Car handling and vehicle handling are descriptions of how a wheeled vehicle responds and reacts to a driver's input, as well as how it travels along a track or road. This is generally assessed by how the performance of the vehicle especially when cornering, acceleration, and braking and on the directional stability of the vehicle when moving in steady conditions.
In the automotive industry, handling and braking are major components of the vehicle's "active" safety, as well as its ability to perform at Auto Racing. The maximum lateral acceleration is sometimes discussed separately as "braking". (This discussion is directed at road vehicles with at least three wheels, but some may apply to other ground vehicles). Cars are driven on public roads whose engineering requirements emphasize the handling of comfort and passenger space given the name of a sports car.
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Center of mass height
Center height of the masses, relative to the track, determines the load displacement (related, but not exactly heavy displacement) from side to side and causes the body lean. When a vehicle tire provides a centripetal force to pull it around the turn, the momentum of the vehicle moves the load transfer in the direction that moves from the current vehicle position to the point on the track that intersects the vehicle path. This load transfer comes naturally in the form of a slim body. In extreme circumstances, the vehicle can roll over.
The height of the center of the mass relative to the wheelbase determines the load transfer between front and rear. The momentum of the car acts at its center of mass to tilt the car forward or backward, each during braking and acceleration. Since only the downward force is changed and not the location of the center of mass, the effect on the over/under steer is opposite to the actual change in the center of mass. When the car brakes, the load down on the front tire rises and on the back decreases, with the corresponding change in their ability to take the load sideways.
The lower mass centers are the main performance advantages of sports cars, compared to sedans and (especially) SUVs. Some cars have body panels made of lightweight materials partly for this reason.
The sleek body can also be controlled by springs, anti-roll bars or the height of the roll center.
Mass center
In stable conditions around the corner, the front-weight car tends to shrink and the car weighs into the oversteer, all other things being equal. The mid-engine design seeks to reach the ideal mass center, although the front-engine design has the advantage of allowing a more practical engine-passenger-luggage layout. All other parameters are the same, in the hands of a neutrally-balanced, mid-engine car driver capable of angling more quickly, but a FR (front-engined, rear-wheel drive) FR layout car is easier to drive at its limit.
Rear-weight bias is favored by cars and race cars resulting from effects handling during the transition from straight forward to cornering. During entering the front tire angle, in addition to producing parts of the lateral force necessary to accelerate the center of the car's mob to the turn, it also produces torque about the vertical axis of the car that starts the car turning to the turn. However, the lateral force generated by the rear tire acts in the opposite torsional sense, trying to turn the car out of the turn. For this reason, cars with weight distribution "50/50" will shrink on initial angle entries. To avoid this problem, sports and racing cars often have more weight distribution to the back. In the case of pure race cars, this is usually between "40/60" and "35/65". It gives an edge on the front tires in overcoming moments of car inertia (jaw angular inertia), thus reducing the incoming-angle understeer.
Using wheels and tires of different sizes (proportional to the weight carried by each end) is a lever car that can be used to perfect the over/understeer characteristics generated.
Roll inertial angular
Ini meningkatkan yak diperlukan untuk menetap dan mengikuti kemudi. Itu tergantung falls on tinggi dan lebar (persegi dari), dan (untuk distribusi massa seragam) dapat kira-kira dihitung dengan persamaan:
With a larger width, then, even though it is against the height of the center of gravity, handling pain by increasing angular inertia. Some high-performance cars have lightweight materials on the fenders and the roof is partly for this reason
Yaw and pitch angle inertia (pole moments)
SuspensionCar suspensions have many variable characteristics, which are generally different in front and back and all affect handling. Some of them are: spring speed, damping, straight front camber angle, camber changes with wheel travel, mid-roll height and flexibility and vibration mode suspension element. Suspension also affects the weight of unsprung.
Many cars have a suspension that connects the wheels on both sides, either by swinging bars and/or by a solid axle. CitroÃÆ'¡n 2CV has an interaction between the front and rear suspension.
