粘弹性材料阻尼性能评估系统的设计及复合阻尼结构阻尼特性的研究

发布时间：2018-03-23 17:00

  本文选题：振动噪声　切入点：阻尼测试　出处：《南京大学》2015年硕士论文

【摘要】：航空,汽车,舰船,建筑等领域普遍存在着振动与噪声,振动和噪声会加速机械结构的疲劳损坏,缩短机械设备使用寿命,影响人们工作生活环境的舒适度,长时间的振动噪声污染甚至伤害人体健康。粘弹性阻尼材料是一种重要的减振降噪材料,通常将其敷设在金属材料表面制备复合阻尼结构实现减振降噪的目的。粘弹性材料阻尼性能的表征方法很多,主要有强迫共振法和弯曲共振法,这两种方法能够准确的表征均匀材料本身的阻尼性能,但是复合阻尼结构的阻尼性能不仅与阻尼材料本身阻尼性能有关,还与结构有关。为此,本文建立了一套由材料本体、复合结构到模型的阻尼评估系统,此评估系统可通过动态力学性能测试指导阻尼材料的设计与优化,悬臂梁测试优化材料结构设计,振动测试检测材料结构频段内的减振效果,模态测试检测各阶共振频率的阻尼及振型。几种测试相互补充、前后呼应,可以完整的评估阻尼材料在减振降噪方面的作用。针对海洋、干湿交替以及强腐蚀场合等苛刻环境的特殊要求,设计了一种新型约束阻尼复合结构。约束阻尼复合结构的阻尼层以丁腈橡胶N21L为基材,添加不同形状的阻尼填料提高阻尼性能,其玻璃化转变温度在5℃左右,适宜作为水下阻尼材料。同时本文分析研究了填料的形状、粒径、用量对阻尼性能的影响,结果表明层状结构的云母粉能够显著提高材料的阻尼性能,云母粉的粒径在52μm时,用量在60 phr时,橡胶材料的阻尼性能最优。约束复合结构的约束层采用玻璃纤维增强树脂,避免了在海洋苛刻环境、干湿交替等条件下传统金属约束层材料的强腐蚀现象。玻璃纤维增强树脂材料作为约束层材料使复合阻尼结构的有效阻尼温度范围由25℃拓宽至55℃及以上。同时本论文通过悬臂梁弯曲共振法分析了自由阻尼与约束阻尼结构的阻尼特性,温度、阻尼层厚度以及空腔结构对约束复合结构阻尼减振效果的影响。结果表明：自由阻尼复合板的最大阻尼范围在阻尼层的玻璃化转变区；约束层能将复合结构的阻尼拓展至阻尼层的高弹态区域,增加阻尼层厚度可以提高约束复合板阻尼性能；提高孔隙率有利于提升约束复合板阻尼性能；铝板约束层提升作用尤为显著,然而海洋环境、干湿交替等强腐蚀场合,铝板极易腐蚀而丧失约束功能,在这类特殊场合耐腐蚀的玻璃钢则具优势。
[Abstract]:Vibration and noise are common in aviation, automobile, ship, building and so on. Vibration and noise will accelerate the fatigue damage of mechanical structure, shorten the service life of machinery and equipment, and affect the comfort of people's working and living environment. Long term vibration and noise pollution even harm to human health. Viscoelastic damping material is an important vibration and noise reduction materials, The damping properties of viscoelastic materials are characterized by forced resonance method and bending resonance method. These two methods can accurately characterize the damping properties of the homogeneous materials themselves, but the damping properties of the composite damping structures are not only related to the damping properties of the damping materials themselves, but also to the structure. The damping evaluation system from composite structure to model can be used to guide the design and optimization of damping material through dynamic mechanical performance test, cantilever beam test to optimize material structure design, vibration test to detect vibration absorption effect in the frequency band of material structure. Modal testing detects the damping and mode shapes of each order resonance frequency. Several kinds of tests complement each other and can be used to evaluate the effect of damping materials on vibration and noise reduction. In this paper, a new type of constrained damping composite structure is designed, which is based on nitrile rubber (N21L) as the damping layer. The glass transition temperature is about 5 鈩，

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