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Powertrain NVH, 2017

2017-03-28
The papers in this collection reflect the recent advances on the research, development and practices of Powertrain NVH treatment. The technical papers are of interest to powertrain system designers, testing specialists, NVH experts, and other individuals who evaluate and develop technologies to control powertrain NVH. The coverage includes: engine, engine subsystem and components noise and vibration; powertrain systems noise measurement and instrumentation; powertrain systems noise analysis.
Video

Spotlight on Design Insight: Sensors: Noise Avoidance and Cable Manufacturing

2015-05-07
“Spotlight on Design: Insight” features an in-depth look at the latest technology breakthroughs impacting mobility. Viewers are virtually taken to labs and research centers to learn how design engineers are enhancing product performance/reliability, reducing cost, improving quality, safety or environmental impact, and achieving regulatory compliance. Extreme environment sensors require extreme environment cables that can reliably perform in temperatures up to 2300° F, withstand intense vibration, and have extraordinary strength. In the episode “Sensors: Noise Avoidance and Cable Manufacturing” (8:53), an engineer at Meggitt Sensing Systems demonstrates the intricate process of developing cable for sensors used in these situations.
Technical Paper

Tire NVH Optimization for Future Mobility

2020-09-30
2020-01-1520
Vehicle NVH (Noise, Vibration and Harshness) is one of the most critical customer touchpoints which may lead to buying decisions. The importance of Noise inside the cabin is increasing day by day because of the new era of E-mobility and autonomous driving. Noise source could be the engine, powertrain, tyre, suspension components, brake system, etc. depending on driving conditions. Among these, tire noise is being identified as biggest contributor at constant mid-speed driving where engine and powertrain operate at minimum noise and wind noise is also at a moderate level. This driving condition becomes very significant for electric vehicles where engine noise is replaced by motor noise which is a tonal noise at very high frequency. This makes the improvement of tire noise levels quintessential for good cabin acoustic feel. This demands a proactive approach to develop low noise tire platforms for future mobility by leveraging research tools and best practices in the industry.
Technical Paper

Advanced CAE Methods for NVH Development of High Speed Electric Axle

2020-09-30
2020-01-1501
The rate in the electrification of vehicles has risen in recent years. With intensified development more and more attention is paid to the noise and vibration in such vehicles especially from the EDU (Electric Drive Unit). In this paper the main NVH simulation process of a high-speed E-axle up to 30,000 rpm for premium class vehicle application is presented. The high speed, high-power density and lightweight design introduces new challenges. Benchmarking of different EDUs and vehicles leads to targets which can be used at the early stage of development as subsystem targets. This paper shows the CAE methodology which can be used to verify the design and guarantee the target achievement. Using CAE both source and structure can be optimized to improve the NVH behavior.
Technical Paper

On Prediction of Automotive Clutch Torsional Vibrations

2020-09-30
2020-01-1508
Automotive clutches are prone to rigid body torsional vibrations during engagement, a phenomenon referred to as take-up judder. This is also accompanied by fore and aft vehicle motions. Aside from driver behaviour in sudden release of clutch pedal (resulting in loss of clamp load), and type and state of friction lining material, the interfacial slip speed and contact temperature can significantly affect the propensity of clutch to judder. The ability to accurately predict the judder phenomenon relies significantly on the determination of operational frictional characteristics of the clutch lining material. This is dependent upon contact pressure, temperature and interfacial slip speed. The current study investigates the ability to predict clutch judder vibration with the degree of complexity of the torsional dynamics model. For this purpose, the results from a four and nine degrees of freedom dynamics models are compared and discussed.
Technical Paper

Numerical Analysis of the Influences of Wear on the Vibrations of Power Units

2020-09-30
2020-01-1506
Numerical Analysis of the Influences of Wear on the Vibrations of Power Units Yashwant Kolluru, Rolando Doelling eBike Department Robert Bosch GmbH Kusterdingen, Germany yashwant.kolluru@de.bosch.com rolando.doelling@de.bosch.com Lars Hedrich Institute of Informatics Goethe University Frankfurt Frankfurt, Germany hedrich@em.informatik.uni-frankfurt.de The prime factor, which influences vibrations of electro-mechanical drives, is wear at the components. This paper discusses the numerical methods developed for abrasion, vibration calculations and the coupling between wear and NVH models of drive unit. Wear is a complex process and understanding it is essential for vibro-acoustics. The paper initially depicts finite element static model used for wear calculations. The special subroutines developed, aids in coupling the wear equations, various contact and friction formulations to the numerical model.
Technical Paper

