Material Properties Material properties 1 Physical properties Quantities

Material Properties

Material properties 1. Physical properties Quantities that characterize the behavior of a material in response to physical phenomena other than mechanical forces …(e. g. such as heat, electricity, radiation) 2. Chemical properties Quantities that characterize the behavior of a material in response to other chemicals in its environment 3. Mechanical properties Quantities that characterize the behavior of a material in response to external, or applied forces

Physical properties • color –light wave length • specific heat – the heat required to raise the temperature of one gram of a substance by one degree celsius (J/kg K)

Physical properties • density – mass per unit volume expressed in such units as kg/cm 3 • thermal conductivity –rate at which heat flows through a given material (W/m K)

Physical properties • melting point – a temperature at which a solid begins to liquify • electrical conductivity – a measure of how strongly a material opposes the flow of electric current (Ω⋅m)

Physical properties • coefficient of thermal expansion – degree of expansion divided by the change in temperature (m/°C)

Chemical properties • corrosion resistance - a material's ability to resist deterioration caused by exposure to an environment • Byproducts resulting from decay- if the material decays, what are the resulting chemicals

Mechanical properties • Compressive stress (or compression) is the stress state caused by an applied load that acts to reduce the length of the material (compression member) in the axis of the applied load, in other words stress state caused by squeezing the material. • Tensile stress is the stress state caused by an applied load that tends to elongate the material in the axis of the applied load, in other words the stress caused by pulling the material. • Shear stress is the stress state caused by the combined energy of a pair of opposing forces acting along parallel lines of action through the material, in other words the stress caused by faces of the material sliding relative to one another. An example is cutting paper with scissors.

Mechanical properties • Deformation of the material is the change in geometry created when stress is applied • Strain or reduced deformation is a mathematical term that expresses the trend of the deformation change among the material field. Strain is the deformation per unit length. • Deflection is a term to describe the magnitude to which a structural element bends under a load.

Mechanical properties • ductility – a measure of how much strain a material can take before rupturing • malleability – the property of a material that can be worked or hammered or shaped without breaking • brittleness –breaking or shattering of a material when subjected to stress (when force is applied to it)

Mechanical properties • elasticity – the property of a material that returns to its original shape after stress (e. g. external forces) that made it deform or distort is removed • plasticity - the deformation of a material undergoing non-reversible changes of shape in response to applied forces

Mechanical properties • toughness – the ability of a material to absorb energy and plastically deform without fracturing • hardness – the property of being rigid and resistant to pressure; not easily scratched • machinability – the property of a material that can be shaped by hammering, pressing, rolling

Forming Processes: Forging - a manufacturing process where metal is shaped by plastic deformation under great pressure into high strength parts. Casting – pouring or injecting molten metal into a mold containing a cavity with the desired shape

MATERIALS` PROPERTIES MALLEABILITY - if a material can be TOUGHNESS deformed in all directions by such as hammering and pressing without it cracking or splitting it is said to be malleable. These materials need not be strong but they need to be 'plastic'. That is they need to be able to be bent often without breaking. Lead is a good example of a metal which is malleable. The ability to withstand sudden shocks or blows without it fracturing. It can also be applied to the ability of a material to withstand cracking if it is subjected to bending forces or shear forces. BRITTLENESS This is the opposite of toughness. Materials that are brittle cannot withstand any strain before they crack or break. Two good examples of this type of material would be acrylic and glass. STABILITY Materials which are stable resist changes in size and shape, which can often be caused by weather, particularly wet or dry conditions. Wood tends to warp and twist if it gets too wet or dry. Plastic tends to bend and stay bent if it is subject to constant force. This stretching due to force is called 'creep'. It is most important that certain objects such as turbine blades resist 'creep' because they are subjected to a lot of rotational force and high temperatures which are known to cause 'creep'. DUCTILITY - usually means the ability of a material to be stretched twisted or bent without breaking. All ductile materials are malleable but all malleable materials are not necessarily ductile. For example clay can be easily shaped but when you try to stretch it, it breaks. ELASTICITY - the ability to flex and bend when forces are applied and then return to normal when the forces are removed (eg. an elastic band). HARDNESS Any material which can resist wear and tear, denting and twisting and bending is said to have the quality of hardness. Drills, files emery cloth and glasspaper have these qualities.

