Selection and Production of Materials Flashcards
Name there 4 families of engineering materials.
Metals
Ceramics
Glasses
Polymers & elastomers
6 types of materials properties
General Mechanical Thermal Electrical Magnetic Optical Environmental/Chemical
Effect of bonding on yield strength
Increasing directionality of bonding leads to increased yield strength and hardness.
What are engineering materials a function of (2 things)?
Raw materials
Processing history
Outline the design process
Pick application
Determine the required properties
Identify candidate materials
Identify required processing
Four steps for materials selection.
TRANSLATION of design requirements
SCREENING using constraints
RANKING using the objective
SUPPORTING INFORMATION
Four parts of TRANSLATION
Function
Objective
Constraints
Free variables
A performance equation is made of functions that represent what 3 things?
Functional requirements, geometry and material properties
How do you identify a material when there are multiple constraints?
Solve each constraint individually
Select candidates based on each constraint
Evaluate performance using each constraint
Select performance based on the most limiting.
What is a composite?
A reinforced matrix usually to modify mechanical properties of a material.
Common themes of composites.
Multiple phases present
Interfaces between phases
Need to control structure and anisotropy of the phases - processing challenges
Multiple length scales
Three main types of polymers.
PMCs
CMCs
MMCs
Examples of PMCs
CF/poxy (prosthetics)
Powdered ferrite and rubber (fridge magnets)
PZT in thermoplastic (piezoelectric transducers)
Benefits of thermoplastic PMCs
Cheapest processing
Benefits of elastomer PMCs
Elastomeric mechanical properties
Benefits of thermosetting PMCs
Stiff
Higher T resistance
Low viscocity precursor
Ceramic fibres/parrticles in MMCs improve what properties?
High T strength
Creep resistance
Wear resistance
Can tailor thermal expansion
Which metals are the usual matrices in MMCs?
Al, Mg or Ti
Applications of MMCs
Engine pistons (Al + Al2O3)
Aeroengine fan blades (Ti + SiC monofilament)
Brake discs (Al-Si + SiC particulate)
Conducting cable core (Al + Al2O3)
What is a cermet?
Typically ceramic with possiblity of plastic deformation. Ususally <20% metal by volume.
CMC examples
Concrete/reinforced concrete
Zirconia toughened alumina grinding balls
Hypersonic aeroshells (C/SiC, C/C, SiC/SiC)
Brake discs (CF reinforced SiC)
What is a 0.5D fibre?
Chopped fibre in composite.
Examples of linear composites.
Plywood
Insulation panel
CF weave
Write the full stacking sequence of this:
[(±45/(0)2/(90)2)2]s
Derive the max fibre packing ration in particulate composite and a fibre matrix.
Check
Volume fraction of fibres in hexagonal and square lattice eqns.
Check
Seperation of fibres in hexagonal and square lattice equations
Check
What is E-glass?
Electrical, good insulator and strength
What is C-glass?
Corrosion resistance
What is S glass?
Higher cost that E, higher strength and high T properties.
Examples of heirarchical structures.
Wood, bone
What is a metamaterial?
A material manufactured with repeating hierarchical structures.
What are the five different types of interface bonding mechanisms?
Interdiffusion & chemical reaction Electrostatic attraction Residual stress Mechanical keying Adsorption & wetting
