外文翻譯--研究汽車盤式制動器熱和力學(xué)性能的優(yōu)化設(shè)計

1、<p>　　研究汽車盤式制動器熱和力學(xué)性能的優(yōu)化設(shè)計 </p><p>　　摘要: 運用ABAQUS軟件,對轎車盤式制動器在不同車速、不同摩擦片材料下的模擬仿真,</p><p>　　據(jù)不同工況下的計算結(jié)果得出磨擦片熱分布規(guī)律,最后提出盤式制動器的改進設(shè)計方案。</p><p>　　關(guān)鍵詞:盤式制動器;摩擦熱;有限單元 </p><p&

2、gt;　　制動系統(tǒng)是汽車最重要的系統(tǒng)。如果制動失敗,結(jié)果是很可怕的。制動系統(tǒng)實際上是能量轉(zhuǎn)換裝置,將汽車的動能轉(zhuǎn)換為熱能。典型的制動系統(tǒng)包括盤式制動器和鼓式制動器。</p><p>　　汽車上使用的是兩個完整的獨立的制動系統(tǒng)。他們是行車制動和駐車制動。行車制動在減速，停車或正常行駛時駐車起作用。他們通過司機踩踏和放松制動踏板來實現(xiàn)。制動器的主要目的是在無人看管是保持車輛平穩(wěn)停止。駐車制動是在拉起手剎或制動腳踏板時

3、由機械操縱的。 </p><p>　　盤式制動器因為產(chǎn)生的熱和停車時的機械載荷很容易引起噪聲和震動問題。這種噪音,震動和NVH現(xiàn)象不僅不舒服，而且很危險。此外，由于熱摩擦產(chǎn)生的溫度變化，導(dǎo)致制動盤和轉(zhuǎn)子之間摩擦轉(zhuǎn)變和墊襯材料機械壓力系數(shù)變化。壓力變化是一種非線性現(xiàn)象，正如摩擦現(xiàn)象是一般非線性耦合問題。特別是在汽車盤式制動系統(tǒng)中熱抖動噪聲振動是非線性耦合問題。這些現(xiàn)象也共享核心設(shè)計等因素,如轉(zhuǎn)子和襯里之間的壓力分布

4、，轉(zhuǎn)子的形狀和剛度,空氣排氣口組成，散熱的性能和摩擦的變化。因此，應(yīng)在考慮和分析抖動和噪聲的同時優(yōu)化盤式制動器的設(shè)計。</p><p>　　當(dāng)出現(xiàn)嚴重的摩擦加熱超過一定的轉(zhuǎn)子和墊之間的滑動速度，臨界速度時，會發(fā)生熱彈性形變。一些關(guān)鍵的因素，如臨界速度，外部溫度，運動時閥板厚度變化可能會導(dǎo)致制動盤的熱變形。此外,頻繁制動也能誘導(dǎo)制動器的高熱。這些情況導(dǎo)致較高的熱變形和熱點，這是熱顫動的原因之一。一個相對高強度，低頻

5、率的震動，應(yīng)該是從盤式制動系統(tǒng)通過樞紐，懸浮驅(qū)動，方向盤，剎車踏板和地板。此外，頻繁和高溫?zé)狳c結(jié)合，很容易導(dǎo)致物質(zhì)損失，其中包括制動盤表面裂紋的產(chǎn)生。該熱點現(xiàn)象也稱為摩擦性熱彈性不穩(wěn)定，被Barber首次發(fā)現(xiàn)并應(yīng)用到摩擦系統(tǒng)。Lee和Barber解決了假設(shè)隨著時間推移，在溫度和應(yīng)力場的擾動成倍增加的TEI 問題。他們表明，不穩(wěn)定的發(fā)病總是由一個反對稱的對應(yīng)圓周屈曲變形模式導(dǎo)致熱點在制動盤兩側(cè)交替。此外，使用汽車盤式模型，他們發(fā)現(xiàn)，由兩個

6、半空間模型計算的臨街轉(zhuǎn)速高出實驗。Yeo和Barber衍生出的有限元攝動方法，即線性方程組是利用時間獲取與指數(shù)變化擾動分隔的變量的解決方案制定。他們利用有限元分析解決了盤式制動器和離合器的TEI問題。他們解釋說，主波長和臨界速度并非主要受三維效果的影響，被很好的預(yù)測一個二維（平面）的</p><p>　　盡管努力減少或消除噪聲的發(fā)生，噪聲呈現(xiàn)出另一種整個汽車行業(yè)的主要制動器的NVH問題。這是一種當(dāng)司機減速或低速是

