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Technical Paper

New Materials and Experiences for the Industrialization of Pu Structural Rim Technology

1996-04-01
91A122
Processes involving use of reactive polymers received recently considerable attention also for producing components suitable for automotive structural applications. In particular polyurethane structural RIM technology seems to be the route of choice in terms of productivity, reliability and physico- mechanical performances in order to fit the automotive industry needs in the production of parts requiring superior load bearing properties. In this frame the development of long pot life snap-cure resins, fast and effective reinforcement preforming techniques as well as the development of computerized provisional processing methodologies are of paramount importance in view of industrialization of the technology. In this paper a description of the work carried out by Enichem Montedipe and Montedison is given. In particular a new family of PU systems, based on special isocyanate variants, is reported.
Technical Paper

Electrochromic Glazings for Use in Automobiles

1996-04-01
91A110
In the present paper we will outline the principles, designs, problems and benefits of electrochromic coatings and present our own laboratory results. The effect of electrochromic coatings on the thermal comfort of a parked vehicle is theoretically calculated and the results confronted with the performances of selective coatings.
Technical Paper

Multifunctional Glasses for Automotive

1996-04-01
91A109
The windows of a vehicle have to satisfy the following driver and passenger needs concerning visibility and climate perception both related to active safety: transparency, reluctance, dazzling, glare and diffused light (scattering). All functions are related to visibility and so to the optics of glazing, solar control, deicing, defogging, demisting. The task of material science is to find the multifunctional glasses solving simultaneously problems of visibility, safety and comfort. Particular kind of glasses, colored, wired, coated, electrochromic, liquid crystal, photochromic can be already considered solutions which can operate passively or actively. The example of passive solar control and active heatable coated glasses is shown as a possible practical multifunctional glass very soon.
Technical Paper

The Development of Plastic Lenses for Vehicle Headlamps

1996-04-01
91A111
The pending changes in European law enabling the use of plastic lenses on vehicle headlamps provide an opportunity for further advancement of vehicle styling, lighting performance and aerodynamic efficiency. Plastic lenses can also provide a useful weight saving and contribute to energy savings during the lifetime of the vehicle. This paper discusses the current requirements, technologies and solutions for plastic lenses, and indicates the way this advance can impact on the evolution of lighting products.
Technical Paper

Advances in Thermoset Injection Molding

1996-04-01
91A102
Injection molding of thermosetting materials such as low profile SMC/BMC composites found increasing application in the transportation industry in the eighties. Such automotive parts as front end panels and rear/hatchback doors have grown in usage. The rear doors have reached exceptional production levels of 2600/day in a single plant. The injection process offers the advantages of greater automation for the mass production of body panel parts compared in compression molding. However, the injection molding of fiber reinforced low profile composites suffers from a severe reduction in physical properties. This is particularly true for impact strength which can be one-third that of similar compression molding materials. A primary reason for this is due to the degradation of the reinforcement during the processing/molding. Efforts at increasing the physical properties through processing changes have many times caused problems with the surface smoothness of the moldings.
Technical Paper

Engineering Plastics for Novel Automotive Applications

1996-04-01
91A093
Not only have engineering thermoplastics secured an accepted place in automotive manufacture, but also their penetration of areas traditionally the sole domain of metals, is growing. One group of materials in particular is driving this trend; that of advanced thermoplastic composites. Used primarily in non-appearance, semi-structural parts, thermoplastic composites are opening the way for engineering polymers to be used in large components such as tailgates, technical fascia's or front end modules, side doors and bonnets, amongst many other novel applications whose engineering criteria could previously be met only by steel. This paper will look at both the new opportunities for engineering plastics in automotive applications and at the materials capable of economically satisfying their demands
Technical Paper

Structual Problems in the Design of a Car-Component in a Composite Material

1996-04-01
91A096
The paper summarizes the results of an experimental and numerical study performed on the rear door of a car of large production. It was carried out with a DMC ("dough molding compound") plastic material with short glass fibers. This technology makes strong the link between the production process and the mechanical properties of the component. Such properties really vary according to the fibers orientation, the distance from the injection points and the geometrical complexity of the different regions of the molded component. In some regions the fibers orientation is well defined, in others the orientation can be expressed only in average tendency terms, with a large scatter band. It is natural to think that the material modifies its behavior from region to region, showing marked orthotropic properties or, on the contrary, a compensation isotropic trend.
Technical Paper

