Energy sharing between nonlinear structures by entropy modelling

Entropy and therefore the second principal of thermodynamics has been proposed originally from the Sapienza group to complete energy methods in vibroacoustics. The idea is to add entropy beside energy in making models for complex mechanical systems, especially in the field of high frequency vibrations. In fact, energy is naturally involved in the first law of thermodynamics (the energy conservation principle), but it does not involve any flow directions and "energy flow speed" information, governed indeed by inequality principles. However, this information are crucial. The eminent fact emerging from this method is that it applies indifferently to linear as well as to nonlinear systems. This element is surprising, but inherent with the use of the entropy concept in tandem with energy. Based on this model, the authors consider applications to real complex structures. To this aim two structural systems are investigated: coupled nonlinear beams and plates. The new horizon opened by the entropy-energy method is emphasized by the presented results.