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.

Application of CFD to Solve Difficult Industry Thermal Stress Problems

2010 ◽  
Author(s):  
David J. Dewees
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Stress Analysis ◽  
Temperature Measurement ◽  
Temperature Gradients ◽  
Heat Transfer Analysis ◽  
Thermal Stress Analysis ◽  
Standard Heat ◽  
Computational Fluid Dynamics Cfd ◽  
Heat Transfer Correlations

Temperature variation is the source of load in pure thermal stress analysis; thus, meaningful prediction of temperatures in a structure is critical to analysis success. Temperature measurement and standard heat transfer correlations should be the basis of the majority of heat transfer analysis. However, there is a class of problems where temperature measurement is not possible or feasible and standard heat transfer correlations are not applicable. For cases such as these, computational fluid dynamics (CFD) provides a valuable tool to better assess the fluid/thermal behavior in complex configurations, and thus the resulting temperature gradients within a structure. Several practical examples that illustrate the value of CFD in thermal stress analysis are detailed in this paper.

Investigation Into Thermal Stress Characteristics of Pipe-in-Pipe Under High Temperature Condition

2018 ◽  
Author(s):  
Si-Hwa Jeong ◽  
Min-Gu Won ◽  
Nam-Su Huh ◽  
Yun-Jae Kim ◽  
Young-Jin Oh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
High Temperature ◽  
Temperature Distribution ◽  
Heat Transfer Analysis ◽  
Piping System ◽  
Curved Pipe ◽  
High Temperature Condition ◽  
Single Pipe ◽  
Radiation Conditions

In this paper, the thermal stress characteristics of the pipe-in-pipe (PIP) system under high temperature condition are analyzed. The PIP is a type of pipe applied in sodium-cooled faster reactor (SFR) and has a different geometry from a single pipe. In particular, under the high temperature condition of the SFR, the high thermal stress is generated due to the temperature gradient occurring between the inner pipe and outer pipe. To investigate the thermal stress characteristics, three cases are considered according to geometry of the support. The fully constrained support and intermediate support are considered for case 1 and 2, respectively. For case 3, both supports are applied to the actual curved pipe. The finite element (FE) analyses are performed in two steps for each case. Firstly, the heat transfer analysis is carried out considering the thermal conduction, convection and radiation conditions. From the heat transfer analysis, the temperature distribution results in the piping system are obtained. Secondly, the structural analysis is performed considering the temperature distribution results and boundary conditions. Finally, the effects of the geometric characteristics on the thermal stress in the PIP system are analyzed.

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