In this work, unidirectional carbon-fiber-reinforced polymers (CFRP) with embedded NiTi shape memory alloy (SMA) wire actuators were manufactured using a universal testing machine equipped with a thermally controlled chamber. Beam specimens containing cold-worked, annealed and trained NiTi SMA wires distributed along their neutral plane were fabricated. Several tests in a three-point bending mode at different constant temperatures were performed. To verify thermal buckling effects, electrical activation of the specimens was realized in a cantilevered beam mode and the influence of the SMA wire actuators on the tip deflection of the composite is demonstrated.

No abstract

No abstract

No abstract

Mechanical vibrations are severe phenomena of the physical world. ese oscillations may become undesirable and may cause temporary and even irreversible damage to the system. ere are several techniques to minimizing these vibration effects ranging from passive methods to the use of controllers with smart materials. In this sense, this study aims to analyze a passive vibration control system installed in a structure that simulates two-floor buildings. is system based on the incorporation of one SMA-SE (Superelastic Shape Memory Alloys) coil springs configuration for energy dissipation and the addition of damping. Modal analysis was performed using analytical, numerical, and experimental methods. In an experimental basis, response amplitudes were analyzed for free and forced vibrations in different configurations. As compared with the structure configuration with steel spring, the forced vibrations FRF (Frequency Response Function) analysis showed a reduction in displacement transmissibility of up to 51% for the first modal shape and 73% for the second mode in the SMA-SE coil spring configuration. As for damping, there was a considerable increase in the order of 59% in the first mode and 119% in the second, for the SMA-SE springs configuration.

This work presents an experimental study related to the mechanical performance of a special design spring fabricated with a superelastic shape memory alloy (SMA-SE). For the experimental testing, the spring was coupled in a rotor machine, aiming to attenuate the mechanical vibration when the system went through a natural frequency without any external power source. It was verified that the reduction in instabilities stemmed from the better distribution of vibration force in the proposed device, as well as the damping capacity of the spring material. These findings showed that the application of the M-Shape device of SMA-SE for three different cases could reduce vibration up to 23 dB when compared to the situations without, and with, 1.5 mm of preload. The M-Shape device was shown to be efficient in reducing the mechanical vibration in a rotor system. This was due to the damping capacity of the SMA-SE material, and because the application did not require any external source of energy to generate phase transformation.

Este livro reúne uma seleção dos trabalhos apresentados no III Simpósio de Pós-Graduação em Engenharia Mecânica (SiPGEM), que teve como tema: "Empreendedorismo e Inovação na Pesquisa", sendo realizado na Universidade Federal de Campina Grande, em Campina Grande, Brasil, de 2 a 4 de outubro de 2019. O simpósio surgiu em 2017, por inciativa dos alunos de mestrado do Programa de Pós Graduação em Engenharia Mecânica, buscando melhorar e divulgar o programa. Assim, criou-se um evento científico local e regional, para a comunicação e divulgação da comunidade acadêmica, onde pesquisadores, pósgraduandos e graduandos são incentivados a expor seus trabalhos, palestrar e debater suas ideias. Nesta edição do evento, os trabalhos foram publicados no formato de resumo expandido, a fim de permitir que uma maior amostra do acervo científico apresentado no evento integrasse o livro. A comissão científica avaliou e selecionou ao todo vinte e dois trabalhos para compor este livro, no qual os tópicos abordados estão relacionados às principais linhas de pesquisa desenvolvidas no programa de pós-graduação em Engenharia Mecânica da UFCG: Análise e Projeto de Sistemas Termomecânicos (AST), Fenômenos de Transporte e Energia (FTE), Processos Mecânico-Metalúrgicos (PMM). Acreditamos que os vinte e dois capítulos oferecem uma boa amostra das pesquisas desenvolvidas nessas áreas dentro da nossa comunidade acadêmica local, sendo uma valorosa fonte de informações técnicas, bem como inspiração para futuras pesquisas. Por fim, agradecemos a todos que contribuíram com seus trabalhos para composição desse livro, à UAEM/UFCG, a Editora Poisson pela parceria que tornou este trabalho possível, as agências de fomento as pesquisas (CNPq, CAPES, Fapesq-PB), ás empresas parceiras e a todos os componentes da comissão organizadora do evento, cujos esforços foram essenciais para realização deste trabalho.

Among many rotating machinery vibration sources, there is one due to resonance, when the machine operation frequency crosses the natural frequency region. This study proposes a smart bearing that employs shape memory alloy NiTi helical springs for vibration-level reduction. This smart bearing is capable of dynamically changing its stiffness during machine acceleration or deceleration, keeping its natural frequency far from resonance. Activated by Joule effect and cooled by forced air convection, the prototype installed in horizontal rotating machinery reaches reduction of vibration amplitude of about 63% (root mean square) and 73% (Peak) at critical speed, with response time between 12–15 s. Compared with the results of the reference articles, satisfactory amplitude reduction and better response time were observed.