On dynamics of multi-mode systems: process damping effect & FRF modification

Official URL: http://risc01.sabanciuniv.edu/record=b1655719 (Table of Contents)

Dynamic response of machining systems is the primary information required for determining stability behavior. For the sake of simplicity, machining systems are normally treated as single mode systems in many researches. However, considering multi-mode characteristics and effects of multiple modes introduce new features to machining dynamics. In this thesis, two topics are studied on systems with multiple modes. First, the effect of process damping in multi-mode milling systems is investigated. Stability lobes diagrams are constructed through frequency domain solution and a time domain model is presented to simulate vibrations of the cutting tool. Effects of modes with different frequencies on stability frontier at low speeds are presented and verified experimentally. As the second part of this research, a methodology is developed to modify the dynamic response of structures with respect to their multi-mode characteristics. Using this methodology, the transfer function of a structure can be modified through interaction of structure’s modes. Tool-tip transfer function of a milling machine tool is suppressed and verification has been done through hammer impact tests. Keywords: Multi-mode systems, Process damping, Stability lobes diagram, Chatter, FRF modification, Modes interaction.