7、產(chǎn)生的高頻率的噪聲。因為他是耦合的制動系統(tǒng)，噪聲不容易解決。因此，噪聲問題應(yīng)該仔細評估。有兩種利用有限元分析的方法來模擬和分析盤式制動器的噪聲問題，一是非線性瞬態(tài)模擬或動態(tài)瞬態(tài)分析，另一種是線性或非線性穩(wěn)定分析。這兩種方法各有優(yōu)缺點，要準(zhǔn)確的分析和預(yù)測噪聲，都需要在轉(zhuǎn)子和其他制動元件固有特性研究方面有良好的相關(guān)性。目前有很多以通過實驗方法和仿真的研究。Dessouki等把噪聲分為卡鉗托架誘導(dǎo)（2-6.5千赫），墊誘導(dǎo)（4-11千赫）和轉(zhuǎn)

8、子誘導(dǎo)（7-16千赫）幾類。通過FEA，Junior等研究了某些操作參數(shù)如摩擦系數(shù)，材料性能，磨損以及絕緣體對盤式制動系統(tǒng)的影響。Fieldhouse根據(jù)一些具體的噪聲頻率研究了墊的形狀，并解釋說動態(tài)的不穩(wěn)定行能被預(yù)測。Kung等使用復(fù)雜的特征值問題的方法研究了低頻噪聲，并報告說這是種有效的分析方法。Dihau和Jiang利用有限元分析研究耦合模式解決了復(fù)雜的特征值問題。Triches等采用模態(tài)分析技術(shù)選擇適當(dāng)?shù)闹苿娱l以減少剎車噪聲。

9、Kung等</p><p>　　在這項研究中，通過三個轉(zhuǎn)子標(biāo)本對TEI和機械穩(wěn)定性進行了研究。制動測功機和高速紅外攝像機被用于TEI分析。圓錐角是根據(jù)制動盤的形狀確定，角度的改變能改變制動盤和墊之間的接觸壓力分布，是改變壓力分布的主要因素。壓力分布影響著熱穩(wěn)定性和機械穩(wěn)定性。首先，熱變形和圓錐角的在恒定溫度下的變化是計算所考慮的幾何轉(zhuǎn)子。焊盤的壓力分布按照卡尺增壓類型計算，并將結(jié)果和TEI進行分析和比較。臨界轉(zhuǎn)速

10、的分析結(jié)果通過商業(yè)軟件HOTSPOTTER獲得。將從實驗和分析方法得到的結(jié)果進行比較和分析。要進行復(fù)雜的特征值分析，自然頻率和模式是由制動盤和墊片的模態(tài)試驗和有限元分析得出的。通過有限元分析，按照制動盤厚度，襯砌弧長度和增壓類型來決定不穩(wěn)定耦合模式并估計不穩(wěn)定的機械力學(xué)性能差異來解決復(fù)雜的特征值問題。最后，利用這些成果為優(yōu)化熱性能和力學(xué)性能進行評估和分析。</p><p>　　盤式制動器轉(zhuǎn)子部分由頂部，頸部，氣孔

11、和內(nèi)外側(cè)板組成。摩擦熱被認為是轉(zhuǎn)子的主要熱源，其產(chǎn)生是由于內(nèi)外側(cè)板和剎車片之間的接觸摩擦。如熱傳導(dǎo)，熱對流過程，和輻射產(chǎn)生的轉(zhuǎn)子溫度梯度，并導(dǎo)致熱變形。此外，內(nèi)外側(cè)的密度層不僅在接觸表面的局部熱集中，由于密度方向傳到速度的差異，還影響轉(zhuǎn)子剛度，特別是在外平面。這三個幾何模型是基本模型，2t-0t模型和2t-2t模型。所有這3個轉(zhuǎn)子直徑均為254毫米。在2t-0t轉(zhuǎn)子模型中，外側(cè)的鋼板厚度減少了2毫米。類似的，在2t-2t轉(zhuǎn)子模型中，內(nèi)側(cè)

12、和外側(cè)的鋼板厚度均減少了2毫米。</p><p>　　轉(zhuǎn)子的熱變形是由于摩擦生熱產(chǎn)生的制動盤和焊盤之間的非均勻壓力分布。轉(zhuǎn)子之間的接觸壓力和高墊影響TEI和機械不穩(wěn)定性。摩擦熱源是法向力，摩擦系數(shù)和相對速度的一個表現(xiàn)。制動盤和墊之間眼里分布產(chǎn)生的偏心是由于錐角偏轉(zhuǎn)，DTV和加壓性卡鉗及可能導(dǎo)致的快速非均勻發(fā)熱。在這些因素中，可以對轉(zhuǎn)子的形狀設(shè)計適當(dāng)降低圓錐角。對此進行熱變形和壓力分布的有限元分析。</p&g

