P.O. Sturesson, Driving Dynamics & Noise & Vibration Centre – Volvo Car Group.
Automotive NVH – Methodology for Future Innovative Product Development
The automotive market is subject to not only a highly competitive environment but also facing introduction of many new technologies spanning from pure electric propulsion systems to advanced driver assistance systems. All of these new technologies together with continuously increasing customer expectations give rise to challenges in the automotive OEM product development as they require a high rate of innovation and development. Additional complexity in terms of new legal regulations, such as vehicle safety, CO2 and noise emission reduction, which often are contradicting, needs consideration during the product development. An efficient and innovative product development organisation yields significant competitive advantages as more product can be put to the market faster for a given cost and time.
The refinement of noise, vibration and harshness (NVH) is one the most important tasks in the premium and luxury automotive segments during the vehicle development process. It strongly influences the overall perception of the vehicle together with other attributes such as styling, digital user experience, performance & drivability and vehicle dynamics.
The introduction of new technologies, such as electrification and software-controlled systems, result in numerous challenges with respect to NVH requiring cost and weight efficient countermeasures coupled with new simulation and test methods. Consideration to secondary effects caused by trade-off with other attributes is also critical and requires cross-attribute optimisation. Traditional target setting and down-cascading processes through benchmarking is not readily applied. Simulation and test methods as well as engineering system solutions derived during the product development relies strongly on experiences from previous programs through closed loop learning. The high rate of innovation with a smaller knowledge basis results in higher risk of failure as many issues may not be foreseen. Therefore, it is important to execute advanced research projects up-front of the ordinary product development projects to address all new concepts and technologies. Focus on closing critical knowledge gaps early in the product development is required. Knowledge gaps may not only be related to the physics of the new technologies but also to customer preferences. Strategies like application of NVH simulator technology and systems engineering and synthesis early in the product development phase should support a robust decision making. The need to derive noise and vibration characteristics for critical systems, such as interior sound pressure level or radiated sound power, for different use cases are examples of necessary strategies in future automotive development. In this paper, different application cases from development of new technologies will be discussed.
E. Balmes, Ecole Nationale Supérieure d’Arts et Métiers – Laboratoire Procédés et Ingénierie en Mécanique et Matériaux (PIMM).
Shapes & DOF: on the use of modal concepts in the context of parametric non-linear studies
Physical responses tend to lie within restricted subspaces even for parametric problems. For a given subspace, the choice of a basis defines Degree Of Freedom (DOF) and this choice may give interesting meaning to the associated amplitudes. Classical modal analysis builds subspaces combining modeshapes and static responses. Parametric loads for non-linear, damped, variable, ... structures are discussed to extend the theory and illustrated for test and simulation cases. Challenges in shape extraction and basis generation techniques are then detailed. Introducing the ability to manipulate models with variable junction properties, component material and geometry, load and operating conditions, ... opens new questions on the quantification and tracking of changes and objectives throughout design exploration. The definition of a reference linear system and the use of global and/or local modal DOF are shown to provide an interesting perspective.