Browse Topic: Noise, vibration, and harshness standards and regulations

Items (244)
This SAE Standard sets forth measurement procedures and instrumentation to be used for determining a “representative” sound level during a representative time period at selected measurement locations on a construction site boundary. The document is not intended for use in determining occupational hearing damage risk. Determination of a representative time period is left to the judgment of the user.
OPTC3, Lighting and Sound Committee
Frequency Inspection of Brake System Components2019-01-21179/15/2019
Frequency inspection has long been a tool utilized by manufacturers of brake system components as a means of quality control. This is important to combat perceived defectiveness of a system that experiences issues, such as brake squeal, as well as to identify actual defects in the parts going out to customers. Every component has its own resonance frequencies based on the dynamics of that component. Knowledge of the resonance frequencies of each component provides insight that can prevent manufacturers from sending out defective units, whether they be perceived defects or actual defects. NVH engineers who understand these phenomena perform theoretical analysis and acquire experimental data in the lab to gain insight into their parts that will eventually be produced on the assembly line. Unfortunately, the frequency requirements, and the consequences thereof, defined by the NVH engineers can still remain somewhat of a mystery to the manufacturing engineers who are tasked with applying them. Oversights in specifications can lead to avoidable scares that lead to delays and downtime. For example, differences in accelerometer placement on a brake rotor from the lab to the assembly line can lead to issues such as variable frequency reporting. This leads to inaccurate data reporting, which leads to poor Gage R&R. A basic understanding of vibration and how to analyze data would allow the manufacturing engineer to troubleshoot such an issue and prevent unnecessary delays. This paper will attempt to take these concepts beyond the specification sheet and into the science and mathematics behind the dynamics of the different components of the total brake system. The knowledge gleaned from this analysis allows for intelligent decision making for go/no-go on the production line, as well as root cause analysis in the lab.
Cagle, Robert
Design Optimization of Differential Bevel Gear for NVH Improvement2019-01-15526/5/2019
With fast pacing development of automobile industry and growing needs for better driving experience, NVH performance has become an important aspect of analysis in new driveline product development especially in hybrid and electric powered vehicles. Differential bevel gear has significant role in the final drive. Unlike parallel axis gears such as spur or helical gear, bevel gear mesh shows more complicated characteristics and its mesh parameters are mostly time-varying which calls for more extensive design and analysis. The purpose of this paper is to conduct design study on a differential bevel gear unit under light torque condition and evaluate its NVH characteristics. Unloaded tooth contact analysis (UTCA) of those designs are conducted and compared for several design cases with different micro geometry to investigate their pattern position and size variation effects on NVH response. Loaded tooth contact analysis (LTCA) that is based on semi-analytical and semi-FE method is used to compare other mesh parameters such as mesh point, line-of-action (LOA) and mesh stiffness. For experimental study, several 11x16 gear pairs are tested at multiple gear positions to study the robustness of each micro geometry design. Both pattern and transmission error(TE) are correlated and compared. Result of this study proves the effectiveness and accuracy of modeling and supports the design optimization predictions.
Shi, ZhenghongChen, JuiKolivand, MohsenSun, ZhaohuiKopp, GregoryPeng, Ying
Application of Model Order Reduction to Nonlinear Finite Element Tire Models for NVH Design2019-01-15076/5/2019
In current practice, tire development and testing are typically experimentally driven. However, as the need to simultaneously optimize multiple noise vibration and harshness (NVH) performance criteria increases and development cycles become shorter, predictive numerical simulation techniques are becoming necessary. In addition, many tire performance areas are coupled and therefore the experimental approach often lacks detailed insights which numerical simulations can provide. Currently, no industrially applicable fully predictive high-fidelity numerical approach that incorporates the use of nonlinear Finite Element (FE) tire models for NVH design is available in literature. Therefore, a fully predictive numerical simulation approach that predicts the rolling of a tire over a coarse road surface is described in this work. The proposed approach allows to predict the dynamic contact- and hub forces that arise during rolling without the need for experimental data. Based on these results the NVH performance of a specific tire design can be assessed and optimized. One of the main drawbacks of using nonlinear FE tire models for NVH design, is the large computational cost associated with running the numerical simulations. Therefore, application of a nonlinear Model Order Reduction (MOR) and hyper-reduction technique to the nonlinear FE tire models is described in this work as well. It is shown that application of the MOR and hyper-reduction techniques greatly reduces the total computational time and costs, leading to acceptable computational times for engineering practice. The simulation results show good correspondence with experimental data. This confirms the potential of this efficient predictive numerical simulation approach as a viable alternative to the experimental based approach in tire NVH design.
De Gregoriis, DanielNaets, FrankKindt, PeterDesmet, Wim
New Half Shaft Bench Test Methodology for NVH Characterization2019-01-15586/5/2019
The main purpose of this paper is to develop a reliable bench test to understand the vibratory behavior of the half shafts under applied torque comparable to an idle condition. In some cases, the half shaft path is a major factor influencing the idle vibration in the vehicle. At idle condition vehicle vibrations are caused by engine excitation and then they pass through different paths to the body structure. Half shaft manufacturers generally characterize shaft joints for their frictional behavior and typically there is no data for vibration characteristics of the half shaft under idle conditions. However, for predictive risk management, the vibratory behavior of the half shaft needs to be identified. This can be achieved from measured frequency response functions under preloaded test conditions. This bench test enables manufacturers to conduct comprehensive design of experiments on the impact of powertrain vibration input while transmitting through the half shaft into the vehicle system. This method enables the study of the half shaft at the component level, because studying the half shaft at vehicle level is difficult since other paths are present. This paper describes the bench test methodology and presents certain boundary condition challenges of the half shaft measurements, the design of the test rig and the preliminary joint behavior results on the test bench.
