Materials Selection in Mechanical Design

Aim of the course

nTo provide the student with the skills to select via systematic and objective procedures the best material and process in mechanical design issues

n

nTo train the students in the use of such tools. 

Mechanical Design

Mechanical components :

n- have mass

n- carry loads

n- conduct heat and electricity

n- exposed to wear and corrosion

n- are made of materials

n- have a shape

n- must be manufactured 

Inter- relations

  

Evolution of Engineering Materials

 

The Design Process

nTo develop a methodology for selecting materials and processes which is design led, i.e. the design uses as inputs the functional requirements of the design.

The design process

 A technical system

A systems approach

 

Types of design

nOriginal design

n

nAdaptive or development design

n

nVariant design

Design Methodology

 

Function analysis

How to open a corked bottle ?

 

Working principles

 

Function structure and working principles of cork removers

 

Realisation

 

Conclusion

nDesign is an iterative process

nIt starts with a need statement

nThe a concept is devised

nAn embodiment is envisaged and detailed

nThe embodiment is refined on the basis of ever more refined data 

Engineering materials and their properties

nClasses of materials

n

nIntrinsic or atom related material properties

n

nTailored or microstructure related properties

n

nNon-mechanical properties, such as cost 

Engineering material families

 

Definition of properties in units

nDensity  (kg/m3)

nElastic moduli  (GPa)

nFracture strength  (MPa)

nResilience (J/m3)

nHardness  (GPa)

nToughness (MPa.m1/2)

nLoss coefficient (-)

nThermal conductivity (W/mK)

n

n

  

Shapes of stress strain curves

Material properties (continued)

 

MATERIAL SELECTION CHART  (Bubble chart)

 

Material Property Charts

 

n

n

Recapitulation

nDesign cycles from function analysis to embodiment to design

n

nMaterials selection on properties

n

nA cyclic loop