Browse Topic: Interior noise

Items (461)
Find
Blade Stiffened Carbon/Epoxy Panels with Longitudinally Tapered Acoustic Black Holes for Vibration ReductionF-0081-2025-02765/20/2025
Carbon/epoxy stiffened panels are being increasingly used in transport rotorcraft. The reduced mass density and high stiffness of carbon/epoxy composites can lead to higher levels of vibration relative to comparable metallic structures, which themselves can have vibrations and interior noise high enough to damage the hearing of crew and passengers. The current investigation explores a method to reduce the vibration of carbon/epoxy stiffened panels by introducing thickness tapers known as acoustic black holes (ABHs). The ABH feature is integrated into either the stiffeners or plate of a representative stiffened panel configuration. A finite element (FE) parametric study was used to guide designs that reduce the vibration of the panel without compromising the compressive buckling capability or mass of the panel. FE studies showed that a 30 ply to 12 ply thickness taper longitudinally oriented in the blade stiffener can reduce vibrations and increase compressive buckling capability. Carbon/epoxy panels were manufactured using a low-cost out-of-autoclave material with simple molding. Experimental testing concluded that integrating the ABH into the stiffeners longitudinally helped to reduce the broadband vibration by 5 dB and increase the buckling load (+4.3%) and collapse load (+16.5%) without increasing the mass greatly compared to a traditional baseline design.
Brown, Avery, Patel, Bhavya, Robertson, Noah, Bakis, Charles, Smith, Edward, Beck, Ben, Shepherd, Micah, Vlajic, Nicholas
Circular Acoustic Black Holes Integrated into Carbon/Epoxy Stiffened Panels for Noise ControlF-0080-2024-12455/7/2024
Carbon fiber reinforced epoxy composite stiffened panels are increasingly being used for structural components in large transport rotorcraft. However, problems are arising with high levels of vibration and interior noise due to the increased stiffness-to-density ratio of composites. The current investigation explores the potential of reducing vibrations in carbon/epoxy stiffened panels with the integration of acoustic black holes (ABH), namely features that incorporate a power law thickness taper. The proposed approach involves designing a taper into the thickness of the blade stiffeners as well as the thin plate. Integration of ABHs into the fuselage structure has the potential to reduce broadband vibrations. Multiple parametric studies with either an ABH integrated into the blade stiffener or a grid of ABHs integrated into the plate were conducted, and the tradeoffs between vibration amplitudes, panel mass, and compressive buckling load were examined. Carbon/epoxy panels were fabricated using vacuum-bag-oven processing with out-of-autoclave prepreg and verified to be of good quality. The integrated velocity response, a proxy for the radiated noise from a panel, and compressive buckling were simulated using finite elements. Comparisons were made to experimentally measured data from modal testing and compression buckling testing. Experimental results indicated that when an ABH is integrated into the blade stiffener and 15 ABHs are integrated into the plate in a grid configuration, the panel mass was unchanged, the integrated velocity response decreased by 2.82 dB, and the buckling load increased by 2.9% compared to a baseline non-tapered design.
Brown, Avery, Vlajic, Nicholas, Shepherd, Micah, Beck, Ben, Smith, Edward, Bakis, Charles, Robertson, Noah, Patel, Bhavya
Road Noise Evaluation by Sound Quality Simulation Module2020-01-12754/14/2020
An objective evaluation of sound quality is a technical bridge connecting sound pressure level (SPL) and human auditory sensation. In this paper, an algorithm is proposed for calculating objective evaluation parameters of sound quality (including loudness, sharpness and articulation index), considering acoustic characteristics of human external ear, middle ear and inner ear to reflect auditory sensation. A sound quality simulation (SQS) module is coded according to the algorithm. The module is used for evaluating sound quality of road noise from an SUV in three steps. Firstly, interior noise is predicted by integrating finite-element method (FEM), hybrid FE-SEA method, and statistical energy analysis (SEA) for low frequency (20~315 Hz), medium frequency (315~500 Hz), and high frequency (>500 Hz) in 1/3 octave band, respectively. The predicted interior noise SPLs are compared with the measured results, with deviations less than 3dB in average. Secondly, the sound quality parameters are calculated using the predicted SPLs in the SQS module. The predicted and measured loudness, sharpness, and articulation index are compared, with average deviations less than 5%. Finally, the predicted interior noise is filtered by the SQS module in 1/3 octave band, to determine the dominant contribution bands for the sound quality parameters. Several optimized designs are implemented to optimize the sound quality parameters, and validated by experiments.
Gu, Perry, Mao, Jie, Chen, Zhidong, Ding, Zhi, Cheng, Lei, Zhu, Zhenying, Peng, Hong
The Resolution of 8th Order Whining Noise for a Battery Electric Vehicle2020-01-12694/14/2020
With significant improvement in overall vehicle NVH performance in recent years, sound quality has increasingly become an important customer concern. In search of excellence in customer satisfaction with BEVs (Battery Electric Vehicles), optimizing e-motor noise is one of the most effective ways to improve the vehicle sound quality. This paper aims to resolve a whining noise issue from a PMSM (Permanent Magnet Synchronous Motor) during the development of a BEV program. The most critical order of the whining noise from an e-motor on market today is most likely the 48th order, which could be mitigated by implementing sound package material on the motor casing. In this work, however, the 8th order instead is found to be the most critical issue, and it is perceived as the whining noise in the frequency range under 600Hz. With such a low frequency content, sound package treatment has little effect. With subjective evaluation and test data analysis, it is found that the worst case is associated with the peak of the 8th order. The 8th order electromagnetic force is induced by eccentricity, and as a consequence the inverter housing is excited and thus radiates noise, which makes a significant contribution to the overall motor whining noise level. Meanwhile, with inadequate design of the bearing system architecture and insufficient stiffness to support it, the combined rotor and gear system structure vibrates at specific frequencies. These vibrations further amplify the whining noise, which renders the emitted noise particularly annoying. Based on the principals of structural dynamics, the most effective way to alleviate the issue is to avoid or reduce the resonance of the rotor and gear system. However, this countermeasure is related to involved engineering details which are restrained by cost and timing as well as the supplier capabilities. In this work, it is proposed to resolve the issue by increasing the inverter housing stiffness and implementing a piece of damping material. After carrying out the proposed design improvements, it is shown that the whining noise level has been reduced significantly with a 5dB(A) reduction in overall motor noise level. Finally, the vehicle performance is rated acceptable by subjective evaluations.
