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Several different steel sheets were tested for energy absorption, using hat square columns and dynamic crash testing. Results indicate that steel sheets containing large volume fraction of retained austenite have relatively high energy absorption. The relationship between retained austenite and energy absorption was analyzed. These special steel sheets have already been successfully used for production body parts, such a front-side-member, without difficulties arising in volume production.

This paper presents a new material technology that can achieve both crashworthiness and weight reduction of the vehicle body. This new technology is based on three fundamental approaches. One is a technique for evaluating high-speed material deformation characteristics related to the crush behavior of energy-absorbing structures. A second is the material concept of high tensile steel featuring both increased material strength and higher strain-rate sensitivity in order to improve its energy-absorbing capacity. We have found 590N/mm2-class dual-phase (DP) steel consistent with this concept. The third is a technique for estimating the crush behavior of body structures, taking into account the plate thickness reduction and work hardening distribution resulting from the press-forming process. Finally, it was shown that the use of DP steel results in a 15% reduction in the weight of absorbing structures without affecting crashworthiness.

Oil type, weight and storage time effects on formability of galvannealed sheet steels were examined in punch stretching (LDH) and friction (DBS) tests. The effects of oil weights between 1 and 8 g/m2 and storage times up to three months were examined. The results suggest that application of prelube or mill oil of about 3 g/m2 is desirable to maximize formability. Lower amounts of oil could lower punch stretchability somewhat from the maximum values. On the other hand, oil weights beyond 3 g/m2 did not appear to offer additional improvements in formability. DBS friction coefficients did not change with oil weight or storage time. Storage caused some variability in punch stretching test results for samples with the mill oil. The results indicate that prelube is beneficial for the formability of galvannealed sheet steels in the specific forming modes tested here, and the benefits continue after storage for up to three months.

The influence of coatings on fatigue behavior has been examined for the following commercially produced sheet steels: uncoated titanium stabilized interstitial-free (IF); electrogalvanized titanium stabilized IF; hot-dip galvanized aluminum killed, drawing quality (AKDQ); and galvannealed AKDQ. Fully reversed bending fatigue tests were conducted at ambient temperature on Krouse-type flexural fatigue machines. A dependence of crack development was observed and correlated to the microstructure and properties of the different coatings. Furthermore, a functional design relationship for each material was determined through stress-life analysis. The experimentally determined fatigue properties were compared to conventional estimates based on tensile properties which ignore coating effects. The results of this work suggest that ductile coatings may enhance fatigue resistance, while brittle coatings may reduce fatigue life.

There are a wide range of compounds that can be used as plasticizers, but esters of phthalic anhydride and saturated linear alcohols are particularly effective for flexible PVC used in soft automotive interior parts. Compared to esters derived from branched alcohols, esters derived from linear alcohols provide some unique advantages to the flexible PVC/ polyurethane composite to meet the high standards of automotive interior trim. The LINPLAST® plasticizers have proven plasticizer performance in flexible PVC formulations. The key to their excellent performance is in the linearity in the base alcohols used. These products are the highest molecular weight phthalate esters available with the highest degree of linearity. The main performance advantages of these plasticizers are their excellent fogging properties, UV degradation resistance, permanence, and short processing dry times.

Structural Reaction Injection Molding (SRIM) is generally regarded as a thoroughly developed technology and is currently utilized in many automotive applications; most prominently door panels but also other applications, for example package trays and headliners. The traditional production process involves the placement of a glass fiber mat into a mold prior to injection of a suitable liquid resin system. Upon removal of the part, the glass mat is thoroughly encapsulated by the resin system forming a structural composite material. In the new Long Fiber Injection (LFI) process, the glass fibers are injected along with the resin mixture onto the production mold. This new process demonstrates a new approach to high productivity, low cost manufacture of LD-SRIM composites.

The principles of an electronic nose are described briefly. It is shown how a sensor array in combination with pattern recognition software can be used for quality control and classification of car interior trim materials. Anomalies such as bad smelling leather and carpet are shown as outliers. The results are consistent with GC-MS TVOC measurements as well as with data from a human sensory panel. More needs to be done, however, regarding the sensor stability in particular before the sensor array can be used for routine classification of the trim materials.

Vibration welding has been acknowledged for decades as a viable, cost-effective alternative to the use of mechanical fasteners and adhesives in a range of automotive applications. These are primarily applications in which polymer parts are joined to like polymer parts to produce a weld which is more robust than that provided by other non-welding methods, such as hot melt adhesive. This technology and the equipment which supports it has enabled carmakers and Tier I suppliers to expand the use of state-of-the-art polymers into interior and exterior components which include those requiring a high level of structural integrity.

Lear Corporation has developed a new OneStep™ Liftgate trim module. The panel consists of all mechanical components and a trim cover assembled into one module. This structural liftgate uses the trim substrate and a “beam” as the common attachment point for all liftgate hardware. The assembly includes all of the liftgate components mounted to the back of the interior trim panel.

Successful simultaneous engineering requires a team with a high degree of engineering skill and experience, knowledge of the latest materials, processes, and methodologies; and it also requires finely honed people skills. Designing the workplace for people (DFP) can facilitate collaboration, increase quality and other significant metrics, and lead to an enhanced product greatly appreciated by the customer. Design for People applies the principles of performance technology to select and retain outstanding engineers, systematically train and educate for future competency needs, and reward and motivate through traditional and non-traditional approaches. Examples of best practice enable other organizations to apply the concepts of DFP.

