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SAE International Journal of Aerospace

  • Journal
  • V128-1EJ
To be published on 2019-06-28 by SAE International in United States
This is the electronic format of the journal
 

Design of Lightweight Fibrous Vibration Damping Treatments to Achieve Optimal Performance in Realistic Applications

3M-Thomas Herdtle PhD
Herrick Labs, Purdue University-Yutong Xue, J Stuart Bolton
  • Technical Paper
  • 2019-01-1524
To be published on 2019-06-05 by SAE International in United States
In recent work, it has been shown that conventional sound absorbing materials (e.g., lightweight fibrous media) can provide structural damping when placed adjacent to vibrating structures, including infinite panels, partially-constrained panels and periodically-supported panels typical of aircraft structures. Thus, a fibrous layer may serve two functions at once: absorption of airborne sound and the reduction of structure-borne vibration. It has also been found that the damping is primarily effective below the critical frequency of the structure, and that the damping results from viscous interaction between the fibrous layer and the panel’s evanescent near-field which causes there to be oscillatory, incompressible fluid motion parallel to the panel’s surface. By using a near-field damping (NFD) model based on the Biot model for acoustical porous media, it has been shown that a properly-optimized fibrous layer can provide levels of damping comparable with those provided by conventional, constrained-layer, visco-elastic, damping treatments. Based on the idea that vibrating structures exhibit a certain wavenumber/frequency response spectrum, the focus of the current study has been on evaluating the power dissipated by a…
 

Heavy-Duty Aerodynamic Testing for CO2 Certification: A Methodology Comparison

Intl. Council on Clean Transportation-J. Felipe Rodriguez, Oscar Delgado
University of Technology Graz-Martin Rexeis, Martin Röck
  • Technical Paper
  • 2019-01-0649
To be published on 2019-04-02 by SAE International in United States
Aerodynamic drag testing is a key component of the CO2 certification schemes for heavy-duty vehicles around the world. This paper presents and compares the regulatory approaches for measuring the drag coefficient of heavy-duty vehicles in Europe, which uses a constant-speed test, and in the United States and Canada, which use a coastdown test. Two European trucks and one North American truck were tested using the constant-speed and coastdown methods. When corrected to zero yaw angle, a difference of up to 12% was observed in the measured drag coefficients from the US coastdown procedure and the EU constant-speed test. The differences in the measured drag coefficient can be attributed, among others, to the assumptions in the speed-dependence of the tire rolling resistance and axle spin losses, the data post-processing required by each methodology, unaccounted frictional losses in the transmission, the behavior of the automated manual transmission during the coastdown run, and the yaw angle correction.
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Sensitivity Analysis of Tire-Soil Interaction Using Finite Element Analysis and Smoothed Particle Hydrodynamics Techniques

UOIT-Mirwais Sharifi, Moustafa El-Gindy
University of Ontario Institute of Technology-Zeinab El-Sayegh
  • Technical Paper
  • 2019-01-0174
To be published on 2019-04-02 by SAE International in United States
This paper presents the modelling, calibration and sensitivity analysis of LETE sand soil using Visual Environment’s Pam Crash. LETE sand is modelled and converted from Finite Element Analysis mesh (FEA) to Smooth-particle hydrodynamics (SPH). The sand is then calibrated using terramechanics published data by simulating a pressure sinkage test and shear box test using the SPH LETE sand particles. The material properties such as tangent modulus, yield strength and bulk modulus are configured so the simulation’s results match those of theoretical values. Sensitivity analysis of the calibrated LETE sand material is then investigated. The sensitivity analysis includes mesh size, plate geometry, smoothing length, max smoothing length, artificial viscosity and contact thickness. The effect of these parameters on the sand behavior is analyzed. Finally, SPH LETE Sand is used to determine the rolling resistance coefficient of FEA off-road truck tire size 315/80R22.5 for different mesh size sand particles. The results found within this paper will be continued in regard to achieving better understanding of vehicle dynamics for tire-terrain interaction.
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An Investigation of Aerodynamic Characteristics of Three Bluff Bodies in Close Longitudinal Proximity

Coventry University-Geoffrey Le Good, Peter Boardman, Max Resnick, Brian Clough
  • Technical Paper
  • 2019-01-0659
To be published on 2019-04-02 by SAE International in United States
The potential benefit for passenger cars when travelling in a ‘platoon’ formation results from the total aerodynamic drag reduction which may result from the interaction of bluff bodies in close-proximity. In the 1980s this was considered as an opportunity to alleviate congestion and also for fuel-saving in response to the oil crises of the 1970s. Early interest was limited by the availability of suitable systems to control vehicle spacing. However, recent developments in communication and control technologies intended for connected and autonomous driving applications has provided the potential for ‘platooning’ to be incorporated within future traffic management systems. The study described in this paper uses a systematic approach to changes in vehicle shape in order to identify the sensitivity of the benefits of platooning to vehicle style. The Windsor bluff-body model with its’ interchangeable rear-end geometry was chosen as the test subject because of its similarity to the approximate proportions of typical mid-sized European passenger cars. Three small-scale models were manufactured so as to be accommodated in-line within the working section of the Coventry University…
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Hierarchical Vehicle Active Collision Avoidance Based on Potential Field Method

