NOISE, VIBRATION, HARSHNESS

Vibroacoustic comfort is one of the most critical properties in terms of customer response. Noise and vibration adversely affect the human body, increasing irritability and reducing attention.

All manufacturers are trying to make cars more comfortable and pleasant for the customer compared to cars of other brands. Acoustic comfort is one of the most critical criteria when choosing a car. The result is that competitive market requirements are always tougher than legal requirements. Therefore, all manufacturers are making remarkable efforts to win this fight – research is being conducted, large-scale laboratories and polygons are being built.

Perhaps one of the most striking examples is BMW's collaboration with composer Hans Zimmer, who develops special soundtracks for voicing the operation of the BMWi4 electric car engine.

The sources of noise radiation can be reduced to several simplified schemes of sound emitters, the main ones of which are:

• exciting alternating force;
• an elastic material medium through which vibrational energy propagates;
• the oscillating body itself (the sound-emitting surface of the oscillating body).

The exciting variable forces are:

• unbalanced forces and torques generated by the moving mechanisms of the internal combustion engine: crank, gas distribution, drives;
• work processes occurring in transmission units and chassis components;
• the micro profile of the road surface in contact with rolling tires.

The elastic medium is:

• elements (parts, assemblies) of the internal combustion engine mechanisms, transmission units, components of the PBX chassis;
• the elastic gas (air) medium itself, which fills the cavities of the elements of noise-generating systems: mufflers, intake, body cavities.

Sound-transmitting waveguides are formed from the generation zones to the open sound-emitting pipeline sections (the end section of the muffler, the section of the nozzle of the internal combustion engine air purifier, heater deflectors).

More detailed information about the impact of vehicle design on vibration and acoustic comfort is provided below.