A Feasibility Investigation on Improving Structural Integrity of Thermoelectric Modules With Varying Geometry

2012 ◽  
Author(s):  
Ugur Erturun ◽  
Karla Mossi
Keyword(s):  
Power Generation ◽  
Material Properties ◽  
Thermal Stresses ◽  
Structural Integrity ◽  
Temperature Dependent ◽  
Thermoelectric Modules ◽  
Geometry Model ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Ansys Workbench

This study investigates the feasibility of improving the structural integrity of thermoelectric modules (TEMs) with varying geometry. For this purpose, six different TEM models with various thermoelectric leg geometries were designed and modeled in order to perform a thermal stress FEA using ANSYS Workbench. Temperature dependent material properties were used since some properties such as coefficients of thermal expansion change with temperature. Significant decrease in thermal stresses and leg deformations were observed with some models. Particularly, the cylindrical TE leg geometry model has approximately 54% lower Von Mises stresses (294MPa) and 13% lower TE leg deformations (3.9μm) than those of the typical TE leg geometry model (635MPa and 4.5μm). Power generation analyses of the models were performed to evaluate the effect of new TE leg geometries on the performance. TEM model with cylindrical TE leg geometry has the highest power generation (29.3mW) among all the models.

Mechanics of Composite Layered Rough Medium in Contact

2013 ◽  
Vol 703 ◽  
pp. 200-203
Author(s):  
Shao Biao Cai ◽  
Yong Li Zhao
Keyword(s):  
Material Properties ◽  
Three Dimensional ◽  
Shear Stresses ◽  
Normal Loading ◽  
Layered Coatings ◽  
Pressure Profiles ◽  
Tangential Traction ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Tangential Friction

This study presents a first attempt to develop a numerical three-dimensional multilayered (more than 2 composite layered coatings) elasticperfectly plastic rough solids model to investigate the contact behavior under combined normal loading and tangential traction. Contact analyses are performed to study the effects composite thin film layers. Local contact pressure profiles, von Mises stresses, and shear stresses as a function of material properties and applied normal and tangential friction loads are calculated.

A Methodology for Online Fatigue Monitoring With Consideration of Temperature-Dependent Material Properties Using Artificial Parameter Method

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Hengliang Zhang ◽  
Yangheng Xiong ◽  
Chu Nie ◽  
Danmei Xie ◽  
Kunfeng Sun
Keyword(s):  
Material Properties ◽  
Thermal Stresses ◽  
Function Technique ◽  
Parameter Method ◽  
Temperature Dependent ◽  
Linear Superposition ◽  
Thermal Transients ◽  
Fatigue Damage Accumulation ◽  
Fatigue Monitoring ◽  
Artificial Parameter

Following the basis of the ASME codes, the major nuclear components are designed to successfully avoid the fatigue failure. However, such design is generally very conservative and it is necessary to accurately assess the fatigue life of the components for the optimal life. The assessment of fatigue damage accumulation due to the thermal transients is currently performed via online fatigue monitoring systems. The algorithms for online calculation of thermal stress are one of the main components of these systems and are often based on the Green function technique (GFT), in which machine parameters such as fluid temperatures, pressures, and flow rates are converted into metal temperature transients and thermal stresses. However, since the GFT is based upon the linear superposition principle, it cannot be directly used when the temperature-dependent material properties are considered. This paper presents a methodology to consider the temperature- dependent material properties using artificial parameter method. Two cases are presented to compare the results calculated from the proposed models with those calculated by finite element method (FEM). It is found that the temperature-dependent material properties have significant influence on the maximum peak stresses which can be accurately captured by the models proposed in this work.