The flexing of the frame interacts with the suspension. (See below.)
Spring rates
The following types of springs are commonly used for car suspension, variable level spring and linear rate spring. When the load is applied to a linear level, the spring spring suppresses the amount proportional to the applied load. This type of spring is commonly used in street racing applications when the quality of the vehicle is not a concern. The linear spring will behave the same every time. It provides predictable handling characteristics during cornering, acceleration and high speed braking. The variable springs have low baseline springs. The spring rate gradually increases as it is compressed. Simply put, the spring becomes stiff because it is compressed. The edge of the spring is wrapped more tightly to produce a lower spring rate. When driving these pillows the imperfections of the small roads improve the quality of driving. However once the spring is compressed to a certain point, the spring will not wrap so tightly that it gives a higher spring rate (firmer). This prevents excessive suspension compression and prevents harmful body roll, which can cause a roll over. The variable level spring is used in cars designed for comfort as well as off road racing vehicles. In off road racing they allow the vehicle to absorb hard shocks from jumps effectively and absorb small bumps along the off road terrain effectively.
Suspension tour
The severe handling representatives of the TR3B and related automobiles are caused by endless travel suspensions. (See below.) Other vehicles will run out of suspension trips with some combination of bumps and bends, with similar catastrophic effects. Excessively modified cars may also face this problem.
Tires and wheels
In general, softer rubber, higher hysteresis rubber and rigid cable configurations improve road containment and improve handling. On most types of bad surfaces, large diameter wheels perform better than wider lower wheels. The remaining tread depth greatly affects aquaplaning (rises above the deep water without reaching the road surface). Increasing the tire pressure reduces the angle of their slip, but reduces the adverse contact area under ordinary surface conditions and should be used with caution.
The number of tires that fill the road is the similarity between the weight of the car and the type (and size) of the tire. A 1000kg car can hit 185/65/15 tires over 215/45/15 longitudinal tires so that it has better linear grip and better braking distance not to mention better aquaplaning performance, while wider tires have a cornering resistance which is better (dry).
The contemporary chemical makeup of the tires depends on the ambient temperature and the road. Ideally the tire should be soft enough to fit the road surface (so it has a good handle), but hard enough to last long enough (distance) to be economically viable. It's usually a good idea to have different sets of summer and winter tires for the climate to have this temperature.
Track and wheelbase
The axle track provides resistance to lateral load transfer and lean body. Wheelbase provides resistance to long load transfers and to throw angular inertia, and provides torque lever arm to rotate the car when turning. Wheelbase, however, is less important than angular inertia (polar moments) to the ability of the vehicle to turn quickly.
Wheelbase contributes to the vehicle's rotational radius, which is also a handling characteristic.
Weight unsprung
Ignoring the elasticity of other components, the car can be modeled as a popping weight, carried by a spring, carried by unsprung weight, carried by a tire, carried by the road. Unsprung weight is more appropriately considered a mass that has its own inertia that is separate from the rest of the vehicle. When the wheel is pushed upward by a bump in the road, the inertia of the wheel will cause it to be carried further upward above the height of the bulge. If the thrust is large enough, the inertia of the wheel will cause the tire to be completely lifted off the road surface resulting in traction and control loss. Similarly when crossing into a sudden depression of the soil, wheel inertia slows down the rate of decline. If the inertia of the wheel is large enough, the wheels may be temporarily separated from the road surface before descending back to the road surface.
This unsprung weight is carried away from uneven road surfaces only by tire compression resistance (and wire wheels when mounted), which helps the wheels stay in contact with the road surface when the inertial wheel prevents the adjacent ground surface. However, tire compression resistance produces rolling resistance requiring additional kinetic energy to overcome it, and rolling resistance is spent on the tires as heat due to the flexing of rubber and steel bands on the tire sidewall. To reduce rolling resistance to improve fuel economy and to avoid overheating and tire failure at high speeds, tires are designed to have limited internal damping.