13、t;<p>　　圓錐角沒有固定值由于在行駛時轉(zhuǎn)子的溫度分布變化。通常，通過實驗和有限元分析調(diào)節(jié)制動工況來實現(xiàn)圓錐角，熱應(yīng)力和熱容量。然而，在這項研究中，為了通過轉(zhuǎn)子厚度有限元分析來尋找相應(yīng)的圓錐角假定了一個均勻100°C的溫度。通過仿真結(jié)果，對熱性能進行評價并按照內(nèi)外側(cè)的厚度差別進行分析。根據(jù)TEI和按照墊形狀和增壓條件的機械不穩(wěn)定性對壓力分布進行非線性有限元分析。為了產(chǎn)生一個墊上對應(yīng)一點到兩點加壓卡鉗的壓力分布

14、，應(yīng)用一個反映卡鉗活塞形狀的壓力條件。靜態(tài)和動態(tài)條件下都適用。在靜態(tài)條件下，旋轉(zhuǎn)速度為零，靜壓力為1.5MPa。在動態(tài)條件下，轉(zhuǎn)子轉(zhuǎn)速為10轉(zhuǎn)/分，壓力大小為1.5MPa，摩擦系數(shù)為0.4。在TEI分析，該墊的壓力分布可用于預(yù)測有效壓力和有效內(nèi)襯弧長，它反映了熱點數(shù)目和臨界速度。熱點數(shù)目和臨界速度與內(nèi)襯弧長密切相關(guān)。因此，利用有效壓力和有效內(nèi)襯弧長的概念可以使TEI模型更加準(zhǔn)確。使用有限元分析套件ABAQUS 6.6對熱變形和結(jié)構(gòu)分析來

15、計算出圓錐角和壓力分布。</p><p>　　圓錐角是根據(jù)制動盤厚度并通過對熱結(jié)構(gòu)有限元分析來計算的。模擬結(jié)果顯示了再100°C時圓錐角和內(nèi)測板的偏轉(zhuǎn)。圓錐角的相對比率是轉(zhuǎn)子標(biāo)準(zhǔn)錐角和基準(zhǔn)的比。結(jié)果表明，圓錐角有一個相對較低的絕對值。然而，由于恒定溫度邊界條件需要根據(jù)轉(zhuǎn)子形狀實現(xiàn)一個相對熱變形差，所以相對圓錐角差值比絕對圓錐角更重要。根據(jù)轉(zhuǎn)子的基本標(biāo)準(zhǔn)，2t-0t模型顯示了最小的圓錐角比例。這一結(jié)果表明

16、，頸部的截面差異很大的作用于導(dǎo)致變形差的幾何約束。因此，內(nèi)外側(cè)厚度差異不僅顯著的影響結(jié)構(gòu)特征，而且引起熱變形。在實際的汽車上，在嚴重的熱負荷和機械負荷下，轉(zhuǎn)子邊緣的撓度與由于DTV和跳動產(chǎn)生的非均勻壓力下相比相對值較高。因此，它不能夠被忽視。雖然DTV和跳動還增加了制動盤和焊盤之間的局部壓力，他們不依賴與轉(zhuǎn)子橫截面的形狀。因此，為了制動盤的優(yōu)化設(shè)計考慮熱變形和轉(zhuǎn)子錐角以及熱容量是必要的。</p><p>　　熱

17、力耦合和熱抖動過程造成制動盤表面產(chǎn)生熱點，不穩(wěn)定的摩擦生熱，熱彈性形變和彈性接觸。總所周知，首先，司機會感到如方向盤，踏板的抖動，在較高頻率內(nèi)伴隨著震動聲音。然后，制動抖動主要影響舒適性，或有可能當(dāng)一個沒有經(jīng)驗的司機第一次面對時導(dǎo)致了錯誤的反應(yīng)會影響行車安全，最后，熱抖動會造成制動盤永久性的扭曲或開裂。高溫也可能導(dǎo)致剎車過度磨損，尤其是在出現(xiàn)熱點的位置。實驗技術(shù)在熱力耦合調(diào)查中發(fā)揮主要作用。在捷克克大學(xué)最新技術(shù)研究中心，Pilsen，對

18、在實驗室和實際情況下的熱力耦合進行實驗研究。其目的是弄清各種物理參數(shù)的影響，包括起源，發(fā)展和熱力耦合在宏觀和微觀的后果。其結(jié)果將被應(yīng)用到設(shè)計人員的結(jié)構(gòu)建議中，并轉(zhuǎn)化為對制動系統(tǒng)和技術(shù)用戶的技術(shù)建議。 </p><p>　　A study of thermal and mechanical behaviour for the optimal design of automotive disc brakes <

19、/p><p>　　Abstract:With finite element analys is software ABAQUS , the work statements of car disk brake in different speeds and different materials are analysis . Then according to the results of heat is tribut

20、ions in the different statements , the rules of heat distributions are given . Finally , improvement methods about designing disk brake are presented.</p><p>　　Keywords : Disk brake ; Friction heat ;Finite e

21、lement method</p><p>　　The braking system is the most important system in cars. If the brakes fail, the result can be disastrous. Brakes are actually energy conversion devices, which convert the kinetic ener

22、gy (momentum) of the vehicle into thermal energy (heat). The typical brake system consists of disk brakes in front and either disk or drum brakes.</p><p>　　Two complete independent braking systems are used o

23、n the car. They are the service brake and the parking brake. The service brake acts to slow, stop, or hold the vehicle during normal driving. They are foot-operated by the driver depressing and releasing the brake pedal.