Feng, Jingting, Deng, Jianjiao, Liu, Yingjie, Hou, Hangsheng, Oka, Ryusuke
Vibrational Analysis Method on High-frequency Electric-drive Motor Noise2020-01-04634/14/2020
When a vehicle is cruising, unpleasant noise in the 4 to 5 KHz high-frequency band can be heard at the center of all seats in the vehicle cabin. In order to specify the source of this noise, the correlation between the noise and airborne noise from the outer surface of the transmission was determined, and transfer path analysis was conducted for the interior of the transmission. The results indicated that the source of the noise was the 0th-order breathing mode specific to the drive motor. To make it possible to predict this at the desk, a vibrational analysis method was proposed for drive motors made up of laminated electrical steel sheets and segment-type coils. Material properties data for the electrical steel sheets and coils was employed in the drive motor vibrational analysis model without change. The shapes of the laminated electrical steel sheets and coils were also accurately modeled. The status of minute slippage between the laminated layers and contact between the electrical steel sheets and the coils were also considered in the model. First, the results of an eigenvalue analysis of the laminated electrical steel sheets in isolation were compared with those of an experimental modal analysis. Natural frequencies and eigenmodes matched with a deviation of within 2% up to 6 kHz. Next, a vibrational analysis of an electric drive motor model featuring coils press-fit into the laminated electrical steel sheets was conducted. In order to enable accurate reproduction of twisting stiffness and bending stiffness in the coil model, which featured a rectangular cross-section, equivalent material properties were defined for the finite element model. In addition, penalty contact stiffness was defined for the laminated steel sheets and coils. Comparison of the results of an analysis conducted using the drive motor model with the results of an experimental modal analysis using an electromagnetic shaker showed that the phenomenon of natural frequency peaks exceeding 2 kHz becoming unclear was captured by the simulation. In addition, the eigenmodes up to 5 kHz, in particular the fact that there is a 0th-order breathing mode at 4.2 kHz, were accurately reproduced.
Saito, Toshihiro, Miyamoto, Koji
Applications of Strain Measurements to Improve Results on Transfer Path Analysis2019-36-03231/13/2020
Vehicles with lower noise levels and better levels of vibratory comfort for passengers made the area of noise, vibration and harshness (NVH) one of the main areas related to the perception of vehicle quality. Several approaches on the contribution of transfer paths have been studied to define the propagation energy in vehicular structures. Transfer Path Analysis (TPA) is a tool to improve NVH performance with the primary goal of reducing and improving perceived vibrations and noise in the cabin vehicle by occupants. Indirect methods are especially important in cases where the force signals are immeasurable in practice in terms of cost and space for sensor couplings, in the measurement configuration, and particularly in the case of distributed forces. The matrix inversion method, perhaps the most popular classic TPA, identifies operational forces using passive body acceleration. However, removal of the source can change the dynamic characteristics of the assembled structure and increase the time of the experiment, which results in misleading information in the measurements. For this reason, the inversion operation of the acceleration matrix can give erroneous results, where the condition number of the inverted matrix gains considerably high values, especially in the resonant frequencies. Thus, this paper proposes the comparative study of force estimation techniques and transfer paths, based on the matrix inversion method with and without the application of strain techniques and compares with the computational model of the system. In order to carry out this work, an academic test bench simulating a vehicular powertrain was used. The results showed a good compromise between forces and transfer paths and a significant improvement in some frequencies using sensor fusion techniques.
Ramos, A. C. R., Melo, C. A. P., Álvarez-Briceño, R., de Oliveira, L.P.R
Technique for Front-loading Countermeasures against Deterioration of Sound Quality in Vehicle Interior due to Rapid Combustion in an SI Engine2019-01-230412/19/2019
This paper discusses a technique for the examination of countermeasures at the design stage of the prototype vehicle in order to realize efficient enhancement of the engine combustion noise quality in the vehicle interior. An existing sound quality evaluation method was applied as a simulation technology. The deterioration of the sound quality of combustion noise in the passenger compartment of a new vehicle was estimated from the in-cylinder pressures of a newly developed engine measured on a dynamometer test bench and the structural response functions obtained from the previous mass production vehicle. In addition, the level of reduction in structural response sensitivity necessary for the enhancement of combustion noise quality was estimated for each frequency band. Based on the results, effective countermeasures for the enhancement of combustion noise quality were selected and reflected in the drawings for the initial prototype vehicle. This made it possible to realize the target combustion noise quality in the initial prototype vehicle, which in turn eliminated the necessity for the additional combustion noise countermeasures that have often been applied at the later stages of conventional vehicle development.
Torii, Kenji, Tsuruta, Tatsunori
GKN spreads premium propshaft tech to quiet pickup cabins19AUTP10_1110/1/2019
It may seem a long way in engineering and NVH terms from premium European cars such as Audi's A5 and A7 to light duty trucks, but GKN Automotive has bridged that gap with its latest lightweight all-wheel drive (AWD) modular propshaft. Many pickups suffer a significant amount of unwanted NVH emanating from the front propshaft, with its two universal or CV joints and an interconnecting shaft positioned below and close to the passenger cabin. But now GKN Automotive has “re-characterized” its premium car driveline system to an entirely different vehicle category. “With a traditional truck front propshaft, the level of noise entering the cabin is perceived as a drone,” explained Michael Miller, GKN's propshaft product technology manager. “We've worked on applications of our new technology where the cabin NVH levels have been dramatically reduced. Positive results stem from the combination of joints used in our lightweight modular front propshaft.”
Birch, Stuart
Application of Multi-Attribute Weighted Gray Target Decision in Automobile Noise Reduction Scheme Evaluation02-12-03-00147/3/2019
In the selection of automobile noise reduction schemes, the lack of comprehensive quantitative index system and objective evaluation method is a serious problem. In this article, the methods of analytic hierarchy process (AHP) and gray target decision were used to solve the problem. Firstly, AHP and gray target decision method were introduced respectively in detail. Secondly, three automobile noise reduction schemes were illustrated. Four types of data were selected as the decision indexes, and the weight coefficients of all the decision indexes were calculated using the AHP. Then multi-attribute mixed weighted gray target decision model was established. The optimum scheme was obtained by the calculation of the off-target distance and the sorting of the calculation results. The proposed method can quantify the evaluation process and overcome the disadvantages of the traditional analogy method. The example shows that the method is feasible.
