Energy focusing effect of two-dimensional acoustic black hole on flexural waves

Abstract

声学黑洞(Acoustic Black Holes,ABH)效应是利用结构厚度以一定幂函数形式减小,致使弯曲波的相速度逐渐减小而实现能量逐渐聚集,理想情况下弯曲波波速减小为0从而无法传递到结构边缘,也就不会发生反射。声学黑洞效应使得结构产生高能量密度区域,因此能高效应用于能量回收和振动噪声控制。为了研究二维声学黑洞结构具有弯曲波能量聚集效应,运用有限元分析软件ABAQUS建立了二维声学黑洞模型,从时域上研究弯曲波在声学黑洞区域的传播过程,结合有限元数值结果与振动功率流的结果分析弯曲波能量聚集过程。最后通过激光超声实验系统对二维声学黑洞中弯曲波传播过程进行成像与分析,实验结果验证了二维声学黑洞结构对弯曲波能量的聚集效应。 The acoustic black hole (ABH) phenomenon in thin-walled structures with a power function form reducing leads to a smooth reduction of the phase velocity of flexural waves and energy focalization. In an ideal case, flexural wave velocity decreases to zero so that it never reaches a structure's edge, much less reflects back. This causes structural areas with high energy density, the high energy effects can be used for various engineering applications, such as, energy harvesting, vibration and noise control and so on. In order to investigate the energy focusing effect of two-dimensional acoustic black hole on flexural waves, the model of two-dimensional acoustic black hole was built using the finite element software ABAQUS, and numerical simulations were conducted for the transmission of flexural wave in the acoustic black hole areas. Vibration power flow and finite element simulation were combined to analyze the energy focalization of flexural waves. Finally, the transmission process of flexural wave in two-dimensional acoustic black hole was imaged and analyzed by using the laser ultrasonic scanning technique. The test results verified the energy focalization effect of two-dimensional acoustic black hole on flexural waves.