The Wonderful World of…

TECHNOLOGY

IN YOUR OPINION:

What IS technology?

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)

What’s a Technical Object?

A man-made object that serves a purpose.

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?

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

Different materials react differently

to different external forces.

A material will undergo a mechanical constraint due

to the force.

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

COMPRESSION: Force that crushes materials

TENSION: Force that stretches materials

TORSION:Force that twists materials

BENDING:Force that bends materials

SHEARING:Force that cuts or tears materials

EXAMPLES:

• SHOES:

• CLICKER:

• WATER BOTTLE:

Tension, bending

Compression

Torsion, bending, compression

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.

Your Pencils (again)

Have you ever asked yourself why pencils are never made out of rubber? Or out of glass?

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

HARDNESSResists penetration

Reacts to pressure force by elastic deformation

ELASTICITYRegains initial shape

Reacts to force by elastic deformation

RESILIENCEResists physical impacts

Reacts to temporary force by elastic deformation.

http://www.youtube.com/watch?v=j87UWgvetRg

Building Design Pulls Structure Upright after Earthquake

Rumplestiltskin

DUCTILITYStretches without breaking

Reacts to tension force by plastic deformation.

MALLEABILITYFlattens or bends without breaking

Reacts to bending or compression force by plastic deformation.

TENSILE STRENGTHResists tension without becoming permanently deformed

Reacts to tension force by elastic deformation

SUMMARY: PropertiesHARDNESS Resists penetrationELASTICITY Regains initial shapeRESILIENCE Resists physical impactsDUCTILITY Stretches w/o breakingMALLEABILITY Flattens/bends without

breakingTENSILE STRENGTH

Resists tension without permanently deforming