Thermal Elastoplastic Behavior of Dispersion Nuclear Fuel Elements

2011 ◽  
Vol 339 ◽  
pp. 353-357
Author(s):  
Xin Jiang ◽  
Xiao Hang Liu
Keyword(s):  
Plastic Strain ◽  
Volume Fraction ◽  
Large Strain ◽  
Equivalent Plastic Strain ◽  
Volume Element ◽  
Elastoplastic Behavior ◽  
Dispersion Fuel ◽  
The Matrix ◽  
Fuel Particles ◽  
Fuel Elements

A representative volume element is chosen to act as the research object to analyze the thermal elastoplastic behavior of the dispersion fuel elements. The large strain elastoplastic analysis is carried out for the mechanicalbehaviors using FEM. The results indicate that with the volume fraction of the fuel particles increasing, the Mises stress and the equivalent plastic strain in the matrix increases, and the first principal stress and the equivalent plastic strain in the cladding increases markedly.

The Temperature Field of Dispersion Nuclear Fuel Elements

2011 ◽  
Vol 374-377 ◽  
pp. 1955-1958
Author(s):  
Xin Jiang ◽  
Xiao Hang Liu
Keyword(s):  
Thermal Analysis ◽  
Temperature Field ◽  
Heat Generation ◽  
Volume Fraction ◽  
Volume Element ◽  
Heat Generation Rate ◽  
Dispersion Fuel ◽  
The Matrix ◽  
Fuel Particles ◽  
Fuel Elements

A representative volume element is chosen to act as the research object to analyze the temperature field of the dispersion fuel elements. The thermal analysis is carried out for the thermal behaviors using FEM. The results indicate that with the volume fraction and the heat generation rate of the fuel particles increasing, the temperature and the gradient of the temperature in the matrix and the cladding increases markedly.

scholarly journals The Electric Current Effect on Electrochemical Deconsolidation of Spherical Fuel Elements

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Xiaotong Chen ◽  
Zhenming Lu ◽  
Hongsheng Zhao ◽  
Bing Liu ◽  
Junguo Zhu ◽  
...  
Keyword(s):  
Electric Current ◽  
Photoelectron Spectroscopy ◽  
Energy Dispersive Spectrometer ◽  
Graphite Powder ◽  
X Ray ◽  
Graphite Matrix ◽  
Free Particles ◽  
The Matrix ◽  
Fuel Particles ◽  
Fuel Elements

For High-Temperature Gas-Cooled Reactor in China, fuel particles are bonded into spherical fuel elements by a carbonaceous matrix. For the study of fuel failure mechanism from individual fuel particles, an electrochemical deconsolidation apparatus was developed in this study to separate the particles from the carbonaceous matrix by disintegrating the matrix into fine graphite powder. The deconsolidated graphite powder and free particles were characterized by elemental analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and ceramography. The results showed that the morphology, size distribution, and element content of deconsolidated graphite matrix and free particles were notably affected by electric current intensity. The electrochemical deconsolidation mechanism of spherical fuel element was also discussed.

Micromechanics Study of Fatigue Damage Incubation Following an Initial Overstrain

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Yibin Xue ◽  
Amanda M. Wright ◽  
David L. McDowell ◽  
Mark F. Horstemeyer ◽  
Kiran Solanki ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Shear Strain ◽  
Equivalent Plastic Strain ◽  
Strain Range ◽  
Maximum Strain ◽  
Plastic Shear ◽  
Cyclic Plastic ◽  
Intermetallic Particles ◽  
Plastic Shear Strain ◽  
The Matrix

Understanding and quantifying the effects of overloads/overstrains on the cyclic damage accumulation at a microscale discontinuity is essential for the development of a multistage fatigue model under variable amplitude loading. Micromechanical simulations are conducted on a 7075-T651 Al alloy to quantify the cyclic microplasticity in the matrix adjacent to intact or cracked, life-limiting intermetallic particles. An initial overstrain followed by constant amplitude cyclic straining is simulated considering minimum to maximum strain ratios of 0 and −1. The nonlocal equivalent plastic strain at the cracked intermetallic particles reveals overload effects manifested in two forms: (1) the cyclic plastic shear strain range is greater in the cycles following an initial tensile overstrain than without the overstrain and (2) the initial overstrain causes the nonlocal cumulative equivalent plastic strain to double in subsequent tensile-going half cycles and triple in subsequent compressive-going half cycles, as compared with cases without an initial tensile overstrain. The cyclic plastic zone at the microdiscontinuity corresponds to that of the maximum strain during the initial overstrain and the nonlocal cyclic plastic shear strain range in the matrix near the intact or cracked inclusion is substantially increased for the same remote strain amplitude relative to the case without initial overstrain. These results differ completely from the effects of initial tensile overload on the response at a macroscopic notch root or at the tip of a long fatigue crack in which the driving forces for crack formation or growth, respectively, are reduced. The micromechanical simulation results support the incorporation of enhanced cyclic microplasticity and driving force to form fatigue cracks at cracked inclusions following an initial tensile overstrain in a fatigue incubation model.