Siavoshani, SaeedVesikar, Prasad BalkrishnaYuan, WeiAbbas, AhmadSturla, Francisco Antonio
Gear System Parameters and Its Influence on Gearbox Noise2019-01-15626/5/2019
Tonal noise due to gears is one of the fundamental noise problems in a gearbox. Gear tooth deflections generate dynamic forces that lead to unwanted load fluctuations, thus noise. Different factors that are considered to control this noise, some to mention like proper gear macro design, microgeometry corrections, and housing compliance. However, identifying the appropriate variable as a measure of contribution to the overall response helps in getting more accurate remedial solutions. Some outputs to track are different harmonic components of TE, temperature effects, components of forces, rim compliance and friction. For evaluation, usually, the amplitudes of individual harmonics of transmission error are related to the respective orders of the noise levels assuming it as one of the primary excitation parameters of gear noise. In this paper, a brief overview of TE and its harmonic distribution is discussed with the example of an ideal gear mesh model and then quantifying TE with the introduction of mesh misalignment. The effect of providing additional microgeometry corrections to compensate for the misalignment is also discussed. The study in this paper discusses the influence of parameters that are associated with gear whine and will serve as a guideline for the optimizing the gear design. The analysis was performed on a simple external helical gear mesh model in LDP tool for generating loads and TE. Moreover, the radiated noise from the flexible housing was also monitored to study the influence of different parameters on the sound power levels. Some additional results were evaluated with an in-house developed tool as well. The studies performed in this paper will help in identifying the parameters for transmission durability & NVH also their importance in designing quiet and robust gearbox.
Dewangan, Yogesh KumarNair, Pranoy SureshbabuNair, Dipin
Driveline NVH Integration of An NA Truck Program2019-01-15596/5/2019
In the current automotive industry, it is common that the driveline subsystem and components are normally from different automotive suppliers for OEMs. In order to ensure proper system integration and successful development of driveline system NVH performances, collaboration efforts between OEMs and suppliers are very demanding and important. In this paper, a process is presented to achieve successfulness in developing and optimizing vehicle integration through effective teamwork between a driveline supplier and a major OEM. The development process includes multiple critical steps. They include target development and roll down, targets being specific and measurable, comprehension of interactions of driveline and vehicle dynamics, accurate definition of sensitivity, proper deployment of modal mapping strategy, which requires open data sharing; and system dynamics and optimization. More specially, the supplier can work with OEM to seek the most cost-effective solutions, through tuning the driveline system dynamics to provide "quiet" frequency zone against vehicle sensitivity, to avoid normally needed costly suspension changes. Two case studies of a pick-up vehicle driveline program integration are used in this paper to illustrate the effectiveness of the development process. The paper also presents the approach used to effectively and efficiently minimize risks for all of the complexities in the program where the complexity is tremendous.
Peng, YingShi, ZhenghongFolts, ChristopherKopp, GregorySun, ZhaohuiSandstrom, Alexander
Target Setting Process for Hybrid Electric Drives Using TPA, Jury Study, and Torque Management2019-01-14536/5/2019
The idea of improved efficiency without compromising the “fun to drive” aspect has renewed the auto industry’s interest toward electrification and hybridization. Electric drives gain from having multiple gear ratios which can use advantageous operating set points thus increasing range. Furthermore, they benefit significantly from frequent decelerations and stopping as is experienced in city driving conditions. To recuperate as much energy as possible, deceleration is done at high torque. This presents an interesting but serious sound quality issue in the form of highly tonal whine harmonics of rapidly changing gears that do not track with vehicle speed thus being objectionable to the vehicle occupants. This paper presents an NVH target setting process for a hybrid electric transmission being integrated into two existing vehicles, one belonging to the premium segment and another aimed at enthusiasts with off-road applications. The demand for power has shifted from mechanical domain into electrical domain, and as such, the solution to electric drive NVH issues also lay partly, in the way these drive systems are calibrated. A time-domain Transfer Path Analysis (TPA) model was developed for both vehicles, by virtually installing the hybrid transmission into the vehicle, thus predicting interior noise in several gears and simulating the brake regen coast downs at varying torque levels. Road and wind noise masking was added to these predictions taking care that the summations were correctly done at same vehicle speeds for which a program was written using a commercially available numerical computing tool. Extensive jury studies were then conducted to determine NVH no-fly zones and the torque management strategy for the two vehicles during brake regen events. Requirements and strategy for the two vehicles were different since they presented different levels of road and wind noise masking. To validate the NVH targets, another jury compared the finalized strategy with a premium target vehicle fitted with a similar hybrid system. This target-setting approach was useful in getting an upfront idea of the NVH risks without any system modifications. It then circumvented the need of re-developing expensive acoustic package and/or gear optimization that would be otherwise needed to mitigate the risks, with co-operation from calibration teams, while still being able to meet their regenerative braking targets in every gear for the two vehicles.
Singh, VinodParbat, AniketCharan, Anil
Interior Floor Engineering: The Dynamic-vs-Static-Stiffness Compromise2019-01-14936/5/2019
When it comes to the design of multi-functional automotive interior floors, engineers face the challenging conflict between a dynamically-soft, NVH performing treatment, and a statically-stiff construction, which increases the perception of solidity. Nowadays, the former requirement is well-specified and advanced CAE tools exist to support performance prediction and engineering of the construction. On the contrary, neither well-established requirements specify the compressional performance, nor defined CAE processes are available to support the engineer in its prediction. In this context, the aim of this paper is twofold. Firstly, insightful conclusions about the compression behavior of typical interior floor materials are drawn by means of tests carried out both at sample- and part-level. Such an analysis allows highlighting a clear direction towards meaningful assessment of the mechanical characteristics of the floor. Secondly, the paper focuses on how CAE tools can support part-level engineering in dealing with the dynamic vs static-stiffness compromise. Specifically, simulation results show that non-linear finite element simulations can support an accurate assessment of the floor deflection during compression, and yet they can be exploited in combination with well-established tools for NVH assessment.
Pezzani, FlavioGodano, PhilippeRonzio, FrancescaD'Amico, Roberto
System Interactions Affecting NVH Performance of an Electric Vehicle Drivetrain2019-01-15456/5/2019
The paper will present an integrated approach to system NVH analysis, which gives an insight into the system response in an EV driveline due to electrical and mechanical excitations; namely rotor mechanical imbalance, electrical machine torque ripple, and stator radial force shapes. The paper will address the fact that, as part of a practical design exercise, different subsystems and components may achieve design maturity at different times. It is therefore important to understand to what extent various drivetrain components may be considered in isolation, and at what point it becomes necessary to consider the interactions present in the full system. The paper will compare predicted NVH performance of a representative EV traction motor when different boundary conditions are considered; for example, when considering the motor being bested in isolation as part of a typical test setup, and when included in a representative drivetrain. For each configuration, the response to mechanical and electro-mechanical noise mechanisms will be assessed, and the fidelity of simulation required to achieve an appropriate engineering insight will be considered. From these studies, the best practice for the assessment of NVH as part of a holistic design process will be discussed. Consideration will be made of the factors which may influence the choice of simulation approach; for example, the level of design maturity, the availability and reliability of system data, and the design targets which are to be addressed.