24、 The primary purpose of the brake is to hold the vehicle stationary while it is unattended. The parking brake is mechanically operated by when a separate parking brake foot pedal or hand lever is set.</p><p>

25、;　　Disc brake systems are prone to noise and vibration problems arising because of the severe thermal and mechanical loads applied to stop the vehicle. This noise, vibration, and harshness (NVH) phenomenon is not only un

26、comfortable but also dangerous. In addition thermal variations, which occur by frictional heat, generate mechanical pressure variation between the disc and lining owing to a change in the friction coefficient between the

27、 rotor and pad lining materials. The pressure variation is a no</p><p>　　When severe friction heating occurs over a certain sliding speed (critical speed) between the rotor and pad, thermoelastic distortion

28、occurs. Some critical factors such as the critical speed, external temperature, run-out, and disc thickness variation (DTV) can cause thermal distortion of the brake disc. In addition, frequent braking also induces high

29、thermal deformation in the brake disc. These conditions cause relatively high thermal distortion and hot spots, which are one of the origins of h</p><p>　　Despite efforts to reduce or eliminate its occurren

30、ce, squeal noise presents another major brake NVH problem throughout the automotive industry .It is a high-frequency noise produced when the driver decelerates and/or stops the vehicle at a low speed. Because it is coup

31、led to the brake system, squeal cannot be solved easily. Therefore, the squeal problem should be evaluated carefully. There are two main approaches to simulate and analyse disc brake squeal using FEA methods: one is non

32、-linear t</p><p>　　In this study, TEI and mechanical instability are investigated in accordance with three rotor specimens: lining arc lengths of one-pot pressurization and two-caliper pressurization types (

33、one-pot and two-pot types). A brake dynamometer and a high-speed infrared camera are used for the TEI analysis. The coning angle is formed in accordance with brake disc shapes such as hat and neck, and this angle alters

34、the contact pressure distribution between the disc and the pad, and is one of the main facto</p><p>　　The disc brake rotor consists of a hat section, neck section, air vent, and outboard and inboard plates.

35、Frictional heat, which occurs because of contact between the inboard and outboard plates and the brake pad, is assumed to be the main heat source of the rotor. Thermal processes such as heat conduction, convection, and r

36、adiation generate temperature gradients on the rotor and cause thermal deformation. In addition, the inboard and outboard thicknesses govern not only the local heat concentrat</p><p>　　The thermal deformatio

37、n of the rotor due to frictional heating produces a non-uniform pressure distribution between the disc and pad. The contact pressure between the rotor and pad highly affects the TEI and the mechanical instability. The fr

38、ictional heat source is a function of the normal force, friction coefficient, and relative velocity. This eccentric pressure distribution between the disc and pad arises because of the coning angle, run-out, DTV, and pre

39、ssurization type of caliper and can le</p><p>　　The coning angle has no fixed value because the temperature distribution of the rotor varies during driving. Generally, experiment and FEA through regulated br

40、aking condition are performed to achieve coning angles, thermal stress, and thermal capacity [25,28,29]. However, in this study, a uniform temperature distribution of 100 °C is assumed in the thermal FEA for finding

41、 the relative coning angle according to the rotor thicknesses. Through the simulation results, thermal behaviours were evaluat</p><p>　　The coning angles in accordance with the thicknesses of the brake disc

42、were calculated by a thermal structural FEA. Table 1 shows the simulation results for the coning angle and deflection of the inboard plate at 100 °C. The relative ratio of coning angle is the ratio between the conin

43、g angle of the rotor specimen and the base rotor. The results show that the coning angle has a relatively low absolute value. However, the relative coning angle difference is more important than the absolute coning</p

44、><p>　　A uniform pressure distribution between the rotor and lining is one of the most important factors in the optimal design. A uniform pressure distribution implies larger contact area, broader contact heat

45、 generation, and stiffer lining, which can result in hot spots and more noise in the brake system. A uniform pressure distribution can also cause brake NVH problems. However, to obtain highly efficient braking force unde

46、r stability, a uniform pressure distribution is more stable than a relatively</p><p>　　Thermomechanical coupling or thermal judder processes result in hot spots on the urface of a brake disc and unstable int

47、eraction between frictional heating,thermoelastic istortion , and elastic contact. It is well known, first, that the driver feels brake udder as vibrations in the steering wheel, brake pedal, and the floor (i