<aside> 💡
Researchers: [Seokgyu Yang], [Somya Ranjan Patro], [Hemant Sharma]
</aside>
<aside> 💡
Collaborators: Prof. Jaehyung Ju at Shanghai Jiao Tong University [Lab website]
</aside>
<aside> 💡
Themes: Engineering applications
</aside>
We design, optimize and fabricate a beam structure made of spring steel with a compliant mechanism (Fig. 1(a)) that can passively evade resonant frequencies. This structure exhibits two distinct stiffness modes: a HS (High-stiffness) state (Fig. 1(b) red area) and a QZS (Quasi-zero-stiffness) state (Fig. 1(b) blue area). By optimizing key design parameters using finite element methods (FEM) and surrogate optimization, we tune the structure’s force-displacement curve to exhibit two stable states, HS and QZS, under the loading conditions. While the conventional QZS isolators are attractive for low-frequency vibration isolation due to their reduced effective stiffness, they still develop excessive oscillatory motions in low-frequency resonances. The proposed structure passively evades such low-frequency resonances by switching to the HS mode, thereby preventing excessive structural vibrations. The resonance in the HS mode can be evaded in the same manner by reverting to the QZS configuration. We confirm this mechanism computationally via nonlinear vibration simulations, demonstrating passive resonance evasion near resonance frequencies. This passive stiffness-switching strategy opens new possibilities for designing adaptive mechanical metamaterials and systems with enhanced vibration robustness.
