Truck manufacturer Scania (based in Sweden) produces more than 50 000 trucks a year. While competitors' trucks typically have around 25 000 components, Catia has helped Scania to almost halve that number, and further cuts are anticipated. Now the company is looking to use more simulations throughout the entire development process to reduce cycle time as well as improve truck performance and maintenance.

Catia is the main CAD/CAM system at Scania, with over 180 licences being used for the design of all truck systems and components. It has proved a good return on investment through the use of new tools like Catia Generative Part Stress Analysis in the Engine and Chassis departments, and supporting the re-engineering of the development process.

In an ongoing quest for excellence Scania is now encouraging designers, analysts and test teams to work closely together throughout the development phase. This co-operative approach enables Scania to be more reactive to the market while enriching the product knowledge gleaned from both physical and virtual prototypes.

Chassis: better weight control

For chassis frame mounted components like brackets, Scania uses Catia Generative Parts Stress (GPS) to perform speedy fatigue analysis. Loads matching those recorded during physical tests are introduced as inputs in Catia GPS for static simulations. Internal methodology and close cooperation between designers and analysts give a high degree of confidence in simulation results so that critical decisions can be made at an earlier stage in the design cycle.

CAE engineer Claes Erixon explains, "With the use of Catia GPS, we have increased both the number of components analysed, as well as the total number of analyses performed. Ease of use of GPS is essential - designers do not have to worry about which command to run." Specialists who provide customised training for Scania chassis parts give designers basic internal education in structural analysis. Currently, more than 60 people are trained to use Catia GPS, enabling all project members to effectively speak the same language. Another benefit of this kind of cooperative approach is that it frees up specialists to concentrate on advanced and non-linear problems.

For example, specialists can run static simulations on the chassis frame with the Catia Elfini solver and also run Abaqus computations using the direct Catia-Abaqus interface.

Optimising engine valve systems

Truck engines are continually subjected to high levels of stress, and with low engine weight and durability high on the customer agenda, Scania designers and engineers need to understand the structural behaviour of key components in a dynamic mode of operation. This, coupled with the need to shorten cycle times, led Scania to use the integrated analysis solutions within Catia to avoid time and effort wasted transferring data between CAD and CAE systems. In a further bid to reduce engine weight, the manufacturer will optimise the complete structure by introducing specific tools within the Catia CAD environment.

In the engine department, CAE engineer Thomas Timren describes how Catia GPS is used by both designers and analysts. "For valve design, Catia GPS is a performance tool that allows our engineers to benefit from contact simulations. We can now simulate with adaptive capabilities in critical areas of the valve design.

"Results obtained via Catia Elfini simulations are excellent compared to those from tests performed on well-known parts. The objective is to be able to run iterations with the computer and use test results simply for verification."

The Catia Elfini solver enables dynamic simulations to be performed to assess modal frequencies and to determine acceptable frequencies of the valve. It has made quite a difference, according to CAE engineer Thor Brenden. The total number of iterations they are able to perform on a component has increased from 10 to 20. Over the last five years they have been able to reduce the time needed to mesh an engine block from six months to two days, thanks to the new meshing techniques (free mesh vs mapped mesh), to better design preparation and also to the close integration between design and analysis.

Future Catia analysis

To allow designers to get complementary information about modal frequencies early in the development cycle, and to determine other critical parameters, Scania plans to add Catia Generative Part Dynamic. Another step will be to couple other types of simulations, like fatigue, dynamic and combustion studies, with initial computations carried out on Catia.

For more information contact Igal Filipovski, CDC, 011 786 3516, igal@cdcza.co.za, www.cdcza.co.za