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# Vehicle dynamics

For vehicles such as cars, vehicle dynamics is the study of how the vehicle will react to driver inputs on a given road. [1]

84 relations: Ackermann steering geometry, Aerodynamics, Analytical dynamics, Automobile drag coefficient, Automobile layout, Automotive aerodynamics, Automotive suspension design, Axle track, Body flex, Body roll, Brake, Bump steer, Bundorf analysis, Camber angle, Camber thrust, CarSim, Caster angle, Center of mass, Center of pressure (fluid mechanics), Circle of forces, Classical mechanics, Contact patch, Cornering force, Degrees of freedom (mechanics), Directional stability, Downforce, Driving simulator, Electronic stability control, Engineering, Fishtailing, Flight dynamics (fixed-wing aircraft), Frequency response, Geometry, Ground effect (cars), Ground pressure, Hans B. Pacejka, Hunting oscillation, Lane, Lift-off oversteer, Mass, Modelica, Moment of inertia, Moose test, MSC Software, Multibody system, Noise, vibration, and harshness, Pneumatic trail, Powertrain, Radial force variation, Relaxation length, ... Expand index (34 more) »

## Ackermann steering geometry

Ackermann steering geometry is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radii.

## Aerodynamics

Aerodynamics, from Greek ἀήρ aer (air) + δυναμική (dynamics), is the study of the motion of air, particularly its interaction with a solid object, such as an airplane wing.

## Analytical dynamics

In classical mechanics, analytical dynamics, or more briefly dynamics, is concerned with the relationship between motion of bodies and its causes, namely the forces acting on the bodies and the properties of the bodies, particularly mass and moment of inertia.

## Automobile drag coefficient

The drag coefficient is a common measure in automotive design as it pertains to aerodynamics.

## Automobile layout

In automotive design, the automobile layout describes where on the vehicle the engine and drive wheels are found.

## Automotive aerodynamics

Automotive aerodynamics is the study of the aerodynamics of road vehicles.

## Automotive suspension design

Automotive suspension design is an aspect of automotive engineering, concerned with designing the suspension for cars and trucks.

## Axle track

The axle track in automobiles and other wheeled vehicles which have two or more wheels on an axle, is the distance between the centerline of two roadwheels on the same axle.

## Body flex

Body flex is a lack of rigidity in a motor vehicle's chassis.

## Body roll

On wheeled or tracked vehicles, body roll is a reference to the load transfer of a vehicle towards the outside of a turn.

## Brake

A brake is a mechanical device that inhibits motion by absorbing energy from a moving system.

## Bump steer

Bump steer or roll steer is the term for the tendency of the wheel of a car to steer itself as it moves through the suspension stroke.

## Bundorf analysis

A Bundorf analysis is a measure of the characteristics of a vehicle that govern its understeer balance.

## Camber angle

From the front of the car, a right wheel with a negative camber angle Camber angle is the angle made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of the wheels used for steering and the vertical axis of the vehicle when viewed from the front or rear.

## Camber thrust

Camber thrust and camber force are terms used to describe the force generated perpendicular to the direction of travel of a rolling tire due to its camber angle and finite contact patch.

## CarSim

CarSim is a commercial software package that predicts the performance of vehicles in response to driver controls (steering, throttle, brakes, clutch, and shifting) in a given environment (road geometry, coefficients of friction, wind).

## Caster angle

θ is the caster angle, the red line is the pivot line, and the grey area is the tire. The caster angle or castor angle is the angular displacement of the steering axis from the vertical axis of a steered wheel in a car, motorcycle, bicycle or other vehicle, measured in the longitudinal direction.

## Center of mass

In physics, the center of mass of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero, or the point where if a force is applied it moves in the direction of the force without rotating.

## Center of pressure (fluid mechanics)

The center of pressure is the point where the total sum of a pressure field acts on a body, causing a force to act through that point.

## Circle of forces

The circle of forces, traction circle, friction circle, or friction ellipse is a useful way to think about the dynamic interaction between a vehicle's tire and the road surface.

## Classical mechanics

Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, and astronomical objects, such as spacecraft, planets, stars and galaxies.

## Contact patch

Contact patch is the portion of a vehicle's tire that is in actual contact with the road surface.

## Cornering force

Cornering force or side force is the lateral (i.e., parallel to the road surface) force produced by a vehicle tire during cornering.

