Vibration Reduction And Sound Insulation Characteristics Of Acoustic Metamaterial Based Ultra-light Cellular Sandwich Structures

Ultra-light cellular sandwich structures have broad application prospects in the field of aerospace equipment,transportation,national defense industry and so on,due to their excellent mechanical properties,such as high specific stiffness,large specific strength,strong toughness and collision resistance,etc.However,because of such structures' light-weight and low damping,they are easy to generate and transmit low-frequency vibration and noise.Consequently,carrying out such structures' low frequency vibration and noise reduction design is of great engineering and theoretical significance.Acoustic metamaterial possesses the characteristics of low frequency band gap,which can suppress the propagation of elastic waves,providing a new idea for structure vibration and noise control.In this paper,the concept of acoustic metamaterial is introduced into ultra-light cellular sandwich structures to construct acoustic metamaterial bsed ultra-light cellular sandwich structures,and the low-frequency band gap characteristics as well as vibration reduction and sound insulation characteristics of the constructed new structures are investigated.The main research work and conclusions are as follows:1.A Bloch wave based semi-analytical method for dynamic homogenization of ultra-light cellular sandwich structures is proposed,which realizes high-efficiency predition of the acoustic/vibration characteristic of such structures.The proposed method provides much higher accuracy of acoustic/vibration characteristics prediction,and is applicable for more conditions compared with a representative method existing in the literature.The work establishes important methodlogical basis of acoustic/vibration characterisitics analysis and noise/vibration reduction design of ultra-light cellular sandwich structures.2.The band gap and vibration reduction characteristics of acoustic metamaterial based ultra-light cellular sandwich structures are studied in depth.The high efficiency model for calculating the band gap and vibration characteristic of acoustic metamaterial based ultra-light cellular sandwich structures is built.And the influence of the key parameters including stiffness,additional mass ratio,lattice constant,and natural frequency of the resonators are systematically analyzed,and the influence regulation of the parameters are detected.3.The sound insulation characteristics of coustic metamaterial based ultra-light cellular sandwich structures are studied in depth.The study manifests that,when the natural frequency of the resonators is tuned to the low frequency mass law region,the structures can bring about sound insulation peak at the natural frequency of the resonators,which will significantly improve the sound insulation performance of the structure and break the limitation of the mass law;When the natural frequency of the resonators is tuned to the mid-high frequency coincidence region,the sound insulation performance will be greatly improved in a wide frequency range around the resonators' natural frequency,which can effectively solve the problem of poor sound insulation performance of ultra-light cellular sandwich structures within coincidence region.4.The principle samples of acoustic metamaterial based ultra-light cellular sandwich structures are designed and constructed,whose vibration reduction and sound insulation characteristics are tested.The experimental results verify that the constructed structures can produce low frequency band gap,achieving extraordinary vibration reduction and sound insulation.In summary,this paper establishes an efficient modeling and analysis method for acoustic and vibration characteristics of ultra-light cellular sandwich structures,and systematically analyzes the band gap,vibration reduction and sound insulation characteristics of the acoustic metamaterial based ultra-light cellular sandwich structures in depth.The work provides new theoretical and technical support for low frequency vibration and sound reduction design of ultra-light celluar sandwich structures,and contributes to promote the development of multi-functional integrated structures.