The flexural test using the aerospace standard DIN EN ISO 2746 is a 3-Point-flexural test for the characterization of flexural properties of unidirectional glass fibre reinforced composite thermosettings or thermoplasts (carbon fibre: see EN 2562). The test is conducted at constant speed until failure, while deformation as controlled by load is monitored. The required values are captured at determined deformation, maximum force and failure. The specimen’s geometry is rectangular and flat.

Three different modes of failure may occur: failure initiated at the surface by tensile stresses, failure initiated at the surface by the compression stresses, internal failure due to the shear stresses. For each specimen the mode of failure will be indicated.

The following properties may be determined using this method:

  • Flexural stress and deflection at failure of samples which break before or on reaching conventional deflection.
  • Flexural stress at conventional deflection of samples which break beyond conventional deflection.
  • Flexural strenght of samples which reach masimum load before or at conventional deflection.
  • Flexural strength or flexural stress at failure if this is required by the material standard.
  • Flexural modulus. Please note that the flexural modulus is only an approximate value of Young’s modulus of elasticity.