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Automotive styling and performance trends continue to challenge engineers to develop cost effective bumper systems that can provide efficient energy absorption and also fit within reduced package spaces. Through a combination of material properties and design, injection-molded engineering thermoplastic (ETP) energy absorption systems using polycarbonate/polybutylene terephthalate (PC/PBT) alloys have been shown to promote faster loading and superior energy absorption efficiency than conventional foam systems. This allows the ETP system to provide the required impact protection within a smaller package space. In order to make optimal use of this efficiency, the reinforcing beam and energy absorber (EA) must be considered together as an energy management system. This paper describes the development of a predictive tool created to simplify and shorten the process of engineering efficient and cost effective beam/EA energy management systems.

There are a multitude of opportunities to utilize two-shot or overmolding technology in the automotive industry. Two-shot or overmolding a thermoplastic elastomer onto a rigid substrate can produce visually appealing, high quality parts. In addition, use of this technology can offer the molder significant reductions in labor and floor space consumption as well as a reduction in system cost. Traditionally, two-shot applications were limited to olefinbased TPE's and substrates, which often restricted rigidity, structure and gloss levels. With the development of thermoplastic elastomers that bond to engineering thermoplastics, two-shot molding can now produce parts that require higher heat, higher gloss and greater structural rigidity. This paper will outline engineering thermoplastics that bond with these new elastomers, discuss potential applications, and review circumstances that offer the best opportunity to call upon the advantages of two-shot and overmolding technology.

The instrument panel (IP) is one of the largest, most complex, and visible components of the vehicle interior, and like most other major systems in passenger cars and light trucks, it has undergone considerable aesthetic and functional changes over the past decade. This is because a number of design, engineering, and manufacturing trends have been driving modifications in both the role of these systems and the materials used to construct them since the mid- '80s. This paper will trace the recent evolution of IP systems in terms of the trends affecting both design and materials usage. Specific commercial examples will be used to illustrate these changes.

Currently, automobile manufacturers receive automotive headlamp assemblies from headlamp manufacturers with outer lenses produced of clear or slightly blue tinted polycarbonate. Such headlamp designed to provide optimized light output have very similar aesthetics, and leave little room to differentiate one car platform from another, using the outer lens color. With edge glow technology a car manufacturer can provide an appealing aesthetic look (edge glow effect) from the outer lens. Additionally, this technology can be used to improve the quality of the beam color emitted through the outer lens. Dependent on the chosen combination of halogen source and lens formulation, a range of beam colors spanning from halogen to HID is attainable, where the beam pattern and color continue to conform to the applicable SAE and ECE beam photometry and color standards and regulations.

Use of thermoplastic materials for throttle body applications can offer substantial weight, cost, and integration benefits. This paper will discuss the many elements that comprise materials selection, as well as the design and testing of composite throttle bodies. Polyetherimide (PEI), polyphenylene sulfide (PPS), and polybutylene terephthalate (PBT) materials will be discussed and compared as candidates for automotive throttle bodies. The focus areas that will be covered in this paper include: Materials Selection - The criteria for materials selection will be discussed and the properties of candidate thermoplastics compared with key requirements of throttle body applications. Bore and Plate Dimensional Stability and Consistency - The effects of thermal cycling, coefficient of thermal expansion, humidity, and design will be discussed, as well as their relation to bore/plate air leakage.

The increased demands of today's complex automotive connector designs have led to the development of engineering structural analysis tools which address the performance issues of the connector's snap-finger. In designs where hand calculations were once considered the norm in evaluating snap-finger performance, the analysis tools have evolved into the use of finite element techniques which address the high nonlinearity issues of snap-finger disassembly and terminal pull out strength. The structural analysis approaches developed investigate the connector snap-finger performance in reinforced engineering thermoplastics while incorporating the effects of geometric and material nonlinearity in the results. The techniques developed allow for the evaluation of snap-finger performance of prospective connector designs before expensive tooling and prototyping is initiated, providing the benefits of limited tool rework and decreased product development time.

The gas injection molding process created a great deal of interest when it was first introduced, especially on the part of the automotive plastics industry. The process allows injection molders to make larger parts with increased rigidity at lower clamping pressures. This, in turn, allows parts to be molded that have not previously been able to be created. However, the process has been hampered by problems. First and foremost have been the numerous patent infringement suits and licensing difficulties that have retarded the spread of the technology in the United States. Second, technological problems - such as controlling the seemingly erratic nature of the gas - have also been an issue. As with any new molding technology, the plastics industry is still attempting to establish logical techniques to set up and rationalize processing conditions for the method.

Basic automotive steering wheel armature design has been largely unchanged for years. A cast aluminum or magnesium armature is typically used to provide stiffness and strength with an overmolded polyurethane giving shape and occupant protection. A prototype steering wheel armature made from a unique recyclable thermoplastic eliminates the casting while meeting the same stiffness, impact, and performance criteria needed for the automotive market. It also opens new avenues for styling differentiation and flexibility. Prototype parts, manufacturing, and testing results will be covered.

A model has been developed and implemented at GE Plastics that predicts a material's color shift when weathered. The material's color shift is due to the summation of color shifts from each individual component. By individually measuring the change in each component's optical coefficients upon weathering and using a multiple light scattering model, one can predict the color shift of a material composed of mixtures of these components. The model has been shown to have a standard deviation of 0.4 to 0.9 when predicting color shifts E*, for PC-polyester copolymers, ABS, and ABS/PC blends using an automotive exterior test, SAE J1885, ASTM D 4674, and ASTM D 4459.

