How this calculator works
Average normal stress is axial force divided by loaded area. Tensile force and extension are positive; compression is negative. Hooke modes assume uniform uniaxial linear elasticity. Engineering strain uses the original gauge length. Stress concentrations, bending and multiaxial loading require a local stress analysis rather than just average force divided by area.
Formula
sigma = F/A; epsilon = (Lf-L0)/L0; sigma = E epsilon in the linear elastic range.
Worked example
A 10 kN tensile force on 100 mm2 gives 100 MPa stress. For E = 200 GPa, a strain of 0.0005 gives the same stress.
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Frequently asked questions
What area should I use?
Engineering stress uses the original loaded area. True stress uses the current area.
Can force be negative?
Yes. Negative force represents compression with the sign convention used here.
Does Hooke's law apply after yielding?
Not as a single constant proportionality. Use a suitable material law beyond the elastic range.