence of the stacking sequence of the composite part. Moreover, the comparison of the material response to the different types of fatigue has revealed the harmful role of coupled temperature/mechanical cyclic stresses. (author)

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

    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)

  7. Optimization of thermomechanical processes in Cu-Cr-Zr lead frame alloy using neural networks and genetic algorithms

    SU; Juanhua; LIU; Ping; DONG; Qiming; LI; Hejun

    2005-01-01

    The thermomechanical treatment process is effective in enhancing the properties of the lead frame copper alloy. In this study, an optimal pattern of the thermomechanical processes for Cu-Cr-Zr was investegated using an intelligent control technique consisting of neural networks and genetic algorithms. The input parameters of the artificial neural network (ANN) are the reduction ratio of cold rolling, aging temperature and aging time. The outputs of the ANN model are the two most important properties of hardness and conductivity. Based on the successfully trained ANN model,genetic algorithms (GA) are used to optimize the input parameters of the model and select perfect combinations of thermomechanical processing parameters and properties.The good generalization performance and optimized results of the integrated model are achieved.

  8. Determination of Constitutive Equation for Thermo-mechanical Processing of INCONEL 718 Through Double Multivariate Nonlinear Regression Analysis

    Hussain, Mirza Zahid; Li, Fuguo; Wang, Jing; Yuan, Zhanwei; Li, Pan; Wu, Tao

    2015-07-01

    The present study comprises the determination of constitutive relationship for thermo-mechanical processing of INCONEL 718 through double multivariate nonlinear regression, a newly developed approach which not only considers the effect of strain, strain rate, and temperature on flow stress but also explains the interaction effect of these thermo-mechanical parameters on flow behavior of the alloy. Hot isothermal compression experiments were performed on Gleeble-3500 thermo-mechanical testing machine in the temperature range of 1153 to 1333 K within the strain rate range of 0.001 to 10 s-1. The deformation behavior of INCONEL 718 is analyzed and summarized by establishing the high temperature deformation constitutive equation. The calculated correlation coefficient ( R) and average absolute relative error ( AARE) underline the precision of proposed constitutive model.

  9. Enhanced thermomechanical functionality of a laser processed hybrid NiTi–NiTiCu shape memory alloy

    The exciting thermomechanical behavior of NiTi shape memory alloys (SMAs) has sparked significant research effort seeking to exploit their exotic properties. The performance capabilities of conventional NiTi offerings are limited, however, by current fabrication technologies. In this study, a high power density laser source was implemented to locally alloy Cu into a conventional NiTi material. The effects of laser processing created a localized NiTiCu ternary material domain which possessed a set of unique thermomechanical properties. The combined active responses of the laser processed hybrid NiTi–NiTiCu SMA represent an enhanced material functionality, which permits a multi-stage thermomechanical recovery and allows for unprecedented novel applications to be realized. (paper)

  10. An application of the LOCA code Cupidon: an assessment of the cladding behaviour in the flash tests

    The Cupidon code has been developed to analyze the thermo-mechanical behaviour of a fuel rod during a Loss Of Coolant Experiment. Models included are drawn from out-of-pile results such Edgar and the first use is to predict and calculate the tests carried out in the Phebus facility. Although the Flash program initiated at Grenoble is devoted to the study of fission product release during a LOCA (Loss Of Coolant Accident), interesting informations have been obtained on in-pile cladding deformation during transients. Analyses of the PIE (Post Irradiated Examination) results in the two first experiments with Cupidon code have shown fairly good agreement regarding diametral strain

  11. State of art in FE-based fuel performance codes

    Finite element (FE) method that is reliable and proven solution in mechanical field has been introduced into fuel performance codes for multidimensional analysis. The present state of the art in numerical simulation of FE-based fuel performance predominantly involves 2-D axisymmetric model and 3-D volumetric model. The FRAPCON and FRAPTRAN own 1.5-D and 2-D FE model to simulate PCMI and cladding ballooning. In 2-D simulation, the FALCON code, developed by EPRI, is a 2-D (R-Z and R-θ) fully thermal-mechanically coupled steady-state and transient FE-based fuel behavior code. The French codes TOUTATIS and ALCYONE which are 3-D, and typically used to investigate localized behavior. In 2008, the Idaho National Laboratory (INL) has been developing multidimensional (2-D and 3-D) nuclear fuel performance code called BISON. In this paper, the current state of FE-based fuel performance code and their models are presented. Based on investigation into the codes, requirements and direction of development for new FE-based fuel performance code can be discussed. Based on comparison of models in FE-based fuel performance code, status of art in the codes can be discussed. A new FE-based fuel performance code should include typical pellet and cladding models which all codes own. In particular, specified pellet and cladding model such as gaseous swelling and high burnup structure (HBS) model should be developed to improve accuracy of code as well as consider AC condition. To reduce computation cost, the approximated gap and the optimized contact model should be also developed. Nuclear fuel operates in an extreme environment that induces complex multiphysics phenomena, occurring over distances ranging from inter-atomic spacing to meters, and times scales ranging from microseconds to years. This multiphysics behavior is often tightly coupled, a well known example being the thermomechanical behavior. Adding to this complexity, important aspects of fuel behavior are inherently

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

    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

  13. FAVOR: A new fracture mechanics code for reactor pressure vessels subjected to pressurized thermal shock

    This report discusses probabilistic fracture mechanics (PFM) analysis which is a major element of the comprehensive probabilistic methodology endorsed by the NRC for evaluation of the integrity of Pressurized Water Reactor (PWR) pressure vessels subjected to pressurized-thermal-shock (PTS) transients. It is anticipated that there will be an increasing need for an improved and validated PTS PFM code which is accepted by the NRC and utilities, as more plants approach the PTS screening criteria and are required to perform plant-specific analyses. The NRC funded Heavy Section Steel Technology (HSST) Program at Oak Ridge National Laboratories is currently developing the FAVOR (Fracture Analysis of Vessels: Oak Ridge) PTS PFM code, which is intended to meet this need. The FAVOR code incorporates the most important features of both OCA-P and VISA-II and contains some new capabilities such as PFM global modeling methodology, the capability to approximate the effects of thermal streaming on circumferential flaws located inside a plume region created by fluid and thermal stratification, a library of stress intensity factor influence coefficients, generated by the NQA-1 certified ABAQUS computer code, for an adequate range of two and three dimensional inside surface flaws, the flexibility to generate a variety of output reports, and user friendliness

  14. A study on the free drop impact of a cask using commercial FEA codes

    The package used to transport radioactive materials, which is called a cask, must be designed to keep its contents safe under normal and hypothetical accident conditions. The design requirements of the cask are verified by test or finite element analysis (FEA). Comparing evaluation procedures for the safety of a new cask, the cost of FEA is generally much less than that test. Therefore, FEA is mainly used to verify safety of a cask under the considered conditions. However, one commercial FEA code may show different results from another FEA code for the same problem due to the modeler's several assumptions for simplifying actual states into the FE model and due to modeling technique. Materials of the components of a cask display elastic-plastic or elastic-perfectly plastic behavior under the considered conditions in which large deformation, impact and contact mechanism are included. The behavior is simulated with difficulty and may have different results depending on FEA codes. In this paper, finite element analysis is carried out for the 9-m free drop and the puncture condition under the hypothetical accident condition by using LS-DYNA3D and ABAQUS/Explicit. Energy and effective stress on each component are presented and compared between the two FEA codes, where the effective stress designates the maximum von Mises stress on inner and outer shells

  15. Effect of thermomechanical treatment on mechanical properties and electrical conductivity of a CuCrZr alloy

    G Durashevich; V Cvetkovski; V Jovanovich

    2002-02-01

    The CuCrZr alloy undergoes processes of precipitation during ageing. Besides precipitation hardening the strength is affected by cold deformation which is performed before and after ageing. The cold deformation (1) before ageing accelerates the process of strength hardening, since it induces higher rate of precipitation from the saturated -solid solution. Cold deformation (2) after ageing primarily affects the alloy strength. In this paper the results of the effect of thermomechanical treatment on mechanical properties and electrical conductivity of a CuCrZr alloy are presented. The aim of the paper was to evaluate the most suitable combination of thermomechanical treatment and alloy properties.

  16. Local experimental investigations of the thermomechanical behavior of a coarse-grained aluminum multicrystal using combined DIC and IRT methods

    Li, L.; Muracciole, J.-M.; Waltz, L.; Sabatier, L.; Barou, F.; Wattrisse, B.

    2016-06-01

    This paper presents Digital Image Correlation (DIC) and Infrared Thermography (IRT) methods to investigate the thermomechanical behavior of an aluminum at the microstructural scale. Electron BackScattered Diffraction (EBSD) is used to characterize the microstructure of a 3 mm thick specimen with centimetric grain size. This study combines the following imaging techniques: DIC to obtain displacement and strain fields during the test, and IRT to estimate temperature and heat source fields induced by the mechanical loading. Ultimately, the aim of this methodology is to provide energy balance during mechanical test at the scale of the microstructure, in order to propose thermomechanical constitutive modelling of crystalline plasticity.

  17. Locally Orderless Registration Code

    2012-01-01

    This is code for the TPAMI paper "Locally Orderless Registration". The code requires intel threadding building blocks installed and is provided for 64 bit on mac, linux and windows.......This is code for the TPAMI paper "Locally Orderless Registration". The code requires intel threadding building blocks installed and is provided for 64 bit on mac, linux and windows....

  18. Decentralized Network Coding

    Fragouli, C.; Soljanin, E.

    2004-01-01

    This paper proposes deterministic algorithms for decentralized network coding. Decentralized coding allows to locally specify the coding operations at network nodes without knowledge of the overall network topology, and to accommodate future changes in the network such as addition of receivers. To the best of our knowledge, these are the first deterministic decentralized algorithms proposed for network coding.

  19. FAVOR: A new fracture mechanics code for reactor pressure vessels subjected to pressurized thermal shock

    Probabilistic fracture mechanics (PFM) analysis is a major element of the comprehensive probabilistic methodology endorsed by the Nuclear Regulatory Commission (NRC) for evaluation of the integrity of pressurized water reactor pressure vessels subjected to pressurized-thermal-shock (PTS) transients. OCA-P and VISA-II are PTS PFM computer codes that are currently referenced in Regulatory Guide 1.154 as acceptable codes for performing plant-specific analyses. These codes perform PFM analyses to estimate the increase in vessel failure probability as the vessel accumulates radiation damage over the operating life of the vessel. Experience with the application of these codes in the last few years has provided insights into areas where they could be improved. As more plants approach the PTS screening criteria and are required to perform plant-specific analyses, there will be an increasing need for an improved and validated PTS PFM code that is accepted by the NRC and utilities. The NRC funded Heavy Section Steel Technology Program (HSST) at the Oak Ridge National Laboratory is currently developing the FAVOR (Fracture Analysis of Vessels: Oak Ridge) code, which is expected to meet this need. The FAVOR code incorporates the most important features of both OCA-P and VISA-II and contains some new capabilities such as (1) a PFM global modeling methodology; (2) the calculation of the axial stress component associated with coolant streaming beneath an inlet nozzle; (3) a library of stress intensity factor influence coefficients, generated by the NQA-1 certified ABAQUS computer code, for an appropriate range of two and three dimensional inner-surface flaws; (4) the flexibility to generate a variety of output reports; and (5) enhanced user friendliness

  20. The Aesthetics of Coding

    Andersen, Christian Ulrik

    2007-01-01

    code, etc.). The presentation relates this artistic fascination of code to a media critique expressed by Florian Cramer, claiming that the graphical interface represents a media separation (of text/code and image) causing alienation to the computer’s materiality. Cramer is thus the voice of a new ‘code...... discusses code as the artist’s material and, further, formulates a critique of Cramer. The seductive magic in computer-generated art does not lie in the magical expression, but nor does it lie in the code/material/text itself. It lies in the nature of code to do something – as if it was magic: in the...

  1. QR Codes 101

    Crompton, Helen; LaFrance, Jason; van 't Hooft, Mark

    2012-01-01

    A QR (quick-response) code is a two-dimensional scannable code, similar in function to a traditional bar code that one might find on a product at the supermarket. The main difference between the two is that, while a traditional bar code can hold a maximum of only 20 digits, a QR code can hold up to 7,089 characters, so it can contain much more…

  2. Polyphase alternating codes

    Markkanen, Markku

    2007-01-01

    This work introduces a method for constructing polyphase alternating codes in which the length of a code transmission cycle can be $p^m$ or $p-1$, where $p$ is a prime number and $m$ is a positive integer. The relevant properties leading to the construction alternating codes and the algorithm for generating alternating codes is described. Examples of all practical and some not that practical polyphase code lengths are given.

  3. Constructing quantum codes

    2008-01-01

    Quantum error correcting codes are indispensable for quantum information processing and quantum computation.In 1995 and 1996,Shor and Steane gave first several examples of quantum codes from classical error correcting codes.The construction of efficient quantum codes is now an active multi-discipline research field.In this paper we review the known several constructions of quantum codes and present some examples.