Thus the "wheels bounce" due to the inertial wheel, or the resonance motion of the unsprung weight that moves up and down the tire's flexibility, is only less damped, especially by silencers or shock absorbers. For this reason, high unsprung weight reduces road control and increases unexpected changes in direction on rough surfaces (as well as reduces ride comfort and increases mechanical load).
This unsprung weight includes wheels and tires, usually brakes, plus a few percent of the suspension, depending on how many suspensions move with the body and how much with the wheels; for example a solid shaft suspension is completely unsprung. The main factors that increase unsprung weight are differential popping (as opposed to live axis) and brake in the vessel. (The De Dion tube suspension operates much like a live axle, but represents an improvement because the differential is attached to the body, thus reducing the weight of the unsprung.) Material and wheel size will also have an effect. Aluminum wheels are common because of their heavy characteristics that help reduce unsprung mass. Magnesium wheels are even lighter but easily rusty.
Since only the brakes on the drive wheel can easily fit in, CitroÃÆ'¡n 2CV has an inertial damper on its rear wheel hub to moisten the wheels only.
Aerodynamics
The aerodynamic style is generally proportional to the square of the air velocity, therefore the car's aerodynamics becomes faster rapidly as the speed increases. Such as darts, airplanes, etc., Cars can be stabilized by fins and other rear aerodynamic devices. However, in addition to this car also uses downforce or "negative elevator" to improve road holding. It stands out in many types of racing cars, but is also used on most passenger cars to some degree, if only to negate the tendency of the car to otherwise generate a positive lift.
In addition to providing increased adhesion, car aerodynamics are often designed to offset the inherent increase in the oversteer when cornering speeds increase. When the corners of the car, it must rotate on its vertical axis and translate its mass center in the arc. However, in the narrower angle (lower speed) angle the car's corner speed is high, while at a longer angle (higher speed) the angular velocity angle is much lower. Therefore, the front tires have a more difficult time to overcome the moment of car inertia when entering the bend at low speeds, and much less trouble when cornering speeds increase. So the natural tendency of every car is understeer when it enters to a low-speed corner and an oversteer when entering a high-speed corner. To compensate for this inevitable effect, car designers often deviate from handling cars to less understeer entry angles (such as by lowering the center of the front winding), and adding backward bias to aerodynamic downforce to offset corners at higher speeds. Backward aerodynamic bias can be achieved by airfoil or "spoiler" mounted near the rear of the car, but a useful effect can also be achieved by forming the body as a whole, especially the stern area.
In recent years, aerodynamics has become an area of ​​increased focus by racing teams as well as car manufacturers. Advanced tools such as wind tunnels and computational fluid dynamics (CFDs) have enabled engineers to optimize vehicle handling characteristics. Sophisticated wind tunnels such as Full Scale Wind Winds, Rolling Streets, Automotive Wind Tunnel recently built in Concord, North Carolina have simulated road conditions leading to the highest degree of accuracy and repeatability under highly controlled conditions. CFDs have also been used as a tool to simulate aerodynamic conditions but through the use of highly sophisticated computers and software to duplicate car design digitally and then "test" the design on a computer.
Shipping power to wheels and brakes
The rubber coefficient of friction on the road limits the amount of cross-sectional and longitudinal vector summation. So the wheels are driven or that supply the most braking tend to slip to the side. This phenomenon is often explained by using the circle of forces model.
One of the reasons that a sports car is usually a rear-wheel drive is a handy, excessive power move, for skilled drivers, for tight bends. Heavy transfer under acceleration has the opposite effect and may dominate, depending on the conditions. Pushing the oversteer by applying force in the front-wheel drive car is made possible through the proper use of "Braking the left foot." In any case, this is not an important security issue, since electricity is not normally used in emergency situations. Using a low gear down a steep hill can cause some oversteer.
