Analytical and experimental study of thermoplastic polyurethane inclined beam isolator with quasi-zero stiffness and fractional derivative damping

Quasi-zero stiffness (QZS) isolators have been extensively studied for their excellent low-frequency isolation performance. However, damping in QZS isolation systems is often assumed to follow a linear viscous damping model, resulting in discrepancies between theoretical results and real-world scenarios. In this paper, an isolation system with QZS and fractional derivative (FD) damping is modeled and analyzed. The harmonic balance method is adopted to determine the steady-state responses and the displacement transmissibility. Then, a prototype of the QZS-FD isolator is fabricated using thermoplastic polyurethane material. The parameters of nonlinear stiffness and FD damping are obtained through parameter identification experiments. Numerical analysis is performed to validate the analytical results. Parametric studies are conducted to analyze the effect of varying the geometry parameters on isolation performance. Finally, a group of validation experiments is conducted. The experimental results agree well with the theoretical results, demonstrating the accuracy of the QZS-FD model.