An Assessment of HDPE Viscoelastic Behavior Effects on the Bending of Offshore Flexible Pipes
Caio C. P. Santos1; Celso P. Pesce1; Marcos A. Rabelo2; Roberto Ramos Jr1
1 Offshore Mechanics Laboratory (LMO) - Escola Politécnica, University of São Paulo - SP, Brazil; 2 Federal University of Santa Catarina, Joinville, SC, Brazil
doi:10.20906/CPS/COB-2015-1469
Resumo
Flexible pipes are complex structures composed by several metallic helical layers and polymeric extruded tubes, composed in concentric arrangements. Numerous analytical and numerical models exist nowadays, enabling analysts to assess stress and strain fields in the structural components of flexible pipes. In these models, internal friction is a common feature, being its effect associated to the hysteretic bending behavior. On the other hand, it is well known that flexible pipes bending stiffness is strongly dominated by the extruded external polymeric layer. In spite of that, existing numerical and analytical models do not take into account the viscoelastic mechanical behavior, which characterizes most of the polymeric external layers. The present work addresses this particular point numerically. Results from a recent experimental campaign, meant to assess the viscoelastic response of pipes made of high-density polyethylene (HDPE), are used to generate a representative model. Such a model is then applied in a case study to assess and discuss the viscoelastic effect on bending of a typical flexible pipe, through an innovative Finite Element Analysis approach.
Palavras-chave: Flexible pipes; Bending; HDPE; Viscoelastic behavior; Experimental investigation; FE analysis