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The mechanisms leading to torsional vibrations in drilling systems are considered in this paper. Thereto, a drill string model of the axial and torsional dynamics is proposed, where coupling is provided by a rate-independent bit-rock interaction law. Analysis of this model shows that the fast axial dynamics exhibit an axial stick-slip limit cycle. This generates an apparent velocity-weakening effect...
Considering the deficiency in cutting conditions optimization of milling process, based on the dynamic modeling of milling process, a dynamic simulation software of complex cutting conditions milling process was developed successfully in Matlab-VB.net hybrid environment. On the basis of measurement of machining system's dynamics and corresponding experimental modal analysis results, the simulation...
In order to suppress the torsional vibration of rotary machine, a PI controller was analytically derived based on stability of the closed-loop system and Hinfin mixed sensitivity function. This novel design procedure is adapted to some unstable and critically stable systems, and a single parameter T1 is included in the controller, which can be determined by the disturbance rejection capability and...
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