Bend Test

Since bending load usually occurs, it is very important for determining the characteristic values for polymers and fibre-reinforced composites. For this test, stiff samples are inevitable. The tested materials are part of the polymer classes of thermoplastics, thermosetting plastics, laminates or fibre-reinforced polymers. The characteristic parameters like flexural modulus Ef and flexural strength σfM can be determined by a three-point or four-point bend test.

Specimen Preparation

  • Injection moulding
  • Sawing
  • Milling

Testing Conditions

  • Testing speed up to 1250 mm/min
  • Temperature control for the three-point bend test from -50 °C to 250 °C
  • Temperature control for the four-point bend test from -40 °C to 100 °C
  • Climate control: standard atmosphere (23 °C, 50 % relative humidity)
  • Force ranging from 5 N to 100 kN
  • Support span up to 250 mm
  • Radius of the bending punch and the supports from 2 mm to 12.5 mm
  • Testing of stiff samples, e.g. of thermoplastics, duromers, thermosetting plastics, laminates and composites
  • Investigations of samples with different dimensions (thickness, width and length)
    (The sample dimension depends on the sample thickness and the material class (I–IV).)

Accredited Standards

  • DIN EN 2562:
    Aerospace series – Carbon fibre reinforced plastics – Unidirectional laminates; Flexural test parallel to the fibre direction
  • DIN EN ISO 178:
    Plastics – Determination of flexural properties
  • DIN EN ISO 14125:
    Fibre-reinforced plastic composites – Determination of flexural properties 

Other Standards

  • ASTM D 790:
    Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulation Materials
  • ISO 1209-1
    Rigid cellular plastics – Determination of flexural properties – Part 1: Basic bending test
  • ISO 1209-2
    Rigid cellular plastics – Determination of flexural properties – Part 2: Determination of flexural strength and apparent flexural modulus of elasticity

Do you prefer testing according to another standard? Do you prefer testing according to a company standard or a standard which is not mentioned here? Do you need some scientific investigations for using our equipment?

Please do not hesitate to contact us. We check for you if we can realise the requirements of your standards with our equipment and fixtures. In addition, we advise you on testing non-standard construction components or samples.  


Dipl.-Wirtsch.-Ing. Stephan Arndt
Telefon: +49 (0)3461 30889-68

Dipl.-Ing. Heidrun Müller
Telefon: +49 (0)3461 30889-68



  • Flexural modulus Ef
  • Bending strength σfM
  • Bending stress by conventional bending (Standard bending stress) σfc
  • Bending stress during fracture σB
  • Bending at bending strenghth εfM
  • Interlaminar shear modulus G
  • Bending strength–bending elongation–curve

Test Arrangements

  • Three-point bending test
  • Four-point bending test
  • Procedure A
  • Procedure B


  • ASTM D 790
  • DIN EN ISO 178
  • DIN EN ISO 14125
  • ISO 1209-1
  • ISO 1209-2