  4. Thermo-mechanical Analysis for the Conceptual Design of Korean HCCR TBM-set

    The HCCR TBM shall be installed in the equatorial port No.18 of ITER inside the vacuum vessel, which is directly faced the plasma, and shall be cooled by a high-temperature He coolant of 300 .deg. C. And the 'shield', which is a water-cooled low-temperature (70 .deg. C), shall be placed behind the TBM and it shall be connected with the water-coolant system of the frame. But the detailed design of key is in progress, and evaluated to satisfy the design criteria. In this study the thermo-mechanical (TM) analysis was carried out to satisfy the design requirement using ANSYS. The material of TBM-set is obtained from the reference, and RCC-MRx for the stress analysis. The HCCR TBM uses the RAFM steel, called Advanced Reduced Activation Alloy (ARAA) developed by Korea recently, as a structural material, but Eurofer was used for the thermo-mechanical analysis because of insufficient data of ARAA material as a Korea strategy. And other structure material such a s the shield, back manifold (BM), etc. in the TBM set has considered to be made by 316L(N)-IG. It was concluded that the current design of HCCR TBM-set meet the design criteria according to RCC-MRx from the investigation of stress distribution from each component in TBM-set, and stress breakdown analysis

  5. Modeling of thermo-mechanical fatigue and damage in shape memory alloy axial actuators

    Wheeler, Robert W.; Hartl, Darren J.; Chemisky, Yves; Lagoudas, Dimitris C.

    2015-04-01

    The aerospace, automotive, and energy industries have seen the potential benefits of using shape memory alloys (SMAs) as solid state actuators. Thus far, however, these actuators are generally limited to non-critical components or over-designed due to a lack of understanding regarding how SMAs undergo thermomechanical or actuation fatigue and the inability to accurately predict failure in an actuator during use. The purpose of this study was to characterize the actuation fatigue response of Nickel-Titanium-Hafnium (NiTiHf) axial actuators and, in turn, use this characterization to predict failure and monitor damage in dogbone actuators undergoing various thermomechanical loading paths. Calibration data was collected from constant load, full cycle tests ranging from 200-600MPa. Subsequently, actuator lifetimes were predicted for four additional loading paths. These loading paths consisted of linearly varying load with full transformation (300-500MPa) and step loads which transition from zero stress to 300-400MPa at various martensitic volume fractions. Thermal cycling was achieved via resistive heating and convective cooling and was controlled via a state machine developed in LabVIEW. A previously developed fatigue damage model, which is formulated such that the damage accumulation rate is general in terms of its dependence on current and local stress and actuation strain states, was utilized. This form allows the model to be utilized for specimens undergoing complex loading paths. Agreement between experiments and simulations is discussed.

  6. Development of Be/DSCu HIP bonding and thermo-mechanical evaluation

    The hot isostatic pressing (HIP) joining condition and interlayer materials for Be and DSCu joining have been examined. Based on the screening test results, two HIP conditions and interlayer materials were selected for mock-up fabrication. The first technology uses an Al-Si-Mg foil inserted between the beryllium tile coated by an Al layer and the DSCu heat sink coated by an Al/Ti/Cu layer at the HIP temperature of 555 deg. C. Another technology uses a DSCu heat sink coated by a pure Cu layer at the HIP temperature of 620 deg. C. The latter technology provided the highest strength of the Be/DSCu joints. Heating tests at heat flux of 5 MW/m2 up to 1000 were performed to compare with thermo-mechanical performance. Though the HIP technology with the Al-Si-Mg foil had lower strength, the thermo-mechanical performance of the mock-up was better, than the performance of the mock-up with the pure Cu interlayer. The presence of the Al and Al-Si-Mg interlayers act as effective compliant layers between beryllium and DSCu

  7. Mechanical and thermomechanical properties of radiation modified poly(ethylene-octene)/Ni-Zn ferrite nanocomposites

    Poly(ethylene-1-octene) copolymer (POE) composites filled with nickel-zinc ferrite nanoparticles have been modified by exposure to an electron beam at doses up to 500 kGy. The influence of radiation dose and ferrite content on mechanical properties has been investigated. Thermomechanical properties – thermorelaxation stresses formed in thermal heating and thermo residual stresses resulting in the process of full setting and cooling of materials have been investigated for radiation cross-linked oriented (extended up to 100%) composite samples. Increase of concentration of ferrite particles and increase of radiation dose affects a notable increase of elastic modulus and reduces the deformability in comparison to entire elastomer. Improvement of thermomechanical properties especially at low irradiation doses (100–150 kGy) have been detected for composites with increase of ferrite filler content up to 5 wt. %. It was found that gel content of POE increased up to 85% for pristine POE material with increase of irradiation dose up to 500 kGy due to the formation of cross-linked structure, increase of filler concentration up to 5 wt. % affect reduction in gel fraction due to uniform dispersion in amorphous (ethylene and substituted with hexyl branches) POE phases

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

    Saeed Tourchi; Amir Hamidi

    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 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 cali-bration is also described. The model is finally evaluated using a comprehensive set of experimental data for the thermo-mechanical behavior of unsaturated soils.

  9. Repetitive Thermomechanical Processing towards Ultra Fine Grain Structure in 301, 304 and 304L Stainless Steels

    A. Momeni; S.M. Abbasi

    2011-01-01

    Thermomechanical processing as a combination of cold rolling and annealing was performed on austenitic stainless steels 301,304 and 304L. Two cold rolling steps each one up to a reduction of 75% were combined with an intermediate annealing at 800℃ for 20 min. The final annealing was performed at.the same temperature and time. Cold rolling contributed to martensite formation at the expense of metastable austenite in the studied materials. Austenite in 301 was found to be less stable than that in 304 and 304L. Hence, higher strength characteristics in the as-quenched 301 stainless steels were attributed to the higher volume fraction of martensite. Both α'-martensite and ε-martensite were found to form as induced by deformation. However, the intensity of ε-martensite increased as the stability of austenite decreased. Annealing after cold rolling led to the reversion of austenite with an ultra fine grained structure in the order of 0.5-1 μm from the strain induced martensite. The final grain size was found to be an inverse function of the amount of strain induced martensite. The thermomechanical processing considerably improved the strength characteristics while the simultaneous decrease of elongation was rather low.

  10. Thermo-mechanical Analysis for the Conceptual Design of Korean HCCR TBM-set

    Lee, Dong Won; Jin, Hyung Gon; Lee, Eo Hwak; Yoon, Jae Sung; Kim, Suk Kwon [KAERI, Daejeon (Korea, Republic of); Shin, Kyu In [Gentec Tech, Daejeon (Korea, Republic of); Cho, Seungyon [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The HCCR TBM shall be installed in the equatorial port No.18 of ITER inside the vacuum vessel, which is directly faced the plasma, and shall be cooled by a high-temperature He coolant of 300 .deg. C. And the 'shield', which is a water-cooled low-temperature (70 .deg. C), shall be placed behind the TBM and it shall be connected with the water-coolant system of the frame. But the detailed design of key is in progress, and evaluated to satisfy the design criteria. In this study the thermo-mechanical (TM) analysis was carried out to satisfy the design requirement using ANSYS. The material of TBM-set is obtained from the reference, and RCC-MRx for the stress analysis. The HCCR TBM uses the RAFM steel, called Advanced Reduced Activation Alloy (ARAA) developed by Korea recently, as a structural material, but Eurofer was used for the thermo-mechanical analysis because of insufficient data of ARAA material as a Korea strategy. And other structure material such a s the shield, back manifold (BM), etc. in the TBM set has considered to be made by 316L(N)-IG. It was concluded that the current design of HCCR TBM-set meet the design criteria according to RCC-MRx from the investigation of stress distribution from each component in TBM-set, and stress breakdown analysis.

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

    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

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

    Wang, Songke, E-mail: wsongk@ipp.ac.cn; Ji, Xiang; Song, Yuntao; Zhang, Shanwen; Wang, Zhongwei; Sun, Youwen; Qi, Minzhong; Liu, Xufeng; Wang, Shengming; Yao, Damao

    2014-10-15

    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.

  13. Nanomechanical characterization of thermo-mechanical properties of irradiated zirconium with consideration of temperature and microstructure

    Marsh, Jonathan T.

    Zirconium (Zr) and zirconium-alloys have been utilized in the nuclear industry for decades, most commonly in nuclear fuel cladding. The characteristics which make Zr ideal for these applications include: low density, high hardness, high ductility, and high corrosion resistance. Efforts have been made to further enhance these properties through the use of Zr-alloys, such as Zircaloy-2 and Zircaloy-4, which are made up 95-99% Zr by weight, with the remaining weight percentage being made of other metals (tin, niobium, nickel, iron, chromium). The performance of these materials directly influences the efficiency of the nuclear reactor and are thus of primary concern. While the properties of these materials alone have been studied extensively, the nuclear reactor environment itself serves to degrade or enhance these properties, depending on the situation. The coupled effect of irradiation, high temperature, and microstructure is not understood. Each of these aspects uniquely influence the thermo-mechanical properties of these Zr-based materials and a better understanding of these coupled phenomena is necessary to effectively and efficiently design these nuclear reactor components. The aim of the following work is to experimentally investigate the effect of these coupled phenomena on the thermo-mechanical properties and viscoplastic response of Zr.

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

    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.

  15. Fatigue crack growth behavior of a titanium matrix composite under thermomechanical loading. Doctoral thesis

    Blatt, P.A.

    1993-12-01

    The crack growth characteristics of a 4-ply, unidirectional, titanium matrix composite, SCS-6/ti-6Al-2Sn4Zr-2Mo, subjected to thermomechanical fatigue were investigated. A linear summation model was developed to predict the isothermal and thermomechanical fatigue (TMF) crack growth rates of the composite. The linear summation approach assumes the total fatigue crack growth rate is a combination of a cycle-dependent and a time-dependent component. To assist the modeling effort, a series of isothermal, in-phase, and out-of-phase crack growth test were conducted. The test temperatures ranged from 15000 to 53800 and the fastest thermal frequency was 0.0083 Hz. With the excepton of the 15000 isothermal test, the model was able to correlate all the baseline fangue crack growth test data between oK of 50 to 9OMPa. In additon, the model was able to predict the fatigue crack growth rate of a proof test which involved a continual change in temperature range and load range to produce a constant crack growth rate. The proof test began under isothermal conditions at the maximum temperature and ended under in-phase TMF conditions.

  16. A novel approach to computational homogenization and its application to fully coupled two-scale thermomechanics

    Fleischhauer, Robert; Božić, Marko; Kaliske, Michael

    2016-07-01

    The paper introduces a novel approach to computational homogenization by bridging the scales from microscale to macroscale. Whenever the microstructure is in an equilibrium state, the macrostructure needs to be in equilibrium, too. The novel approach is based on the concept of representative volume elements, stating that an assemblage of representative elements should be able to resemble the macrostructure. The resulting key assumption is the continuity of the appropriate kinematic fields across both scales. This assumption motivates the following idea. In contrast to existing approaches, where mostly constitutive quantities are homogenized, the balance equations, that drive the considered field quantities, are homogenized. The approach is applied to the fully coupled partial differential equations of thermomechanics solved by the finite element (FE) method. A novel consistent finite homogenization element is given with respect to discretized residual formulations and linearization terms. The presented FE has no restrictions regarding the thermomechanical constitutive laws that are characterizing the microstructure. A first verification of the presented approach is carried out against semi-analytical and reference solutions within the range of one-dimensional small strain thermoelasticity. Further verification is obtained by a comparison to the classical FE^2 method and its different types of boundary conditions within a finite deformation setting of purely mechanical problems. Furthermore, the efficiency of the novel approach is investigated and compared. Finally, structural examples are shown in order to demonstrate the applicability of the presented homogenization framework in case of finite thermo-inelasticity at different length scales.

  17. Three-dimensional EBSD characterization of thermo-mechanical fatigue crack morphology in compacted graphite iron

    In cylinder heads made of compacted graphitic iron (CGI), heating and cooling cycles can lead to localized cracking due to thermo-mechanical fatigue (TMF). To meticulously characterize the complex crack path morphology of CGI under TMF condition, in relation to microstructural features and to find out how and by which mechanisms the cracks predominantly develop, three-dimensional electron back scattering diffraction (EBSD) was employed. Based on the precise quantitative microstructural analysis, it is found that graphite particles not only play a crucial role in the crack initiation, but also are of primary significance for crack propagation, i.e. crack growth is enhanced by the presence of graphite particles. Furthermore, the density of graphite particles on the fracture plane is more than double as high as in any other arbitrary plane of the structure. The obtained results did not indicate a particular crystallographic preference of fracture plane, i.e. the crystal plane parallel to the fracture plane was nearly of random orientation. - Highlights: • Crystallographic features of a thermo-mechanical fatigue (TMF) crack were studied. • Wide-field 3D EBSD is used to characterize the TMF crack morphology. • Data processing was applied on a large length scale of the order of millimeters. • Graphite density in the fracture plane is much higher than any other random plane. • It is revealed that crack growth is enhanced by the presence of graphite particles

  18. Spectroscopic and thermomechanical properties of new neodymium-doped laser materials

    New solid-state laser media will improve the efficiency, average power, and beam quality of laser systems. Recently gadolinium scandium gallium garnet (GSGG) crystals have produced the highest efficiency laser operation reported for a rod laser. For high-average-power systems enploying the zigzag configuration or the gas-cooled disk configuration, GSGG will be useful for small-aperture systems. In large-aperture systems, new silico-phosphate glasses developed by Hoya Optics and by Schott Glass Technologies have advantages over the presently used LHG-5 phosphate glass. Future lasers for fusion research, which will have megajoule pulse energies, will require an inexpensive phosphate glass with improved thermomechanical characteristics. In the long run laser drivers for inertial confinement fusion reactors will need an efficient low-nonlinear-index crystalline laser medium; fluoride crystals are prime candidates. To evaluate the suitability of materials for these laser applications, the authors are measuring the spectroscopic properties of many new laser glasses and the thermomechanical characteristics of glasses and crystals. They have compiled the property values from the published literature, measurements done by Schott and Hoya, plus their own measurements

  19. Thermomechanical analysis of diffusion-bonded tungsten/EUROFER97 with a vanadium interlayer

    Basuki, Widodo Widjaja; Dahm, Ralf; Aktaa, Jarir

    2014-12-15

    Earlier basic investigations revealed that diffusion bonding between tungsten and RAFM-steel at a relatively low temperature using a thin low-activation vanadium interlayer having a CTE between that of the parent materials can significantly reduce the residual stresses and produce defect-free bond interfaces. The joint has a high strength as well as sufficient ductility and toughness especially at the test temperature of about 550 °C. To apply this knowledge in fusion power plants, particularly in divertors, an acceptable lifetime of such structural joints is required, since they are exposed to high thermomechanical cyclic loading. To simulate the possible operational conditions of a He-cooled divertor, diffusion-bonded specimens are loaded by thermal cycling in a temperature range between 350 °C and 500 °C and a constant tensile stress based on the calculation of the internal pressure of the divertor thimble. The aim of this experimental work is to check the resistance of the diffusion-bonded W/EUROFER97 against ratcheting during thermomechanical loading and analyze the evolution of microstructures of the joint especially along the bond interfaces.

