scholarly journals Development of Nickel Alloy Reinforced with Fused SiO2 Chilled Composites and Evaluation of Thermal Properties (Thermal Conductivity & Coefficient of Thermal Expansion) and Temperature Distribution by Finite Element Analysis (FEA)

2017 ◽  
Vol 07 (05) ◽  
pp. 251-264 ◽  
Author(s):  
Joel Hemanth
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Temperature Distribution ◽  
Nickel Alloy ◽  
Coefficient Of Thermal Expansion ◽  
Element Analysis

Finite-Element Modeling and Analysis of Early-Age Cracking Risk of Cast-In-Place Concrete Culverts

2018 ◽  
Vol 2672 (27) ◽  
pp. 24-36 ◽  
Author(s):  
Yalin Liu ◽  
Anton K. Schindler ◽  
James S. Davidson
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Lightweight Concrete ◽  
Coefficient Of Thermal Expansion ◽  
Early Age ◽  
Thermal Coefficient ◽  
Element Analysis ◽  
Joint Spacing ◽  
Cracking Risk

Extensive cracking was found in several cast-in-place concrete culverts in Alabama. This condition can decrease the long-term durability of the culverts. Early-age stress development in concrete is influenced by temperature changes, modulus of elasticity, stress relaxation, shrinkage, thermal coefficient of expansion, and the degree of restraint. The objective of this study is to determine means to mitigate early-age cracking in culverts by evaluating the cracking risk. Finite-element analysis was used to model the early-age stress by accounting for the following factors: construction sequencing, support restraint, concrete constituents, temperature effects, and the time-dependent development of mechanical properties, creep/relaxation, and drying shrinkage. Experimental results from restraint to volume change tests with rigid cracking frames were used to verify the accuracy of the finite-element analysis. A parametric study was performed to quantify the effect of changing joint spacing, joint type, construction sequence, concrete coefficient of thermal expansion, placement season, and concrete type on the risk of early-age cracking. The finite-element model results revealed that the use of the following measures will reduce the risk of early-age cracking in cast-in-place concrete culverts: concrete with lower coefficient of thermal expansion, contraction joints, sand-lightweight concrete or all-lightweight concrete, and scheduling the casting of the culvert wall to minimize the difference in its placement time relative to its previously cast base. Alternatively, to minimize the contribution of thermal effects on risk of cracking, the construction schedule should be developed to avoid concrete placement during hot weather conditions.

PROCESS OPTIMIZATION AND SENSITIVITY INVESTIGATION IN LASER FORMING WITH FINITE ELEMENT ANALYSIS

2007 ◽  
Vol 04 (04) ◽  
pp. 653-670 ◽  
Author(s):  
H. C. JUNG ◽  
S. KRUMDIECK
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Process Optimization ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Laser Forming ◽  
Bend Angle ◽  
Forming Process ◽  
Element Analysis

Laser forming is a flexible sheet metal manufacturing technique capable of producing various shapes, without hard tools and external forces, by irradiation across the surface of the metal piece. A three-dimensional thermal-elasto-plastic (TEP) finite element model for a straight line laser forming process has been developed during the course of this study, which simulates bend angles and temperature distributions. Laser forming process optimization and material sensitivity are investigated. In order to seek the optimal process conditions to generate a desired bend angle in the multi-scan laser bending process, an optimization algorithm based on the approximation of objective function and state variables is integrated into the numerical model. An optimal set of process parameters such as laser power, scan speed, beam diameter and the number of scans are obtained with optimization procedure. In order to assess process sensitivity to material roperties, associations between bend angle and material properties are statistically determined using the Pearson product-moment correlation coefficient via Monte Carlo simulations, for which a large number of the finite element simulations are carried out. The material properties of interest include the coefficient of thermal expansion, thermal conductivity, specific heat, modulus of elasticity, and Poisson's ratio. Results show that the process optimization coupled with finite element analysis can be used to determine processing parameters, and that the material properties of primary importance are the coefficient of thermal expansion, thermal conductivity and specific heat.

Direct Study of the Thermal Conductivity in Aluminum Nanowires

2009 ◽  
Vol 1221 ◽  
Author(s):  
Nenad Stojanovic ◽  
D.H.S. Maithripala ◽  
Jordan M. Berg ◽  
Mark Holtz
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Electrical Resistivity ◽  
Thermal Properties ◽  
Electron Transport ◽  
Theoretical Prediction ◽  
Room Temperature ◽  
Total Thermal Conductivity ◽  
Element Analysis

AbstractThermal conductivity and electrical resistivity of 1 μm long aluminum nanowires, 75, 100, and 150nm in width and 100nm thick, were measured at room temperature. The method consists of microfabricated electrothermal test devices and a model-based data processing approach using finite-element analysis (FEA). The electrical and thermal properties of the nanowires differ significantly from bulk values while electrical resistivity agrees well with theoretical prediction. Electron transport equation models, which adequately describe the resistivity data, consistently underestimate the thermal conductivity. Incorporating a phonon contribution of ˜ 21 W/m·K to the total thermal conductivity is found to accurately describe the measured values.

