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).

scholarly journals A new boundary element algorithm for modeling and simulation of nonlinear thermal stresses in micropolar FGA composites with temperature-dependent properties

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohamed Abdelsabour Fahmy
Keyword(s):  
Modeling And Simulation ◽  
Boundary Element ◽  
Thermal Stresses ◽  
Computation Time ◽  
Functionally Graded ◽  
Temperature Dependent ◽  
Time Step ◽  
Kirchhoff Transformation ◽  
Nonlinear Temperature ◽  
Temperature Dependent Properties

AbstractThe main aim of this article is to develop a new boundary element method (BEM) algorithm to model and simulate the nonlinear thermal stresses problems in micropolar functionally graded anisotropic (FGA) composites with temperature-dependent properties. Some inside points are chosen to treat the nonlinear terms and domain integrals. An integral formulation which is based on the use of Kirchhoff transformation is firstly used to simplify the transient heat conduction governing equation. Then, the residual nonlinear terms are carried out within the current formulation. The domain integrals can be effectively treated by applying the Cartesian transformation method (CTM). In the proposed BEM technique, the nonlinear temperature is computed on the boundary and some inside domain integral. Then, nonlinear displacement can be calculated at each time step. With the calculated temperature and displacement distributions, we can obtain the values of nonlinear thermal stresses. The efficiency of our proposed methodology has been improved by using the communication-avoiding versions of the Arnoldi (CA-Arnoldi) preconditioner for solving the resulting linear systems arising from the BEM to reduce the iterations number and computation time. The numerical outcomes establish the influence of temperature-dependent properties on the nonlinear temperature distribution, and investigate the effect of the functionally graded parameter on the nonlinear displacements and thermal stresses, through the micropolar FGA composites with temperature-dependent properties. These numerical outcomes also confirm the validity, precision and effectiveness of the proposed modeling and simulation methodology.

Estimation of Effective Thermal and Mechanical Properties of Particulate Thermal Interface Materials (TIMs) by a Random Network Model

2017 ◽  
Author(s):  
Pavan Kumar Vaitheeswaran ◽  
Ganesh Subbarayan
Keyword(s):  
Mechanical Properties ◽  
Network Model ◽  
Thermal Stresses ◽  
Volume Fraction ◽  
Random Network ◽  
Thermal Interface Materials ◽  
Thermal And Mechanical Properties ◽  
Thermal Interface ◽  
Classical Models ◽  
Interface Materials

Particulate thermal interface materials (TIMs) are commonly used to transport heat from chip to heat sink. While high thermal conductance is achieved by large volume loadings of highly conducting particles in a compliant matrix, small volume loadings of stiff particles will ensure reduced thermal stresses in the brittle silicon device. Developing numerical models to estimate effective thermal and mechanical properties of TIM systems would help optimize TIM performance with respect to these conflicting requirements. Classical models, often based on single particle solutions or regular arrangement of particles, are insufficient as real-life TIM systems contain a distriubtion of particles at high volume fractions, where classical models are invalid. In our earlier work, a computationally efficient random network model was developed to estimate the effective thermal conductivity of TIM systems [1,2]. This model is extended in this paper to estimate the effective elastic modulus of TIMs. Realistic microstructures are simulated and analyzed using the proposed method. Factors affecting the modulus (volume fraction and particle size distribution) are also studied.

Impacts of Temperature on Mechanical Properties of FGMs

2014 ◽  
Vol 633-634 ◽  
pp. 391-395
Author(s):  
Wen Guang Liu ◽  
Cheng Yan
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Hypersonic Vehicle ◽  
Harsh Environment ◽  
Power Law Distribution ◽  
Temperature Dependent ◽  
Gradient Materials ◽  
Functionally Gradient ◽  
Property Model ◽  
Set Up

According to the Hypersonic Vehicle harsh environment, impacts of temperature on the mechanical properties for functionally gradient materials are studied. A power-law distribution of material is applied between the two pure materials; a material property model of FGMs is built. Several temperature conditions are set up and the results are obtained in the end through numerical analysis. It can be shown that the material properties of FGMs plate are temperature-dependent and vary along the thickness in terms of volume fractions of constituents.

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.

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.

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.

scholarly journals Effects of Material Properties on Angular Distortion in Wire Arc Additive Manufacturing: Experimental and Computational Analyses

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1399
Author(s):  
Sang-Cheol Park ◽  
Hee-Seon Bang ◽  
Woo-Jae Seong
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Heat Input ◽  
Coefficient Of Thermal Expansion ◽  
Angular Distortion ◽  
Substrate Thickness ◽  
Deformation Characteristics ◽  
Temperature Dependent ◽  
Temperature Dependent Properties ◽  
Wire Arc Additive Manufacturing

In wire arc additive manufacturing (AM), as in arc welding, arc heat thermally deforms substrates and articles. For industrial applications, deformation characteristics of various materials must be understood and appropriate materials and methods of reducing deformation must be devised. Therefore, angular distortions of different materials were investigated through bead-on-plate welding and finite element analysis. A model that simplifies temperature-dependent properties was developed to establish relationships between thermomechanical properties and angular distortion. A simplified model of temperature-dependent properties was used, and angular distortion characteristics were extensively investigated for different material properties and heat inputs. Coefficient of thermal expansion, density, and specific heat all notably affected angular distortion depending on heat input conditions. Results showed that during wire arc AM, flatness of both substrates and articles could vary depending on material properties, heat input, substrate thickness, and bead accumulation. Study findings can provide insight into deformation characteristics of new materials and how to mitigate thermal distortions.

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