مقایسه برداشت کننده‌های انرژی تک‌پایدار و دوپایدار تحت تحریک هم‌زمان جریان گردابی و مغناطیس

This paper presents a comparison between mono-stable and bi-stable energy harvesters under vortex-induced vibration excitation. In the bi-stable configuration, a pair of magnets is attached to the two bases of a cylinder, while in the mono-stable case, a single magnet is mounted on its body. To generate vortex shedding and the associated oscillatory lift forces, the cylinder is connected to the free end of a cantilever beam equipped with a piezoelectric layer. The aerodynamic forces are modeled using the modified Van der Pol equation, and the governing equation of the system vibrations is derived based on Hamilton’s principle.

The results indicate that when a magnet is mounted on the cylinder body, the system exhibits a mono-stable equilibrium position and a hardening behavior, which enhances energy harvesting, broadens the lock-in bandwidth, and shifts it toward higher wind speeds. In contrast, when magnets are installed on both bases of the cylinder, the system’s behavior strongly depends on the effective magnetic torque coefficient and the distances between the moving and fixed magnets. Depending on these parameters, the lock-in region may shift either to the left or to the right.