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N&V Component Structural Integration and Mounted Component Durability Implications

GM-Mark Stebbins
General Motors-Joseph Schudt
  • Technical Paper
  • 2020-01-1396
To be published on 2020-04-14 by SAE International in United States
Exterior component integration has presented competing integration challenges for suitable exterior styling, safety, N&V structural feel and component durability balanced performances. Industry standard practice of N&V vehicle mode mapping uses vehicle source, path and receiver considerations for component mode frequency placement. Mounted component mode frequency performance can have an influence on structural feel and durability performances. Component integration headwinds have increased with additional nonstructural component styling content, component size, component mass and added sensor modules. Based on first principles, the effective mass of exterior mounted components are increased due to the geometric overhang from structure. Component input vibration levels are compounded due to the cantilevered nature as well as relative positioning to the suspension and propulsion vehicle source inputs locations. Examples of vehicle end mounted components include but are not limited to headlamps, side mirrors, end gates, bumpers and fascia. Our goal is to establish basic expectations for the behavior of these systems, and ultimately to consolidate our existing rational and approaches that can be applied to such integrated systems. The focus of this paper…
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Investigations on Headlamp and Car Body Tolerances in Real Life

Audi AG-Michael Hamm, Christian Hinterwalder
  • Technical Paper
  • 2020-01-0635
To be published on 2020-04-14 by SAE International in United States
Good Lighting is cruicial for safe driving at night. Unfortunately many parameters are contributing to the final result of the individual tolerances of car body, dynamics and headlamp: The resulting aim. The paper will collect and analyse tolerance contributors from body parameters like load, tire pressure, suspension as well as aging parameters of chassis and plastic parts.
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Influence of Background Spectral Distribution on Perceptions of Discomfort Glare

Rensselaer Polytechnic Institute-Rohan M. Nagare, John D. Bullough
  • Technical Paper
  • 2020-01-0637
To be published on 2020-04-14 by SAE International in United States
The advent of light-emitting diode (LED) technology for automotive lighting allows flexibility of the spectral distribution of forward headlighting systems, while meeting current requirements for "white" illumination. As vehicle headlights have become whiter (with more short-wavelength light output) over the past several decades, their potential impacts on visual discomfort for oncoming and preceding drivers have been hotly debated. It is known that a greater proportion of short-wavelength energy increases discomfort glare, and that increasing the background light level (e.g., through roadway lighting) will decrease perceptions of discomfort. More recently it has been demonstrated that the visual system exhibits enhanced short-wavelength sensitivity for perceptions of scene brightness. As a result, roads illuminated by light sources with higher correlated color temperatures (CCTs) will be judged as appearing to be brighter than those illuminated to the same light level by sources with lower CCTs. The present laboratory study was conducted to identify whether the increased scene brightness of a road illuminated with greater short-wavelength light helps to mitigate discomfort glare more than the same scene illuminated to the…
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Influence of Intensity, Duration and Spectral Characteristics on Glare Recovery for Peripheral Visibility

Rensselaer Polytechnic Institute-Nicholas P. Skinner, John D. Bullough
  • Technical Paper
  • 2020-01-0632
To be published on 2020-04-14 by SAE International in United States
Vehicle forward lighting can use a multiplicity of light sources each varying in their spectral characteristics. Present standards for low beam headlight performance also allow variability in the peak intensities that drivers can be exposed to, as well as the durations of those exposures. Previous research has led to mixed results regarding whether the spectral distribution of a headlight source influences the length of time the visual system needs to recover the ability to see objects that might present hazards along the roadway. One recent study showed that the integrated light dose (intensity × duration) but not the spectral distribution impacted recovery times for targets presented in a constant, known location, where they would be viewed with the fovea. An experiment was carried out to assess whether the spectral distribution of a glare source might differentially impact one's ability to see a target using peripheral vision when the location of the target is not known. The findings indicate that a light source with greater short-wavelength light output resulted in longer recovery times when matched for…
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Advancements in Thermoplastic Optical Materials for Automotive Lighting Systems

Arkema Inc.-Altuglas International-Brian Cromer, Laura Thoma, Noah Macy, Charles Rissel
  • Technical Paper
  • 2020-01-0634
To be published on 2020-04-14 by SAE International in United States
Optical materials strongly influence the performance and efficiency of automotive lighting systems. In particular, LED signature headlight design motifs such as dispersion optics and light pipes comprise long optical path lengths, which require homogeneous color distribution and light extraction with minimal attenuation. Unfortunately, conventional thermoplastic optical materials are not suitable for long path length (LPL) applications, as they often lack sufficient light transmission, absorption coefficient and/or heat resistance for LPL optics. In this presentation, we will demonstrate strategies to maximize performance and efficiency of automotive lighting systems, using new acrylic resins optimized for LPL optics. Through practical examples, we will show how strategic improvements to absorption coefficient and spectral uniformity significantly reduce light attenuation, while increasing power efficiency and color uniformity in LPL optics. Additionally, we will outline thermal and physical material properties relevant to the design, engineering, and manufacturing of thermoplastic LPL optics. Finally, we will discuss the importance of outdoor stability, UV-weathering resistance, and chemical resistance for maintaining efficient long-term performance, and in the case of signature lighting, preserving the vehicle brand identity…
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Does the interaction between vehicle headlamps and roadway lighting affect visibility? A study of pedestrian and object contrast

