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2009-2010

FINAL YEAR PROJECT

DEPARTMENT OF MECHANICAL ENGINEERING

A.V.C COLLEGE OF ENGINEERING

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16TH APRIL 2010

PROJECT PRESENTATION

FINAL YEAR PROJECT

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PROJECT GUIDE : Mr.A.BALAJI, M.E., LECTURER IN MECHANICAL DEPARTMENT A.V.C COLLEGE OF ENGINEERING .

PROJECT STUDENTS

P.ANANDHAKUMAR (80106114002) G.ARULPRAKASAM (80106114003) G.PUGAZHENDHI (80106114025) M.DHINESH (80106114304)

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CONTENT INTRODUCTION PROJECT TITLE INTRODUCTION PROBLEMS OBJECTIVES EXPERIMENTAL METHOD TECHNICAL VIEWS METHODOLOGY COMPARISON OF RESULTS APPLICATIONS LITERATURE VIEW PROJECT STATUS

CONTENT

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ANALYSIS OF THERMAL CONDUCTIVITY AND THERMAL

STRESS ON

ALUMINIUM SILICONCARBIDE COMPOSITES

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INTRODUCTION

Heat transfer plays a important role in the performance of atomic reactors, rockets and jet engines and development work in progress.

The post-war era has consequently seen a substantial increase in the interest shown in the thermal properties of materials particularly in determinations of thermal conductivity..

In this work the thermal stress of Aluminium silicon carbide composites was analyzed .Effort was taken to prove the thermal conductivity of adding SiC with Aluminium.

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•The thermal conductivity of materials is defined as the amount of energy conducted through a body of unit area and unit thickness in unit time or heat flow per unit time across unit area when temperature gradient is unity.

• K = (Q/A) × (dx/dt)Where• K – Thermal Conductivity (W/mK)• Q – Heat transfer (W)• dx/dt – Temperature gradient

THERMAL CONDUCTIVITY

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•Thermal conductivity of material is due to flow of free electrons and lattice vibrational waves.

•Thermal conductivity in case of pure metal is the highest e.g. (Copper 385W/mK, silver 410w/mK﴿ it decreases with increase impurity.

•Thermal conductivity of a metal varies considerably when it is heat treated or mechanically processed.

•Thermal conductivity of most metal decreases with the increase in temperature.

REGARDING THERMAL CONDUCTIVITY

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THERMAL STRESS Stress introduced by uniform or non

uniform temperature change in a structure or material which is constrained against expansion or contraction.

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• A composite material is a combination of two or more materials having compositional variation and properties distinctively different from those of individual materials of the composite.

COMPOSITE MATERIAL

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PROBLEMS To determine the thermal conductivity of a composite

material is experimentally difficult.

For a composite material it is difficult to analyze the thermal stress in experimental method.

We need experimental results which were already proved.

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OBJECTIVES To analyze the thermal stress for a

composite material-Aluminum silicon carbide

To find a methodology to prove the thermal conductivity of a composite material.

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TRANSFER THE READINGS TO ANALYSIS METHOD

REFER THE READINGS FROM EXPERIMENTAL METHOD

THERMAL STRESS ANALYSIS TRANSIENT STATE ANALYSIS

COUPLED STRUCTURAL ANALYSIS GRAPHICAL METHOD

USING ANSYS & HYPERMESH

PROJECT VIEW

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EXPERIMENTAL METHOD

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REFERENCE PROJECT TITLE “DETERMINATION OF

THERMAL CONDUCTIVITY OF COMPOSITE MATERIALS”

MECHANICAL DEPARTMENT BATCH 2005-2009

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EXPERIMENTAL SETUP

WORKING PROCEDURE This method is a comparative one the unknown thermal

conductivity of the material was measured with the reference of materials whose thermal conductivities are known. Such reference materials were Aluminium, Castiron, and Stainless steel.

The initial cooling rate of various materials was found out. From the initial cooling rate, material can be identified as higher thermal conductivity and lower thermal conductivity whose thermal conductivities were already known.

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PROCEDURE Now the graph was drawn between thermal conductivity

Vs cooling rate. The thermal comparator embodying cones were placed

in a Muffle furnace Controlled at any temperature and left to attain equilibrium.

This was indicated by the reading of the differentially connected thermocouples being zero or within a few µv of these values.

Meanwhile the samples to be tested were positioned on an insulating blanket and allowed to come into equilibrium with room.

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PROCEDURE . The initial 70°C and equivalent microvolt readings of

differentially connected thermocouples were noted and subsequent readings were taken every 15 seconds after contact had been established.

The test was made on materials of higher thermal conductivity to lower thermal conductivity such as Aluminium, Castiron, Stainless steel And also Aluminium Silicon carbide with various proportion of SiC (5%, 10%, 15%).

