MATERIALS SELECTIONPage *Teddy Sjafrizal @2015 MATERIALS SELECTION

by Teddy Sjafrizal

MATERIALS SELECTION

MATERIALS SELECTIONPage *Teddy Sjafrizal @2015MAIN CONSIDERATIONSThe interaction between function, material, shape, and process lies at the heart of the material selection processThe selection of a material and process cannot be separated from the choice of shape. We use the word shape to include the external, and internal, (e.g honeycomb ). To make the shape, the material is subjected to processes (e.g casting, forging, machining, polishing and joining processes)Function dictates the choice of both material and shape. Process is influenced by the material: ( formability, machinability, weld ability, heat-treatability, etc)Process interacts with shape the process determines the shape, the size, the precision and, the cost.

MATERIALS SELECTION

MECHANICAL PROPERTIESMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

MECHANICAL PROPERTIESMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

MATERIALS SELECTIONPage *Teddy Sjafrizal @2015MATERIAL SELECTION GUIDELINESS

MATERIALS SELECTION

MATERIALS SELECTIONPage *Teddy Sjafrizal @2015MATERIAL SELECTION GUIDELINESS

MATERIALS SELECTION

MATERIALS SELECTIONPage *Teddy Sjafrizal @2015MATERIAL SELECTION STEPSTRANSLATINGFunction : What does component do?Constraints : What non-negotiable conditions must be met?What negotiable but desirable conditions ?Objective : What is to be maximized or minimized?Free variables : What parameters of the problem is the designer free to change?SCREENING : eliminates candidates that cannot do the job at all

MATERIALS SELECTION

MATERIALS SELECTIONPage *Teddy Sjafrizal @2015MATERIAL SELECTION STEPSRANK : measure how well a candidate that has passed the screening step can do the job. Performance is sometimes limitedby a single property, sometimes by a combination of themSUPPORTING INFORMATION : it is descriptive, graphical or pictorial, details of its corrosion behavior in particular environments, information of availability and pricing, experience of its environmental impact

MATERIALS SELECTION

CASE STUDYMATERIALS SELECTIONPage *Teddy Sjafrizal @2015Known : The heat sink must be a good electrical insulator, meaning a resistivity e > 1019 .cm. But to drain heat away from the chip as fast as possible, it must also have the highest possible thermal conductivity, .Translating .

FunctionHeat SinkConstraintsMaterial must be good insulator, or e > 1019 .cmAll dimensions are specifiedObjectiveMaximize thermal conductivityFree variablesChoice of Material

MATERIALS SELECTION

CASE STUDYMATERIALS SELECTIONPage *Teddy Sjafrizal @2015Screen : Resistivity e > 1019 .cm.Rank : Maximum thermal conductivity.Result : Aluminium Oxide

MATERIALS SELECTION

MATERIAL INDICESMATERIALS SELECTIONPage *Teddy Sjafrizal @2015Material indices when objectives are coupled to constraints.

MATERIALS SELECTION

MATERIALS SELECTIONPage *Teddy Sjafrizal @2015A schematic E- chart showing guidelines for the three material indices for stiff, lightweight design.

MATERIALS SELECTION

MATERIALS SELECTIONPage *Teddy Sjafrizal @2015CASE STUDYMinimize massMaximize slenderness

FunctionColumn (supporting compressive loads)ConstraintsLength L specifiedMust not buckle under design loadsMust not fracture if accidentally struckObjectiveMinimize the mass, m Maximize slendernessFree variablesDiameter of legs, 2rChoice of material

MATERIALS SELECTION

PROCESS SELECTIONMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

PROCESS SELECTIONMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

FunctionWhat must the process do ? Shappe? Join ? Finish ?ConstraintsWhat material, shape, size, precision , must it provide ? ObjectiveWhat is to be maximed or minimized ? ( cost ? Time ? Quality ? )Free variablesChoice of processProcess chain options

MATERIALS SELECTION

PROCESS SELECTIONMATERIALS SELECTIONPage *Teddy Sjafrizal @2015Case study : Forming a FANResult

FunctionFanConstraintsMaterial : NylonShape : 3D solidMass: 0.1 -0.2 kgMinimum section : 4 mmPrecision : 0.5mmRoughness : < 1 mBatch size : 10,000ObjectiveMinimize costFree variablesChoice of process

ProcessCommentInjection MoldingMeets all design constraintsCompression moldingMay need further finishing operations

MATERIALS SELECTION

The processmaterial compatibility matrixMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

The processshape compatibility matrixMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

The processmass range chartMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

The processsection thickness chartMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

The processtolerance chartMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

The processsurface roughness chartMATERIALS SELECTIONPage *Teddy Sjafrizal @2015

MATERIALS SELECTION

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