Virginia Tech-Maury Nussbaum
Virginia Tech Transportation Institute-Rajaram Bhagavathula, Ron Gibbons
  • Technical Paper
  • 2020-01-0569
To be published on 2020-04-14 by SAE International in United States
Vehicle headlamps and roadway lighting are the major sources of illumination at night. These sources affect contrast (defined as the luminance difference of an object from its background) which drives visibility at night. However, the combined effect of vehicle headlamps and intersection lighting on object contrast has not been reported previously. In this study, the interactive effects of vehicle headlamps and overhead lighting on object contrast will be explored based on earlier work that examined drivers’ visibility under three intersection lighting designs (illuminated approach, illuminated box, and illuminated approach + box). The goals of this study were to: 1) quantify object luminance and contrast as a function of a vehicle’s headlamps and its distance to an intersection using the three lighting designs; and, 2) to assess whether contrast influences visual performance and perceived visibility in a highly dynamic intersection environment. Both luminance and contrast of roadway visibility targets and a pedestrian were measured with a calibrated photometer at a realistic intersection. Both target and pedestrian contrast and luminance were substantially affected by the intersection lighting…
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Unsteady Flow Analysis Method for Automobile LED Headlamp based on Massively Parallel CFD considering the External Environment

Hiroshima Univ-Takuji Nakashima
Kobe University-ChungGang Li, Makoto Tsubokura
  • Technical Paper
  • 2020-01-0636
To be published on 2020-04-14 by SAE International in United States
The aim of this study is to understand the mechanism of dew condensation and try to prevent it on automobile headlamp. In this case, it is necessary to accurately reproduce the complicated shape of the headlamp as the computational model. In addition, the simulation framework for predicting the turbulent flow field accompanied by the high heat source and the wall heat transfer with high accuracy in the vehicle running environment is required. Moreover, using CFD to understand the mechanism of the flow field inside the light emitting diode (LED) headlamp with a rotating fan to cool the light sources, is a challenging task because of the complicated internal structures and significant heat transfer. In this paper, we report that we tried constructing the simulation method of compressible turbulence based on hierarchical Cartesian grid using the HPC (High Performance Computing) environment. At first, we clarified the ventilation phenomenon through the vent holes in the uniform flow, and succeeded in obtaining the knowledge of ventilation control by changing the position and number of the vent holes. The…
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Automobile Headlamp: Performance and Endurance target setting approach

Mahindra Trucks and Bus LImited-Alok Kumar Mishra
Mahindra and Mahindra Limited-Nikhil gosavi
  • Technical Paper
  • 2020-01-0638
To be published on 2020-04-14 by SAE International in United States
Disproportionate number of fatal injuries happen after dark. Apart from reasons like alertness, road profile, illumination plays an important role in making night drive safe. Headlamp is the most important vehicle unit, especially during night or foggy drive. Throw, intensity and glare are some of key parameters; defining headlamp performance. Traditionally, headlamps are subjectively assessed on roads. This approach leaves lot of room for subjective understanding and corresponding improvement actions. More ever especially in commercial vehicle industry, same headlamp is used for different applications like mining or highway transportation through different mounting schemes. Therefore, a mathematical methodology was proposed to objectively assess On-road headlamp performance and endurance life.
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new

Innovative Bulb for Compact Headlamps Design

General Motors Mercosur-Israel João Cancino Junior
LUMILEDS-João Guilherme Sônego, Raphael Nunes de Souza
  • Technical Paper
  • 2019-36-0066
Published 2020-01-13 by SAE International in United States
The Single beam reflector usage with H4 halogen bulb type is adopted in low cost emerging market countries that represent a very important segment for General Motors South America region.Currently, GM engineering tech centers have developed several different solutions for H4 halogen bulb reflector type that have their package, in terms of dimensions, to meet legal requirement and performance. Taking that into consideration, this new H19LL bulb development represents a great opportunity to find out an innovative new design with reduced mass and consequently cost reduction.Besides, it could allow enhancing reflectors portfolio as well as enabling Design Studio to better define customer driven theme for the vehicle appearance.
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Daytime visibility aspects under alternative use of headlamps

ARTEB-Carlos Alberto Leite de Moura
PRIME ONE-Paulo Victor S. Pingueiro
  • Technical Paper
  • 2019-36-0072
Published 2020-01-13 by SAE International in United States
Daytime visibility represents one of the most important themes in automotive safety. Some accidents, especially frontal collisions, used to occur as a result of a bad recognition of vehicle presence. In order to keep vehicles more visible during the day, there is a luminous device called Daytime Running Lamp (DRL). Nowadays DRL is not mandatory in Brazil, but it will be in 2021 for new vehicles. As with any situation that involves technological transitions, some questions appear, among them: how to equalize the market, in terms of daytime visibility, considering newer and older vehicles together? How to improve visibility in older vehicles that were not designed with DRL? The answer maybe lies in the alternative usage of automotive headlamps. Among other facts, one luminous device for two functions can result in safety improvements without unexpected investments. Therefore, how can this technically be achieved? By CONTRAN 667, that has adopted North America references, including luminous devices according to FMVSS, it is possible to use a low beam or a high beam dimmed to a maximum 7000…
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