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Orientador: Nilson Tadeu Mascia / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-11T20:02:44Z (GMT). No. of bitstreams: 1 Gagliardo_DeboraPierini_M.pdf: 2748592 bytes, checksum: 3f4f2274fa55f9b27f8663ca912c32fc (MD5) Previous issue date: 2008 / Resumo: As estruturas sanduíche têm despertado grande interesse e já estão bastante difundidas em diversos segmentos industriais, sendo suas principais utilizações nas indústrias aeroespacial, militar, naval e civil. Este fato se deve à sua propriedade de combinar alta rigidez à flexão e baixo peso, resultando em uma estrutura muito eficiente. Neste sentido, a análise e cálculo das estruturas sanduíche são de extrema importância no desenvolvimento de projetos de aplicação do mesmo. Neste trabalho, foram analisados os critérios de falha dos painéis, bem como os materiais e suas propriedades mecânicas, considerando as alterações e considerações que devem ser feitas nos projetos de acordo com as características do material. Na parte final dessa pesquisa, são apresentadas a teoria de cálculo e a rotina para elaboração de projetos relacionados com a construção civil utilizando as estruturas sanduíche, com ênfase em estruturas planas, tais como vigas e placas. Por fim emprega-se uma ferramenta, planilha eletrônica, para analisar e avaliar a aplicação de diversos materiais de construção em estruturas sanduíche. / Abstract: The sandwich structures have aroused great interest and have already been very widespread in several branches in industries, such as in the aerospace, military, naval and civil construction industries. This is due to their property to combine both high bending rigidity and the low weight, resulting in a very efficient structure. Thus, the analysis and also the calculation of sandwich structures are very important in developing the application projects. In this work, it was reviewed the failure criteria of the panels, as well as the materials and their mechanical properties, considering the changes and considerations that have to be performed in the project in accordance with the characteristics of the material. At the final part of this research, the theory of calculation and also the routine for development projects related with the civil construction using the sandwich structures are presented, with emphasis on flat structures, such as beams and plates. Finally employs is a tool, spreadsheet, to analyse and evaluate the implementation of various building materials in sandwich structures. / Mestrado / Estruturas / Mestre em Engenharia Civil

Different methods for the determination of cantilever properties in non-contact atomic force microscopy (NC-AFM) are under investigation. A key aspect is the determination of the cantilever stiffness being essential for a quantitative NC-AFM data analysis including the extraction of the tip-surface interaction force and potential. Furthermore, a systematic analysis of the displacement noise in the cantilever oscillation detection is performed with a special focus on the thermally excited cantilever oscillation. The propagation from displacement noise to frequency shift noise is studied under consideration of the frequency response of the PLL demodulator. The effective Q-factor of cantilevers depends on the internal damping of the cantilever as well as external influences like the ambient pressure and the quality of the cantilever fixation. While the Q-factor has a strong dependence on the ambient pressure between vacuum and ambient pressure yielding a decrease by several orders of magnitude, the pressure dependence of the resonance frequency is smaller than 1% for the same pressure range. On the other hand, the resonance frequency highly depends on the mass of the tip at the end of the cantilever making its reliable prediction from known cantilever dimensions difficult. The cantilever stiffness is determined with a high-precision static measurement method and compared to dimensional and dynamic methods. Dimensional methods suffer from the uncertainty of the measured cantilever dimensions and require a precise knowledge its material properties. A dynamic method utilising the measurement of the thermally excited cantilever displacement noise to obtain cantilever properties allows to characterise unknown cantilevers but requires an elaborative measurement equipment for spectral displacement noise analysis. Having the noise propagation in the NC-AFM system fully characterised, a proposed method allows for spring constant determination from the frequency shift noise at the output of the PLL demodulator with equipment already being available in most NC-AFM setups.