ALGOR FEA & DESIGN SOFTWARE HELPS CHRYSLER REFINE CAR PARTS

A Compaq DeskPro 386/25 was used to analyze this and three other proposed designs of a future Chrysler vehicle crossmember. The largest model contained 502 nodes and 518 elements.

Engineers with Chrysler are using the Algor Finite Element Analysis (FEA) system to help design car and truck parts that will be incorporated into future vehicles. Two of these engineers, Robert Kuhn and William Thomas, used Algor to analyze four theoretical designs of a crossmember that would sustain front shock absorber loads and serve as a front engine mounting point.

"The intent of the design project was to reduce the cost and weight of the prototype design and provide design alternatives with more efficient load carrying capability," explains Kuhn. This type of simultaneous engineering has become one of the most common methods of reducing modern automotive design and development time.

"We performed the finite element analyses for several reasons," Kuhn continues. "First, to evaluate the structural adequacy of the prototype; second, to compare the indicated stress and deflection levels of three alternative designs; and third, to insure that the proposed designs provide adequate amounts of indicated strength and stiffness."

Kuhn and Thomas analyzed the initial prototype design and three alternatives using Algor's Linear Stress Analysis Processor. With the analysis results, the engineers were able to better understand the stresses that each design underwent when a combined 5G engine load and 750 pound load was applied to each shock absorber mounting point. These loads were used in the analysis because they were estimated to be the worst case instantaneous loads that the component would be subjected to during its service life (based on data accumulated from tests on other vehicles).

Analysis results indicated that the prototype design was oversized for engine loads and inadequate for shock loads. The three alternative designs were modified to keep indicated stress levels below the material yield limit.

A line drawing of one of the four proposed cross-member designs that Chrysler engineers Robert Kuhn and William Thomas analyzed with Algor.

"Three of the four designs were created on an IBM-based Catia design system," says Kuhn. "These models were then translated to IGES and downloaded into AutoCad 10 where they were simplified, meshed, and then loaded into Algor's ViziCad Plus modeling package. The fourth model, which was chosen as the best design, was created and meshed in AutoCad 10 then transferred to ViziCad Plus. This model was designed from existing vehicle components which were downloaded from Catia to AutoCad 10 via an IGES translation.

"Once the models were in ViziCad Plus, we added FEA parameters - loads, boundary conditions, etc. - and then sent the designs through Algor's stress processor. The best model was then uploaded back to Catia (IGES translation) for incorporation into the vehicle model.

"Algor is easy to learn," Kuhn remarks. "The program is fast, and it interfaces well with other PC-based engineering and design software."