This paper will summarise the results of a development programme to optimise the overall performance of AA6016 aluminium type body sheet product with special emphasis on hemming and surface texture. Hemming - The main problem associated with the hemming of aluminium sheet is crack formation on the hemmed radius. This programme has resulted in improved hemming properties: a flat hem joint is now possible in 1.2 mm AA6016 with 10% pre-strain. EBT-type of surface structure - EBT (Electron Beam Texture) surface structure consists of a regular pattern of isolated pockets in contrast with the well known random structure EDT (Electron Discharge Texture) and the highly directional structure MF (Mill-Finished). Compared with EDT and MF the EBT surface structure of aluminium gives improved forming behaviour and better paint appearance.

A study of an existing B-pillar was conducted to examine the changes required to increase the lateral load carrying capability by a factor of ten. A finite element optimization package was used to adjust the geometric and material characteristics simultaneously while minimizing weight. The results show that the weight and cost necessary for the ten-fold improvement in lateral load carrying capability were very low. Further, the results illustrate how structural design optimization with finite element modeling can be effectively utilized to create cost effective elements for use in an integrated occupant protection system.

A case study of the application of shape optimization technique to the design of the third cross-member of an automotive chassis has been presented. Its fundamental frequency is only marginally higher than the maximum operating frequency of the transmission and drive shaft, which are mounted on this cross-member. The objective is to raise the cross-member frequency as high as possible so that there is no resonance and resulting fatigue damage. A sizing optimization indicated that the mass was a predominant factor. Shape optimization using approximate direct linearization method was performed and a number of design directions were obtained. The fundamental frequency of the cross-member was raised by about 4 Hz.

Minor surface defects in the clearcoat film are common place realities in modern automotive painting operations. Finessing and polishing processes are required to remove these defects and restore the clearcoat to its original condition. Evaluation of new clearcoat technologies and polishing processes has always been very subjective. This drove the development of a standardized test method for evaluating the finessability of a clearcoat. In this paper the authors will compare and contrast the differences between the traditional method used to evaluate finessability with the newly developed standardized method. The standardized method shows distinct advantages when evaluating different clearcoat technologies and polishing processes.

This paper presents two new methods to quantitatively evaluate the mechanical durability of multi-layered automotive paint systems. The first examines the resistance of the paint system to particle impacts and involves the impact of hard particles against the painted surface, under controlled conditions. The second test examines the resistance of the clearcoat layer in the paint system to surface abrasion, or mar. The test uses a steel sphere which is rotated against the paint surface in the presence of a slurry of fine abrasive particles. These two techniques have been successfully applied to a set of commercial automobile paints, and were found to discriminate well between them and give reproducible, quantitative data. The effects of the bake conditions on both the erosion and abrasion resistance of a full paint system and the abrasion resistance of a range of commercial clearcoats are examined in detail.

The formulation of injection moldable thermoplastics with small loadings of graphite nanotubes provides sufficient conductivity in molded parts to allow for use in electrostatic painting applications. Normally, plastic parts need to be painted with a conductive primer prior to the electrostatic painting of base and clear coats. The use of conductive plastics eliminates the need for the priming step, and improves paint transfer efficiency and first pass yield. These elements provide obvious savings in materials and labor. What is less obvious, however, is the dramatic positive environmental impact that can occur through the reduction in emissions of volatile organic compounds (VOCs). Graphite nanotube technology provides advantages over other technologies such as conductive carbon black. In order to reach the percolation threshold for conductivity in carbon-black-containing resins, the loading of carbon black required tends to embrittle the polymer.

Design and implementation of predictive service life performance tests also referred to as “Key Life Tests” are vital to the automotive industry to control warranty costs, track the quality of materials and processes, and in the specification of new materials systems. In addition to these roles, key life tests offer valuable insights into relating design features to performance and serving as tools to predict durability. A systems approach to assess durability of painted automotive exteriors subject to various tribological loading conditions is presented in this paper. This approach blends fundamental phenomenological understanding with real world usage “metrics” in order to implement laboratory simulations. To the authors knowledge, this is the first time, a synthesis of tribological principles and systems theory have been made for designing and implementing key life tests for paint durability. Several examples have been included to bring out the power of this approach.

The purpose of this paper is to investigate 2 issues involving the use of hollow-glass microspheres in sheet molded compound (SMC): 1) demonstrate the value of using volume fraction over weight fraction formulating to evaluate materials with significantly different densities and 2) directly compare physical property data of low density SMC to standard density commercially available SMC. The primary benefit of using hollow-glass microspheres in SMC, for the automotive industry, is reducing the weight of SMC parts.

Various toughness properties were compared between long-glass-fiber-reinforced thermoplastics and their short-fiber counterparts in an effort to understand the toughening mechanisms of the long-glass fibers in reinforced thermoplastics. It was found that long-glass fibers improve the toughness of polypropylene- based composites by rendering more resistance to fiber debonding and subsequent pull-out, especially at subambient temperatures. For nylon-based composites, which form strong fiber/matrix interfaces, long-glass fibers were found to increase the toughness by imparting more resistance to fiber breakage. Finally, fiber orientation was found to have a significant effect on the fracture toughness of reinforced thermoplastics.