Abstract: Aiming at the nonlinear PIO problem caused by Aero-engine noise during ultra-low-altitude airdrop process, a circular membrane-ring structure mode local resonance mechanism resonators was applied to reduce noise and vibration. The analysis of band gap formation mechanisms , the width of band gap affect factors, and sound insulation quantities by theoretical analysis and simulation test. The simulation test results show that the locally resonant band gap is the consequence of the local resonances and the traveling wave modes interactions. The coupling strength affect bandwidth and sound insulation effect directly,which depends on thin membrane size and surface density, so the greater the radius of inner and the surface density, the wider band-gap, the higher the resonant frequency; sound Insulation depends on the thin membrane surface density,the circular surface density and the position of center ring. This research result that the structure has a good sound insulation of characteristics by optimizing structure parameters, which suppress vibration and improve flying qualities of transport effectively.

Key words: local resonance;band-gap mechanism;width band gap;sound insulation characteristic