Formulas for Calculating Stress at a Point
When dealing with mechanics of materials, choosing the correct formula to calculate the stress at a given point can be difficult. Normal and shear stresses come in a wide variety of applications, each stress application with its own calculation formula. The most common stress types you deal with in basic mechanics of materials fall into several major categories:

Axial tension: A_{NET} is equal to the gross area of the cross section minus any holes that may exist.

Thinwalled pressure vessels: Two stresses exist: an axial stress along the axis of the member and a hoop (or radial) stress, which occurs tangential to the radius of the cross section. These stresses are based on the gage pressure p inside the pressure vessel.
For cylindrical pressure vessels, use this pair of formulas:
For spherical pressure vessels, use the following formula:

Bending stresses: For symmetric cross sections in the XY plane, use this formula:
(moment about the xaxis)(moment about the yaxis)

Flexural shear stresses: Here’s the formula for calculating flexural shear stress:

Torsional shear stress: Use this formula to find torsional shear stress: