具有负泊松比特性的智能磁流变复合结构与减振降噪机理

The studies and designs of low vibration and noise material are the basic and crucial technique in noise controlling in the areas of industries and engineering, especially in the national defense equipments of noise controlling, as well as design of warship stealth, which has great significance and scientific value in the prevention of noise pollution and the security of national defense. It has always been the significant issue in researches on low vibration and noise material and the application in engineering to improve the performance of vibration and noise silencing in low frequency and widen its frequency band, as well as other comprehensive properties such as sound absorption and vibration suppression. This project creatively designs the magneorheological composite structure with negative poisson's ratio which can chang the properties as the powering frequency and have the excellent vibration and noise silencing. The composite structure can not only improve the performance of vibration and noise reducing in low frequency and broad frequency band, but also realize the good performance of sound absorption and vibration suppression. First, the magneorheological composite structure with negative poisson's ratio is prepared through special design. Then the magnetic circuit is optimally designed. Composite structure's attenuation performance on sound waves and vibrations with different frequencies in different magnetic fields is tested. And then the influence of magnetic fields' condition, structure and material's properties on the performance of sound absorption and vibration suppression is analyzed in experiment and theory, trying to find composite structure attenuation's basic law, basic cause and mechanism on sound waves and vibrations with different frequencies. Finally, a new theory about vibration and noise silencing of the magneorheological composite structure with negative poisson's ratio is proposed, which can provide the experimental and theoretical basis for designing and improving materials' performance on vibration and noise reducing in different application fields. It has important scientific significance and application value.

减振降噪材料的研究和设计是工业及工程噪声控制，特别是国防装备噪声控制及舰船隐身性设计的基础性与关键性技术。设法提高材料的低频减振降噪性能，拓宽材料的减振降噪频带，并同时兼顾吸声和抑制振动等综合性能，一直是减振降噪材料研究和工程应用中的重要课题。本项目创造性地将磁流变弹性体设计成具有负泊松比效应的复合结构，利用磁流变弹性体材料的智能可控特性和负泊松比材料对声振的高效吸收作用，不仅可以提高低频减振降噪性能，拓宽减振降噪频带，而且能够同时实现优良吸声和抑制振动性能，从而提高材料在宽频带范围内的减振降噪性能。首先制备负泊松比磁流变复合结构，并测试其性能，从试验和理论上研究其在不同频率下的声波和振动衰减的规律、根本原因和机理，提出负泊松比磁流变弹性体复合材料减振降噪的新理论，从而为设计和改进不同应用领域的高性能减振降噪材料提供理论依据，具有重要的科学意义和应用指导价值。

设法提高减振降噪材料的低频减振降噪性能，拓宽材料的减振降噪频带，并同时兼顾吸声和抑制振动等综合性能，一直是减振降噪材料研究和工程应用中的重要课题。.本研究采用特制模具将聚四氟乙烯磁流变材料进行拉伸固化成型制备出具有负泊松比效应的磁流变复合材料及其复合结构，并对其物理力学性能、磁致力学性能、本构模型、吸声性能及结构损耗因子进行了系统的研究，研究结果表明：研制的负泊松比磁流变复合材料及其复合结构具有优异的吸声性能和减振性能。具体结果如下：.（1）负泊松比磁流变复合材料泊松比随着电流的增大而增大，负泊松比效应减小；.（2）负泊松比磁流变复合材料动态力学模量和阻尼损耗因子随着电流的增大而增大。损耗因子随着控制电流的增大而增大的特性解决了具有正泊松比特性的磁流变复合材料阻尼性能不随控制电流增加而增大的技术难题；.（3）负泊松比磁流变复合材料声速和声衰减因子随着电流的增大而增大；.（4）负泊松比磁流变复合材料及其复合结构吸声性能随着电流的增大而增大，该特性可以解决传统吸声材料在低频下吸声系数较小，吸声频带较窄的技术难题，对设计新型吸声材料和结构具有重要的科学意义；.（5）负泊松比磁流变复合材料及其复合结构吸声性能随温度升高，低频下吸声系数减小，高频基本不变；.（6）负泊松比磁流变复合材料及其复合结构吸声性能随压力变化基本不变；.（7）负泊松比磁流变复合结构减振降噪机理为：一方面负泊松比磁流变复合结构能根据外界不同激励来实时改变材料性能参数，使其在较宽的频带内表面声阻抗与外界声阻抗相匹配，有利于更多的声能进入材料内部，与此同时，利用负泊松比磁流变复合材料本身优异的声衰减能力及其复合结构对声波的多次反射、多次吸收作用，将更多的声能转化为热能消耗掉，从而实现较宽频带内的优良吸声性能；另一方面，负泊松比磁流变复合结构具有较高的结构损耗因子，能够将更多的振动能量转化为热能消耗掉，从而具有优异的抑制振动性能。