Metric and Imperial Units

The above formulas may be used with both imperial and metric units. As with all calculations care must be taken to keep consistent units throughout with examples of units which should be adopted listed below:

Notation

• σ_T = tensile Stress, psi or MPa
• A = area, in⁴ or mm⁴
• D = depth, in or mm
• D_F = final depth, in or mm
• E = modulus of elasticity, psi or MPa
• L = length under consideration, in or mm
• L_F = final length, in or mm
• P = pressure under consideration, psi or MPa
• v = Poisson's ratio, unitless
• ∆_D = change in depth, in or mm
• ∆_L = change in length, in or mm
• σ = stress, psi or MPa
• ε = strain, unitless

1. D. Roylance. Mechanical Properties of Materials. 2008. Print.
2. H.F. Boyer. Atlas of Stress-Strain Curves, ASM International. Metals Park, Ohio. 1987. Print.
3. M. Ashby. Materials: Engineering, Science, Processing and Design, Elsevier, Amsterdam. 2007. Print.
4. Raymond, J. (2015). Stress strain equations calculator: mechanics of materials - solid formulas. Retrieved from https://www.ajdesigner.com/phpstress/stress_strain_equation_strain_change_length.php