1. Technological World – CH 12 Manufacturing Technical Objects
Constraints and Deformations

2. Constraints
A constraint describes the effect of external forces acting on an object or material
We will discuss:
Compression
Tension
Torsion
Deflection
Shearing

3. Compression
A material subjected to forces that tend to crush it is undergoing compression
Symbol:
Examples:
Squeezing sponge
Crushing can
Press
Dribbling

4. Tension
A material subjected to forces that tend to stretch it is undergoing tension
Symbol:
Examples:
Suspended rope
Tug of war
Tow truck

5. Torsion
A material subjected to forces that tend to twist it is undergoing torsion
Symbol:
Examples:
Wringing a towel
Twisting an elastic
Twisting a flexible ruler
Chris Hadfield:

6. Deflection
A material subjected to force that tend to bend it is undergoing deflection
A force in the middle is being opposed by forces at the end
Symbol:
Examples:
Bow and arrow
Fish bending a rod
Clothes weighing down a clothesline

7. Shearing
A material subjected to forces that tend to cut it is undergoing shearing
Requires forces acting in opposite directions
Symbol:
Example:
Scissors cutting paper
Metal cutters trimming
Skating

8. Material Deformation
When a material or object is subjected to a constraint, one of three types of material deformation can occur:
Elastic
Plastic
Fracture

9. Elastic Deformation
A temporary change in the shape or dimensions of the material occurs. When the constraint (force) is removed, the material returns to its original form.
Example:
Elastic band
Bouncing ball

10. Plastic Deformation
A permanent change in the shape or dimensions of the material occurs. Even when the constraint is removed, the material remains deformed.
Example:
Soda can
Bent spoon

11. Fracture
The constraint is so intense that the material breaks