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)
Whats 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.
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
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
Resists penetration Reacts to pressure force by elastic deformation