5 Tier Levels of Mvoid® Methodology for a Complete Virtual Product Development Environment
March 27, 2015:
The concept and design of the components as well as the evaluation of the systems with modern simulation methods in the early phase of product development are becoming increasingly important, not ultimately thanks to shorter development cycles and the increasing expansion of model ranges.
Konzept-X (Mvoid) has developed a process model to simulate the complete vehicle acoustics using vehicles CAD. It is not just limited to graphical analysis. You can literally listen to the virtual audio system. Sound characteristics are virtually measurable and assessable and can be optimized directly on the virtual model. Some of you surely know the model. It is known on the market by the name Mvoid® (Multidisciplinary virtually optimized industrial design).
Mvoid® couples five different Tier levels for multidisciplinary models. Only when all five levels are considered, a complete virtual product development environment can be created, which allows a realistic listening environment of the virtual audio system.
Tier level 1: Multiphysical modeling of loudspeakers
Within the first Tier level the point is to create the multi-physical modeling of the speakers. It is the most important challenge to analyze the different physical domains, as each domain interacts bi-directionally with each other. Electromagnetism, mechanics, acoustics, and sometimes thermal transfer and fluid dynamics are taken into account. Besides, we also have to deal with path dependent dynamic effects and nonlinearities (including instabilities) in each domain. Hence, Lumped parameter models, finite element models and boundary element models are used for multi-physics simulation.
Tier 2 level: Multiphysical loudspeaker model attached to enclosure
In order to achieve an outstanding sound performance not only the quality of the speakers is important. Of particular importance is the mechanical and acoustic integration of the loudspeakers in the vehicle. For developers, the space requirements of speakers can be particularly challenging. In the past, this integration was evaluated mainly with real prototypes at a late stage of development. It took a lot of time and money and also bore a risk in the progress of the project.
By using CAE-based simulation tools the speaker integration can be optimized already in the design phase. As a result, errors can be avoided, for example spurious oscillations of enclosures and structural parts. Besides, complete new ways of integration can be taken into account. For example the use of cavities of the vehicle structure as resonance volume for speakers, because loudspeakers require an enclosure as resonance volume in order to reproduce low frequencies. By limitations of available space these enclosures often have a complex geometry and an important influence on the sound. Consequently, in Tier level two the previously designed multiphysics model of the speaker has to be extended, the enclosures have to be integrated and provided with mechanical and acoustic characters.
Tier 3 level: Full system model
In the next step, the car cabin with its mechanical and acoustic characters is to be integrated into the simulation model. The car cabin has an important impact on the perception of the sound, too. Due to the mix of materials, like different kinds of leather, plastic and textile a hybrid approach is used. Because: The coupled multiphysics model alone will not automatically lead to realistic simulations. The various materials with totally different behavior and different joining techniques require detailed descriptions of the material properties in the electrical and structural domain. Thus a key aspect here are material measurement procedures specifically designed to measure electrical and mechanical parameters.
Multiphysical analysis car cabin and loudspeaker with enclosure.
Different colors show that the acoustic pressure is particularly high respectively give guidance in eliminating problems.
Within the multiphysical simulation model the distribution of the sound can be determined right into the backmost corner. All factors that affect the sound in the interior, however minimal, are taken into account.
Already at this stage we can hear the virtual audio system on our computer by means of a special reproduction technique, enabling us to improve the sound. The optimum position of the speakers can be analyzed virtually and corresponding components can be selected.
Tier 4 level: Virtual tuning of audio systems
In the perception and evaluation of a sound different psychoacoustic characteristics and properties are of importance. Through careful virtual tuning irregularities and resonances in frequency response are compensated. Extensive tests and measurements are carried out. The frequency response of all channels must be coordinated. For all seats, run-time differences from the various loudspeakers to the listener and the volume level are regulated to produce an outstanding sound performance.
Tier 5 level: Auralization of Audio systems
After extensive tests and measurements with modern simulation techniques, the virtual audio system must finally undergo the analysis by human ear. These listening tests are necessary to finally evaluate the audio performance, especially in terms of spatial reproduction.
When all five Mvoid®tier levels are being applied, we can refer to a complete virtual product development environment. The result is a virtual mock-up to be used from the concept development of the next generation of vehicles till SOP. The final car profile, equipment and material properties can change during development phase. The virtual model enables it, to analyze and optimize the various system architectures and system content as well as positions of speakers during the whole development cycle.
Konzept-X (Mvoid) is continuously improving the accuracy and efficiency of multiphysical calculations. Thus we are currently working to capture non-linear models and their behavior on different levels, to identify even more possible disruptions of the listening experience. In future work we will add more and more physical effects, e.g. road noise or thermal effects.