Nonlinear vibration of a loaded string in energy harvesting

Designing wideband energy harvesters using beam structures typically involves complexities, particularly in low-frequency and low-energy environments where the limitations of beam structures become more evident. To address these challenges, this study proposed a strategy for energy harvesting using a loaded-string system and established a theoretical model to investigate its performance. A parametric study was conducted for the string system, examining the effects of initial tension, mass location, material stiffness and excitation amplitude. The accuracy of the proposed model was verified through experimental validation. Both theoretical and experimental analyses observed a frequency shifting phenomenon, demonstrating the wideband characteristics of the system. Furthermore, the proposed string structure allows for convenient parameter adjustments, enabling the tuning of its natural frequency and operating bandwidth to meet more stringent practical requirements. The string system provides a new direction for designing energy harvesters to harness low-frequency energy from the ambient environment.