KEVOS® MAKEOS · Engineering
Section Properties
What area and bending properties follow from this section?
Calculate area, centroidal second moments, elastic section moduli and radii of gyration for four ideal section shapes.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Ideal section shape | choice | Select the ideal geometry; commercial sections can have corner radii and tolerances. |
| Width or outside diameter | mm | Outside horizontal width for rectangles or outside diameter for circles. |
| Outside height (rectangles only) | mm | Outside vertical height; ignored for circles. Leave a valid positive value when unused. |
| Wall thickness (tubes only) | mm | Uniform wall; ignored for solid sections. Leave a valid positive value when unused. |
Method and formulas
- Rectangle: A = bh, Iₓ = bh³/12, Iᵧ = hb³/12. Circle: A = πD²/4, Iₓ = Iᵧ = πD⁴/64.
- For tubes subtract the centred inner shape. Section modulus Z = I divided by the corresponding extreme-fibre distance; gyration radius = √(I/A).
- Example: a 40 × 80 mm rectangle gives A = 3200 mm², Iₓ = 1,706,666.667 mm⁴, Iᵧ = 426,666.667 mm⁴ and Zₓ = 42,666.667 mm³.
Limitations
- Hollow rectangles have sharp corners. Use certified catalogue or CAD properties for rounded stock.
- Area second moments are not mass moments. Iₓ + Iᵧ is not the torsion constant of a rectangle.
- No stress, allowable load, buckling resistance or structural-code compliance is determined.
- Default values are worked examples, not recommended settings or material properties.
Typical uses
- second moment of area
- section modulus
- rectangular tube
Who it is for
- Mechanical designers
- CAD users
- Fabricators
What you get
- Area and centroid from lower-left bounding corner
- Centroidal horizontal Iₓ and vertical Iᵧ
- Elastic section moduli and gyration radii
Interpreting the result
- Match the bending axis when transferring I or Z to another calculation.
- Centroid coordinates use the lower-left outside bounding corner; moments are about centroidal axes.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 236–244. Topic reference; implementation and examples are original, and no source tables are reproduced.
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