The Spanish Association for Standardisation (UNE) has published the UNE 0074:2023 Specification, aimed at the aeronautical, aerospace, automotive, naval and other industries, which is based on a methodology developed by our COMES research group. The purpose of this specification is to obtain a more precise knowledge of the shear response of continuous fibre reinforced polymers (FRP), a type of material with great potential for the construction of lightweight structures due to its high stiffness and strength.
Specification UNE 0074:2023, entitled “Tensile compression shear test method on cruciform specimen”, has been developed by UNE through the Technical Committee for Standardisation 53, dedicated to Plastics and Rubber (CNT 53), in Working Group 8 (WG8) under the secretariat of the Spanish Association of Plastics Industrialists (ANAIP). In addition to the Group of Mechanics of Continuous Media, Structures and Materials Engineering (COMES) of the UCLM, the Instituto Tecnológico del Plástico (AIMPLAS), the Instituto de Ciencias de la Construcción Eduardo Torroja and the company Siemens-Gamesa have collaborated in its drafting.
The paper describes the method to determine the mechanical shear response of reinforced and unreinforced plastics, based on the research carried out by the COMES research group in the COMMUL and BISHEAR projects, developed within the framework of the 2016 State Programme for R&D&I Oriented to the Challenges of Society and the 2021 Proof of Concept Projects.
In industries such as aeronautics, aerospace, automotive, naval, as well as in wind turbines and technologies related to medicine or sports, ‘the need to reduce weight is crucial to improve the performance of various structural parts’. FRPs are materials with great potential for the construction of lightweight structures due to their high stiffness and strength. Although there are previous standardised tests that are “adequate” for characterising shear stiffness, “they can lead to very different estimates of shear strength”.
The method developed by the UCLM makes it possible to evaluate the mechanical behaviour of FRP materials subjected to pure shear for the design of lightweight structures, by means of a biaxial tensile-compression test on cruciform specimens, which makes it possible to observe the response up to deformation values higher than those achieved in the most commonly used standardised tests.
‘The creation of the UNE 0074:2023 Specification advances towards a more precise knowledge of the response of FRP materials in the structural design stages, allowing the weight of components to be reduced by minimising their oversizing,’ they explain. This specification has applications in the transport sector (land, sea, air and space), where lighter vehicles would contribute to reducing fossil fuel consumption and thus CO2 emissions. Also in the wind industry, as the reduction of the weight of the blades would improve their efficiency in the current trend of increasing their size to obtain more energy from the wind.
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