【摘要】：隨著汽車工業(yè)的迅速發(fā)展,消費者對汽車的振動噪聲控制水平和整車舒適性的要求越來越高。同時,能源和環(huán)保問題也給汽車工業(yè)的發(fā)展帶來了挑戰(zhàn)。研宄表明,汽車整車質(zhì)量減輕,汽車的燃油經(jīng)濟性、操縱穩(wěn)定性、碰撞安全性等將會得到明顯的改善。所以,輕量化已經(jīng)成為現(xiàn)代汽車設計制造的一項重要目標。在結構表面粘貼粘彈性阻尼材料和附加動力吸振器是工程上常用的兩種被動減振降噪措施。具有高阻尼特性的粘彈性材料能在較寬的頻率范圍內(nèi)起到很好的減振降噪作用,被廣泛地應用在各個工業(yè)領域。由質(zhì)量塊、彈簧、阻尼材料構成的動力吸振器(DVA)發(fā)明至今已有一百多年的歷史,其結構簡單,制造成本低廉,可設計性較強,在工業(yè)減振降噪方面的作用越來越明顯。兩種減振降噪措施在實際應用中各有利弊,但每種方法均為原系統(tǒng)帶去了一定的附加質(zhì)量。本文的研究內(nèi)容重點在于比較在附加質(zhì)量一定的條件下,粘彈性阻尼材料和動力吸振器對結構的減振效果。研究目標旨在找到有利于實現(xiàn)輕量化目標的減振降噪方法。 本文以簡支梁的振動為研究對象,主要對比了自由阻尼層(ULD)、約束阻尼層(CLD)和動力吸振器(DVA)三種減振措施減振效果的好壞和附加質(zhì)量的大小。理論模型部分首先建立了簡支鋼梁上粘貼自由阻尼層結構(自由阻尼梁)和梁體附加動力吸振器結構(動力吸振器梁)振動響應的解析解力學模型,并在數(shù)值計算軟件MATLAB中編程求解得到了梁體結構在外界簡諧激振力下的穩(wěn)態(tài)位移、速度響應。此外,在有限元軟件MSC.NANSTRAN中建立了簡支鋼梁粘貼約束阻尼層結構(約束阻尼梁)的力學模型,在分析模塊中求解其頻率響應結果。并將計算得到的速度響應結果導入MATLAB計算軟件中與自由阻尼層和動力吸振器的減振方法做了對比分析。然后,通過實驗驗證了自由阻尼梁、約束阻尼梁和動力吸振器梁振動理論模型的正確性。自由阻尼層和約束阻尼層等粘彈性阻尼材料的減振性能主要由其力學參數(shù)決定,而粘彈性阻尼材料的力學參數(shù)又是隨出廠標準而定的,在實際工業(yè)應用并不能做參數(shù)優(yōu)化處理以達到更好的減振效果和更輕的附加質(zhì)量。通過優(yōu)化動力吸振器的質(zhì)量、剛度、阻尼比等重要參數(shù),可以使動力吸振器達到更好的減振效果,并為原系統(tǒng)帶去更小附加質(zhì)量。 本文設計了三組動力吸振器,一個質(zhì)量為10g旨在抑制簡支鋼梁第1階自然頻率處共振的單動力吸振器,每個質(zhì)量均為10g分別抑制簡支鋼梁第1階、第2階、第3階自然頻率下共振的三個動力吸振器以及每個質(zhì)量均為6g的三個動力吸振器,并將這三組動力吸振器的減振效果與自由阻尼層和約束阻尼層作了比較。其中,自由阻尼層重量為30g,約束阻尼層重量為18.4g。結果表明：約束阻尼層比自由阻尼層的減振效果更明顯,且附加質(zhì)量更輕,但后者制造成本較高。重為10g的單動力吸振器在簡支鋼梁第1階自然頻率處取得了比自由阻尼層和約束阻尼層更好的減振效果。通過對比還發(fā)現(xiàn),自由阻尼層在低頻范圍內(nèi)的減振效果不明顯,高頻減振效果突出,所以動力吸振器在簡支梁單模態(tài)和低頻范圍內(nèi)的減振應用方面更有優(yōu)勢,且附加質(zhì)量較輕。此外,三個重量均為6g動力吸振器在簡支梁前3階自然頻率處都起到了很好減振效果,且優(yōu)于兩種粘彈性阻尼材料。且隨著動力吸振器質(zhì)量的增加,三個重量為10g的動力吸振器的減振效果更為明顯,每個動力吸振器可控的振動頻帶更寬。綜合來看,動力吸振器對梁體振動的抑制作用更有針對性,且在較寬頻帶范圍內(nèi)的整體減振效果也十分理想,并能最大限度地減少在振動控制過程中帶來的附加質(zhì)量。
[Abstract]:With the rapid development of automotive industry, consumers are demanding higher and higher control level of vehicle vibration and noise and vehicle comfort. At the same time, energy and environmental protection problems also bring challenges to the development of automotive industry. Therefore, lightweight has become an important goal in the design and manufacture of modern automobiles. Viscoelastic damping materials and additional dynamic absorbers are two commonly used passive vibration and noise reduction measures in engineering. Noise reduction is widely used in various industrial fields. Dynamic vibration absorber (DVA) consisting of mass block, spring and damping material has been invented for more than one hundred years. It has simple structure, low manufacturing cost and strong designability. It plays a more and more important role in industrial vibration and noise reduction. Each method has its own advantages and disadvantages, but each method brings some additional mass to the original system. The main content of this paper is to compare the damping effect of viscoelastic damping material and dynamic absorber on the structure under the condition of certain additional mass.