With parts consolidation and increasing systems performance requirements, instrument panel systems have become increasingly complex. For these systems, the use of predictive engineering tools can often reduce development time and cost. This paper outlines the use of such tools to support the design and development of an instrument panel (IP) system. Full-scale test results (NVH, head impact, etc.) of this recently introduced IP system were compared with predicted values. Additionally, results from moldfilling analysis and manufacturing simulation are also provided.

Engineering thermoplastics are increasingly being used in automotive applications; many of whose designs are very complex and can pose unique challenges in manufacturing. To help products reach market faster, with better quality and lower cost, use of predictive engineering methods is becoming increasingly common. The purpose of this paper is to review a specific predictive tool: moldfilling analysis. This paper will outline the technology, what is required to use it properly, what issues the technology is capable of addressing, and what other tools are available for addressing advanced issues.

As a result of the increased reliance on predictive engineering to reduce vehicle development resources, increasingly accurate predictive finite element models are important to help engineers meet cost and timing restrictions. For components made of engineering thermoplastics, accurate material modeling that helps predict part performance is essential. This material modeling accuracy is even more important where high speed and high loading conditions exist such as in airbag doors, knee bolsters and pillar trim. This paper addresses material modeling of engineering thermoplastics for finite element models that are subjected to high impact and high speed loading. Here, the basics of plastics behavior are introduced and a comparison of the accuracy of different material characterizations in an impact loading is presented. The material under analysis here is a polycarbonate - acrylonitrile butadiene styrene blend, PC-ABS.

The history behind Polymer Class “A” Body Panels for automotive applications is very interesting. The driving factors behind these applications have not changed significantly over the past sixty years. Foremost among these factors is the need for corrosion and dent resistance. Beginning with Saturn in 1990, interest in polymer body panels grew and continues to grow up to the present day, with every new global application. Today, consumers and economic factors drive the industry trend towards plastic body panels. These include increased customization and fuel economy on the consumer side. Economic factors such as lower unit build quantities, reduced vehicle mass, investment cost, and tooling lead times influence material choice for industry. The highest possible performance, and fuel economy, at the lowest price have always been a goal.

Recent vehicle design trends require bumper systems to be crashworthy under more demanding circumstances, e.g. tighter package space, heavier vehicle mass, and wider rail spans. Meanwhile, pressure to reduce cost and weight of bumpers continues at a time when roles in the supplier community are changing. These factors have combined to increase the importance of optimizing bumper design and material properties for specific platforms. Materials suppliers have responded by developing a range of specialized engineering thermoplastic (ETP) resins that can help meet increasing performance requirements yet also offer the potential for improved manufacturing productivity, significant weight savings, and systems cost reductions. Material suppliers have also increased the level of technical design support provided to OEMs and 1st Tier suppliers.

To determine what effect (measured in haze), UV exposure has on polycarbonate inner lenses (coated and uncoated), when positioned behind qualifying (UV absorbent) and non-qualifying (UV transmitting) outer lens materials (clear and red). Plastic inner lenses are those covered by another material and are not exposed directly to sunlight.

The I-Section bumper design has evolved over the past 10 years into a lightweight, low cost, high performance alternative to traditional bumper beams. Initial I-Section Bumpers were developed with 40% Chopped fiberglass GMT. Through the development of lower cost Mineral-Filled/Chopped fiberglass GMT, improved static load and dynamic impact performance results have been achieved in I-Section Bumper Designs.

Current accelerated weathering protocols such as SAE J1960 or ASTM G26 do not provide reliable, predictive results for engineering thermoplastics. Correlation factors among resin types and even different colors of a single resin have variations that are 60-100% of the mean at the 95% confidence level, making these tests useless for lifetime prediction or even reliable ranking of materials. We have developed improved conditions using CIRA/sodalime-filtered xenon arc, a more rain-like water spray, and occasional sponge-wiping of the samples. The data for gloss loss and color shift agree very well with Florida data giving a correlation factor of 3100±680 kJ/m2 (at 340 nm) per Florida year at the 95% confidence level. The acceleration factor is 7.6x.

Thermoplastic body panels are emerging in the industry as automotive manufacturers seek to design for advanced aerodynamic styling, lower weight, and cost effective vehicles. To best exhibit the advantages of GE thermoplastic resins in these applications, an extensive study has been completed to demonstrate the impact performance of thermoplastic body panels in the field based on the current success with the Buick LeSabre T-Type, Buick Reatta, and the Cadillac Deville and Fleetwood models using NORYL GTX® 910 resin fenders. This study provides a “real life” scenario of the advantages of thermoplastics compared to steel in body panel applications.

The high costs of prototyping, revisions, and production tooling, with a higher emphasis on quality, concurrent with demands for miniaturization, higher-density packaging, stricter performance, and a shortened product development cycle, have led to the development of advanced analysis techniques that address the performance issues associated with failure prevention in automotive connectors. Because of the complex material and geometric nonlinearity demands in performance, traditional calculations are inadequate, and new methods, utilizing finite element analysis techniques were developed. These highly specialized analysis techniques will enable the designer and engineer to predict connector performance with a high degree of confidence. Concurrent with concept designs, structural analyses (in the areas of assembly, disassembly, and terminal retention) must be done prior to design release.

Textron Automotive Trim, Valeo Climate Control, and Torrington Research Company, with assistance from GE Plastics, have developed an integrated instrument panel system to meet ever-increasing industry targets for: Investment and piece-cost reduction; Mass/weight savings; Quality and performance improvements; Packaging and space availability; Government regulation levels; and Innovative technology. This system, developed through feedback with the DaimlerChrysler Corporation, combines the distinctive requirements of the instrument panel (IP) with the heater-ventilation-air-conditioning (HVAC) assembly. Implementing development disciplines such as benchmarking, brainstorming, and force ranking, a number of concepts were generated and evaluated. Using a current-production, small, multi-purpose vehicle environment, a mainstream concept was designed and engineered.