The braking effect on handling is complicated by the load transfer, which is proportional to acceleration (negative) times the height ratio of the center of gravity to the wheelbase. The difficulty is that the acceleration at the adhesion limit depends on the road surface, so with the same ratio from front to back braking power, the car will understeer under braking on slippery and oversteer surfaces under hard braking on solid surface. Most modern cars fight this by varying the distribution of braking in several ways. This is important with the high center of gravity, but it is also done on low middle gravity cars, from which higher performance levels are expected.
Steering
Depending on the driver, steering force and power transmission the way back to the steering wheel and steering ratio of the steering wheel to the wheel rotation affect the control and awareness. Rotate - free rotation of the steering wheel before the wheel spins - is a common problem, especially in older models and worn cars. The other is friction. Rack and pinion steering are generally considered to be the best kind of mechanism for control effectiveness. This linkage also contributes to the game and friction. Casters - offset the steering axis of the contact patch - give some selfish tendencies.
The accuracy of the steering wheel is very important in ice or snow that is difficult to pack where the slip angle on adhesion limits is smaller than on the dry road.
The steering effort depends on the downward force on the steering wheel and on the contact patch radius. So for constant tire pressure, it's like a power of 1.5 from the weight of the vehicle. The ability of the driver to exert torque on the wheel scales is the same as his body size. The wheels must be rotated further on the longer car to be played with a certain radius. Power steering reduces the force required at the expense of nuance. This is useful, especially in the parking lot, when the weight of the front weight vehicle exceeds about ten or fifteen times the driver's weight, for the physically handicapped driver and when there is much friction in the steering mechanism.
Four wheel wheels have started to be used on road cars (Some WW II surveillance vehicles have them). This reduces the effect of inertial angle by starting the entire car in motion before rotating in the desired direction. It can also be used, in the other direction, to reduce the turn radius. Some cars will do one or the other, depending on speed.
Steam geometry changes due to the bulge in the road can cause the front wheels to aim in different directions simultaneously or independently of each other. Steering relationships should be designed to minimize this effect.
Electronic stability control
Electronic stability control (ESC) is a computerized technology that improves vehicle stability by trying to detect and prevent deterioration. When the ESC detects a loss of steering control, the system will apply individual brakes to help "drive" the vehicle where the driver wants to go. Braking is automatically applied to individual wheels, such as an outer front wheel to counter an oversteer, or an inner rear wheel to counter the understeer.
The stability control of some cars may not be compatible with some driving techniques, such as power induced over-steer. Therefore, at least from a sports point of view, it is preferable that it be disabled.
Static wheel alignment
Of course everything must be the same, left and right, for the road car. The camber affects the wheel because the tire produces a force toward the side whose top is leaning toward it. This is called camber's impulse. An additional negative front camber is used to improve the cornering ability of the car with insufficient camber gain.
Stiffness frame
Frames may bend with weights, especially turning on bumps. Stiffness is considered helpful handling. At least it simplifies the work of suspension engineers. Some cars, such as the Mercedes-Benz 300SL have high doors to allow a more rigid frame.
Maps Automobile handling
Car-handling driver
Handling is the property of the car, but different characteristics will work well with different drivers.
Familiarity
The more experience a person has with a car or type of car, the more likely they will take full advantage of the characteristics of handling it in adverse conditions.
Position and support for drivers
Must hold "g forces" on his arm interfere with the right driver's wheel. In the same way, lack of support for the driver's seat position can cause them to move when the car accelerates quickly (through cornering, takeoff or braking). This interferes with precise control inputs, making the car more difficult to control.
Being able to control easily is also an important consideration, especially if the car is being pushed hard.
Under certain circumstances, good support may allow the driver to maintain control, even after a minor accident or after the first stage of an accident.
External conditions affecting handling
Weather
Weather affects the handling by changing the amount of traction available on the surface. Different tires are best in different weather. Deep water is the exception to the rule that wider tires increase the mastery of the road. (See aquaplaning under the tire, below.)
Road conditions
Cars with relatively soft suspension and with low unsprung weight are at least influenced by uneven surfaces, whereas on smooth surfaces the harder is better. Water, ice, oil, etc. What is not expected is danger.
