Statics and strength

Calculate beam deflection

Determine reactions, shear, bending moment, stress, and maximum deflection for four basic load cases.

wmaxSI
01

Beam model

02

Results

ƒ(x)

Set the inputs and run the calculation.

Inputs and method

Beam deflection using Euler-Bernoulli theory

Calculate reactions, moment, stress and deflection for basic beam load cases.

Inputs

Length, load and position, Young's modulus E, second moment I and section modulus W describe beam and load.

E describes material stiffness, I section distribution and L load leverage. Deflection therefore grows strongly with L and falls strongly with I; adequate strength alone does not guarantee stiffness.

Calculation

Euler-Bernoulli EI·w″ = M(x) links moment to curvature; boundary conditions determine deflection.

Example

Doubling I approximately halves deflection for the same load case.

Sources and limits: Classical small-deflection, linear-elastic beam theory; shear deformation and self-weight are excluded.

Load cases

Supports, load and deflection

Four basic cases show how support and loading determine deflection. θmax is intentionally omitted.

Simply supported · point load

FLyₘₐₓ

Simply supported · distributed load

wLyₘₐₓ

Cantilever · end load (free end)

FLyₘₐₓ

Cantilever · distributed load

wLyₘₐₓ
Original schematic illustration · not to scale
Purpose

What the calculator is for

Length, load, elastic modulus, I, and W describe a prismatic beam. Typical applications include early stiffness estimates for beams, brackets, and machine frames.

Limits

What still needs checking

Euler-Bernoulli theory assumes small deformation, linear-elastic material, and a slender beam. Shear deformation, self-weight, and stability failure are excluded.