Related Research Articles
Vehicle dynamics is the study of vehicle motion, e.g., how a vehicle's forward movement changes in response to driver inputs, propulsion system outputs, ambient conditions, air/surface/water conditions, etc. Vehicle dynamics is a part of engineering primarily based on classical mechanics. It may be applied for motorized vehicles, bicycles and motorcycles, aircraft, and watercraft.
The unsprung mass of a vehicle is the mass of the suspension, wheels or tracks, and other components directly connected to them. This contrasts with the sprung mass supported by the suspension, which includes the body and other components within or attached to it. Components of the unsprung mass include the wheel axles, wheel bearings, wheel hubs, tires, and a portion of the weight of driveshafts, springs, shock absorbers, and suspension links. Brakes that are mounted inboard are part of a vehicle's sprung mass.
Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/handling and ride quality, which are at odds with each other. 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 road or ground 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.
Automobile handling and vehicle handling are descriptions of the way a wheeled vehicle responds and reacts to the inputs of a driver, as well as how it moves along a track or road. It is commonly judged by how a vehicle performs particularly during cornering, acceleration, and braking as well as on the vehicle's directional stability when moving in steady state condition. Numerous factors affect handling
Car tuning is the modification of a car to optimise it for a different set of performance requirements from those it was originally designed to meet. Most commonly this is higher engine performance and dynamic handling characteristics but cars may also be altered to provide better fuel economy, or smoother response. The goal when tuning is the improvement of a vehicle's overall performance in response to the user's needs. Often, tuning is done at the expense of emissions performance, component reliability and occupant comfort.
An anti-roll bar is an automobile suspension part that helps reduce the body roll of a vehicle during fast cornering or over road irregularities. It links opposite front or rear wheels to a torsion spring using short lever arms for anchors. This increases the suspension's roll stiffness—its resistance to roll in turns.
A beam axle, rigid axle or solid axle is a dependent suspension design in which a set of wheels is connected laterally by a single beam or shaft. Beam axles were once commonly used at the rear wheels of a vehicle, but historically they have also been used as front axles in four-wheel-drive vehicles. In most automobiles, beam axles have been replaced with front (IFS) and rear independent suspensions (IRS).
Fishtailing is a vehicle handling problem which occurs when the rear wheels lose traction, resulting in oversteer. This can be caused by low-friction surfaces. Rear-drive vehicles with sufficient power can induce this loss of traction on any surface, which is called power-oversteer.
A tactile transducer or "bass shaker" is a device which is made on the principle that low bass frequencies can be felt as well as heard. They can be compared with a common loudspeaker, just that the diaphragm is missing. Instead, another object is used as a diaphragm. A shaker transmits low-frequency vibrations into various surfaces so that they can be felt by people. This is called tactile sound. Tactile transducers may augment or in some cases substitute for a subwoofer. One benefit of tactile transducers is they produce little or no noise, if properly installed, as compared with a subwoofer speaker enclosure.
Vibration isolation is the prevention of transmission of vibration from one component of a system to others parts of the same system, as in buildings or mechanical systems. Vibration is undesirable in many domains, primarily engineered systems and habitable spaces, and methods have been developed to prevent the transfer of vibration to such systems. Vibrations propagate via mechanical waves and certain mechanical linkages conduct vibrations more efficiently than others. Passive vibration isolation makes use of materials and mechanical linkages that absorb and damp these mechanical waves. Active vibration isolation involves sensors and actuators that produce disruptive interference that cancels-out incoming vibration.
Bicycle and motorcycle dynamics is the science of the motion of bicycles and motorcycles and their components, due to the forces acting on them. Dynamics falls under a branch of physics known as classical mechanics. Bike motions of interest include balancing, steering, braking, accelerating, suspension activation, and vibration. The study of these motions began in the late 19th century and continues today.
A motorcycle's suspension serves a dual purpose: contributing to the vehicle's handling and braking, and providing safety and comfort by keeping the vehicle's passengers comfortably isolated from road noise, bumps and vibrations.
Modal analysis is the study of the dynamic properties of systems in the frequency domain. It consists of mechanically exciting a studied component in such a way to target the modeshapes of the structure, and recording the vibration data with a network of sensors. Examples would include measuring the vibration of a car's body when it is attached to a shaker, or the noise pattern in a room when excited by a loudspeaker.
Noise, vibration, and harshness (NVH), also known as noise and vibration (N&V), is the study and modification of the noise and vibration characteristics of vehicles, particularly cars and trucks. While noise and vibration can be readily measured, harshness is a subjective quality, and is measured either via jury evaluations, or with analytical tools that can provide results reflecting human subjective impressions. The latter tools belong to the field psychoacoustics.
Automotive suspension design is an aspect of automotive engineering, concerned with designing the suspension for cars and trucks. Suspension design for other vehicles is similar, though the process may not be as well established.
Tire balance, also called tire unbalance or tire imbalance, describes the distribution of mass within an automobile tire or the entire wheel on which it is mounted.
A 4-poster or four poster is an automotive test system specifically designed for the testing of vehicles. These test systems consist of 4 hydraulic actuators on top of which the wheels of the vehicle are placed. Movements of the actuators simulate the road surface and forces exerted by the road on the wheels. The movements of the system are tightly controlled by a digital test controller. During the research phase of a vehicle, a 4-poster system is used to test newly designed suspension systems and their durability. In production, 4-poster systems are typically used to test every vehicle at the end of the production line on squeak and rattle, which is a check to make sure the vehicle doesn't have any loose parts. Multiple kinds of tests are possible: sine test, simple wave form on each actuator, open loop test. There is also a particular testing method called ICS control, which allows to reproduce on a car an actual service environment, starting from those data coming from the outdoor acquisition sessions.
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. Vibration may be deterministic if the oscillations can be characterised precisely, or random if the oscillations can only be analysed statistically.
Vibration calibrators , sometimes also called reference shakers, are electromechanical instruments which enable calibration of vibration sensors and measuring instruments to traceable standards. They produce sinusoidal mechanical vibration signals with known amplitudes and frequencies. The vibrating part of the instrument is usually a cylindrical steel stud with an internal thread for attachment of the test object. An electrodynamic or piezoelectric actuator system is used to produce the vibrations. With older instruments it was necessary to adjust the vibration amplitude according to the weight of the test object. However, modern instruments contain a built-in reference accelerometer and closed-loop control, with which the amplitude is kept constant up to a maximum specified weight of test object. Older models can be used to calibrate objects weighing up to a maximum of approximately 100 g, whereas the latest instruments can work stably with test objects weighing over 500 g.
Pull-rod suspension and push-rod suspension refer to a specialised type of automotive suspension system which is largely based on a double-wishbone system, incorporating elements of the commonly used MacPherson strut.
References
- ↑ Seven-Post Shaker Rig - Suspension Dynamics Machine - Circle Track
- ↑ "F1 - Grandprix.com > Features > Technical > Movers and shakers". Archived from the original on 2008-02-28. Retrieved 2008-02-26.
- ↑ ARC 7-Post