• Smart Structures and Systems
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• 제16권4호
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• pp.579-591
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• 2015

This paper investigates a magnetoelectric (ME) vibration energy harvester that can scavenge energy in arbitrary directions in a plane as well as wide working bandwidth. In this harvester, a circular cross-section cantilever rod is adopted to extract the external vibration energy due to the capability of it's free end oscillating in arbitrary in-plane directions. And permanent magnets are fixed to the free end of the cantilever rod, causing it to experience a non-linear force as it moves with respect to stationary ME transducers and magnets. The magnetically coupled cantilever rod exhibits a nonlinear and two-mode motion, and responds to vibration over a much broader frequency range than a standard cantilever. The effects of the magnetic field distribution and the magnetic force on the harvester's voltage response are investigated with the aim to obtain the optimal vibration energy harvesting performances. A prototype harvester was fabricated and experimentally tested, and the experimental results verified that the harvester can extract energy from arbitrary in-plane directions, and had maximum bandwidth of 5.5 Hz, and output power of 0.13 mW at an acceleration of 0.6 g (with $g=9.8ms^{-2}$).

• 대한토목학회논문집
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• 제32권6A호
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• pp.379-387
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• 2012

본 연구에서는 새로운 에너지 수확용 Multi-layer 블록 구조를 제시하고 고체 및 Shell 유한 요소를 사용하여 다양한 기하학적 형상 변화에 대한 자유진동 특성을 분석하고 압전 성능을 실험적으로 평가한다. 본 연구에서 제시하는 블록 구조에 대한 2차원 및 3차원 유한요소 모델은 해석의 정확성 뿐 만 아니라 전체 진동 모드를 정확히 보여준다는 점에서 장점을 갖는다. ABAQUS가 적용된 유한요소 모델은 다양한 Tip mass 및 PZT 변화에 따른 Multi-layer 블록 구조의 자유진동을 분석하기 위하여 사용되었다. 특히, 본 연구에서 제시한 결과는 블록구조 전체의 기하학적 형상, Tip mass 및 Hole의 유무, Tip mass 및 PZT의 위치변화 등에 대하여 국부 및 전체 진동 모드에 미치는 중요한 영향들에 대하여 초점을 둔다. 또한, 실험실 규모의 실제 모형 실험을 수행하여 개발한 에너지 블록구조의 발전성능을 평가하였다.

• 한국전기전자재료학회논문지
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• 제26권11호
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• pp.846-851
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• 2013

Recently, energy harvesting technologies are considered as the great alternatives to reduce the dependency on secondary batteries. In this paper, we proposed PCB type energy harvester which can be directly integrated with other electronic components on same board. To form the three dimensional coil structure, two PCBs with patterned metal lines are solder bonded. For magnetic induction, inside of coil structure was filled with magnetic substance and rotary motioned external magnets are applied to near the harvester. The effects of metal wire width on PCB, thickness of magnetic substance, and frequency of rotary motion on energy harvesting performance are analyzed by computer simulation and experiments. Experimental results showed 29.89 ${\mu}W$ of power generation performance at the frequency of 5.2 Hz and it is shown that designed harvester can be effectively applied on vibration environment with very limited frequency.

• Advances in aircraft and spacecraft science
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• 제2권3호
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• pp.275-302
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• 2015

Theoretical and numerical assessments of approximate evaluations and simplified analyses of piezoelectric structures transverse shear modal effective electromechanical coupling coefficient (EMCC) are presented. Therefore, the latter is first introduced theoretically and its approximate evaluations are reviewed; then, three-dimensional (3D) and simplified two-dimensional (2D) plane-strain (PStrain) and plane-stress (PStress) piezoelectric constitutive behaviors of electroded shear piezoceramic patches are derived and corresponding expected short-circuit (SC) and open-circuit (OC) frequencies and resulting EMCC are discussed; next, using a piezoceramic shear sandwich beam cantilever typical benchmark, a 3D finite element (FE) assessment of different evaluation techniques of the shear modal effective EMCC is conducted, including the equipotential (EP) constraints effect; finally, 2D PStrain and PStress FE modal analyses under SC and OC electric conditions, are conducted and corresponding results (SC/OC frequencies and resulting effective EMCC) are compared to 3D ones. It is found that: (i) physical EP constraints reduce drastically the shear modal effective EMCC; (ii) PStress and PStrain results depend strongly on the filling foam stiffness, rendering inadequate the use of popular equivalent single layer models for the transverse shear-mode sandwich configuration; (iii) in contrary to results of piezoelectric shunted damping and energy harvesting popular single-degree-of-freedom-based models, transverse shear modal effective EMCC values are very small in particular for the first mode which is the common target of these applications.