Zhao, Zhendong
Determination of Vehicle Interior Noise due to Electric Motor2019-01-14576/5/2019
This paper introduces an approach that uses a statistical energy analysis (SEA) method for prediction of noise in the vehicle cabin from an electric motor sound source placed in the engine compartment. The study integrates three different physics, namely, electromagnetics, harmonics, and acoustics. A 2004 Prius permanent magnet synchronous motor with an interior permanent magnet was used for performing the integrated CAE analysis, as the motor’s design details were readily available. The Maxwell forces on the stator teeth were first calculated by an electromagnetic software package. These forces were then mapped into a finite element model of the motor stator to predict the velocity profiles on the stator frame. Velocity profiles were considered as boundary conditions to calculate sound pressure levels and the equivalent radiated sound power level in the acoustic environment. The calculated sound power was used as an input sound source to perform SEA simulation to determine sound pressure level at the driver’s right ear in the passenger compartment. A sensitivity analysis of the motor design was performed on the sound power level generation and the sound noise level at the driver’s right ear in the passenger component. It was found that the air gap of the motor created significant effects on the radiated sound power.
Joshi, Sanket, Cherng, John G., Salvekar, Pinak, Raveendra, Ravi
Tonal Annoyance Metric Development for Automotive Electric Vehicles2019-01-14676/5/2019
Historical metrics intended to drive the development of vehicle powertrains have focused on sounds that are characteristic of IC engines. The interior noise contribution of the propulsion system in electric vehicles has significantly more tonal noise (and much less impulsive and broadband noise) than their IC engine counterparts. This tonal noise is not adequately represented by current propulsion systems metrics. While metrics exist today that were developed to represent the presence of tones in sounds most have focused on the level aspect of the tones relative to the surrounding noise or masking level, some examples include tonality, tone-to-noise ratio, and prominence ratio. A secondary, but also important aspect of tones is the annoyance as a function of frequency. This paper will highlight the development of a tonal annoyance weighting curve that can be used to account for the frequency aspect of tonal annoyance relative to electric vehicles. This weighting curve can then be used in conjunction with the current tonal metrics to represent perceived tonal annoyance of electric vehicles. The benefit of the tonal annoyance weighting curve is demonstrated by comparing the correlation of a common commercially available tonality metric before and after the weighting curve was applied to a subjective study of 8 electric vehicle sounds with significantly different frequency content.
Pietila, Glenn, Seldon, William, Roggenkamp, Timothy, Bohn, Timothy
Subband Adaptive Filtering Algorithms for Active Broadband Noise Control in Impulsive Vehicle Noise Environment2019-01-15286/5/2019
Subband adaptive filtering (SAF) techniques have been increasingly used in active noise control (ANC), especially for acoustic broadband noise signal and system models with long impulse responses. In ANC, the closed-loop delayless SAF schemes improve the convergence rate of the widely adopted conventional filtered-x LMS (FxLMS) algorithm in a more computationally efficient manner under wideband noises like colored signals or even nonstationary signals. In most real-world environment like vehicle interior cabin, however, the performance of ANC can be degraded by various outliers, including non-Gaussian impulsive signal such as transient impact acoustic response for road noise. Although several robust objective error criteria as well as threshold based LMS-type adaptive filtering algorithms have been investigated for active impulsive noise control, the computational burden would be challenging for implementation and the requirement of a priori knowledge of noises cannot be fulfilled in many cases. In this paper, various state-of-the-art SAF algorithms with decorrelating property are studied in terms of the convergence property for broadband noise control in impulsive environment since the subband decomposition might alleviate the sudden change of adaptive systems by spreading energy to multiple channels. The SAF algorithms with low-order norm of error evaluation and variable step sizes are further evaluated via simulations for the input of symmetric α-stable (SαS) impulsive noise and colored noise in the impulsive environment, respectively. Results show that the delayless SAF algorithms appear more robust than the conventional LMS-type algorithms for impulsive noises. Moreover, the utilization of band-dependent variable step sizes for the delayless SAF algorithms significantly improves the convergence rate.
Long, Guo, Wang, Kan, Lim, Teik
Performance Testing and Analysis of Multi-Channel Active Control System for Vehicle Interior Noise Using Adaptive Notch Filter2019-01-15676/5/2019
It is considered that slow convergence speed and large calculation amount of commonly used adaptive algorithm in the active control system for vehicle interior noise yield noise reduction performance and hardware requirements problems. In this paper, a 4-channel active control of vehicle interior noise based on adaptive notch filter is established, and road test is carried out to test and analyze the performance of the control system. Firstly, the general mathematic model of the multi-channel active control system based on adaptive notch filter is established. The computational complexity of the algorithm is analyzed and compared with that of the FXLMS algorithm. Secondly, a hardware-in-the-loop test bench based on multi-channel adaptive notch filter is set up, to measure the noise reduction performance of ANC system under various working conditions. Finally, the typical test conditions are designed to test the system noise reduction performance, and the road test is carried out and result is analyzed.
Zhang, Lijun, Zhang, Xiyu, Meng, Dejian
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, Ying, Shi, Zhenghong, Folts, Christopher, Kopp, Gregory, Sun, Zhaohui, Sandstrom, 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, Vinod, Parbat, Aniket, Charan, Anil
Wind Noise Transmission Loss for Separated Flow Conditions2019-01-14696/5/2019
The transmission of turbulent flow pressures through panels to the interior noise depends on the spatial matching of the pressure and vibration fields. Since the exterior pressure field on a moving vehicle includes both turbulent pressure and acoustic pressure, both need to be factored into a noise transmission loss calculation. However, these two exterior pressure fields have very different spatial patterns. This is further complicated when the exterior flow is separated from the surface due to an obstruction. This study uses wind tunnel and road tests to measure and model the wind noise transmission loss through the side glass of a vehicle. The results are seen to be very different from the traditional sound transmission loss curves for an acoustic pressure source.
DeJong, Richard, Sorenson, Steve
Assessment of Automotive Environmental Noise on Mobile Phone Hands-Free Call Quality2019-01-15976/5/2019
Environmental noises such as wind, road, powertrain, and HVAC noise are important aspects to consider when implementing a hands-free terminal for mobile phone calling from within a car. Traditionally, these environmental noises have been exclusively considered for driver comfort; however, with the introduction of the hands-free terminals (HFT) and increasing consumer demand relative to mobile phone call quality, a broader implication of high background noise levels should be considered. HFT algorithm development and implementation can and does provide a high level of background noise suppression to mitigate these concerns, but this is often done at the expense of computational power and cumulative delay during a phone call. The more advantageous solution would be to address the problem from a source and path perspective with emphasis on reduction of noise in the frequency bands which most influence call quality performance. The assessments shown throughout this paper establish a sensitivity of HFT call quality to background noise levels based on industry-standard metrics, including those defined by International Telecommunication Union (ITU) standards. These assessments were established based on a series of experiments that include characterizing vehicle to vehicle variability with a common background noise and single vehicle sensitivity to reductions in background noise. In the background noise sensitivity investigations, filtering investigations were conducted to identify the frequency ranges which drive the most significant degradation in speech intelligibility and HFT performance. The information gained provides insight regarding the requirements for mitigating background noise in the context of both customer comfort as well as HFT performance, both of which are key factors in the perception of overall vehicle quality.
