Virtual reality main topic of Daimler-Benz CAE gathering

Munich, 14-10 -1996 The CAE engineers of the Daimler-Benz Group met on October 7 and 8 for the fourth time to discuss and exchange their experiences in different engineering fields. This is one of the platforms in the Daimler-Benz Group, where synergy really takes place. It was organised and sponsored by debis Systemhaus Computer Communication Services (CCS). This year the number of participants grew to about 160, including engineers from the Daimler-Benz Research, automotive (Mercedes-Benz), aerospace (DASA and DASA Airbus), software houses and partners/sub-contractors of Daimler-Benz in the CAE environment. They discussed Virtual techniques, CAE hardware and software developments. Some key presentations are covered elsewhere in this issue.

"The real importance of HPCN is on the software side. There is a wide gap between the possibilities of the hardware and the effective use of these machines when using complex application packages. This gap has to be closed by modifications in the software. Some of today's funding programs are going into this direction. We, the industry, need these machines to shorten the development cycle and to improve the quality of the products." noted Dr. Peter-Alfons Haas, Head of CCS Southwest Germany in his welcome address, summarising experiences from visits to all the major vendors.

Free supercomputer time for innovative projects is, according to Haase, a new idea to accelerate the use of HPC technology within Daimler-Benz. A commission examines projects and allocates a computing time contingency for them, if the approach seems successful.

The machines at the HWW supercomputer centre in Stuttgart can be used by industry for a certain percentage of time: the NEC SX-4 32 processors, the Crays T3E 512 processors, T90 4 processors, C90 4 processors and J90 8 processors are all available to industry. Dr. Haas offered all participants the chance to use these brand new supercomputers for their industrial research projects.

Debis Systemhaus plans to sell computing time and services not only to big companies . It also wants to support small and medium enterprises in using HPC technology in order to improve development and product cycle time.

CAE and simulation in the development process of a car

P. Schneider and A. Strobel, Daimler-Benz Ulm, reported on the use of digital mock-ups. In the digital model, using CAD data (CATIA) they look for the best way of cabling . The results are then transferred back to CATIA. Then you can move from the simulation to the physical model. It is important to integrate all of the data for the different parts that are available. They presented a circle in which design, development, production and sales access the same product database. Sometimes this technology is called CALS (Continuous Acquisition and Life Cycle Support).

Another view of the same topic was highlighted by Alfred Katzenbach from Mercedes-Benz. Digital mock-ups result in earlier final stages for the development process because the presentation of the new product looks very "real". The engineer, designer and salesman get a good impression of the car and - based on this information and visualisation - can decide on the structure. The physical model will be built at a later stage of the process.

The prototype is of sufficient quality to be presented to the customer. All of these modern techniques discussed during this CAE-Forum, result in a reduction of the development process for a new Mercedes-Benz S-class from 120 months to 50 months.

Some simulation examples

A physical model of the dynamics of the total system has been built, showing the interplay between the tires, driving shaft and gears. Thus not only single parts are simulated - as in the past - but the influence of the whole system . The results have been verified by real road tests. As tools were missing the team developed a simulation environment for this application.

The requirements of computing time are a factor of 15 compared to real-time. The noise a truck produces depends heavily on the gearbox. New legal constraints now require detailed research of the noise sources inside it. This is an important factor in the construction of the gearbox, with numerical results now having an influence on this process. A hybrid experimental and numerical model was used to compute the resonance and noise of a car.

In the first step CAD models and finite element analysis are used to compute noise. At this stage, assessment of the results is coarse but the modifications can be realised easily. Measurement at a later stage is precise but changes are difficult and costly.

Simulation of electromagnetic compatibility now becomes more and more important, as about 10 to 20% of the costs of a car belong to the electronics. So the simulation and the influence of electromagnetics was discussed for parts and their locations, components and the whole system as well as the influence on the car, the environment and human being.

Because the engineers in the Daimler-Benz group use different FEM application program packages, the vendors presented new developments, including parallelisation work in the EUROPORT project. In NASTRAN about 85% to 95% of the elapsed time is spent in the solver. In EUROPORT this kernel is optimised and parallelised, with an 8 processor IBM SP2 performing the same as a Cray T90 or Cray Y-MP, depending on the problem type to be solved.

Uwe Harms