Abstract

The biaxial tension-compression test with a cruciform specimen on symmetrical angle-ply ±45º laminates is proposed as an alternative that improves the results of existing methodologies to determine the pure shear properties in principal material directions. The method satisfies the main requirements for shear tests: i) it concentrates uniform stresses and strains in the biaxially loaded area, from which the shear response can be extracted; ii) it is possible to observe the linear and non-linear stress-strain evolution up to failure levels higher than those of traditional tests; iii) the failure is triggered in the biaxially loaded region, what allows calculating not only the shear stiffness during the linear stage, but also the shear strength. In addition, in carbon fibre reinforced polymeric matrix laminates, it is possible to increase up to 40% the level of shear strain at the moment of failure using a biaxial anti-buckling accessory that prevents the appearance of instabilities in the arms of the specimen. In this work, the test methodology recommended in Specification UNE 0074:2023, prepared by the Technical Committee CTN 53/GT 8, is shown. The specification is based on the previous research carried out in the COMMUL and BISHEAR projects developed within the framework of the national programs of R&D&I programme oriented towards the challenges facing society 2016 and the "Proof of Concept" projects 2021.