Overview
Noise and vibration have a very large impact on the competitiveness of transportation vehicles, not only driven by the increasing customer demand for vibro-acoustic comfort, but also by the tightening of legal regulations regarding noise and vibration emissions and immissions. Since noise and vibration as functional performance attributes often conflict with other attributes, such as weight and CO2 emission, concurrent design and analysis procedures are required. Such processes involve multi-attribute optimisation and are facilitated by the use of Computer Aided Engineering (CAE) tools.
Also, there is an increasing trend towards virtual prototyping to reduce costs and development times. As a result, good CAE tools are essential in modern vehicle design. Ideally CAE tools would be applicable in the whole frequency range of interest, which is the audio-frequency range. In practice specific methods are applicable in a limited frequency region. A class of deterministic low frequency methods is both well developed and well established. High frequencies energy based methods are valuable, but less well-established. There is however, a mid-frequency gap in current modelling capabilities: too high for deterministic and too low for energy based tools. This is important, since it strongly affects product performance and competitiveness.
The lack of CAE tools for mid-frequency issues forms the target for this collaborative project. In this project a well balanced consortium of both academic and industrial partners will develop robust CAE tools, applicable for the analysis of mid-frequency noise and vibration problems. In a second stage, these tools will be applied on industrial problems, filling the currently existing gap. A third important aspect of the project is the dissemination of mid-frequency analysis and modelling skills throughout the EU engineering community to spread crucial knowledge and skills in strengthening EU transportation vehicle competitiveness.
Furthermore, the MID-MOD project set out to disseminate the innovative mid-frequency research results within the broad European engineering community. The dissemination was a crucial point in training a sufficient number of people with the proper vibroacoustic skills.
The project tried to develop innovative solutions for the modelling and simulation of vibro-acoustic transport problems in the mid-frequency range. In this way, the project filled crucial gaps in the state-of-the-art and state-of-the-use of vibro-acoustic modelling.
This involved a profound comparative study between five deterministic technologies which are currently most promising with respect to their applicability for industrial vibro-acoustic problems in the mid-frequency range. These deterministic technologies are:
- wave based method;
- fast multipole method;
- domain decomposition method;
- stabilised method and;
- higher order wave based integration schemes
The MID-MOD activities involve studies towards what is needed to lift these technologies out of their academic environment and to apply them to real-life engineering problems in the transportation industry. Problems, for which currently industrial CAE tools are lacking.
Another approach involves a similar comparative study, but instead of approaching the mid-frequency range from below using deterministic approaches, five high-frequency probabilistic methodologies are studied. These innovative methodologies were validated extensively with respect to component level, subsystem level and, finally, full vehicle level validations. It concerned the following methodologies:
- stochastic boundary elements;
- wave based finite elements;
- component modal approach;
- spectral finite elements and;
- point mobility approach.
The improvements following all these studies, became apparent in the following quantifiable project targets:
- reduction of solution times;
- enlargement of the applicable frequency range;
- increasing the prediction accuracy in the low-, mid- and high-frequency range: pursuing a 3 dB absolute accuracy;
- reduction of computational loads as well as memory and disk space requirements such that (networks of) conventional office desktop personal computers may be applied for numerical analysis;
- tools for Noise, Vibration and Harshness (NVH) evaluation to become available, not only for the expert analyst, but also for the design engineer to support early-design stage decisions based on a multi-attribute optimisation including NVH.
Funding
Results
Noise and vibration have a very large impact on the competitiveness of transportation vehicles. This is not only due to the increasing customer demand for vibro-acoustic comfort, but also due to the tightening of legal regulations regarding noise and vibration.
Ideally CAE tools would be applicable in the whole frequency range of interest (audio-frequency range). In practice, the methods are applicable in a limited frequency region. As a result, there is a 'frequency gap' in current modelling capabilities: too high for deterministic and too low for energy based tools.
A consortium of academic and industrial partners has developed robust CAE tools, applicable for the analysis of frequency noise and vibration problems. These tools fill the currently existing gap. Furthermore, the project has disseminated the developed frequency analysis and modelling skills throughout the EU engineering community. This strengthens EU transportation vehicle competitiveness.
Innovation aspects
Robust CAE tools have been developed, applicable for the analysis of frequency noise and vibration problems. These tools fill the currently existing gap.
Policy objectives
Innovating for the future (technology and behaviour): A European Transport Research and Innovation Policy