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Automotive fenders is one such example where specialized thermoplastic material Noryl GTX* (blend of Polyphenyleneoxide (PPO) + Polyamide (PA)) has successfully replaced metal by meeting functional requirements. The evolution of a fender design to fulfill these requirements is often obtained through a combination of unique material properties and predictive engineering backed design process that accounts for fender behavior during the various phases of its lifecycle. This paper gives an overview of the collaborative design process between Mitsubishi Motors Corporation and SABIC Innovative Plastics and the role of predictive engineering in the evolution of a thermoplastic fender design of Mitsubishi Motors Corporation's compact SUV RVR fender launched recently. While significant predictive work was done on manufacturing and use stage design aspects, the focus of this paper is the design work related to identifying support configuration during the paint bake cycle.

This paper investigates the potential of using FEA poro-elastic Biot elements for the modeling carpet-like trim systems in a simplified setup. A comparison between FEA computations and experiments is presented for two layer (mass-spring) trim systems placed on a test-rig consisting in a 510×354×1.6 mm flat steel plate clamped in a stiff frame excited at its base. Results are presented for a given heavy layer with two different poro-elastic materials: one foam and one fibrous material. The investigations included accelerometer measurements on the steel plate, laser-doppler vibrometer scans of the heavy layer surface, sound pressure measurements in free field at a distance of 1 meter above the plate, as well as sound pressure in a closed rectangular concrete-walled cavity (0.5×0.6×0.7 m) put on top of the test-rig. Computations were carried out using a commercial FEA software implementing the Biot theory for poro-elastic media.

A new single-brick Ba + alkali metals NOx-Trap catalyst has been developed to replace a two-brick NOx-Trap system containing a downstream three-way catalyst. Major development efforts include: 1) platinum group metals selection for higher HC oxidation with potassium-containing washcoat, 2) alumina and ceria selection, and Rh architecture design for more efficient NOx reduction and 3) NiO to suppress H2S odor. Mitsubishi Motors' 1.8L GDI™ with this Delphi new NOx-Trap catalyst with H2S control achieves J-LEV standard with less cost and lower backpressure compared to the previous model. It is further discovered that incorporation of NiO into the NOx-Trap washcoat is effective for H2S control during sulfur purge but has a negative impact on thermal durability and sulfur resistance. Further study to improve this trade-off has been made and preliminary results of an advanced washcoat design are presented in this paper. Details will be reported in a future publication.

A method of fatigue life prediction of spot welded joint under multi-axial loads has been developed by fatigue life estimation working groups in the committee on fatigue strength and structural reliability of JSAE. This method is based on the concept of nominal structural stress ( σ ns) proposed by Radaj and Rupp, and improved so that D value is not involved in stress calculation. The result of fatigue life estimation of actual vehicle with nominal structural stress which was calculated through newly developed method had very good correlation with the result of multi-axial loads fatigue test carried out with test piece including high strength steel.

Galvannealed steel sheet (GA) is very extensively used for vehicle panels. However ζ-phase (FeZn13) in GA coat causes poor stamping formability. Previously, there were no easy methods to evaluate the influence of ζ-phase on the frictional characteristics other than the X-ray diffraction method. This study will discuss the development of a new testing method: Dr. STAMP Method that is both efficient and convenient with pin-on-disc tester.

Tensile testing technique for the small sample was newly developed. Small tensile specimens with gage length of 1mm were taken from spot welds of high tensile strength steel sheets, and stress-strain relationships and ductility of base metal, heat affected zone including corona bond and nugget were individually measured. Finite element analyses of spot-welded joints under the conditions of static and dynamic tensile-shear loading were carried out with these local mechanical properties to predict the fracture mode and strength of the joints. It was clarified that the effects of both nugget diameter and class of steels were evaluated with good accuracy.

The International Lubricant Standardization and Approval Committee (ILSAC) ATF subcommittee members have compared the two oxidation bench test methods, Aluminum Beaker Oxidation Test (ABOT) and Indiana Stirring Oxidation Stability Test (ISOT), using a number of factory-fill and service-fill ATFs obtained in Japan and in the US. In many cases, the ATFs were more severely oxidized after the ABOT procedure than after the same duration of the ISOT procedure. The relative severity of these two tests was influenced by the composition of the ATFs. The bench test oxidation data were compared with the transmission and the vehicle oxidation test data.

