Denis Blanchet has developed a wide expertise in very different fields. He has learned over the years the benefit of teaming up with other experts when necessary to ensure a positive and fruitful outcome of any projects. His many international contacts developed over the years has made him a strong ally to have when dealing with difficult, unchartered VA applications. Our offering is therefore diverse and potential projects that differ from our existing experience are more than welcome.
Sound package design and optimization
Sound package design plays a crucial role in the passenger experience when driving a car. The sound package includes acoustic parts such as carpet, headliner, dash insulator, door covers, seats and so on. The design and optimization of the sound package has an impact on passenger comfort, total mass of the vehicle and therefore fuel consumption and finally cost. The proper physical representation of the acoustic parts in a simulation model allows for an optimization process to take place, whether manually or automatically using optimization algorithms. This process is typically done for combined loadcases such as structureborne, airborne and windborne noise and different operational conditions such as idle, various combinations of speeds and gear, coasting… The objective is to ensure interior SPL (Sound Pressure Level) is controlled over all vehicle operating conditions. See technical papers for examples [6,8,11,14,16,22,24,31,32,33,45,48].
Evaluate the benefits from using acoustic laminated glass
Glass design has brought us acoustic PVB (PolyVinyl Butyral) interlayer that significantly improves the acoustic transmission loss of glass panels by increasing overall damping of the composite layup of Glass-PVB-Glass. This has a positive impact at frequencies close to glass coincidence (between 2.5 and 4 kHz), a frequency range where the vehicle greenhouse exhibits a weak transmission loss. Whether you plan to use acoustic laminated glasses for the windshield and/or side glasses, dBVibroAcoustics can provide predictive models that will evaluate the effect of acoustic glasses on interior noise on any types of vehicles. See technical papers for examples [5,10].
Engine noise radiation
Even today, many manufacturers do not account for acoustics in their engine designs. They are satisfied with only monitoring surface vibration and assume that the radiated noise will be directly proportional to these vibration levels. As demonstrated in , the parameter that links surface vibration levels and acoustic radiated power is radiation efficiency. For the vibration levels to be directly proportional to noise radiated, the radiation efficiency has to be equal to one (1) for the whole frequency range. This is certainly not the case and can change by several orders of magnitude depending on the frequency of interest. With today’s available modelling methods such as Boundary Element Method (BEM) and Fast-Multipole BEM (FMM-BEM), it is possible to efficiently compute the radiated noise from an engine and determine the benefits or drawbacks of engine design changes virtually. For an illustration of these concepts, see tech papers .
Turbulent flow generated in the surrounding of the vehicle glasses is of great importance for full vehicle acoustics design team because of the potential noise that can migrate to the interior of the vehicle. Understanding the physical phenomena involved in the coupling of the turbulences with the glass panels allows for the creation of an accurate predictive model of windnoise. This simulation model can be quite useful in the design of quieter vehicle by impacting the source of turbulences by modifying the shape of side mirror, A-Pillar, wheelhouse or the side glass offset. Quieter designs can also be achieved by modifying the path energy takes to reach the interior of the vehicle. In this case changing the properties of the glasses (acoustics glasses [5,10]) or the mounting strategy. See technical papers for more details [18,29,30,34,35,39,42,44,46,47,50,51,52] and  for a review of the latest results obtained with the “German Working Group on Windnoise”.
Component Transmission Loss (floor, dash, cockpit)
Transmission Loss is a key quantity when it comes to characterizing the ability of a structure to block noise. It also has the benefit, when done properly, of being independent of the room in which measurements were taken. In the simulation world, it is possible to compute transmission loss for full frequency analysis in a reasonably short time even with deterministic approaches. This provides a very accurate simulation model that can be used to design better components. See  for an example of a cockpit module TL exercise where a SEA model is put to the test to see if it can track drastic design changes. See also an academic example of a composite layup TL validation case . Finally, one of the key topic of transmission testing and simulation if the presence of leaks in the structure. Even a very small opening can have a significant detrimental effect on transmission loss and should be accounted for in the simulation to obtain an accurate predictive simulation model. See following technical papers for application on automotive structures [10,14,15].
Understanding break squeal noise is key in designing quieter breaking systems. Most manufacturers do understand the non-linear simulation process needed to predict complex vibration field on the surface of the brake assembly. They can also predict complex Eigen modes and from there determine if modes are stable or not. The unstable modes are the ones more likely to radiate noise. It is possible to predict the radiated noise at these frequencies by coupling the complex velocity field to a BEM computation. Radiation efficiency and radiated noise can be ranked for various frequencies and radiation pattern can be visualized and used as sources for full vehicle analysis. Since work done is still confidential, no technical papers are yet available to illustrate this topic.
Several simulation methods have proven muffler noise can be predicted accurately. Deterministic solutions such as FEM and BEM can be used to predict low frequency noise while SEA can be used for high frequency noise radiation from the muffler shell. Both structureborne and airborne sources can be used as well as flow induced noise and vibration. dBVibroAcoustics can help in the design of innovative solution by using predictive simulation models.
eMobility warning signal
With the increased popularity of electric vehicle, safety of pedestrians walking in city streets is more critical than ever. Slow approaching vehicles are difficult to hear and car manufacturer need to design warning signals that will allow pedestrian to safely walk around. Various strategies can be adopted to warn pedestrians of a vehicle approaching and several simulation methods can help determine if these strategies will generate the desired amount of noise at a particular location before any prototypes are available. dBVibroAcoustics can help in the design of innovative solution by using predictive simulation models.