Future Trends in Applications of Structural Composite for Automotive

1996-04-01
91A097
The paper outlines the future trends for structural applications of composite in automotive. RTM, SMC and S-RIM seem to be the most promising technologies in this field. Parts made with epoxy resins in resin transfer molding technology have very good mechanical properties that allow them to be suitable for chassis applications coupled with steel parts. The SMC compounded with Derakane resin shows very good qualities in terms of temperature resistance and a reasonable high volume of production. The last technology rising is the S- RIM that seems to be very promising because of its short cycle time coupled with mechanical properties. Several examples of applications of these different technologies are showed in the paper; some of those are already in production some others are in an advanced phase of development.
Technical Paper

Sound Quality of Impulsive Noises: An Applied Study of Automotive Door Closing Sounds

1999-05-17
1999-01-1684
This paper discusses four general attributes which quantify the character of an impulsive sound event. These attributes include the time duration, amplitude and frequency content of the impulsive noise. A three dimensional plot relating time, frequency and amplitude have been developed for the presentation of the measured data. This format allows graphic illustration of the noise event, providing fast interpretation and communication of the measured sound. Application of this methodology to the sound of an automotive door closing event is presented here. Representative door closing sound events are analyzed, with correlation presented between the attributes above to dynamic events of the physical hardware within the door and vehicle systems. Modifications of the door-in-white, internal door hardware, seal systems and additional content are investigated for their effect on the sound quality of the door closing event. Finally, recommended values for these attributes are presented.
Technical Paper

A New Wavelet Technique for Transient Sound Visualization and Application to Automotive Door Closing Events

1999-05-17
1999-01-1682
Transient automotive sounds often possess a complex internal structure resulting from one or more impacts combined with mechanical and acoustic cavity resonances. This structure can be revealed by a new technique for obtaining translation-invariant scalograms from orthogonal discrete wavelet transforms. These scalograms are particularly well suited to the visualization of complex sound transients which span a wide dynamic range in time (ms to s) and frequency (∼100Hz to ∼10kHz). As examples, scalograms and spectrograms of door latch closing events from a variety of automotive platforms are discussed and compared in light of the subjective rankings of the sounds.
Technical Paper

Door System Design for Improved Closure Sound Quality

1999-05-17
1999-01-1681
Door closing sounds are an important element of the craftsmanship image of a vehicle. This paper examines the relationship between closure sound quality and door system design. The perception of door closing sound quality is shown to be primarily related to it's loudness and sharpness. Of the two, sharpness is more important than loudness. Other factors, like ring-down may also affect closure sound quality. The door system is made up of a number of components. The most important in terms of sound quality are the door and body structure, latch, and door seals. Each of these are classified as either a sound source, a transmission path or a sound radiator. Methods for improving the design of these components for good closure sound quality are discussed in some detail.
Technical Paper

The Transformation of Recycled Painted Fascias for use in Automotive Acoustical Applications

1999-05-17
1999-01-1678
Substantial activity in the field of recycling has made industry increasingly aware of the need to find novel ways of reusing post industrial and post consumer waste to produce useful products for our markets. The traditional approaches have been to use the scrap material as is into the original markets targeted for virgin materials, and finding areas that can accept the resultant downgraded properties. This approach has created difficulties in the recycling of automotive painted thermoplastic polyolefin (TPO) fascia and trim products. The presence of the paint contaminant has substantially degraded the physical properties of the plastic. This paper reviews the use of painted TPO scrap as a raw material for automotive sound barrier applications whereby the inherent material characteristics of TPO are capitalized on. The material modifications and functional characteristics as they relate to this application are described.
Technical Paper

Design Study to Reduce the Single Engine Minimum Control Speed of the SJ30-2 Twin-Engine Business Jet

1999-04-20
1999-01-1601
A 500 pound (2.2 kN) increase in takeoff thrust per engine was predicted to increase the SJ30-2’s single engine minimum control speed (VMCA) to 109 knots (201.9 km/hr). To meet runway performance goals, VMCA had to be pushed below 97 knots (179.6 km/hr). Six types of vertical tail and rudder modifications were investigated analytically. Two vertical tail modifications and three ventral rudder configurations were tested in the wind tunnel. The tunnel showed 30° of ventral rudder deflection would reduce VMCA over 16 knots. Flight tests showed the deflected ventral rudder reduced measured VMCA speeds from 7.2 knots (13.9 km/hr) to 11.6 knots (21.5 km/hr). Other flight test techniques showed ventral rudder effectiveness to exceed that measured in the tunnel. In light of these results, a ventral rudder bias system has been incorporated into the production SJ30-2 design to assist the pilot during single engine events.
Technical Paper

