Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
DT 1.1
DT Summer Y12
| Question | Answer |
|---|---|
| Compressive strength definition | Ability to withstand being crushed/shortened by pushing forces |
| Tensile strength definition | Ability to resist stretching/pulling forces |
| Shear strength definition | Ability to resist sliding forces on a parallel plane |
| Torsional strength definition | Ability to withstand twisting forces from applied torque or torsion |
| Hardness definition` | Ability to resist abrasive wear (such as scratching, surface indentation, or cutting) |
| Toughness definition | Ability to absorb impact force without fracture |
| Plasticity definition | Ability to be permanently deformed and retain the deformed shape |
| Ductility definition | Ability to be drawn out under tension, reducing the cross-sectional area without cracking |
| Malleability definition | The ability to withstand deformation by compression without cracking. Increases with a rise in temperature. |
| Thermal expansion definition | Increase in material volume in response to heat input |
| Translucent definition | Allows light through but diffuses the light so that objects appear blurred |
| Fusibility definition | Ability to be fused or converted from a solid to a liquid/molten state, usually by heat. Essential for casting metal. |
| Magnetism definition | The natural force between objects that causes the material to attract iron/steels |
| Corrosion/degradation resistance definition | Ability of the material to withstand environmental attack and decay |
| Talking about using plastic instead of galvanised metal for a watering can | Scratches harder to get but degrade the underlying iron. Plastic is pigmented during manufacture and can be easily changed e.g. to show a can containing herbicide as red not green. Mild steel cheaper than HDPE but not just one step to make: costly |
| PET bottles suitability | Toughness so droppable. Thermoplastic so recyclable, which ensures the single-use product wont end up in landfill. Impermeable to CO2 for carbonated. Available in transparent so can see how much drink left |
| MF suitability for kitchen counter | High melt for pans Chem resist for detergent cleaning Hard so can use scouring pad Pigmented so fits kitchen aesthetics |
| Neoprene suitability for wetsuit | Elastomer so stretch and release to fit tightly Good degradation resist so not damaged by salt water Pigmented for colour choice or company brand colour |
| Corrugated card suitability for pizza box | Compliant and easy to cut with die cutter Food safe Insulating air pockets in corrugations Lightweight so easy on delivery bike Single use - is easy recycled so not in landfill. Even if thrown away, biodegradable. |
| Compliant definition | Can be scored, folded, and cut with basic tooling to form items such as nets for packaging. |
| Thermoplastic definition | Can be repeatedly reheated and reshaped. Long linear chain molecules held by van der Walls forces. |
| Thermosetting polymer definition | When heated undergoes chemical change with molecules forming rigid cross links. Cannot be reheated and reshaped, even at very high temps. |
| Elastomer definition | At room temp can be deformed under pressure and then upon release of the pressure will return to original shape. Weak bonds allowing repeated stretching, then returning with force to original length. |
| Composite definition | Material comprised of 2+ different materials, resulting in material with enhanced properties |
| Manufactured board definition | Man-made wood-based composite board |
| GRP suitability for boat hull | Lay-up method so can be made into complex 3D shape such as the hull Pigmented for aesthetics/corporate branding Chemical resistance so not corroded/decayed in salt water Tough material so can withstand minor impact from waves without damage |
| Smart material definition | Material whose physical properties change in response to an input/change in environment e.g. electricity, pressure, temperature, light |
| Why thermochromatic film suitable for thermometers | Changes colour in response to temp change Colour change e.g. red for hot means easier to read than small number/lines on traditional Non-toxic so safer than mercury for e.g. young children |
| Modern material definition | Material developed through invention of new/improved processes e.g. as a result of man-made materials or human intervention |
| Why aluminium good for recycling | Low melting point for a metal |
| Workshop test for hardness | Dot punch depth/size same force while fully supported underneath. Smaller indent harder. Hit once - resistance to surface indentation. Also run file over it - least scratches - abrasive wear |
| Workshop test for toughness | Vice hammer hit same force - does it shear, break, bend, etc |
