Material model

• Elasticity: Shape goes back toward its original rest position when external forces are removed.
• • -Purely elastic models don't loose energy when deformed (potential \(\leftrightarrow\) kinetic)

• Plasticity: Opposite of elasticity. Plastic material don't come back to their original shape (/change their rest position during deformation).
• • - Ductile material - can allow large amount of plastic deformation without breaking (plastic)
  • - Brittle - Opposite (glass, ceramics)

• Viscosity: Resistance to flow (usually for fluid, ex. honey)

In reality

• - Elasto-plastic materials: Allow elastic behavior for small deformation, and plastic at larger one.
• - Visco-elastic materials: Elastic properties with delay.