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What is tensile strength?
the ability to resist stretching or pulling forces
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How do you test for tensile strength in a workshop?
clamp materials of same length and thickness into a vice, apply load at unclamped end, less deflection under load more tensile strength material has.
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What is toughness?
How much impact force material can absorb
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How do you test for toughness in a workshop?
clamp material in vice, samples hit with same force using hammer, tough materials absorb imapct, brittle ones bend/shatter.
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What is hardness?
abrassive wear & resistance to surface indentation.
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How do you test for hardness (abrassive wear) in a workshop?
run a file over surface of material, fewer scratches harder material.
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How do you test for hardness (indentation) in a workshop?
place dot punch on surface of material, hit dot punch with hammer, smaller indent harder the material.
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How do you test for malleability and ductility?
secure test piece in vice, try and bend to 90 degrees, if material cracks on outside indicates lack of ductility, if material cracks on inside indicates lack of malleability.
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What is corrosion?
effects of being exposed to environment
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How do you test for corrosion in a workshop?
place material outside exposed to weather. After certain length of time inspect for corrosion.
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How do you test for electrical conductivity in a workshop?
place probes a set distance apart on material. Measure resistance on multimeter, higher resistance lower conductivity.
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How do you test for thermal conductivity in a workshop?
place thermometer at one end of material and bunsen burner at the other, light bunsen and time how long it takes for materialto heat up at other end. shorter time higher thermal conductivity.
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How do you test for tensile strength in industry?
place material on tensometer machine, hold each end in clamps, 1 fixed and 1 that moves on worm drive gear mechanism. As worm drive travels as constant rate material is put under tension. as test piece is stretched load and distance travelled plotted
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How do you test for toughness in industry?
Izod imapct test. Notched test piece held vertically in vice machine, pendulum released from set height, swings to hit material. energy absorbed calculated from height of pendulum at beginning to end. More impact absorbed tougher.
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How do you test for hardness in industry using rockwell test?
pre load (datum) applied to material using diamond indenter which breaks through surface. additional load is applied and held for set time (dwell time), load is released. Distance between pre load and applied load is measured.
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how do you test for hardness using the brinell test in industry?
hardened standard size steel ball forced into material using preload. diameter of indent is measured, smaller indent harder material.
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How do you test for hardness in industry using Vickers pyramid?
diamond square based pyramid to indent surface, diamond will not deform under load. Microscope measures size of indent.
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How do you test for malleability and ductility in industry?
test piece is placed in bending machine, held and supported at either end. a mandrel loads test piece at centre and bends it to a predetermined angle or until fracture. material inspected for for cracks and defects.
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what are the two types of non destructuve testing and when is it used?
ultrasonic and x-ray. used on products such as large castings where there is a liklihood of internal defects.
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How do you test a material for defects using ultrasonic testing?
transducer generates sound waves. intensity of reflected sound waves is recored on display unit. waves travel through material and are partially reflected if there are any defects.
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Why is ultrasonic testing good and what is it used for?
can be performed on all types of materials, portable, high accuracy. used widely in offshore and aerospace industries, commonly used to check quality of welds in pipes.
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how do you test a material using x-ray testing?
x-ray beam passes through material and image projected onto display screen. due to x-rays ability to see tiny details, magnified image enables minute flaws such as hairline cracks to be detected.
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what is x-ray testing used for?
inspect integrated circuits and PCBs, checks for micro voids in composite materials such as formular 1 cars, detect faults in turbine blades.
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How do you test for electrical conductivity in industry?
4 wires stretched parellel to each other across non conductive polymer block, held in place, connected to copper terminal blocks. 2 leads attached to inner wires, 2 to outer. outer leads connected to precise current, 2 inner leads measure voltage.
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How do you measure thermal conductivity in industry?
using heat flow meter, square shaped material placed between 2 temp controlled plates. temp increased at controlled rate, heat flow through material measured by heat flow sensors that record conductivity.
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why is melamine formaldehyde good for a kitchen worktop?
thermosetting, high melting point, not dmaged from hot surfaces. chemical resistant, cleaned with detergent. hard, won't scratch, pigmented for colour
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Why is neoprene a good elastomer for a wet suit?
stretch and release for tight fit, degradation resistant, not damaged by salt water pigmented for colour, give consumer choice/ company logo
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What are paper and boards?
compliant materials, scored, folded, cut. commonly used for packaging
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Name examples of different papers and boards.
layout, cartridge, tracing, bleedproof, water colour paper. corrugated, bleeched, foil backed, laminated card. moulded paper pulp
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Why is corrugated card a good material for a pizza box?
compliant easy to cut/fold for box shape usinf die cutter. food safe doesn't contaminate pizza. insulating due to air pockets. lightweight easy to carry. easily recycled no contribution to landfill. Biodegradable.
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What are composites?
two or more different materials for enhanced properties
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Name examples of compostie materials.
fibre based- CFRP, GRP. partical based- tungsten carbide, concrete. sheet based- aluminium composite board, engineered wood: gluam
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Why is GRP a good material for a boat hull?
manufactured via the lay up method allowing complex 3D shapes. pigmented for colour, improved aesthetics/ branding. chemical resistant, won't corrode/ decayin saly water. tough, withstand minor imapct.
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What is a smart material?
physical properties change in repsonse to an input or change in external environment.
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Give examples of smart materials.
shape memory alloy, thermochromic pigment, thermochromatic film, phosphorescent pigment, electroluminescent wire, piezo electric material.
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Why is thermochromatic film used in thermometers?
changes in colour in response to temperature, colour changes makes it easier to read than small numbers/ lines. non toxic, safer to use than mercury. when incorporated into film flexible enough to put in forehead.
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What are modern materials? Give some examples.
developed through invention of new or improved process. kevlar, PMC, high density modelling foam, polymorph
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Other cards in this set

Card 2

Front

How do you test for tensile strength in a workshop?

Back

clamp materials of same length and thickness into a vice, apply load at unclamped end, less deflection under load more tensile strength material has.

Card 3

Front

What is toughness?

Back

Preview of the front of card 3

Card 4

Front

How do you test for toughness in a workshop?

Back

Preview of the front of card 4

Card 5

Front

What is hardness?

Back

Preview of the front of card 5
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