Vibrational energy transfer in coupled mechanical systems with nonlinear joints

This study investigates vibrational transfer and energy flow in nonlinearly coupled systems, each subjected to a harmonic force with different excitation frequency. A nonlinear joint having either smooth or non-smooth stiffness characteristics at the coupling interface is considered. The steady-state dynamic responses are obtained by a method of harmonic balance with alternating frequency and time and by a direct numerical integration. The time-averaged transmitted power is used to assess the direction of energy flow and the power transfer between the systems. It is shown that as the excitation frequency ratio increases, the point of zero net power transfer between subsystems moves to lower frequencies. The cubic stiffness nonlinearity mainly affects the power transfer in the vicinity of the second resonance frequencies. It is also shown that the second resonance frequencies of both subsystems and the point of zero net power transfer shift to higher frequencies when the bilinear stiffness ratio increases. For the power transfer curves, the bilinear stiffness ratio controls the location of the second resonance frequencies. Findings from this study can provide insights to aid design of interfacial joints with regards to vibration transfer in coupled systems under multi-frequency excitations. The study reveals energy flow mechanisms through joint structures, which should benefit their dynamic designs aiming at an enhanced vibration suppression performance.