  20. Design of high-strength steels by microalloying and thermomechanical treatment

    Steels with higher strength, ductility and improved fatigue behavior are required for light-weight structures in the transportation industry. It is shown that for martensitic steels the combination of microalloying and an optimized thermomechanical treatment (TMT) results in increased strength and improved ductility. Proper conditioning of the austenite by deformation either refines the austenitic grains or generates a dislocation substructure that is inherited to the martensite structure. In contrast to simply quenched and tempered martensite with no prior deformation, the thermomechanically processed martensite exhibits a more refined structure with refined blocks and is free of grain boundary carbides. Addition of vanadium is beneficial in controlling the austenite grain size during austenitization and for the stabilization of the austenite defect structures that are produced by deformation. It enables to use higher deformation temperatures for TMT, i.e. lower rolling forces can be applied in an industrial process. It is possible to increase the strength and ductility of conventionally heat treated Si-Cr steel by addition of vanadium or by TMT, but the highest improvement is achieved through the combination of both. In this study, an increase of more than 600 MPa in the ultimate tensile strength and an improvement of 40% in the reduction area are reported

  1. IMPROVING THE MECHANICAL PROPERTIES OF COPPER ALLOYS BY THERMO-MECHANICAL PROCESSING

    M.C.Somani; L.P.Karjalainen

    2004-01-01

    Systematic physical simulation of thermo-mechanical processing routes has been applied on a Gleeble 1500 simulator to four copper alloys(mass %)Cu-0.57Co-0.32Si,Cu-0.55Cr-0.065P,Cu-0.22Zr-0.035Si and Cu-1.01Ni-0.43Si aimed at clarifying the influences of processing conditions on their final properties,strength and electrical conductivity.Flow curves were determined over wide temperature and strain rate ranges.Hardness was used as a measure of the strength level achieved.High hardness was obtained as using equal amounts(strains 0.5)of cold deformation before and after the precipitation annealing stage.The maximum values achieved for the Cu-Co-Si,Cu-Cr-P,Cu-Zr-Si and Cu-Ni-Si alloys were 190,165,178 and 193 HV5,respectively.A thermo-mechanical schedule involving the hot deformation-ageing-cold deformation stages showed even better results for the Cu-Zr-Si alloy.Consequently,the processing routes were designed based on simulation test results and wires of 5 and 2mm in diameters have been successfully processed in the industrial scale.

  2. Constitutive Modelling in Thermomechanical Processes, Using The Control Volume Method on Staggered Grid

    Thorborg, Jesper

    The objective of this thesis has been to improve and further develop the existing staggered grid control volume formulation of the thermomechanical equations. During the last ten years the method has proven to be efficient and accurate even for calculation on large structures. The application of ...... to analyse the thermal and mechanical conditions in various components and structures. This will hopefully lead to a useful tool during the process optimization phase.......The objective of this thesis has been to improve and further develop the existing staggered grid control volume formulation of the thermomechanical equations. During the last ten years the method has proven to be efficient and accurate even for calculation on large structures. The application...... of the method has been focused on high temperature processes such as casting and welding and the interest of using nonlinear constitutive stress-strain relations has grown to extend the applicability of the method. The work of implementing classical plasticity into the control volume formulation has been based...

  3. Preliminary thermal and thermomechanical modeling for the Near Surface Test Facility heater experiments at Hanford

    Preliminary thermal and thermomechanical analyses have been carried out for the heater experiments in the Near Surface Test Facility at Gable Mountain on the Hanford Reservation, Richland, Washington. Temperatures were calculated by Green's function method for the full-scale and time-scaled experiments. Six different heater power schedules were considered for the full-scale experiments to bracket all possible values of initial spent fuel power from canisters buried after different periods of cooling. Linear elastic finite-element models were used to calculate the thermally induced displacements and stresses for two of the power schedules. Due to the poor thermal conductivity and rather high Young's modulus of Pomona basalt (the rock type in which the heater experiments are to be conducted), very high temperatures, displacements and stresses were predicted in spite of the relatively low thermal expansion coefficient. These predicted values have been used for the design of the experiments. Recommendations are made in this report regarding the conduct of the experiments and the interpretation of the field data, as well as further thermomechanical modeling and input data required for more meaningful modeling of a fractured rock mass. Equations are given in Appendices A and B for temperatures caused by an arbitrary time-dependent cylindrical heater of finite length and radius, a finite-radius disc heater, as well as the generalization to the situation of an anisotropic medium

  4. Preliminary thermal and thermomechanical modeling for the Near Surface Test Facility heater experiments at Hanford

    Chan, T.; Remer, J.S.

    1978-12-01

    Preliminary thermal and thermomechanical analyses have been carried out for the heater experiments in the Near Surface Test Facility at Gable Mountain on the Hanford Reservation, Richland, Washington. Temperatures were calculated by Green's function method for the full-scale and time-scaled experiments. Six different heater power schedules were considered for the full-scale experiments to bracket all possible values of initial spent fuel power from canisters buried after different periods of cooling. Linear elastic finite-element models were used to calculate the thermally induced displacements and stresses for two of the power schedules. Due to the poor thermal conductivity and rather high Young's modulus of Pomona basalt (the rock type in which the heater experiments are to be conducted), very high temperatures, displacements and stresses were predicted in spite of the relatively low thermal expansion coefficient. These predicted values have been used for the design of the experiments. Recommendations are made in this report regarding the conduct of the experiments and the interpretation of the field data, as well as further thermomechanical modeling and input data required for more meaningful modeling of a fractured rock mass. Equations are given in Appendices A and B for temperatures caused by an arbitrary time-dependent cylindrical heater of finite length and radius, a finite-radius disc heater, as well as the generalization to the situation of an anisotropic medium.

  5. Effect of quinoa and potato flours on the thermomechanical and breadmaking properties ofwheat flour

    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.

  6. Thermo-mechanical simulations of CO2 laser-fused silica interactions

    Doualle, T.; Gallais, L.; Cormont, P.; Hébert, D.; Combis, P.; Rullier, J.-L.

    2016-03-01

    CO2 laser heating of silica glass is used in many scientific and industrial applications. Particularly, localized CO2 laser heating of silica glass has demonstrated its ability to mitigate surface damage on optics used for high power laser applications. To develop such applications, the control of temperature, heat affected area, and resulting mechanical stresses are critical. Therefore, it is necessary to understand the silica transformation, the material ejection, and the thermo-mechanical stresses induced by the laser heating and subsequent cooling. In this paper, we detail the development of comprehensive thermo-mechanical numerical simulations of these physical processes, based on finite-element method. The approach is developed for 2D or 3D cases to tackle the case of a moving beam at the surface of the sample, and we particularly discuss the choice of the different parameters based on bibliographic inputs. The thermal and mechanical numerical results have been compared to different dedicated experimental studies: infrared thermography measurements at the surface of the irradiated area, optical profilometry measurements of the laser-processed sites, and photo-elastic measurements. Very consistent results are obtained between numerical and experimental results for the description of the temperature gradients, the material ejection, and the residual stresses.

  7. Thermomechanical properties and performance of ceramic resonators for wireless pressure reading at high temperatures

    This paper reports on the design, fabrication, and thermomechanical study of ceramic LC resonators for wireless pressure reading, verified at room temperature, at 500 °C and at 1000 °C for pressures up to 2.5 bar. Five different devices were fabricated from high-temperature co-fired ceramics (HTCC) and characterized. Alumina green tape sheets were screen printed with platinum paste, micromachined, laminated, and fired. The resulting samples were 21 mm  ×  19 mm with different thicknesses. An embedded communicator part was integrated with either a passive backing part or with a pressure-sensing element, including an 80 µm thick and 6 mm diameter diaphragm. The study includes measuring thermally and mechanically induced resonance frequency shifts, and thermally induced deformations. For the pressure sensor device, contributions from changes in the relative permittivity and from expanding air trapped in the cavity were extracted. The devices exhibited thermomechanical robustness during heating, regardless of the thickness of the backing. The pressure sensitivity decreased with increasing temperature from 15050 ppm bar−1 at room temperature to 2400 ppm bar−1 at 1000 °C, due to the decreasing pressure difference between the external pressure and the air pressure inside the cavity. (paper)

  8. Development of the enigma fuel performance code for whole core analysis and dry storage assessments

    Rositer, Glyn [Fuel Cycle Solutions, UK National Nuclear Laboratory, Lancashire (United Kingdom)

    2011-11-15

    UK National Nuclear Laboratory's (NNL's) version of the ENIGMA fuel performance code is described, including details of the development history, the system modelled, the key assumptions, the thermo-mechanical solution scheme, and the various incorporated models. The recent development of ENIGMA in the areas of whole core analysis and dry storage applications is then discussed. With respect to the former, the NEXUS code has been developed by NNL to automate whole core fuel performance modelling for an LWR core, using ENIGMA as the underlying fuel performance engine. NEXUS runs on NNL's GEMSTONE high performance computing cluster and utilises 3-D core power distribution data obtained from the output of Studsvik Scandpower's SIMULATE code. With respect to the latter, ENIGMA has been developed such that it can model the thermo-mechanical behaviour of a given LWR fuel rod during irradiation, pond cooling, drying, and dry storage-this involved: (a) incorporating an out-of-pile clad creep model for irradiated Zircaloy-4; (b) including the ability to simulate annealing out of the clad irradiation damage; (c) writing of additional post-irradiation output; (d) several other minor modifications to allow modelling of post-irradiation conditions.

  9. Analysis of the Behavior of CAREM-25 Fuel Rods Using Computer Code BACO

    The thermo-mechanical behavior of a fuel rod subjected to irradiation is a complex process, on which a great quantity of interrelated physical-chemical phenomena are coupled.The code BACO simulates the thermo-mechanical behavior and the evolution of fission gases of a cylindrical rod in operation.The power history of fuel rods, arising from neutronic calculations, is the program input.The code calculates, among others, the temperature distribution and the principal stresses in the pellet and cladding, changes in the porosity and restructuring of pellet, the fission gases release, evolution of the internal gas pressure.In this work some of design limits of CAREM-25's fuel rods are analyzed by means of the computer code BACO.The main variables directly related with the integrity of the fuel rod are: Maximum temperature of pellet; Cladding hoop stresses; Gases pressure in the fuel rod; Cladding axial and radial strains, etc.The analysis of results indicates that, under normal operation conditions, the maximum fuel pellet temperature, cladding stresses, pressure of gases at end of life, etc, are below the design limits considered for the fuel rod of CAREM-25 reactor

  10. Development of the enigma fuel performance code for whole core analysis and dry storage assessments

    UK National Nuclear Laboratory's (NNL's) version of the ENIGMA fuel performance code is described, including details of the development history, the system modelled, the key assumptions, the thermo-mechanical solution scheme, and the various incorporated models. The recent development of ENIGMA in the areas of whole core analysis and dry storage applications is then discussed. With respect to the former, the NEXUS code has been developed by NNL to automate whole core fuel performance modelling for an LWR core, using ENIGMA as the underlying fuel performance engine. NEXUS runs on NNL's GEMSTONE high performance computing cluster and utilises 3-D core power distribution data obtained from the output of Studsvik Scandpower's SIMULATE code. With respect to the latter, ENIGMA has been developed such that it can model the thermo-mechanical behaviour of a given LWR fuel rod during irradiation, pond cooling, drying, and dry storage-this involved: (a) incorporating an out-of-pile clad creep model for irradiated Zircaloy-4; (b) including the ability to simulate annealing out of the clad irradiation damage; (c) writing of additional post-irradiation output; (d) several other minor modifications to allow modelling of post-irradiation conditions.

  11. Objective thermomechanics

    Fülöp, Tamás

    2015-01-01

    An irreversible thermodynamical theory of solids is presented where the kinematic quantities are defined in an automatically objective way. Namely, auxiliary elements like reference frame, reference time and reference configuration are avoided by formulating the motion of the continuum on spacetime directly. Solids are distinguished from fluids by possessing not only an instantaneous metric tensor but also a relaxed metric. The elastic state variable is defined through comparing these two met...

  12. Objective thermomechanics

    Fülöp, Tamás

    2015-01-01

    An irreversible thermodynamical theory of solids is presented where the kinematic quantities are defined in an automatically objective way. Namely, auxiliary elements like reference frame, reference time and reference configuration are avoided by formulating the motion of the continuum on spacetime directly, utilizing the Weyl-Matolcsi description of spacetime. This restricts the range of definable kinematic quantities heavily. Solids are distinguished from fluids by possessing not only an instantaneous metric tensor but a relaxed metric, too, that represents the natural geometric structure of the solid. The comparison of the instantaneous metric to the relaxed one is the basis of the definition of the elastic state variable, the elastic deformedness tensor. Thermal expansion is conceived as the temperature dependence of the relaxed metric. As opposed to this reversible type of change, plasticity means an irreversible change in the relaxed metric, and is describable via a plastic change rate tensor. The relat...

