Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
SENSITIVITY ANALYSIS OF THE TORSIONAL VIBRATION OF A DRILL STRING USING SOBOL INDICES
Submission Author:
Thiago Ritto , RJ
Co-Authors:
Thiago Ritto, Edison Fabian Caballero Perez
Presenter: Thiago Ritto
doi://10.26678/ABCM.COBEM2021.COB2021-1603
Abstract
We are interested in the nonlinear torsional dynamics of a drill string. The aim of this work is to investigate the torsion vibration severity sensitivity with respect to the system parameters. A one degree-of-freedom system is considered, where an imposed rotational speed is imposed at the top and a nonlinear bit-rock interaction occurs at the bottom. Some parameters of the system are considered uncertain (rotation at the top, weight-on-bit, bit-rock interaction parameters) and a probabilistic model is constructed from them. The Sobol strategy is employed to obtain the global sensitivity indices. To better visualise the results, a normalisation is proposed where the maximum variance obtained for all the analyses is considered as a reference to construct the sensitivity maps. The results show that the response of the system is more sensitive to a specific parameter of the bit-rock interaction, and is less sensitive to the rotational speed at the top and the weight-on-bit.
Keywords
structural dynamics, nonlinear drill string, Global sensitivity analysis, stochastic dynamics, Sobol
