| Structural health monitoring is one of key technologies of improving the safety of critical engineering structures and reducing maintenance costs.How to provide long-term reliable power for wireless sensors is one of bottle-neck problems.Based on piezoelectric effect,vibration energy can be harvested and converted into electricity.In recent years,piezoelectric vibration energy harvesting(PVEH)has become one kind of effective technologies to make low-power wireless sensor nodes self-powered.Most existing studies often assume that vibration sources have fixed positions,concentrated energies and single directions.For mechanical structures,however,vibration sources are often multi-directional and their energies often exist in the form of elastic waves with broadband and low-frequency characteristics.Therefore,how to combine specific characteristics of elastic waves with PVEH structures is an important application problem,which needs to be solved to improve harvesting efficiency of broadband and low frequency vibrations.Thus the topic of this paper will have important theoretical significance and application value.Under the support of the National Natural Science Foundation of China(Grant No.51577189),a piezoelectric metamaterial thin plate with local resonances is taken as a research object.Then an elastic wave propagation model in it is built based on basic theory of elastic wave propagation in thin plate and PVEH.Based on the model,the mechanisms of band-gap formation and vibration localization are studied.Also feedback influences of external load circuit are analyzed.Main works of this paper include:1.A model of the elastic wave propagation in locally resonant piezoelectric metamaterial was established.And the model was analyzed using Rayleigh-Ritz method and finite element method.Finally,the COMSOL finite element simulation software was used to get frequency response function of elastic waves propagating in the locally resonant piezoelectric metamaterial thin plate.2.Band-gap characteristics of locally resonant piezoelectric metamaterials were calculated by plane wave expansion method and finite element method respectively.The simulated modes were used to analyze the energy distribution in the cells during vibration.And finally,the influence of different material and structural parameters on the vibration band gap and energy localization was analyzed.The results can provide theoretical guidance for design optimization of locally resonant piezoelectric plate for broadband low frequency vibration energy harvesting.3.A systematic model of elasto-mechanical-electro coupling model of locally resonant piezoelectric metamaterials thin plate was established.Based on displacement transformation,the finite element method was used to analyze and calculate the model.And on this basis,the effects of different circuits on the band-gap structure was analyzed.4.Based on theoretical analysis,numerical calculation and finite element simulation,a locally resonant piezoelectric metamaterial thin plate was designed and fabricated.Then experiments are carried out to verify theoretical and simulated results. |
