Comments on 'Drill-string horizontal dynamics with uncertainty on the frictional force' by TG Ritto, MR Escalante, Rubens Sampaio, MB Rosales [J. Sound Vib. 332 (2013) 145-153]

摘要

This paper analyzes the mechanical and mathematical models in "Ritto et al. (2013) [1]". The results are that: (1) the mechanical model is obviously incorrect; (2) the mathematical, model is not complete; (3) the differential equation is obviously incorrect; (4) the finite element equation is obviously not discretized from the corresponding mathematical model above, and is obviously incorrect. A mathematical model of dynamics should include the differential equations, the boundary conditions and the initial conditions. (C) 2016 Elsevier Ltd. All rights reserved.