Broadband Nonlinear Vibration Isolation for a Friction Dynamic System via Quasi-Zero Stiffness Isolator

Vibration isolation is necessary for reducing or suppressing unwanted vibrations in the packaging box outside the stowed film structure at launch. Vibration isolation characteristics of a passive nonlinear quasi-zero stiffness (QZS) isolator are investigated to suppress vibration for a two-degree-of-freedom (2-DOF) friction dynamic system. The vibration isolation system is modeled by a pair of horizontal precompression springs to generate negative stiffness and one vertical spring to provide support stiffness. Then the approximate analytic solution of this system is obtained by the harmonic balance method and compared with the solution derived for a linear system after numerical validation. The results show that the QZS isolator can effectively suppress the vibration transmission of the two primary structures simultaneously. Moreover, the QZS isolator achieves a broadband suppression effect according to the work–frequency curve done by friction. Wavelet spectrum analysis also shows that the QZS isolator reduces frictional work by suppressing the multifrequency energy transfer between the 2-DOF system, thereby reducing the damage to two primary structures. Hence, these results indicate that the QZS isolator composed of three springs has the ability to achieve efficient vibration reduction for a friction dynamic system.