Tuning Of Bandgaps In A Piezo Composite Phononic Beam Based On Shunting Circuit

Phononic crystals(PCs)is a kind of periodic structure in space arrangement.It is a novel acoustic functional structure which behaves band gaps in some specific frequency regions.With its mechanical-electric coupling effect,piezoelectric materials draw a lot of attention in recent years.Piezoelectric shunting circuit array is one important application of piezoelectric shunting damping technology in recent investigations,and piezoelectric shunting circuit is a practical technology in wave control.We combined piezoelectric shunting circuit and the concept of phononic crystals,then attached piezoelectric patches onto two sides of aluminum beam to satisfy the periodic structure as phononic crystals demand,and constructed a composite phononic crystal beam.In addition,shunting circuits are connected to piezoelectric patches,and by adjusting parameters in external circuits,we can actively control wave propagation in composite structures.This paper is mainly focused on elastic wave propagation in an aluminum beam periodically covered by piezoelectric patches.By theoretical derivation with Lyapunov exponent method,we obtained band gaps in these phononic crystal beam structures.Then we designed different types of external circuits,discussed positive and negative capacitance circuits to show the control effects on wave propagation.After that,we established a vibration testing platform to collect and analyze vibration testing signals in different external shunting circuits,and demonstrated active control action of negative capacitance circuit for wave propagation in the phononic crystal beam.With the FEM software COMSOL Multiphysics,we calculated wave propagation and attenuation in some designated frequencies and compared the situations with and without external circuits.Finally,we compared influences of several piezoelectric arrangements.The main contents and conclusions include:(1)Piezoelectric patches on one side can only produce stop bands with high frequencies and piezoelectric patches on two sides extend the stop bands,which produces some stop bands in lower frequency regions.Stop bands can be obtained broader when two-layer with the same length,and becomes narrower with different lengths.(2)If two-layer piezoelectric patches are arranged at the same side,in contrast to the situation that includes one-layer piezoelectric patches and one-layer aluminum patches,the difference of band gaps is not obvious.So,in this situation,we can only apply onelayer piezoelectric patches to adjust wave propagation and this way is more economic at the same time.(3)By external circuits,we discussed influences of positive and negative capacitance circuits on wave propagation.It can be concluded that the effect of the positive capacitance circuits is not significant but the negative capacitance circuits is different.By choosing the proper negative capacitance,we can adjust wave propagation in different frequency regions and achieve the propagation and gap regions.