Pruetz, Jeffrey, Watson, Channing, Tousignant, Todd, Govindswamy, Kiran
Evaluation of Uncertainties in Classical and Component (Blocked Force) Transfer Path Analysis (TPA)2019-01-15446/5/2019
Transfer path analysis (TPA) has become a widely used diagnostic technique in the automotive and other sectors. In classic TPA, a two-stage measurement is conducted including operational and frequency response function (FRF) phases from which the contribution of various excitations to a target quantity, typically cabin sound pressure, are determined. Blocked force TPA (also called in situ Source Path Contribution Analysis, in-situ TPA and component TPA) is a development of the classic TPA approach and has been attracting considerable recent attention. Blocked force TPA is based on very similar two stage measurements to classic TPA but has two major advantages: there is no need to dismantle the vehicle and the blocked forces obtained are an independent property of the source component and are therefore transferrable to different assemblies. However, despite the now widespread reliance on classic TPA, and the increasing use of blocked force TPA in the automotive sector, it is rare to see any evaluation of the associated uncertainties. This paper therefore aims to summarize recent work and provide a guide to the evaluation of uncertainties in both forms of TPA. The various types of uncertainty are first categorized as, ‘model’, ‘source’ and ‘experimental’ uncertainties. Model uncertainties arise due to incomplete or inconsistent representation of the physical assembly by the measurements. Criteria are provided for evaluation of completeness in terms of measured quantities. Experimental and source uncertainties are evaluated through a first order propagation approach. Expressions are provided allowing the uncertainty in the target quantity to be estimated from measured quantities. Additional data storage and analysis is required but no additional measurements are needed over and above the usual TPA measurements. An illustrative example is provided.
Moorhouse, Andy, Meggitt, Joshua, Elliott, Andrew
A Comparison of Two Source Characterisation Techniques Proposed for Standardisation2019-01-15406/5/2019
Automotive industry shows an increased tendency towards characterisation of vibration sources by independent quantities such as blocked forces and free velocities. Currently two independent ISO working groups propose standards for this source characterisation process. Both standards are still under development. In this paper it is shown how the different approaches can be derived and compared using the general framework for Transfer Path Analysis (TPA). It is shown how one standard clearly relates to classical TPA methods (using interface forces), while the other standard adheres the component-based TPA principles (using blocked forces). Practical guidelines found in the standard proposals are reviewed, allowing for a qualitative comparison of the proposed procedures. To address typical problems regarding completeness of the interface, an addition is proposed that incorporates the use of 6-DoF Virtual Point forces and moments. It is shown how this approach can be applied to any force characterisation, improving the general usefulness of the found forces. A simulated numerical test case shows the procedure of both standards and discusses the added value of including rotational moments in the source-describing force vectors. An industrial application case demonstrates the application of the second standard with the addition of virtual point forces and moments, leading to perfect agreement with the on-board validation sensor.
van den Bosch, Daniël, van der Seijs, Maarten, de Klerk, Dennis
A Computational Process to Effectively Design Seals for Improved Wind Noise Performance2019-01-14726/5/2019
The ability to assess noise transmitted through seals to cabin interiors early in the design process is very important for automotive manufacturers. When a seal design is inadequate, the noise transmitted can dominate the interior noise, making the wind noise performance of the vehicle unacceptable. This can cause launch delays, increasing costs and risking loss of sales. Designing seals using conventional experimental processes is challenging, since the location and strength of flow noise sources are not known when the seal design is planned. Making changes to the seal system after the tooling stage is expensive for manufacturers as tooling and redesign costs can be considerable. Deliberate overdesign by adding multiple layers of seals in a wide range of locations also can reduce profit by unnecessarily raising part and manufacturing costs. Consequently, there is a strong motivation to use reliable computational capabilities to predict interior noise transmitted through seals early in the design process to address these challenges, designing seals right first time. The current study presents a computational process that can be used to predict interior noise transmitted through seals early in the design process. This computational approach uses a Lattice Boltzmann method (LBM) based computational fluid dynamics (CFD) solver to predict the transient flow field and exterior noise sources. A statistical energy analysis (SEA) solver was used to transmit noise from these sources into the cabin through glass panels and seals. Experiments were performed to quantify noise transmitted through glass panels, window seals and door seals, allowing validation of the computational predictions. Detailed flow analysis was performed to gain insight into the noise sources and the exterior loads on both the seals and glass panels. Accurate prediction of the seal noise and the insight provided by the flow analysis showed that this computational process can be used early in the vehicle development process to design efficient seals for improved wind noise performance.
Oettle, Nicholas, Powell, Robert, Senthooran, Sivapalan, Moron, Philippe
Effects of the Feature Extraction from Road Surface Image for Road Induced Noise Prediction Using Artificial Intelligence2019-01-15656/5/2019
Next generation vehicles driven by motor such as electric vehicles and fuel cell vehicles have no engine noise. Therefore the balance of interior noise is different from the vehicles driven by conventional combustion engine. In particular, road induced noise tends to be conspicuous in the low to middle vehicle speed range, therefore, technological development to reduce it is important task. The purpose of this research is to predict the road induced noise from the signals of sensors adopted for automatic driving for utilizing the prediction result as a reference signal to reduce road induced noise by active noise control (ANC). Using the monocular camera which is one of the simplest image sensors, the road induced noise is predicted from the road surface image ahead of the vehicle by machine learning. The effects to extract features (Histograms of Oriented Gradients (HOG) feature, autoencoder feature, Convolutional Neural Network (CNN) feature) from road surface images are evaluated by visualization result of t-SNE. From the features acquired by the above method, the frequency characteristics of the road induced noise are predicted using deep learning, which is generally considered to be high prediction accuracy as a machine learning method. For the eight kinds of road surface, we compared the road induced noise measured by the actual vehicle and predicted by using deep learning. The prediction result using extracted features of road surface image is more accurate than that using RGB value of road surface directly. This tendency accorded with a visualization result by t-distributed Stochastic Neighbor Embedding (t-SNE).