The In-Depth PHEV Driveline Torsional Vibration Induced Vehicle NVH Response Study by Integrated CAE/Testing Methodology

2020-09-30
2020-01-1507
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 the testing;thirdly,the NTF/VTF from the mount/suspension force exertion points to vehicle response points were measured off trimmed body impact testing, to create structural TPA model,that way,each transfer path contribution to the response point could be predicted and overall response can be synthesized from all paths;fourthly,the above-mentioned driveline model,combined the excitation on each cylinder considering the gas torque/inertia torque and motor average torque,was well calibrated to predict the mount/suspension force/critical rpm fluctuation/vibration;finally,it was validated that CAE results correlate very well to measurement outcome for defined loadcase, and that can be adopted to phev driveline/vehicle NVH development from the very start of vehicle development phase so as to expedite vehicle NVH developing process.
Technical Paper

Characterisation of Brake Creep Groan Vibrations

2020-09-30
2020-01-1505
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.
Technical Paper

NVH Comfort of Range Extenders for Electric Vehicles

2020-09-30
2020-01-1551
The most appreciated driving characteristics of electric vehicles are the quietness and spontaneous torque rise of the powertrain. The application of range extenders (REX) with internal combustion engines (ICEs) to increase the driving range is a favourable solution regarding costs and weight, especially in comparison with larger battery capacities. However, the NVH integration of a REX is challenging, if the generally silent driving characteristics of electric vehicles shall remain preserved. This paper analyses key NVH aspects for a REX design and integration to fulfil the high expectations regarding noise and vibration comfort in an electric vehicle environment. The ICE for a REX is typically dimensioned for lower power outputs, incorporating a low number of cylinder units, which is even more challenging concerning the NVH integration. The basic REX concept is evaluated by considering power and fuel efficiency demands in combination with an interior noise forecast.
Technical Paper

Linking Body-In-White and Trimmed Body Dynamic Characteristics in view of Body-In-White Mode Shape Target Setting

2020-09-30
2020-01-1553
Target setting at Body-In-White (BIW) level is typically done for natural frequencies of global modes. Target values are commonly set based on experience or from benchmark studies with competitor vehicles. A link between these targets at BIW level and the vibro-acoustic targets at Trimmed Body (TB) level is not yet well established. Therefore, it is not always guaranteed that the TB targets will be met when the targets at BIW level are reached. Also, the other way around, not reaching a frequency target for a certain BIW mode does not necessarily imply that TB targets will not be met. Hence, there is a clear need for getting more insights in the relation between BIW dynamic properties and TB vibration behavior. In this paper techniques will be presented that establish the link between BIW and TB dynamic behavior. In addition, a large DOE campaign has been carried out to further link these dynamic properties to specific areas in the body design.
Technical Paper

Fault Diagnosis of an Engine through Analyzing Vibration Signals on the Block

2020-09-30
2020-01-1568
Unpredictable faults oriented from ambiguous reasons could occur in an engine of a vehicle. However, there are some symptoms from which an engine is working abnormally before the engine is stalled by faults. In this paper, methods for diagnosis of engine faults by using vibrations are proposed. Through bench tests, to extract features for fault diagnosis, various samples with normal and abnormal conditions are prepared and vibration signals from the block of an engine are measured and analyzed. To consider cost and performance of a sensor, vibrations from a knock sensor signal as well as accelerometers are analyzed. Measured vibration signals are synchronized with signal of the crank position sensor and analyzed to detect which event is involved. Modulation analysis and Hilbert transform are applied to extract features representing the symptoms of engine faults and to indicate when the abnormal event happens, respectively.
Technical Paper