  13. Polyphase alternating codes

    M. Markkanen; Vierinen, J.; Markkanen, J.

    2007-01-01

    We present a new class of alternating codes. Instead of the customary binary phase codes, the new codes utilize either p or p–1 phases, where p is a prime number. The first class of codes has code length pm, where m is a positive integer, the second class has code length p–1. We give an actual construction algorithm, and explain the principles behind it. We ...

  14. Material flow and thermo-mechanical conditions during Friction Stir Welding of polymers: Literature review, experimental results and empirical analysis

    Highlights: • Analyses of polymers thermo-mechanical conditions during FSW. • Application of Arbegast partitioned material flow model. • Analysis of PMMA welds morphology and defects. • Qualitative assessment of residual stress fields. • Temperature distribution during FSW. - Abstract: Meanwhile the thermo-mechanical conditions during Friction Stir Welding (FSW) of metals have already been subject of extensive analysis and thoroughly discussed in literature, in which concerns the FSW of polymers, the information regarding this subject is still very scarce. In this work, an analysis of the material flow and thermo-mechanical phenomena taking place during FSW of polymers is performed. The analysis is based on a literature review and on the examination of friction stir welds, produced under varied FSW conditions, on polymethyl methacrylate (PMMA). Due to the high transparency of this polymer, it was possible to analyse easily the morphological changes induced by the welding process on it. Results of the weld morphologic analysis, of the residual stress fields in the different weld zones and of temperature measurements during welding are shown, and its relation with welding conditions is discussed. From the study it was possible to conclude that, due to the polymers rheological and physical properties, the thermo-mechanical conditions during FSW are very different from that registered during welding of metals, leading to completely different material flow mechanisms and weld defect morphologies

  15. Thermo-mechanical loadings of primary structures in accidental conditions, and approach to solution by limit design

    The static thermo-mechanical loadings of some important structures due to accidental situations are described and the behaviour of these structures is calculated by several methods, elastic and plastic analysis and limit design. The interest of this last method is shown

  16. Lithosphere tectonics and thermo-mechanical properties: An integrated modeling approach for enhanced geothermal systems exploration in Europe

    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 c

  17. Analysis of Dynamic Regimes at Nuclear Power Plants with Fast Reactors Using the JOKER Code

    Seleznev, E.F.; Aizatulin, A.I.; Belov, A.A.; Prianichnikov, A.V.; Fedorov, I.V. [All-Russian Research Institute for NPP Operation (VNIIAES), 25, Ferganskaya str., Moscow, 109507 (Russian Federation); Karpenko, A.I.; Tuchkov, A.M.; Balakhnin, E.V. [Beloyarskaya Nuclear Power Plant (BNPP), BNPP, Zarechnyi, Sverdlovsk region, 624250 (Russian Federation)

    2008-07-01

    To analyze safety of Nuclear Power Plants (NPP) with fast reactors, including studying of different NPP operational modes ranging from normal operation up to hypothetical accidents, a software complex - the JOKER Code [1] - was created simulating the behavior of parameters at BN-type fast reactor under steady-state and transient processes therein through the use of: -reactor core model; and -models of equipment and pipelines of primary, secondary and third circuits of the reactor. The core model contains: a neutron-physical model; a thermal-hydraulics model; and a core thermo-mechanics model. The neutron-physical model is based on the use of spatially distributed kinetics of the core. One-dimensional thermal-hydraulic model with regimes 'before' and 'after' the onset of coolant boiling serves as the thermal-hydraulics model. The thermo-mechanics model includes examination of the behavior of fuel and cladding for the cases of fuel burnup, cracking and melting of both cladding and fuel. The Codes GEFEST (Russia) [2] and SAS-4? (USA) [3] are the JOKER Code's analogues. The GEFEST Code is used at NPP with BN-600 fast reactors to justify safe operation of real fuel loads into reactor installations - mainly for calculations of neutron-physical parameters of the core under steady-state regime; the code has a license of the Russian Supervisory Authority and has been used over many years at Beloyarskaya NPP. The SAS-4? Code developed at ANL (USA) is well known throughout the world as a software complex for analysis of fast reactor projects. (authors)

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

    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/m2. 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 models

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

    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. Second-order two-scale finite element algorithm for dynamic thermo-mechanical coupling problem in symmetric structure

    Li, Zhi-Hui; Ma, Qiang; Cui, Junzhi

    2016-06-01

    The new second-order two-scale (SOTS) finite element algorithm is developed for the dynamic thermo-mechanical coupling problems in axisymmetric and spherical symmetric structures made of composite materials. The axisymmetric structure considered is periodic in both radial and axial directions and homogeneous in circumferential direction. The spherical symmetric structure is only periodic in radial direction. The dynamic thermo-mechanical coupling model is presented and the equivalent compact form is derived. Then, the cell problems, effective material coefficients and the homogenized thermo-mechanical coupling problem are obtained successively by the second-order asymptotic expansion of the temperature increment and displacement. The homogenized material obtained is manifested with the anisotropic property in the circumferential direction. The explicit expressions of the homogenized coefficients in the plane axisymmetric and spherical symmetric cases are given and both the derivation of the analytical solutions of the cell functions and the quasi-static thermoelasticity problems are discussed. Based on the SOTS method, the corresponding finite-element procedure is presented and the unconditionally stable implicit algorithm is established. Some numerical examples are solved and the mutual interaction between the temperature and displacement field is studied under the condition of structural vibration. The computational results demonstrate that the second-order asymptotic analysis finite-element algorithm is feasible and effective in simulating and predicting the dynamic thermo-mechanical behaviors of the composite materials with small periodic configurations in axisymmetric and spherical symmetric structures. This may provide a vital computational tool for analyzing composite material internal temperature distribution and structural deformation induced by the dynamic thermo-mechanical coupling response under strong aerothermodynamic environment.

  1. Construction of Codes for Network Coding

    Elsenhans, Andreas-Stephan; Wassermann, Alfred

    2010-01-01

    Based on ideas of K\\"otter and Kschischang we use constant dimension subspaces as codewords in a network. We show a connection to the theory of q-analogues of a combinatorial designs, which has been studied in Braun, Kerber and Laue as a purely combinatorial object. For the construction of network codes we successfully modified methods (construction with prescribed automorphisms) originally developed for the q-analogues of a combinatorial designs. We then give a special case of that method which allows the construction of network codes with a very large ambient space and we also show how to decode such codes with a very small number of operations.

  2. TIPONLINE Code Table

    National Oceanic and Atmospheric Administration, Department of Commerce — Coded items are entered in the tiponline data entry program. The codes and their explanations are necessary in order to use the data

  3. Balanced Permutation Codes

    Gabrys, Ryan; Milenkovic, Olgica

    2016-01-01

    Motivated by charge balancing constraints for rank modulation schemes, we introduce the notion of balanced permutations and derive the capacity of balanced permutation codes. We also describe simple interleaving methods for permutation code constructions and show that they approach capacity

  4. SEVERO code - user's manual

    This user's manual contains all the necessary information concerning the use of SEVERO code. This computer code is related to the statistics of extremes = extreme winds, extreme precipitation and flooding hazard risk analysis. (A.C.A.S.)

  5. Comparison of thermomechanical calculations for highly non-linear quasistatic drift deformations

    Results of code calculations for the November 14, 1979, Waste Isolation Pilot Plant (WIPP) Code Benchmark Workshop are compared. The results from five different codes (COUPLEFLO, JAC, SANCHO, SPECTROM, and STEALTH) are given for a problem involving the creep closure of an underground drift. The basic features of the codes are summarized and the codes are evaluated in terms of their applicability to WIPP problems. The codes predicted essentially the same response for this problem, and they appear to be nearly equally applicable to problems of this type. Also, a new benchmark problem is suggested along with a more realistic creep model for bedded salt

  6. Unfolding the color code

    Kubica, Aleksander; Yoshida, Beni; Pastawski, Fernando

    2015-01-01

    The topological color code and the toric code are two leading candidates for realizing fault-tolerant quantum computation. Here we show that the color code on a $d$-dimensional closed manifold is equivalent to multiple decoupled copies of the $d$-dimensional toric code up to local unitary transformations and adding or removing ancilla qubits. Our result not only generalizes the proven equivalence for $d=2$, but also provides an explicit recipe of how to decouple independent components of the ...

  7. Experiments to validate computer codes used in the safety assessment of concrete containments

    The safety analysis for the hazardous plants with reinforced and prestressed concrete containments includes the assessment of the containment performance under severe accident loading. Such assessment is normally based on the prediction using computer codes, supported by the measured evidence of small scale experiment. A program of small scale experiments is in progress at AEE Winfrith. The first series included five tests on simple concrete frame specimens for providing the basic response data under static loading. The second series included the test on reinforced concrete slab specimens having the geometry representing steel-lined containment walls. The experiment, the properties of the materials used and the measurement are reported. The selection of the measured results is presented. The validation of the finite element computer codes, ABAQUS and DYNA 3D, by collating with the measured results is in progress. Two aspects of the safety analysis for concrete containments under severe accident loading are the need for computer codes to predict accurately the structural response at re-entrant corners and the integrity of liners. (K.I.)

  8. ELEFANT: a user-friendly multipurpose geodynamics code

    C. Thieulot

    2014-07-01

    Full Text Available A new finite element code for the solution of the Stokes and heat transport equations is presented. It has purposely been designed to address geological flow problems in two and three dimensions at crustal and lithospheric scales. The code relies on the Marker-in-Cell technique and Lagrangian markers are used to track materials in the simulation domain which allows recording of the integrated history of deformation; their (number density is variable and dynamically adapted. A variety of rheologies has been implemented including nonlinear thermally activated dislocation and diffusion creep and brittle (or plastic frictional models. The code is built on the Arbitrary Lagrangian Eulerian kinematic description: the computational grid deforms vertically and allows for a true free surface while the computational domain remains of constant width in the horizontal direction. The solution to the large system of algebraic equations resulting from the finite element discretisation and linearisation of the set of coupled partial differential equations to be solved is obtained by means of the efficient parallel direct solver MUMPS whose performance is thoroughly tested, or by means of the WISMP and AGMG iterative solvers. The code accuracy is assessed by means of many geodynamically relevant benchmark experiments which highlight specific features or algorithms, e.g., the implementation of the free surface stabilisation algorithm, the (visco-plastic rheology implementation, the temperature advection, the capacity of the code to handle large viscosity contrasts. A two-dimensional application to salt tectonics presented as case study illustrates the potential of the code to model large scale high resolution thermo-mechanically coupled free surface flows.

  9. ASME code and ratcheting in piping components. Final technical report

    The main objective of this research is to develop an analysis program which can accurately simulate ratcheting in piping components subjected to seismic or other cyclic loads. Ratcheting is defined as the accumulation of deformation in structures and materials with cycles. This phenomenon has been demonstrated to cause failure to piping components (known as ratcheting-fatigue failure) and is yet to be understood clearly. The design and analysis methods in the ASME Boiler and Pressure Vessel Code for ratcheting of piping components are not well accepted by the practicing engineering community. This research project attempts to understand the ratcheting-fatigue failure mechanisms and improve analysis methods for ratcheting predictions. In the first step a state-of-the-art testing facility is developed for quasi-static cyclic and seismic testing of straight and elbow piping components. A systematic testing program to study ratcheting is developed. Some tests have already been performed and the rest will be completed by summer'99. Significant progress has been made in the area of constitutive modeling. A number of sophisticated constitutive models have been evaluated in terms of their simulations for a broad class of ratcheting responses. From the knowledge gained from this evaluation study two improved models are developed. These models are demonstrated to have promise in simulating ratcheting responses in piping components. Hence, implementation of these improved models in widely used finite element programs, ANSYS and/or ABAQUS, is in progress. Upon achieving improved finite element programs for simulation of ratcheting, the ASME Code provisions for ratcheting of piping components will be reviewed and more rational methods will be suggested. Also, simplified analysis methods will be developed for operability studies of piping components and systems. Some of the future works will be performed under the auspices of the Center for Nuclear Power Plant Structures

  10. Informal control code logic

    Bergstra, J. A.

    2010-01-01

    General definitions as well as rules of reasoning regarding control code production, distribution, deployment, and usage are described. The role of testing, trust, confidence and risk analysis is considered. A rationale for control code testing is sought and found for the case of safety critical embedded control code.

  11. Informal Control code logic

    Bergstra, Jan A.

    2010-01-01

    General definitions as well as rules of reasoning regarding control code production, distribution, deployment, and usage are described. The role of testing, trust, confidence and risk analysis is considered. A rationale for control code testing is sought and found for the case of safety critical embedded control code.

  12. Gauge color codes

    Bombin Palomo, Hector

    2015-01-01

    Color codes are topological stabilizer codes with unusual transversality properties. Here I show that their group of transversal gates is optimal and only depends on the spatial dimension, not the local geometry. I also introduce a generalized, subsystem version of color codes. In 3D they allow the...

  13. ARC Code TI: CODE Software Framework

    National Aeronautics and Space Administration — CODE is a software framework for control and observation in distributed environments. The basic functionality of the framework allows a user to observe a...

  14. ARC Code TI: ROC Curve Code Augmentation

    National Aeronautics and Space Administration — ROC (Receiver Operating Characteristic) curve Code Augmentation was written by Rodney Martin and John Stutz at NASA Ames Research Center and is a modification of...