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Material: AlSiC (SiC 5%)

S.No Time(sec)

Temperature (°C) Avg.Temp(°C)

VoltmeterReading

(µv)

TrialI

TrialII

TrialIII

1. 15 68 68 67 67.67 2752

2. 30 66 66 66 66 2679

3. 45 64 65 65 64.67 2626

4. 60 63 63 64 63.67 2585

5. 75 62 61 63 62 2517

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COOLING RATE Vs THERMAL CONDUCTIVITY AlSiC (SiC 5%)

COOLING RATE [v ]

thermal conductivity 151.67 W/mK

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• Aluminium silicon carbide is one of the composite materials whose thermal stress is to be analyzed in this project.• Basically metal matrix composites can be manufactured in three methods such as • Liquid phase processes• Solid phase processes• Liquid/Solid phase processes

SPECIMEN

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AlSiC COMPOSITE MATERIALS

Element%

Si 6.5 - 7.5

Fe 0.2

Cu 0.2

Mn 0.1

Mg 0.2 - 0.45

Zn 0.1

Ti 0.2

Al Remaining

SiC 25

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ANALYSIS METHOD

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TECHNICAL VIEWS HYPER MESH

For modelling and meshing the material

ANSYS

Steady state thermal analysis

Transient thermal analysis

Coupled structural analysis

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THERMAL ANALYSIS TYPES

STEADY STATE THERMAL ANALYSIS

TRANSIENT THERMAL ANALYSIS

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METHODOLOGY To create the shell of the specimen in

HYPER MESH. Conversion of model from hyper mesh to

ansys. Conduct steady state thermal analysis Apply the method of coupled structural

analysis. Then conduct Transient state analysis.

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HYPER MESH- PROCEDURE

Create a profile. Choose element – SHELL 57. Apply the values. Mesh the element. Export the values from hyper mesh to

ansys.

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•SHELL57 is a three-dimensional element having in-plane thermal conduction capability. •The element has four nodes with a single degree of freedom, temperature, at each node. •The conducting shell element is applicable to a three-dimensional, steady-state or transient thermal analysis

ELEMENT FOR THERMAL ANALYSIS

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SHELL57

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•SOLID185 is used for the three-dimensional modeling of solid structures.

• The element is defined by eight nodes having three degrees of freedom at each node: translations in the nodal x, y, and z directions.

ELEMENT FOR STRUCTURAL ANALYSIS

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SOLID185

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, "A sequentially coupled physics analysis is the combination of analyses from different engineering disciplines which interact to solve a global engineering problem. For convenience, ...the solutions and procedures associated with a particular engineering discipline [will be referred to as] a physics analysis. When the input of one physics analysis depends on the results from another analysis, the analyses are coupled."

COUPLED STRUCTURAL ANALYSIS

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Thermal Environment - Create Geometry and Define Thermal Properties1.Give a TitleUtility Menu > File > Change Title .../title, Thermal Stress Example2.Open preprocessor menuANSYS Main Menu > Preprocessor/PREP73.Define KeypointsPreprocessor > Modeling > Create > Keypoints > In Active CS...K,#,x,y,z

COUPLED STRUCTURAL ANALYSIS-PROCEDURE

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4.Create LinesPreprocessor > Modeling > Create > Lines > Lines > In Active cs

5.Define the Type of ElementPreprocessor > Element Type > Add/Edit/Delete...

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Define Real ConstantsPreprocessor > Real Constants... > Add...In the 'Real Constants for LINK33' window, enter the following geometric properties:

Define Element Material PropertiesPreprocessor > Material Props > Material Models > Thermal > Conductivity > Isotropic

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MODELLING IN HYPER MESH

SPECIFICATION OF SHELL L=150mm;B=50mm;T=10mm

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PROPERTY VALUES Young’s modulus 1.15*e5 N/mm2

Poisson’s ratio 0.3 Density 2.88*e-9 t/mm2

Thermal expansion 0.000015mm/0 C

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APPLYING BOUNDARY CONDITIONS

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Define Mesh SizePreprocessor > Meshing > Size Cntrls > ManualSize > Lines > All Lines...Mesh the framePreprocessor > Meshing > Mesh > Lines > click 'Pick All' Write EnvironmentThe thermal environment (the geometry and thermal properties) is now fully described and can be written to memory to be used at a later time

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Preprocessor > Physics > Environment > WriteIn the window that appears, enter the TITLE Thermal and click OK.

Clear EnvironmentPreprocessor > Physics > Environment > Clear > OK

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Structural Environment - Define Physical PropertiesSince the geometry of the problem has already been defined in the previous steps, all that is required is to detail the structural variables.

Switch Element TypePreprocessor > Element Type > Switch Elem TypeChoose Thermal to Struc from the srcoll down list.

