Targeted energy transfer in powertrains to reduce vibration-induced energy losses

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Systems that generate and transmit power (powertrains) in a variety of engineering applications (automotive, aeronautical, marine, turbo-machinery, renewable energy) can suffer from applied disturbances such as impact and impulsive loading, periodic or random excitation. Modern light weight philosophy and increased engine/generator output power often exacerbate the situation. The resulting vibrations increase fuel consumption unavoidably, which also results in increased emissions. Recent studies have demonstrated the potential to save up to 9.3 million tons of automotive CO2 emissions by reducing the effect of cyclic irregularities of internal combustion engines in automotive transmissions (Joachim et al. "How to minimize power losses in transmissions, axles and steerings", VDI Gears 2011). The use of palliatives to suppress drivetrain vibrations increases the product cost. Furthermore, component wear and fatigue are other effects, adding to operational costs.Passively controlled transfer of vibrational energy in coupled systems to a target, where the excess or residual energy eventually diminishes, is a - relatively - new concept called Targeted Energy Transfer (TET). It is based on imposing conditions upon nonlinear resonance between a primary source (the powertrain in this case) and a secondary system in order to achieve transfer of energy from one system to the other in an irreversible manner. The secondary system possesses essential stiffness nonlinearity, thus altering the global dynamics because of the lack of a preferential resonant frequency. Therefore, the latter can act as a Nonlinear Energy Sink (NES) over a broad range of excitation frequencies.Thus, the overarching question in this proposal is "How can one design and develop a sustainable vibration reduction technology for powertrains using the modern TET research method?" This is undertaken with the view of maximising the benefits and limiting the costs to the UK plc, as well as the consumers. Currently, the automotive industry represents 9.2% of the total UK exports (source: Society of Motor Manufacturers and Traders). The program of research is split into a number of work-packages in order to address the stated key-objective questions:1. How can a TET mechanism be conceived for powertrain systems to effectively absorb/harvest the excess energy? Therefore, parametric models for scenario-building simulations will be developed to fundamentally understand the energy exchange mechanisms.2. How much energy would be absorbed by the NES and under what input conditions? Is this method robust to typical variations (and uncertainties) in system parameters, initial conditions and external excitations encountered in powertrain dynamics? How do TET-based designs compare to alternative currently commercialised designs? The latter will be examined at component and system levels.3. Could the TET mechanism be used for energy harvesting purposes in real powertrain systems?4. Lastly, effort will be expended in closing the loop between the above questions and consolidating on practical methods of implementing the outcomes of 1-3 above in powertrains according to specific design objectives.The collaboration between the different project partners will be tightly managed, so that the project objectives are achieved. The generated methods will be made available in the public domain. Automotive systems represent common operating features of powertrains across a variety of engineering applications. Hence, they have been selected for this fundamental generic research. The knowledge and experience accrued in this project can be expanded to a variety of large and small scale power transmission applications for vibration reduction, including aeronautics, marine, renewable energy (wind turbines) and micro-electro-mechanical systems.