  15. Thermo-mechanical fatigue behavior of reduced activation ferrite/martensite stainless steels

    The thermo-mechanical cycling fatigue (TMCF) behavior of reduced activation ferrite/martensite stainless steels is examined. The test rig consists of a stiff load frame, which is directly heated by the digitally controlled ohmic heating device. Cylindrical specimens are used with a wall thickness of 0.4 mm. Variable strain rates are applied at TMCF test mode, due to the constant heating rate of 5.8 K/s and variable temperature changes. TMCF results of as received EUROFER 97 in the temperature range between 100 and 500-600 deg. C show a reduction in life time (a factor of 2) compared to F82H mod. and OPTIFER IV. TMCF-experiments with hold times of 100 and 1000 s show dramatic reduction in life time for all three materials

  16. AB INITIO Modeling of Thermomechanical Properties of Mo-Based Alloys for Fossil Energy Conversion

    Ching, Wai-Yim

    2013-12-31

    In this final scientific/technical report covering the period of 3.5 years started on July 1, 2011, we report the accomplishments on the study of thermo-mechanical properties of Mo-based intermetallic compounds under NETL support. These include computational method development, physical properties investigation of Mo-based compounds and alloys. The main focus is on the mechanical and thermo mechanical properties at high temperature since these are the most crucial properties for their potential applications. In particular, recent development of applying ab initio molecular dynamic (AIMD) simulations to the T1 (Mo{sub 5}Si{sub 3}) and T2 (Mo{sub 5}SiB{sub 2}) phases are highlighted for alloy design in further improving their properties.

  17. Third-order thermo-mechanical properties for packs of Platonic solids using statistical micromechanics

    Gillman, A.; Amadio, G.; Matouš, K.; Jackson, T. L.

    2015-01-01

    Obtaining an accurate higher order statistical description of heterogeneous materials and using this information to predict effective material behaviour with high fidelity has remained an outstanding problem for many years. In a recent letter, Gillman & Matouš (2014 Phys. Lett. A 378, 3070–3073. ()) accurately evaluated the three-point microstructural parameter that arises in third-order theories and predicted with high accuracy the effective thermal conductivity of highly packed material systems. Expanding this work here, we predict for the first time effective thermo-mechanical properties of granular Platonic solid packs using third-order statistical micromechanics. Systems of impenetrable and penetrable spheres are considered to verify adaptive methods for computing n-point probability functions directly from three-dimensional microstructures, and excellent agreement is shown with simulation. Moreover, a significant shape effect is discovered for the effective thermal conductivity of highly packed composites, whereas a moderate shape effect is exhibited for the elastic constants.

  18. Thermo-mechanical properties of mixed ion-electron conducting membrane materials

    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

  19. Performance improvement of a micro thermomechanical generator by incorporating Galinstan® micro droplet arrays

    In previous research we have demonstrated a micro thermomechanical pyroelectric generator (µTMPG) as an alternative to thermoelectric generators to harvest ambient heat energy. In such a device, a thermal mass oscillates between a hot and a cold side by virtue of the bistability of its mechanical mount, thus generating a temporal thermal gradient over a pyroelectric material in between. The operational frequency as a major factor deciding the power output of the µTMPG is in turn dependent on the thermal contact resistance (TCR) present at the mating regions of thermal mass, hot and cold sides. Hence, we have investigated the incorporation of an array of Galinstan droplets at the mating interfaces to reduce the TCR. These arrays are fabricated by selective deposition of Galinstan on a laser-micromachined silicon substrate. After incorporating such an array the operational frequency of the µTMPG increases by at least 50%. (paper)

  20. Performance improvement of a micro thermomechanical generator by incorporating Galinstan® micro droplet arrays

    Ravindran, S. K. T.; Roulet, M.; Huesgen, T.; Kroener, M.; Woias, P.

    2012-09-01

    In previous research we have demonstrated a micro thermomechanical pyroelectric generator (µTMPG) as an alternative to thermoelectric generators to harvest ambient heat energy. In such a device, a thermal mass oscillates between a hot and a cold side by virtue of the bistability of its mechanical mount, thus generating a temporal thermal gradient over a pyroelectric material in between. The operational frequency as a major factor deciding the power output of the µTMPG is in turn dependent on the thermal contact resistance (TCR) present at the mating regions of thermal mass, hot and cold sides. Hence, we have investigated the incorporation of an array of Galinstan droplets at the mating interfaces to reduce the TCR. These arrays are fabricated by selective deposition of Galinstan on a laser-micromachined silicon substrate. After incorporating such an array the operational frequency of the µTMPG increases by at least 50%.

  1. Thermo-mechanical cracking of a new and laser repair welded die casting die

    D. Klobčar

    2012-07-01

    Full Text Available The paper presents the analysis of thermo-mechanical fatigue cracking of die casting die during industrial use. An innovative, production friendly approach to monitor the surface crack dimensions was introduced, which is based on measuring defect-fin on the casting part. A new four moulds die casting die was monitored 40 000 cycles in order to complete the production series. The production was stopped three times for laser repair welding of cracks since the defect-fins were not acceptable. The defect-fin heights were measured every 1 000 cycles on the castings before and after repair welding of die surface cracks. The in-service die life can be prolonged with laser repair welding for several times, even thought that in-service die life for a particular repair varies.

  2. Thermomechanical treatment of 2124 PM aluminum alloys with low and high dispersoid levels

    Sarkar, B.; Lisagor, W. B.

    1986-01-01

    The effects of thermomechanical treatment (TMT) on the mechanical properties and metallurgical structure of 2124 powder metallurgy aluminum alloys prepared from rapidly solidified powders were investigated. The alloys were prepared by using a standard canning/vacuum degassing/hot consolidation/extrusion sequence. Two compositions, with manganese contents of 0.5 and 1.5 percent, were investigated to examine the effects of low and high dispersoid levels. The results indicate that significant improvements in strength can be accomplished through TMT for this PM alloy system with little loss in toughness. The increase in strength observed is attributed to the presence of much finer, more homogeneous S-prime precipitation than that observed without TMT. Rolling deformation at room temperature resulted in some tendency for nonuniform (planar) deformation and resulted in slightly lower notch strength values. The lower notch strengths observed in the higher manganese composition were attributed to the coarser, more dense dispersoids observed in this material.

  3. Improvement of thermo-mechanical position stability of the beam position monitor in PLS-II

    Ha, Taekyun; Kwon, Hyuckchae; Han, Hongsik; Park, Chongdo

    2016-01-01

    In the storage ring of PLS-II, we reduced mechanical displacement of electron beam position monitors (e-BPMs) that is caused by heating during e-beam storage. The orbit feedback system intends that the electron beam pass through the center of the BPM, so to provide stable photon beam into beamlines the BPM pickup itself must be stable to sub-micrometer precision. Thermal deformation of the vacuum chambers on which the BPM pickups are mounted is inevitable when the electron beam current is changed by unintended beam abort. We reduced this deformation by improving the vacuum chamber support and by enhancing the water cooling. We report the thermo-mechanical analysis and displacement measurements of BPM pickups after the improvements.

  4. Extrusion as a thermo-mechanical pre-treatment for lignocellulosic ethanol

    Lamsal, B. [Department of Food Science and Human Nutrition, Iowa State University (United States); Yoo, J.; Brijwani, K.; Alavi, S. [Department of Grain Science and Industry, Kansas State University (United States)

    2010-12-15

    Two physical pre-treatment methods, particle size reduction by grinding and thermo-mechanical extrusion, were evaluated as alternatives to traditional biomass pretreatments for lignocellulosic ethanol. Commonly available agricultural co-products wheat bran and soybean hull were the model substrates. Extrusion led to higher reducing sugar yields as compared to grinding for wheat bran, but not in the case of soybean hulls. The best combination of extrusion screw speed and maximum barrel temperature were 7 Hz/150 C and 3.7 Hz/110 C. The use of a solvent mixture (sodium hydroxide, urea, and thiourea) and calcium chloride solution in combination with extrusion treatment did not lead to improvement in reducing sugar yield. However, extensive washing to get rid of solvents and enzymatic inhibitors improved the conversion efficiency substantially, resulting in total reducing sugar yields of 60-73% and 25-36%, respectively, for wheat bran and soybean hull. (author)

  5. On stability of NiTi wire during thermo-mechanical cycling

    C N Saikrishna; K V Ramaiah; S Allam Prabhu; S K Bhaumik

    2009-06-01

    The use of NiTi wire as thermal actuator involves repeated thermal cycling through the transformation range under a constant or fluctuating load. The stability of the material under such conditions has been a concern for the past many years. Experimental results show that for a given alloy composition, the repetitive functional behaviour of NiTi wire is largely dependent on the processing schedule/parameters and the stress–strain regime of thermo-mechanical cycling (TMC). Among the various processing parameters, retained cold work in the material and the shape memory annealing temperature/time have significant influence. It has been shown in the present study that for a stable functional behaviour, the material needs to be tailored through judicious selection of these parameters. Study also shows that, after processing, the material requires an additional stabilization treatment for ensuring minimal variation in the repetitive functional response upon TMC.

  6. Compilation of data for thermomechanical analyses of four potential salt repositories

    This report includes a collection and summarization of the data which are necessary to perform thermomechanical analyses of four potential salt repository sites: Paradox Basin, Utah; Permian Basin, Texas; Richton Dome, Mississippi; and Vacherie Dome, Louisiana. Thermal, mechanical, and hydrogeological material properties are presented so that the numerical analyses can be subdivided into three geometric regions: canister, disposal room, and repository site. Data are presented for the salt formations, the surrounding geological units, and for human-made materials placed in the repository such as the nuclear waste and its protective steel liner. Wherever possible, site-specific data are used which have been determined from laboratory testing of drill core or from interpretation of geophysical logs. Although much effort has been made to obtain the most appropriate data, there are deficiencies because some of the required site-specific data are either not available or are inconsistent with anticipated values

  7. Microstructural characteristic of low carbon microalloyed steels produced by thermo-mechanical controlled process

    The microstructural characteristic of the low carbon microalloyed steels produced by thermo-mechanical controlled processing was investigated by means of optical and transmission electron microscopies. Polygonal ferrite and acicular ferrite were found in OM; under TEM, acicular ferrite with high dislocation density, ultra-fine grain ferrite, layer of thin martensite film and precipitate phase were identified in 560 MPa grade Ti-Nb and Ti-Nb-V microalloyed steels. An ultra-fine dispersion of precipitate phase was also found in Ti-Nb-V steel. These fine-scale microstructures exhibit excellent strength and fracture toughness, which is the main reason that TMCP is widely used in the production of high-strength low-alloy steels

  8. Development of Semantic Description for Multiscale Models of Thermo-Mechanical Treatment of Metal Alloys

    Macioł, Piotr; Regulski, Krzysztof

    2016-06-01

    We present a process of semantic meta-model development for data management in an adaptable multiscale modeling framework. The main problems in ontology design are discussed, and a solution achieved as a result of the research is presented. The main concepts concerning the application and data management background for multiscale modeling were derived from the AM3 approach—object-oriented Agile multiscale modeling methodology. The ontological description of multiscale models enables validation of semantic correctness of data interchange between submodels. We also present a possibility of using the ontological model as a supervisor in conjunction with a multiscale model controller and a knowledge base system. Multiscale modeling formal ontology (MMFO), designed for describing multiscale models' data and structures, is presented. A need for applying meta-ontology in the MMFO development process is discussed. Examples of MMFO application in describing thermo-mechanical treatment of metal alloys are discussed. Present and future applications of MMFO are described.

  9. CHARACTERIZATION OF THERMO-MECHANICAL FATIGUE PROPERTIES FOR PARTICULATE REINFORCED COMPOSITES

    H.J. Shi; H.X. Mei; R. Guo; G. Mesmacque

    2004-01-01

    A Voronoi cell element, formulated with creep, thermal and plastic strain was applied for investigation of thermo-mechanical fatigue behavior for particulate reinforced composites. Under the in-phase fatigue loading, the maximum of tensile deformation at the maximum given loading are larger than that at the same maximum under the out-phase fatigue. The stiffness decreases nonlinearly with the increasing of the phase angle, which results in increasing of the area of fatigue loop curve and the decrease in fatigue life. The spatially centralizing of inclusions results in decreasing of the plastic strain amplitude and the area of fatigue loop curve, which will also reduce the consumption of single-circle plastic strain energy and prolong the fatigue life.

  10. Thermo-mechanical calculations on operation temperature limits of tungsten as plasma facing material

    Tungsten is a candidate material as a plasma facing material in the next step fusion devices. The material surface will be exposed to transient heat loads as well as steady-state heat loads. The present work describes the thermo-mechanical analysis of tungsten by finite element calculation. It is shown that tungsten has a strict operational temperature limit under transient heat loads. For the ITER-grade W, the operation limit of the base surface-temperature was calculated to be in a range of 400-780 deg. C under an applied transient heat load of 0.2 GW/m2 for 0.5 ms in order to avoid plastic deformation of W

  11. Existence result for a class of generalized standard materials with thermomechanical coupling

    Paoli, Laetitia

    2011-01-01

    This paper deals with the study of a three-dimensional model of thermomechanical coupling for viscous solids exhibiting hysteresis effects. This model is written in accordance with the formalism of generalized standard materials and it is composed of the momentum equilibrium equation combined with the flow rule, which describes some stress-strain dependance, coupled to the heat-transfer equation. More precisely, the coupling terms are linear with respect to the temperature and the displacement and non linear with respect to the internal variable. The main mathematical difficulty lies in the fact that the natural framework for the right-hand side of the heat equation is the space of L1 functions. A local existence result for this thermodynamically consistent problem is obtained by using a fixed-point argument. Then the solutions are proved to be physically admissible and global existence is discussed under some additional assumptions on the data.

