Energy harvesting below the onset of flutter

Abstract

This work demonstrates preliminary results on energy harvesting from a linearly stable fluttertype system with circulatory friction forces. Harmonic external forcing is applied to study the energy flow in the steady sliding configuration. In certain parameter ranges negative excitation work is observed where the external forcing allows to pull part of the friction energy out of the system and thus makes energy harvesting possible. Studies reveal that this behavior is largely independent of the flutter point and thus that it is primarily controlled by the excitation. Contrary to existing energy harvesting approaches for such systems, this approach uses external forcing in the linearly stable regime of the oscillator which allows to control vibrations and harvest energy on demand.

Prediction and Suppression of Chaotic Instability in Brake Squeal

“…Comparisons of the full numerical solutions and the conservative analytical criteria derived in section 2.3 were performed and used to identify conditions under which chaotic instability occurs and its suppression over a range of friction coefficients, modal damping constants, sprag angles and brake pressures. The system nominal parameter conditions were chosen according to fundamental and real investigations of brake squeal, [21], [28], [15], [18] and [24] as described in Table 1.…”

“…Model [21], [28], [18] Real Brake system Model [15] Structural vibration parameters The nonlinear friction model of equation ( 5) was tuned experimentally to a typical automobile pad (Volvo 850/S70 X8 pad) [24]. Note that lower friction curve steepness parameters, α , to [18] were used to provide the same accuracy of fit while enhancing the numerical stability and speed of the solver.…”

“…A fundamental degree of freedom brake squeal model [21], [28], [18] was investigated for nonlinear squeal instability as the friction coefficient was changed. The fundamental model parameters were chosen as described in [18] and are listed in the first column of Table . 1.…”

Investigation of Piezoelectric Energy Harvesting via Nonlinear Friction-Induced Vibration

“…By using a wobbling disc energy harvester, Heffel and Hagedorn [55] found that converting FIV energy to electrical energy could lead to a broadband applicability. In addition, in a recent work performed by Stender et al [48], external forcing was verified to be able to pull part of the friction energy out of the system and thus make energy harvesting possible in certain parameter ranges. ese studies are definitely necessary for realizing energy harvesting via FIV.…”

“…Considering that the FIV is uncontrollable and unpredictable due to its inherently irregular nature and it is undesirable and harmful in most cases; thus a large amount of research on FIV mainly focuses on understanding its mechanism and searching for potential effective approaches to improve FIV of friction systems [43][44][45][46][47]. Meanwhile, from another perspective, sometimes the FIV can be useful if this kind of vibration energy is collected in a certain way and converted to electrical energy, which can be thought of as "makes the best out of an undesirable situation" [48]. Furthermore, FIV occurs simultaneously in both the normal and tangential directions of the friction system, indicating that the vibration energy in both directions can be collected [8].…”