Calming Vibrational Systems by Optimized Placement of Novel Situation-Aware Frictional Damper Elements

点击翻译按钮获取中文摘要

Continuously increasing costs of fossil energy carriers and tightening legal regulations in the last years require high energy efficiency in all types of machinery. Consequently, in order to increase efficiency, the impact of friction and other damping influences is systematically reduced. On the other hand, the strong trend to light weight design makes mechanical structures even more sensitive against vibrational excitation. Thus, it is necessary to calm vibrations effectively and tightly focused without influencing the desired operation and decreasing the efficiency of a mechanism as a whole. Hence, the development of new types and innovative designs of damping devices (DD) is inevitable for protecting machines from undesired vibrations.Usually neglected nonlinearities of damping forces may offer a particularly huge potential to design situation-dependent behavior without the need to implement a controller or supply additional energy. Especially dry friction forces with stick-slip transitions make it possible to design elements that switch their behavior and thus can serve as basic components for DDs adapting themselves to the current situation.For 1-DoF-systems the impact of dry friction damping on forced oscillations has been extensively discussed in the literature. Friction based DDs are mainly based on the dissipative properties of friction forces and either utilize the constructive friction which is inherently present in almost all joints or are based on deliberately designed machine components with localized or distributed friction. Unfortunately significantly less attention has been payed to the effects occurring in systems with many DOF and especially to the optimal placement of the friction based dissipative elements and to the strongly non-linear interactions between them and the original structure. The main objective of the project is to investigate how novel friction-based DDs can be used for the focused reduction of forced vibrations. Beyond the analysis of these devices, also efficient approaches will be devised, enabling to configure and place them on mechanical systems in an optimal way. In order to achieve this overall goal, various DDs based on appropriate combinations of four basic elements (sequential friction-spring, modulated normal load, sequential backlash-friction and distributed friction) will be compared with respect to their ability to provide energy-efficient and situation-aware behavior. Analytical methods will be developed which allow to evaluate the efficiency of these devices in oscillating systems in a reliable way. Using both analytical and numerical optimization techniques, the aspect of a sensible placing of the DDs within the basic structure will be investigated, taking interactions between these strongly non-linear elements into account. The most promising devices will be prototyped and tested experimentally.