Nakamura, Shunsuke, Komada, Masashi, Matsumura, Yuichi, Matsushita, Kojiro, Ishizaki, Keisuke
Calculation Process with Lattice Boltzmann and Finite Element Methods to Choose the Best Exterior Design for Wind Noise2019-01-14716/5/2019
Wind noise in automobile is becoming more and more important as the customer expectations increase. On the other hand, great progress has been made on engine and road noises, especially for electric and hybrid vehicles. Thus, the wind noise is now by far the major acoustic source during road and motorway driving. As for other noises, automobile manufacturers must be able, for a new car project, to specify, calculate and measure each step of the acoustic cascading: Source Transfers, both solid and air borne In the case of the automotive wind noise, the excitation source is the dynamic pressure on the vehicle’s panels. This part of the cascading is the one influenced by the exterior design. Even if many others components (panels, seals, cabin trims) have a big influence, the exterior design is a major issue for the wind noise. The wind noise level in the cabin may change significantly with only a small modification of the exterior design. This paper addresses the problem of doing the good choice of exterior design in the early phases of a new vehicle’ project, to reduce the wind noise. First, it reminds the industrial context for an automotive car manufacturer and the phenomenon existing in the coupling between a turbulent flow and a vehicle’s panel. Then it presents a new numerical process based on the dynamic coupling of two models: Calculation of the flow and pressure around the vehicle with a solver based on the Lattice Boltzmann Method Vibration and acoustic radiated by the lateral window with a finite element model The advantages, disadvantages and limits of the process are presented. Finally, the method is validated by comparison with wind tunnel measurements.
Baudet, Guillaume, Dutrion, Cecile, Lorenzi, Remi, Gendre, Felix, Geng, Shanshan
New Psychoacoustic Criteria for Turbocharger Aero Noise2019-01-14896/5/2019
With ever more stringent regulations related to air pollution and CO2 emissions, there is a growing trend to address this through the downsizing of automotive engines. Turbochargers are used to improve engine power by using exhaust gas energy to provide boosted air pressure for better efficiency. They are a key element in powertrains of today and in the future. During real operating conditions, the rotational speed of a turbo varies greatly making this rotating machinery run in “continuous transient” phases and produces unwanted noises as a result. Recently, we identified a new source of aero noise while developing a new type of turbocharger. Our typical in-house procedure for characterizing usual aero broad band noise source was to use the 3-microphone methodology for measuring the acoustic intensity. However, this methodology is not well adapted if the noise source is tonal, not constant over time and includes high frequency content, which is the case with the new type of turbocharger design and which could create bad noise perception in case of noise transfer into the vehicle cabin. As a result and first step, a set of new psychoacoustic criteria was studied to better understand the relationship between the turbocharger design and the noise content characteristics in addition to the existing methodology. Two new metrics called « Fluctuation Standard Deviation Ratio » and « Low Frequency Peak Emergence » were developed to fulfill this need. The “Fluctuation Standard Deviation Ratio” is assessed in the time domain and can be connected to the human perception of a «steam locomotive», which for a usual compressor flow noise can lead to connotations such as “feeling of unsafety”. The low frequency peak emergence is assessed in the frequency domain and relates to a perception of an annoying whistling sound, which is easily captured by human ears when the peak frequency is below 2 kHz - 3 kHz. Both criteria will be detailed in this paper. Their relevance with human perception will also be shown using practical examples.
Rigault, Alexandre, Kihm, Fred, Baron, Nicolas
Separation, Allocation and Psychoacoustic Evaluation of Vehicle Interior Noise2019-01-15186/5/2019
Besides optical and haptic criteria, the interior noise especially influences the quality impression of a vehicle. Separately audible disturbing noises are usually perceived as inadequate product quality. As a result, the reduction of disturbing noise components is a key factor for the overall product quality. Since the acoustic optimization is a complex and time consuming process, the need for an analysis tool which identifies automatically disturbing engine noise components within the vehicle interior noise is high. For this reason, a novel analysis tool has been developed which extracts tonal and impulsive engine noise components from the overall engine noise, and evaluates the annoyance of each noticeable engine component automatically. In addition, each disturbing noise is allocated to the emitting engine component. It is then possible to listen to each engine component noise individually and synthesize a target noise by superimposing manually weighted component noises. The noise separation into noise fragments is performed by means of the non-negative matrix factorization and image processing tools. These are then clustered according to their time correlation or other similarity-determining parameters. Classification algorithms are trained using chosen features to provide a noise source allocation. The extracted noise components as well as sound mixtures of those components are assessed by a psychoacoustic pleasantness rating metric. This metric is based on a multiple regression analysis between experimentally acquired pleasant values and objectively calculated psychoacoustic parameters as, e.g., loudness, sharpness, tonalness.
Schumann, Christian, Doleschal, Florian, Pischinger, Stefan, Verhey, Jesko
Fast Accurate Non-Destructive Measurement of Absorber Impedance and Absorption2019-01-15846/5/2019
Cabin acoustic comfort is a major contributor to the potential sales success of new aircraft, cars, trucks, and trains. Recent design challenges have included the increased use of composites, and the switch to electrically powered vehicles, each of which change the interior noise spectral content and level. The role of acoustic absorption in cabins is key to the optimisation of cabin acoustic comfort for modern vehicles, with acoustic impedance data needed in order to assess and optimise the impact of each component of a given lay-up. Measurements of absorbing interior trim are traditionally performed using either sample holder tests in a static impedance tube (impedance and absorption), or through tests in reverberation rooms (absorption only). Both of these procedures present challenges. In-tube absorption and impedance measurements are destructive, requiring highly accurate sample cutting and sealing. Reverberation room absorption measurements are subject to the effects of varying room diffusion, along with the impact of edge diffraction, sample geometry, and location. Finally, while non-destructive methods using hand-held probes also measure absorption, they are not able to measure impedance accurately. This paper describes fast non-destructive tests using a portable flanged impedance tube, and how they be used to quantify and optimise the absorption of interior trims. Measurements are made on non-locally reacting lay-ups, with the results corrected to equivalent in-tube results using a flanged-to-sample holder correction factor. The corrected flanged tube results are then compared with baseline in-tube measurements. Discussions address data quality and how the non-destructive measurements may be used to optimise lay-ups for increased absorption.
