| Composite vibration energy harvester has attracted the attention of researchers because of its advantages of simple structure,low cost,high specific strength,high specific stiffness and high energy collection efficiency,and has been applied to wireless sensor networks and small electronic devices.Three-dimensional braided composites is a kind of fiber reinforced composite,and its mechanical properties in all directions are relatively average.It is a new intelligent composites.In this article,three-dimensional braided composite materials with different braided angles and different volume fractions are used as the elastic layer of the energy collecting device,and a vibration energy harvester of three-dimensional braided piezoelectric composite material is innovatively proposed.The traditional piezoelectric composite vibration energy harvester generally exists in the form of laminated beam structure,which is prone to delamination fracture under low load impact,leading to the failure of vibration energy collecting device to achieve the best working state.In this article,three-dimensional braided composites material is used as elastic layer material of piezoelectric composite vibration energy collector.It is found that the device can improve the mechanical properties of the energy harvester and make the energy harvest efficiency reach the best.The main contents of this article are as follows:(1)According to three-dimensional four steps(1×1)braiding technology,harvester of 3-D braided piezoelectric composite vibration energy device of elastic material,the internal structure of 3-D braided composites fabrication fiber buckling shape and arrangement pattern has carried on the design and analysis,and through the three dimensional modeling software Solidworks completed the structure model of fiber yarns;On this basis,the elastic constitutive relation and force of mechanical properties of prefabricated parts are analyzed and the mechanical properties are analyzed.Based on the macroscopic model of materials,the representative volume element model of mesomechanics is established.The periodic boundary conditions of the representative volume element model were analyzed in detail and the finite element simulation software Abaqus was used to simulate the elastic constants of different three-dimensional braided composites.(2)The energy collector model of two piezoelectric vibration layers and three dimensional braided composite was established in series.Based on the constitutive equation of the structure and euler-Bernoulli beam theory,the vibration control equation is derived.For the displacement caused by structural vibration,the separation of variables is used to analyze it.Combining gauss current law in integral form and related circuit theory,the electromechanical coupling equation of vibration is derived.The vibration control equations under modal coordinates are obtained by converting concentrated excitation and distributed excitation.The analytical solution of output response of modal voltage is given.The comparison between numerical and simulated solutions is given.Studied under the different braiding Angle vibration energy collector’s output voltage and the output response to a single braid Angle of 3 d braided piezoelectric composite material under vibration energy collector voltage output response and power output response is given detailed simulation analysis and elaboration,and compared with straight fiber composite material the three-dimensional braided composite material as the advantage of the elastic layer.(3)Aiming at the deficiency of existing array vibration energy collector,a new model of staggered array vibration energy collector is proposed.According to Hamiltonian principle,the electromechanical coupling and vibration equations of staggered array vibration energy collecting device are derived.The theoretical output voltage of vibration energy collection devices with multiple array cell structures is derived from a single array cell structure. |
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