Changan Intelligent Vehicle R&D Center-Gang Yi
Chongqing University-Ling Zheng, Yinong Li, Wei Yang
  • Technical Paper
  • 2019-01-1016
To be published on 2019-04-02 by SAE International in United States
In this paper, a closed loop path planning and tracking control approach of collision avoidance for autonomous vehicle is proposed. The two-level model predictive control(MPC) is proposed for the path planning and tracking. The upper-level MPC is designed based on the simple vehicle kinematic model to calculate the collision-free trajectory and the potential field method is adopted to evaluate the collision risk and generate the cost function of the optimization problem. The lower-level MPC is the trajectory-tracking controller based on the vehicle dynamics model that calculates the desired control inputs. Finally the control inputs are distributed to steering wheel angle and motor torque via optimal control vectoring algorithm. Test cases are established on the Simulink/Carsim platform to evaluate the performance of the controller. The simulation results demonstrate that the proposed control has satisfactory path tracking performance and could avoid the potential collisions effectively during the high way driving.
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An Optimization of Small Unmanned Aerial System (sUAS) Image Based Scanning Techniques for Mapping Accident Sites

Kineticorp LLC-Neal Carter, Alireza Hashemian, Nathan Mckelvey
  • Technical Paper
  • 2019-01-0427
To be published on 2019-04-02 by SAE International in United States
Small unmanned aerial systems have gained prominence in their use as tools for mapping the 3-dimensional characteristics of accident sites. Typically, the process of mapping an accident site involves taking a series of overlapping, high resolution photographs of the site, and using photogrammetric software to create a point cloud or mesh of the site. This process, known as image-based scanning, is explored and analyzed in this paper. A mock accident site was created that included a stopped vehicle, a bicycle, and a ladder. These objects represent items commonly found at accident sites. The accident site was then documented with several different unmanned aerial vehicles at differing altitudes, with differing flight patterns, and with different flight control software. The photographs taken with the unmanned aerial vehicles were then processed with photogrammetry software using different methods to scale and align the point clouds. The point cloud data produced with different vehicle / flight pattern / altitude combinations was then quantitatively compared to terrestrial LiDAR scan data. The results are presented here, as well as recommendations based on…
 

A HiL Test Bench for Monocular Vision Sensors and Its Applications in Camera-Only AEBs

CATARC-Pan Song, Rui Fang, Bolin Gao, Dongchao Wei
  • Technical Paper
  • 2019-01-0881
To be published on 2019-04-02 by SAE International in United States
This paper presents a HiL test bench specifically designed for closed-loop testing of the monocular-vision based ADAS sensors, whereby the animated pictures of the virtual scene is calibrated and projected onto a 120-degree circular screen, such that the camera sensor installed has the same vision as the observation of the real-world scene. A high-fidelity AEBs model is established and deployed in the real-time target of the HiL system, making intervention decisions based on the instance-level detection information transmitted from the physical sensor. By referring to the 2018 edition of the C-NCAP testing protocol, the HiL tests of the rear-end collision scenarios is performed to investigate the performance and characteristics of the longitudinal-motion sensing of the sensor sample under test. By comparing and analyzing the differences between the measured data and the ground truth, the sensor’s visual-perceptual capabilities with respect to accuracy and delays are evaluated in the presence of emergency braking of the subject and the leading vehicles. Finally, the matching and optimization solution is offered for performance enhancement of the camera-only AEBs using this…
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Aerodynamic Development of the 2019 Chevrolet Corvette C7 ZR1

General Motors-Alexander Nastov, David Caples
  • Technical Paper
  • 2019-01-0665
To be published on 2019-04-02 by SAE International in United States
This paper presents an overview of the aerodynamic development of the 2019 Chevrolet Corvette C7 ZR1. Extensive wind tunnel testing and computational fluid dynamics simulations were completed to engineer the ZR1’s aerodynamics to improve lift-to-drag efficiency and track capability over previous Corvette offerings. The ZR1 architecture changes posed many aerodynamic challenges including increased vehicle cooling, strict packaging demands, wider front track width, and aggressive exterior styling. Through motorsports-inspired aerodynamic development, the ZR1 was engineered to overcome these challenges through the creation of new devices such as a raised rear wing and front underwing. The resulting Standard ZR1 achieved a top speed of 212 mph making it the fastest Corvette ever [1]. Optionally, the ZR1 with the ZTK Performance Package provides the highest downforce of any Corvette, generating approximately 950 pounds at the ZTK’s top speed [1].
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The Kinematic Analysis of Occupant Excursions and Accelerations during Staged Low Speed Far-Side Lateral Vehicle-to-Vehicle Impacts

Engineering Systems Inc.-Peggy Shibata, Julius Roberts, James Sprague, Alyson Light, Jacob Stegemann, Manuel Meza-Arroyo, Shawn Capser
  • Technical Paper
  • 2019-01-1030
To be published on 2019-04-02 by SAE International in United States
The collection of research regarding occupant kinematics during low speed lateral vehicle-to-vehicle impacts is far less comprehensive than the much larger body of literature that quantifies the occupant kinematics associated with low speed rear end (longitudinal) impacts. In order to augment the available data, a series of 39 low speed far-side lateral vehicle-to-vehicle impacts were conducted in a laboratory setting. A combination of accelerometers and 3D motion tracking was used to characterize the motions of both the Target and Bullet vehicles during their collisions. The Target vehicle was initially stationary; the Bullet vehicle impacted the Target vehicle at the front passenger side door. The Bullet vehicle pre-impact speeds across all tests ranged from approximately 2.5 to 5.5 mph (4.0 to 8.9 kph; 1.1 to 2.5 m/s).Eight volunteers participated in the study. Volunteers were seated in the driver seat during the impacts and were outfitted with accelerometers on their head and wore reflective markers for 3D motion tracking on the left side of their body. The experimental design included conducting lateral impacts while the volunteers were…
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