Murray, Paul B., Alexander, Jon, Kunio, Jason, Larsen, Flemming
An Acoustic Target Setting and Cascading Method for Vehicle Trim Part Design2019-01-15816/5/2019
One of the major concerns in the vehicle trim part design is the acoustic targets, which are generally defined by absorption area or coefficients, and sound transmission loss (STL) or sound insertion loss (SIL). The breaking down of acoustic targets in vehicle design, which is generally referred to as cascading, is the process of determining the trim part acoustic targets so as to satisfy full vehicle acoustic performance. In many cases, these targets are determined by experience or by subjective evaluation. Simulation based transfer path analysis (TPA), which traces the energy flow from source, through a set of paths to a given receiver, provides a systematic solution of this problem. Guided by TPA, this paper proposes a component level target setting approach that is based on the statistical energy analysis (SEA), an efficient method for vehicle NVH analysis in mid and high frequencies. Using a validated SEA model of the vehicle under consideration, the contributions of common noise sources and paths, which are generally defined on parts of sheet-metal with trim parts attached, can be evaluated. This allows the prediction of interior noise level due to various possible sound packages. On the base of this, acoustic target setting of trim parts can be defined as the solution of a mathematical optimization problem. The targets such as SIL of trim parts at certain frequency range are taken as design variables, and the vehicle level performance like the sound pressure level (SPL) at driver’s ear is incorporated into constraint functions. This approach is versatile and is suitable for traditional ICE vehicles and modern EVs. It can be used on a vehicle prototype at the early stages for target cascading, or on an existing vehicle model for NVH improvement. Several cases and examples on this target setting method have been discussed in the paper.
Wu, Weiwei, Ding, Peiran, Zi, Xiaowu, Liu, Beinan
A Research on Vehicle Gearbox Whine Based on Multi-Physics Coupling Simulation and Psychoacoustics2019-01-07794/2/2019
Vehicle gearbox whine is a common NVH problem which may directly cause complains from passengers on the quality and performance of vehicle. In order to efficiently and fundamentally control the whine phenomenon, this work first studied the characteristics and mechanisms of the gearbox vibration and noise. The study results revealed that the transmission error of gear was the excitation source of gearbox vibration, and the ambient air was the main transfer path of radiation noise. Then a multi-physics coupling simulation model was built to reveal the interactions among gear, housing and ambient air. This model could also predict the characteristics of the sound field near the passenger’s ear. To take account the psychoacoustic property of human auditory system, this work applied a quality index called tonality to evaluate the severity of gearbox whine. This paper also describes a case study to verify the accuracy and availability of the simulation model. In this case, the whine phenomenon of a practical gearbox was simulated with the proposed model first, and then an optimization on the micro geometry of gear was applied to decrease the noise level to an acceptable level. The main significance of this work is to propose an integrated and effective approach to control the gearbox whine. The indicative conclusions of this work could be referred by NVH engineers in the early phase of vehicle gearbox development.
Tang, Sicheng, Xu, Yong
Streamlined HMIs do more with less19TOFHP04_084/1/2019
The phrase “less is more” has been a major part of human-machine interface (HMI) designs for several years as developers traded multiple knobs and buttons for cleaner input techniques. However, the push to simplify the control's look and feel is offset by the need to let drivers and operators manage more things, often with redundant input techniques. The growing number of electronic features and functions comes as vehicle buyers demand controls that can be learned quickly. This need to manage more complex tasks without much training marks a major change from the era when operators slowly learned how to maneuver mechanical controls. New designs will need to further simplify the vehicle environments designed to provide more digital functionality.
Costlow, Terry
Investigation of Cabin Noise while Accelerating on Low Mu Track through Simulation Approach Using Full Vehicle ADAMS/Car Model2019-26-01791/9/2019
Cabin noise is a significant product quality criteria which enables the customers for product differentiation. There are various sources of cabin noise such as wind, structures(panels), engine, suspension, tire and roads. During product development phase, extensive tests has been conducted to improve vehicle dynamics behavior on various climatic conditions. One such test is accelerating vehicle on low mu or icy surface. While performing acceleration manoeuvre (tractions) on a low mu tracks, Cabin noise with source identified from front underbody & low tractive torque build up is reported. This undesirable behavior may occur due to following reason (1) Excitation of coupled modes between suspension and powertrain which induces torque fluctuation. (2) Transmissibility of various subsystem can be the reason for above problem statement. (3) Poorly chosen tire compounds and design leads to fluctuation in torque. A detailed simulation based study using ADAMS/CAR has been performed to assess the contribution of various full vehicle sub-systems, primarily suspension & powertrain sub-system towards the said problem statement. The dynamic interaction between road, suspension, powertrain and BIW has been is the focus of study both in time and frequency domain. This simulation helped understand the factor effects and contribution levels and correlates well with the subjective feel observed on the physical vehicle on low-mu track. This model has been further used to provide design recommendation on the compliance parameters to overcome the issue at hand. Test has been conducted with recommended tire grip properties and suspension bushing parameters which lead to reduction in cabin noise
Singh, Vivek, Prasad, Tej, Srivastava, Harshit
Low Frequency In-Cab Booming Noise Reduction in the Passenger Car2019-26-01711/9/2019
In-cab booming noise is low frequency (20 Hz∼300 Hz) phenomenon excites the cabin structure, which occurs mainly due to excitations from the powertrain, exhaust system, road input, etc. Annoyance due to booming noise affects the In-cab sound quality, which results in passenger discomfort. A diesel passenger car observed booming noise issue when operated at stationary as well as dynamic run-up conditions. In order to increase passenger comfort, experimental root cause analysis conducted on the vehicle to investigate the dominant sources for the cavity boom. Exhaust hanger and one of the engine mount identified as major reason for the booming noise in the cabin. A detailed study was carried out on dynamic property optimization of rubber hanger and possibility to relocate the hanger to improve the vibration transmissibility. Operational measurements conducted on vehicle by attaching finalized exhaust mount to confirm the significant booming noise reduction in the cabin.
Jawale, Pradeep, Karanth, Nagesh Voderahobli, Gaikwad, Atul Annasaheb, Mutalik, Keshav
Design Optimization of Engine Mount De-Coupler for Cabin Noise Refinement in Passenger Vehicle2019-26-01991/9/2019
Quieter cabins are indispensable in today’s evolving automobile industry. The effective isolation of vehicle noise and vibrations are essential to achieve the above. Since, low frequency powertrain induced NVH has been one of the major contributors affecting noise and vibration levels inside the passenger cabin. Thus, use of hydraulic mounts is a natural choice for all major OEMs. The objective of this study is to optimize the design of the hydraulic mount de-coupler unit, to reduce the abnormal noise felt inside the cabin. This condition was observed when the vehicle was driven at 20~30 km/h over undulated road surface, found very often in Indian drive conditions. Due to lack of accuracy and repeatability errors during NVH data acquisition in actual driving condition, the above road profile was captured and subsequently simulated in an acoustically treated BSR (Buzz, Squeak and Rattle) four poster simulator. Problem investigation and countermeasure validation were also performed in this facility. A significant improvement in cabin noise level by ~6 dB(A) in the problematic frequency zone, with the countermeasure, without negatively affecting any other NVH performance parameters, was achieved. A novel test methodology has been established for expedited root cause investigation & counter-measure validation of the problem statement. Design modification of the de-coupler membrane for eliminating such noise is a new approach.