Application of Shape Memory Alloys for Leading Edge Deicing

1999-04-20
1999-01-1585
Ice accumulation on aircraft wings during flight is a dangerous situation. To deal with this problem, current deicing systems either prevent ice accumulation by heating or break the ice layer once it is formed by dynamic motion of a leading edge device such as a boot. These systems may be deficient due to excessive energy requirements or ineffectiveness. In this project, the feasibility of using shape memory alloy (SMA) composite material for deicing purposes is investigated. SMA such as Nitinol wire has an unusual characteristic where it can be trained to generate a compressive strain upon application of an electric current through the wire. Several different versions of two inch radius semi-circular SMA composite specimen were manufactured and tested at Wichita State University. Ice was successfully shed in static icing tests while each of the subsequent versions reduced the power input requirement.
Technical Paper

Aerodynamic Effects of Oversized Tires and Tall Landing Gear on a Small General Aviation Aircraft

1999-04-20
1999-01-1592
An experimental investigation was conducted to identify the aerodynamic effects of oversized low-pressure (Tundra) tires and tall landing gear on a Piper Super Cub airplane. Water tunnel and wind tunnel tests were performed using, respectively, a 1/20 scale model and full-scale landing gear and tire components. Force and moment data suggest that larger tires and taller gear most affect the drag and side force. Small trim changes are apparent, but the basic static stability behavior appears unchanged.
Technical Paper

Analysis Tools for DaDTA on Riveted Lap Joints

1999-04-20
1999-01-1587
Two specific concerns that could affect safety limits for aging aircraft are the effects of corrosion damage and widespread fatigue damage (WFD) on structural integrity. A common joint in fuselage structure is the riveted lap joint, which overlaps two fuselage skin panels. This design creates complex loading conditions that require various analysis methods for accomplishing a durability and damage tolerance (DaDT) analysis. Under an Air Force research project, Boeing evaluated the capabilities of several advanced analysis tools for assessing the effects of corrosion and WFD on the structural integrity of riveted lap joints.
Technical Paper

Recommendations on Selection and Use of Cavity Reinforcement Materials

1999-05-17
1999-01-1672
Cavity reinforcement materials are used in the automotive industry to stiffen hollow cavities in unibody constructions. Typical areas of use include the engine rails, rocker panels, roof support or any other cavity in need of reinforcement. Use of these materials can allow for reductions in vehicle weight without sacrificing long-term durability and stiffness. Additional NVH benefits could be gained through the change in stiffness and through acting as a physical barrier to the propagation of noise, water and dust. The objective of this paper is to describe the properties of a new type of cavity reinforcing material and to identify key properties of reinforcing materials.
Technical Paper

Development of a New Aviation Grease

1999-04-20
1999-01-1567
Hundreds of components on the frame of an airplane are lubricated with grease. Since the performance of such components is critical, a number of grease specifications have been written to cover airframe grease applications. The proliferation of different airframe grease specifications complicates the maintenance of mixed fleets of airplanes and increases the opportunities for misapplication of grease. In the past decade, efforts have been made to reduce the number of greases required for airframe lubrication by enhancing the multipurpose nature of the relevant grease specifications. This paper compares four specifications that are used to specify airframe greases and describes a multipurpose grease which meets two of the major airframe grease specifications.
Technical Paper

An Automated System for Drill Bit Verification

1999-04-20
1999-01-1565
Aerospace manufactures purchase millions of drill bits each year for the manufacture of large aircraft structures. This paper describes an ongoing research project for the development of an automated system to detect poor quality drill bits before they are put to use.
Technical Paper

Fatigue Analysis of an Aircraft Wing Spar

1999-04-20
1999-01-1561
During full body fatigue testing, an aircraft wing spar initiated a crack from a rivet hole and crack growth data was obtained unique to the test spectrum loading. Fatigue testing of the 7050-T73511 spar material was used to obtain crack growth rate data and variable amplitude fatigue crack growth tests were performed on specimens fabricated from the spar material. Calculated results were in excellent agreement with these experimental results. A layered analysis of the adhesively bonded spar showed that the stress intensity in the lower cap was approximately constant, independent of crack length. When the constant stress intensity is used in a variable amplitude fatigue crack growth analysis, there is good correlation between the predicted and observed crack growth rates.
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