This paper describes the lap welding of Zinc-coated steel sheet using a high power continuous wave YAG laser. The well-known problem of welding the Zinc-coated sheet is related to the low boiling point of zinc compared with the melting point of steel. During lap welding, zinc coating at the interface vaporize rapidly and causes defects1)2). In this study, therefore, lap welding was performed by YAG laser. The effects of type of coating layer, welding conditions, tensile strength and corrosion resistance after electro-deposition was examined. It was found that the weldability of coated steel is different by type of coating. Zn-Ni coated steel showed good weldability, but galvanealed steel inevitably pore pits with no gap set up. These defects not only lower the strength of joint, but also produce irregular bead where easily corroded after electro-deposition.

Gas shielded metal arc welding is generally applied to automobile chassis parts. However, the weld parts with the E-coat show poor corrosion resistance. Therefore, the corrosion mechanism of the weld parts was investigated. The results found two reasons why the weld parts corroded faster than the non weld parts:(1)inadequate phosphating (2)defects in the E-coat. After detailed investigation, it was clarified that the major cause of poor corrosion resistance was the defects in the E-coat caused by slags formed on the surface of the weld bead. Therefore the amount of slag has to be decreased to improve the corrosion resistance. The effect of shielding gas composition on the amount of slag was then investigated. In the case of Ar and oxidizing gas mixture, the corrosion resistance improved as the oxidizing gas content decreased. This was due to the reduction of slags.

In order to investigate the corrosion resistance of organic composite-coated steel sheets ( OCS ) in a real automotive environment, many kinds of corrosion tests were performed on test pieces and real automotive doors. Tests with a corrosive solution including iron rust were introduced to simulate the real corrosive environment of automotive doors. The relationship between the components of OCS and the corrosion resistance in the rust-including tests was examined. In addition, electrochemical studies were performed. Results indicate OCS has much better corrosion resistance than plated steel sheets with heavier coating weight in all tests. OCS shows excellent corrosion resistance in rust-free corrosive solution, however, some types of OCS do have corrosion concerns in rust-including tests. It became clear that these OCS types have an organic coating with lower cross-linking.

A wider usage of hot rolled high strength steels (HRHSSs) are intensively studied for more complicated underbody structural parts of cars now. With an emphasis placed on the improvement of sheared-edge flangeability, we have developed new types of HRHSSs ranging from 440N/mm2 to 690N/mm2 in ultimate tensile strength (UTS). The microstructure and chemistry of these steels were controlled: The hard second phase in the polygonal ferrite matrix was controlled both by adjusting the chemical composition, mainly, silicon-content, and by applying thermomechanical treatment to a hot strip mill. Compared to conventional high strength steels such as a high-carbon, low-silicon steel and a niobium-bearing steel, various formability-performances of the developed steels were found to be good.

Recently, many kinds of coated steel sheets are developed and used for automobile panels. Some of them show higher coefficient of friction and poorer formability than a cold rolled steel sheet. New polymer lubricating films are developed and proved to improve frictional characteristics of coated steel sheets in this study. The developed polymer lubricating films are applied to Electro Galvanized steel sheet and Hot Dip Galvannealed steel sheet, and coefficient of friction and formability of them are measured by using model dies. Different coefficients of friction are obtained by a change in a combination of components in a polymer lubricating film. As a result, the most suitable coefficient of friction is able to chose in forming conditions by the developed polymer lubricating films.

For the automotive exposed panels, several types of 350N/mm2 grade bake-hardenable sheet steel have been developed and actually applied. However for further weight reduction of automotive body panels, especially inner panels, a 450N/mm2 grade sheet steel with excellent formability has been required. For this demand a new 450N/mm2 grade sheet steel has been developed. As the result it was found, that by the co-addition of Mn and P to ultra-low carbon interstitial free steel the recrystallization texture favorable for deep drawability can be formed, accompanied with the increase in tensile strength, when hot band coiled temperature is lower than 773K. In order to improve the property of the 450N/mm2 grade steel, the effect of Si content has been studied. It was found that the deep drawability is not deteriorated by the addition of Si into the Mn and P co-added ultra-low carbon IF-steel.

