000013088 001__ 13088
000013088 005__ 20161114160327.0
000013088 04107 $$aeng
000013088 046__ $$k2009-06-22
000013088 100__ $$aRitto T., G.
000013088 24500 $$aModeling uncertainties for local nonlinearities: application to the drill-string dynamics

000013088 24630 $$n2.$$pComputational Methods in Structural Dynamics and Earhquake Engineering
000013088 260__ $$bNational Technical University of Athens, 2009
000013088 506__ $$arestricted
000013088 520__ $$2eng$$aA probabilistic model is proposed to model uncertainties for local nonlinearities. The model is applied to a slender structure that turns and drills into rocks in search of oil, called drill-string, in which the local nonlinearity is the bit-rock interaction. The Maximum Entropy Principle is used to construct a probabilistic model for the nonlinear operator related to the bit-rock interaction model. A numerical model is developed using the Timoshenko beam theory and it is discretized by means of the Finite Element Method. The nonlinear dynamics analyzed considers a imposed rotation at the top, weight-on-hook, a fluid-structure interaction (that takes into account the drilling fluid that flows downwards the column and upwards the annulus), impact and rubbing between the column and the borehole, and finite strains (what couples axial, torsional and lateral vibrations). The development presented corresponds to a new approach to take into account model uncertainties in local nonlinearities using a probabilistic approach.

000013088 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000013088 653__ $$aprobabilistic model, local nonlinearities, nonlinear stochastic dynamics, drill-string dynamics, bit-rock stochastic model. Abstract. A probabilistic model is proposed to model uncertainties for local nonlinearities. The model is applied to a slender structure that turns and drills into rocks in search of oil, called drill-string, in which the local nonlinearity is the bit-rock interaction. The Maximum Entropy Principle is used to construct a probabilistic model for the nonlinear operator related to the bit-rock interaction model. A numerical model is developed using the Timoshenko beam theory and it is discretized by means of the Finite Element Method. The nonlinear dynamics analyzed considers a imposed rotation at the top, weight-on-hook, a fluid-structure interaction (that takes into account the drilling fluid that flows downwards the column and upwards the annulus), impact and rubbing between the column and the borehole, and finite strains (what couples axial, torsional and lateral vibrations). The development presented corresponds to a new approach to take into account model uncertainties in local nonlinearities using a probabilistic approach.

000013088 7112_ $$aCOMPDYN 2009 - 2nd International Thematic Conference$$cIsland of Rhodes (GR)$$d2009-06-22 / 2009-06-24$$gCOMPDYN2009
000013088 720__ $$aRitto T., G.$$iSoize, C.$$iSampaio, R.
000013088 8560_ $$ffischerc@itam.cas.cz
000013088 8564_ $$s5443571$$uhttps://invenio.itam.cas.cz/record/13088/files/CD115.pdf$$yOriginal version of the author's contribution as presented on CD, section: Uncertainty and reliability in computational structural dynamics - ii (MS).
000013088 962__ $$r13074
000013088 980__ $$aPAPER