## Degrees of freedom (mechanics)

In physics, the degree of freedom (DOF) of a mechanical system is the number of independent parameters that define its configuration.

## Directional stability

Directional stability is stability of a moving body or vehicle about an axis which is perpendicular to its direction of motion.

## Downforce

Downforce is a downwards thrust created by the aerodynamic characteristics of a car.

## Driving simulator

Driving simulators are used for entertainment as well as in training of driver's education courses taught in educational institutions and private businesses.

## Electronic stability control

Electronic stability control (ESC), also referred to as electronic stability program (ESP) or dynamic stability control (DSC), is a computerized technology that improves a vehicle's stability by detecting and reducing loss of traction (skidding).

## Engineering

Engineering is the creative application of science, mathematical methods, and empirical evidence to the innovation, design, construction, operation and maintenance of structures, machines, materials, devices, systems, processes, and organizations.

## Fishtailing

Fishtailing is a vehicle handling problem which occurs when the rear wheels lose traction, resulting in oversteer.

## Flight dynamics (fixed-wing aircraft)

Flight dynamics is the science of air vehicle orientation and control in three dimensions.

## Frequency response

Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system.

## Geometry

Geometry (from the γεωμετρία; geo- "earth", -metron "measurement") is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.

## Ground effect (cars)

In car design, ground effect is a series of aerodynamic effects which have been exploited to create downforce, particularly in racing cars.

## Ground pressure

Ground pressure is the pressure exerted on the ground by the tires or tracks of a motorized vehicle, and is one measure of its potential mobility, especially over soft ground.

## Hans B. Pacejka

Hans Bastiaan Pacejka (born 1934; died September 2017) was an expert in vehicle system dynamics and particularly in tire dynamics, fields in which his works are now standard references.

## Hunting oscillation

Hunting oscillation is a self-oscillation, usually unwanted, about an equilibrium.

## Lane

In the context of traffic control, a lane is part of a roadway (carriageway) that is designated for use by a single line of vehicles, to control and guide drivers and reduce traffic conflicts.

## Lift-off oversteer

Lift-off oversteer (also known as snap-oversteer, trailing-throttle oversteer, throttle off oversteer, or lift-throttle oversteer) is a form of oversteer in automobiles that occurs while cornering when closing the throttle causes a deceleration, causing the vertical load on the tires to shift from the rear to the front, in a process called weight transfer.

## Mass

Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied.

## Modelica

Modelica is an object-oriented, declarative, multi-domain modeling language for component-oriented modeling of complex systems, e.g., systems containing mechanical, electrical, electronic, hydraulic, thermal, control, electric power or process-oriented subcomponents.

## Moment of inertia

The moment of inertia, otherwise known as the angular mass or rotational inertia, of a rigid body is a tensor that determines the torque needed for a desired angular acceleration about a rotational axis; similar to how mass determines the force needed for a desired acceleration.

## Moose test

The evasive maneuver test (Swedish: Undanmanöverprov; colloquial: moose test or elk test; Swedish: Älgtest, German: Elchtest) is performed to determine how well a certain vehicle evades a suddenly appearing obstacle.

## MSC Software

MSC Software Corporation is an American software company based in Newport Beach, California, that specializes in simulation software.

## Multibody system

Multibody system is the study of the dynamic behavior of interconnected rigid or flexible bodies, each of which may undergo large translational and rotational displacements.

## Noise, vibration, and harshness

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.

## Pneumatic trail

Pneumatic trail or trail of the tire is a trail-like effect generated by compliant tires rolling on a hard surface and subject to side loads, as in a turn.

## Powertrain

In a motor vehicle, the term powertrain or powerplant describes the main components that generate power and deliver it to the road surface, water, or air.

Radial force variation or road force variation (RFV) is a property of a tire that affects steering, traction, braking and load support.

## Relaxation length

Relaxation length is a property of pneumatic tires that describes the delay between when a slip angle is introduced and when the cornering force reaches its steady-state value.

## Ride height

Ride height (also called ground clearance or simply clearance) is the amount of space between the base of an automobile tire and the lowest point (typically the axle); or, more properly, to the shortest distance between a flat, level surface, and the lowest part of a vehicle other than those parts designed to contact the ground (such as tires, tracks, skis, etc.). Ground clearance is measured with standard vehicle equipment, and for cars, is usually given with no cargo or passengers.

