The Wonderful World of…
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Transcript of The Wonderful World of…
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The Wonderful World of…
TECHNOLOGY
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IN YOUR OPINION:
What IS technology?
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What is Technology?Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. (Wikipedia definition)
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What’s a Technical Object?
A man-made object that serves a purpose.
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Your Pencils
• Is it a technical object?
• Take a look at your pencils in your hands.
• What are the materials it is made of?
• How are materials decided for certain technical objects?
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MATERIALS
• External forces produce various effects inside a material.
EXAMPLE: *Consider what would happen if an elephant walked in the room and stepped on your pencil. What would the effect be?
EXTERNAL FORCE = Elephant weight
EFFECT = pencil being crushed
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Different materials react differently
to different external forces.
A material will undergo a mechanical constraint due
to the force.
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MECHANICAL CONSTRAINTS
“A mechanical constraint describes the stress produced within a material when it is subjected to external forces.”
5 types of constraints: Compression, Tension, Torsion, Bending, Shearing
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COMPRESSION: Force that crushes materials
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TENSION: Force that stretches materials
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TORSION:Force that twists materials
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BENDING:Force that bends materials
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SHEARING:Force that cuts or tears materials
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EXAMPLES:
• SHOES:
• CLICKER:
• WATER BOTTLE:
Tension, bending
Compression
Torsion, bending, compression
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What happens when there is TOO MUCH STRESS (constraint) on material?
• Elastic deformation – Temporary deformation of material. Resumes shape.
• Plastic deformation – Remains deformed.
• Fracture – Material ruptures.
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Your Pencils (again)
Have you ever asked yourself why pencils are never made out of rubber? Or out of glass?
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MECHANICAL PROPERTIES
• Determines how a material will react when it is subjected to one (or more) mechanical constraints.
• Examples of properties: Hardness, elasticity, ductility, malleability, tensile strength
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HARDNESSResists penetration
Reacts to pressure force by elastic deformation
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ELASTICITYRegains initial shape
Reacts to force by elastic deformation
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RESILIENCEResists physical impacts
Reacts to temporary force by elastic deformation.
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http://www.youtube.com/watch?v=j87UWgvetRg
Building Design Pulls Structure Upright after Earthquake
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Rumplestiltskin
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DUCTILITYStretches without breaking
Reacts to tension force by plastic deformation.
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MALLEABILITYFlattens or bends without breaking
Reacts to bending or compression force by plastic deformation.
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TENSILE STRENGTHResists tension without becoming permanently deformed
Reacts to tension force by elastic deformation
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SUMMARY: PropertiesHARDNESS Resists penetrationELASTICITY Regains initial shapeRESILIENCE Resists physical impactsDUCTILITY Stretches w/o breakingMALLEABILITY Flattens/bends without
breakingTENSILE STRENGTH
Resists tension without permanently deforming