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Define Element Material PropertiesPreprocessor > Material Props > Material Models > Structural > Linear > Elastic > IsotropicThe properties are from mat website density-2.88*10^-9 t/mm^2 E=115 Gpa

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1.Write EnvironmentThe structural environment is now fully described. Preprocessor > Physics > Environment > WriteIn the window that appears, enter the TITLE Struct

Solution Phase: Assigning Loads and SolvingDefine Analysis TypeSolution > Analysis Type > New Analysis > StaticANTYPE,0Read in the Thermal EnvironmentSolution > Physics > Environment > ReadChoose thermal and click OK.

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•Apply Constraints•Solution > Define Loads > Apply > Thermal > Temperature > On Keypoints•Solve the System•Solution > Solve > Current LSSOLVE•Close the Solution Menu•Main Menu > Finish

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Read in the Structural EnvironmentSolution > Physics > Environment > ReadChoose struct and click OK.Apply ConstraintsSolution > Define Loads > Apply > Structural > Displacement > On KeypointsInclude Thermal EffectsSolution > Define Loads > Apply > Structural > Temperature > From Therm Analy

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Define Reference TemperaturePreprocessor > Loads > Define Loads > Settings > Reference Temp

1.Solve the SystemSolution > Solve > Current LSSOLVE

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COUPLED STRUCTURAL ANALYSIS -NODAL SOLUTION

STRESS

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MAXIMUM TEMPERATURE DISTRIBUTION

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TRANSIENT STATE ANALYSIS

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COMPARISON OF RESULTS

S.NO TIME IN S EXPERIMENTAL METHOD

TEMPERATRE(°C)

ANALYSIS METHOD

TEMPERATURE(°C)

1 15 67.67 68.01

2 30 66 66.8

3 45 64.67 64.8

4 60 63.67 64.01

THE THERMAL CONDUCTIVITY AT 151.67W/mK.

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It was found that the temperature readings from experimental method and the temperature readings from analysis method are same at thermal conductivity 151.67 W/mK. Thus the thermal conductivity was proved that 151.67W/mK for aluminium siliconcarbide composites

A technique has been proposed using analysis method to prove the thermal conductivity of a composite material whose thermal conductivity is unknown.

CONCLUSIONS

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CONCLUSIONS

The thermal stress of AlSiC was analyzed an the maximum stress value obtained was 0.02539 N/mm2.

The thermal conductivity and thermal stress can be analyzed at unsteady state condition also.

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APPLICATIONS It can be used to evaluate performance of

atomic reactors, jet engines, rockets. It can be applicable to check the thermal

conductivity of a composite material. It is used to calculate the thermal stability

of a composite material. AlSiC is used for both structural and

electronic applications.

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LITERATURE VIEW Mr.R.W.POWELL,D.Sc,Ph.D National Physical Laboratory,Teddington.

MAT WEBSITE for material properties.

ANSYS TUTORIAL ANSYS EUROPE Ltd

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FUTURE SCOPE OF THE PROJECT

This project can be used to find out the thermal conductivity of various materials.

This can be used to determine the thickness and bonding resistance.

This method can also be used for the identification of materials.

It will plays a vital role in thermal fields.

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TIME PERIOD PROJECT WORK

DECEMBER 2009 COLLECTION OF DETAILS

JANUARY 2010 STEADY STATE ANALSIS & COUPLED STRUCTURAL ANALYSIS

FEBRUARY 2010 TRANSIENT THERMAL ANALYSIS

MARCH 2010 DOCUMENTATION

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0% 20% 40% 60%

DEC

JAN

FEB

MAR

WORK

TIME CHART

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COST ESTIMATION DOCCUMENTATION Rs 1000

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PROJECT PLACE

A.V.C

COLLEGE

OF

ENGINEERING

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THERMAL COMPARATOR

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The Wedemkann and Franz law, regarding thermal and electrical conductivities of a material, states as follows

The ratio of thermal and electrical conductivities is the same

for all metal at the same temperature, and that the ratio is directly proportional to the absolute temperature of the metal.

Mathematically (K/σ) α T )or) (K /σ) T=C Where K= Thermal conductivity of metal at temperature T﴾k﴿, Σ = Electrical conductivity of metal at temperature T﴾k﴿, c = Constant referred as Lorenz number c = 2.45×10-8 WΩ/k² T = Temperature in k

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EXPERIMENTAL SETUP

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WORKING PROCEDURE This method is a comparative one the unknown thermal

conductivity of the material was measured with the reference of materials whose thermal conductivities are known. Such reference materials were Aluminium, Castiron, and Stainless steel.

The initial cooling rate of various materials was found out. From the initial cooling rate, material can be identified as higher thermal conductivity and lower thermal conductivity whose thermal conductivities were already known.

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THERMAL DISTRIBUTION

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PHOTOGRAPHS

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