毕业外文翻译.docx

毕业外文翻译英文资料Suspension Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose contributing to the cars roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations,etc. These goals are generally at odds, so the tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the forces acting on the vehicle do so through the contact patches of the tires. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.Leaf springs have been around since the early Egyptians.Ancient military engineers used leaf springs in the form of bows to power their siege engines, with little success at first. The use of leaf springs in catapults was later refined and made to work years later. Springs were not only made of metal, a sturdy tree branch could be used as a spring, such as with a bow.Horse drawn vehiclesBy the early 19th century most British horse carriages were equipped with springs; wooden springs in the case of light one-horse vehicles to avoid taxation, and steel springs in larger vehicles. These were made of low-carbon steel and usually took the form of multiple layer leaf springs.1The British steel springs were not well suited for use on Americas rough roads of the time, and could even cause coaches to collapse if cornered too fast. In the 1820s, the Abbot Downing Company of Concord, New Hampshire developed a system whereby the bodies of stagecoaches were supported on leather straps called thoroughbraces, which gave a swinging motion instead of the jolting up and down of a spring suspension (the stagecoach itself was sometimes called a thoroughbrace)AutomobilesAutomobiles were initially developed as self-propelled versions of horse drawn vehicles. However, horse drawn vehicles had been designed for relatively slow speeds and their suspension was not well suited to the higher speeds permitted by the internal combustion engine.In 1903 Mors of Germany first fitted an automobile with shock absorbers. In 1920 Leyland used torsion bars in a suspension system. In 1922 independent front suspension was pioneered on the Lancia Lambda and became more common in mass market cars from 1932.2Important propertiesSpring rateThe spring rate (or suspension rate) is a component in setting the vehicles ride height or its location in the suspension stroke. Vehicles which carry heavy loads will often have heavier springs to compensate for the additional weight that would otherwise collapse a vehicle to the bottom of its travel (stroke). Heavier springs are also used in performance applications where the loading conditions experienced are more extreme.Springs that are too hard or too soft cause the suspension to become ineffective because they fail to properly isolate the vehicle from the road. Vehicles that commonly experience suspension loads heavier than normal have heavy or hard springs with a spring rate close to the upper limit for that vehicles weight. This allows the vehicle to perform properly under a heavy load when control is limited by the inertia of the load. Riding in an empty truck used for carrying loads can be uncomfortable for passengers because of its high spring rate relative to the weight of the vehicle. A race car would also be described as having heavy springs and would also be uncomfortably bumpy. However, even though we say they both have heavy springs, the actual spring rates for a 2000lb race car and a 10,000lb truck are very different. A luxury car, taxi, or passenger bus would be described as having soft springs. Vehicles with worn out or damaged springs ride lower to the ground which reduces the overall amount of compression available to the suspension and increases the amount of body lean. Performance vehicles can sometimes have spring rate requirements other than vehicle weight and load.Mathematics of the spring rateSpring rate is a ratio used to measure how resistant a spring is to being compressed or expanded during the springs deflection. The magnitude of the spring force increases as deflection increases according to Hookes Law. Briefly, this can be stated aswhereF is the force the spring exerts k is the spring rate of the spring. x is the displacement from equilibrium length i.e. the length at which the spring is neither compressed or stretched. Spring rate is confined to a narrow interval by the weight of the vehicle,load the vehicle will carry, and to a lesser extent by suspension geometry and performance desires.Spring rates typically have units of N/mm (or lbf/in). An example of a linear spring rate is 500lbf/in. For every inch the spring is compressed, it exerts 500lbf. A non-linear spring rate is one for which the relation between the springs compression and the force exerted cannot be fitted adequately to a linear model. For example, the first inch exerts 500lbf force, the second inch exerts an additional 550lbf (for a total of 1050lbf), the third inch exerts another 600lbf (for a total of 1650lbf). In contrast a 500lbf/in linear spring compressed to 3inches will only exert 1500lbf.The spring rate of a coil spring may be calculated by a simple algebraic equation or it may be measured in a spring testing machine. The spring constant k can be calculated as follows:where d is the wire diameter, G is the springs shear modulus (e.g., about 12,000,000 lbf/in or 80 GPa for steel), and N is the number of wraps and D is the diameter of the coil.Wheel rateWheel rate is the effective spring rate when measured at the wheel. This is as opposed to simply measuring the spring rate alone.Wheel rate is usually equal to or considerably less than the spring rate. Commonly, springs are mounted on control arms, swing arms or some other pivoting suspension member. Consider the example above where the spring rate was calculated to be 500lbs/inch, if you were to move the wheel 1inch (without moving the car), the spring more than likely compresses a smaller amount. Lets assume the spring moved 0.75inches, the lever arm ratio would be 0.75 to 1. The wheel rate is calculated by taking the square of the ratio (0.5625) times the spring rate. Squaring the ratio is because the ratio has two effects on the wheel rate. The ratio applies to both the force and distance traveled.Wheel rate on independent suspension is fairly straight-forward. However, special consideration must be taken with some non-independent suspension designs. Take the case of the straight axle. When viewed from the front or rear, the wheel rate can be measured by the means above. Yet because the wheels are not independent, when viewed from the side under acceleration or braking the pivot point is at infinity (because both wheels have moved) and the spring is directly inline with the wheel contact patch. The result is often that the effective wheel rate under cornering is different from what it is under acceleration and braking. This variation in wheel rate may be minimized by locating the spring as close to the wheel as possible.Roll couple percentageRoll couple percentage is the effective wheel rates, in roll, of each axle of the vehicle just as a ratio of the vehicles total roll rate. Roll Couple Percentage is critical in accurately balancing the handling of a vehicle. It is commonly adjusted through the use of anti-roll bars, but can also be changed through the use of different springs.A vehicle with a roll couple percentage of 70% will transfer 70% of its sprung weight transfer at the front of the vehicle during cornering. This is also commonly known as Total Lateral Load Transfer Distribution or TLLTD.Weight transferWeight transfer during cornering, acceleration or braking is usually calculated per individual wheel and compared with the static weights for the same wheels.The total amount of weight transfer is only affected by 4 factors: the distance between wheel centers (wheelbase in the case of braking, or track width in the case of cornering) the height of the center of gravity, the mass of the vehicle, and the amount of acceleration experienced.The speed at which weight transfer occurs as well as through which components it transfers is complex and is determined by many factors including but not limited to roll center height, spring and damper rates, anti-roll bar stiffness and the kinematic design of the suspension links.Unsprung weight transferUnsprung weight transfer is calculated based on the weight of the vehicles components that are not supported by the springs. This includes tires, wheels, brakes, spindles, half the control arms weight and other components. These components are then (for calculation purposes) assumed to be connected to a vehicle with zero sprung weight. They are then put through the same dynamic loads. The weight transfer for cornering in the front would be equal to the total unsprung front weight times