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CARS speeds design functions

USING the tools provided by the Auto/Steel Partnership can reduce the weight of manufactured steel products while delivering the handling and weight carrying characteristics that customers expect from body manufacturers.

“Combining the newest generations of high strength steel and the Computerized Application and Reference System (CARS) software, body builders will be more efficient in their use of steel, providing a more competitive product for their customers,” said Samuel Errera, spokesperson for the Auto/Steel Partnership, a partnership formed by member steel and automotive related companies to perform joint research for automotive steel applications. The Auto/Steel Parnership is based in Southfield, Michigan.

Errera and co-presenter, Daniel Schiavello, explained the newest findings of the Auto/Steel Partnership during the Design Resources and Sheet Steel Applications Workshop at the 38th annual NTEA Convention and Work Truck Show in Orlando.

By bringing newer technology to the forefront of building truck bodies and trailers, greater efficiencies will be gained by manufacturers, Errera said. “Manufacturers that build everything from horse trailers to over-the-road trailers are searching for an increased payload and a diminished curb weight. We take a high strength, thinner and lighter piece of steel, and form it to obtain the same or greater results that a heavier formed billet would have provided.

“One example of CARS was its use to improve a side rail that was being designed for a light-duty truck,” Errera said. “The rail exhibited post-buckling stress that rendered one portion of the rail cross-section ineffective.

“Normally a finite element analysis would be performed. This would have cost money and time because a finite element analysis can't be accomplished overnight. The geometric analysis section of CARS solved the problem in about two hours,” said Errera. “The software helped guide the engineers to reposition a panel, and this made the side rail completely functional without increasing the gauge or weight of the material.”

The efficiency for the software is based on the calculating process used by CARS. Important logic processes are:

  1. Compute the normal stress distribution assuming all segments are as effective as possible.

  2. Calculate the effective width of each piece in question.

  3. Calculate the cross section properties of the section based on the effective portion of each piece.

  4. Compute the stress distribution using the calculated finding of the effective section.

  5. Calculate the effective width of each segment based on the revised stress distribution.

  6. Calculate the cross section properties of the section based on the effective portion of each segment.

  7. Repeat steps 4 through 6 until the area and the moment of inertia of the effective section converge to the assumed trial value. (Courtesy of Technology Century)

“We can also assist the manufacturer in choosing the correct type of steel for the application,” Errera said. “For example, within the multiple grades of steel, some are available domestically, foreign sourced, or not at all. CARS can help select alternatives to the original material choice.”

Errera discussed other forms of assistance that the Auto/Steel Partnership can provide body manufacturers. “We are working on several different levels to increase our members' knowledge base. A few examples would be the Light Truck Frame Project, Standardized Dent Resistance Test, Sheet Steel Fatigue Test, and the Standardized Corrosion Test.”

Errera said the Auto/Steel Partnership can help body manufacturers in many ways. “The best thing we can do for you is to provide information. And that's what we like to do.”

The Auto/Steel Partnership web site is

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