Multiscale and Multidisciplinary Modeling, Experiments and Design https://doi.org/10.1007/s41939-019-00043-4 ORIGINAL PAPER Evaluation of a new green composite solution for wind turbine blades S. Boria 1 · C. Santulli 2 · E. Raponi 1 · F. Sarasini 3 · J. Tirillò 3 Received: 9 September 2018 / Accepted: 8 January 2019 © Springer Nature Switzerland AG 2019 Abstract The wind energy market requires reliable wind turbines with a long and efficient working life, able to generate energy without interruption, at the lowest investment and operating cost. The current material systems used for making wind turbine blades are in majority based on glass fibres and epoxy resins. These thermoset polymer composites with synthetic fibres have proved to be technologically mature and easy to work with during the manufacturing steps, with highly fluid resin that adheres well to the composites reinforcement fibres. However, glass fibre reinforced plastics show shortcomings, such as relatively high fibre density (approximately 40–50% higher than natural fibres), difficulty to be machined and limited recycling options, not to mention the potential health hazards posed by glass fibre particulates. Among its objectives, the SoftWind project should evaluate new green composite solutions that will lead to the design of recyclable and repairable blades with higher mechanical strength and lower weight than blades made of standard materials. Initially, to familiarise with natural fibres, specimens made of hemp fibres embedded in a vinylester matrix were tested in tension, flexure and impact, and compared with traditional glass fibres with different resins to validate their performance characteristics. Hemp fibres are good candidates for this use, since they offer a sufficient compatibility with technical matrices used in impact-resistant applications. This work validates on hemp/vinylester composite plates an analytical model previously introduced in the literature for synthetic composites when subjected to low-velocity/large-mass impacts. The validation is performed by comparison between the derived analytical load curves and the experimental ones. Moreover, in view of the final scope of modelling the behaviour of a full-scale blade under workloads, the obtained mechanical properties are also used to reproduce numerically, through a finite element code, the damage mechanisms of such bio-based composites. Keywords Wind turbine blade · Green composites · Hemp fibres · FEA 1 Introduction Nowadays, fossil fuel consumption is the major contribu- tor to the increasing concentration of greenhouse gases and climate change. The main solution strategy is represented by renewable energy sources and, among the others, wind power turned out to be very promising due to great quantity of renewable energy it is able to produce by occupying rea- sonably small and low-quality land sites. According to the B S. Boria simonetta.boria@unicam.it 1 Mathematics Division, School of Science and Technology, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy 2 School of Architecture and Design, University of Camerino, Ascoli Piceno, Italy 3 Department of Chemical Engineering Materials Environment, University of Rome “La Sapienza”, Rome, Italy EWEA (European Wind Energy Association) report Aim- ing High (EWEA Business Intelligence 2015), wind energy experienced a remarkable growth from the beginning of the twenty-first century, increasing the 12.9 GW of installed capacity in 2000, to the 128.8 GW of 2014, which corre- sponds to a total rise of nearly 900% over 14 years. One main drawback of wind energy, and of renewables in general, is represented by the prohibitive cost of energy (CoE), which is heavily influenced by the high-performance materials of the turbine structural components. Currently, available solutions are represented by wind turbine blades consisting of E-glass fibres in thermoset matrices (epoxy, polyester, vinylester) (Mishnaevsky et al. 2017). However, besides the cost disadvantage, glass fibre reinforced plas- tics are not easy to dispose of at the end of their life cycle. Therefore, to couple the many advantages of composite mate- rials with enhanced sustainability, vegetable fibres represent prospective substitutes to traditional composite reinforce- 123