Fundamentally, vehicles are assemblies of subsystems or modules; engine, tyres, dashboard, steering system, body structure, wheel suspensions, etc. These modules are developed in parallel at multiple locations and often for more than one vehicle. On top of this, the integration of modules in a complete vehicle is also becoming a parallel rather than sequential development activity. This has a strong impact on vehicle NVH development.
The noise and vibration (NVH) quality of a vehicle will become apparant not too long before its planned production start, on the first fully trimmed and equipped prototype vehicles. Under normal costs and product release pressure, this does not leave much scope for further NVH development. The obtainable NVH quality therefore relies strongly on the specification and assesment process of the subsystems as well as on the early part of the integration process.
Within the context of this paper, a single component, smaller assemblies of components, up to major functional groups of the complete vehicle will all be called a module or subsystem.
Recent improvements of substructuring and transfer path analysis techniques can contribute significantly to the reliability and practicality of modular NVH assessment and development. This does not only cover the individual subsystem design, but also the assessment of proposed packaging and subsystem interfacing solutions.
