Materials

Materials:

1. Static effect of a force on a body    Stress is force per unit area (pressure) Absolute deformation    Percent deformation (strain)

2. Tensile force is a stretching force.    Tensile force causes extension.   Tension is the response force accordingly to the Newton`s 3rd law. A tensile force creates a tensile stress. Loosely speaking if a tensile force is applied a body is under tension.

3. Compressive force is contracting/shrinking  force.    Compressive force causes compression. A body under compressive force will fight back by...    Tension  must not be used for compressive forces 

4. Shear force    Bending force

5. Stress-strain curve (force-extension graph)

   • Elastic region (deformation is reversible)

     • 1. Proportionality region    and    Hooks Law 

       2. Young modulus 

       3. Stiffness constant

   • Elastic limit

   • Yield point

   • Plastic region - deformation is permanent  ( dashed line is representing the unloading curve ) 

     • 1. If plastic region between Yield point(dashed line is almost vertical) the breaking point is big then the material is Malleable (easy to deform under hammering) and also  Ductile (easy  to deform under pressure)  

       2. Brittleness - very small plastic region before braking

Hardness is ability not to deform or how difficult is to make permanent surface deformation (indentation or scratch) (In a sloppy way  height of elastic limit)

5. • • 3. Toughness is ability to absorb energy (area of stress-strain curve)

   • Braking stress (UTS)