• Title/Summary/Keyword: Vibrational Film

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Responses and Stresses of Structural Vibration of a Camshaft (캠축의 구조 진동 응답 및 응력)

  • Choi, Myung-Jin
    • The Journal of the Acoustical Society of Korea
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    • v.32 no.3
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    • pp.208-213
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    • 2013
  • To get vibration responses, a camshaft is modelled as an unbalanced multiple rotor bearing system. Because of complex geometry and complicated load conditions, the finite element method is used. After the finite element equation of the system is constructed, Newmark's method is used to get the vibration responses. Whirl vibration responses of a V-8 engine camshaft are estimated and compared with measured responses. After the fluctuating stresses are obtained, fatigue analysis is performed based upon the modified Goodman's equation. Stress concentration effects are considered. In the whirl vibration of camshafts, the bending effect is dominant, and the bending deformation is dependent upon the span length between the adjacent bearing journals. For high speeds, the fluctuations of excitation forces are large, and it is known that nonlinear time varying bearing coefficients should be used for analysis.

Development and Characterization of Hafnium-Doped BaTiO3 Nanoparticle-Based Flexible Piezoelectric Devices (Hf 도핑된 BaTiO3 나노입자 기반의 플렉서블 압전 소자 개발 및 특성평가)

  • HakSu Jang;Hyeon Jun Park;Gwang Hyeon Kim;Gyoung-Ja Lee;Jae-Hoon Ji;Donghun Lee;Young Hwa Jung;Min-Ku Lee;Changyeon Baek;Kwi-Il Park
    • Journal of Sensor Science and Technology
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    • v.33 no.1
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    • pp.34-39
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    • 2024
  • Energy harvesting technology that converts the wasted energy resources into electrical energy is emerging as a semipermanent power source for self-powered electronics and wireless low-power sensor systems. Among the various energy conversion techniques, flexible piezoelectric energy harvesters (f-PEHs), using materials with piezoelectric effects, have attracted significant interest because they can harvest a small mechanical energy into electrical signals without constraints of time and space in various environments. In this study, we used a flexible piezoelectric composite film fabricated by dispersing BaHfxTi(1-x)O3 (x = 0, 0.01, 0.05, 0.1) piezoelectric powders inside a polymeric matrix to facilitate f-PEHs. The fabricated f-PEH with optimal Hf contents (x = 0.05) generated a maximum output voltage of 0.95 V and current signal of 130 nA with stable electrical/mechanical disabilities under periodically bending deformations. In addition, we demonstrated a cantilever-type f-PEH and investigated its potential as a sensor by characterizing the output performance under mechanical vibrations at various frequencies. This study provides the breakthrough for realizing self-powered energy harvesting and sensing systems by adopting the lead-free piezoelectric composites under vibrational environments.