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Technical Paper

Nylon RIM Development for Automotive Body Panels

1985-02-01
850157
The performance and production requirements for future passenger vehicles has increased the efforts to replace metal body panels with plastic materials. This has been accomplished, to a large extent on some production vehicles that have been introduced recently. Unfortunately, these plastic body applications have necessitated special off-line handling or low temperature paint processing. However, the advantages of RIM nylon, offer the potential for uniquely new plastic body designs, that can be processed through existing assembly plants, much like the steel panels they are intended to replace. The intent of this paper is to discuss the rationale for future plastic body panel material selection and related nylon RIM development efforts.
Technical Paper

Field Evaluation of Down-Gauged High Performance RIM Fascia Polymers

1993-03-01
930539
Reducing the wall thickness of automotive fascia offers cost and weight savings over those manufactured today. New high performance RIM polyurethane/urea and polyurea polymers with improved mechanical properties over conventional systems make down-gauging possible while maintaining specified performance.1 Adding low cost, high surface quality fillers to these polymers provides enhanced dimensional stability in fascia at reduced wall thickness, thus meeting ever increasing demands for lower cost and high quality. This paper describes validation studies of filled RIM fascia down-gauged 22% to 3.0 mm wall thickness and compares them to conventional fascia moulded at nominal 3.9 mm wall thickness. High performance polyurethane/urea, polyurea, and conventional polyurethane/urea each incorporating wollastonite, mica, or milled glass were tested. The data include “on-car position” moisture stability, painted impact at low temperature, and material processing.
Technical Paper

Analytical and Experimental Techniques in Solving the Plastic Intake Manifold NVH

2001-04-30
2001-01-1544
The intent of this paper is to summarize the work of the V8 power plant intake manifold radiated noise study. In a particular V8 engine application, customer satisfaction feedback provided observations of existing unpleasant noise at the driver's ear. A comprehensive analysis of customer data indicated that a range from 500 to 800 Hz suggests a potential improvement in noise reduction at the driver's ear. In this study the noise source was determined using various accelerometers located throughout the valley of the engine and intake manifold. The overall surface velocity of the engine valley was ranked with respect to the overall surface velocity of the intake manifold. An intensity mapping technique was also used to determine the major component noise contribution. In order to validate the experimental findings, a series of analysis was also conducted. The analysis model included not only the plastic intake manifold, but also the whole powertrain.
Technical Paper

All Thermoplastic Lightweight Structural Rear-Seat-Back

2001-03-05
2001-01-0324
An innovative seat back design for fold down split-rear seat backs has been developed for application in SUV’s, MPV’s and hatchbacks. The all-thermoplastic seat back design meets US and European government regulations such as, the FMVSS 210, 207 in the US, and ECE 17 (luggage retention) in Europe. It is also expected to meet the newly introduced FMVSS 225 (child seat belt tether load) requirement. Currently application of the blow molded seat back is limited to sedans where the seat belt anchor loads are transmitted to a steel package shelf. For applications where the seat-belt anchor loads are transmitted to the seat back, hefty steel frame and reinforcements are required which add weight and cost to the seat back. The same is true for seats that need to comply with the European luggage retention requirement.
Technical Paper

Use of CAE Methods for Optimization of Polypropylene Structural Components in Automotive Applications

2000-12-01
2000-01-3163
Since their introduction in automobiles, polymeric materials have enabled designers and engineers to differentiate products based on performance attributes, mechanical response, aesthetics, and manufacturing techniques. A large segment of these applications utilizes polypropylene (PP) resins. One of the attractive features of PP polymers is the ability to tailor their mechanical, thermal and processing performance envelope via modification of their composition and the addition of fillers. Key to the successful application of PP resins in structural systems is the ability of designers and engineers to understand the material response and to properly model the behavior of PP structures upon different mechanical and thermal loading conditions.
Technical Paper

Impact of Plastics on Automotive Applications and Their Role in Enabling Technology Innovation

