Bending-torsion coupling and dynamic stability of an asymmetric clamped-clamped rotating energy harvester

Condition monitoring of high-speed rotating components, such as helicopter tail shafts, relies on embedded self-powered sensor nodes. Clamped-clamped beams, with their bidirectional constraints and large-deflection nonlinearity, provide a feasible structure for confined rotational spaces. However, most existing rotating harvester models are developed under ideal alignment assumptions and mainly focus on output enhancement, while the stability degradation caused by assembly-induced spatial asymmetry remains insufficiently clarified. This paper develops a distributed-parameter electromechanical model for an asymmetric clamped-clamped rotating energy harvester with radial offset, axial offset, and lateral eccentricity. Derived via the extended Hamilton principle and Galerkin method, the model is validated experimentally on a rotating test bench. Results indicate that lateral eccentricity creates a dynamic moment, transferring energy between the first bending and torsional modes. Phase space analysis reveals a transition from a stable period-one orbit to transient chaos, followed by a boundary crisis that interrupts the harvesting bandwidth with an energy valley (e.g., 2200–2500 rpm at e = 3 mm). Radial offsets generate static loads that suppress peak power (from 110 mW to 10 mW at r = 0.6 mm). Axial offsets delay the jump speed without breaking Duffing hysteresis. In contrast, lateral eccentricity interrupts bandwidth continuity. Reducing the magnet moment of inertia weakens bending–torsion modal overlap; at 0.6 Jmc, this strategy suppresses the energy valley and improves bandwidth continuity more effectively than preload compensation. These findings provide quantitative guidance for assembly tolerance control, bandwidth-continuity design, and structural compensation of self-powered sensing nodes in confined rotating spaces.