Verma, Pallavi, Chatterjee, Joydeep, Bhadani, Priyesh, Ghosh, Chiranjit
Design, Simulation & Optimization of an Air Intake System to Reduce Induction Noise2019-26-01911/9/2019
Air intake system (AIS) plays a major role in reducing the noise level in passenger car compartment, which has become an important requirement due to increasing customer expectation for better in cab noise. The ideal air intake system design should have minimum possible noise at snorkel entry point which ultimately contributes in cabin noise. There are different techniques that are implemented for an air intake system noise reduction e.g. choosing proper location of air entry suction point in engine bay compartment, suitable design for air filter box (volume), duct designs etc. Further design improvement are possible with an addition of tuned resonators in the system. An addition of resonator have major effect seen in reducing air induction noise and to meet target Sound Pressure Levels (SPL). But at the same time, selecting the correct type of resonator, its position & volume, frequency/s band at which resonator is tuned are important parameters. The work presented here describes and compares the simulation results (GT POWER) with the measured SPL levels at different rpm range with different resonator types for Utility Vehicle (UV) as below, a Air intake system without resonator. b Multi-band resonator: resonator tuned for larger range of frequency band and requires more packaging volume. c Helmholtz resonator: resonator tuned for single frequency (for certain rpm at which peak observed) & requires less packaging volume. Based on the correlation developed between simulation and test results, the simulation models are useful for further refinement and proper selection of final optimum hardware. These simulation models are also further useful for future programs at design stage itself.
Patil, Ujwal, Rahane, Dnyanesh
Force Transmission Characteristics for a Loaded Structural-Acoustic Tire Model06-11-04-002510/23/2018
Concerns about tire noise radiation arise partly from city traffic planning, environmental protection, and pedestrian safety standpoints, while from the vehicle passengers’ perspective, noise transmitted to the vehicle interior is more important. It is the latter concern that is addressed in this article. Sound-absorbing materials generally offer good absorption at higher frequencies, but the reduction of relatively low frequency, structure-borne tire noise is a continuing focus of many auto manufacturers. A tire’s internal, acoustic cavity resonance is a very strong contributing factor to tire-related structure-borne noise, and it can easily be perceived by passengers. Some reduction of vehicle cabin noise can be achieved through the insertion of sound-absorbing material in the tires. However, apart from the additional cost for such tires, there is also an increased complexity when repairing them because of the need to avoid damaging the sound-absorptive lining. In that light, modifying the design of the tire-rim and suspension system to decrease the cavity noise influence without the addition of sound-absorbing material has a clear benefit. To that end, a fully coupled, structural-acoustic finite element tire model with rigid ground contact is described here. The model was established in the Abaqus/CAE 6.13-4 environment and was driven by a point force excitation at the leading edge of the contact patch. Tire surface velocities and hub center accelerations were calculated in order to study how the internal air cavity affects the force transmissibility characteristics of a tire structure. Simulation results have indicated that a match of the vertical cavity mode with an odd, circumferential flexural mode of the treadband can significantly increase the vibration levels transmitted from the tire to the rim center, and thence the hub and vehicle’s suspension. Thus it is suggested that changing the treadband stiffness to avoid such a match can significantly reduce the impact of the cavity resonance.
Cao, Rui, Bolton, J. Stuart
Squeak Noise Prediction for Systems with Dry Friction Damping2018-01-14836/13/2018
Squeak noise is a phenomenon which is often categorized as BSR, i.e. buzz, squeak and rattle. It arises from stick-slip movement between parts in contact. In a vehicle cabin, this noise is undesirable and has to be prevented. Simulation methods are used to find critical contact conditions in the construction at an early stage of development. For accurate predictions, these methods have to take nonlinear behavior into account. In this paper, the Harmonic Balance Method is applied to a three-dimensional finite element model in order to calculate vibrations of systems with dry friction contacts. The system’s sensitivity to different contact formulations is investigated. For a reference, a test rig has been built. It consists of a beam with harmonic excitation. The beam is clamped at one end. At the other end it is in dry friction contact with a plate. Different excitation levels, frequencies, normal contact forces and material pairs are evaluated. The system’s response in time and frequency domain is compared to corresponding simulation results. The contact definition is updated to achieve accuracy in calculated dynamic responses. Results of calculation can be used to estimate the radiated noise, e.g. by determining the Equivalent Radiated Power.
Weisheit, Konrad, Marburg, Steffen
Optimizing Vehicle NVH Using Multi-Dimensional Source Path Contributor Paradigm.2018-01-15426/13/2018
Automotive Industry is moving towards lightweight vehicle design with more powerful engines. This is increasing a demand for more optimized NVH design. Source-Path-Contributor (SPC) analysis is one of the ways to draw a holistic picture of any NVH problem. In this paper, an NVH problem of low frequency booming noise and steering vibration has been studied in a development vehicle. All three dimensions of SPC paradigm were looked at to propose a feasible and optimized solution at each level of Source, Path and Contributor model. A classical transfer path analysis (TPA) has been done to identify the highest contributing path: transmission mount and suspension arm. Optimization of suspension bush parameter has been carried out using dynamic elastomer testing facility for an improved NVH performance. After identifying source as engine a study of torsional fluctuations due to gas pressure and torsional resonances has been carried out in order to achieve a feasible solution at source. Finally, for contributor, operation deflection shapes have been studied to identify major panels responsible for the amplification of in-cabin noise. Optimized designs of dynamic dampers have been created using CAE tools and dynamic elastomer testing machine to propose an effective and efficient solution. This kind of approach was helpful to identify root cause at source, path and contributor levels, thereby helping to achieve an optimized NVH solution in terms of cost, weight and development feasibility.
Gupta, Gaurav, Singh, Vivek
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
The Effects of Suspension Component Stiffness on the Road Noise: A Sensitivity Study and Optimization2018-01-15106/13/2018
This paper investigates the sensitivity of stiffness of front and rear suspension systems on the structure-borne road noise inside a vehicle cabin. A flexible multi-body dynamics based approach is used to simulate the structural dynamics of suspension systems including rubber bushings, suspension arms, a subframe and a twist beam. This approach can accurately predict the force transfer to the trimmed body at each suspension mounting point up to a frequency range of 0 to 300 Hz, which is validated against a force measurement test using a suspension test rig. Predicted forces at each mounting point are converted to road noise inside the cabin by multiplying it with experimentally obtained noise transfer functions. All of the suspension components are modeled as flexible bodies using Craig-Bampton component mode synthesis method. To conduct a sensitivity analysis of the rubber bushings’ stiffness, an accurate nonlinear dynamic model of rubber bushings is constructed and validated against sample specimen tests. This model is based on a modified dual Kelvin-Voigt model and the Bouc-Wen hysteresis model to simulate the complex nonlinear behavior of the rubber bushing; both the frequency and amplitude dependent characteristics of the viscoelastic material are taken into account. The dynamic stiffness of the rubber bushings is changed from 50 to 150 percent to identify the sensitivity of each bushing on the road noise. To study the effect of rigidity of the suspension arms and frames on the road noise, Young’s moduli of the components are changed to examine corresponding sensitivity. Based on the identified sensitivity information, optimization of the bushing stiffness is conducted. The results and process introduced in this paper has been applied to the early stage development process of a C-segment chassis platform.