Design of a Multiwaves Vibration Filtering

2020-09-30
2020-01-1560
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.
Technical Paper

Time Domain Full Vehicle Interior Noise Calculation from Component Level Data by Machine Learning

2020-09-30
2020-01-1564
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), today these approaches are not widely applied in the field of vehicle Noise, Vibration and Harshness (NVH). Works combining ML and NVH mainly discuss the topic with respect to psychoacoustics, traffic noise, structural health monitoring and as improvement to existing numerical simulation methods. Vehicle interior noise is a major quality criterion for today’s automotive customers. 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 conduct the prediction process for a steering system.
Technical Paper

Development of the Active Sound Generation Technology using Motor Driven Power Steering System

2020-09-30
2020-01-1536
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.
Technical Paper

Extended Solution of a Trimmed Vehicle Finite Element Model in the Mid-Frequency Range

2020-09-30
2020-01-1549
The acoustic trim components play an essential role in Noise, Vibration and Harshness (NVH) behavior by reducing both the structure borne and airborne noise transmission while participating to the absorption inside the car and the damping of the structure. Over the past years, the interest for numerical solutions to predict the noise including trim effects in mid frequency range has grown, leading to the development of dedicated CAE tools. Finite Element (FE) models are an established method to analyze NVH problems. FE analysis is a robust and versatile approach that can be used for a large number of applications, like noise prediction inside and outside the vehicle due to different sources or pass-by noise simulation. Typically, results feature high quality correlations. However, future challenges, such as electric motorized vehicles, with changes of the motor noise spectrum, will require an extension of the existing approaches.
Technical Paper

Reinforcement of Low-Frequency Sound by Using a Panel Speaker Attached to the Roof Panel of a Passenger Car

2020-09-30
2020-01-1570
The woofer in a car should be large to cover the low frequencies, so it is heavy and needs an ample space to be installed in a passenger car. The geometry of the woofer should conform to the limited available space and layout in general. In many cases, the passengers feel that the low-frequency contents are not satisfactory although the speaker specification covers the low frequencies. In this work, a thin panel is installed between the roof liner and the roof panel, and it is used as the woofer. The vibration field is controlled by many small actuators to create the speaker and baffle zones to avoid the sound distortion due to the modal interaction. The generation of speaker and baffle zones follows the inverse vibro-acoustic rendering technique. In the actual implementation, a thin acrylic plate of 0.53ⅹ0.2 m2 is used as the radiator panel, and the control actuator array is composed of 16 moving-coil actuators.
Technical Paper

CAE Support to Vehicle Audio Installation Issues

2020-09-30
2020-01-1575
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.
Training / Education

Vibration Analysis Using Finite Element Analysis (FEA) Web Seminar RePlay

Anytime
Finite Element Analysis (FEA) has been used by engineers as a design tool in new product development since the early 1990"s. Until recently, most FEA applications have been limited to static analysis due to the cost and complexity of advanced types of analyses. Progress in the commercial FEA software and in computing hardware has now made it practical to use advanced types as an everyday design tool of design engineers. In addition, competitive pressures and quality requirements demand a more in-depth understanding of product behavior under real life loading conditions.
Technical Paper

Vibration in Automobile Engines

1928-01-01
280048
In this article the author presents analytical methods for determining the unbalanced inertia force and the tangential effort in a line engine. These methods are thought to be of interest for investigation of the effects of various engine design-features on its vibration characteristics. An equation for the resultant reciprocating force is set forth and methods of expressing the inertia and fluid-pressure torque are given. The determination of minimum and maximum resultants and the balance of inertia and fluid-pressure torques are other topics dealt with. The results of a series of analyses are incorporated in tabular form.
Technical Paper

The Angular Distortion of Crankshafts

1928-01-01
280049
REFERENCES are given to many articles and books on crankshaft vibration, written in both English and German. As published experimental data on deflections are lacking, the authors obtained an engine with four crankshafts, having crank-arms with different cross-sections, and measured the deflections under static load. Deflections in various parts of the shafts are analyzed and compared, and a formula is developed for the deflection in the long crank-arms of the shaft.
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