Acoustics Black Holes(ABH)effects can be achieved through manipulations of bending wave propagation inside a thin-walled structure with its thickness tailored according to a power-law variation.In doing so,the phase v...Acoustics Black Holes(ABH)effects can be achieved through manipulations of bending wave propagation inside a thin-walled structure with its thickness tailored according to a power-law variation.In doing so,the phase velocity of the bending wave gradually reduces alongside thickness thinning,eventually to zero in the ideal scenario at the wedge tip/indentation center,resulting in zero wave reflection and high energy concentration within a small localized area.The phenomenon attracts increasing attentions as a promising passive vibration control method because vibration energy can be channeled and only a very small amount of damping material is required within the energy focalization region to achieve efficient damping to flexural waves.In addition,the wave slowing phenomenon allows the creation of a subsonic region inside a supersonic structure,thus reducing the its overall sound radiation efficiency.These unique features point at a great potential of the ABH technology for various applications such as vibration control,sound radiation reductions and energy harvesting.This talk summarizes some of the recent progress made in the study of the ABH.Topics cover the semi-analytical modelling of the ABH structures;design and analysis of a double-layer compound ABH beam for improved static and dynamic properties;combination of locally resonant and Bragg scattering for broadband stopband creation as well as some examples of ABH for vibration and sound noise control applications.展开更多
声学黑洞(acoustic black hole,ABH)效应是利用薄壁结构几何参数或者材料特性参数的梯度变化,使波在结构中的传播速度逐渐减小,理想情况下波速减小至零从而不发生反射的现象.实现声学黑洞效应的主要方法是将薄板结构的厚度按照一定规律...声学黑洞(acoustic black hole,ABH)效应是利用薄壁结构几何参数或者材料特性参数的梯度变化,使波在结构中的传播速度逐渐减小,理想情况下波速减小至零从而不发生反射的现象.实现声学黑洞效应的主要方法是将薄板结构的厚度按照一定规律裁剪,利用声学黑洞可以将结构中传播的波动能量聚集在特定的位置.声学黑洞对波的聚集具有宽频高效、实现方法简单灵活等特点,在薄壁结构的减振降噪、能量回收等应用中具有明显的优势.本文介绍声学黑洞效应的基本原理、相关力学问题的研究进展和有待进一步探究的问题,包括声学黑洞结构的建模与分析方法、实验研究方法及进展、声学黑洞结构中波的传播与操控,以及声学黑洞在工程应用中的相关问题.展开更多
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...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。展开更多
文摘Acoustics Black Holes(ABH)effects can be achieved through manipulations of bending wave propagation inside a thin-walled structure with its thickness tailored according to a power-law variation.In doing so,the phase velocity of the bending wave gradually reduces alongside thickness thinning,eventually to zero in the ideal scenario at the wedge tip/indentation center,resulting in zero wave reflection and high energy concentration within a small localized area.The phenomenon attracts increasing attentions as a promising passive vibration control method because vibration energy can be channeled and only a very small amount of damping material is required within the energy focalization region to achieve efficient damping to flexural waves.In addition,the wave slowing phenomenon allows the creation of a subsonic region inside a supersonic structure,thus reducing the its overall sound radiation efficiency.These unique features point at a great potential of the ABH technology for various applications such as vibration control,sound radiation reductions and energy harvesting.This talk summarizes some of the recent progress made in the study of the ABH.Topics cover the semi-analytical modelling of the ABH structures;design and analysis of a double-layer compound ABH beam for improved static and dynamic properties;combination of locally resonant and Bragg scattering for broadband stopband creation as well as some examples of ABH for vibration and sound noise control applications.
文摘声学黑洞(acoustic black hole,ABH)效应是利用薄壁结构几何参数或者材料特性参数的梯度变化,使波在结构中的传播速度逐渐减小,理想情况下波速减小至零从而不发生反射的现象.实现声学黑洞效应的主要方法是将薄板结构的厚度按照一定规律裁剪,利用声学黑洞可以将结构中传播的波动能量聚集在特定的位置.声学黑洞对波的聚集具有宽频高效、实现方法简单灵活等特点,在薄壁结构的减振降噪、能量回收等应用中具有明显的优势.本文介绍声学黑洞效应的基本原理、相关力学问题的研究进展和有待进一步探究的问题,包括声学黑洞结构的建模与分析方法、实验研究方法及进展、声学黑洞结构中波的传播与操控,以及声学黑洞在工程应用中的相关问题.
文摘声学黑洞(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。
