Effect of Temperature Dependent Mechanical Properties on Thermal Stress in Cooled Turbine Blades

1982 ◽  
Vol 104 (2) ◽  
pp. 349-353 ◽  
Author(s):  
J. M. Allen
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Effect Of Temperature ◽  
Cyclic Life ◽  
Temperature Dependent ◽  
Average Temperature ◽  
Order Of Magnitude ◽  
Computer Codes

Finite element analyses show that maximum thermal stresses in a typically cooled turbine blade are approximately 40 percent larger than they are if calculated assuming constant, average temperature material properties—even though the local-to-average properties vary only 2 to 3 percent. An error of this size in stress leads to an order of magnitude over prediction of cyclic life. This surprisingly large effect is explained by means of the solution for thermal stress in a flat plate with a thermal gradient through its thickness. In general, finite element computer codes allow for temperature dependency of properties, but some do not permit this dependency within an element. It is shown that this can be a serious limitation with higher-order elements.

Thermal Stress Simulation of the Surface Grinding

2011 ◽  
Vol 383-390 ◽  
pp. 2211-2215
Author(s):  
Chong Lue Hua ◽  
Gui Cheng Wang ◽  
Hong Jie Pei ◽  
Gang Liu
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Surface Grinding ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Temperature Dependent ◽  
Finite Element Procedure ◽  
Temperature Dependent Properties ◽  
Stress Simulation

Thermal stresses of grinding plays an important role on the fatigue and wear resistance of the component. A comprehensive analysis of thermal stress induced by surface grinding has been conducted with aid of the finite element method. To obtain a reliable figure of thermal stress induced by grinding, temperature-dependent properties of workpiece materials were taken into account. The developed finite element procedure has also been applied to calculate the surface and sub-surface thermal stress induced by moving source of triangular heat when convection and radiation is occurred over the whole work. Based on an analysis of the effects of wheel velocity on the thermal stress distributions in an elastic-plastic solid, some important conclusions were given.

Three Turnaround Heat Treating Studies

2003 ◽  
Author(s):  
Jaan Taagepera ◽  
Marty Clift ◽  
D. Mike DeHart ◽  
Keneth Marden
Keyword(s):  
Heat Treatment ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Heat Treating ◽  
Element Analysis ◽  
Stress Profiles ◽  
Insight Into

Three vessel modifications requiring heat treatment were analyzed prior to and during a planned turnaround at a refinery. One was a thick nozzle that required weld build up. This nozzle had been in hydrogen service and required bake-out to reduce the potential for cracking during the weld build up. Finite element analysis was used to study the thermal stresses involved in the bake-out. Another heat treatment studied was a PWHT of a nozzle replacement. The heat treatment band and temperature were varied with location in order to minimize cost and reduction in remaining strength of the vessel. Again, FEA was used to provide insight into the thermal stress profiles during heat treatment. The fmal heat treatment study was for inserting a new nozzle in a 1-1/4Cr-1/2Mo reactor. While this material would ordinarily require PWHT, the alteration was proposed to be installed without PWHT. Though accepted by the Jurisdiction, this nozzle installation was ultimately cancelled.

Transient Thermal Stress Analysis of the Typical Structures in Turbine Rotor Based on Thermomechanical Analysis

2014 ◽  
Author(s):  
Ning Xu ◽  
Zhansheng Liu ◽  
He Peng
Keyword(s):  
Finite Element ◽  
Heat Conduction ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Transition Process ◽  
Transient Heat Conduction ◽  
Work Conditions ◽  
Turbine Rotor ◽  
Design Stage ◽  
Turbine Rotors

Thermal stress is one of the most important monitoring parameters in turbine rotors during the transition of work conditions. It has significant influence on the safety and life of turbine rotors. In order to obtain the thermal stress in turbine rotors during the transition process conveniently, the transient heat conduction process in typical structures of turbine rotors is analyzed based on heat conduction equation and finite element simulation. According to thermomechanical principle, thermal stress distributions in the typical structures of turbine rotor are investigated. The solutions of thermal stress in a solid cylinder are derived. A corner formed by shaft and disc is modeled and analyzed by finite element method, and the influences of structure parameters on thermal stresses are studied. The results on thermal stresses in cylinder and corner structures could provide a continent method to estimate thermal stress of turbine rotor on early design stage.