The Thermal Expansion Coefficient of Dispersion Nuclear Fuel Elements

2014 ◽  
Vol 1039 ◽  
pp. 85-90
Author(s):  
Li Nie ◽  
Xiao Gang Wang ◽  
Xin Jiang ◽  
Chang Tao Pang
Keyword(s):  
Thermal Analysis ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Nuclear Fuel ◽  
Expansion Coefficient ◽  
Representative Volume Element ◽  
Theoretical Models ◽  
Volume Element ◽  
Dispersion Fuel ◽  
Fuel Elements

A representative volume element is chosen to act as the research object to analyze the thermal expansion coefficient of the dispersion fuel elements. The thermal analysis is carried out for the thermal behaviors using FEM. The results are compared with several theoretical models.

Numerical Investigation of the Overall Stiffness of Carbon Nanotube-Based Composite Materials

2011 ◽  
Vol 13 ◽  
pp. 47-59 ◽  
Author(s):  
Seyedmehdi Mavalizadeh ◽  
Moones Rahmandoust ◽  
Andreas Öchsner
Keyword(s):  
Carbon Nanotube ◽  
Young’S Modulus ◽  
Case Studies ◽  
Elastic Properties ◽  
Representative Volume Element ◽  
Volume Fraction ◽  
Young's Modulus ◽  
Volume Element ◽  
Matrix Volume ◽  
The Matrix

In this study, a finite element model of a representative volume element that contains a hollow and filled single-walled Carbon nanotube (SWCNT) in two case studies was generated. It was assumed that the nanocomposites have geometric periodicity with respect to local length scale and the elastic properties can be represented by those of the representative volume element (RVE). Elastic properties in agreement with existing literature values for the Carbon nanotube and the matrix were assigned. Then for the two case studies, the tensile test was simulated to find the effect of the geometry, i.e. the volume fraction of matrix and SWCNT's properties variation, on the effective Young's modulus of the structure. In another approach, by applying perpendicular loading to the tube direction, the effect of matrix volume fraction on the transverse Young's modulus was studied. The investigations showed that for both RVEs with filled SWCNT and hollow SWCNT, the effective Young's modulus of the structure decreases approximately linear as the matrix volume fraction increases. The value of Young's modulus of the RVE with a filled Carbon nanotube was obtained to be higher than the RVE with the hollow Carbon nanotube. In addition, by increasing the tube diameter, the effective Young's modulus of the structure increases and the transverse Young's modulus decreases approximately linear for filled tubes but this parameter remains rather constant in the case of the hollow tube by increasing the matrix volume fraction.

Cyclic Stress-Strain Response and Martensitic Transformation Behavior for Type 304 Stainless Steel

2014 ◽  
Vol 510 ◽  
pp. 114-117 ◽  
Author(s):  
Hiroshi Hamasaki ◽  
Eiichiro Ishimaru ◽  
Fusahito Yoshida
Keyword(s):  
Stainless Steel ◽  
Martensitic Transformation ◽  
Plastic Strain ◽  
Volume Fraction ◽  
Early Stage ◽  
Large Strain ◽  
Strain Curve ◽  
304 Stainless Steel ◽  
Stress Strain ◽  
Martensite Volume Fraction

Stress-strain responses of type SUS304 stainless steel at large strain under uniaxial tension and cyclic loading were investigated with special reference to plastic strain induced martensitic transformation. From the experiment it was found that the martensitic transformation plays an important role for the workhardening of the material at large strain, and a new finding from the cyclic experiment is that the stagnation of martensitic transformation appears at an early stage of reverse deformation. The evolutions of martensite volume fraction during monotonic and cyclic deformations were calculated by Stringfellow model, and it was found that the model is accurate enough for predicting the martensite volume fraction vs. plastic strain curve under monotonic loading case. On the other hand, it significantly overestimates the evolution of martensite volume fraction in a cyclic deformation.

