The tensile stress formula is extremely simple:

S = F / A

Where:

S: Tensile Stress (Megapascals [MPa])
F: Force (Newtons [N])
A: Cross-Sectional Area (square millimeters [mm²])

Once you have the Tensile Stress, you can then check up on your material's tensile yield stress (listed in materials datasheets) to see if it can withstand it with a sufficient safety factor.