【正文】 ll look at some of the mon types of front and back suspensions typically used on mainstream cars. Front Suspension Dependent SystemsDependent front suspensions have a rigid front axle that connects the front wheels. Basically, this looks like a solid bar under the front of the car, kept in place by leaf springs and shock absorbers. Common on trucks, dependent front suspensions haven39。s best to look inside a shock absorber to see its structure and function. A shock absorber is basically an oil pump placed between the frame of the car and the wheels. The upper mount of the shock connects to the frame (., the sprung weight), while the lower mount connects to the axle, near the wheel (., the unsprung weight). In a twintube design, one of the most mon types of shock absorbers, the upper mount is connected to a piston rod, which in turn is connected to a piston, which in turn sits in a tube filled with hydraulic fluid. The inner tube is known as the pressure tube, and the outer tube is known as the reserve tube. The reserve tube stores excess hydraulic fluid. When the car wheel encounters a bump in the road and causes the spring to coil and uncoil, the energy of the spring is transferred to the shock absorber through the upper mount, down through the piston rod and into the piston. Orifices perforate the piston and allow fluid to leak through as the piston moves up and down in the pressure tube. Because the orifices are relatively tiny, only a small amount of fluid, under great pressure, passes through. This slows down the piston, which in turn slows down the spring. Shock absorbers work in two cycles the pression cycle and the extension cycle. The pression cycle occurs as the piston moves downward, pressing the hydraulic fluid in the chamber below the piston. The extension cycle occurs as the piston moves toward the top of the pressure tube, pressing the fluid in the chamber above the piston. A typical car or light truck will have more resistance during its extension cycle than its pression cycle. With that in mind, the pression cycle controls the motion of the vehicle39。s body, use the pressive qualities of air to absorb wheel vibrations. The concept is actually more than a century old and could be found on horsedrawn buggies. Air springs from this era were made from airfilled, leather diaphragms, much like a bellows。s engine and body, which are in turn supported by the suspension The suspension system setup that supports weight, absorbs and dampens shock and helps maintain tire contact The steering system mechanism that enables the driver to guide and direct the vehicle The tires and wheels ponents that make vehicle motion possible by way of grip and/or friction with the road So the suspension is just one of the major systems in any vehicle.SpringsToday39。s suspension, with its various ponents, provides all of the solutions described. Let39。s grip on the road.CorneringThe ability of a vehicle to travel a curved pathMinimize body roll, which occurs as centrifugal force pushes outward on a car39。s ability to absorb or isolate road shock from the passenger partmentAllow the vehicle body to ride undisturbed while traveling over rough roads.Absorb energy from road bumps and dissipate it without causing undue oscillation in the vehicle.Road HoldingThe degree to which a car maintains contact with the road surface in various types of directional changes and in a straight line (Example: The weight of a car will shift from the rear tires to the front tires during braking. Because the nose of the car dips toward the road, this type of motion is known as dive. The opposite effect squat occurs during acceleration, which shifts the weight of the car from the front tires to the back.)Keep the tires in contact with the ground, because it is the friction between the tires and the road that affects a vehicle39。s ability to smooth out a bumpy road Handling a car39。s laws of motion, all forces have both magnitude and direction. A bump in the road causes the wheel to move up and down perpendicular to the road surface. The magnitude, of course, depends on whether the wheel is striking a giant bump or a tiny speck. Either way, the car wheel experiences a vertical acceleration as it passes over an imperfection. Without an intervening structure, all of wheel39。t be necessary. But roads are far from flat. Even freshly paved highways have subtle imperfections that can interact with the wheels of a car. It39。ll explore how car suspensions work, how they39。t control the car. That39。還要感謝我的同學們,他們熱心的幫助,使我感到了來自兄弟姐妹的情誼；最后還要感謝相關資料的編著者和給予我們支持的社會各界人士, 感謝您們?yōu)槲覀兲?供一個良好的環(huán)境,使本次設計圓滿完成。參考文獻[1] [M].北京：清華大學出版社，2001[2] [M].北京：機械工業(yè)出版社，2004[3] [M].北京：人民交通出版社，2004[4] [M].北京：機械工業(yè)出版社，2004[5] [M]．北京：人民交通出版社，1995[6] 王 宣 譯. 懸架元件與底盤力學[M].北京：人民交通出版社，2004[7] [M].北京：機械工業(yè)出版社，2000[8] 魏彥召,周鋒,曾昀[J].；2005(6)[9] [M].浙江: 機械工業(yè)出版社，2007[10] 高衛(wèi)民,[J].同濟大學學報1997(5)［11］約森. 賴姆佩爾[德]著. 懸架元件及底盤力學[M]. 王玄譯. 長春：吉林科學技術出版社，1992[12] [M].北京 ：機械工業(yè)出版社，1996[13] [M].長春：吉林科學技術出版社，1998[14] . putational Methods in Multibody Dynamics[M].prentice [15],machinesandmeshanisms[M].pennsylvania,1998[16] 林逸，[M]. 人民交通出版社,1991致 謝畢業(yè)設計是對我們知識運用能力的一次全面的考核, 也是對我們進行科學研究基本功的訓練, 培養(yǎng)我們綜合運用所學知識獨立地分析問題和解決問題的能力, 為以后撰寫專業(yè)學術論文和工作打下良好的基礎。在完成畢業(yè)設計的時候， 我盡量的把畢業(yè)設計和實際工作有機的結合起來，實踐與理論相結合，這樣更有 利于自己能力的提高。這些工作使數(shù)據(jù)的選取更加適當，使所設計的汽車懸架系統(tǒng)的性能得到改善。在平順性分析中，建立兩自由度的平順性分析模型，取值繪制影響平順性的特性曲線。后懸架為半拖曳式懸架。設計的基本步驟為根據(jù)給定車型的各項基本參數(shù)計算出懸架的剛度，靜撓度，動撓度，以及減振器的阻尼系數(shù)，最大卸荷力，再經(jīng)過校核應力及平順性分析，選取適當尺寸進行裝配圖和零件圖的繪制。主要因素是路面的不平(它是振動的起源)還有例如懸架系統(tǒng)的鋼板彈簧片間的潤滑不良,等于增加了懸架剛度；減振器漏油等于減小了懸架系統(tǒng)的阻尼等。(4)非簧載質量在整車質量一定時，減小非簧載質量可改善平順性。研究表明，懸架阻尼的大小還對操縱穩(wěn)定性和制動方向穩(wěn)定性產(chǎn)生影響。（2）懸架阻尼汽車懸架系統(tǒng)中裝有減振器。汽車在實際使用中，簧載質量隨汽車的裝載情況而變，當值一定時，將隨減小而增大。（1）懸架剛度彈性元件是汽車懸架的主要組成部分，彈性元件的剛度或懸架等效剛度及其特性是影響平順性的主要因素。且阻尼比與幅頻值成反比，如圖85所示。頻率響應函數(shù)為 將 與 代入上式，得： 懸架系統(tǒng)對于車身位移來說，是將高頻輸入衰減的低通濾波器；對于動撓度來說，是將低頻輸入衰減的高通濾波器。