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Products and solutions, 2003-09-09, 02:00 AM

Higher crash energy absorption, lower weight: side members made from Thyssen Tailored Tubes®

ThyssenKrupp Stahl AG is unveiling its new tapered Thyssen Tailored Tubes® at the 2003 Frankfurt International Motor Show. The laser-welded and hydroformed tubes have been developed for the production of components such as side members and give automakers the opportunity to further improve the crash performance of their vehicles while reducing weight.

Automotive side members are a key passive safety component, particularly in the event of a head-on collision. Their job is to absorb as much of the collision energy as possible through defined uniform deformation under high load. The conventional method of producing side members is to weld together deep-drawn sheet metal shells. Under its NewSteelBody project (NSB®), ThyssenKrupp Stahl designed side members from tapered Thyssen Tailored Tubes® and compared their structural performance with authentic data from the reference vehicle (Opel Zafira). The findings showed that the specific energy absorption of the new design - i.e. the ratio of energy absorbed to the mass of the component - outperformed the reference model by a factor of 1.6.

This is because the tapered Thyssen Tailored Tubes® combine a number of advantages. The laser-welded tubes dispense with the weld flanges required on classic shell components. Moreover, the hydroforming process allows them to be shaped to make optimal use of available packaging space. Their tapered, thin-walled design makes full use of the strength (and thus weight) advantages offered by advanced high-performance steels. The cross section of the side member increases from front to rear, providing more and more material as deformation progresses so as to allow targeted and uniform deformation.

The NSB® side members are made from a multiphase steel with a tensile strength of 700 megapascals. Trapezoidal blanks are used as semis to produce the tapered Thyssen Tailored Tubes®. The NSB® side members have a diameter tapering from 115 to 74.5 millimeters and a wall thickness of 1.4 millimeters. To manufacture tubes of such high diameter and comparatively low wall thickness, ThyssenKrupp Stahl AG has developed its own production technology. The process is designed to retain most of the steel`s forming potential for energy absorption, rather than sacrificing it to work hardening during tube forming. Prototypes for the side members were manufactured using pre-production dies by ThyssenKrupp Drauz GmbH, a company from the Automotive segment of the ThyssenKrupp Group and a leader in hydroforming, tool/diemaking and prototyping.

Contct:
ThyssenKrupp Steel AG
Dietmar Stamm
Tel.: +49 203 / 52 - 2 62 67
Fax: +49 203 / 52 - 2 57 07
e-mail: dietmar.stamm@tks.thyssenkrupp.com

Bernd Overmaat
Tel.: +49 203 / 52 - 4 51 85
Fax: +49 203 / 52 - 2 57 07
e-mail: bernd.overmaat@tks.thyssenkrupp.com

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