Finite element analysis of WC–Al2O3 composites

2014 ◽  
Vol 03 (01) ◽  
pp. 1450002
Author(s):  
Satyanarayan Patel ◽  
Rahul Vaish
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Analytical Methods ◽  
Object Oriented ◽  
Stress And Strain ◽  
Thermal And Mechanical Properties ◽  
Element Analysis

Object oriented finite element analysis (OOF2) is used to estimate the thermal and mechanical properties of WC– Al 2 O 3 composites. In the present work, five compositions of 10%, 20%, 30%, 40% and 50% Al 2 O 3 (by volume) are studied. Young's modulus, thermal conductivity and thermal expansion coefficient are estimated using OOF2 and compared with other known analytical methods. Stress and strain contours are plotted to study the thermal and mechanical behavior of composites. It is found that the stresses are largely concentrated at the interfaces of the WC– Al 2 O 3 phases.

Effect of Refractory᾽s Thermal Expansion Coefficient on the Stress Field of the Top of Gasifier

2011 ◽  
Vol 418-420 ◽  
pp. 997-1001
Author(s):  
Wen Dong Xue ◽  
Xiao Xiao Huang ◽  
Jing Xie ◽  
Gang Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Temperature Field ◽  
Stress Field ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Coefficient Of Thermal Expansion ◽  
Element Analysis ◽  
Analysis Technique

The top of COREX-C3000 gasifier was simulated with a finite element analysis technique. It is studied of the influence of thermal expansion coefficient of the refractories on the temperature field and stress field and the function discipline with different parameters. The results of the simulation indicated that when the coefficient of thermal expansion of working lining and permanent lining are respectively 3.5×10-6/K and 4.5×10-6/K, the distortion and initial stress of the gasifier top are much less.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

Linear Thermomechanical Microactuators

1999 ◽  
Author(s):  
Rebecca Cragun ◽  
Larry L. Howell
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Expansion ◽  
Cross Sections ◽  
Variable Cross ◽  
Element Analysis ◽  
Thermal Actuators ◽  
Output Force ◽  
Analysis Models ◽  
High Output

Abstract Thermomechanical in-plane microactuators (TIMs) have been designed, modeled, fabricated, and tested. TIMs offer an alternative to arrays of smaller thermal actuators to obtain high output forces. The design is easily modified to obtain the desired output force or deflection for specific applications. The operational principle is based on the symmetrical thermal expansion of variable cross sections of the surface micromachined microdevice. Sixteen configurations of TIMs were fabricated of polysilicon. Finite element analysis models were used to predict the deflection and output force for the actuators. Experimental results were also recorded for all sixteen configurations, including deflections and output forces up to 20 micron and 35 dyne.

scholarly journals Investigation on Die Crack in a Stacked Die Package Using Finite Element Analysis

2021 ◽  
pp. 83-91
Author(s):  
Jefferson Talledo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Coefficient Of Thermal Expansion ◽  
Crack Problem ◽  
Element Analysis ◽  
Robust Solution ◽  
Die Attach ◽  
Die Stress ◽  
Cte Mismatch ◽  
Semiconductor Packages

Die crack is one of the problems in stacked die semiconductor packages. As silicon dies become thinner in such packages due to miniaturization requirement, the tendency to have die crack increases. This study presents the investigation done on a die crack issue in a stacked die package using finite element analysis (FEA). The die stress induced during the package assembly processes from die attach to package strip reflow was analyzed and compared with the actual die crack failure in terms of the location of maximum die stress at unit level as well as strip level. Stresses in the die due to coefficient of thermal expansion (CTE) mismatch of the package component materials and mechanical bending of the package in strip format were taken into consideration. Comparison of the die stress with actual die crack pointed to strip bending as the cause of the problem and not CTE mismatch. It was found that the die crack was not due to the thermal processes involved during package assembly. This study showed that analyzing die stress using FEA could help identify the root cause of a die crack problem during the stacked die package assembly and manufacturing as crack occurs at locations of maximum stress. The die crack mechanism can also be understood through FEA simulation and such understanding is very important in coming up with robust solution.

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