Investigating the elastic behavior of carbon nanocone reinforced nanocomposites

2020 ◽  
Vol 234 (14) ◽  
pp. 2908-2922
Author(s):  
Bhavik A Ardeshana ◽  
Umang B Jani ◽  
Ajay M Patel ◽  
Anand Y Joshi
Keyword(s):  
Young’S Modulus ◽  
Representative Volume Element ◽  
Volume Fraction ◽  
Young's Modulus ◽  
Volume Element ◽  
Elastic Behavior ◽  
Representative Volume ◽  
Simulation Based ◽  
Load Carrying ◽  
The Matrix

This paper deals with the evaluation of the effective mechanical properties of carbon nanocone centered composites using a 3D nanoscale representative volume element based on continuum mechanics. For extracting the effective material constants, the authors have taken the basis of theories of elasticity. The results constituting the effective Young's modulus of the composite and Poisson's ratio for different parameters stated above have been presented and validated with rule of mixtures. It can be clearly visualized from the results that the load-carrying capacities of carbon nanocones in the representative volume elements are quite significant and the same has been demonstrated with subsequent cases. Simulation-based modeling can show a considerable part in the improvement of carbon nanocone-based composites by providing results that help in appreciative of the performance of composites. Moreover, for a volume fraction of the CNC as 2.33% in a cylindrical representative volume element and a 19.2° apex angle of the cone, the stiffness of the composite can increase as many as 4.9 times of the matrix. Similarly for hexagonal and square, the increase is in terms of 4.3 and 3.01 times respectively. Cylindrical representative volume element is the best as it provides the maximum reinforcement in terms of effective Young's modulus of the composite. Carbon nanocone-based composites provide results that help in understanding the elastic behavior of composites.

Formation of Persistent Slip Band in Fatigued Copper Single Crystals

1982 ◽  
Vol 40 ◽  
pp. 470-471
Author(s):  
N. Y. Jin
Keyword(s):  
Volume Fraction ◽  
Fatigue Cracks ◽  
Wall Structure ◽  
Matrix Structure ◽  
Dislocation Dipole ◽  
Slip Bands ◽  
Persistent Slip Bands ◽  
The Matrix ◽  
Hard Shell ◽  
Copper Single Crystals

Localised plastic deformation in Persistent Slip Bands(PSBs) is a characteristic feature of fatigue in many materials. The dislocation structure in the PSBs contains regularly spaced dislocation dipole walls occupying a volume fraction of around 10%. The remainder of the specimen, the inactive "matrix", contains dislocation veins at a volume fraction of 50% or more. Walls and veins are both separated by regions in which the dislocation density is lower by some orders of magnitude. Since the PSBs offer favorable sites for the initiation of fatigue cracks, the formation of the PSB wall structure is of great interest. Winter has proposed that PSBs form as the result of a transformation of the matrix structure to a regular wall structure, and that the instability occurs among the broad dipoles near the center of a vein rather than in the hard shell surounding the vein as argued by Kulmann-Wilsdorf.

Preparation of Electron Transparent Metal-Matrix Composites

1968 ◽  
Vol 26 ◽  
pp. 334-335 ◽  
Author(s):  
M. R. Pinnel ◽  
A. Lawley
Keyword(s):  
Stainless Steel ◽  
Load Transfer ◽  
Volume Fraction ◽  
Steel Wire ◽  
Initial Step ◽  
Interfacial Region ◽  
Matrix Composites ◽  
Specific Test ◽  
The Matrix ◽  
The One

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.

scholarly journals Continuous Cooling Transformation Behaviour and Bainite Transformation Kinetics of 23CrNi3Mo Carburised Steel

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 48
Author(s):  
Wenjun Song ◽  
Min Lei ◽  
Mingpan Wan ◽  
Chaowen Huang
Keyword(s):  
Phase Transformation ◽  
Volume Fraction ◽  
Austenite Formation ◽  
Steel Matrix ◽  
Transformation Kinetics ◽  
Bainite Transformation ◽  
Continuous Cooling ◽  
The Matrix ◽  
Dimensional Growth ◽  
Kinetics Of

In this study, the phase transformation behaviour of the carburised layer and the matrix of 23CrNi3Mo steel was comparatively investigated by constructing continuous cooling transformation (CCT) diagram, determining the volume fraction of retained austenite (RA) and plotting dilatometric curves. The results indicated that Austenite formation start temperature (Ac1) and Austenite formation finish temperature (Ac3) of the carburised layer decreased compared to the matrix, and the critical cooling rate (0.05 °C/s) of martensite transformation is significantly lower than that (0.8 °C/s) of the matrix. The main products of phase transformation in both the carburised layer and the matrix were martensite and bainite microstructures. Moreover, an increase in carbon content resulted in the formation of lamellar martensite in the carburised layer, whereas the martensite in the matrix was still lath. Furthermore, the volume fraction of RA in the carburised layer was higher than that in the matrix. Moreover, the bainite transformation kinetics of the 23CrNi3Mo steel matrix during the continuous cooling process indicated that the mian mechanism of bainite transformation of the 23CrNi3Mo steel matrix is two-dimensional growth and one-dimensional growth.

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