2009-2010 FINAL YEAR PROJECT DEPARTMENT OF MECHANICAL ENGINEERING A.V.C COLLEGE OF ENGINEERING
16TH APRIL 2010 PROJECT PRESENTATION FINAL YEAR PROJECT
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)
CONTENT • INTRODUCTION • PROJECT TITLE • INTRODUCTION • PROBLEMS • OBJECTIVES • EXPERIMENTAL METHOD • TECHNICAL VIEWS • METHODOLOGY • COMPARISON OF RESULTS • APPLICATIONS • LITERATURE VIEW • PROJECT STATUS CONTENT
ANALYSIS OF THERMAL CONDUCTIVITY AND THERMAL STRESS ON ALUMINIUM SILICONCARBIDE COMPOSITES
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.
THERMAL CONDUCTIVITY • 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
REGARDING THERMAL CONDUCTIVITY • 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.
THERMAL STRESS • Stress introduced by uniform or non uniform temperature change in a structure or material which is constrained against expansion or contraction.
COMPOSITE MATERIAL • 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.
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.
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.
PROJECT VIEW REFER THE READINGS FROM EXPERIMENTAL METHOD TRANSFER THE READINGS TO ANALYSIS METHOD THERMAL STRESS ANALYSIS TRANSIENT STATE ANALYSIS USING ANSYS & HYPERMESH COUPLED STRUCTURAL ANALYSIS GRAPHICAL METHOD
REFERENCE • PROJECT TITLE “DETERMINATION OF THERMAL CONDUCTIVITY OF COMPOSITE MATERIALS” • MECHANICAL DEPARTMENT • BATCH 2005-2009
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.
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.
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%).
COOLING RATE Vs THERMAL CONDUCTIVITY AlSiC (SiC 5%) Cooling Rate (µv) Thermal Conductivity (W/mK) [v ] COOLING RATE thermal conductivity 151.67 W/mK
SPECIMEN • 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
TECHNICAL VIEWS • HYPER MESH For modelling and meshing the material • ANSYS Steady state thermal analysis Transient thermal analysis Coupled structural analysis
THERMAL ANALYSIS • TYPES STEADY STATE THERMAL ANALYSIS TRANSIENT THERMAL ANALYSIS
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.
HYPER MESH- PROCEDURE • Create a profile. • Choose element – SHELL 57. • Apply the values. • Mesh the element. • Export the values from hyper mesh to ansys.
ELEMENT FOR THERMAL ANALYSIS • 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 STRUCTURAL ANALYSIS • 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.
COUPLED STRUCTURAL ANALYSIS , "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-PROCEDURE • Thermal Environment - Create Geometry and Define Thermal Properties • Give a Title • Utility Menu > File > Change Title .../title, Thermal Stress Example • 2.Open preprocessor menu • ANSYS Main Menu > Preprocessor/PREP7 • 3.Define Keypoints • Preprocessor > Modeling > Create > Keypoints > In Active CS...K,#,x,y,z
4.Create Lines Preprocessor > Modeling > Create > Lines > Lines > In Active cs 5.Define the Type of Element Preprocessor > Element Type > Add/Edit/Delete...
Define Real Constants • Preprocessor > Real Constants... > Add... • In the 'Real Constants for LINK33' window, enter the following geometric properties: • Define Element Material Properties • Preprocessor > Material Props > Material Models > Thermal > Conductivity > Isotropic
MODELLING IN HYPER MESH SPECIFICATION OF SHELL L=150mm;B=50mm;T=10mm
PROPERTY VALUES • Young’s modulus1.15*e5 N/mm2 • Poisson’s ratio 0.3 • Density 2.88*e-9 t/mm2 • Thermal expansion 0.000015mm/0 C
Define Mesh Size Preprocessor > Meshing > Size Cntrls > ManualSize > Lines > All Lines... Mesh the frame Preprocessor > Meshing > Mesh > Lines > click 'Pick All' Write Environment The thermal environment (the geometry and thermal properties) is now fully described and can be written to memory to be used at a later time
Preprocessor > Physics > Environment > Write In the window that appears, enter the TITLE Thermal and click OK. Clear Environment Preprocessor > Physics > Environment > Clear > OK
Structural Environment - Define Physical Properties Since 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 Type Preprocessor > Element Type > Switch Elem Type Choose Thermal to Struc from the srcoll down list.
Define Element Material Properties Preprocessor > Material Props > Material Models > Structural > Linear > Elastic > Isotropic The properties are from mat website density-2.88*10^-9 t/mm^2 E=115 Gpa
Write Environment • The structural environment is now fully described. Preprocessor > Physics > Environment > Write • In the window that appears, enter the TITLE Struct Solution Phase: Assigning Loads and Solving Define Analysis Type Solution > Analysis Type > New Analysis > StaticANTYPE,0 Read in the Thermal Environment Solution > Physics > Environment > Read Choose thermal and click OK.
Apply Constraints • Solution > Define Loads > Apply > Thermal > Temperature > On Keypoints • Solve the System • Solution > Solve > Current LSSOLVE • Close the Solution Menu • Main Menu > Finish
Read in the Structural Environment Solution > Physics > Environment > Read Choose struct and click OK. Apply Constraints Solution > Define Loads > Apply > Structural > Displacement > On Keypoints Include Thermal Effects Solution > Define Loads > Apply > Structural > Temperature > From Therm Analy
Define Reference Temperature Preprocessor > Loads > Define Loads > Settings > Reference Temp • Solve the System • Solution > Solve > Current LSSOLVE