Two types of TS 450 to 600 MPa grade hot rolled high strength steels have been developed whose strength increases by a post-deformation heat treatment. One is a nitrogen added steel, produced by a low temperature coiling method. This steel shows an increase in tensile strength by about 60 to 90 MPa after a conventional baking treatment. The other is a Cu-bearing steel, produced also by a low temperature coiling method. This steel shows much larger increase in tensile strength by about 200 MPa due to the precipitation hardening of copper, but it requires an additional heat treatment at a relatively high temperature such as 600° C.

Vibration damping steel sheets (VDSS), which have sandwich structures with intermediate layers of resin, have been studied. The most important characteristics of VDSS for inner panels of automotive vehicles are the vibration damping properties, press formability and spot weldability. Vibration damping properties, which are quantified by loss factor,η, were influenced by both tanδ, which indicates damping capacity of resins, and elastic modulus of core resin. From a view point of vibration damping properties, resins with larger tanδ and relatively lower elastic modulus were favorable. Because these mechanical characteristics vary considerably with temperature, it is important to select the most suitable resin for the service temperature range. The relationship between noise reduction effect and loss factor of VDSS were also studied. It was experimentally confirmed that noise reduction effect of VDSS is proportional to the logarithm of their loss factor.

The objective of this paper is to present one of the application of the finite element method (FEM) in early stages of vehicle development to calculate larger deflections of body sheet panel. The stiffness of sheet metal shells is defined in conjunction with the local elastic buckling instability under concentrated loads. Considerable amount of weight reduction of outer panels could be obtained by optimizing metal gauges, radii, peripheral conditions and reinforcing manner of the panel. Among several outer panels of an automobile, a roof panel is picked up as an example and its stiffness is calculated by FEM analysis. The results shows satisfactory coincidence with the experimental ones. Regarding the calculation procedure, Central Processor Unit (CPU) time of finite elements was found to be reduced by varying and optimizing supporting conditions of the panel. Furthermore, the stiffness analysis program during the initial design stages of vehicle development is described.

In order to help the gauge reduction of wheels and chassis parts of automobiles, a form-able and weldable hot rolled steel of 550 MPa grade, named FDP-55, has been developed. FDP-55 is an 0.14% C, 0.1% Si, 1.1% Mn and Nb free A1-killed steel obtained by controlled-cooling to a low coiling temperature on a runout table, and it is featured by ferrite-degenerated pearlite microstructure. Results of co-operative works with automotive makers showed that FDP-55 was successful in the application to wheels and chassis parts attaining the large weight reduction. This paper reports the metallurgical features and characteristics of the steel.

In order to attain the gauge reduction of outer body panels without spoiling the dent-resistance and formability, a bake-hardenable Al-killed steel sheet, named RBH-35, and has been developed in the conventional box-annealing process. RBH-35 is an 0.01% carbon, low manganese and rephosphorized Al-killed steel sheet retaining solute carbon of about 10 ppm. The steel exhibits high r-value, bake-hardenability of 40 MPa, ultimate tensile strength of above 350 MPa and substantially non-aging property. Results of stamping test of door outer panel showed that RBH-35 is the most suitable steel sheet for the thinning of outer body panels by about 10%. This paper reports the metallurgical features, mechanical properties and applications of the steel.

Recently, it has become more important to improve the corrosion resistance of automotive body panels, and the amount of coated steel sheets has been increasing for this application. Several types of coated steel sheet, such as Zincrometal, hot-dip galvanized steel sheets, galvannealed steel sheets and electrogalvanized steel sheets are widely available. Sumitomo Metal Industries have studied new coated steel sheets for automotive body panels, and have succeeded in the development of the new NiZn alloy plated product “SZ”, the deposit of which includes about 13% nickel. This paper discusses the plating conditions, production process, properties and performance of SZ.

In search for thinner auto-body panels, investigation has been made on the level of yield strength of high strength steel sheets in view of the fact that the dent resistance must be at least equal to that of today's mild steel panels. Dent resistance should be evaluated for slight dent, and loss of the dent resistance caused by thinning is most remarkably seen in this case. Rephosphorized aluminum killed steel with bake-hardenability is most favourable, taking the necessary resistance to slight dent and the formability into consideration.