Topic 4 - pt.1 Flashcards
list the physical properties
- mass
- weight
- volume
- density
- electrical resistivity
- thermal conductivity
- thermal expansion
- hardness
list the mechanical properties
- tensile and compressive strength
- stiffness
- toughness
- ductility
- elasticity
- plasticity
- Young’s Modulus
- stress
- strain
list the aesthetic characteristics
- taste
- smell
- appearance
- texture
list the properties of smart materials
- piezo electricity
- shape memory
- photocromocity
- magneto-rheostatic
- electro-rheostatic
- thermoelectricity
mass definition
amount of matter contained in a space
weight
a force measured in Newtons (changes w gravity)
volume
amount of 3-dimensional space taken up
density
the relationship between mass and unit of volume (mass/volume)
electrical resistivity
a material’s ability to conduct or resist electricity
thermal conductivity
a measure of how fast heat moves through the material
thermal expansion
the degree to which a material increases in its dimensions due to heat
hardness
the resistance of a material to scratching or penetration
tensile strength
ability of a material to withstand pulling forces
- important for selecting materials for ropes and cables
compressive strength
ability of a material to withstand being pushed or squashed
- important for selecting materials for structures e.g. pillars
stiffness
the resistance of an elastic body to deflection by an applied force
toughness
the ability of a material to absorb energy and plastically deform without fracturing
- (a material’s resistance to fracture when stressed)
plasticity
ability of a material to be changed in shape permanently by external blows or pressure without cracking or breaking
stress
the force per unit area of a material
- normally determined by applying a tensile force to material
strain
after a tensile force is applied to a material it’s expected to be elongated
Young’s Modulus
measure of stiffness of an elastic material –> ratio of stress along an axis to the strain
photo-chromocity
material that can be described as having a reversible change of colour when exposed to light
thermoelectricity
generated by a device that converts heat and the temp difference between materials into electricity
magneto-rheostatic
fluids which can experience a dramatic change in consistency when exposed to a magnetic or electric field
- e.g. thick fluid to solid really quickly
piezo electricity
squeeze or pressure giving off a small electrical discharge
shape memory
metals that have a rearrangement of the molecules in the material due to changes in temp
composite materials
materials made from two or more materials with different physical or chemical properties –> when combined produce a material w different characteristics from original
- this is done to make materials stronger, lighter, or less expensive
advantages of composite materials
- high strength to weight ratio
- high tensile strength
- when weaving it can produce a prettier look
- (weaving) different materials can be chosen to make it more strong or stiff
disadvantage of composites
- very expensive
- requires specific manufacturing facilities
- weak when compressed or squashed
- air bubbles will cause weak spots and reduce overall impact
- difficult or can’t be recycled
plywood
- manufactured from an uneven number of plys
- needed where high quality, high strength, and large sheet material is required
- resistant to cracking, breaking, shrinkage, and twisting
- can be used as an engineering material for architecture or marine environments
laminated glass
- consists of a sandwich of glass-polymer(PVB)-glass stuck with heat and pressure in autoclave
- when broken the PVB layer holds the pieces of glass together (safer)
- used for car windshield
- the fracture produces spider-web pattern crack
laminar composites
- laminates of different materials joined together in sandwich structure
- a layer of thin bidirectional fibers/metal sheets held apart by a lightweight core
weaving
forms fabric by interlacing long threads passing in one direction with others at a right angle to them (bidirectional)
pultrusion
continuous moulding process making sure fibers are saturated with a liquid polymer resin and carefully formed and pulled through a heated die to form a part
lamination
assembling individual sheets of materials into a multilayered material or component with heat and pressure
spray-up
carried out on open mould where both the resin and reinforcements are sprayed directly onto mould
how is concrete made
- sand, concrete, aggregate, and water to form a fluid mass that is easily moulded –> becomes hard and solid after drying
- aim is to increase strength
how is engineered wood made
- binding or fixing strands, particles of fibers, veneers of boards of wood together with adhesive
- used for medium-density fireboard, plywood, chipboard
how is plywood made
- sheet material that is manufactured from thin layers or “plies” of wood veneers that are glued together with adjacent layers
- used for wall panelling, flooring, and furniture
how is particleboard made
- (chipboard) is an engineered wood product made from wood chips, sawmill shavings or sawdust, and synthetic resin
what is kevlar
- woven into a cloth which combined with polyester resin can be moulded into different shapes
- can also be woven into fabric cloth to protect wearer
- has high strength-to-weight ratio –> 5 times stronger than steel
- used for body protection (bulletproof vest), helmets, sports equipment (skis), racquets, sails for windsurfing
how is carbon-reinforced plastic (GRP) made
- made from plastic and fibreglass
- can easily be moulded into 3D shapes, versatile, good strength-to-weight ratio
- used for boat hulls, canoes, car body panels, chemical storage tanks, and train canopies
how is laminated veneer lumber (LVL) made
- uses multiple layers of thin wood assembled with adhesives
- used for headers, beams, rim boards, edge-forming material
SP: one-off
- used when only one for a few specialist items is required –> produces a single product
- advantages: unique and high-quality products are made, workers are motivated and take pride in their work
- disadvantages: labour intensive so prices are high, production can take a long time and expensive from using specialist tools
SP: batch production
- a set number of items to be produced
- advantages: unit costs are lower since large numbers are made, offers curtomers variety and choice, materials can be bought in bulk so cheaper
- disadvantages: workers less motivated since work is repetitive, goods have to be stored until they’re sold which can be expensive
SP: mass and continuous flow
- Mass: production of large amounts of standardized products on production lines –> high rates of production per worker
- Continuous Flow: PM used to manufacture/produce/process materials without interruption
- advantages: labour costs low, materials can be purchased in large quantities so cheaper, large number of goods are produced
- disadvantages: machinery expensive to buy and set up, workers not motivated, not flexible bc production line is difficult to adapt, production process has to be stopped when repairs are made
SP: mass customization
- a CIM system that manufactures products to individual customer orders
- mass customization uses techniques from mass production; its output is based on core components
