What this tool does
Computes bending stress from the bending moment, distance from the neutral axis, and second moment of area, using σ = My/I for linear-elastic pure bending of a uniform section.
How to use it
- Enter the bending moment in N·m.
- Enter the distance from the neutral axis to the point of interest, in metres.
- Enter the second moment of area in m⁴.
- Run it for the stress in MPa.
Worked example
A moment of 1,000 N·m, a distance of 0.05 m, and I of 0.00001 m⁴ give a stress of 5 MPa.
Calculation method
Bending stress
moment*distance/inertia/1000000Frequently asked questions
- Where do I measure the distance from?
- From the neutral axis to the point you care about. For maximum stress, use the distance to the outermost fibre — half the depth for a symmetrical section.
- How do I get the second moment of area?
- Each section shape has its own formula; for a rectangle it is width × depth³ ÷ 12. Getting the unit to m⁴ matters a great deal.
What this tool does not cover
Linear-elastic pure bending only. Buckling, shear stress, plastic behaviour, torsion, stress concentration, and code checks are excluded. Do not use it alone to judge structural safety.