Eco-Friendly Cork-Polyurethane Biocomposites for Enhanced Impact Performance: Experimental and Numerical Analysis.

Cork composites are byproducts from wine stopper production, resulting from the agglomeration of cork granules with a thermoset resin. The resulting compound is a versatile and durable material with numerous industrial applications. Due to its unique properties, such as low-density, high-strength, excellent energy absorption, and good thermal and acoustic insulators, cork composites find room for application in demanding industries such as automotive, construction, and aerospace. However, agglomerated cork typically has a polyurethane matrix derived from petrochemical sources. This study focuses on developing eco-friendly porous polyurethane biocomposites manufactured with the used cooking oil polyol modified with cork. Since cork and polyurethane foam are typically used for impact shock absorption, the manufactured samples were subjected to impact loading. The assessment of crashworthiness is performed through 100 J impact tests. A finite element numerical model was developed to simulate the compression of these new composites under impact, and the model validation was performed. The highest specific absorbed energy was obtained for petrochemical polyol composites with the 3% addition of natural or modified cork. The research conducted in this study showcased the feasibility of substituting certain petrochemical components used for the synthesis of the polyurethane matrix with ecological waste vegetable oil components.

Shear thickening fluid (STF) in engineering applications and the potential of cork in STF-based composites.

Shear thickening fluids (STFs) are a unique type of fluids that can quickly transform into a solid-like state when subjected to forces (rate dependent). These fluids are created by dispersing micro and nanoparticles within a medium. When the force is removed, they return to their original liquid state. Shear thickening fluids can absorb a significant amount of impact energy, making them useful for reducing vibrations and serving as a damper. This study provides a comprehensive and brief overview of existing literature on shear thickening fluids, including their properties, classification, and the rheological mechanisms behind the shear thickening behaviour. It also examines the use of these fluids in various applications, such as improving resistance to stabs and spikes, protecting against low- and high-velocity impacts, and as a new medium for energy dissipation in industries such as battery safety, vibration control and adaptive structures. Lastly, this work reviews the promising combination of STFs with cork. Given the sustainability of cork and its energy absorption capacity, cork-STF composites are a promising solution for various impact-absorbing applications. Overall, the paper underscores the versatility and potential of STFs, and advocates for further research and exploration.

Head protection in electric micromobility: A critical review, recommendations, and future trends.

Traffic jams are a burden in urban areas, being time-consuming and contributing to stressful driving and CO2 emissions. To implement the United Nations' 2030 agenda for sustainable development, governmental strategies aim to accelerate the shift to sustainable and smart mobility. Consequently, e-micromobility (EMM) appeared as a practical solution for short-distance commuters, and it is growing at upsetting rates thanks to the introduction of sharing services. In fact, urban mobility has drastically changed over the last decade, and electric mobility and micromobility changed the panorama in larger metropolises, given their accessibility, large availability, and the potential to be a time saver in short trips and a potentially sustainable alternative in particular scenarios. The downside of portable e-transportation is the rapid increase in injuries and fatalities. Focusing on standing e-scooters, head injuries are becoming one of the most common as shown by research conducted in different urban emergency departments, alongside bone fractures, skin abrasions, and lacerations. In this work, a comprehensive review is carried out focusing on head protection for EMM, mostly for e-scooters, and the respective target markets, safety measures, and existing regulations. In the end, a critical assessment is given with recommendations for legislators and future research. Users are mostly males from 18 to 40 years old, upper-to-middle income, with elevated levels of educational attainment. Their motivation to use e-scooters is mainly to replace short walking trips. EMM, in particular e-scooters, will continue to grow thanks to its potential to substitute other micromobility alternatives. The evolution of safety measures and regulations did not keep pace with such a drastic change in mobility trends. This is evident considering how some countries are struggling with vehicle categories and regulations for helmet use and testing. The lack of legal obligation to wear a helmet and the absence of an adequate and feasible concept of protective equipment for sharing services are the main barriers to helmet use among riders. Mitigation measures have been implemented by the EMM sharing companies to improve the safety of its users by checking if they wear helmets and by offering vehicle-integrated solutions.