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Reduction of the Effect of the Creep Groan Brake Excitation in a Comercial Vehicle

IDIADA Automotive Technology SA-Angel Sanchez
  • Technical Paper
  • 2020-01-1530
To be published on 2020-06-03 by SAE International in United States
One of the results generated by the stick-slip intermittent motion of a brake at the friction interface is the Creep Groan Noise which is a low frequency self-excited vibration, normally less than 220 Hz. This local vibration generated between the brake couple, is transmitted through the suspension system until the passengers of the vehicle in form of vibration and noise. This paper presents a methodology that combines testing and numerical models in order to 1) detect the source of the Creep Groan, 2) create a correlated numerical model and 3) produce countermeasures that reduce the amplitude of the noise at occupant positions. The vehicle under investigation was a commercial vehicle employing air-actuated brake drums. From testing, global vehicles modes and displacements under operational conditions were respectively investigated by means of Operational Deflection Shapes and Real Time Animation. These techniques allowed to prove the existence of a feedback loop with a positive gain that excites a suspension resonance mode, creating an unstable shaking effect in the whole vehicle. In-service data suggest that the brake actuation system…
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High Speed Camera Based 3D Experimental Modal Analysis

University of Ljubljana-Domen Gorjup, Janko Slavic, Miha Boltezar
  • Technical Paper
  • 2020-01-1569
To be published on 2020-06-03 by SAE International in United States
High-speed camera systems in vibration measurements are typically limited to identifying motion perpendicular to the optical axis. Depth information, lost in the imaging process, can be recovered by using the recently introduced frequency domain triangulation and consequently full 3D deflection shapes can be obtained. This research presents the required theoretical background where the multiview image data is used for spatial small harmonic motion identification. Vibrations of an arbitrary-shaped specimen can be identified in the frequency domain using only a single, moving high-speed camera, extending the field-of-view of the established image-based vibration measurement methods. Real test cases are also presented.
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Development of the Active Sound Generation Technology using Motor Driven Power Steering System

Hyundai Motor Co.-Kyoung-Jin Chang
Mdynamix AG-Leonhard Angerpointner, Dominik Schubert, Matthias Niegl
  • Technical Paper
  • 2020-01-1536
To be published on 2020-06-03 by SAE International in United States
As original engine sound is usually not enough to satisfy the driver’s desire for the sporty and fascinating sound, active noise control (ANC) and active sound design (ASD) have been great technologies in automobiles for a long time. However, these technologies which enhance the sound of vehicle using loud speakers or electromagnetic actuators etc. lead to the increase of cost and weight due to the use of external amplifier or external actuators. This paper presents a new technology of generating a target sound by the active control of a permanent magnet synchronous motor (PMSM) which is already mounted in vehicle. Firstly, an algorithm of this technology, called an active sound generation (ASG), is introduced with those signal conversion process, and then the high frequency noise issue and its countermeasure are presented. Secondly, ASG test bench is designed using a motor driven power steering (MDPS) system and then it is checked if ASG has any influence on an original function of MDPS. Thirdly, motor-induced vibration is measured in the transfer path and then the appropriate level…
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Advance CAE Methods for NVH Development of High Speed Electric Axle

AVL LIST GmbH-Mehdi Mehrgou, Julian Pohn, Bernhard Graf, Christoph Priestner
AVL Software and Functions Gmbh-Mathias Deiml
  • Technical Paper
  • 2020-01-1501
To be published on 2020-06-03 by SAE International in United States
By developing more electric vehicles more and more focus are to the noise and vibration from Electric Drive unit. Here a high-speed E-axle for premium class vehicle is being developed up to 30,000 rpm, with high power density and lightweight design which introduce new challenges. Benchmarking of different E-axle and vehicles lead to targets which can be used at the begin of development as subsystem targets. This paper shows first how these targets like tonal noise can be simulated. Then the CAE method is used to optimize the source and structure to improve the NVH. Different aspects like torque ripple, electric whine, gears whine and mounting are discussed.
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CAE Support to Vehicle Audio Installation Issues

