Constitutive modeling and finite element procedure development for stress analysis of prismatic high temperature gas cooled reactor graphite core components

2013 ◽  
Vol 260 ◽  
pp. 145-154 ◽  
Author(s):  
Subhasish Mohanty ◽  
Saurindranath Majumdar ◽  
Makuteswara Srinivasan
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Stress Analysis ◽  
Constitutive Modeling ◽  
Reactor Graphite ◽  
Core Components ◽  
Finite Element Procedure ◽  
Procedure Development ◽  
High Temperature Gas

Failure and Reliability Analysis Influenced by Various Factors Using Accelerated Disturbed State Concept

2003 ◽  
Author(s):  
Russell D. Whitenack ◽  
Chandra S. Desai
Keyword(s):  
Finite Element ◽  
Reliability Analysis ◽  
Constitutive Modeling ◽  
Electronic Packaging ◽  
Analysis Tool ◽  
Disturbed State Concept ◽  
Powerful Approach ◽  
Finite Element Procedure ◽  
Cycles To Failure

The disturbed state concept (DSC) presented herein represents a unified and powerful approach for constitutive modeling of materials and interfaces in electronic packaging. Together with the computer finite element procedure it provides an analysis tool for calculation of stresses, strains, disturbance and cycles to failure. The accelerated procedure allows economical approximation of cycles to failure and distribution of disturbance at different cycles for design and reliability.

scholarly journals Modeling of Thermal and Mechanical Behavior of ZrB2-SiC Ceramics after High Temperature Oxidation

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jun Wei ◽  
Lokeswarappa R. Dharani ◽  
K. Chandrashekhara ◽  
Gregory E. Hilmas ◽  
William G. Fahrenholtz
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Thermal Stress ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Stress Analysis ◽  
Heat Transfer Analysis ◽  
Temperature Oxidation ◽  
Thermal Stress Analysis ◽  
Sic Ceramics

The effects of oxidation on heat transfer and mechanical behavior of ZrB2-SiC ceramics at high temperature are modeled using a micromechanics based finite element model. The model recognizes that when exposed to high temperature in air ZrB2-SiC oxidizes into ZrO2, SiO2, and SiC-depleted ZrB2 layer. A steady-state heat transfer analysis was conducted at first and that is followed by a thermal stress analysis. A “global-local modeling” technique is used combining finite element with infinite element for thermal stress analysis. A theoretical formulation is developed for calculating the thermal conductivity of liquid phase SiO2. All other temperature dependent thermal and mechanical properties were obtained from published literature. Thermal stress concentrations occur near the pore due to the geometric discontinuity and material properties mismatch between the ceramic matrix and the new products. The predicted results indicate the development of thermal stresses in the SiO2 and ZrO2 layers and high residual stresses in the SiC-depleted ZrB2 layer.

Scale Effects in the High Temperature Gas Pressure Forming of Electrodeposited Fine-Grained Copper Thin Sheet

2007 ◽  
Vol 551-552 ◽  
pp. 347-353
Author(s):  
K. Lei ◽  
Kai Feng Zhang ◽  
M.J. Tong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
High Temperature ◽  
Scale Effects ◽  
Gas Pressure ◽  
Small Scale ◽  
Fine Grained ◽  
Experimental Values ◽  
High Temperature Gas ◽  
Element Method

Scale effects in the high temperature gas pressure forming of electrodeposited fine-grained copper thin sheets were investigated by a series of tests at various forming temperatures and die apertures. The average as-deposited copper grain size was 5 μm. The geometrical parameters of the bugling die system and the thickness of copper sheet varied in proportion. Different radius hemisphere parts from 0.5mm to 5mm were obtained at a strain rate of 5.0×10−4 s−1, which was controlled by pressure forces curves determined in terms of a finite element method (FEM) based on constitutive equation proposed by Backoften in 1964. The experimental relative bulging height (RBH) values were measured, and compared with that predicted by the same finite element method (FEM). It was found that the experimental values of large scale parts approach to simulated values, whereas the experimental values of small scale parts were quite different from simulated values. In order to explain these phenomena, a grain-rotation-weakened mechanism was proposed.

Contact of an Inflated Toroidal Membrane with a Flat Surface as an Approach to the Tire Deflection Problem

1975 ◽  
Vol 3 (1) ◽  
pp. 43-61 ◽  
Author(s):  
J. DeEskinazi ◽  
W. Soedel ◽  
T. Y. Yang
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Nonlinear Effect ◽  
Reasonable Agreement ◽  
Large Deflection ◽  
Flat Surface ◽  
Nonlinear Load ◽  
Deflection Analysis ◽  
Finite Element Procedure ◽  
Good Agreement

Abstract A finite element procedure has been developed for the displacement and stress analysis of a homogeneous and isotropic inner tube mounted on a rim and in contact with a flat surface. The geometric nonlinear effect is accounted for by including the quadratic terms in the strain-displacement equations. The nonlinear load-displacement path is predicted by a linear incremental procedure. The procedure is first demonstrated by a large deflection analysis of a strip of a tire (a cable). The results are in good agreement with a known alternative solution. A homogeneous and isotropic inner tube is then pressurized and the displacements and stresses are found. The displacements are also found experimentally. Both results are in good agreement. Finally, the inner tube is mounted on a rim and pressed against a rigid flat surface. The resulting displacements and footprints are also measured experimentally. The computer results are shown to be in reasonable agreement with the experiment.

Degradation Characteristics of Combined Rotor for Turbine Considering Stress Relaxation of Rod

2013 ◽  
Vol 387 ◽  
pp. 168-173
Author(s):  
Yong Lei Su ◽  
Ai Lun Wang ◽  
Xue Peng Li
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Stress Relaxation ◽  
Stress Analysis ◽  
Dynamic Characteristic ◽  
Natural Frequency ◽  
Contact Stiffness ◽  
Frequency Drift ◽  
Microscopic Model ◽  
Calculating Method

Considering stress relaxation of rod under high temperature, pretightening force of rod changing with time was obtained. A finite element contact model with interface was analyzed and contact stiffness under different loads was concluded. Combining contact stiffness of the microscopic model with the stress analysis result of turbine interface, a calculating method for dynamic characteristic of combined rotor considering contact stiffness was presented, effect of rod relaxation on dynamic characteristic of combined rotor was obtained. The results showed that pretightening force of rod was decreasing due to stress relaxation, degradation of combined rotor that natural frequency drift caused by the stress relaxation of rod.

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