  12. Data Buoy powered by a thermo-mechanical generator: results of a year's operation at sea

    The UK National Data Buoy is powered by a prototype thermo-mechanical generator. This power source delivers 20 to 25 watts electrical and requires several times less fuel than an equivalent propane-heated thermo-electric power source, so that fuel for 21/2 years' operation can be carried on the Buoy. The Buoy has been stationed in the North Sea off the East Coast of England since December 1975, and operating experience with the TMG in the succeeding year is described. Such problems as have been encountered have been mainly peripheral in nature, and the TMG has been running for about 90 percent of the maximum time possible. Operating experience with other similar generators are discussed, and recent development of a 60W TMG is outlined

  13. A numerical study of crack interactions under thermo-mechanical load using EFGM

    In this work, element free Galerkin method (EFGM) has been used to obtain the solution of various edge crack problems under thermo-mechanical loads as it provides a versatile technique to model stationary as well as moving crack problems without re-meshing. Standard diffraction criterion has been modified with multiple crack weight technique to characterize the presence of various cracks in the domain of influence of a particular node. The effect of crack inclination has been studied for single as well as two edge cracks, whereas the cracks interaction has been studied for two edge cracks lying on same as well as opposite edges under plane stress conditions. The values of mode-I and mode-II stress intensity factors have been evaluated by the interaction integral approach

  14. Nonlinear thermomechanical deformation behaviour of P-FGM shallow spherical shell panel

    Vishesh Ranjan Kar

    2016-02-01

    Full Text Available In the present article, the linear and the nonlinear deformation behaviour of functionally graded (FG spherical shell panel are examined under thermomechanical load. The temperature-dependent effective material properties of FG shell panel are evaluated using Voigt’s micro-mechanical rule in conjunction with power-law distribution. The nonlinear mathematical model of the FG shell panel is developed based on higher-order shear deformation theory and Green-Lagrange type geometrical nonlinearity. The desired nonlinear governing equation of the FG shell panel is computed using the variational principle. The model is discretised through suitable nonlinear finite element steps and solved using direct iterative method. The convergence and the validation behaviour of the present numerical model are performed to show the efficacy of the model. The effect of different parameters on the nonlinear deformation behaviour of FG spherical shell panel is highlighted by solving numerous examples.

  15. Modeling of the thermo-mechanical efficiency of the bimetal strip heat engines

    This paper presents a theoretical demonstration of the bimetal strip heat engine working, based on the study of the thermo-mechanical instability of the pre-buckled bimetallic beams. Starting from the Euler buckling equation, this paper describes the bimetal strips like classical but non-linear thermodynamic systems, and gives the bistability criterion of such beams. Studying the thermodynamic potentials of these beams helps to evaluate the release of the kinetic energy happening during the beam snap-through, to give the Maxwell relations between each partial derivative of the thermodynamic potentials and to show that the thermal snap-through is a first-order transition according to the Ehrenfest theory. The model is then used to draw the temperature-entropy cycle of the bimetal heat engines and to evaluate the performances of these harvesters (available mechanical energy and thermodynamic cycle efficiency)

  16. Effect of thermo-mechanical properties of PIM feedstock on compacts shape retention during debinding process

    2001-01-01

    The removal of the binder from the powder compacts (debinding) can be a slow step and a source of problems. To improve the debinding process of powder injection molding operation, it's necessary to understand the thermal and mechanical properties of powder injection molding feedstocks and to find the major causes responsible for molding difficulties and compacts shape retention during debinding process. The effects of thermo-mechanical properties of the PIM feedstock on the compacts shape retention during debinding process were discussed and explained from practical point of view. The results indicate that the heat of fusion affects the cooling time. The binder component with high heat of fusion and high-decomposed temperature is more effective as the second binder component for the compact to retain its shape during debinding.

  17. Modelling the thermo-mechanical volume change behaviour of compacted expansive clays

    Tang, Anh-Minh; 10.1680/geot.2009.59.3.185

    2009-01-01

    Compacted expansive clays are often considered as a possible buffer material in high-level deep radioactive waste disposals. After the installation of waste canisters, the engineered clay barriers are subjected to thermo-hydro-mechanical actions in the form of water infiltration from the geological barrier, heat dissipation from the radioactive waste canisters, and stresses generated by clay swelling under almost confined conditions. The aim of the present work is to develop a constitutive model that is able to describe the behaviour of compacted expansive clays under these coupled thermo-hydro-mechanical actions. The proposed model is based on two existing models: one for the hydro-mechanical behaviour of compacted expansive clays and another for the thermo-mechanical behaviour of saturated clays. The elaborated model has been validated using the thermo-hydro-mechanical test results on the compacted MX80 bentonite. Comparison between the model prediction and the experimental data show that this model is able...

  18. Dynamic-mechanical and thermomechanical properties of cellulose nanofiber/polyester resin composites.

    Lavoratti, Alessandra; Scienza, Lisete Cristine; Zattera, Ademir José

    2016-01-20

    Composites of unsaturated polyester resin (UPR) and cellulose nanofibers (CNFs) obtained from dry cellulose waste of softwood (Pinus sp.) and hardwood (Eucalyptus sp.) were developed. The fiber properties and the influence of the CNFs in the dynamic-mechanical and thermomechanical properties of the composites were evaluated. CNFs with a diameter of 70-90 nm were obtained. Eucalyptus sp. has higher α-cellulose content than Pinus sp. fibers. The crystallinity of the cellulose pulps decreased after grinding. However, high values were still obtained. The chemical composition of the fibers was not significantly altered by the grinding process. Eucalyptus sp. CNF composites had water absorption close to the neat resin at 1 wt% filler. The dynamic-mechanical properties of Eucalyptus sp. CNFs were slightly increased and the thermal stability was improved. PMID:26572434

  19. Thermo-Mechanical tests for the CLIC two-beam module study

    Xydou, A; Riddone, G; Daskalaki, E

    2014-01-01

    The luminosity goal of CLIC requires micron level precision with respect to the alignment of the components on its two-meter long modules, composing the two main linacs. The power dissipated inside the module components introduces mechanical deformations affecting their alignment and therefore the resulting machine performance. Several two-beam prototype modules must be assembled to extensively measure their thermo-mechanical behavior under different operation modes. In parallel, the real environmental conditions present in the CLIC tunnel should be studied. The air conditioning and ventilation system providing specified air temperature and flow has been installed in the dedicated laboratory. The power dissipation occurring in the modules is being reproduced by the electrical heaters inserted inside the RF structure mock-ups and the quadrupoles. The efficiency of the cooling systems is being verified and the alignment of module components is monitored. The measurement results will be compared to finite elemen...

  20. Thermomechanical analysis of thin films on temperature-dependent elastomeric substrates in flexible heterogeneous electronics

    Thermomechanical analysis is presented to study the basic temperature effects on elastomeric substrate of flexible electronics. Strains of a films-on-substrate structure related with three key temperatures are given based on the interfacial continuum model. An improved strain model is given and compared with other two models. The role of the temperature-dependent effects is highlighted and adopted to design a flexible inorganic/organic heterogeneous structure subject to little thermal action. The sensitivity analysis of three key temperatures is investigated, by which proper selection of technological parameter for poly(dimethylsiloxane) fabrication may be determined to eliminate the variation of stress of the interface in circumstances with temperature varying severely. This work contributes to systemic reliability and compatibility, structural design and thermal management of flexible electronics.

  1. Effect of thermomechanical treatment on 9Cr ferritic–martensitic steels

    Tan, L., E-mail: tanl@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory (United States); Busby, J.T.; Maziasz, P.J.; Yamamoto, Y. [Materials Science and Technology Division, Oak Ridge National Laboratory (United States)

    2013-10-15

    High-Cr (9 wt.%) ferritic–martensitic steels are important materials for use in nuclear reactors. This study shows a development activity for this category of steels via thermomechanical treatment (TMT) optimization and alloying element adjustment based on Grade 92 steels. Vickers microhardness and tensile tests were employed to assess the mechanical properties of the materials in the normalized-tempered (N and T) and optimized TMT conditions. The treatment of one of the modified heats produced ∼29% and ∼47% increases in hardness and yield strength, respectively, compared to the Grade 92 in the N and T condition. The TMT-treated alloys showed comparable or superior strength relative to the oxide-dispersion-strengthened steel PM2000. Microstructure analyses by optical and transmission electron microscopy together with thermodynamic calculations identified the strengthening mechanisms of the TMT and precipitates.

  2. Thermomechanical treatment for improved neutron irradiation resistance of austenitic alloy (Fe–21Cr–32Ni)

    An optimized thermomechanical treatment (TMT) applied to austenitic alloy 800H (Fe–21Cr–32Ni) had shown significant improvements in corrosion resistance and basic mechanical properties. This study examined its effect on radiation resistance by irradiating both the solution-annealed (SA) and TMT samples at 500 °C for 3 dpa. Microstructural characterization using transmission electron microscopy revealed that the radiation-induced Frank loops, voids, and γ′-Ni3(Ti,Al) precipitates had similar sizes between the SA and TMT samples. The amounts of radiation-induced defects and more significantly γ′ precipitates, however, were reduced in the TMT samples. These reductions would approximately reduce by 40.9% the radiation hardening compared to the SA samples. This study indicates that optimized-TMT is an economical approach for effective overall property improvements

  3. Effect of thermomechanical treatment on 9Cr ferritic–martensitic steels

    High-Cr (9 wt.%) ferritic–martensitic steels are important materials for use in nuclear reactors. This study shows a development activity for this category of steels via thermomechanical treatment (TMT) optimization and alloying element adjustment based on Grade 92 steels. Vickers microhardness and tensile tests were employed to assess the mechanical properties of the materials in the normalized-tempered (N and T) and optimized TMT conditions. The treatment of one of the modified heats produced ∼29% and ∼47% increases in hardness and yield strength, respectively, compared to the Grade 92 in the N and T condition. The TMT-treated alloys showed comparable or superior strength relative to the oxide-dispersion-strengthened steel PM2000. Microstructure analyses by optical and transmission electron microscopy together with thermodynamic calculations identified the strengthening mechanisms of the TMT and precipitates

  4. Thermomechanical treatment for improved neutron irradiation resistance of austenitic alloy (Fe-21Cr-32Ni)

    An optimized thermomechanical treatment (TMT) applied to austenitic alloy 800H (Fe-21Cr-32Ni) had shown significant improvements in corrosion resistance and basic mechanical properties. This study examined its effect on radiation resistance by irradiating both the solution-annealed (SA) and TMT samples at 500 deg C for 3 dpa. Microstructural characterization using transmission electron microscopy revealed that the radiation-induced Frank loops, voids, and y'-Ni3(Ti,Al) precipitates had similar sizes between the SA and TMT samples. The amounts of radiation-induced defects and more significantly y' precipitates, however, were reduced in the TMT samples. These reductions would approximately reduce by 40.9% the radiation hardening compared to the SA samples. This study indicates that optimized-TMT is an economical approach for effective overall property improvements.

  5. Structure-property relationships in thermomechanically treated beryllia dispersed nickel alloys

    BeO dispersed nickel alloys, produced by powder metallurgy techniques, were studied extensively in stress rupture at 815, 982, and 10930C (1088, 1255, and 1366 K) and by transmission electron microscopy. The alloys were subjected to a variety of thermomechanical treatments (TMT) to determine the benefits of TMT on properties. It is shown that the use of intermediate annealing treatments after 10 percent reduction steps is highly beneficial on both low and high temperature properties. It is indicated that the high temperature strength is not primarily dependent on the grain aspect ratio or texture but depends strongly on the dislocation density and distribution of dislocations in a stable substructure which is pinned by the fine oxide dispersion. (22 fig) (U.S.)

  6. Thermomechanical treatment for improved neutron irradiation resistance of austenitic alloy (Fe-21Cr-32Ni)

    L. Tan; J. T. Busby; H. J. M. Chichester; K. Sridharan; T. R. Allen

    2013-06-01

    An optimized thermomechanical treatment (TMT) applied to austenitic alloy 800H (Fe-21Cr-32Ni) had shown significant improvements in corrosion resistance and basic mechanical properties. This study examined its effect on radiation resistance by irradiating both the solution-annealed (SA) and TMT samples at 500 degrees C for 3 dpa. Microstructural characterization using transmission electron microscopy revealed that the radiation-induced Frank loops, voids, and y'-Ni3(Ti,Al) precipitates had similar sizes between the SA and TMT samples. The amounts of radiation-induced defects and more significantly y' precipitates, however, were reduced in the TMT samples. These reductions would approximately reduce by 40.9% the radiation hardening compared to the SA samples. This study indicates that optimized-TMT is an economical approach for effective overall property improvements.

