Experimental Analysis of a Vertical and Flexible Cylinder in Water: Response to Top Motion Excitation and Parametric Resonance

Autor(es)

Franzini, Guilherme R. ^[1] ; Pesce, Celso P. ^[2] ; Salles, Rafael ^[2] ; Goncalves, Rodolfo T. ^[3] ; Fujarra, Andre L. C. ^[3] ; Mendes, Pedro ^[4]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Escola Politecn, Dept Struct Engn & Geotech, BR-38005508 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Escola Politecn, Offshore Mech Lab LMO, BR-38005508 Sao Paulo, SP - Brazil

^[3] Univ Sao Paulo, Escola Politecn, Numer Offshore Tank TPN, BR-38005508 Sao Paulo, SP - Brazil

^[4] Petrobras SA, Ctr Res & Dev, BR-21941915 Rio De Janeiro, RJ - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME; v. 137, n. 3 JUN 2015.
• Citações Web of Science: 14

Resumo

Experiments with a vertical, flexible, and submerged cylinder were carried out to investigate fundamental aspects of risers dynamics subjected to harmonic excitation at the top. The flexible model was designed aiming a high level of dynamic similarity with a real riser. Vertical motion, with amplitude of 1% of the unstretched length, was imposed with a device driven by a servomotor. Responses to distinct exciting frequency ratios were investigated, namely, f(t):f(N,1) = 1: 3; 1: 1; 2: 1, and 3:1. Cartesian coordinates of 43 monitored points positioned all along the span were experimentally acquired by using an optical tracking system. A simple Galerkin's projection applied for modal decomposition, combined with standard Mathieu chart analysis, led to the identification of parametric resonances. A curious finding is that the Mathieu instability may simultaneously occur in more than one mode, leading to interesting dynamic behaviors, also revealed through standard power spectra analysis and displacement scalograms. (AU)

• Processo FAPESP: 13/09802-2 - Estudo do escoamento ao redor de cilindros inclinados e de baixa razão de aspecto com vistas ao movimento induzido pela emissão de vórtices (MIV) de plataformas flutuantes
• Beneficiário: Guilherme Rosa Franzini
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado