【正文】 lation，torque bar spring’s design，are presented and movement ofdouble—links indpendent suspension is analysed．So a soRware which isused to design optimal and analyse independent suspension is programmed．Meanwhile，me experiment to Verifythe result is made with the equipment ofthe front wheel alignment．Then an optimal design t0 mjnimize tyre、vear is perfonlled，whichbrings forward me way to reduce tyre wear throu optimal choosing andmodulating origina ldenpention cture of double1ink independent suspension andoptimizjng the cut point of track rodill．Futuremore，the memod oformogonal experiment is used to analyse t11e effect that tllestn cture a11d fixparameters of double1ink indendent suspension have on me suspension performance and tyre the most impotent factor and the second important factor are confiemed.KEY WoRDS: automobile，independent suspension，tyre wear， alignment paraeterSuspension Basics The suspension system, while not absolutely essential to the operation of a motor vehicle, makes a big difference in the amount of pleasure experienced while driving. Essentially, it acts as a bridge between the occupants of the vehicle and the road they ride on. The term suspension refers to the ability of this bridge to suspend a vehicle39。s almost a visceral experience. As the wheels growl across the pavement, picking up a bump here, a crack there, the vibration travels up your legs and settles in your gut. You could almost admit you were having fun, if you didn39。s ride support, let39。s undercarriage. Pivots located between the axle and the wheel spindles allow the wheels to swivel on each end. In solid axle suspension, because both wheels share the same axle, the up or down movement of one wheel causes a like movement in the other wheel. They respond as one unit. As you can imagine, this doesn39。ll find them in trucks and offroad vehicles[1]. A modified form of the solid axle design is called TwinIbeam suspension, or semirigid axle. In this setup, two rigid axles one for each wheel take the place of a single axle. This design offers many of the strengths of the solid axle design, with a slightly softer ride. You39。s ride, we can almost guarantee it has independent suspension. In addition to axles, wheels and tires, today39。s springs are the central part of the suspension. There are different designs of springs, such as torsion bars and leaf springs, but nearly all of today39。s rear suspension system. Springs absorb and store road shock caused by bumps, dips, cracks, and so forth (remember the skateboard analogy). They absorb this shock by either pressing or extending. When a car39。 for example, 100 pounds per inch. So, say a load of 200 pounds is applied, the spring will deflect 2 inches. Spring rate es from various factors. For a coil spring, this includes the number of active coils, the diameter of the coils, and the diameter of the spring wire. The fewer coils a spring has, the higher the spring rate it will have. The design of a spring affects how well the vehicle will ride and handle. A spring that absorbs lots of energy will generally offer a fortable ride. After all, it can absorb most of the road shock (energy) that is being generated by the road surface. But there are always engineering tradeoffs. This kind of spring generally requires a higher vehicle ride height, which will cause the vehicle to feel unstable during cornering. This instability is because the more distance a spring presses or extends, the more the vehicle rolls around on its suspension. This rolling is called weight transfer, and it is caused by centrifugal force acting on the weight of the vehicle as it goes around a corner. Weight transfer can overload a tire39。s suspension is the shock absorber. Contrary to its name, a shock absorber plays a minimal role in absorbing impacts taken by the suspension. That39。s job. A shock absorber dampens road impacts by converting the up and down oscillations of the spring into thermal energy. 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。t like the term shock absorbers。s you and me just call them shock absorbers. Without a shock absorber, a spring that has absorbed energy will release it by oscillating at an uncontrolled rate. The spring39。s an analogy. If you have a Slinky lying around and who doesn39。s spring absorbs road shock) and then bounce up and down, up and down (aka: oscillate), for a long time. This what an automotive spring does if it doesn39。ve heard the word strut, or, more formally, MacPherson strut. Struts are simply shock absorbers used as major structural members. For struts, the shock absorber is placed inside the coil spring. In addition to saving space, it often costs less. Many cars use a strut and struts help control how fast the suspension is allowed to move, which is important for keeping the tires in contact with the road. Most shock absorber designs have more resistance during the extension (rebound) cycle than the pression cycle[6]. This is because the extension cycle controls the motion of the vehicle39。re not, kits make it easy to install the bars at any time. So there you have it the basics of automotive suspension. We realize this is a simplistic view of a plex system. The Future of Car Suspensions While there have been enhancements and improvements to both springs and shock absorbers, the basic design of car suspensions has not undergone a significant evolution over the years. But all of that39