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
Reducing the vibration transmission in beams is of significant interest,as beams are among the most widely used basic structures in numerous practical engineering applications.However,achieving broadband suppression o...Reducing the vibration transmission in beams is of significant interest,as beams are among the most widely used basic structures in numerous practical engineering applications.However,achieving broadband suppression of multi-polarization low-frequency vibration in beams presents a challenge.This study proposes a single-phase multi-resonant metabeam,which consists of a host beam with subwavelength arrays of tunable local resonators.These resonators exhibit adjustable multi-polarization resonant modes that strongly couple with the host beam,enabling simultaneous suppression of multi-type waves over a broad frequency range.The theoretical analysis demonstrates that under the fixed total added-mass ratio(γ_(total)=1.5),the tailored frequency spacing(δ=25-50 Hz)and the controlled loss factor(η=0.03–0.07)act synergistically to broaden bandgaps through resonant zone overlapping and attenuation peak smoothing.The experimental validation with monolithic three-dimensional(3D)-printed specimens confirms the efficacy of this design in multi-polarization vibration control within a deepsubwavelength bandgap,opening a new avenue for designing multi-polarization vibration suppression structures.展开更多
A novel elastic metamaterial is proposed with the aim of achieving lowfrequency broad bandgaps and bandgap regulation.The band structure of the proposed metamaterial is calculated based on the Floquet-Bloch theorem,an...A novel elastic metamaterial is proposed with the aim of achieving lowfrequency broad bandgaps and bandgap regulation.The band structure of the proposed metamaterial is calculated based on the Floquet-Bloch theorem,and the boundary modes of each bandgap are analyzed to understand the effects of each component of the unit cell on the bandgap formation.It is found that the metamaterials with a low elastic modulus of ligaments can generate flexural wave bandgaps below 300 Hz.Multi-frequency vibrations can be suppressed through the selective manipulation of bandgaps.The dual-graded design of metamaterials that can significantly improve the bandgap width is proposed based on parametric studies.A new way that can regulate the bandgap is revealed by studying the graded elastic modulus in the substrate.The results demonstrate that the nonlinear gradient of the elastic modulus in the substrate offers better bandgap performance.Based on these analyses,the proposed elastic metamaterials can pave the way for multi-frequency vibration control,low-frequency bandgap broadening,and bandgap tuning.展开更多
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。
基金Project supported by the National Natural Science Foundation of China(No.51875569)。
文摘Reducing the vibration transmission in beams is of significant interest,as beams are among the most widely used basic structures in numerous practical engineering applications.However,achieving broadband suppression of multi-polarization low-frequency vibration in beams presents a challenge.This study proposes a single-phase multi-resonant metabeam,which consists of a host beam with subwavelength arrays of tunable local resonators.These resonators exhibit adjustable multi-polarization resonant modes that strongly couple with the host beam,enabling simultaneous suppression of multi-type waves over a broad frequency range.The theoretical analysis demonstrates that under the fixed total added-mass ratio(γ_(total)=1.5),the tailored frequency spacing(δ=25-50 Hz)and the controlled loss factor(η=0.03–0.07)act synergistically to broaden bandgaps through resonant zone overlapping and attenuation peak smoothing.The experimental validation with monolithic three-dimensional(3D)-printed specimens confirms the efficacy of this design in multi-polarization vibration control within a deepsubwavelength bandgap,opening a new avenue for designing multi-polarization vibration suppression structures.
基金Project supported by the National Natural Science Foundation of China(Nos.11872233,U2341231,and 12102245)。
文摘A novel elastic metamaterial is proposed with the aim of achieving lowfrequency broad bandgaps and bandgap regulation.The band structure of the proposed metamaterial is calculated based on the Floquet-Bloch theorem,and the boundary modes of each bandgap are analyzed to understand the effects of each component of the unit cell on the bandgap formation.It is found that the metamaterials with a low elastic modulus of ligaments can generate flexural wave bandgaps below 300 Hz.Multi-frequency vibrations can be suppressed through the selective manipulation of bandgaps.The dual-graded design of metamaterials that can significantly improve the bandgap width is proposed based on parametric studies.A new way that can regulate the bandgap is revealed by studying the graded elastic modulus in the substrate.The results demonstrate that the nonlinear gradient of the elastic modulus in the substrate offers better bandgap performance.Based on these analyses,the proposed elastic metamaterials can pave the way for multi-frequency vibration control,low-frequency bandgap broadening,and bandgap tuning.
