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The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. [1] [2] [3] The Doppler effect is named after the physicist Christian Doppler, who described the phenomenon in 1842.
Automotive aerodynamics is the study of the aerodynamics of road vehicles. Its main goals are reducing drag and wind noise, minimizing noise emission, and preventing undesired lift forces and other causes of aerodynamic instability at high speeds.
The first vibrational mode corresponds to the lowest natural frequency. Higher modes of vibration correspond to higher natural frequencies. Often when considering rotating shafts, only the first natural frequency is needed. There are two main methods used to calculate critical speed—the Rayleigh–Ritz method and Dunkerley's method. Both ...
Torsional vibrations can lead to seat vibrations or noise at certain speeds. Both reduce the comfort. In ideal power generation (or transmission) systems using rotating parts, the torques applied or reacted are "smooth" leading to constant speeds, and the rotating plane where the power is generated (input) and the plane it is taken out (output ...
Vibration (from Latin vibrāre 'to shake') is a mechanical phenomenon whereby oscillations occur about an equilibrium point.Vibration may be deterministic if the oscillations can be characterised precisely (e.g. the periodic motion of a pendulum), or random if the oscillations can only be analysed statistically (e.g. the movement of a tire on a gravel road).
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 ...
In a car, for example, such an engine with cylinders larger than about 500 cc/30 cuin [citation needed] (depending on a variety of factors) requires balance shafts to eliminate undesirable vibration. These take the form of a pair of balance shafts that rotate in opposite directions at twice engine speed, known as Lanchester shafts, after the ...
Speed wobble (also known as shimmy, tank-slapper, [1] or death wobble) is a rapid side-to-side shaking of a vehicle's wheel(s) that occurs at high speeds and can lead to loss of control. It presents as a quick (4–10 Hz) oscillation of primarily the steerable wheel(s), and is caused by a combination of factors, including initial disturbances ...