The Effects of Severe Thermal and Pressure Transients on the Survival of Internally Coated Tubes

2010 ◽  
Author(s):  
J. T. Harris ◽  
A. E. Segall ◽  
R. Carter
Keyword(s):  
Finite Element ◽  
Thermal Stresses ◽  
Elastic Analysis ◽  
Uniform Heating ◽  
Temperature Dependent ◽  
Pressure Function ◽  
Stress States ◽  
Transient Thermal ◽  
Hoop Stresses ◽  
Over Time

The effects of severe thermal and pressure transient pulses on the interior of coated tubes have been analyzed using finite-element methods. For the modeling, an axisymmetric mesh was developed and used to assess the transient, thermal- and stress-states and the propensity for fracture related damage. For all calculations, temperature dependent thermophysical and elastic properties were used during the analysis. The model also utilized uniform heating and pressure across the ID surface imposed via convective coefficients and a piece-wise linear pressure function over time. Results for the strictly elastic analysis indicated that both had a significant influence on the maximum circumferential (hoop) stresses and temperatures and that the compressive thermal-stresses help to offset any tensile components generated by the internal pressure on the ID. Preliminary calculations also investigated the influence of these factors when a crack was introduced at the interface of the coating and substrate.

An Analysis of Thermo-Mechanical Behavior in a Multilayer Composite Pipe Under Temperature Variation

2010 ◽  
Author(s):  
Wei Yang ◽  
Jyhwen Wang
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Analytical Solution ◽  
Mechanical Behavior ◽  
Temperature Change ◽  
Thermal Stresses ◽  
Element Model ◽  
Functionally Graded ◽  
Element Analysis ◽  
Graded Materials

A generalized analytical solution of mechanical and thermal induced stresses in a multi-layer composite cylinder is presented. Based on the compatibility condition at the interfaces, an explicit solution of mechanical stress due to inner and outer surface pressures and thermal stress due to temperature change is derived. A finite element model is also developed to provide the comparison with the analytical solution. It was found that the analytical solutions are in good agreement with finite element analysis result. The analytical solution shows the non-linear dependency of thermal stress on the diameters, thicknesses and the material properties of the layers. It is also shown that the radial and circumferential thermal stresses depend linearly on the coefficients of thermal expansion of the materials and the temperature change. As demonstrated, this solution can also be applied to analyze the thermo-mechanical behavior of pipes coated with functionally graded materials.

Optimization of Wire Loop Height for a Cavity Down Plastic Pin Grid Array Package

1998 ◽  
Vol 120 (2) ◽  
pp. 194-200 ◽  
Author(s):  
I. Chaudhry ◽  
F. Barez
Keyword(s):  
Finite Element ◽  
Simulation Study ◽  
Thermal Stresses ◽  
Element Model ◽  
Temperature Cycling ◽  
Effect Of Temperature ◽  
Temperature Cycle ◽  
Wire Loop ◽  
Simulation Results ◽  
Test Points

A study has been conducted to resolve wire neck break problem in a cavity-down plastic pin grid array (PPGA) packages with a specific range of parameters when subjected to temperature cycle (−55°C/+125°C). In most cases, a weak or broken neck of the wire was observed after 300 cycles of temperature cycling. The objective of this study is to determine an optimum wire loop height so that the package can pass a 1000 temperature cycles. Results of a simulation study, performed by other researchers, using a finite element model (FEM) were utilized. Their work considered the effect of temperature cycling on PPGA packages identical to those in this report. Several possible factors that can contribute to this failure mechanism were analyzed, and stresses in the wires were evaluated. The simulation results were verified by running an experiment on actual parts. The parts were subjected to temperature cycling, and data was gathered at different test points. The experimental results obtained did concur with simulation results which suggested that the area just above the ball experienced a significant level of thermal stresses, and such stresses could be reduced by determining an optimum loop height.

scholarly journals Thermo-Mechanical Modeling of Distortions Promoted during Cooling of Ti-6Al-4V Part Produced by Superplastic Forming

2016 ◽  
Vol 838-839 ◽  
pp. 196-201
Author(s):  
Maxime Rollin ◽  
Vincent Velay ◽  
Luc Penazzi ◽  
Thomas Pottier ◽  
Thierry Sentenac ◽  
...  
Keyword(s):  
Finite Element ◽  
Thermal Stresses ◽  
Superplastic Forming ◽  
Model Material ◽  
Material Behavior ◽  
Mechanical Modeling ◽  
Temperature Dependent ◽  
Finite Element Software ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

