Additive manufacturing (AM) of polymer large parts is a technological research area with great growth potential if the main barriers to its implementation are successfully addressed. In this research, a review of large-format AM (LFAM) processes for polymers is presented, followed by market research concerning the identification of large-format polymer commercial printers. An overview was performed covering the current LFAM systems configurations and their control aspects. The design and modelling approaches related with the fabrication of polymer large parts by AM, and the materials currently being applied and under development, were described. Finally, a summary of LFAM applications with a focus in the Transportation, Academic, Construction and Energy sectors, was presented. The current main advances in the LFAM of polymers are linked with the possibility of producing large parts in a faster, cheaper, and reliable way. The market research analysis concerning results for all AM families involving polymer materials reveals that, currently, the material extrusion AM process family is potentially the most suitable to produce large parts, with a significant number of applications attesting its capability to produce such large-format components.
24 January 2020 in Material Design & Processing Communications
The interest in airless or non-pneumatic tire (NPT) structures emerges due to potential performance and environmental advantages, such as reduced rolling resistance and improved recyclability, when compared with traditional rubber-based pneumatic tires. NPTs can already be found in commercial applications such as forklifts, electric scooters, and wheelchairs. Even so, up to the knowledge of authors, there is no known established large-scale production of NPTs for most applications. This work presents a systematic literature review regarding the mechanical design and development of NPTs. A summary of structural characteristics and mechanical behaviour analysis is provided. Relevant standards, analysis strategies, materials, production techniques, and the end-of-life of tires are addressed. In the end, the authors debate the current challenges and prospects of these emergent products. Furthermore, this research aims at being used as a tool, potentiating the development of innovative and efficient, airless tire solutions. The review presented clarifies that many academic efforts are focused on finding optimal functional designs, which are frequently complex and physically demanding. These geometrically complex design proposals are, in most cases, composed of intricate cellular structures and spokes arrangements. Based on the current lack of knowledge, authors identify key research areas to be further developed such as the production, performance, and reliability of NPTs. It is debatable whether there will ever be a shortcoming of the rubber tire, or a time when fully recyclable tires are a societal obligation. Nevertheless, the number of reasons to promote the development of a reliable replacement to the traditional tire is far from scarce.