2000-12-01
2000-01-3164
Automotive manufacturers are driving for improvement, creativity and innovation in vehicle systems in order to differentiate products in the global market. Progress in fuel efficiency, occupant safety, comfort, recyclable friendly pre-assembled modular systems, and novel manufacturing methods is difficult to achieve if no major departure from the traditional design, engineering, material mix, and assembly approaches is considered. More importantly, these benefits will not materialize unless the relationship between automotive manufacturers and suppliers changes, allowing suppliers to take a more active role in the vehicle development process. The present paper explores achievements made towards the development of new, innovative technologies to address simplification and overall performance improvements using non-traditional materials.
Technical Paper

A Bursting Failure Criterion for Tube Hydroforming

2002-03-04
2002-01-0794
Fundamental differences exist between sheet metal forming and hydroforming processes. Sheet metal forming is basically a one step metal fabrication process. Almost all plastic deformation of an originally flat blank is introduced when the punch is moved normal to a clamped sheet metal. Hydroforming, however, consists of multiple steps of tube making, pre-bending, crushing, pressurization, etc. Each of the above mentioned steps can introduce permanent plastic deformations. The forming limit diagram obtained for sheet metal forming may or may not be used in hydroforming evaluations. A failure criterion is proposed for predicting bursting failures in tube hydroforming. The tube material's stress-strain curve, obtainable from uniaxial tensile test and subjected to some postulations under large stress/strain states, is used in judging the failure.
Technical Paper

Advancements in RRIM Fascia Application Provide Cost Competitiveness While Meeting Performance Requirements

1997-02-24
970482
The commercial validation of a optimized RRIM polyurethane substrate with a novel barrier coat for fascia applications is reviewed which creates cost competitiveness to thermoplastic olefins (TPO), without sacrificing performance. Meeting fascia performance requirements with thinner and lighter RRIM materials containing recyclate and the subsequent application of a barrier coat eliminating the traditional primecoat cycle was investigated.
Technical Paper

LS-DYNA3D Finite Element Model of Side Impact Dummy SID

1997-04-08
971525
Side impact dummy (SID) is a human-like test device used in the National Highway Transportation Safety Administration (NHTSA) mandated side impact test of vehicles sold in the USA. A finite element model of SID has been developed at GM as a part of a project to simulate the side impact test. The objective is to better predict physical test results by replacing traditional rigid-body lumped parameter models with a finite element model. The project included, besides mesh generation, the development of new LS-DYNA3D constitutive models for rubber and foam-like materials, and enhancements of contact interface and other algorithms. This paper describes the GM SID finite element model and its performance in side impact test simulations.
Technical Paper

High Performance Damping by a New Generation of Spray-On Coatings

2003-05-05
2003-01-1581
Car manufacturers continue to strive to find creative routes to differentiate their vehicles while continuing to reduce cost. Acoustic comfort derived from high performance sprayable dampener systems is one important option for OEM's to differentiate their models. But there is a significant conflict between high performance, low cost and vehicle weight reduction. This paper describes an innovative vibration dampening material resin. It is a one part, reactive, solvent free, sprayable, epoxy based technology using a unique polymer resin with reduced safety labeling requirements. Good corrosion protection and oil absorption characteristics allow this resin to be applied in either the body or paint shop facilities. Benchmarking against the existing dampener type in the areas of damping performance, process costs, ease of application and environment/health aspects shows that this new generation of epoxy damper is superior to other current damper coatings.
Technical Paper

New Modified Dow Polyamide Resins Solving Under-the-Hood Warpage Problems

2002-07-09
2002-01-2104
Polyamide resins are well established within the automotive industry and are widely used in a range of demanding under-the-hood applications such as valve covers and air intake manifolds. In reality however, the disadvantages of conventional nylon products, such as excessive warpage and poor dimensional stability to name but two, make it increasingly difficult for engineers to produce the ever more complex parts demanded by new engine developments. In this paper we shall introduce a new range of modified Dow Polyamide resins that greatly reduce the above mentioned disadvantages. In comparisons with commercially available nylon 6 and 66 materials we shall illustrate improved warpage behaviour and lower moisture pick-up in combination with excellent chemical resistance to, for example, hot motor oil and ethylene glycol. In summation, examples will be provided to illustrate the improved utility of these new, modified Dow Polyamide resins.
Technical Paper