In AIRBUS, most of the complex shaped titanium fairing parts of pylon and air inlets are produced by superplastic forming (SPF). These parts are cooled down after forming to ease their extraction and increase the production rate, but AIRBUS wastes a lot of time to go back over the geometric defects generated by the cooling step. This paper investigates the simulations of the SPF, cooling and clipping operations of a part on Abaqus® Finite element software. The different steps of the global process impact the final distortions. SPF impacts the thickness and the microstructure/behavior of material, cooling impacts also the microstructure/behavior of material and promotes distortions through thermal stresses and finally, clipping relaxes the residual stresses of the cut part. An elastic-viscoplastic power law is used to model material behavior during SPF and a temperature dependent elastic perfectly plastic model for the cooling and clipping operations.

scholarly journals STEADY-STATE THERMAL STRESS ANALYSIS OF GEARBOX CASING BY FINITE ELEMENT METHOD

2013 ◽  
pp. 118-122
Author(s):  
P. D. PATEL ◽  
D. S. SHAH
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Thermal Stress ◽  
Stress Analysis ◽  
Thermal Stresses ◽  
Dimensional Structure ◽  
Thermal Stress Analysis ◽  
Problem Solve ◽  
Von Mises ◽  
Element Method

This paper contains the gearbox casing analysis by finite element method (FEM). In previous study the thermal stresses have been affected on the performance of gearbox casing during the running conditions. So, this problem solve by thermal stress analysis method. Thermal stress analysis is the process of analyzing the effect of thermal and mechanical loads, and heat transfer of gearbox casing. In this paper, thermal stresses have been analyzed on gearbox casing, and thus temperature field has been coupled to the 3-Dimensional structure model using Fem. Paper also describes convection effect between the inner-surface of casing and the circulating oil which has been found small and thus neglected. Study of equivalent von-mises stresses in inner and outer gearbox casing with the coupled method has been done using ANSYS software. Result shows thermal stress analysis and deformation value under the action of force and heat. Result finds the thermal stress of the gearbox casing is 68.866 Mpa and 0.15434 mm for the deformation of the gearbox casing.

Finite Element Analysis of Thermal Stress in Multi-Arc Ion Plated ZrTiN Hard Coatings

2010 ◽  
Vol 139-141 ◽  
pp. 369-373 ◽  
Author(s):  
Pei Yan ◽  
Jian Xin Deng ◽  
Hai Bing Cui ◽  
Xing Ai ◽  
Jun Zhao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shear Stress ◽  
Thermal Stress ◽  
Coating Thickness ◽  
Deposition Temperature ◽  
Thermal Stresses ◽  
Hard Coatings ◽  
Element Analysis ◽  
Stress Components

The thermal stresses generated in ZrTiN coating deposited on HSS and tungsten carbide substrates are investigated by finite element analysis and calculated by mathematics model. FEM analysis provides detailed information about all stress components. The influence of deposition temperature, substrate materials, coating thickness and interlayers on the generation is analyzed. The thermal stress of coatings has a linear relationship with deposition temperature, and an inverse relationship with the coating thickness. The results of simulated thermal stress are in accordance with the analytical method. The highest shear stress found at the interface between the coating and substrate indicates that the interface is the critical location which is learned from the failure point of view. Results also show that the insertion of TiZr interlayer between the coating and substrate can reduce the stress components especially the shear stress. The interlayer thickness has a great effect on stress reduction.

Thermal Stress Analysis of SMT PQFP Packages and Interconnections

1989 ◽  
Vol 111 (1) ◽  
pp. 2-8 ◽  
Author(s):  
J. H. Lau
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Thermal Stress ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Mechanical Behavior ◽  
Thermal Stresses ◽  
Stress And Strain ◽  
Plastic Analysis ◽  
Chip Carrier

An elasto-plastic analysis of the thermal stresses and strains in a surface mounted plastic-quad-flat-pack (PQFP) assembly by using a 3-D finite element method is presented in this paper. Detailed stress and strain distributions and whole-field displacements of the assembly are also provided for a better understanding of its mechanical behavior during thermal cycling. It was found that the stresses and strains in the PQFP solder joint are smaller than those in the plastic-leaded-chip-carrier (PLCC) solder joint. The results presented herein should be useful in the design for reliability of this class of surface mount assemblies.

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