Automotive - Development, Vibration Analysis & Testing

Aeroacoustics deals with the noise caused by aerodynamic flow. Turbulent flow as well as flow through and around structures creates vibrations on components. These vibrations, in turn, are responsible for the generation and emission of sound waves, some of which people perceive as unpleasant. Ever stricter emission regulations also increase the need for noise-reducing designs.

Noise reduction is particularly important in the aerospace and automotive industries. Examples of noise include, engine noises on aircraft or wind noises on motor vehicles and high-speed trains. As other sounds of noise are more and more reduced or eliminated, as is apparent from the replacement of internal combustion engines in motor vehicles by electric drives, flow induced noise is perceived as more present and disruptive.

The airborne sound  is measured by microphones or entire arrays of microphones. However, when it comes to identifying the possible sound sources, measurement methods with better spatial resolution, such as scanning laser Doppler vibrometry, are required.

With the Optomet laser scanning vibrometers, both small structures and entire vehicles can be examined without contact and with high accuracy. The user-friendly OptoSCAN software enables the measurement to be carried out quickly and offers a wide range of meaningful analysis  and clear two-dimensional and animated displays for this task. For example, the correlation of the forms of vibration with the frequencies recorded in airborne noise can be used to draw important conclusions about the location and the type of sound generation, and suitable design measures for noise suppression can be taken.

The infrared laser technology (SWIR) of the Optomet scanning vibrometer produces a sufficient signal level for a reliable vibration measurement even at larger measuring distances of more than 10 meters. Even dark or reflective curved measuring surfaces can be measured without a reflection-enhancing treatment. Measurements through thick glass surfaces between vibrometer and measurement object are also possible without impairments.

Modern cars have many electric drives built in, some of which are in the direct area of perception of the occupants of the car, such as electric windows, electric sunroof, servo motors for outside mirrors, wiper motor or seat adjusters. Other drives operate without being perceived directly, such as fuel and coolant pumps or blower motors.

Beyond their desired function, these drives an also be a source of objectionable noise. Such extraneous noise can become clearly audible, especially in electric or hybrid vehicles where the combustion engine as one of the main sources of noise is eliminated.

Laser vibrometers from Optomet are ideal in assisting design and test engineers in localizing, visualizing, quantifying and eliminating such sources of undesirable noise. 
 

Automotive Noise, Vibration and Harshness (NVH) is the study and modification of the noise and vibration characteristics of passenger vehicles.  Generally, a vehicles NVH is modified to eliminate or reduce unwanted sound or vibration which improves occupant comfort and perception of vehicle quality.  NVH tests are used to localize sound sources and eliminate them which provides occupants the best experience possible.

Laser scanning vibrometers from Optomet with their high spatial resolution and their high signal-to-noise ratio on any surface are particularly suitable for locating the sources of sound and vibration. With the simple and intuitive software for the measurement process, the meaningful 3D visualization of the data and the fast automated scanning process, product surfaces can be examined in a very short time.

The numerous options for displaying and exporting the measurement data facilitate communication with colleagues. Based on the results, engineers can, for example, rethink component connections or geometries and increase damping at suitable points.

In the age of tablets and smartphones, we have long become used to swiping instead of typing. However, many users find it difficult to type on virtual keyboards because they cannot see through their fingertip which point on the touch screen is being touched.

Safety issues arise when touch-sensitive displays are used during the operation of a vehicle. One solution is haptic displays which make keys and slide controls physically perceptible on the display. They provide tactile feedback to a user’s finger during the execution of his or her commands without the need to look at the screen.

Optomet laser Doppler vibrometers are indispensable tools during the development of such haptic displays as well as for their quality assurance in production.