PARAMETRIC EXCITATION OF AN OFFSHORE RISER USING REDUCED-ORDER MODELS BASED ON BESSEL-TYPE MODES: ASSESSMENT ON HYDRODYNAMIC COEFFICIENTS EFFECTS
Guilherme Rosa Franzini1; Thiago Dias1; C Mazzilli1; Celso Pupo Pesce1
1 Escola Politécnica da Universidade de São Paulo
Resumo
The effects of the added mass and mean drag coefficients on the post-critical transversal vibrations of an offshore-riser mathematical model are discussed when it is subjected to parametric excitation induced by harmonic axial displacements at the top. A single-degree-of-freedom nonlinear reduced-order model is obtained from the continuum beam equation of motion, using Bessel-type modes. After numerical integration, using a Runge-Kutta scheme, maps of post-critical amplitude are presented as functions of the amplitude and frequency of the parametric excitation. Results are confronted with the standard analysis that usually assumes both hydrodynamic coefficients to be constant.
Palavras-chave: reduced-order model; parametric excitation; Bessel-like modes