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Study of the Effective Backlight Angle Influence on Vehicle Aerodynamics and Contamination

University of Campinas-Rogerio Goncalves dos Santos
General Motors LLC-Danilo Oliveira
  • Technical Paper
  • 2020-01-0691
To be published on 2020-04-14 by SAE International in United States
This paper presents contamination simulation results of a 2004 Chevrolet Malibu Maxx with different morphed rear declination angles geometry to understand that effect on the vehicle contamination. Computational fluid dynamics highly-resolved time accurate simulations were performed using a commercial Lattice-Boltzmann solver, to compare the rear end contamination with five different rear declination angles. Aerodynamics simulations were also performed and presented good correlation with theoretical data. The contamination results were compared with aerodynamics simulation results in order to find a trend between the two areas for different declination angles.
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Band gaps and torsional vibration in a periodic shaft

University of Campinas-J. R. F. Arruda
EATON Ltda.,-André L. A. M. Leão
  • Technical Paper
  • 2019-36-0224
Published 2020-01-13 by SAE International in United States
Shafts used in torque and angular velocity transmission may behave as torsional vibration amplifiers due to resonance followed by unwanted vibrations. Many technologies are applied to attenuate vibration in certain frequency ranges in automotive, aerospace and industrial applications. More recently, using the concept of periodic structures (phononic crystals and metamaterials), it has been shown to be possible to obtain frequency band gaps where elastic waves cannot propagate and, therefore, standing waves cannot build up, thus avoiding resonance. Using a few periodic cells large attenuation can be obtained, so that the structure behaves like a mechanical filter. Investigations in periodic structure dynamics have been developed in recent years aiming at to attenuating specific and wide frequency ranges. The periodic structure can be a combination of different materials, or a unique material varying the geometry periodically. This work explores the possibility of using periodic shaft structures to create torsional band gaps for torsional vibration attenuation. Theoretical models and experimental results for torsional vibrations in a periodic shaft are investigated. The approach is to build a dynamic model…
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Presentation and Comparison of Three Multiaxial Fatigue Criteria Based on Stress Invariants Applied to a Crankshaft

University of Campinas-Frederico R. Minucci, Auteliano A. dos Santos @sJr.
ThyssenKrupp Metalúrgica Campo Limpo Ltda-Rafael A. Lima e Silva
Published 2010-10-06 by SAE International in United States
The crankshaft is one of the most important components of the internal combustion engine and its function is, with the rods, transforming the linear movement of the piston into rotation. Because it is under cyclic loads during all of his life, the main type of failure in these components is due to fatigue. However, as they are subject to complex loads, multiaxial stresses are arose resulting in a problem of multiaxial fatigue. Several approaches about this problem were developed, but until now, there is no universally accepted approach. This paper presents a comparison of some multiaxial high-cycle fatigue criteria based on stress invariants, namely Sines, Crossland and Kakuna-kawada criteria. Initially, some basic concepts about such criteria are presented. To facilitate the understanding of the multiaxial fatigue approach, the paper presents also an analysis of stress and fatigue in a steel axle under bending and torsion in phase and out of phase. Next, to a crankshaft of a four-cylinder engine with a forged steel SAE 1548, a stress analysis by the method of superposition of the…
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Constant Q Transform for Automotive NVH Signal Analysis

University of Campinas-Jose Roberto de Franca Arruda
Ford Motor Co.-Belisario Nina Huallpa
Published 2010-10-06 by SAE International in United States
The constant Q transform consists of a geometrically spaced filter bank, which is close to the wavelet transform due to the feature of its increasing time resolution for high frequencies. On the other hand, it can be processed using the well-known FFT algorithm. In this sense, this tool is a middle term between Fourier and wavelet analyses, which can be used for stationary and non-stationary signals. Automotive NVH signals can be stationary (e.g., idle, cruise) or non-stationary, i.e., time-varying signals (e.g., door closing/opening, run-up, rundown). The objective of this work is to propose the use of the constant Q transform, developed originally for musical signal processing, for automotive NVH (run up, impact strip and door closing) time-frequency analyses. Also, similarities and differences of the proposed tool when compared with Fourier and wavelet analyses are addressed.
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Time - Frequency Analysis Techniques Applied to Automotive Noise and Vibration Signals

University of Campinas-Jose Roberto de França Arruda
Ford Motor Company-Belisario Nina Huallpa, Jorge Marano
Published 2008-10-07 by SAE International in United States
Automotive stationary noise and vibration signals are normally analyzed using Fourier methods. However, many noise and vibration signals are non-stationary (transient or time-varying). In those situations, the time characteristics of the signals can be lost using standard Fourier methods. Lately, time-frequency (TF) analysis methods have become more popular and are applied in many different areas of NVH (Noise, Vibration, and Harshness) in order to preserve the time-frequency information. The objective of this paper is to present some of the different time-frequency analysis tools, such as the Short Time Fourier transform (spectrogram), the Gabor Transform, the Wavelet transforms (scalograms), and the Wigner-Ville Distribution. Examples of application of these techniques to automotive non-stationary noise and vibration signals are presented.
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A CAD/CAM System Applied to Robot Programming

University of Campinas-G. N. Telles
State University of Santa Catarina-C. N. Vetorazzi @sJr.
  • Technical Paper
  • 1997-25-0541
Published 1997-06-16 by ISATA - Dusseldorf Trade Fair in United Kingdom
An automatic robot programming system was developed for PCB components insertion tasks.The system uses as input CAD files which describes the relative positions of the components on the board information about the robotics cell, and some directions about jigs and fixtures used to locate the board on the workspace, as well as correct information about component feeders. The robot program generation using this system cuts off the hard task which involves getting the data from board design and exhaustive calculations relating to the robotic workspace and jigs and fixtures. The system needs files in AutoCAD standard, and several applications were made to validate it using an IBM 7535 SCARA robot. The whole system was developed in Pascal language and the resulting programs are written in AML. It was observed that it could reduce a lot of unproductive time if manually done. It was also an algorithm to check and avoid mechanical interference in the robotic insertion tasks.