the G-Force times the front unsprung center of gravity height divided by the front track width. The same is true for the rear.Suspension typeDependent suspensions include: Satchell link Panhard rod Watts linkage WOBLink Mumford linkage Live axle Twist beam Beam axle leaf springs used for location (transverse or longitudinal) The variety of independent systems is greater and includes: Swing axle Sliding pillar MacPherson strut/Chapman strut Upper and lower A-arm (double wishbone) multi-link suspension semi-trailing arm suspension swinging arm leaf springs Armoured fighting vehicle suspensionMilitary AFVs, including tanks, have specialized suspension requirements. They can weigh more than seventy tons and are required to move at high speed over very rough ground. Their suspension components must be protected from land mines and antitank weapons. Tracked AFVs can have as many as nine road wheels on each side. Many wheeled AFVs have six or eight wheels, to help them ride over rough and soft ground.The earliest tanks of the Great War had fixed suspensionswith no movement whatsoever. This unsatisfactory situation was improved with leaf spring suspensions adopted from agricultural machinery, but even these had very limited travel.Speeds increased due to more powerful engines, and the quality of ride had to be improved. In the 1930s, the Christie suspension was developed, which allowed the use of coil springs inside a vehicles armoured hull, by redirecting the direction of travel using a bell crank. Horstmann suspension was a variation which used a combination of bell crank and exterior coil springs, in use from the 1930s to the 1990s.By the Second World War the other common type was torsion-bar suspension, getting spring force from twisting bars inside the hullthis had less travel than the Christie type, but was significantly more compact, allowing the installation of larger turret rings and heavier main armament. The torsion-bar suspension, sometimes including shock absorbers, has been the dominant heavy armored vehicle suspension since the Second World War.中文翻译悬吊系统(亦称悬挂系统或悬载系统)是描述一种由弹簧、减震筒和连杆所构成的车用系统，用于连接车辆与其车轮。悬吊系统扮演双重的角色让车辆的操控和煞车合乎良好的动态安全与操驾乐趣，并保持车主的舒适性及隔绝适当的路面噪音、弹跳与震动。这些特性通常都是互相牵制的，因此悬吊的调整就必须找到两者兼顾的位置。悬吊系统同时也保护车辆本身、或车上的货物行李等，避免这些东西损坏或磨耗。一台车辆的前轮与后轮悬吊设计有可能会大不相同。在古早的埃及，就已经出现过板式弹簧的踪迹。古代的兵工学家使用板式弹簧，以弯曲的方式来加强他们的攻城武器，起初的效果还不错。后来在投石器上所使用的板式弹簧更为精密，而且可以使用好几年。弹簧不一定由金属制造，也可使用坚硬的树枝当作弹簧，就像制弓一样。马车在19世纪早期，大部分的英国四轮马车都有配备弹簧；木制弹簧用于轻型单马车辆来避税，而较大的马车弹簧则采用铁制。这些铁制的弹簧由低碳钢制成而且通常迭成多层成为板式弹簧。1英国的铁制弹簧不适用于当时美国大陆上粗糙不平的路面，转弯过快甚至会导致马车解体。在 1820 年代，新罕布什尔州康科德市的Abbot Downing 公司开发出一种系统，藉此让驿马车的车体能够支撑在称作thoroughbraces的皮带上，这样车厢的动态可改善成摆荡的动作，而不是像弹簧悬吊那样剧烈的上下震动。（有时驿马车本身也被称作thoroughbrace。）汽车汽车在早期开发时，视为自身动力推进的马车。但是相对来讲，马车是设计用来低速行驶的，因此它们的悬吊并不适用于内燃机引擎所能产生的高速行驶。1903年，德国的Mors汽车公司首次将车辆安装了减震筒。1920年，Leyland汽车公司在悬吊系统中加入了扭杆装置。1922年，Lancia Lambda开创先例地使用独立前轮悬吊，在1932年以后的市售车辆上更为常见。2重要属性弹簧刚性弹簧刚性（或称悬吊刚性）是悬吊伸缩时，用来设定车高或其定位的要素之一。车辆载重大的通常会搭配更硬的悬吊来抵销额外的重量负载，否则可能在途中（或弹跳时）压毁了车辆。较硬的弹簧通常也用于性能用途，因为这时候悬吊在弹跳时是经常性下压的，这时会导致可用的弹跳伸缩量变少，造成破坏性的下压力。弹簧太硬或太软都会造成车辆失去悬吊性能。一般来说，比较经常性载重的车辆具备较重或较硬的弹簧，其弹簧刚性接近车重的上限值。这样让车辆可以在控制性受载重惯性的限制下，正常地载货并操驾行驶。驾驶一台空的载货用卡车可能会对乘客感到较不舒适，是因为与车重相关的高弹簧刚性。赛车可以说是具备较硬的弹簧，而且会呈现不舒适的颠簸。然而，虽然我们说它们两者均具备硬弹簧，但实际上一台2000磅的赛车与一台10000磅的卡车，其两者的弹簧刚性则是全然不同的。高级房车、的士或客运巴士通常可以说是具备较软的弹簧。车辆的弹簧若是老化或损坏，行驶时容易贴近地面，悬吊的总压缩量会降低，车体也容易侧倾。性能跑车的弹簧刚性有时不只是为了车重或载重的需求。弹簧刚性的数学应用弹簧刚性是一个比值，用来测量一个弹簧在偏斜时被压缩或伸展时的阻抗。按照虎克定律，弹力强度随着偏斜增加而增加。简单来讲，这个现象可以由下列公式所述：其中F 为弹簧的施力 k 为弹簧的刚性 x 为静力平衡时的位移量，其长度为弹簧压缩或延展时。 由于本身车重、车辆载重、悬吊系统的空间限制或性能需求等因素下，弹簧刚性会受限在一段狭小的分布区段。弹簧刚性的单位通常由N/mm表示（或lbf/in）。例如一个线性的弹簧刚性表示为 500 lbf/in，其代表弹簧每压缩一英吋，它可以施压 500 磅力。而一个具有非线性的弹簧刚性，代表它的压缩力与施力的关系无法适当地对应于一个线性模型。例如，第一英吋会施压 500 磅力，第二英吋会施压额外的 550 磅力（因此总共是 1050 磅力），第三英吋则会施压另外 600 磅力（总共达 1650 磅力）。相较之下，一个 500 lbf/in 的线性弹簧压缩了三英吋之后的施压力则只有 1500 磅力。线圈弹簧的弹簧刚性可由简单的代数方程来计算求得，或是由弹簧测试机来测量。弹簧常数k可由下列公式计算：其中d为线材直径，E为弹簧的弹性系数（例如钢铁的系数大约为 30,000,000 lbf/in 或是 207 GPa），N为线圈的缠绕次数，而D为线圈直径。悬架刚性悬架刚性为针对车辆轮架所测量出有效的弹簧刚性，但不只是单独对弹簧刚性做测量而已。悬架刚性通常等于或小于弹簧刚性。一般来说，弹簧会固定在控制臂、摇臂或某些其他种类的枢轴支承机构上。假设前述例子中的弹簧刚性计算出为每吋 500 磅力，如果你将车轮垂直移动一英吋（车辆是静止的），则弹簧可能仅压缩了一小部份的量。假设弹簧只移动了 0.75 英吋，杠杆臂比率可能为 0.75 到 1 ，则悬架刚性可由弹簧刚性比值的平方倍（0.5625）而求得。将比值做平方倍的目的在于它对于悬架刚性有两个作用存在，这个比值同时影响了施力大小与位移量。3独立悬吊系统下的悬架刚性就非常简单明了，但对于某些非独立悬吊系统的设计就必须考虑到一些特殊状况。以车轴的纵向角度来看，若由前方或后方来看，悬架刚性可以由前述的方式去测量得出。然而由于轮架并非独立的，在加速或减速时侧向来看，支点会位在无限远的位置（因为前后轮都移动了）。过弯与加减速时的有效悬架刚性也往往有不一样的结果，将弹簧的定位尽可能地靠近车轮可以将悬架刚性的差异降到最小。侧倾力耦百分比在车辆摇晃时，侧倾力耦百分比为车身各轴在线发生