本文選題：振動噪聲　切入點：阻尼測試　出處：《南京大學》2015年碩士論文

【摘要】：航空,汽車,艦船,建筑等領域普遍存在著振動與噪聲,振動和噪聲會加速機械結構的疲勞損壞,縮短機械設備使用壽命,影響人們工作生活環(huán)境的舒適度,長時間的振動噪聲污染甚至傷害人體健康。粘彈性阻尼材料是一種重要的減振降噪材料,通常將其敷設在金屬材料表面制備復合阻尼結構實現(xiàn)減振降噪的目的。粘彈性材料阻尼性能的表征方法很多,主要有強迫共振法和彎曲共振法,這兩種方法能夠準確的表征均勻材料本身的阻尼性能,但是復合阻尼結構的阻尼性能不僅與阻尼材料本身阻尼性能有關,還與結構有關。為此,本文建立了一套由材料本體、復合結構到模型的阻尼評估系統(tǒng),此評估系統(tǒng)可通過動態(tài)力學性能測試指導阻尼材料的設計與優(yōu)化,懸臂梁測試優(yōu)化材料結構設計,振動測試檢測材料結構頻段內的減振效果,模態(tài)測試檢測各階共振頻率的阻尼及振型。幾種測試相互補充、前后呼應,可以完整的評估阻尼材料在減振降噪方面的作用。針對海洋、干濕交替以及強腐蝕場合等苛刻環(huán)境的特殊要求,設計了一種新型約束阻尼復合結構。約束阻尼復合結構的阻尼層以丁腈橡膠N21L為基材,添加不同形狀的阻尼填料提高阻尼性能,其玻璃化轉變溫度在5℃左右,適宜作為水下阻尼材料。同時本文分析研究了填料的形狀、粒徑、用量對阻尼性能的影響,結果表明層狀結構的云母粉能夠顯著提高材料的阻尼性能,云母粉的粒徑在52μm時,用量在60 phr時,橡膠材料的阻尼性能最優(yōu)。約束復合結構的約束層采用玻璃纖維增強樹脂,避免了在海洋苛刻環(huán)境、干濕交替等條件下傳統(tǒng)金屬約束層材料的強腐蝕現(xiàn)象。玻璃纖維增強樹脂材料作為約束層材料使復合阻尼結構的有效阻尼溫度范圍由25℃拓寬至55℃及以上。同時本論文通過懸臂梁彎曲共振法分析了自由阻尼與約束阻尼結構的阻尼特性,溫度、阻尼層厚度以及空腔結構對約束復合結構阻尼減振效果的影響。結果表明：自由阻尼復合板的最大阻尼范圍在阻尼層的玻璃化轉變區(qū)；約束層能將復合結構的阻尼拓展至阻尼層的高彈態(tài)區(qū)域,增加阻尼層厚度可以提高約束復合板阻尼性能；提高孔隙率有利于提升約束復合板阻尼性能；鋁板約束層提升作用尤為顯著,然而海洋環(huán)境、干濕交替等強腐蝕場合,鋁板極易腐蝕而喪失約束功能,在這類特殊場合耐腐蝕的玻璃鋼則具優(yōu)勢。
[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，

本文編號：1654354