How does the frequency of vibrations affect the energy harvested from bridges?

The frequency of vibrations significantly affects the energy harvested from bridges by influencing the amount of mechanical energy available and the efficiency of energy conversion by the TENG. Bridges vibrate at different frequencies depending on the source of excitation, such as traffic, wind, or seismic activity. The amplitude of the vibrations is also frequency-dependent. Higher vibration frequencies generally correspond to higher kinetic energy, which can be harvested by the TENG. However, the TENG's energy conversion efficiency is also frequency-dependent, typically peaking at its resonance frequency. Matching the TENG's resonance frequency to the dominant vibration frequencies in the bridge is crucial for maximizing energy harvesting. If the vibration frequency is far from the TENG's resonance frequency, the energy harvesting efficiency will be significantly reduced. For example, a TENG designed to harvest energy from low-frequency vibrations caused by traffic might have a resonance frequency of a few Hertz. If the bridge is also subjected to high-frequency vibrations due to wind, a separate TENG with a higher resonance frequency could be used to harvest that energy.