  7. New nano-particle-strengthened ferritic/martensitic steels by conventional thermo-mechanical treatment

    For increased fusion power plant efficiency, steels for operation at 650 oC and higher are sought. Based on the science of precipitate strengthening, a thermo-mechanical treatment (TMT) was developed that increased the strength from room temperature to 700 oC of commercial nitrogen-containing steels and new steels designed for the TMT. At 700 oC increases in yield stress of 80 and 200% were observed for a commercial steel and a new steel, respectively, compared to commercial normalized-and-tempered steels. Creep-rupture strength was similarly improved. Depending on the TMT, precipitates were up to eight-times smaller at a number density four orders of magnitude greater than those in a conventionally heat treated steel of similar composition

  8. Thermomechanical treatment for improved neutron irradiation resistance of austenitic alloy (Fe–21Cr–32Ni)

    Tan, L., E-mail: tanl@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Busby, J.T. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Chichester, H.J.M. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Sridharan, K.; Allen, T.R. [University of Wisconsin, Madison, WI 53706 (United States)

    2013-06-15

    An optimized thermomechanical treatment (TMT) applied to austenitic alloy 800H (Fe–21Cr–32Ni) had shown significant improvements in corrosion resistance and basic mechanical properties. This study examined its effect on radiation resistance by irradiating both the solution-annealed (SA) and TMT samples at 500 °C for 3 dpa. Microstructural characterization using transmission electron microscopy revealed that the radiation-induced Frank loops, voids, and γ′-Ni{sub 3}(Ti,Al) precipitates had similar sizes between the SA and TMT samples. The amounts of radiation-induced defects and more significantly γ′ precipitates, however, were reduced in the TMT samples. These reductions would approximately reduce by 40.9% the radiation hardening compared to the SA samples. This study indicates that optimized-TMT is an economical approach for effective overall property improvements.

  9. Influence of Carbon Nano Tubes on the Thermo-Mechanical Properties of Unsaturated Polyester Nanocomposite

    Moshiul Alam, A. K. M.; Beg, M. D. H.; Mohd Yunus, Rosli

    2015-04-01

    To date nano fillers are renowned reinforcing agent for polymer materials. In this work, unsaturated polyester (UPR) nanocomposites were fabricated by 0.1, 0.3 and 0.5 wt% multi walled carbon nanotubes (MWCNTs) through solution dispersion and casting method. The influence of MWCNT content was investigated by thermo-mechanical properties. Dispersion of nanotubes was observed by fracture morphology. The strength of nanocomposites rose with raising the CNT content. Moreover, DSC thermograms of nanocomposites represent noticeable improvement of glass transition temperature (Tg), melting temperature (Tm) and enthalpy (ΔHm). Micro-crystallinity of nanocomposites increased with increasing the CNT content. Moreover, the stiffness increased with increasing the CNT content.

  10. Energy-based fatigue model for shape memory alloys including thermomechanical coupling

    Zhang, Yahui; Zhu, Jihong; Moumni, Ziad; Van Herpen, Alain; Zhang, Weihong

    2016-03-01

    This paper is aimed at developing a low cycle fatigue criterion for pseudoelastic shape memory alloys to take into account thermomechanical coupling. To this end, fatigue tests are carried out at different loading rates under strain control at room temperature using NiTi wires. Temperature distribution on the specimen is measured using a high speed thermal camera. Specimens are tested to failure and fatigue lifetimes of specimens are measured. Test results show that the fatigue lifetime is greatly influenced by the loading rate: as the strain rate increases, the fatigue lifetime decreases. Furthermore, it is shown that the fatigue cracks initiate when the stored energy inside the material reaches a critical value. An energy-based fatigue criterion is thus proposed as a function of the irreversible hysteresis energy of the stabilized cycle and the loading rate. Fatigue life is calculated using the proposed model. The experimental and computational results compare well.

  11. Thermomechanical properties of the coil of the superconducting magnets for the Large Hadron Collider

    Couturier, K; Scandale, Walter; Todesco, Ezio; Tommasini, D

    2002-01-01

    The correct definition and measurement of the thermomechanical properties of the superconducting cable used in high-field magnets is crucial to study and model the behavior of the magnet coil from assembly to the operational conditions. In this paper, the authors analyze the superconducting coil of the main dipoles for the Large Hadron Collider. They describe an experimental setup for measuring the elastic modulus at room and at liquid nitrogen temperature and for evaluating the thermal contraction coefficient. The coils exhibit strong nonlinear stress-strain behavior characterized by hysteresis phenomena, which decreases from warm to cold temperature, and a thermal contraction coefficient, which depends on the stress applied to the cable during cooldown. (35 refs).

  12. Probing thermomechanics at the nanoscale: impulsively excited pseudosurface acoustic waves in hypersonic phononic crystals.

    Nardi, Damiano; Travagliati, Marco; Siemens, Mark E; Li, Qing; Murnane, Margaret M; Kapteyn, Henry C; Ferrini, Gabriele; Parmigiani, Fulvio; Banfi, Francesco

    2011-10-12

    High-frequency surface acoustic waves can be generated by ultrafast laser excitation of nanoscale patterned surfaces. Here we study this phenomenon in the hypersonic frequency limit. By modeling the thermomechanics from first-principles, we calculate the system's initial heat-driven impulsive response and follow its time evolution. A scheme is introduced to quantitatively access frequencies and lifetimes of the composite system's excited eigenmodes. A spectral decomposition of the calculated response on the eigemodes of the system reveals asymmetric resonances that result from the coupling between surface and bulk acoustic modes. This finding allows evaluation of impulsively excited pseudosurface acoustic wave frequencies and lifetimes and expands our understanding of the scattering of surface waves in mesoscale metamaterials. The model is successfully benchmarked against time-resolved optical diffraction measurements performed on one-dimensional and two-dimensional surface phononic crystals, probed using light at extreme ultraviolet and near-infrared wavelengths. PMID:21910426

  13. Thermo-mechanical optimization of Fixed Mask 2 for APS front ends

    Fixed mask 2 (FM2) is one of the critical elements on the front end of the beamlines at the Advanced Photon Source (APS) now under construction at Argonne National Laboratory (ANL). The FM2 uses an enhanced heat transfer tube developed at ANL. Due to large thermal loads on these components, inclined geometry is used in the design to spread the footprint of the x-ray beam. Even then, thermal loads are very critical. To address the thermal and thermo-mechanical issues, analytical studies have been applied to a simplified model of the FM2 tube. The maximum temperature and maximum effective stress have been parametrically studied. Results for maximum temperatures and stresses are obtained and compared with the available strength/fatigue data for the materials proposed for the fixed mask design

  14. Cytotoxicity and thermomechanical behavior of biomedical shape-memory polymer networks post-sterilization

    Shape-memory polymers (SMPs) are being increasingly proposed for use in biomedical devices. This paper investigates the cytotoxicity, surface characteristics and thermomechanics of two acrylate-based SMP networks as a function of sterilization using a minimal essential media elution test, FTIR-ATR and dynamic mechanical analysis (DMA). Networks sterilized by low-temperature plasma elicited a cytotoxic response and are shown to completely destroy the cell monolayer. FTIR-ATR analysis showed evidence of surface oxidation with an increase and broadening of the absorbance peak from ∼3500 to 3100 cm-1, which is associated with an increase in hydroxyl groups. DMA revealed small, but statistically significant, differences in reduction of the glass transition temperatures of both networks when sterilized with gamma irradiation. One network showed an increase in rubbery modulus, which is an indication of crosslink density, after gamma irradiation. Lastly, practical sterilization concerns of SMP devices are discussed in light of the different methods

  15. Nonlinear thermomechanical deformation behaviour of P-FGM shallow spherical shell panel

    Vishesh Ranjan Kar; Subrata Kumar Panda

    2016-01-01

    In the present article, the linear and the nonlinear deformation behaviour of functionally graded (FG) spherical shell panel are examined under thermomechanical load. The temperature-dependent effective material properties of FG shell panel are evaluated using Voigt’s micro-mechanical rule in conjunction with power-law distribution. The nonlinear mathematical model of the FG shell panel is developed based on higher-order shear deformation theory and Green-Lagrange type geometrical nonlinearity. The desired nonlinear governing equation of the FG shell panel is computed using the variational principle. The model is discretised through suitable nonlinear finite element steps and solved using direct iterative method. The convergence and the val-idation behaviour of the present numerical model are performed to show the efficacy of the model. The effect of different parameters on the nonlinear deformation behaviour of FG spherical shell panel is highlighted by solving numerous examples.

  16. Thermo-mechanical analysis of high level nuclear wastes in granite

    In order to appraise the safety of a storage of high level nuclear wastes in rock masses, it is necessary to assess, among other features, the thermo-mechanical behaviour of the host rock for long periods (thousands of years). In France, four different media are considered as potential host rocks: granite, shale, salt, clay. The present paper is devoted to some analysis of a generic storage configuration in granite. The case of a rock mass without any major fault has been considered. The granite is modelled by means of an elastic fracturing model (no tension type). The results obtained show that some fissures, induced by the heat generation, develop mainly above the repository. The opening of the fissures, within the frame of the adopted hypothesis, have not a strong influence on the rock mass, as a geological barrier for the radionuclides. (author)

  17. Modeling of mechanical behaviour of HSLA low carbon bainitic steel thermomechanically processed

    Santos, D. B.; Rodrigues, P. C. M.; Cota, A. B.

    2003-10-01

    A comparative study of the microstructure characterization and mechanical properties was done in a HSLA low carbon (0.08%) bainitic steel containing boron, developed by industry as a bainitic steel grade APIX80. The steel was submitted to two different thermomechanical processes. In the first one, controlled rolling followed by accelerated cooling was applied in laboratory mill. In the second processing, specimens of the same steel were submitted to hot torsion testing. The influence of cooling conditions like start cooling temperature, cooling rates and finish cooling temperature on the microstructure and mechanical properties were investigated. The final microstructure obtained was a complex mixture of polygonal ferrite, perlite, bainite and martensite/retained austenite constituent. The use of multiple regression analysis allowed the establishment of quantitative relationships between the accelerated cooling variables and mechanical properties of the steel available from Vickers microhardness and tensile tests.

  18. The principles of burying radioactive waste: basic physical and thermomechanical properties of geological formations

    After a review of the various types of radioactive wastes (short and long lives), the principles of radioactive waste storage in geologic structures are detailed: water is the main vector of migration so radionuclides are buried at depth within a medium of very low permeability and hydraulic gradient; the geological medium must retain its integrity during all the duration of their activity; its very age is obviously the guarantee of its future, but tectonic movements, erosion, climate must not deteriorate it in any way nor break down its structure. The thermomechanical effects are examined for each host medium such as plastic media (salt, clay) and brittle media (granite, shale) with an estimation of the long term and very long term rheological properties. 4 figs., 1 tab., 21 refs

  19. Thermomechanical effect of pulse-periodic laser radiation on cartilaginous and eye tissues

    This paper is devoted to theoretical and experimental studies into the thermomechanical action of laser radiation on biological tissues. The thermal stresses and strains developing in biological tissues under the effect of pulse-periodic laser radiation are theoretically modeled for a wide range of laser pulse durations. The models constructed allow one to calculate the magnitude of pressures developing in cartilaginous and eye tissues exposed to laser radiation and predict the evolution of cavitation phenomena occurring therein. The calculation results agree well with experimental data on the growth of pressure and deformations, as well as the dynamics of formation of gas bubbles, in the laser-affected tissues. Experiments on the effect of laser radiation on the trabecular region of the eye in minipigs demonstrated that there existed optimal laser irradiation regimens causing a substantial increase in the hydraulic permeability of the radiation-exposed tissue, which can be used to develop a novel glaucoma treatment method. (paper)

  20. RENEWAL OF BASIC LAWS AND PRINCIPLES FOR POLAR CONTINUUM THEORIES (Ⅴ)-POLAR THERMOMECHANICAL CONTINUA

    戴天民

    2003-01-01

    The purpose is to reestablish rather complete basic balance equations and boundary conditions for polar thermomechanical continua based on the restudy of the traditional theories of micropolar thermoelasticity and thermopiezoelectricity. The equations of motion and the local balance equation of energy rate for micropolar thermoelasticity are derived from the rather complete principle of virtual power. The equations of motion, the balance equation of entropy and all boundary conditions are derived from the rather complete Hamilton principle. The new balance equations of momentum and energy rate which are essentially different from the existing results are presented. The corresponding results of micromorphic thermoelasticity and couple stress elastodynamics may be naturally obtained by the transition and the reduction from the micropolar case, respectively. Finally, the results of micropolar thermopiezoelectricity are directly given.

  1. A thermo-mechanically coupled finite strain model considering inelastic heat generation

    Dunić, Vladimir; Busarac, Nenad; Slavković, Vukašin; Rosić, Bojana; Niekamp, Rainer; Matthies, Hermann; Slavković, Radovan; Živković, Miroslav

    2016-07-01

    The procedure for reuse of finite element method (FEM) programs for heat transfer and structure analysis to solve advanced thermo-mechanical problems is presented as powerful algorithm applicable for coupling of other physical fields (magnetic, fluid flow, etc.). In this case, nonlinear Block-Gauss-Seidel partitioned algorithm strongly couples the heat transfer and structural FEM programs by a component-based software engineering. Component template library provides possibility to exchange the data between the components which solve the corresponding subproblems. The structural component evaluates the dissipative energy induced by inelastic strain. The heat transfer component computes the temperature change due to the dissipation. The convergence is guaranteed by posing the global convergence criterion on the previously locally converged coupled variables. This enables reuse of software and allows the numerical simulation of thermo-sensitive problems.

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

    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)

  3. Thermo-mechanical design of a CW sweep plate emittance scanner

    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)

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

    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

  5. Decomposition and Precipitation Process During Thermo-mechanical Fatigue of Duplex Stainless Steel

    Weidner, Anja; Kolmorgen, Roman; Kubena, Ivo; Kulawinski, Dirk; Kruml, Tomas; Biermann, Horst

    2016-05-01

    The so-called 748 K (475 °C) embrittlement is one of the main drawbacks for the application of ferritic-austenitic duplex stainless steels (DSS) at higher temperatures caused by a spinodal decomposition of the ferritic phase. Thermo-mechanical fatigue tests performed on a DSS in the temperature range between 623 K and 873 K (350 °C and 600 °C) revealed no negative influence on the fatigue lifetime. However, an intensive subgrain formation occurred in the ferritic phase, which was accompanied by formation of fine precipitates. In order to study the decomposition process of the ferritic grains due to TMF testing, detailed investigations using scanning and transmission electron microscopy are presented. The nature of the precipitates was determined as the cubic face centered G-phase, which is characterized by an enrichment of Si, Mo, and Ni. Furthermore, the formation of secondary austenite within ferritic grains was observed.

