Identification of Thermal Boundary Conditions using A Transient Temperature History

2004 ◽  
Vol 2004 (0) ◽  
pp. 247-248
Author(s):  
Kazunari MOMOSE ◽  
Kouhei ABE ◽  
Yoshikatsu SAWADA ◽  
Hideo KIMOTO
Keyword(s):  
Boundary Conditions ◽  
Temperature History ◽  
Transient Temperature ◽  
Thermal Boundary Conditions

Transient Thermo-Mechanical Stress Analysis of Hot Surface Probe Using Sequentially Coupled CFD-FEA Approach

2021 ◽  
Author(s):  
Sang-Guk Kang ◽  
Je Ir Ryu ◽  
Austen H. Motily ◽  
Prapassorn Numkiatsakul ◽  
Tonghun Lee ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Stress Analysis ◽  
Mechanical Stress ◽  
Failure Modes ◽  
Temperature History ◽  
Transient Temperature ◽  
Reacting Flow ◽  
Element Mesh ◽  
Surface Probe ◽  
Hot Surface

Abstract Energy addition using a hot surface probe is required for reliable ignition of aircraft compression ignition engines running on fuel variations and at altitude conditions. Thus, durability of the hot surface probe is crucial for application in these engines. Thermo-mechanical stress is one of the key parameters that determine durability, which requires an accurate prediction of the transient temperature field based on well-defined boundary conditions representing the dynamic and complex fluid flow inside engines. To meet this requirement, the present study focuses on transient thermo-mechanical stress analysis using a sequentially coupled CFD-FEA approach to understand transient thermo-mechanical responses of the hot surface probe. A 3D transient reacting flow simulation was conducted first using CONVERGE software, the results of which were exported to map thermal and pressure boundary conditions onto a structural finite element mesh. Transient thermo-mechanical stress analysis was performed sequentially using ABAQUS software utilizing the mapped boundary conditions. The results such as transient temperature history, resultant thermo-mechanical stress, displacement, potential failure modes, etc. were critically reviewed, which can provide helpful information for further design improvement.

An Inverse Method for the Determination of Thermal Stress-Intensity Factors Under Arbitrary Thermal-Shocks

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
J. Meeker ◽  
A. E. Segall ◽  
E. Gondar
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Opening ◽  
The Body ◽  
Temperature History ◽  
Transient Temperature ◽  
Intensity Factors ◽  
Thermal Boundary Conditions ◽  
Transient Temperature Distribution ◽  
Single Temperature

The analysis of stress-intensity factors is of immense importance when designing vessels, pipes, and end-caps as well as supporting structures and plates seen in high-temperature applications. Given this importance and the difficulty of measuring actual thermal boundary conditions, a generalized series based on a new and infinitely differentiable polynomial was employed to inversely determine the transient temperature distribution in a semi-infinite slab using only a single temperature history. These temperature distributions were in turn used to find the potential crack-opening stresses throughout the body. Using the found stresses and a weight-function approach, stress-intensity factors were then determined for both edge and semi-elliptical cracks under an arbitrary thermal-shock. When compared to other methods for various thermal scenarios, the method showed good agreement for both edge- and semi-elliptical surface cracks.

scholarly journals Inhomogeneous Temperature Distribution Affecting the Cyclic Aging of Li-Ion Cells. Part II: Analysis and Correlation

Batteries ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 12 ◽  
Author(s):  
Daniel Werner ◽  
Sabine Paarmann ◽  
Achim Wiebelt ◽  
Thomas Wetzel
Keyword(s):  
Boundary Conditions ◽  
Lithium Ion ◽  
Temperature Gradients ◽  
Transient Temperature ◽  
Aging Behavior ◽  
Thermal Boundary Conditions ◽  
Temperature Boundary ◽  
Inhomogeneous Temperature ◽  
Temperature Levels ◽  
Definition Of

Temperature has a significant influence on the behavior of batteries and their lifetime. There are several studies in literature that investigate the aging behavior under electrical load, but are limited to homogeneous, constant temperatures. This article presents an approach to quantifying cyclic aging of lithium-ion cells that takes into account complex thermal boundary conditions. It not only considers different temperature levels but also spatial and transient temperature gradients that can occur despite-or even due to-the use of thermal management systems. Capacity fade and impedance rise are used as measured quantities for degradation and correlated with the temperature boundary conditions during the aging process. The concept and definition of an equivalent aging temperature (EAT) is introduced to relate the degradation caused by spatial and temporal temperature inhomogeneities to similar degradation caused by a homogeneous steady temperature during electrical cycling. The results show an increased degradation at both lower and higher temperatures, which can be very well described by two superimposed exponential functions. These correlations also apply to cells that are cycled under the influence of spatial temperature gradients, both steady and transient. Only cells that are exposed to transient, but spatially homogeneous temperature conditions show a significantly different aging behavior. The concluding result is a correlation between temperature and aging rate, which is expressed as degradation per equivalent full cycle (EFC). This enables both temperature-dependent modeling of the aging behavior and its prediction.

Boundary Condition Design to Heat a Moving Object at Uniform Transient Temperature Using Inverse Formulation

2004 ◽  
Vol 126 (3) ◽  
pp. 619-626 ◽  
Author(s):  
Hakan Ertu¨rk ◽  
Ofodike A. Ezekoye ◽  
John R. Howell
Keyword(s):  
Boundary Condition ◽  
Temperature Distribution ◽  
Design Problem ◽  
Manufacturing Industry ◽  
Three Dimensional ◽  
Chemical Deposition ◽  
Iterative Solution ◽  
Conveyor Belt ◽  
Temperature History ◽  
Transient Temperature

The boundary condition design of a three-dimensional furnace that heats an object moving along a conveyor belt of an assembly line is considered. A furnace of this type can be used by the manufacturing industry for applications such as industrial baking, curing of paint, annealing or manufacturing through chemical deposition. The object that is to be heated moves along the furnace as it is heated following a specified temperature history. The spatial temperature distribution on the object is kept isothermal through the whole process. The temperature distribution of the heaters of the furnace should be changed as the object moves so that the specified temperature history can be satisfied. The design problem is transient where a series of inverse problems are solved. The process furnace considered is in the shape of a rectangular tunnel where the heaters are located on the top and the design object moves along the bottom. The inverse design approach is used for the solution, which is advantageous over a traditional trial-and-error solution where an iterative solution is required for every position as the object moves. The inverse formulation of the design problem is ill-posed and involves a set of Fredholm equations of the first kind. The use of advanced solvers that are able to regularize the resulting system is essential. These include the conjugate gradient method, the truncated singular value decomposition or Tikhonov regularization, rather than an ordinary solver, like Gauss-Seidel or Gauss elimination.

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