Volvo Car Corporation-Andrzej Pietrzyk
  • Technical Paper
  • 2020-01-1575
To be published on 2020-06-03 by SAE International in United States
Audio CAE is an emerging area of interest for a vehicle OEM, despite the fact that the development of the audio system is often left to a specialized supplier. Especially the questions regarding early stages of the vehicle design, like choosing the possible positions for speakers, deciding the installation details that can influence the visual design, and integration of the low frequency speakers with the body & closures structure, are of interest. Therefore, at VCC, the development of the CAE methodology for audio applications has been undertaken. The long term goal is to enable performing subjective evaluation of sound in a virtual car, and integrating audio evaluation in the NVH simulator. The key to all CAE applications is the loudspeaker model made available in the vibro-acoustic software used within the company. Such a model has been developed, implemented and verified in different frequency ranges and different applications. The applications can be divided into the low frequency ones (concerning the installation of woofers and subwoofers), and the middle/high frequency ones (concerning the installation of midrange and…
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The In-Depth PHEV Driveline Torsional Vibration Induced Vehicle NVH Response Study by Integrated CAE/Testing Methodology

BAIC Motor Powertrain Co Ltd-Hongzhi Yu, Shouwei lu
BAIC Motor corporation.Ltd.-Qian zhao, Li zhang, Jianning jia, LIE WU, Huimin zhuang, honghui zhao
  • Technical Paper
  • 2020-01-1507
To be published on 2020-06-03 by SAE International in United States
In this paper,an amesim 1-d refined driveline model, including detailed engine, damper, dual clutch, transmission, differential, motor, halfshaft, wheel, body, suspension, powertrain mounting and powertrain rigid body, was built up, off a p2.5 topology phev,to predict torsional vibration induced vehicle NVH response addressing differing driving scenarios,like WOT rampup,parking engine start/stop,ev driving to tipnin(engine start) then to tipout(engine stop).firstly,the torsional vibration modes were predicted,addressing differing transmission gear steps of hev/ev driving mode,and the critical modes could be detected,as such, caveats/measures could be applied to setup the modal alignment chart/warn other engineering section from the very start of vehicle development; secondly,secondly,the holistic operational testing,which defined plenty measurement points including rpm fluctuation at differing location of engine/transmission,spark angle,crank position,injection angle,valve timing,MAP/MAF,etc, partly for later model calibration,partly for extract mandatory excitation input,like cylinder pressure trace/mount and suspension force,and partly for the reference of next optimization stage, was implemented on vehicle chassis dyno in a hemi-anechoic chamber.as it was merely centered on torsional vibration induced scenarios,the intake system/exhaust system /engine radiation noise contribution was excluded by specific measures,like BAM,etc, during…
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Characterisation of Brake Creep Groan Vibrations

Graz University of Technology-Peter Fischer, Manuel Pürscher, Severin Huemer-Kals
University of Ljubljana-Jurij Prezelj
  • Technical Paper
  • 2020-01-1505
To be published on 2020-06-03 by SAE International in United States
Creep Groan is an impulsive brake noise at very low velocities of the vehicle. Generally, stick-slip between brake disc and brake pads is assumed as the most dominating vibration mechanism of creep groan. This contribution will show by sophisticated measurement techniques, that stick-slip and speed dependent friction is an important trigger of this annoying vehicle noise. However, the overall vibration is much more complex than common stick-slip vibration models. It turns out, that in typical brake systems of passenger vehicles creep groan occurs around 15-20 Hz and 70-90 Hz. The mechanism at 15-20 Hz is an impulsive noise. Transitions between stick and slip phases trigger complex nonlinear vibrations of the complete brake and suspension system. At 70-90 Hz, the vibrations show a more harmonic-like behaviour, caused primarily by speed-dependent friction characteristics. Flexibilities in the suspension bushings, elastic deformations of suspension parts, wheel and tyre support the growth of instable self excited vibrations. In practical vehicle operation, the range of 70-90 Hz is the most relevant one. In many cases, the 15-20 Hz vibrations are not…
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Noise-Vibration (NVH) Analysis & Reduction in Traction Motors-PMSMs at the Design Stage

