Fibre-reinforced plastic composites — Determination of the in-plane shear modulus by the plate twist method.
The Standard specifies a method for determining the flat shear modulus (G12) of fiber reinforced plastic composites using a standard plate sample. When applied to isotropic materials, the measured shear modulus is independent of the direction.
The method is used to determine the shear modulus of the test samples, but not to determine the shear strength. It is applied to a plate resting on two points on a diagonal and loaded on the other diagonal by the simultaneous movement of two load points attached to a transverse beam.
The method is suitable for use with fiber reinforced plastic composite materials with thermoplastic and thermoplastic matrices.
Because the shear strain is applied under bending conditions, for laminated materials with different fiber formats and / or different orientations, the layers of material must be well distributed across the section so that they are approximately “homogeneous” in the thickness direction.
The main axes of the material, if any, should be oriented perpendicular to the edges of the plate.
NOTE This method can be applied to non-reinforced polymers and other materials (for example, metals, ceramics and composites of metallic matrix or ceramic).
For the material fabricated using unidirectional layers, the shear modulus obtained using a multidirectional specimen (ie, 0 ° / 90 ° / ± 45 °) is not the same as that obtained for the unidirectional or crossover material (0 ° / 90 °).