Michon, MelanieHolehouse, RobertShahaj, AnnabelJafarali, HishamJanakiraman, Venkatakrishna
Robust NVH Engineering Using Experimental Methods - Source Characterization Techniques for Component Transfer Path Analysis and Virtual Acoustic Prototyping2019-01-15426/5/2019
A major challenge in automotive NVH engineering is to approach complex structure-borne sound and vibration problems with sufficient accuracy but reasonable experimental effort. Typical issues encountered are poor correlation between objective component performance criteria tested for during bench validation and corresponding subjective targets evaluated during system validation in the actual vehicle. Additional challenges arise from the need to impose assumptions on sophisticated physical vibration problems to reduce the complexity to a level feasible for conventional experimental test methods. This paper addresses all mentioned issues by elaborating on a system NVH engineering approach employing Virtual Acoustic Prototyping (VAP) (related to what is now often called component Transfer Path Analysis) to synthesize time domain sound and vibration responses of vibrating machinery operated in a virtual vehicle environment. One crucial step of VAP is to characterize the strength of vibrating machinery by independent quantities at the significant coupling degrees of freedom (DoF). This study puts special focus on the measurement of free velocity, suitable for machinery operated when resiliently mounted as per ISO 9611, and the in-situ measurement of blocked forces, applicable for sources connected to any type of receiving structure during operation, as per ISO/DIS 20270. In order to reduce complexity of the underlying measurements this paper investigates the possibility of using collocated sensor arrays and methods to validate assumptions imposed to abstract away from rotational coupling DoF. An electric power steering (EPS) system inducing vibrations into a sub-frame-type structure is considered as a representative automotive source-receiver installation to investigate the feasibility of free velocity and in-situ blocked force approach with respect to independent source characterization for component Transfer Path Analysis (TPA) and VAP. The obtained Virtual Acoustic Prototype is expanded using an algorithm to synthesize realistic time domain data, enabling NVH engineers to conduct reliable objective and subjective design evaluations.
Wienen, KevinSturm, MichaelMoorhouse, AndyMeggitt, Joshua
NVH Aspects of Electric Drive Unit Development and Vehicle Integration2019-01-14546/5/2019
The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle-level fuel consumption. Specifically, the use of electrified propulsion systems is expected to play an increasingly important role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. This will also include a strong growth in the global demand for electric drive units (EDUs). The change from conventional vehicles to vehicles propelled by EDUs leads to a reduction in overall vehicle exterior and interior noise levels, especially during low-speed vehicle operation. Despite the overall noise levels being low, the NVH behavior of such vehicles can be objectionable due to the presence of tonal noise coming from electric machines and geartrain components as well as relatively high shares of road/wind noise. In order to ensure customer acceptance of electrically propelled vehicles, it is imperative that these NVH challenges are understood and solved. This paper discusses various aspects of the EDU NVH development process. This will include a discussion of the NVH target cascading methodologies for EDUs, followed by a description of the EDU development and vehicle NVH integration process. Utilizing examples, specific aspects of EDU design to assure acceptable NVH behavior from the EDU will be discussed. The use of advanced simulation techniques for electric machine noise as well as geartrain-related noise will be demonstrated using examples. Finally, aspects of EDU “source” noise/vibration measurements and integration into the vehicle to assure refined vehicle-level NVH behavior will be illustrated using examples from relevant case studies.
Wellmann, ThomasTousignant, ToddGovindswamy, KiranTomazic, DeanSteffens, ChristophJanssen, Peter
Integrated Multi-Physics Simulation for Full-Vehicle Low Frequency NVH Optimization in HEVs2019-01-14556/5/2019
The recent automotive industry trend towards electrification has created new challenges for NVH engineers. These challenges stem from new powertrain architectures and their complex interactions, the governing control strategies which aim to optimize energy management, and new unmasked sources of excitation. Additionally, vehicle manufacturers are attempting to reduce hardware testing in order to rapidly satisfy increasing production demand and to minimize its costs. Hence, to meet the above-mentioned challenges up front in the development process of Hybrid Electrical Vehicles (HEVs) while balancing competing design objectives of drivability, durability and NVH, a simulation-led design and optimization is required. NVH problems are often the result of mechanisms that originate through complex interactions between different physical domains (flow, electromagnetic, structural/mechanical, control logic, etc.) and the assembly of individual components into a complete system. Therefore, accurate system-level integrated models are becoming a requirement to solve modern NVH problems. Combining the optimal balance between simulation and experimental data, this article describes a joint effort between Ford and Gamma Technologies to develop a general methodology to perform full-vehicle low frequency NVH analysis. Using GT-SUITE software, a non-linear multi-physics simulation model of a rear wheel drive HEV was created. The model was exercised to accurately evaluate the effects of powertrain control strategy and component selection on low-frequency NVH performance during a tip-in regeneration, downshifting and in-gear acceleration maneuvers while minimizing the computational cost.
Gomez, Llorenc ForasteZeman, JonathanLiu, Jack
Determining Vibro-Acoustic Characteristics and Structural Damping of an Elastic Monolithic Panel2019-01-15386/5/2019
Evaluations of the dynamic and acoustic responses of panels, partitions, and walls are of concern across many industries, from building home appliances, planning meeting rooms, to designing airplanes and passenger cars. Over the past few decades, search efforts for developing new methodologies and technologies to enable NVH engineers to acquire and correlate dynamically the relationship between input excitations and vibro-acoustic responses of arbitrary-shaped panels has grown exponentially. The application of a particular methodology or technology to the evaluation of a specific structure depends intimately on the goals and objectives of the NVH engineers and industries. In this work, we present the comparisons between the traditional modal analyses for structural vibrations together with sound intensity measurements of sound radiation and a laser-assisted Helmholtz equation least squares (HELS) method [1, 2, 3, 4] to characterize the dynamic and acoustic responses of an arbitrarily shaped structure subject to non-contact acoustic excitations. Input data for the latter include the normal surface velocities measured at a finite number of points on the surface of the structure that are accessible to a laser beam, and the acoustic pressures measured at a few points in the near field. With these input data, we will be able to reconstruct the normal surface velocity, the surface acoustic pressure, the normal surface acoustic intensity distributions over the entire structure, dimensionless structural damping ratio spectrum, sound transmission losses (STL), and sound transmission paths, etc. These data enable engineers to acquire a comprehensive understanding of the vibro-acoustic characteristics of any arbitrarily shaped vibrating structure, which can lead to the most cost-effective NVH reduction.
