Tire-road noise affects both the exterior as well as the interior noise of a vehicle. The exterior noise in particular has become increasingly important since the 1970s, as it has been possible to significantly reduce the equally-relevant drivetrain noise during this period. With the electrification of the drivetrain and the associated further reduction of the powertrain noise, optimization in the field of tire-road noise becomes even more important.

The exterior noise component can be determined from far-field measurements on test tracks, however, also by using a tire-road noise trailer. Its contribution to the interior noise can be determined by means of a test bench, developed at FKFS, separately.

For the determination of the rolling noise in the vehicle interior, the servo-hydraulic 4-post test bench at FKFS is suitable.

This field is concerned with inner-engine operations regarding the noise and vibration behavior of combustion engines and electric motors, including the associated drivetrain components.

This is based on the use of the very latest test facilities as well as problem-focused analysis and calculation procedures.

Focus Areas

• Investigation and optimization of noise excitation due to combustion and mechanisms e.g. valve train, pistons, crankshaft bearing
• Combustion noise optimization based on engine-specific structural insulation, taking into consideration conflicts arising from consumption and emissions targets
• Excitation and guidance of structure-borne noise
• Modal and operational vibration analysis
• Quantification (level, psychoacoustic parameters) and subjective evaluation of engine noise emissions

Instrumentation and Analytic Technology

• Air and structure-borne noise instrumentation
  (microphones, artificial head, accelerometer, scanning laser vibrometer)
• High and low-pressure indication
• Contactless measurement (eddy current principle) of small distances
  (crankshaft displacement, piston transverse motion, flywheel wobble, movements in the valve train)
• Rotational irregularity measurement and torsional vibration analysis
• Simultaneous, digital measurement signal recording, time and crank angle-dependent,
  > 60 channels
• Conventional and special procedures for digital signal analysis

It is not only in premium class vehicles that squeak and rattle noise quickly leads to the customer rating the vehicle negatively. Customers expect an adequate acoustic atmosphere in the vehicle and are increasingly discerning in this regard.

Therefore, it is essential to avoid clattering windscreen wipers as well as components which rattle, creak or squeak. Also, operational and functional sounds have to be designed in such a way that they match customer wishes as closely as possible.

Squeak and rattle noise can be measured in a clearly defined environment. For example, FKFS can use its own servo-hydraulic 4-post test bench to excite the vehicle for this purpose. FKFS`s anechoic acoustic test chamber is particularly suited to investigating operational and functional sounds.