A flexible foam-filled honeycomb constrained damping sandwich structure and its preparation method

Abstract

A flexible foam-filled honeycomb constrained damping sandwich structure sequentially includes a constrained damping layer 1, a sound-insulating layer 2, a sound-absorbing layer 3, a sound-insulating layer 4, and a constrained damping layer 5 from bottom to top, wherein the constrained damping layer 1 and the constrained damping layer 5 It is the damping rubber of adhesive film material, the sound-insulating layer 2 and the sound-insulating layer 4 are hard fiberboards, and the sound-absorbing layer 3 is a flexible foam-filled honeycomb; the present invention is a sandwich structure integrating sound-absorbing, sound-insulating, damping and shock-absorbing, The sound insulation and shock absorption performance of the product is improved, the sound insulation and sound absorption effect is good, the sound insulation volume can be as high as 51.2dB, the sandwich structure is strong, easy to process and shape, the preparation method is simple and feasible, and it is worthy of market promotion and application.

Description

technical field [0001] The invention relates to the technical field of composite materials, in particular to a flexible foam-filled honeycomb constrained damping sandwich structure and a preparation method thereof. Background technique [0002] Under the condition of steady flight of civil helicopters, the noise pollution inside the cockpit is serious, and the total sound pressure level of the cabin noise reaches 90dB-120dB. Strong noise not only seriously endangers the hearing system of pilots and combatants, but also endangers the health of passengers. Moreover, long-term work in a strong noise environment is likely to cause fatigue, reduce the pilot's attention, and greatly increase the possibility of inducing dangerous accidents. [0003] Helicopter noise sources mainly come from rotors, tail rotors, engines, and transmission systems. The above-mentioned systems and components have adopted noise reduction designs to control the sound source. However, due to the limitatio...

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Problems solved by technology

Strong noise not only seriously endangers the hearing system of pilots and combatants, but also endangers the health of passengers. Moreover, working in a strong noise environment for a long time can easily cause fatigue, reduce the pilot's attention, and greatly increase the possibility of inducing dangerous accidents.

[0003] Helicopter noise sources mainly come from rotors, tail rotors, engines, and transmission systems. The above-mentioned systems and components have adopted noise reduction designs to control the sound source. However, due to the limitation of processing and assembly accuracy, rotors and transmission systems are still the main sources The noise source in the cabin still exceeds the specified noise limit, and noise reduction measures need to be taken on the noise transmission path

Helicopters use a large number of hard fiberboard / honeycomb composite sandwich structures. The honeycomb can effectively absorb external shocks and convert them into deformation energy of the core material, and then release them slowly. In addition, when sound waves enter the honeycomb body, it will cause vibrations in the air and materials. Frictional resistance and viscous resistance convert part of the sound energy into heat energy and dissipate it, which has a certain noise reduction effect, but the sound pressure level in the high-frequency range of 1000Hz to 3000Hz in the cabin still exceeds the maximum design limit of the helicopter, and the noise reduction and shock absorption effects Not ideal, still unable to meet the needs of noise reduction in the helicopter cabin

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