Figueroa, AntonioWu, SeanChen, Lingguang
Open-Access Testbench Data for NVH Benchmarking of E-Machines under Electromagnetic Excitations2019-01-14596/5/2019
This paper presents an experimental setup dedicated to the analysis of noise and vibration due to Maxwell magnetic forces in electrical machines, a significant NVH source in hybrid and electric vehicles traction motors. Both electromagnetic excitations and structural response of the electrical machine are simplified to provide the first public benchmark of e-NVH phenomenon (electromagnetic Noise, Vibration, Harshness). The paper first describes how the testbench is designed and tested in order to reduce as much as possible modelling and experimental uncertainties. A Permanent Magnet Synchronous Machine topology used in EV/HEV applications is used to illustrate tooth modulation effect and interaction between radial and tangential force-induced vibrations, and designed to generate the resonance of several stator structural modes with simplified electromagnetic loading (open-circuit case). A larger air gap allows the insertion of a fine search-coil network to measure time and space distribution of the air-gap flux density and resulting Maxwell stress harmonics. Accelerometers are placed on stator tooth tips to capture tooth bending motion, as well as on the outer yoke of the stator. Besides vibration measurements, sound pressure and sound power level measurements are carried. Then, some of the key measurement results are presented including Experimental Modal Analysis, Operational Deflection Shapes, and Order Tracking Analysis, spectrograms and spatiograms, Sound Pressure Level and Sound Power Level measurements. The origin of the different NVH harmonics are analyzed and their physical origin is detailed. All the benchmark data is available in open access and can be used to compare different multiphysic simulation strategies of e-NVH in terms of accuracy and computing time, such as analytic, semi-analytic, numerical and hybrid methods using during electromagnetic, structural mechanics and acoustic calculations. The benchmark will be used in further work to study the most common noise mitigation strategies used in EV/HEV electric motors such as skewing, notching, pole and slot shaping, and harmonic current injection.
Devillers, EmileDegrendele, KarineHecquet, MichelLecointe, Jean-PhilippeLe Besnerais, JeanCousin, Guillaume
A Case Study on Golf Car Powertrain NVH Sources and Mitigation Methods2019-01-14786/5/2019
The golf market has remained flat in North America. Whereas, it has grown worldwide. A trend is seen where the number of young adults and adults over the age of 65 years involved with the game has increased. The demographics in golf showing the most growth also have high standards for the operation of the golf car. They have transcended their expectations to align with some of the qualities expected of automobiles. There is a shift in consumer expectations. Moreover, the market competition has also increased. This drives the OEMs to deliver refined golf cars with NVH being a key aspect in development. This paper showcases a recent study to improve the powertrain N&V performance of an internal combustion engine golf car. Primarily, a test-based approach is followed. Chassis rolls and on road testing are performed for benchmarking and target setting. System and component tests are performed to root cause issues. The tests further help to provide input for mitigation methods for application on the golf cars. Structural modifications address structure-borne noise and perceived vibration. Component modifications and additions address three key aspects. They reduce air-borne noise, decrease overall SPL, and improve sound quality for brand identity. These mitigation techniques are applied on the golf car. Jury evaluations correlated with on-road testing results for golf car improvement. The improvements were in both sound quantity and sound quality.
Carter, StevenBuczek, KennethClark, AdamPathak, Mayuresh
Benefit of a Lightweight Frunk2019-01-14566/5/2019
Due to the increasing number of battery electric vehicles (BEVs), the engineering fields regarding driving comfort and NVH issues are becoming more and more challenging: many new factors affect the development of BEVs NVH package. The noise sources related to the powertrain are different from the traditional ones of internal combustion engines, for instance due to the presence of tonal components, strong harmonics and potential whining noise. To satisfy NVH specifications and the need for lightweight solutions to increase driving range, it is important to mask as much as possible the noise coming from the engine bay with materials both lightweight and acoustically performing. Moreover, for electric vehicles new interesting solutions are possible with the introduction of new components that do not find room under the hood of ICE or hybrid vehicles. These components, if properly designed, could lead to significant NVH benefits. The present paper reports the NVH effects of one of these new components, the frunk, a small compartment inside the engine bay, functionally similar to the trunk. In this paper, the design-by-simulation of a frunk is described. By means of simulation both acoustic and mechanical requirements are analyzed. First, FE mechanical simulations are used to ensure that the right design to satisfy static and dynamic load conditions with a lightweight material is found. After this, the potential NVH benefits of adopting -for the frunk- a porous textile material in comparison to a glass-fiber reinforced plastic are assessed. Focus is also put on the possibility to reduce traditional engine bay treatments when an acoustic frunk is adopted. The model used in NVH simulations is a simplified engine bay mock-up, in which a simplified frunk was inserted. An acoustic point source excitation was placed where an e-motor is normally mounted. The effects of the frunk were judged simulating acoustic transfer functions (ATFs) in several positions, corresponding to microphones placed inside and outside the engine bay cavity.