| Workshop test for tensile strength | Clamp horizontally with same mass on unclamped end. Tension on top surface and compression on bottom surface. Does it bend (how much does it deflect)? How does it act if bent? |
| Workshop test for malleability and ductility | Clamp vertically and try to bend piece 90 degrees. Long surface ductile. Short inside surface malleable (may also apply to outside, but picture crushing a coke can). Look for cracks/surface damage. |
| Workshop test for corrosion | Visual check after being left outside in weather for time. Could then follow with toughness/hardness test. |
| Workshop test for conductivity | Mark set distance for probes of multimeter, giving resistance (opposite to conductivity). For temperature, set distance of thermometer from bunsen under end of material. Time to reach set temp - less time more conductive |
| Considerations for tests | Same dimensions. Same force. Same times. Repeat measurements. Same environmental conditions. Same testing equipment. Same position of force application. |
| Difference between industrial and workshop test results | Workshop tests are comparative while industrial tests are scientific. |
| Industrial test for tensile | Standard test piece in tensometer machine. Clamps at each end - one moves on worm drive gear mechanism, travelling at constant rate. Load and distance travelled plotted, showing elastic limit, yield point, max load, final breaking point after 'necking' |
| Diagram for tensile strength industrial test | Grips holding test piece inside metal frame. Spring beam on fixed side with rubber buffers on the very outside for recoil. Moving side has thread near the end and goes to worm drive. |
| Industrial test for toughness | Izod impact test. Notched test piece vertically clamped. pendulum released from set position to strike. Energy absorbed by test piece calculated from height the pendulum swings to after it hits. Most absorption is the toughest (least brittle) |
| 3 different types of Industrial test for hardness | Rockwell, Brinell, Vickers pyramid |
| Rockwell test | Preload applied to material using diamond indentor: breaks through just the surface of the material - reference position. Additional load then applied and held for predetermined 'dwell time'. Released. Distance between preload and applied load measured |
| Brinell test | Hardened standard size steel ball forced into material surface using pre-set load. Diameter of indent measured. |
| Vickers pyramid test | Used for very hard materials. Diamond square-based pyramid to indent surface. Diamond won't deform under load. Microscope to show size of indent. |
| Industrial test for ductility/malleability | Bend test: how much plastic deformation prior to failure/cracks. Test piece into bending machine held, supported at ends. Mandrel/plunger loads test piece at centre and bends to predetermined angle or until fracture. Then inspected for cracks/defects |
| Diagram for izod impact test | Izod release position. Striker. Pendulum release lever. Test-piece clamping lever. Izod test piece. |
| Industrial test for ductility/malleability which side shows ductility/malleability | Inside of bend for malleability, outside for ductility |
| Non-destructive testing | Usually on products such as large castings with likelihood of internal defect or imperfection not detected by other methods. 2 standard types: ultrasonic and x-ray, although electrical/thermal conductivity do count. |
| Ultrasonic testing | Transducer generates sound waves pulsed into material. Intensity of reflected signal recorded on display unit - reflected at defects. All types of materials. Can be portable. High accuracy of flaw detection. Offshore and aerospace to check weld quality |
| X-ray testing | X-ray beam passes through material. image projected on display screen. X-rays, especially micro-focus x-rays. Give magnified images - minute flaws e.g. voids or hairline cracks to be reliably detected. |
| What is X-ray testing used for | Inspecting integrated circuits (ICs) and Printed Circuit Boards (PCBs), and to check for micro-voids in composite materials such as F1 cars. Also e.g. engine blocks for planes |
| Electrical conductivity in industry | A 4 probe method. 4 small-diameter wires stretched parallel to each other across non-conductive polymer block, held in place, and connected to copper terminal blocks. Lead to each wire. Outer leads given precise current and inner measure V drop. |
| Thermal conductivity in industry | Heat flow meter. Square test piece placed between 2 temperature controlled plates. Temp increased at controlled rate and heat flow measured by heat flow sensors on surface of material. As material heated to set temp, sensors measure conductivity |
Created by:
Pyrogearos2