  6. Reconsideration of Criteria and Modeling in Order to Optimize the Efficiency of Irreversible Thermomechanical Heat Engines

    Michel Feidt

    2010-12-01

    Full Text Available The purpose of this work is to precise and complete one recently proposed in the literature and relative to a general criterion to maximize the first law efficiency of irreversible heat engines. It is shown that the previous proposal seems to be a particular case. A new proposal has been developed for a Carnot irreversible thermomechanical heat engine at steady state associated to two infinite heat reservoirs (hot source, and cold sink: this constitutes the studied system. The presence of heat leak is accounted for, with the most simple form, as is done generally in the literature. Irreversibility is modeled through , created internal entropy rate in the converter (engine, and , total created entropy rate in the system. Heat transfer laws are represented as general functions of temperatures. These concepts are particularized to the most common heat transfer law (linear one. Consequences of the proposal are examined; some new analytical results are proposed for efficiencies.

  7. Thermomechanical effect of pulse-periodic laser radiation on cartilaginous and eye tissues

    Baum, O. I.; Zheltov, G. I.; Omelchenko, A. I.; Romanov, G. S.; Romanov, O. G.; Sobol, E. N.

    2013-08-01

    This paper is devoted to theoretical and experimental studies into the thermomechanical action of laser radiation on biological tissues. The thermal stresses and strains developing in biological tissues under the effect of pulse-periodic laser radiation are theoretically modeled for a wide range of laser pulse durations. The models constructed allow one to calculate the magnitude of pressures developing in cartilaginous and eye tissues exposed to laser radiation and predict the evolution of cavitation phenomena occurring therein. The calculation results agree well with experimental data on the growth of pressure and deformations, as well as the dynamics of formation of gas bubbles, in the laser-affected tissues. Experiments on the effect of laser radiation on the trabecular region of the eye in minipigs demonstrated that there existed optimal laser irradiation regimens causing a substantial increase in the hydraulic permeability of the radiation-exposed tissue, which can be used to develop a novel glaucoma treatment method.

  8. The Procions` code; Le code Procions

    Deck, D.; Samba, G.

    1994-12-19

    This paper presents a new code to simulate plasmas generated by inertial confinement. This multi-kinds kinetic code is done with no angular approximation concerning ions and will work in plan and spherical geometry. First, the physical model is presented, using Fokker-Plank. Then, the numerical model is introduced in order to solve the Fokker-Plank operator under the Rosenbluth form. At the end, several numerical tests are proposed. (TEC). 17 refs., 27 figs.

  9. Effect of Technical Quality of Thermomechanical Die Forging of AA2099 Alloy

    Łukaszek-Sołek A.

    2014-10-01

    Full Text Available The paper presents the results of investigations of a multicomponent third-generation aluminium alloy, classified as AA2099. The actual forging conditions were determined basing on the assessment of the quality of side surface of specimens subjected to compression in Gleeble 3800 simulator and on flow curves of the alloy, as well as numerical modelling of forging process performed with application of QForm 3D v.7 software. Compression tests were realized at temperatures 400-500 °C, with a strain rate of 0.001-100 s-1, up to a specified constant true strain value of 0.9. Microstructure examination in as-delivered state was performed with application of Leica DM 4000M optical microscope. The obtained results of isothermal deformation of specimens were correlated with the analysis of a characteristic layered pancake-type microstructure. The simulation of die forging of a complex-shape forging (high-current contact tip used in power engineering at the temperature 500 °C, was performed. The shape of a forging makes it possible to fully analyse the influence of thermomechanical process conditions on technical quality of a product. The simulation of forging process showed full correctness of material flow, with no signs of instability. At the same time, the analysis of investigations allowed to prepare and realize the industrial forging trials for a forging of a very complex shape, in a single step, at the temperature 500 °C, with application of thermomechanical treatment. The forging attained high quality of shape and surface. Directional specimens were taken, in order to be subjected to microstructure examination and hardness testing. The data obtained from industrial tests, combined with the results of testing using Gleeble simulator as well as from numerical modelling, make up the guidelines for mechanical processing of AA2099 alloy at the temperatures 470-500 °C.

  10. Thermo-mechanical tests on W7-X current lead flanges

    Dhard, Chandra Prakash, E-mail: dhard@ipp.mpg.de; Rummel, Thomas; Zacharias, Daniel; Bykov, Victor; Moennich, Thomas; Buscher, Klaus-Peter

    2013-10-15

    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.

  11. Influence of subsolvus thermomechanical processing on the low-cycle fatigue properties of haynes 230 alloy

    Vecchio, Kenneth S.; Fitzpatrick, Michael D.; Klarstrom, Dwaine

    1995-03-01

    Strain-controlled low-cycle fatigue tests have been conducted in air at elevated temperature to determine the influence of subsolvus thermomechanical processing on the low-cycle fatigue (LCF) behavior of HAYNES 230 alloy. A series of tests at various strain ranges was conducted on material experimentally processed at 1121 °C, which is below the M23C6 carbide solvus temperature, and on material fully solution annealed at 1232 °C. A comparative strain-life analysis was performed on the LCF results, and the cyclic hardening/softening characteristics were examined. At 760 °C and 871 °C, the fatigue life of the experimental 230/1121 material was improved relative to the standard 230/1232 material up to a factor of 3. The fatigue life advantage of the experimental material was related primarily to a lower plastic (inelastic) strain amplitude response for a given imposed total strain range. It appears the increase in monotonic flow stress exhibited by the finer grain size experimental material has been translated into an increase in cyclic flow stress at the 760 °C and 871 °C test temperatures. Both materials exhibited entirely transgranular fatigue crack initiation and propagation modes at these temperatures. The LCF performance of the experimental material in tests performed at 982 °C was improved relative to the standard material up to a factor as high as 2. The life advantage of the 230/1121 material occurred despite having a larger plastic strain amplitude than the standard 230/1232 material for a given total strain range. Though not fully understood at present, it is suspected that this behavior is related to the deleterious influence of grain boundaries in the fatigue crack initiations of the standard processed material relative to the experimental material, and ultimately to differences in carbide morphology as a result of thermomechanical processing.

  12. Thermomechanics-based nonlinear rate-dependent coupled damage-plasticity granular micromechanics model

    Misra, Anil; Singh, Viraj

    2015-09-01

    Thermomechanics and granular micromechanics approaches are combined to derive constitutive equations for modeling rate-dependent granular materials with damage and plasticity. The derivation is motivated by the recognition that the effect of micro-scale mechanisms upon the macro-scale behavior is known to be significant for granular materials. A general thermomechanical framework applicable to rate-dependent granular materials with damage and plasticity is developed. Based upon this framework, an expression for macro-scale Cauchy stress tensor is obtained in terms of the micro-scale grain interaction forces and the relationship between micro- and macro-scale kinematics. In addition, a Clausius-Duhem type inequality applicable to inter-granular interaction is derived, which is used to establish micro-scale constitutive relations for particular type of inter-granular interactions. The expression for Cauchy stress tensor and the micro-scale constitutive relations is then combined under a mean field kinematic assumption to obtain evolution-type macro-scale constitutive equations. The advantage of the granular micromechanics approach is that the damage and plasticity are defined using simple 1d functions at micro-scale, and complicated plastic potentials, damage functions and rules for their evolution are not required. The resultant model is applied to investigate primary, secondary and tertiary creep, creep-recovery as well as rate-dependent response under uniaxial compressive loading. Model applicability is also demonstrated for asymmetric tensile-compressive response under creep-recovery loading. The model is used to evaluate the evolution of elastic energy, and viscous, plastic and damage dissipation at the macro- and micro-scale with respect to creep time and loading level. The results show the development of loading-induced anisotropy due to damage and plasticity in these materials.

  13. Thermo-mechanical correlations to erosion performance of short carbon fibre reinforced vinyl ester resin composites

    Research highlights: → Composite with 30 wt.% of short carbon fibres exhibit highest energy dissipation. → Optimum erosion resistance conditions have been found. → A direct correlation emerged between erosive wear rate and loss-modulus inverse. → Mechanistic equivalence between erosion and dynamic loading modes is established. -- Abstract: Thermo-mechanical properties and erosion performance of short carbon fibre reinforced vinyl ester resin based isotropic polymer composites with four different fibre weight fractions have been investigated. The storage, loss and damping characteristics were analysed to assess the energy absorption/viscous recoverable energy dissipation and reinforcement efficiency of the composites as a function of fibre content in the temperature range of 0-140 oC. The composite with 30 wt.% of short carbon fibres has been observed to exhibit superior thermo-mechanical response with highest energy dissipation/damping ability accompanied with a constant storage modulus without any substantial decay till 60 oC. The erosion rates (Er) of these composites are evaluated at different impingement angles (30-90o), fibre loadings (20-50 wt.%), impact velocities (43-76 m/s), stand-off distances (55-85 mm) and erodent sizes (250-600 μm) following the erosion test schedule in an air jet type test rig. An optimal parameter combination is determined and subsequently validated for erosion rate minimization following Taguchi method and by conducting confirmation experiments. A correlation between the loss-modulus inverse and the erosion rate has been observed which conceptually establishes a possible mechanistic equivalence between erosion and dynamic mechanical loading modes. The morphologies of eroded surface are examined by the scanning electron microscopy to investigate the nature of wear-craters, material damage mode and other qualitative attributes responsible for promoting erosion.

  14. Thermo-mechanical analysis of rotating disks with non-uniform thickness and material properties

    Theoretical and numerical analyses of rotating disks with non-uniform thickness and material properties subjected to thermo-mechanical loadings have been carried out by variable material properties (VMP), Runge–Kutta's (RK) and finite element (FE) methods. The material is assumed to be elastic-linear hardening. A power form function is used to describe the temperature gradient with the higher temperature at outer surface. Von-Mises theory has been used as failure criterion. The effects of geometry, material and thermal loading parameters as well as boundary conditions on radial, hoop and equivalent stress distributions which have not been studied in much detail in previous works have been investigated. Good agreement between the results obtained from the three proposed methods is observed. It has also been observed a coarser mesh can be used in RK. Compared with previous works published by authors using variable iteration method, Adomian method, and Homotopy analysis method, VMP was found to be much easier for computer implementation and required less CPU time and computer memory and hardware. Highlights: ► FGM rotating disk subjected to thermo-mechanical loadings have been studied by three methods. ► Variable material properties, Runge–Kutta's (RK) and finite element (FE) methods are used. ► The effects of geometry, material, thermal loading and boundary conditions are discussed. ► Good agreement between the results obtained from the three proposed methods is observed. ► VMP is much easier for computer implementation and required less computation time and hardware.

  15. Thermo-mechanical tests on W7-X current lead flanges

    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

  16. A meshless approach to thermomechanics of DC casting of aluminium billets

    Mavrič, B.; Šarler, B.

    2016-03-01

    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.

  17. Universal Rateless Codes From Coupled LT Codes

    Aref, Vahid

    2011-01-01

    It was recently shown that spatial coupling of individual low-density parity-check codes improves the belief-propagation threshold of the coupled ensemble essentially to the maximum a posteriori threshold of the underlying ensemble. We study the performance of spatially coupled low-density generator-matrix ensembles when used for transmission over binary-input memoryless output-symmetric channels. We show by means of density evolution that the threshold saturation phenomenon also takes place in this setting. Our motivation for studying low-density generator-matrix codes is that they can easily be converted into rateless codes. Although there are already several classes of excellent rateless codes known to date, rateless codes constructed via spatial coupling might offer some additional advantages. In particular, by the very nature of the threshold phenomenon one expects that codes constructed on this principle can be made to be universal, i.e., a single construction can uniformly approach capacity over the cl...

  18. The materiality of Code

    Soon, Winnie

    2014-01-01

    , Twitter and Facebook). The focus is not to investigate the functionalities and efficiencies of the code, but to study and interpret the program level of code in order to trace the use of various technological methods such as third-party libraries and platforms’ interfaces. These are important to...... understand the socio-technical side of a changing network environment. Through the study of code, including but not limited to source code, technical specifications and other materials in relation to the artwork production, I would like to explore the materiality of code that goes beyond technical...

  19. Codes from difference sets

    Ding, Cunsheng

    2014-01-01

    This is the first monograph on codebooks and linear codes from difference sets and almost difference sets. It aims at providing a survey of constructions of difference sets and almost difference sets as well as an in-depth treatment of codebooks and linear codes from difference sets and almost difference sets. To be self-contained, this monograph covers necessary mathematical foundations and the basics of coding theory. It also contains tables of best BCH codes and best cyclic codes over GF(2) and GF(3) up to length 125 and 79, respectively. This repository of tables can be used to benchmark

  20. (Sigma-Delta) Codes

    Boulagouaz, M.; Leroy, A

    2013-01-01

    In this paper we introduce the notion of cyclic ($f(t),\\sigma,\\delta$)-codes for $f(t)\\in \\Ore$. These codes generalize the $\\theta$-codes as introduced by D. Boucher, F. Ulmer, W. Geiselmann \\cite{BGU}. We construct generic and control matrices for these codes. As a particular case the ($\\si,\\de$)-$W$-code associated to a Wedderburn polynomial are defined and we show that their control matrices are given by generalized Vandermonde matrices. All the Wedderburn polynomials of $\\mathbb F_q[t;\\t...