Di Marco, FedericoPezzani, FlavioDaving, AndreasMazzarella, Luca
Structural Vibration and Acoustic Analysis of a 3-Phase AC Induction Motor2019-01-14586/5/2019
This paper aims to study the NVH and acoustic performance of a 3-phase AC induction motor in order to develop an approach to reduce the magnetic component of noise from an electric motor in an electric vehicle (EV). The final goal of this project is to reduce the magnetic component of sound from the motor by making modifications to the end bracket of the motor housing. EVs are being considered the future of mobility mainly due to the fact that they are environment-friendly. As many companies are already investing in this technology, electric drives are set to become extremely popular in the years to come. The heart of an EV is its motor. Modern electric vehicles are quiet, furthermore with the lack of an IC engine to mask most sounds from other components, the sound from the electric motor and other auxiliary parts become more prominent. The primary source of electromagnetic noise in a motor arises from magnetic flux variations in the air gap which interfere with the resonant frequencies of the stator core. These flux variations result in a time-varying force that acts on the stator core or teeth and causes it to deform. This paper studies the radial and tangential components of this force and how these structural vibrations can be dampened by using a modified end bracket with properties that can help reduce the overall sound radiated by the motor. The paper shows a process to analyze the sound radiated from an electric motor in three broad steps. First, an impact hammer test is performed on the stator and assembled motor to analyze its resonant frequencies. Second, the operational deflection shapes of the motor in the operating condition are extracted to visualize the housing deformation and identify resonant frequencies being excited. Finally, a sound intensity analysis is conducted to calculate sound pressure levels at different frequencies.
Krishnasarma, AnandTaylor, AllanBaqersad, JavadPoozesh, Peyman
Model Verification of CAE with NVH-Test Acting on Downsized Car Engines2019-01-15506/5/2019
Today’s trend of combustion engine development for cars is characterized with; high torque, low engine speed, low weight, high degree of cyclic irregularity, low excitation frequency due to fewer cylinders active e.g. 4-cylinder or less. This implies in respect of vibrations that it is crucial to control powertrain rigid body modes and place these were they cannot be reached and induced by the low exciting harmonic frequencies for low engine speeds or idling. It is also important to control the overall flexible vibration modes. A mathematical CAE model is created in simulation software AVL-EXCITE in order to handle the vibration phenomenon as a first step. But it is absolutely necessary to “verify” these models with real measurements in respect of NVH and if needed upgrade the CAE model if there are detected deviations. The NVH-test is done with testing tool DEWESoft. The purpose of below paper is to do model verification on a concrete example in respect of powertrain vibrations. Volvo Cars in-line 4-cylinder VEA diesel engine in rig installation is the object for the paper of model verification. Method of this work has been to do simultaneously NVH measurements of vibrations, torque and cylinder pressure traces during different engine load conditions. Also bump test with a modal hammer has been done in order to find rigid body mode frequencies. The measured cylinder pressure is applied as input to the simulation model in order to have consistent input load between test and simulation. This is important when comparing the output vibrations. Verify and compare crank angle based time domain vibrations signals from CAE model with NVH-testing on a real engine. This is the results of the work.
Rönnqvist, UrbanRibarits, Janos
Reducing Vehicle Interior NVH by Means of Locally Resonant Metamaterial Patches on Rear Shock Towers2019-01-15026/5/2019
Stringent regulations for CO2 emissions and noise pollution reduction demand lighter and improved Noise, Vibration Harshness (NVH) solutions in automotive industries. Designing light, compact and, at the same time, improved NVH solutions is often a challenge, as low noise and vibration levels often require heavy and bulky additions, especially to be effective in the low frequency regime. Recently, locally resonant metamaterials have emerged among the novel NVH solutions because of their performant NVH properties combined with lightweight and compact design. Due to the characteristic of stop band behavior, frequency ranges where free wave propagation is inhibited, metamaterials can beat the mass law, be it at least in some tunable frequency ranges. Previously the authors demonstrated how metamaterials can reduce the vibrations in a simplified shock tower upon shaker excitation. In this work, the authors apply the metamaterial concept on the real rear shock towers of a vehicle. In order to be able to benchmark the solution, a test vehicle is chosen, which is equipped in its commercial version with a 1.46 kg tuned vibration absorber (TVA) on each of the rear shock towers as NVH solution. It is shown that the metamaterial solution allows to achieve similar interior NVH performance, while reducing the added mass by 48%. The metamaterial additions are realized through additive manufacturing and they are designed to be effective around 190 Hz, as was the case for the original solution. Both experimental results and numerical validation of a road test are presented.
Sangiuliano, LucaClaeys, ClausDeckers, ElkeDe Smet, JasperPluymers, BertDesmet, Wim
Automotive Engineering: March 201919AUTP033/1/2019
Rethinking the HUD Advanced tech solutions move toward augmented reality to bring greater capability to head-up displays. Motor matters New designs and materials are key to the next generation of electric machines for EV propulsion. Harnessing the power of Sim Serious cost savings could come from eliminating vehicle- and systems-level tests. Powerful simulation tools may be the only way to tackle the increasing complexity in mobility development. An OBE for the SAE Meet Paul Mascarenas-SAE International's 2019 president. He's a staunch advocate for professional development for engineers amid the mobility industry's transformation. Solving the propulsion puzzle Must-attend expert panels at SAE's WCX '19 will cover the propulsion-tech future like no other. Editorial Kill the EV tax credit by 2025 SAE Standards News SAE and Synopsys collaborate on cyber study Supplier Eye New Co. vs. Old Co. What We're Driving Supra's revival is Toyota's spin on German engineering 2020 Explorer is the first product to emerge-more quietly-from Ford's newest NVH lab Nissan concept sport sedan is all-electric, driver-optional MEET a new propulsion proposition for Mahle Continental's new CTO to lead retooled R&D pillar New V8, big towing, trick features and tech for 2020 Chevy Silverado HD FCA debuts new Ram Heavy Duty pickups 2020 Ford Super Duty debuts all-new OHV V8 2019 Chevrolet Blazer just right for the voracious SUV market Q&A Mazda's Masahiro Moro
BIOT’s Parameters Evaluation and Prediction of Flat and Molded Dash Panel Acoustic Performance and It’s Validation2019-26-01951/9/2019
In today’s automotive industry sound package material design and optimization is important considering the need for weight reduction and achieving targeted sound absorption and sound transmission loss values. As per traditional approach vehicle level noise reduction targets are defined considering flat samples, but in actual vehicle condition molded trimmed parts are used. This paper discusses about the systematic methodology developed for molded sample characterization in terms of BIOT’s properties. Effects of different parameters like area wise thickness variation, density variation on BIOT properties is studied. Comparison of BIOT’s properties of flat and molded dash sample is done to study the effect of molded structure. Using these BIOT’s properties prediction of sound absorption and sound transmission loss results carried out using FTMM approach for flat sample and SEA approach for molded sample. These predicted results validated with experimental sound absorption and sound transmission loss measured in reverberation chambers and in impedance tube. Finally, suggestions are given to account critical parameter like thickness variation affecting the BIOT’s properties and in turn acoustic performance of sound package material. It can help NVH engineers during actual design and development of sound package material.
