The Technological World Constraints Tension Compression And Torsion

The Technological World Constraints: Tension, Compression And Torsion

Constraints • Materials have to withstand several different forces and stresses. WHAT EXACTLY IS A CONSTRAINT? • The effect that an external force can have on a material. Can you think of any constraints that affect the way we build things?

Tension • Tension is a Reaction Force applied by a stretched string, rope, or other object on the objects which stretch it. • The direction of the force of tension is parallel to the string, away from the object exerting the stretching force.

• The amount of tension in the string determines whether it will break, as well as its vibration properties, which are used in musical instruments.

• The magnitude of the force of tension typically increases with the amount of stretching.

Examples of Tension

Compression • Compressive stress is the stress applied to materials resulting in their compaction (decrease of volume). • Usually, compressive stress applied to bars, columns, etc. leads to shortening.

Examples of Compression

• http: //dsc. discovery. com/videos/thedetonators-concrete-undertension. html

Torsion • In solid mechanics, torsion is the twisting of an object due to an applied torque.

Torsion Spring • The amount of force (actually torque) it exerts is proportional to the amount it is twisted. A torsion spring is often made from a wire, ribbon, or bar of metal or rubber, while more delicate ones are made of silk, glass, or quartz fibers.

• http: //science. discovery. com/videos/ behind-the-chunk/

Example of a Torsion Spring • A mouse trap is an excellent example of a torsion spring system.

Roadway of Tacoma Narrows Bridge twisting violently in a windstorm, Tacoma, Washington, 1940

Types of Deformation • Elastic : a temporary change in the shape and dimensions of an object • Plastic : a permanent change in the shape and dimensions of an object • Fracture : a permanent change that causes an object to break