• Test method for orthotropic FRP (GFK, CFK, ...) for determining the thrust properties (thrust properties within the layer plane)
• Specimen geometry 250 mm x 25 mm x 2.5 mm with fiber orientation in +/-45° direction
• Application of an adapted DMS rosette in 0°/90° orientation
• Determination of shear strength, shear stiffness and shear stress-strain curve

In accordance with ASTM D3518 (or DIN EN ISO 14129) shear characteristics are determined in the so-called tensile shear test on flat test specimens with a fiber orientation in a +/-45 ° direction. The test specimen is ideally symmetrical and balanced from its laminate construction and consists of a fabric or a biaxial scrim. The characteristic value determination is carried out quasi-statically as a tensile test. The test method has the following disadvantages compared to other methods:

• The test is not applicable to the determination of fracture toughness for materials with high shear strain, as the process is limited to shear deformations < 5 %.
• The resulting stress state in the test specimen is multiaxial. In the single layer of the specimen both normal and shear stresses are present. The fiber-perpendicular stresses generate additional ZFB stress in the laminate and thus an influence on the shear characteristics. The determination of the shear strength according to ASTM D3518 is therefore not possible error-free due to the principle.
• The free (not clamped) edges of the specimen lead to load transfer effects.
• It is assumed that the load is inhomogeneous over the width of the specimen.

The advantage of the test method over other methods for determining shear rate value lies in the simplicity of the test procedure. It is essentially a tensile test which has been modified by the fiber orientation in the +/-45° direction for the determination of the shear characteristics.