Joshi, Manasi P.Jain, SachinkumarKamble, Jr., Prashant PrakashKaranth, Nagesh Voderahobli
Performance Evaluation of Two Wheeler Brake System Using Coupled Thermo-Mechanical Simulation2018-01-189610/5/2018
Safety aspect has been a key requirement in designing braking system. However, non-safety aspect like NVH and thermal performance are gaining equal importance. High engine capacity (cc) motorcycles are prone to thermal and NVH issues as braking energies are more. Therefore, virtual validation of brake disc system by considering both dynamic and thermal load with predefined assumptions is a toughest challenge when confronted with reality boundary conditions. Thus, the paper comes in a unique way of coupling dynamic and thermal load executed between multi body dynamics (MBD) and heat transfer equation which will convey results closer to real time scenario. MBD solves motion and the dynamic influence on heat transfer is calculated using “sliding boundary condition”. A series of repeated braking condition are performed on front brake disc of motorcycle. The results obtained from the analysis shows critical temperature rise. As a consequence, disc thickness variation (DTV) due to thermal expansion are aggregated when coupled with dynamic friction. DTV will prove to be critical in concerning NVH and durability issues of brake disc. Braking conditions are numerically simulated on finite element method (FEM) using nonlinear approach and results are summarized with test data.
Sukumaran, SurajKalani, DineshSuryavanshi, YogeshKokane, GirishDeshpande, MoreshKharul, Ravindra
Closures weatherstrips with variable cross sections2018-36-01529/3/2018
Closures systems performance is a trade-off between NVH (Noise, Vibration and Harshness) and DCE (Door Closing Efforts) requirements. Dynamic sealing performance and sheet metal rigidity are the key contributors for a stable system. The seals actuate like a spring on the system. Higher seal load is good for NVH performance, adding more dumping to the system, but it will negatively affect DCE, as it will demand additional energy to close the system. Nominal seal load must be defined to achieve a balance between these attributes. This study is about dynamic sealing profiles with variable seal load, which provides tunable solutions to address the trade-off between NVH and DCE on the side doors or rear closures. Dynamic sealing weatherstrips are made of sponge EPDM extruded profiles with a specified load, defined by its CLD (Compression Load Deflection), which is given by the cross section design. While standard extrusion process produces a single cross section profile, a new extrusion technology provides the possibility of varying the profile cross section along the extrusion, thus the possibility to have different CLDs along the length of door perimeter. This technology can assist on the issues that demand quick solutions on vibrations and load relieves, providing good results for these critical attributes. Timing and costs are very attractive as well on the small car segments.
Filho, Rineu SantamariaFromel, IngoOsti, Reinaldo
The Use of “Big Data” for the Analysis and Design of Vehicle Sound Packages2018-01-15706/13/2018
With the ever-decreasing timescales and increased performance requirements afforded to OEM’s, it has become essential that NVH suppliers provide optimum palliative solutions that comply with a vehicles acoustic targets. The acoustic effect of any palliative treatment attached to a vehicle body system depends on its ability to attenuate noise energy passing through or radiating from the system or its interaction with reflected sound from other areas. Acoustic performance uses targets relating to sound insertion loss (SIL) and / or sound absorption and these are identified to the component supplier by the OEM at the “request for quotation” (RFQ) stage. For many potential suppliers, especially those with a limited portfolio of material options, success or failure is quite straightforward. However, the problem occurs when the material and processing opportunities cover wide parameters and the available combinations and permutations are extensive. It is no longer a simple choice to get the best solution. Ultimately, competitiveness relies on the optimum choice of material types, combinations and processing along with associated cost and this requires a detailed understanding of the ‘physics’ involved. Whilst material prediction software is frequently used to spot check performance prior to actual material testing this technique cannot guarantee success. It is also very time consuming and requires considerable training. The aim of this project was to use “Big Data” to automate the selection process. This paper describes the Authors work with “Big Data” combined with associated algorithms, so that once a system target is received a range of suitable solutions can be offered without pre-determination of parameters. It covers the creation of the “Big Data” landscapes and the integration of the procedure into a web based easily accessible application.
