Piezoelectric energy harvesting in a nonlinear fluid-conveying pipe attached with quasi-zero-stiffness units

Quasi-zero-stiffness (QZS) mechanisms have been widely employed in engineering structures for vibration isolation. However, they also possess the potential for regulating energy harvesting performance, contributing to a multifunctional structure. Motivated by this characteristic, this study constructs a geometrically nonlinear fluid-conveying pipe outfitted with piezoelectric (PZT) layers for energy conversion and QZS units as tunable attachments. The PZT layers harvest the vibrations resulting from serving environments, and the QZS units shape the system's frequency response and place the effective harvesting band without active control. Practically, adjusting the vertical stiffness trades isolation against available motion amplitude, while the horizontal stiffness (negative-stiffness level) and the number of QZS units act as “tuning knobs” for band location. Within the fluid–structure interaction context, changes in flow velocity shift structural resonance bands, and the PZT–circuit resistance and excitation level govern the electromechanical coupling strength and output level. Such a novel design integrates low-frequency vibration isolation with tunable energy harvesting, offering both theoretical guidance and an engineering scheme for advanced fluid-conveying systems.