## Ride quality

Ride quality refers to a vehicle's effectiveness in insulating the occupants from undulations in the road surface (eg bumps or corrugations).

## Roll center

The roll center of a vehicle is the notional point at which the cornering forces in the suspension are reacted to the vehicle body.

## Roll moment

In a vehicle suspension, roll moment is the moment of inertia of the vehicle's sprung mass (the portion of its weight supported by the suspension).

## Rolling chassis

A rolling chassis is the chassis of a car or truck, assembled together with the engine and drivetrain, but without bodywork.

## Rolling resistance

Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface.

## SAE International

SAE International, initially established as the Society of Automotive Engineers, is a U.S.-based, globally active professional association and standards developing organization for engineering professionals in various industries.

The scrub radius is the distance in front view between the king pin axis and the center of the contact patch of the wheel, where both would theoretically touch the road.

## Self aligning torque

Self aligning torque, also known as aligning torque, aligning moment, SAT, or Mz, is the torque that a tire creates as it rolls along, which tends to steer it, i.e. rotate it around its vertical axis.

## Sim racing

Sim (simulated) racing is the collective term for computer software that attempts to accurately simulate auto racing, complete with real-world variables such as fuel usage, damage, tire wear and grip, and suspension settings.

## Simulation table

A simulation table is an automotive test system specifically designed for the high-frequency testing of vehicle components.

Simulink, developed by MathWorks, is a graphical programming environment for modeling, simulating and analyzing multidomain dynamical systems.

A skidpad or skidpan is a circular area of flat pavement used for various tests of a car's handling.

## Slip (vehicle dynamics)

In (automotive) vehicle dynamics, slip is the relative motion between a tire and the road surface it is moving on.

## Slip angle

In vehicle dynamics, slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing (i.e., the angle of the vector sum of wheel forward velocity v_x and lateral velocity v_y).

## Speed wobble

Wobble, shimmy, tank-slapper, speed wobble, and even death wobble are all words and phrases used to describe a quick (4&ndash;10 Hz) oscillation of primarily just the steerable wheel(s) of a vehicle.

## Sprung mass

In a vehicle with a suspension, such as an automobile, motorcycle or a tank, sprung mass (or sprung weight) is the portion of the vehicle's total mass that is supported above the suspension, including in most applications approximately half of the weight of the suspension itself.

## Steering

Steering is the collection of components, linkages, etc.

## Steering ratio

Steering ratio refers to the ratio between the turn of the steering wheel (in degrees) or handlebars and the turn of the wheels (in degrees).

## Suspension (vehicle)

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.

## Swept path analysis

Swept Path Analysis is the calculation and analysis of the movement and path of different parts of a vehicle when that vehicle is undertaking a turning maneuver.

## Tire

A tire (American English) or tyre (British English; see spelling differences) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface traveled over.

## Toe (automotive)

In automotive engineering, toe, also known as tracking, is the symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects.

## Tuned mass damper

A tuned mass damper, also known as a harmonic absorber or seismic damper, is a device mounted in structures to reduce the amplitude of mechanical vibrations.

## Understeer and oversteer

Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering.

## Unsprung mass

In a ground vehicle with a suspension, the unsprung mass (or the unsprung weight) is the mass of the suspension, wheels or tracks (as applicable), and other components directly connected to them, rather than supported by the suspension (the mass of the body and other components supported by the suspension is the sprung mass).

## Vehicular metrics

There are a broad range of metrics that denote the relative capabilities of various vehicles.

## Weight distribution

Weight distribution is the apportioning of weight within a vehicle, especially cars, airplanes, and trains.

## Weight transfer

Weight transfer and load transfer are two expressions used somewhat confusingly to describe two distinct effects: the change in load borne by different wheels of even perfectly rigid vehicles during acceleration, and the change in center of mass (CoM) location relative to the wheels because of suspension compliance or cargo shifting or sloshing.

## Wheelbase

In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels.

## Yaw (rotation)

A yaw rotation is a movement around the yaw axis of a rigid body that changes the direction it is pointing, to the left or right of its direction of motion.

## 4-poster

A 4-poster or four poster automotive test system is specifically designed for the testing of vehicles (cars, trucks).

## 7 post shaker

The 7 post shaker is a piece of test equipment used to perform technical analysis on race cars.

## References

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