A carregar...
Projeto de investigação
Associate Laboratory of Energy, Transports and Aeronautics
Financiador
Autores
Publicações
Experimental Evidence of Efficient Phononic-Based Vibration Isolators for Mechanical Applications
Publication . Policarpo, Hugo Filipe Diniz; Almeida, Raquel A.B.; Neves, Miguel M.; Maia, Nuno M.M.; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; MDPI - Multidisciplinary Digital Publishing Institute
Even though the design of vibration isolators is well-established for many engineering applications, their efficiency in wide and multiple frequency ranges is still a challenge. In these cases, the use of Phononic-Based Vibration Isolators (PBVIs) may be advantageous as they present different Attenuation Regions (ARs) in which the elastic waves are strongly attenuated. Therefore, the present paper is devoted to the experimental evaluation, in terms of force transmissibility, of different types of supporting devices tested on a load mass and a motor of a Hermetic Compressor (HC). Those devices are the original Helical Coil Spring (HS) that equips the HC, the PBVI, and the Combined Structure (CS) which is composed of a PBVI combined in series with the HS. Results evidentiate the capability of the CSs to isolate vibrations, where the PBVI contributes with its ARs, thus operating as a “filter” in specific frequency ranges, while the HSs maintain the flexibility of the CSs, which is advantageous for impact-loads and/or transient-case scenarios. Hence, the capability, relevance and impact that these PBVIs present for force transmissibility reduction applications is highlighted here, which should capture the attention of and motivate the industry, e.g., producers of isolation systems, since it has wide-ranging engineering applications.
Conceptual Design of an Unmanned Electrical Amphibious Vehicle for Ocean and Land Surveillance
Publication . Policarpo, Hugo; Lourenço, João P.B.; Anastácio, António M.; Parente, Rui; Rego, Francisco; Silvestre, Daniel; Afonso, Frederico; Maia, Nuno M.M.; CTS - Centro de Tecnologia e Sistemas; Faculdade de Ciências e Tecnologia (FCT); MDPI AG
Unmanned vehicles (UVs) have become increasingly important in various scenarios of civil and military operations. The present work aims at the conceptual design of a modular Amphibious Unmanned Ground Vehicle (A-UGV) that can be easily adapted for different types of land and/or water missions with low monetary cost (EUR < 5 k, without sensors). Basing the design on the needs highlighted in the 2021 review of the Strategic Directive of the Portuguese Navy, the necessary specifications and requirements are established for two mission scenarios. Then, a market research analysis focused on vehicles currently available and their technological advances is conducted to identify existing UV solutions and respective characteristics/capabilities of interest to the current work. To study and define the geometry of the hull and the configuration of the A-UGV itself, preliminary computational structural and fluid analyses are carried out to ensure it complies with the specifications initially established. As a result, one obtains a fully electric vehicle with approximate dimensions of 1050 × 670 × 450 mm (length–width–height), enabled with 6 × 6 traction capable of reaching 20 km/h on land, which possesses amphibious capabilities of independent propulsion in water up to 8 kts and an estimated autonomy of over 60 min.
Unidades organizacionais
Descrição
Palavras-chave
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDP/50022/2020