Morris-Kirby, Rod
Development of New I3 1.0L Turbocharged DI Gasoline Engine2017-01-242410/8/2017
In recent years, more attentions have been paid to stringent legislations on fuel consumption and emissions. Turbocharged downsized gasoline direct injection (DI) engines are playing an increasing important role in OEM’s powertrain strategies and engine product portfolio. Dongfeng Motor (DFM) has developed a new 1.0 liter 3-cylinder Turbocharged gasoline DI (TGDI) engine (hereinafter referred to as C10TD) to meet the requirements of China 4th stage fuel consumption regulations and the China 6 emission standards. In this paper, the concept of the C10TD engine is explained to meet the powerful performance (torque 190Nm/1500-4500rpm and power 95kW/5500rpm), excellent part-load BSFC and NVH targets to ensure the drivers could enjoy the powerful output in quiet and comfortable environment without concerns about the fuel cost and pollution. The combustion system with side-mounted 6-hole direct injector and 200bar injection pressure has been optimized by CFD simulation and optical engine investigation. To ensure performance output and transient responsiveness, an efficient and low inertia turbocharger was selected. Effective technical measures including friction reducing, thermal management, variable oil pump and Dual VVT were applied in order to achieve the good fuel economy. Special attentions have been paid to the engine structure design, mass balancing strategy and mounting system optimization to achieve excellent NVH performance which is at same level similar to a 4-cylinder TGDI gasoline engine. Benefited from the modular design concept, the engine size was minimized, which has the advantage for packaging, especially for hybrid vehicles. Through the development work, the engine performance and BSFC targets have been achieved and confirmed by engine and vehicle tests. This engine has been installed in one of the passenger cars (1205 to 1320kg) and 18% fuel consumption reduction has been achieved in the NEDC cycle compared to 1.6L NA engine while maintaining fun-to-drive and NVH performance
Zhang, SheminLi, HuapingChen, TaoJiang, NanTan, XinzhenDeng, LimeiXia, QingsongKapus, PaulMa, MingtangLi, WeiZhang, JunqiangMa, QingjunXia, Yong
NVH Performance Improvement of a Turbo-Charged GDI Engine based on the Simulation and Experiment Studies2017-01-242610/8/2017
In recent years, Turbo-charged GDI technology is more and more widely used, which can meet the high demand of the engine performance and efficiency, but the resulting reliability and NVH issues also need to be paid attention to [1]. Traditional NVH performance improvement is mostly based on the experience design and repeatable test, which lead to longer development period, high cost, and also ineffective results. NVH performance simulations play more important role in engine vibration and noise prediction along with the development of the simulation technology[2][3]. The force response analysis is usually used to evaluate the NVH performance of the engine structure under the standard excitation. However, dynamic analysis of the crank train, valve train, and piston can be carried out based on the AVL software family, also the vibration and airborne noise of whole engine can be predicted directly at different speed and load [4]. The NVH performance of a turbo-charged GDI engine was studied based on the simulation and experiment in this paper. Firstly the engine NVH targets including the airborne noise, mount vibration and so on are set up, and the targets are broken down into system and component if possible. Secondly, the mechanism dynamics, engine vibration and noise simulations were carried out, and the weaknesses of the original engine design had been found out. Some appropriate structural improvements to the main parts and new NVH performance prediction were done according to the targets of NVH performance. Then experiment results show that simulation method of radiation noise OA level prediction is basically correct, and a series of structural improvement measures are very effective. Some special problems such as the turbocharger noise were also investigated, and some remarkable effects have been achieved.
Zhang, ZhimingWang, WeiminWang, JiangtaoZhang, JimingChen, YuandaZhang, WenlongYang, GuofangFan, FuguiZhang, WenxiangHuang, FengqinLi, Xiangwang
Optimization of Bushing Stiffness Using Numerical Approximation Model to Improve Automotive NVH Performance2017-01-18046/5/2017
An efficient method to determine optimal bushing stiffness for improving noise and vibration of passenger cars is developed. In general, a passenger vehicle includes various bushings to connect body and chassis systems. These bushings control forces transferred between the systems. Noise and vibration of a vehicle are mainly caused by the forces from powertrain (engine and transmission) and road excitation. If bushings transfer less force to the body, levels of noise and vibration will be decreased. In order to manage the forces, bushing stiffness plays an important role. Therefore, it is required to properly design bushing stiffness when developing passenger vehicles. In the development process of a vehicle, bushing stiffness is decided in the early stage (before the test of an actual vehicle) and it is not validated until the test is performed. If it turns out that vehicle performances are not satisfied in the test, another test with bushing changed needs to be conducted, which requires additional costs. Several tests are usually performed to identify bushings which achieve target performances. In addition, the decision of bushing stiffness is complicated since there is typically a conflict between requirements for bushing stiffness from various vehicle performances, such as ride, handling, noise, and vibration. Therefore, in the design stage, the validation of bushing stiffness is desirable to save costs of the vehicle development and ensure the performances of the vehicle. In this paper, a novel optimization methodology based on a numerical approximation model is presented. This method is used to determine optimal stiffness values of bushings in a vehicle for improving the vehicle noise. By using the method, it is found that bushing stiffness is well optimized while reducing the noise.
Jung, ChulwooKim, Hyeon SeokOh, HyuckjinHwang, Kwang HyeonPark, Hun
A 1-D Simulation Model for Analysis and Optimization of Gearbox Rattle Noise2017-01-17806/5/2017
In the design or match process of vehicle powertrain system, gearbox rattle is a common NVH problem which directly affects passengers’ judgment on the quality and performance of vehicle. During the development process of a passenger car, prototype vehicles have serious gear rattle problem. In order to efficiently and fundamentally control this problem, this work first studied the characteristics and mechanisms of the gearbox rattle. The study results revealed that the torsional vibration of powertrain system was the root cause of gearbox rattle. Then a simulation model of the full vehicle was built with the aid of Simulink® toolbox, which is a graphical extension to MATLAB® for modeling and simulation of variety of systems. With this model, the sensitivity analysis and parametrical optimization were performed, and the simulation results indicated that the dual-mass flywheel (DMF) was the best measure to control the rattle. In order to verify this conclusion, this work developed a DMF system and embedded it into the powertrain of the prototype vehicle. Both subjective evaluation and the objective measurement on the vehicle indicated that the gearbox rattle problem was successfully solved. The main significance of this study is to establish an effective and easy approach to analyze and control the gearbox rattle. The indicative conclusions of this work could be referred by NVH engineers in the early phase of vehicle development.
Xu, Yong
Enhancing Transmission NVH Performance through Powertrain Control Integration with Active Braking System2017-01-17786/5/2017
This paper explores the potentiality of reducing noise and vibration of a vehicle transmission thanks to powertrain control integration with active braking. Due to external disturbances, coming from the driver, e.g. during tip-in / tip-out maneuvers, or from the road, e.g. crossing a speed bump or driving on a rough road, the torsional backlashes between transmission rotating components (gears, synchronizers, splines, CV joints), may lead to NVH issues known as clonk. This study initially focuses on the positive effect on transmission NVH performance of a concurrent application of a braking torque at the driving wheels and of an engine torque increase during these maneuvers; then a powertrain/brake integrated control strategy is proposed. The braking system is activated in advance with respect to the perturbation and it is deactivated immediately after to minimize losses. The powertrain control compensates for the added resistance and reestablishes the vehicle longitudinal performance according to driver’s commands. The torsional preload created in the driveline is effective in preventing/reducing vibrations and associated noise. It is worth underlining that the proposed methodology can be directly applied to existing ABS/ESC units, composed of digital solenoid valves, and does not require additional hardware components. The effectiveness of this method has been experimentally validated by means of a Hardware In the Loop (HIL) test bench which includes a Dual Clutch (DCT) transmission and a hydraulic brake system with a customized ABS/ESC unit.