In this paper, the vibration of a simply supported beam is taken as the research object, and the vibration reduction effect and additional mass of three vibration reduction measures, namely, free damping layer (ULD), constrained damping layer (CLD) and dynamic absorber (DVA), are compared. Analytical solution mechanics model of vibration response of vibration absorber structure (dynamic vibration absorber beam) is established, and steady displacement and velocity response of beam structure under external harmonic exciting force are obtained by programming in MATLAB. In addition, a simply supported steel beam with adhesive constrained damping layer structure (constrained damping beam) is established in the finite element software MSC.NANSTRAN. The results of the velocity response are imported into the MATLAB software and compared with the vibration reduction methods of the free damping layer and the dynamic vibration absorber. Then, the vibration theoretical models of the free damping beam, the constrained damping beam and the dynamic vibration absorber beam are verified by experiments. The damping performance of viscoelastic damping materials, such as free damping layer and constrained damping layer, is mainly determined by their mechanical parameters, while the mechanical parameters of viscoelastic damping materials are determined by factory standards. In practical industrial applications, it is impossible to optimize the parameters to achieve better damping effect and lighter additional mass. The mass, stiffness, damping ratio and other important parameters of the dynamic absorber can make the dynamic absorber achieve better damping effect and bring smaller additional mass to the original system.
In this paper, three groups of dynamic absorbers are designed. A single dynamic absorber with a mass of 10G is designed to suppress the resonance at the first natural frequency of a simply supported steel beam. Each mass of 10G is used to suppress the resonance at the first, second and third natural frequencies of a simply supported steel beam, and three dynamic absorbers with each mass of 6g. The damping effect of the three groups of dynamic absorbers is compared with that of the free damping layer and the constrained damping layer. The weight of the free damping layer is 30 g and the weight of the constrained damping layer is 18.4 g. The results show that the damping effect of the constrained damping layer is more obvious than that of the free damping layer, and the additional mass is lighter, but the manufacturing cost of the latter is higher. Compared with the free damping layer and the constrained damping layer, the free damping layer has not obvious damping effect in the low frequency range, and the high frequency damping effect is prominent. Therefore, the dynamic vibration absorber is applied in the single mode and low frequency range of the simply supported beam. In addition, the three 6 g dynamic absorbers have a good damping effect at the first three natural frequencies of the simply supported beam and are superior to the two viscoelastic damping materials. The controllable vibration frequency band of the vibrator is wider. Generally speaking, the dynamic vibration absorber has more pertinence to restrain the vibration of the beam, and the overall vibration reduction effect in a wider frequency band is also very ideal, and can minimize the additional mass in the vibration control process.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U465;TB535.1

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