Nonlinear oscillations
Modelling coupled torsional and axial motion in drilling systems.
Science
Nonlinear dynamics of drilling systems.
My research focuses on understanding complex oscillatory phenomena that arise during drilling system operation.
Research field
From mathematical models to field measurements
The research covers nonlinear oscillations and deterministic chaos in drilling systems, with particular attention to torsional and axial drill-string vibrations. The aim is to identify operating regimes in which stable motion transitions into irregular and potentially adverse oscillations.
The work combines analytical methods of nonlinear mechanics, numerical solutions of differential equations and dynamic diagnostics using Lyapunov exponents, Poincaré sections, time histories and phase portraits.
Experimental work
Vibration measurement during drilling
Vibrations are measured on a drilling rig for scientific research aimed at analysing tool and structural behaviour during ground drilling. The recorded signals make it possible to compare the real system with mathematical and numerical model results.
Measurements and data analysis are performed by Siniša Kraljević as part of his original scientific work. The research has no commercial purpose and is conducted solely to develop and validate scientific models.
Topics
Key research directions
Deterministic chaos
Identifying sensitivity to initial conditions and transitions to chaotic regimes.
Numerical diagnostics
Lyapunov exponents, Poincaré sections, time histories and phase portraits.
Experimental measurements
Vibration analysis on a real drilling rig and comparison with theoretical models.