Effect of Geometrical Uncertainty on Cemented Hip Implant Structural Integrity

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Mamadou T. Bah ◽  
Martin Browne
Keyword(s):  
Structural Integrity ◽  
Simulation Method ◽  
Cement Mantle ◽  
Direct Monte Carlo Simulation ◽  
Modes Of Failure ◽  
Surface Method ◽  
Element Input ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Geometrical Uncertainty

A large number of parameters such as material properties, geometry, and structural strength are involved in the design and analysis of cemented hip implants. Uncertainties in these parameters have a potential to compromise the structural performance and lifetime of implants. Statistical analyses are well suited to investigating this type of problem as they can estimate the influence of these uncertainties on the incidence of failure. Recent investigations have focused on the effect of uncertainty in cement properties and loading condition on the integrity of the construct. The present study hypothesizes that geometrical uncertainties will play a role in cement mantle failure. Finite element input parameters were simulated as random variables and different modes of failure were investigated using a response surface method (RSM). The magnitude of random von Mises stresses varied up to 8 MPa, compared with a maximum nominal value of 2.38 MPa. Results obtained using RSM are shown to match well with a benchmark direct Monte Carlo simulation method. The resulting probability that the maximum cement stress will exceed the nominal stress is 62%. The load and the bone and prosthesis geometries were found to be the parameters most likely to influence the magnitude of the cement stresses and therefore to contribute most to the probability of failure.

Thermal Stresses in Materials with Temperature-Dependent Properties

1991 ◽  
Vol 44 (9) ◽  
pp. 383-397 ◽  
Author(s):  
Naotake Noda
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Metal Forming ◽  
Thermal Stresses ◽  
Main Theme ◽  
Thermal And Mechanical Properties ◽  
Temperature Dependent ◽  
Accurate Analysis ◽  
Thermoelastic Problems ◽  
Temperature Dependent Properties

The present review on thermal stresses in materials with temperature-dependent properties focuses on papers published after 1980. The thermal and mechanical properties in materials subjected to thermal loads due to high temperature, high gradient temperature, and cyclical changes of temperature are dependent on temperature. The main theme of the thermoelastic problems in materials and structures with temperature-dependent material properties is to establish analytical procedures to solve the governing differential equations. In the thermo-inelastic problems, however, we must perform more accurate analysis of the practical problems (weld, heat treatment, metal forming, etc) taking account of the temperature-dependent material properties by use of numerical procedures (finite element methods, mainly).

Modified Green’s Function Approach Using Temperature-Dependent Material Properties and Stress Properties for Thermal Fatigue Analysis

2012 ◽  
Vol 252 ◽  
pp. 32-35 ◽  
Author(s):  
Han Ok Ko ◽  
Myung Jo Jhung ◽  
Jae Boong Choi
Keyword(s):  
Green’S Function ◽  
Fatigue Damage ◽  
Green's Function ◽  
Material Properties ◽  
Power Plants ◽  
Thermal Stresses ◽  
Fatigue Analysis ◽  
Function Approach ◽  
Coolant Temperature ◽  
Temperature Dependent

Fatigue damage caused by alternating operational stresses in terms of temperature or pressure change is the one of important damage mechanisms in the nuclear power plants (NPPs). Although components important to safety were designed to withstand the fatigue damage, cumulative usage factor (CUF) at some locations can exceed the design limit beyond the design life. So, it is important to monitor the fatigue damage of major components during the long term operation. To evaluate fatigue damage, the Green’s function approach has been generally used. In this approach, thermal stresses can be directly calculated from the convolution integration on the coolant temperature history and Green’s function. And, Green’s function is defined as a stress variation at the arbitrary point when the coolant temperature is increased as a unit step. However, this approach cannot be applied to the fatigue analysis using temperature-dependent material properties because it is assumed that the system is linear. In this paper, the modified Green’s function approach considering temperature-dependent material properties is proposed by using neural network. To verify the modified Green’s function method, thermal stresses by the proposed method are compared with those by finite element analysis (FEA) at the transition wall of reactor pressure vessel and the analysis results between two methods are well agreed. Finally, it is anticipated that more precise fatigue evaluation is performed by using the proposed method.

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