Synergizing stopper mechanisms, coil configurations and quasi-linearity for enhanced adaptability in dual-beam 2DOF electromagnetic energy harvesters

Abstract

This study investigates the benefits and challenges of asymmetric stopper control and different coil connection modes in dual beam harvester designs, aiming to optimize vibration energy harvesting systems for enhanced renewable energy applications and self-powered devices. The work demonstrates that the dynamic response and potential of the system affect the cantilever’s damping-stiffness matrix during impacts. General engineering analysis established limits for non-quasi-static linearity at stress ratio of 0.80 is the operational safety threshold before full fatigue occurs. Analytical and experimental validations at equivalent stress/bending moment reveal that polyvinylchloride laminate (PVC) attained the largest damping-critical stress gradient compared to other polymeric (polyether ether ketone (PEEK) and Glassfiber) or nonpolymeric (stainless steel and aluminum) material. Therefore, polymeric showed quick fatigue stress at respective maximum non-quasi-linear contact stiffness of 0.1150, 0.9495, 0.8575, 2.6352, 1.2206 $MN{m}^{-\frac{3}{2}}$ at 80. 00 % fatigue stress level. Also, within tested the polymeric family, high damping-critical stress gradient indicates capacity for larger microstructural deformation before failure such that quasi linear weak softening approximation is acceptable when maximum bending to fatigue stress ratio ≤0.8. In evaluating the electrical connections, it was found that while individual transducer coils can power dual load sensors concurrently, bandwidth is compromised with materials exhibiting lower damping-critical stress gradients. Notably, the normalized power density improved by 91.45 %, reaching ${Wm}^{-5}{s}^5$ and 2.435 ${Wm}^{-5}{s}^5$ with fiberglass-aluminum cantilever pairs. Additionally, increasing the stopper gap enhances post-resonance bandwidth by up to 68.35 %, although this results in a power reduction of 31.40 %. These results underscore the trade-offs between harvested power and bandwidth, highlighting the efficacy of pairing polymeric and non-polymeric cantilevers in dual beam systems for optimized energy harvesting.