1. Write down the equation of equilibrium in the absence of body forces. Use index notation.
  2. Write down the relationship between the traction vector acting on an arbitrary surface of a body and the stress tensor in the body.
  3. Write down the basis transformation rule for the stress tensor in both index notation and matrix notation.
  4. Consider a square block under pure shear as shown below. Draw the directions of the maximum and minimum principal stresses on the figure. Ignore the third dimension.
Pure shear.