NVH Target Cascading from Customer Interface to Vehicle Subsystems 2013-01-1980
The definition of vehicle and powertrain level targets is one of the first tasks toward establishing where a vehicle will reside with respect to the current or future state of industry. Though development of sound quality metrics is ongoing to better correlate objective data with subjective assessments, target setting at the vehicle level is relatively straightforward. However, realization of these targets depends on effective cascading to system and component levels. Often, component level targets are derived based on experience from earlier development programs, or based on selected characteristics observed during component level benchmarking.
An approach is presented here to complement current strategies for component level target definition. This approach involves a systematic concept for definition of component NVH targets based on desired vehicle level performance and a consequent target break down. The target break down is performed using a TPA method in combination with knowledge about the typical behavior of excitations and transfer functions. Using this approach, target lines are derived for vehicle components such as powertrain, intake and exhaust systems. These targets are then cascaded down further to individual paths and split into targets for excitations and transfer functions (e.g., powertrain mount vibration and vibro-acoustic transfer paths of the vehicle body). This systematic target cascading process is helpful in developing a balance between NVH performance and other development goals.