A Three-Dimensional Finite Difference Solution for the Thermal Stresses in Railcar Wheels

1969 ◽  
Vol 91 (3) ◽  
pp. 891-896 ◽  
Author(s):  
G. E. Novak ◽  
B. J. Eck
Keyword(s):  
Computer Program ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Transient Temperature ◽  
Shear Stresses ◽  
Radial Temperature ◽  
Closed Form Solutions ◽  
Brake Application ◽  
History Of ◽  
Thin Disks

A numerical solution is presented for both the transient temperature and three-dimensional stress distribution in a railcar wheel resulting from a simulated emergency brake application. A computer program has been written for generating thermoelastic solutions applicable to wheels of arbitrary contour with temperature variations in both axial and radial directions. The results include the effect of shear stresses caused by the axial-radial temperature gradients and the high degree of boundary irregularity associated with this type of problem. The program has been validated by computing thermoelastic solutions for thin disks and long cylinders; the computed values being in good agreement with the closed form solutions. Currently, the computer program is being extended to general stress solutions corresponding to the transient temperature distributions obtained by simulated drag brake applications. When this work is completed, it will be possible to synthesize the thermal history of a railcar wheel and investigate the effects of wheel geometry in relation to thermal fatigue.

Thermal Stress CAD Analysis of a Multi-Layer Composite of an Operating Transistor Package

1990 ◽  
Vol 112 (1) ◽  
pp. 77-80
Author(s):  
Agha J. Ghorieshi ◽  
Umid R. Nejib
Keyword(s):  
Thermal Stress ◽  
Thermal Stresses ◽  
Cooling System ◽  
Three Dimensional ◽  
Heat Transfer Analysis ◽  
Temperature Cycle ◽  
Shear Stresses ◽  
Layer Composite ◽  
Convection Cooling ◽  
Element Technique

Thermal stress management is a major factor in the design of an electronic package. Thermal mismatch among the assembled components induces thermal stresses within the device. Finite element technique is utilized for three dimensional thermal stress analysis of a transistor with a free convection cooling system. Heat transfer analysis is used to determine the temperature distribution throughout the package for a given operating temperature. The data are then used to determine package stresses. The results show the shear stress concentration is higher at the corner of the chip. These values were found to be lower compared to those using temperature cycle analysis. An alternative method of lowering shear stresses in the chip is suggested.

Analysis and Simulation of Thermal Transients and Resultant Stresses and Strains in TAB Packaging

1993 ◽  
Vol 115 (1) ◽  
pp. 34-38 ◽  
Author(s):  
M. A. Jog ◽  
I. M. Cohen ◽  
P. S. Ayyaswamy
Keyword(s):  
Thermal Stresses ◽  
Equivalent Stress ◽  
The Body ◽  
Temperature Fields ◽  
Transient Temperature ◽  
Shear Stresses ◽  
Transfer Coefficients ◽  
Thermal Transients ◽  
Power Cycling ◽  
Accelerated Thermal Cycling

During normal power cycling of the electronic equipment, the differing coefficients of thermal expansion result in differential elongations. Because each level of packaging is subject to mounting constraints, the differential strains result in bending and shear stresses. Repeated duty cycling can cause fatigue at joints, at interfaces between different materials, at interconnection locations, or cause delamination of composite materials. Accelerated Thermal Cycling (ATC) is done to simulate the fatigue failures that may arise because of this power cycling. The current practice is to determine ATC stresses by assuming that the temperatures of various layers are equal and constant. In this study, we have relaxed the isothermal assumption and we provide results for thermal stresses and strains in a first level package. This is accomplished by accurately determining the transient temperature fields in various layers of the package. Temperature variations for different heat transfer coefficients have also been calculated. The results indicate that realistic estimates of thermal stresses and strains are only possible with models that allow for temperature variation in the body of the package. High equivalent stress values are obtained at the chip-heat sink interface and in the bumps connecting the leads to the chip.

Three-Dimensional Thermal Analysis for Laser Assisted Milling of Silicon Nitride Ceramics Using FEA

2005 ◽  
Author(s):  
Xinwei Shen ◽  
W. J. Liu ◽  
Shuting Lei
Keyword(s):  
Silicon Nitride ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Transient Temperature ◽  
Operating Parameters ◽  
Beam Diameter ◽  
Transient Temperature Distribution ◽  
Failure Theory ◽  
Ceramic Machining ◽  
Laser Heat Source

Laser assisted machining (LAM) is one promising method for ceramic machining. In this paper, a three-dimensional heat transfer and thermal stress analysis is completed using commercial FEA software (ANSYS) to gain some insights on the thermal aspects for laser assisted milling. The transient temperature distribution was analyzed for a silicon nitride (Si3N4) ceramic workpiece undergoing a translating laser heat source which simulates the heating environment of the slot-milling operation with LAM. The effects of the operating parameters, such as laser power, laser beam diameter, laser preheat time and laser translating speed, were investigated. The thermal stresses induced from the steep temperature change and the effects of the operating parameters on thermal stresses were investigated. Additionally, the maximum-normal stress failure theory for brittle materials were employed to predict the possibility of cracking on ceramic workpiece due to thermal stresses.

