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Technical Paper

A Steel Solution for a Firewall Using a Hybrid Test/CAE Approach

The firewall design of a BMW1 is optimized for interior noise and weight using a Hybrid Interior Noise Synthesis (HINS) approach. This method associates a virtual firewall with a test based body model. A vibro-acoustic model of the firewall panel, including trim elements and full vehicle boundary conditions, is used for predictions in the 40 Hz - 400 Hz range. The short calculation time of this set-up allows multiple design iterations. The firewall noise is reduced by 0.9 dB and its mass by 5.1% through structural changes. Crashworthiness is maintained at its initial level using advanced steel processing. The total interior noise shows improvement in the 90 Hz - 140 Hz range.
Journal Article

Development of a New Metal Substrate for Lean NOx Trap

This paper presents a new substrate for Lean NOx Traps (LNT) which enables high NOx conversion efficiency, even after long-term aging, when using alkali metals as the NOx adsorber. When a conventional metal honeycomb is used as the LNT substrate, the chromium in the metal substrate migrates into the washcoat and reacts with the alkali metals after thermal aging. In order to help prevent this migration, we have developed a new substrate where a fine -alumina barrier is precipitated to the surface of the metal substrate. The new substrate is highly capable of preventing migration of chromium into the washcoat and greatly enhances the NOx conversion. The durability of the new substrate and emission test using a test vehicle are also examined.
Technical Paper

New Type of Metal Substrates for Catalytic Converters Durability for Elevated Temperature

As a result of higher exhaust gas temperature for an improvement of fuel consumption, catalytic converters must be much more durable at high temperature. To satisfy such requirements, we have developed an advanced metal substrate using newly developed stainless Fe-Cr-Al foil, which contains more than 7.5 mass% of aluminum. The developed foil elongates durable lifetime about 4 times compared with the conventional foils in high temperature oxidizing atmospheres. The newly developed metal substrate is suitable for exhaust systems which is used under conditions of high exhaust gas temperature above 1000 °C.
Technical Paper

Recommended Practice for Dynamic Testing for Sheet Steels - Development and Round Robin Tests

Tensile properties of sheet steels at dynamic conditions are becoming more important for automotives in recent years due to the positive strain rate effect of steels which significantly improves energy absorption capability during crash events. However, several testing techniques are used by different testing laboratories, no testing standards are available, and the quality of data generated by different laboratories is often not comparable. In order to improve the data quality at high strain rate testing conditions and thus to improve the accuracy of crash simulation results, The International Iron and Steel Institute (IISI) initiated a project to develop the “Recommendations for Dynamic Tensile Testing of Sheet Steels”. The document provides guidelines for key elements of high strain rate testing, testing techniques, input methods, specimen geometry and stress/strain measurement instrumentations.
Technical Paper

Application Development of Low Carbon Type Dual Phase 980MPa High Strength Steel

Use of high strength steel (HSS) could be an important consideration in achieving competitive weight and safety performance of the body-in-white (BIW). This study covers key technical issues in the application development. Many aspects were studied such as formability, weldability and impact strength for application of this grade to the BIW. One of the key issues is spot weldability, especially in the assembly of heavy gauge materials for structural parts. The spot weld strength appears not to satisfy the target for some HSS applications, when hardness of the nugget is high. The relation between weld strength and the chemical composition of steel sheets was studied, because hardness can be controlled by chemical composition and welding conditions. It was found that using lower carbon content or carbon equivalent compared to conventional grades could improve weld strength.
Technical Paper

Application of Ferritic Stainless Steel to Automotive Fuel System Parts

In order to meet regulatory standards for vehicle emissions, Low Emission Vehicle II (LEV-II) and Partial-Credit Zero Emission Vehicle (P-ZEV) requirements, we examined the application of stainless steel to fuel system parts, such as the fuel inlet pipe and fuel tank. We improved the formability and durability of ferritic stainless steel by improving its mechanical properties, and by applying an organic-lubricant coating and cationic electrodeposition coating, so that that fuel inlet pipe made of ferritic stainless steel SUS436L (17Cr-1Mo-Ti) with the cationic electrodeposition coating is now suitable for the mass production of cars, having high durability and low evaporative emissions.
Technical Paper

Porosity Formation in Laser Welding of Tailored Blanks

For the laser welded tailored blanks (TBs), the formability of TBs depends on pores in the weld bead. Those pores are easily formed by CO2 laser but hardly observed by YAG laser. Based on a quantitative analysis of nitrogen content in the weld metal, gases in pores and the laser induced plasma, it is considered that high temperature of the plasma encourages dissolving nitrogen into the molten metal from the root surface and the dissolved nitrogen forms porosity due to an abrupt decreasing of nitrogen solubility at solidification of the molten metal. Also, the plume temperature in YAG laser welding is lower than the plasma temperature in CO2 laser welding and the nitrogen dissolution must therefore be suppressed in YAG laser welding.