Jürgen Kohler, Senior Manager, NVH CAE & Vehicle Concepts, Mercedes-Benz Cars Development, Daimler

CAE has become an indispensable part of modern development processes and an integral component alongside design, testing and trials. The challenge of designing ever more complex vehicles efficiently, to a high degree of maturity over an acceptable period of time and without the need for expensive trial phases can be achieved only through the intensive use of simulation tools. The digital prototype has been integral to the work of Mercedes-Benz Cars Development for more than ten years.

Since the launch of the digital prototype, each vehicle has been digitally predesigned and each component specifically optimized by computer in terms of functional requirements such as active and passive safety as well as driving, acoustic and thermal comfort, to name just a few. Such aspects frequently entail trade-offs not only among each other, but also with other aspects such as weight, cost and manufacturability. In the quest for the optimum “brand-appropriate” compromise, the digital prototype has proven to be a major boon. This is evident in the high number of computing jobs that are performed not only to assess a wide range of design variants, but also to make vehicles immune to manufacturing variations. Further methodical and numerical refinement has seen a constant expansion of the application area of simulation tools, a process that remains ongoing.

Various computation models and simulation methods are used depending on the type and complexity of the task. To achieve the greatest possible informative value, state-of-the-art computing tools are needed – in some cases, multiple tools that interact with each other in co-simulation. In addition, computing models are constantly getting bigger because they now also map localized details geometrically and physically.

To ensure that this does not impact the turnaround times in day-to-day development work, rapid numerical algorithms and cost-optimized high-performance computers are deployed, that can keep pace with this trend and are designed for high-capacity computing. This is why Mercedes-Benz Cars Development uses locally placed high-capacity computer clusters. Their efficient and failsafe operation ensures a reliable vehicle development process.

Jürgen Kohler studied Aerospace Engineering at the University of Stuttgart. In 1992 he started his career at the Mercedes Benz AG and became Manager of Crash-Simulation in 1997. From 2001 to 2005 he was Senior Manager for CAE Passive Safety, Durability and NVH, from 2006 to 2010 for CAE Passive Safety, Durability and Stiffness CAE and Test. In 2011 he took over responsibility for NVH CAE and Vehicle Concepts in the Mercedes-Benz Cars Development. Jürgen Kohler is also a member of the Board of Automotive Simulation Centre Stuttgart (ASCS e. V.) and the Chairman of the PRACE Industrial Advisory Committee.

Interview : Why Mercedes-Benz uses HPC

ISC: How long has Mercedes-Benz been employing high-performance computing for designing vehicles? And what motivated Daimler to turn to CAE and HPC-based simulations?
Kohler: Mercedes-Benz first started with its simulation activities in research and development back in the 1960s. At first, programs for the industrial application of the finite element method were self-developed in-house to support, for example, the elastic-static design of the vehicle structure by computational means. Later on the company switched to the commercial FE program, NASTRAN when it was first offered on the market. There are various versions available today and we use NX NASTRAN. So with the use of more detailed models to consider all relevant design details, the access to HPC became compulsory for us. It was also equally necessary to get the analyses results back in an “acceptable” amount of time. In the past, we had to wait several days; today we are able to obtain results overnight.

ISC: How has the use of simulations changed the development and manufacturing of automobiles?
Kohler: Our so called “Digital Prototype” has been integral to the work of Mercedes-Benz Cars Development for over a decade now. The company realized early on that complex vehicle design can only be achieved through the intensive use of simulation tools in closest interaction with precise and complementary testing. Today CAE has become an indispensable part of modern development processes for us and an integral component alongside design, testing, and trials. This was undoubtedly triggered by the challenge of designing ever-more complex vehicles to a high degree of maturity over an acceptable period of time, and without the need for expensive trial phases.

ISC: How powerful are the compute clusters that Mercedes-Benz uses for vehicle development?
Kohler: The computing models are constantly getting more complex and bigger because they now also map localized details geometrically and physically. To ensure that this does not impact the turnaround times in day-to-day development work, cost-optimized high-performance computers are deployed, which can keep pace with these demands. This is why Mercedes-Benz Cars Development uses high-capacity compute clusters, consisting of a number of multi-CPU machines with sufficient RAM and capacity. For example, when simulating NVH – noise, vibration, and harshness – we can run more than 400 demanding full-vehicle jobs per day, where one run involves calculating 8,000 modes from a 30 MDOF matrix.