This study presents a new design of a piezoelectric-electromagnetic energy harvester to enlarge the frequency bandwidth and obtain a larger energy output.This harvester consists of a primary piezoelectric energy harve...This study presents a new design of a piezoelectric-electromagnetic energy harvester to enlarge the frequency bandwidth and obtain a larger energy output.This harvester consists of a primary piezoelectric energy harvesting device,in which a suspension electromagnetic component is added.A coupling mathematical model of the two independent energy harvesting techniques was established.Numerical results show that the piezoelectric-electromagnetic energy harvester has three times the bandwidth and higher power output in comparison with the corresponding stand-alone,single harvesting mode devices.The finite element models of the piezoelectric and electromagnetic systems were developed,respectively.A finite element analysis was performed.Experiments were carried out to verify the validity of the numerical simulation and the finite element results.It shows that the power output and the peak frequency obtained from the numerical analysis and the finite element simulation are in good agreement with the experimental results.This study provides a promising method to broaden the frequency bandwidth and increase the energy harvesting power output for energy harvesters.展开更多
This paper presents a type of vibration energy harvester combining a piezoelectric cantilever and a single degree of freedom (SDOF) elastic system. The main function of the additional SDOF elastic system is to magnify...This paper presents a type of vibration energy harvester combining a piezoelectric cantilever and a single degree of freedom (SDOF) elastic system. The main function of the additional SDOF elastic system is to magnify vibration displacement of the piezoelectric cantilever to improve the power output. A mathematical model of the energy harvester is developed based on Hamilton's principle and Rayleigh-Ritz method. Furthermore, the effects of the structural parameters of the SDOF elastic system on the electromechanical outputs of the energy harvester are analyzed numerically. The accuracy of the output performance in the numerical solution is identified from the finite element method (FEM). A good agreement is found between the numerical results and FEM results. The results show that the power output can be increased and the frequency bandwidth can be improved when the SDOF elastic system has a larger lumped mass and a smaller damping ratio. The numerical results also indicate that a matching load resistance under the short circuit resonance condition can obtain a higher current output, and so is more suitable for application to the piezoelectric energy harvester.展开更多
Wire race ball bearings have been widely used in high-tech weapons. The preload of a wire race ball bearing is crucial in engineering applications. In this study, a more effective approach is proposed for exact determ...Wire race ball bearings have been widely used in high-tech weapons. The preload of a wire race ball bearing is crucial in engineering applications. In this study, a more effective approach is proposed for exact determination of the wire race ball bearing preload. A new mathematical model of the preload and the starting torque of the wire race ball bearing was built using the theorem of the 3D rolling friction resistance and the non-conforming contact theory. Employing a wire race ball bearing with a 1000 mm diameter used in a specific type of aircraft simulating rotary table, the numerical analysis in MATLAB~ showed that the preload magnitude can be controlled in the range of 130–140 μm. As verification, the experimental results were in agreement with the theoretical results, and confirm the feasibility of this method. This new approach is more exact in the preload range of 10–158 μm than that computed by the numerical method reported in our previous work (Shan et al., 2007b). This implies that the present method contributes to more effectively preventing rolling noise, overturning moments and wear of the wire race ball bearing. The current research provides critical technical support for the engineering application of wire race ball bearings with large diameters.展开更多
基金Project supported by the National Natural Science Foundation of China(No.51077018)the Fundamental Research Funds for the Central Universities(No.HIT.NSRIF.2014059),China
文摘This study presents a new design of a piezoelectric-electromagnetic energy harvester to enlarge the frequency bandwidth and obtain a larger energy output.This harvester consists of a primary piezoelectric energy harvesting device,in which a suspension electromagnetic component is added.A coupling mathematical model of the two independent energy harvesting techniques was established.Numerical results show that the piezoelectric-electromagnetic energy harvester has three times the bandwidth and higher power output in comparison with the corresponding stand-alone,single harvesting mode devices.The finite element models of the piezoelectric and electromagnetic systems were developed,respectively.A finite element analysis was performed.Experiments were carried out to verify the validity of the numerical simulation and the finite element results.It shows that the power output and the peak frequency obtained from the numerical analysis and the finite element simulation are in good agreement with the experimental results.This study provides a promising method to broaden the frequency bandwidth and increase the energy harvesting power output for energy harvesters.
基金supported by the National Natural Science Foundation of China(No.51077018)the Heilongjiang Provincial Natural Science Fundation(No.F201219)the Program for Young Teachers Scientific Research in Qiqihar University(No.2012k-Z12),China
基金Project supported by the National Natural Science Foundation of China (No. 51077018)the Science and Technology Planning Project of Qiqihar (No. GYGG2010-02-1), China
文摘This paper presents a type of vibration energy harvester combining a piezoelectric cantilever and a single degree of freedom (SDOF) elastic system. The main function of the additional SDOF elastic system is to magnify vibration displacement of the piezoelectric cantilever to improve the power output. A mathematical model of the energy harvester is developed based on Hamilton's principle and Rayleigh-Ritz method. Furthermore, the effects of the structural parameters of the SDOF elastic system on the electromechanical outputs of the energy harvester are analyzed numerically. The accuracy of the output performance in the numerical solution is identified from the finite element method (FEM). A good agreement is found between the numerical results and FEM results. The results show that the power output can be increased and the frequency bandwidth can be improved when the SDOF elastic system has a larger lumped mass and a smaller damping ratio. The numerical results also indicate that a matching load resistance under the short circuit resonance condition can obtain a higher current output, and so is more suitable for application to the piezoelectric energy harvester.
基金Project supported by the National Natural Science Foundation of China (No. 50905039)the Natural Science Foundation of Hei-longjiang Province (No. E200924), China
文摘Wire race ball bearings have been widely used in high-tech weapons. The preload of a wire race ball bearing is crucial in engineering applications. In this study, a more effective approach is proposed for exact determination of the wire race ball bearing preload. A new mathematical model of the preload and the starting torque of the wire race ball bearing was built using the theorem of the 3D rolling friction resistance and the non-conforming contact theory. Employing a wire race ball bearing with a 1000 mm diameter used in a specific type of aircraft simulating rotary table, the numerical analysis in MATLAB~ showed that the preload magnitude can be controlled in the range of 130–140 μm. As verification, the experimental results were in agreement with the theoretical results, and confirm the feasibility of this method. This new approach is more exact in the preload range of 10–158 μm than that computed by the numerical method reported in our previous work (Shan et al., 2007b). This implies that the present method contributes to more effectively preventing rolling noise, overturning moments and wear of the wire race ball bearing. The current research provides critical technical support for the engineering application of wire race ball bearings with large diameters.