The Hong Kong Polytechnic University,
Keywords: anti-vibration, nonlinear stiffness, nonlinear damping
Summary:Inspired by the limb structures of animals/insects in motion vibration control, a bio-inspired X-shaped structure is systematically studied recently for understanding and exploring its advantageous nonlinear function in passive vibration isolation. The bio-inspired system consists of asymmetric articulations (of different rod lengths) with inside vertical and horizontal springs (as animal muscle) of different linear stiffness. Mathematical modeling and analysis of the X-shaped structure reveal that, (a) the system has very beneficial nonlinear stiffness which can provide flexible quasi-zero, zero and/or negative stiffness, and these nonlinear stiffness properties are adjustable or designable with structure parameters; (b) the asymmetric rod-length ratio and spring-stiffness ratio present very beneficial factors for tuning system equivalent stiffness; (c) the system loading capacity is also adjustable with the structure parameters which presents another flexible benefit in application; (d) the system has very beneficial nonlinear damping characteristics which can exhibit high damping as resonant frequencies when there is large vibration displacement but low at others. Experiments and comparisons with existing quasi-zero-stiffness isolators validate the advantageous features above. The results would provide an innovative bio-inspired solution to passive vibration control in various engineering practice.