Optimized lightweight design taking into account the vibro-acoustic behavior of the vehicle structure
Optimise lightweight construction, comfort and economy in the design phase
The vibro-acoustic behaviour of vehicles has become increasingly important in recent years and is a decisive factor in the purchasing decision of customers. There are various sources of noise in the vehicle (engine, auxiliary units, tire road noise and airflow), which often have a disturbing character, but are also sometimes desired as acoustic feedback or are even perceived as a characteristic quality feature of a vehicle (e.g. engine sound). Therefore the evaluation and influencing of vehicle acoustics and vehicle vibration behaviour in early phases of the development process is becoming more and more important.
At the same time, greenhouse gas emissions and resource consumption are to be reduced. A significant reduction of the energy demand and thus the emissions of vehicles can be achieved by reducing the vehicle mass. The use of high-strength steels, light metals and fibre composites as well as associated design principles is therefore an important trend in the automotive industry. However, these lightweight construction concepts have a strong influence on the vibro-acoustic behavior of the vehicle. They "have a decisive influence on the transmission behavior of the vehicle structure, such as global and local body stiffnesses, mass distributions and lightweight sound insulation and damping".
Currently, NVH challenges are only considered after the majority of the vehicle structure has already been defined or in the immediate run-up to the actual market launch. In these late development phases, vibration reduction can usually only be achieved by passive measures. These usually do not represent the optimum weight aimed for by utilizing lightweight structures, and are associated with high additional costs. Adaptronic systems can resolve the conflict between the requirements for lightweight construction and good acoustic behaviour, but are much more complex in their design and development than passive solutions.
At the beginning of the research project, no simulation tool was known which would efficiently enable a holistic consideration of various adap-tronic and passive measures as well as new materials under the aspects of lightweight construction, vibro-acoustic behaviour and cost-effectiveness. The aim of the project was therefore to provide a user-friendly simulation and modelling procedure for the overall vehicle simulation of adaptronic and passive measures in one software package. This software will be used in early development phases and will allow a targeted influencing of the vibration and acoustic behaviour by integrating passive and adaptronic measures as well as new materials. Due to the modularity of the simulation tool and the integration of partial models from different areas, vehicles can be analyzed and improved acoustically and vibrationally throughout the entire development process. This improves weight, space utilization, development times and costs. This holistic approach thus leads to a weight reduction and improved driving comfort within a given cost framework.
Within the scope of the project, exemplary measures for influencing interior comfort were derived from a demonstration vehicle. One example is active engine mounts, which influence the vibrations generated by the engine by active counterforces even before the vibrations are transfered to the body, thus enabling the vibration behavior in the passenger compartment to be optimized. The use of the control systems is an integral part of the active systems. These measures were simulated in the entire vehicle and implemented in the demonstration vehicle.
One of the central tasks of the Institute for Automotive Engineering was the successive vibro-acoustic measurement of the demonstration vehicle in the various modification stages. These measurements were carried out in close cooperation with the project partner ZF. Based on the data obtained, a measure evaluation was carried out at full vehicle level. In addition, the data were used for the development and validation of the simulation tool and the partial models. A further component of the ika's tasks was the development, preparation and execution of principle tests for the validation of the relevant partial models and the identified measures at component level.
no Person assigned: I2649
10/2016 – 09/2019
LBF, Daimler, ZF, Boge, Novicos, Simetris, Open LS