Galvagno, EnricoTota, AntonioVelardocchia, MauroVigliani, Alessandro
Assessment of Lightweight Automotive Glass Solutions on Interior Noise Levels & Sound Quality2017-01-18146/5/2017
The automotive industry continues to develop technologies for reducing vehicle fuel consumption. Specifically, vehicle lightweighting is expected to be a key enabler for achieving fleet CO2 reduction targets for 2025 and beyond. Hybrid glass laminates that incorporate fusion draw and ion exchange innovations are thinner and thereby, offer more than 30% weight reduction compared to conventional automotive laminates. These lightweight hybrid laminates provide additional benefits, including improved toughness and superior optics. However, glazing weight reduction leads to an increase in transmission of sound through the laminates for certain frequencies. This paper documents a study that uses a systematic test-based approach to understand the sensitivity of interior vehicle noise behavior to changes in acoustic attenuation driven by installation of lightweight glass. Specifically, this study evaluates the influence of a lightweight windshield on wind, road, and powertrain contributions to vehicle interior noise. To facilitate this assessment, operating tests were conducted utilizing variable operating conditions and road surfaces such that varying balances of powertrain, wind, and road-induced interior vehicle noise could be evaluated. A time-domain noise transfer path analysis (TPA) was conducted, including multiple sources to quantify the contributions of powertrain, wind, and tire-induced noise. Prototype glass treatments were installed, and differences in measured airborne noise transfer functions were used to update the TPA model for interior noise prediction. To eliminate the influence of test reproducibility, a consistent set of “source” data was used throughout this study. Based on the results of the iterative TPA analysis, the influence of glass acoustic performance on interior sound was assessed. The use of a time-domain TPA process facilitated both subjective and objective assessment of interior sound quality. Based on the results from this analysis, minimal degradation was observed in vehicle-level NVH performance using the hybrid laminate comprising of lightweight glass, relative to conventional laminate and the lightweight glass was assessed to be a viable enabler for the vehicle application considered.
Tousignant, ToddGovindswamy, KiranBhatia, VikramPolasani, ShivaniFisher, W Keith
Enhancement of Damping Performance of CLD Treatment Using Segmentation Method2017-01-18826/5/2017
The reduction of vibration and noise is a major requirement for performance of any vibratory system. Due to legislative pressures in terms of external pass by noise limit of vehicles and customer requirements for better noise and ride comfort in vehicle, NVH attribute has become an important parameter. Major sources for vehicle pass-by noise consist of powertrain, tire and wind. Damping treatment is important to reduce vibration and noise radiation. The passive constrained layer dampening (CLD) treatment can be used to reduce structure-borne noise of vibrating structure using viscoelastic damping material. The performance of the passive constrained layer damping treatment can further be enhanced by new segmentation technique. The concept of segmented CLD is based on edge effect. The efficiency of segmenting a constrained layer damping treatment relies on the fact that a high shear region is created in the viscoelastic layer. The shear deformation in the viscoelastic material is not significant in regions where the bending moment is maximal. Segmenting induces shear in the damping layer and thereby increases damping ability. A cut in the damping treatment gives an additional shear deformation at that position. Hence a cut has to be located at the maximum displacement. The position of maximum displacement for all the first four bending modes is identified by bending mode shape. The bending mode shapes are obtained by MATLAB program. The damping performance is further increase by using multiple cuts in CLD beam. The optimized positions of multiple cuts are obtained by Genetic Algorithm (GA) optimization technique. The damping performance of CLD beam is measured in terms of vibration response (dB) and composite loss factor (η).This paper focused on comparison of damping performance of full CLD treatment and segmented CLD treatment. The experimental investigation is performed by using Accelerometer, Impact hammer and FFT analyser ( B&K make ). The new innovative segmented CLD treatment is found to be very much effective.
Hujare, Pravin P.Sahasrabudhe, Anil D.
Optimization of Local Stiffness for Reducing Off-Highway Machinery Interior Noise2017-01-18396/5/2017
It is common for automotive manufacturers and off-highway machinery manufacturers to gain insight into the system’s structural dynamics by evaluating the system inertance functions near the mount locations. The acoustic response of the operator’s ears is a function of the vibro-acoustic characteristics of the system structural dynamics interacting with the cavity, with the actual load applied at the mount locations. The overall vibro-acoustic characteristics can be influenced by a change in local stiffness. To analyze the response of a system, it is necessary to go beyond analyzing its transfer functions. The actual load needs to be understood and applied to the transfer function set. Finite element (FE) based analysis provides a good foundation for deterministic solutions. However the finite element method decreases in accuracy as frequency increases. Many NVH problems happen to be at the mid frequency range where solving the problem with the FE-only approach falls short [1]. This project utilizes the high definition nature of test-based frequency response function for the main structure, the flexibility of FE-based FRF synthesis for the body attachments, in conjunction with the inverse force estimation technique to address a fluid-borne noise problem in the mid frequency range. Various design options of body attachment are to be evaluated numerically to reduce interior noise at the operator’s ears.
Lee, Edward T.
Interior Noise and Vibration Reduction of BRT - Premium Segment Bus2017-01-18666/5/2017
Urbanisation has led to an increased need for mobility in public transportation. Sensing the unfolding worrisome scenario, many countries have taken up different mass rapid transit solutions to alleviate the problem and restore the free flowing traffic. BRT should have been the logical choice particularly considering the lower capital costs involved and faster implementation. Comprehensibly the expectations of this class of vehicles will be high in term of quality and comfort to the passengers. Level of vibration and noise is an important indicator to evaluate vehicle's ride comfort. The challenges are to design the high powered Powertrain and Air Conditioning system nonetheless low interior noise, vibration and harshness correspondents to personal cars. This paper is an invention of, development work done in interior noise refinement of a bus. A prototype bus manufactured to meet all the requirement of BRT - premium segment urban bus. The prototype was almost meeting the entire required specifications, excluding interior noise and vibrations. The rear zone of the interior was the major concern of NVH levels, which demands to carry out the root cause analysis. There were various structure-borne and air-borne sources contributing to increase in NVH levels. Design and development iterations were conducted on the vehicle to achieve the well significant noise and vibration reduction and increased comfort to the passengers.
Jawale, PradeepKaranth, Nagesh
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