[1] [1] AHMAD M M,KHAN N M,KHAN F U.Review of frequency up-conversion vibration energy harvesters using impact and plucking mechanism［J］.International Journal of Energy Research,2021,45(11):15609-15645.

[2] [2] JIANG W,WANG L,ZHAO L,et al.Modeling and design of V-shaped piezoelectric vibration energy harvester with stopper for low-frequency broadband and shock excitation［J］.Sensors and Actuators A:Physical,2021,317:112458.

[3] [3] FANG S,FU X,LIAO W.Modeling and experimental validation on the interference of mechanical plucking energy harvesting［J］.Mechanical Systems and Signal Processing,2019,134:106317.

[4] [4] DECHANT E,FEDULOV F,CHASHIN D V,et al.Low-frequency,broadband vibration energy harvester using coupled oscillators and frequency up-conversion by mechanical stoppers［J］.Smart Materials and Structures,2017,26(6):65021.

[5] [5] FANG S,FU X,LIAO W.Modeling and experimental validation on the interference of mechanical plucking energy harvesting［J］.Mechanical Systems and Signal Processing,2019,134:106317.

[7] [7] FU H,ZHOU S,YEATMAN E M.Exploring coupled electromechanical nonlinearities for broadband energy harvesting from low-frequency rotational sources［J］.Smart Materials and Structures,2019,28(7):75001.

[8] [8] HAN D,YUN K.Piezoelectric energy harvester using mechanical frequency up conversion for operation at low-level accelerations and low-frequency vibration［J］.Microsystem Technologies,2015,21(8):1669-1676.

[9] [9] WU Y,LI S,FAN K,et al.Investigation of an ultra-low frequency piezoelectric energy harvester with high frequency up-conversion factor caused by internal resonance mechanism［J］.Mechanical Systems and Signal Processing,2022,162:108038.

[10] [10] KUANG Y,YANG Z,ZHU M.Design and characterisation of a piezoelectric knee-joint energy harvester with frequency up-conversion through magnetic plucking［J］.Smart Materials and Structures,2016,25(8):85029.

[11] [11] WU Y,JI H,QIU J,et al.An internal resonance based frequency up-converting energy harvester［J］.Journal of Intelligent Material Systems and Structures,2018,29(13):2766-2781.

[12] [12] WU Y,QIU J,ZHOU S,et al.A piezoelectric spring pendulum oscillator used for multi-directional and ultra-low frequency vibration energy harvesting［J］.Applied Energy,2018,231:600-614.

[13] [13] PARK G,FU X,LIAO W H.Modeling of plucking piezoelectric energy harvesters with contact theory［C］//Portland,Oregon,United States：Society of Photo-optical Instrumentation Engineers.Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series,2017:101641E.