Tata Motors, Ltd.-Vishwanatha K. Rao
  • Technical Paper
  • 2020-01-1509
To be published on 2020-06-03 by SAE International in United States
Various electric propulsion systems are used in the industrial field. Recently, research focused on permanent magnet synchronous motors (PMSMs) because of their several advantages. There are various method to reduce Noise and Vibration of traction at the Design Stage of Motor. Noise reduction has constituted a difficult study point for the last years. A great part of this acoustic noise has electromagnetic origin. The harmonic spectrum of the PWM voltage supply is very rich and every frequency has direct effects on the motor acoustics and also Various Torques effect on the Motor, In this paper, the Design Stage of Electric Motor Describe the Design Specifications and Calculations For reduce Harmonics and unwanted Torque (Electromagnetic Forces) for NVH reduction. Such as two winding methods for the interior permanent-magnet synchronous motor for vehicle traction: concentrated winding and distributed winding. Both have merits and demerits, and both influences the motor’s performance. Also the paper presents and analyses the experimental acoustic noise of AC motors controlled by drives using different PWM techniques. Five criteria are taken into account: motor…
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Design of a Multiwaves Vibration Filtering

LAUM (UMR CNRS 6613)-Adrien PELAT, François Gautier, Vicent Romero-garcia
VITESCO Technologies France SAS-Jules PLISSON, Thierry Bourdon
  • Technical Paper
  • 2020-01-1560
To be published on 2020-06-03 by SAE International in United States
In vibroacoustics, bandgap effects related to periodic and/or locally resonant architectural materials can lead to new types of structural vibration filters. This communication concerns periodic pipes used in industrial context. Such pipes are seen, as architectural structural waveguides in which bending, torsional, and longitudinal waves can propagate. To control the propagation of these vibrations and reduce their possible noise disturbance, Bragg or resonant band effects can be obtained by architecting the axial variations of the cross-section. As a result, a waveguide can be tuned to create stop bands with bandwidths large enough to make them interesting for industrial applications. For this purpose, dispersion relations are derived and analyzed based on the Floquet method and numerical Finite Element simulations. In many practical cases, all kinds of waves generally coexist due to the inevitable structural couplings. Therefore, the optimization of the geometric and mechanical characteristics of the structural couplings. Therefore, the optimization of the geometric and mechanical characteristics of the structure must be realized to attenuate several ( at least two) types of waves at the same…
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Time Domain Full Vehicle Interior Noise Calculation from Component Level Data by Machine Learning

Mercedes-Benz AG-Dimitrios Ernst Tsokaktsidis, Clemens Nau
Technical University of Munich-Steffen Marburg
  • Technical Paper
  • 2020-01-1564
To be published on 2020-06-03 by SAE International in United States
Computational models directly derived from data gained increased interest in recent years. Data-driven approaches have brought breakthroughs in different research areas such as image-, video- and audio-processing. Often denoted as Machine Learning (ML), these approaches are not widely applied in the field of vehicle Noise, Vibration and Harshness (NVH) yet. Related works mainly discuss the topic with respect to structural health monitoring, psychoacoustics, traffic noise and as improvement to existing numerical simulation methods. Vehicle interior noise is a major quality criterion for today’s automotive development. To estimate noise levels early in the development process, deterministic system descriptions are created by utilizing time-consuming measurement techniques. This paper examines whether pattern-recognizing algorithms are suitable to improve the prediction process for a steering system. Starting from operational measurements, a procedure to calculate the sound pressure level in the passenger cabin is developed and investigated. Component time domain data serves as basis for the computation. The important inputs are determined by a correlation analysis. Input selection is followed by data reduction. After preprocessing, a supervised learning environment is established.…