Ultimate Strength of Quasi-Isotropic Composites: ISO 12215-5:2019 Validation

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Jean-Baptiste Souppez
Julio Laci


Glass fibre reinforced polymer composites are the most common materials employed for the manufacturing of small crafts, with the scantlings governed by ISO 12215-5:2019. However, no validation data is available to ascertain the relevance of the default ultimate strengths provided by the standard. This paper experimentally characterises the ultimate flexural, tensile and compressive strength of hand laminated and vacuumed bagged quasi-isotropic glass-epoxy laminate. The results show that ISO 12215-5:2019 default ultimate strengths for the quasi-isotropic composite laminate tested are (i) conservative for the ultimate flexural strength, (ii) appropriate for the ultimate tensile strength, and (iii) optimistic for the ultimate compressive strength, especially for vacuum bagged samples, with the main cause identified as the value of the ultimate compressive breaking strain for chopped strand mat. These findings provide validation data for ISO12215-5:2019 and it is anticipated the results may contribute to future improvements in small craft regulations.

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Author Biography

Jean-Baptiste Souppez, Aston University, UK

Jean-Baptiste R. G. Souppez is the Senior Teaching Fellow in Mechanical Engineering and Design, and the Learning Enhancer for Mechanical Engineering, Biomedical Engineering and Design, at Aston University, as well as a Senior Fellow of the Higher Education Academy, and a Research Inspired Teaching Excellence (RITE) mentor. His teaching focuses on Engineering Materials, CAD Principles & Material Selection, and CDIO modules, namely Prototyping & Development and Engineering for Industry. He is also the Deputy Editor-in-Chief of the Society of Naval Architects & Marine Engineers (SNAME) Journal of Sailing Technology, the world's leading peer-reviewed journal for sailing research, and sits on several prestigious and influential international committees. His work in fluid dynamics features a wide range of experimental methods, supporting his cutting-edge expertise in hydrofoils and award-winning research on the aerodynamics of downwind racing yacht sails. As the UK Principal Expert in Small Craft Structures, he is in charge of representing the interests of the British Marine Industry in the development of international structural regulations (ISO 12215) thanks to his extensive knowledge of composites and structural design and analysis. Recognised as an international leader in yacht design, he also oversees all small craft regulatory developments on behalf of the Institute of Marine Science, Engineering and Technology (IMarEST) in his capacity of Liaison on the UK Small Craft Committee. He promotes professional development as an Associate Tutor in Engineering for Marine Professionals at the MLA College, part of the University of Plymouth, supervising post-graduate researchers and enabling established professionals to achieve Chartered Engineer (CEng) status through the IMarEST. Furthermore, he contributes to the highly international Erasmus Mundus Master in Advanced Design in Ship and Offshore Structures (EMship+) as a Visiting Professor and Research Supervisor at the University of Liege.