ALGOR SOFTWARE HELPS LEADING BRAZILIAN WHEEL MANUFACTURER REDUCE WEIGHT AND COSTS

Italmagn閟io engineers Clovis Ferreira (left) and Raymundo Gama are pictured with an Algor FEA model on the screen. The finished wheel is also shown.

The old saying that there's no need to "re-invent the wheel" is under a great deal of pressure at Italmagn閟io S.A. Ind. E. Comercio in Sao Paulo, Brazil. That's because engineers at this leading supplier of high performance wheels for automobiles, trucks and heavy equipment, are re-inventing the wheel practically every day.

Leading Supplier

Italmagn閟io has to re-invent their wheels constantly to remain a leader in a very exacting, technologically advanced industry. The company supplies original equipment wheels to most of the leading automotive companies doing business in South America. This includes General Motors, Citroen, Peugeot and others. More than eight million Italmagn閟io wheels have been sold and the company is currently increasing their production capabilities to more than 2.5 million wheels per year.

Controlling Material Costs

Italmagn閟io wheels are cast from aluminum-silicon alloys because these materials offer an outstanding weight-to-strength ratio, a good looking finish and almost total freedom to stylists. Aluminum, however, is a relatively expensive material. Expensive enough to be heavily recycled. This, combined with the fact that lighter wheels perform much better, provides Italmagn閟io engineers Clovis Ferreira and Raymundo Gama with all the reasons they need to make every effort to reduce the weight of their wheels without reducing safety.

"Automotive wheels are highly stressed components," says Mr. Ferreira. "They are classified as safety items. Their resistance to fatigue must be extensively demonstrated through physical tests, in which they are cycled to failure. Cracks must never occur within the specified test range, which represents the service life of the vehicle."

In January of 1992, Italmagn閟io began using Algor design and analysis software to develop new wheels, and reduce the need for costly, multiple laboratory tests. According to Mr. Gama, "The first project we developed with Algor software was a 5.5" x 13" wheel for the 1993 General Motors to Brazil Kadett model. The Brazilian Kadett was launched in 1988 using many of the original Opel's components. The car has received minor restyling each year since that time, with only a few items, including the wheels, being re-styled every year."

"Because of the wheel's complexity," says Mr. Ferreira, "The stress fields cannot be evaluated by simple engineering methods. The Kadett 93 wheel was specified for a 415 kgf rating. The structure had to comply with two critical mechanical requirements: first, so-called 'cornering fatigue' which is a kind of rotating bending, and second, an impact load."

A stress analysis rendering of the new wheel designed for the 1993 General Motors Opel model in Brazil. Due to Symmetry, only a section of the wheel is modeled.

The Analysis

The Italmagn閟io engineers modeled the Kadett wheel with type-5 brick elements. Because of symmetry, only one quarter of the wheel was modeled. "Von Mises linear stress analysis is a satisfactory means for checking fatigue," says Mr. Ferreira. "We used forces taken from actual laboratory testing to apply loads to the model. Boundary conditions were used to represent the forces at symmetry boundaries."

"An extremely high margin of safety was achieved after several design modifications were made on the model," continues Mr. Ferreira. "The final design performed extraordinarily well in the fatigue tests, overcoming three times the minimum life requirements of 2,320,000 cycles. We are currently working on an improved version of this wheel which will be 8% lighter than the original."

This light-shaded view of the Kadett wheel model was created for presentation purposes.

More to Come

With the Kadett wheel design under their belts, the Italmagn閟io engineers have begun work on several other new designs. In Mr. Gama's words, "One of them, the Citroen BX, had a stress concentration at the corner of the ventilation hole. The analysis allowed us to detect it in time to save unnecessary reworking. Another, the Peugeot SX-205, is going to be our lightest 5" x 13" wheel ever."

About Algor

When asked about his favorite Algor features, Mr. Ferreira has a lot to say. "First, the software's east-of-use results in a very short learning curve. Second, its unusual flexibility in providing analysis visualizations allows us to quickly detect critical stress areas. It is also easy to modify the geometry to obtain variations of the original design. We were up-and-running with Algor in less than three days and the total cost, including the hardware, changed our minds about using expensive workstations."

So, while the rest of us take hairpin turns at breakneck speeds and drive blindly through potholes without giving it a second thought, the engineers at Italmagn閟io will continue to use Algor software to "re-invent the wheel," making tomorrow's cars more efficient, safer and better looking.