Calculate flexural modulus from three-point bending test data or stress and strain, plus optional flexural strength and strain, in MPa, GPa, ksi or psi.

Simply supported rectangular specimen with a central load.

Examples fill span, width and thickness; verify the actual specimen and test requirements.

Flexural strength and strain (optional)
Optional. Peak load at break or yield; adds flexural strength ฯƒ = 3FL / (2bdยฒ).

Optional. Adds flexural strain ฮต = 6Dd / Lยฒ at that deflection.

Flexural Modulus Formula

The following ratio gives the origin-to-point flexural secant modulus. It equals the elastic modulus for appropriately zeroed linear-elastic data:

E = (ฯƒ) / (ฮต)

Variables:

  • E is the flexural modulus (MPa)
  • ฯƒ is the stress (MPa)
  • ฮต is the strain (unitless)

Divide corresponding flexural stress by strain to calculate the secant modulus. Tangent or chord modulus requires the appropriate stressโ€“strain slope.

What is Flexural Modulus?

Flexural modulus, also known as the modulus of elasticity in bending, is a measure of a material’s stiffness or resistance to flexural deformation. It is defined as the ratio of stress to strain in flexural deformation, or the tendency for a material to resist bending. It is an important parameter in engineering and materials science, particularly in the design and analysis of materials that will undergo bending stresses.

How to Calculate Flexural Modulus?

The following steps outline how to calculate the Flexural Modulus:


  1. First, determine the stress (ฯƒ) in the material under flexural load, measured in megapascals (MPa).
  2. Next, determine the strain (ฮต) in the material, which is a unitless value representing the deformation per unit length.
  3. Use the formula E = ฯƒ / ฮต to calculate the Flexural Modulus (E).
  4. Finally, enter the values of stress and strain into the calculator to find the Flexural Modulus.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Stress (ฯƒ) = 120 MPa

Strain (ฮต) = 0.005 (unitless)