Apparent Inter-laminar Shear Strength

The apparent inter-laminar shear strength τM (ILSF or ILSS, inter-laminar shear strength) can be determined from fibre-reinforced polymers with thermoplastic or thermosetting matrices, provided that during the test a fracture of the specimen is caused by inter-laminar shear. For this purpose, a specimen is loaded in a three-point bending arrangement, whereas an increase in the shear stress and inter-laminar failure is to be realised by a suitable choice of the ratio of specimen thickness to the support span. After the fracture of the specimen, the fracture surface is evaluated and the type of failure determined (shear failure, mixing failure of train, shear and pressure, non-shear-related failure or shear).

Specimen Preparation

  • Sawing
  • Milling

Testing Conditions

  • Three-point bending equipment
  • Temperature control for the three-point bend test from -50 °C to 250 °C
  • Climate control: standard atmosphere (23 °C, 50 % relative humidity)   

Accredited Standards

  • DIN EN ISO 14130:
    Fibre reinforced plastic composites – Determination of apparent interlaminar shear strength by short beam-method

Other Standards

  • DIN EN 2377:
    Aerospace series – Glass fibre reinforced plastics – Test method – Determination of apparent interlaminar shear strength
  • DIN EN 2563:
    Aerospace series – Carbon fibre reinforced plastics – Unidirectional laminates – Flexural test parallel to the fibre direction


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

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



  • Apparent inter-laminar shear strength τM
  • Shear failure
  • Failure types:
    • Shear fracture
    • Mixed failure consisting of tension, shear and pressure
    • Not-shear-related failure
    • Shear


  • DIN EN 2377
  • DIN EN 2563
  • DIN EN ISO 14130

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