This International Standard specifies a procedure for determining the in-plane shear stress/shear strain response, including the in-plane shear modulus and shear strength, of fibre-reinforced plastic composites by the ± 45° tension test method.

The method is suitable for use with thermoset and thermoplastic matrix laminates made from unidirectional layers and/or fabrics including unidirectional fabrics, with the fibres oriented at ± 45° to the specimen axis, where the lay-up is symmetrical and balanced about the specimen mid-plane.

As the test has been shown to be sensitive to the number and distribution of layers, comparisons should be undertaken using the same number of layers, which must be well distributed.