Application of a Constrained Layer Damping Treatment to a Cast Aluminum V6 Engine Front Cover

2005-05-16
2005-01-2286
Constrained Layer Damping (CLD) treatments have long provided a means to effectively impart damping to a structure [1, 2 and 3]. Traditionally, CLD treatments are constructed of a very thin polymer layer constrained by a thicker metal layer. Because the adhesion of a thin polymer layer is very sensitive to surface finish, surfaces that a CLD treatment can be effectively applied to have historically been limited to those that are very flat and smooth. New developments in material technology have provided thicker materials that are very effective and less expensive to apply when used as the damping layer in a CLD treatment. This paper documents the effectiveness of such a treatment on a cast aluminum front cover for a V6 engine. Physical construction of the treatment, material properties and design criteria will be discussed. Candidate applications, the assembly process, methods for secondary mechanical fastening will be presented.
Technical Paper

An Economic and Environmental Life Cycle Evaluation of 100% Regrind ABS for Automotive Parts

1998-11-30
982196
The use of regrind acrylonitrile-butadiene-styrene (ABS) for automotive parts and components results in two types of financial savings. The first is the shared monetary savings between General Motors and the molder for the difference in the virgin resin price versus price of the ABS regrind. The second is a societal energy savings seen in the life cycle of virgin ABS versus reground ABS. An added benefit is the preservation of natural resources used to produce virgin ABS.
Technical Paper

Viscosity Effects on Engine Wear Under High-Temperature, High-Speed Conditions

1978-02-01
780982
Four multigrade engine oils, containing the same base oil plus SE additive package but VI improvers of differing shear stability, were evaluated in 80 000 km of high-speed, high-temperature vehicle service. Bearing, piston ring and valve guide wear, as well as oil consumption, oil filter plugging and engine cleanliness were all worse for the engines operated on the low-shear stability oils. The wear differences were traced to differences in high-shear-rate viscosity, while the cleanliness, filter plugging and oil consumption differences occurred because of excessive wear or polymer shear degradation. These results suggest that engine oil viscosity should be specified under high-shear-rate conditions.
Technical Paper

A Connectorized Passive Optical Star for Automotive Networking Applications

1994-03-01
940798
This paper introduces for the first time a fully connectorized passive optical star for use with plastic optical fiber that addresses all automotive application requirements. A unique mixing element is presented that offers linear expandability, uniformity of insertion loss, and packaging flexibility. The star is constructed of all plastic molded components to make it low cost and produceable in high volume and is single-ended to facilitate vehicle integration. The star is connectorized to facilitate assembly into the vehicle power and signal distribution system.
Technical Paper

Structural Front-End Carrier Using Long Glass Fiber Polypropylene

2002-11-19
2002-01-3563
Modular front-end carriers to pre-assemble front-end components such as cooling systems, lights, and bumper beam have been in production in different vehicles for several years. Compression molded or overmolded steel/plastic carriers have traditionally been used. The present paper explains the design, material options, and engineering optimization of a composite front-end carrier, which utilizes long glass fiber injection moldable resins and adhesively bonded steel reinforcements. Experimental evaluation of prototypes shows the system met the functional performance requirements at minimum weight.
Technical Paper

Evolution of Structural Instrument Panels

2002-03-04
2002-01-1270
In structural Instrument Panels the conventionally used cross car beam is eliminated by using the plastic structure as a load carrying construction. Due to the continuous search for lowering costs and weight in the development of new cars, the concept has been applied a number of times. Many articles have been published since on this subject, describing the design concepts, engineering development and types of plastic material applied. In general, the structural instrument panel assemblies show to have substantially lower cost and weight compared with conventional cross car beam based instrument panel structures while all of performance requirements are met. Also, improved packaging space, reduction in assembly time and improved recyclability are seen as major advantages. The use of state of the art Computer-Aided Engineering (CAE) has proved to reduce development time and costs.
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