What Materials to Choose From?

Material families / subfamilies Materials Metals Ferrous Non-ferrous Plastics Ceramics Thermoplastics Thermosets Elastomers Sub-family Composites Family (Ashby)

Material sub-families / classes Materials Metals Ferrous Cast iron Carbon steel Alloy steel Stainless steel Family Sub-family Classes

Metals Ferrous cast iron carbon steel alloy steel stainless steel Non-ferrous aluminum brass bronze copper lead magnesium nickel tin titanium tungsten zinc

Polymers Natural and synthetic rubbers Polymers Thermoplastics ABS acetal acrylic nylon polycarbonate polyethylene polypropylene polystyrene vinyl Thermosets alkyd epoxy melamine phenolic polyester urethane Elastomers butyl fluorocarbon neoprene nitrile polysulfide rubber silicone

Polymers No chemical reaction Cross-linking

Ceramics alumina beryllia diamond magnesia silicon carbide silicon nitride zirconia

Composites carbon fiber ceramic matrix glass fiber Kevlar metal matrix

Composites Manufacturing process Carbon fiber Style 282 bidirectional. Araldite epoxy resin with HY 956 additive.

Composites College Park Foot Otto Bock Advantage Ossur Flexwalk Pie protésico dinámico 2004 Pie protésico dinámico 2005

Composites Date of birth: April 21, 1978 Hometown: Thatcher, Utah Current Home: San Diego, CA Marlon Shirley Cameron Clapp Ossur Cheeta Flex-Foot Otto Bock C-Leg Date of birth: Sep 15, 1986

Property profiles by family

Materials selection prospective materials and processes functional? manufacturable? relative performance? screening feasible materials and processes rating best material(s) and processes rejected materials and processes

Screening: Materials first approach Application Information 1. Applied loads magnitude cyclic nature (steady, fatigue) rate (slow, impact) duration (creep) 2. Ambient conditions temperature moisture sunlight chemical liquids/vapors 3. Geometry of end product 4. Safety 5. Cost

Rating: Material indices • Given the same cost/volume… which is stronger? index = Strength/cost • Given the same cost/volume… which is stiffer? index = Young’s modulus/cost

Ashby Chart How can we use it?

Which properties do the following materials possess? Material aluminium rubber ceramics steel copper lead nylon cast iron wood Properties

Which properties do the following materials possess? Material Properties aluminium lightness ; strength rubber elasticity ; insulation ceramics thermal resistivity steel strength copper conductivity ; corrosion resistance lead high density; ductility nylon strength ; toughness cast iron damping capacity wood insulation ; environmental friendliness

Find application for the following engineering materials: Material aluminium rubber ceramics steel copper lead nylon cast iron wood Application

Find application for the following engineering materials: Material Application aluminium foil; aircraft; window frame rubber tyres, ; seal; gasket ceramics furnace; brick steel section; pipe copper pipe; cables lead storage battery; radiation protection ballast; bullets nylon rope; clothing cast iron engine block; valves wood furniture; deck

Some of the strongest materials Material Tensile Strength UTS (Ultimate Tensile Strength) carbon nanotubes 62000 MPa (theoretical 300000 MPa) 48000 k. Nm/kg carbon fibre 5650 MPa 3200 k. Nm/kg glass fibre 4700 MPa 1340 k. Nm/kg spider web 1000 MPa 900 k. Nm/kg high-strength steel 1200 MPa 154 k. Nm/kg

Some of the best conductors Material silver copper gold aluminium Conductivity 63 x 106 S/m (1/ohm) 59. 6 x 106 S/m (1/ohm) 45. 2 x 106 S/m (1/ohm) 37. 8 x 106 S/m (1/ohm)

Some of the best insulators Material Specific resistance polyethylene terephthalate (PET) 1020 ohm glass 1014 ohm rubber 1013 ohm

Materials with the greatest densities gold - 19300 kg/m 3 uranium - 19100 kg/m 3 lead - 11340 kg/m 3 steel - 7800 kg/m 3