Common handling issues
When each wheel leaves contact with the road there is a change in handling, so the suspension should keep the fourth (or three) wheels on the road despite hard cornering, turning and bumps on the road. This is very important for handling, as well as other reasons, for not running out of suspension and "down" or "top" travel.
It is usually most desirable to have a car adjusted for a small amount of understeer, so the response can be predicted against the steering wheel and the rear wheels have smaller slip angles than the front wheels. However this may not be achievable for all loading, road and weather conditions, speed range, or when spinning under acceleration or braking. Ideally, the car should carry passengers and luggage near its center of gravity and have the same tire loading, camber angle and rear stiffness in front and rear to minimize variations in handling characteristics. A driver can learn to handle oversteer or understeer overload, but not if it varies greatly in a short period of time.
The most important handling failures are; Understand - the front wheel tends to crawl a little or even slip and drift toward the outside of the turn. The driver can compensate by turning a bit more tightly, but the road-holding is reduced, the car's behavior is less predictable and the tires can be charged faster.
Compromise
Quality and driving handling has always been a compromise - technology has allowed car manufacturers to combine more than both features in the same vehicle. High comfort levels are difficult to reconcile with low center of gravity, body roll resistance, low angle inertia, support for drivers, shades of steering, and other characteristics that make the car work properly.
For regular production cars, it produces err against understeer deliberate because it is safer for inexperienced or inattentive drivers than oversteer. Other compromises involve convenience and usability, such as preferences for smoother driving or more seating capacity.
The in-flight brake improves both handling and comfort but takes up space and is harder to cool down. Large engines tend to make the front or rear car weight. Fuel economy, staying cool at high speeds, driving comfort and long wear all tend to run counter to street control, while wet, dry, deep water and snow roads are not fully compatible. A-arm or wishbone front suspension tends to provide better handling, as it gives engineers more freedom to choose geometry, and more road holds, because camber is more suitable for radial tires, than MacPherson strut, but requires more space.
The older rear axle rear suspension technology, known from the Ford Model T, is still widely used in most SUVs and trucks, often for durability (and cost). The active axle suspension is still used in some sports cars, such as the Ford Mustang (model year before 2015), and is better for drag racing, but generally has problems with grip on wavy corners, fast angles and stability at high speeds on corrugated straight.
Aftermarket modifications and adjustments
Lowering the center of gravity will always help the handling (as well as reduce the possibility of roll-over). This can be done to some extent by using plastic (or non-existent) windows and lightweight roofing, bonnet and boot lid, by reducing ground clearance, etc. Increasing the trajectory with an "upside down" wheel will have a similar effect, but the wider the car, the fewer empty spaces on the road and the further it has to turn to miss the obstacles. Rigid springs and/or shocks, both front and rear, will generally improve handling on near-perfect surfaces, while poorer handling of less than perfect road conditions by "skipping" the car (and destroying the grip), thus making handling difficult vehicles. The after sales performance suspension kit is usually available.
Lighter wheels (mostly aluminum or magnesium alloys) improve handling and ride comfort, by reducing unsprung weight.
Moments of inertia can be reduced by using bumpers and lighter wings (fenders), or none at all.
Fixed understeer or oversteer conditions achieved by increasing or decreasing the grip on the front or rear axle. If the front axle has more grip than a vehicle similar to the neutral steering characteristics, the vehicle will be oversteer. The oversteering vehicle may be "tuned" by hopefully increasing the rear axle grip, or alternatively by reducing the front axle axle. The reverse is true for the understeering vehicle (the rear axle has an excessive grip, improved by increasing the front grip or reducing the rear grip). The following actions will have a tendency to "increase the grip" of the axle. Increase arm spacing when to cg, reduce lateral load transfer (soften shock, soften rocking bars, increase track width), increase tire contact patch size, increase longitudinal load transfer to the shaft, and reduce tire pressure.
Cars with unusual handling problems
Source of the article : Wikipedia
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