On the shock performance of a hysteretic tri-stable vibration isolation system: Nonlinear phenomena and optimization

This work investigates the nonlinear response of a hysteretic multi-stable vibration isolation system under impulsive excitations. The multi-stable behavior is obtained by adding, in parallel with classical bearing devices, a mechanism with Negative Stiffness and superelastic hysteresis provided by Shape Memory Alloys (NS-SMA damping). By calibrating the design parameters, different types of stability can be achieved, such as bi-stability or tri-stability. The transition design parameter values between the different stability behaviors are identified analytically and define distinct space regions within the design parameters. The performances of the studied isolation system are numerically evaluated by computing the Shock Response Curves (SCR) and the performance maps are obtained by varying the design parameters and the amplitude of the motion. It is shown that the existence of two lateral wells in the potential profile can be exploited in order to trap the vibrating mass in them and effectively suppress accelerations and displacements. On the basis of this new observed phenomenon, renamed 'well trapping', the analytical equations for optimum parameter selection are obtained and furnished.