A Study on the Interaction of Brain Impact With the Grounds of Different Material Types

2010 ◽  
Author(s):  
Parshuram Paka ◽  
Ghodrat Karami ◽  
Mariusz Ziejewski
Keyword(s):  
Shear Stress ◽  
Finite Elements ◽  
Material Properties ◽  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Time History ◽  
Human Head ◽  
Shear Stresses ◽  
History Of ◽  
The Brain

This paper proposes a parametric study of the response of brain, to human head impact with varied velocities as well as with the grounds of different material properties. The human head and its constituents are modeled using three-dimensional finite elements. The brain is made up of various elements that are modeled with a viscoelastic behavior. The ground is also assembled by finite elements. Five different velocities of impacts are considered based on realistic scenarios of human body falling due to gravity from five different heights. Three different materials for ground including wood, soil and rubber are considered. The simulation is run for a time history of 10ms after the incident. The intracranial coup pressure and shear stresses in the brain and various parts of the head are recorded. At the time of impact the peaks of the coup pressure and shear stress are observed to be proportional to the velocity of head and stiffness of the ground. Studies are conducted on the influence of the material of the impacting ground.

On the Thermal Stresses Generated in Cylindrical Shells With Application to Gas Turbine Combustors

1982 ◽  
Author(s):  
H. A. Nied
Keyword(s):  
Gas Turbine ◽  
Thermal Stresses ◽  
Longitudinal Direction ◽  
Temperature Fields ◽  
Shear Stresses ◽  
Gas Turbine Combustor ◽  
Closed Form Solutions ◽  
Bending Stresses ◽  
Cooling Hole ◽  
Axisymmetric Temperature

The thermal stresses generated in a cylindrical shell due to axisymmetric temperature fields, which vary in the longitudinal direction, are examined by using an influence function formulation. Closed form solutions for the longitudinal, hoop and shear stresses are derived for any axially varying temperature distribution expressible by a Fourier expansion. The thermal stresses generated in a typical cylindrical gas turbine combustor cooled by periodically spaced circumferential bands of cooling holes are investigated using the derived solutions. It is shown that a critical pitch in the cooling hole spacing can create high bending stresses at the cooling holes which could contribute to thermal fatigue failure.

Review of Buoyancy-Induced Flow in Rotating Cavities

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
J. Michael Owen ◽  
Christopher A. Long
Keyword(s):  
Thermal Stresses ◽  
Numerical Models ◽  
Three Dimensional ◽  
Solid Surfaces ◽  
Transient Temperature ◽  
Temperature Changes ◽  
Open Cavities ◽  
Induced Flow ◽  
Published Research ◽  
Buoyancy Induced Flow

Buoyancy-induced flow occurs in the cavity between two corotating compressor disks when the temperature of the disks and shroud is higher than that of the air in the cavity. Coriolis forces in the rotating fluid create cyclonic and anticyclonic circulations inside the cavity, and—as such flows are three-dimensional and unsteady—the heat transfer from the solid surfaces to the air is difficult either to compute or to measure. As these flows also tend to be unstable, one flow structure can change quasi-randomly to another. This makes it hard for designers of aeroengines to calculate the transient temperature changes, thermal stresses, and radial growth of the disks during engine accelerations and decelerations. This paper reviews published research on buoyancy-induced flow in closed rotating cavities and in open cavities with either an axial throughflow or a radial inflow of air. In particular, it includes references to experimental data that could be used to validate cfd codes and numerical models.

Analysis for Temperature Field and Stress of Concrete Volute Structure

2011 ◽  
Vol 90-93 ◽  
pp. 2418-2422
Author(s):  
Xiao Bing Sun ◽  
Xue Ping Peng
Keyword(s):  
Temperature Field ◽  
Optimization Design ◽  
Thermal Stresses ◽  
Heat Waves ◽  
Water Pressure ◽  
Three Dimensional ◽  
Transient Temperature ◽  
Transient Temperature Field ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Study on temperature field and thermal stresses of a large volume concrete volute structure is important to prevent the concrete structure cracking caused by excessively tensile strains that result from the cold or heat waves and the internal water pressure. By use of the three dimensional finite element method, the displacements and stresses of a concrete volute under the external loads are calculated. The transient temperature field and the thermal stress distribution of the concrete volute caused by the cold or heat waves are obtained, and the thermo-structural coupling stress field analyses for some cases are completed detailly. The calculating results are the basis for the optimization design of the concrete volute structure.

A photothermoelastic investigation of transient thermal stresses in wing ribs

1972 ◽  
Vol 7 (2) ◽  
pp. 117-124 ◽  
Author(s):  
E Matsumoto ◽  
S Sumi ◽  
T Sekiya
Keyword(s):  
Temperature Distribution ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Composite Model ◽  
New Technique ◽  
Transient Temperature ◽  
Transient Temperature Distribution ◽  
Transient Thermal

The photothermoelastic method of refrigeration has been used to study the problem of a long beam under transient temperature distribution and good correlation with the theoretical values has been obtained. The new technique for three-dimensional photothermoelasticity, which uses a composite model made of photoelastically sensitive and insensitive materials, is suggested for the analysis of idealized wing-rib structures.

Three-Dimensional Transient Interlaminar Thermal Stresses in Angle-Ply Composites

1989 ◽  
Vol 56 (3) ◽  
pp. 601-608 ◽  
Author(s):  
Yuan Ruo Wang ◽  
Tsu-Wei Chou
Keyword(s):  
Fiber Volume Fraction ◽  
Thermal Stresses ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Free Edge ◽  
Transient Temperature ◽  
Equilibrium Equations ◽  
Fiber Volume ◽  
Thermal Boundary Conditions ◽  
Transient Temperature Field

This paper studies the three-dimensional transient interlaminar thermal stresses in elastic, angle-ply laminated composites due to sudden changes in the thermal boundary conditions. The transient temperature field and transient interlaminar thermal stresses of the laminate are obtained by solving the heat conduction equation and by a zeroth-order perturbation analysis of the equilibrium equations, respectively. Numerical results for a four-layer angle-ply laminate have shown that the interlaminar normal stress near the free edge is significantly higher than that in the interior region and it increases rapidly with the fiber volume fraction.

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