Elastic Section Modulus
Relate a bending area moment to the extreme-fiber distance.
Try this formula
Calculate elastic section modulus or choose another supported quantity.
Show calculatorHide calculator
Try this formula
Calculate elastic section modulus or choose another supported quantity.
Use decimals or scientific notation, such as 1.2e3. Calculations update as you type.
Elastic section modulus
Enter the known values to see the result.
Use the area moment and extreme-fiber distance for the same bending axis. For an unsymmetric section, evaluate the two extreme-fiber distances separately. This is the elastic section modulus, not the plastic section modulus.
Difficulty
Intermediate
Read time
5 min
Prerequisites
Basic algebra, mechanics, and consistent SI units
Source
Donney Fan — MECH 360 — Mechanics of MaterialsReference equation: Bending — Section Modulus. FormuLab wrote new explanations, assumptions, applications, and numerical examples.
Definition
Section modulus combines the area distribution and the distance to a critical surface. A larger elastic section modulus reduces the extreme-fiber stress produced by a given bending moment.
Variables & Units
| Symbol | Meaning | Units |
|---|---|---|
| Elastic section modulus | ||
| Second moment of area about the bending axis | ||
| Distance from the neutral axis to the selected extreme fiber |
Real-World Applications
Beam sizing
Compare elastic bending resistance of candidate sections.
Stress estimation
Use σ = M/S at an extreme fiber.
Worked Example
Problem
A section has I = 0.000004 m⁴ and extreme-fiber distance 0.05 m. Find S.
Given
Solution
Final Answer
Contents
Info
Tools
Source & review
Reference equation: Bending — Section Modulus. FormuLab wrote new explanations, assumptions, applications, and numerical examples.
Assumptions
- • Use the area moment and extreme-fiber distance for the same bending axis.
- • For an unsymmetric section, evaluate the two extreme-fiber distances separately.
- • This is the elastic section modulus, not the plastic section modulus.
Languages
FormuLab is a study reference. Verify formulas, units, assumptions, and course-specific conventions before relying on them.