Kim, Joong-Kwan, Lee, Jinmo, Kim, Hyoung-Gun, Cho, Munhwan, Ih, Kang-Duck, Ko, Han-Young, Shim, Jeong-Soo
Interior Noise Refinement in an ICV Bus through Driveline Torsional Vibration Analysis2018-01-14726/13/2018
With a push for urbanization across cities, there is an increased demand for mobility in public transportation especially buses which are provided through state transport undertakings. Hence, the expectations of this class of vehicles will be high in terms of quality and comfort to the passengers. The noise inside the passenger area of the bus becomes an important parameter, which sets apart a bus manufacturer from its competitors. The driveline of the bus is the system responsible for the transfer of power from engine to the wheels. The noise and vibration problems associated with it are detected only in the late stages of the design chain, when all its elements are tested together over a wide range of conditions. Since, calibration of engine and the selection of transmission is freezed in early stages, satisfying power and torque requirements, the only viable option left to address the problem is by optimizing the clutch parameters. Combustion in multi-cylinder four stroke diesel engine produces periodically changing gas and inertia forces associated with reciprocating pistons. This leads to fluctuation in the engine speed and the torque transmitted by the engine, inducing torsional vibrations into the system. These torsional vibrations make the unloaded gear pairs of the gearbox to impact against each other generating Gear rattle noise. In the present work, an abnormal noise was observed in an ICV (Intermediate Commercial Vehicle) bus at both idling and driving conditions. Near source noise measurements and interior noise measurements were carried out to determine the source of the noise. Torsional vibration levels were also measured at engine and gearbox. Upon identification of the source, the clutch parameters including the clutch torsion spring stiffness was scrutinized and modified. This gave improvement in the interior noise levels inside the passenger area of the bus.
Kamani, Keval, Kannan, P, P, Sivaraman
Explanation for Variability in Lower Frequency Structure-Borne Noise and Vibration: Roles of Rear Subframe Dynamics and Right-Left Spindle Phasing10-02-01-00025/17/2018
This investigation focuses on a class of rear suspension systems that contain both direct and intersecting structural paths from the tire contact patches to the vehicle body. The structural paths intersect through a dynamically active rear subframe structure. New experiments and computational models are developed and analyzed in this article to investigate the variability of structure-borne noise and vibration due to tire/road interactions in the lower- to mid-frequency regimes. Controlled operational experiments are conducted with a mass-production minivan on a chassis dynamometer equipped with rough road shells. Unlike prior literature, the controlled experiments are analyzed for run-run variations in the structure-borne noise up to 300 Hz in a single vehicle to evaluate the nature of excitations at the spindle as the key source of variation in the absence of significant manufacturing, assembly and instrumentation errors. Further, a deterministic modal expansion approach is used to examine these variations. Accordingly, an illustrative eleven-degree-of-freedom lumped parameter half vehicle model is developed and analytically utilized to demonstrate that left-right spindle excitation phasing dictates the participation of the subsystem vibrational modes in the system forced response. The findings are confirmed through the analysis of a reduced finite element model of the vehicle system with a high-fidelity, modally dense suspension model, where the left-right rolling excitation phasing at the spindle alone is found to affect the component dynamic vibration amplitudes up to ±30 dB depending upon the component location and frequency range. These results are in qualitative agreement with the type of variations observed in the experiments.
Noll, Scott, Singh, Rajendra
An Objective Assessment Method of Combustion Noise Characteristics in Vehicle Interiors2018-01-12834/3/2018
To increase the efficiency of measures targeting combustion noise in complete vehicle development, the authors developed a new sound quality evaluation method by combining two known methods: the time domain combustion noise separation method (T-CNSM) and a psychoacoustic metric, fluctuation intensity. The T-CNSM was applied to the vehicle interior noise, allowing for precise extraction of the combustion contribution in the time domain. Furthermore, the T-CNSM has enabled a sound quality check of combustion noise using a headphone-playback system. The procedure of this method is as follows. Firstly, simultaneous measurement of vehicle interior noise and in-cylinder pressure of each cylinder is carried out under acceleration. Afterward, the application of digital signal processing using Fourier transform and multiple regression analysis to the measured data extracts the contribution of combustion noise from the vehicle interior noise in the time domain. Subjective evaluation tests using Scheffe’s paired comparison method were conducted with 14 noise, vibration, and harshness (NVH) development experts via a headphone-playback system. Multiple types of combustion noise in vehicle interiors obtained by the T-CNSM were used for the presentation sound. Based on the results of the subjective evaluation tests, the dissonant combustion noise index (DCNI) was developed as a new objective evaluative index for the sound quality of combustion noise, using fluctuation intensity as a psychoacoustic metric expressing intensity of perceived fluctuation such as rumbling, rattling, and knocking. The new evaluation method combined the DCNI with the T-CNSM and has made it possible to quantify the high-precision sound quality of the combustion noise in vehicle interior, which is inexpressible with conventional A-weighted sound pressure levels (SPL). This article provides an overview of this evaluation method’s procedure series and discusses the validity of this method when applied to the comparison of combustion noise sound quality in three mass production Japanese Kei car models.
Torii, Kenji, Noumura, Kousuke
Research of Effect of Electric Powertrain on Vehicle Noise2018-01-12824/3/2018
A low-speed and heavy-duty electric powertrain was selected as the research object, the influence of electric powertrain characteristics on whole vehicle noise under accelerating condition (Speed range 800 r∙min−1~2200 r∙min−1; Torque range 500 N∙m~960 N∙m) was studied. Considering the traveling characteristics around the city, the interior and powertrain noise were recorded as the accelerating working range (10 km/h~50 km/h). Based on recording data, combining the noise generation mechanism of the motor and transmission, the components of the interior noise and motor/transmission noise were analyzed qualitatively using the order spectrum analysis; the contribution of the electric powertrain noise components to the interior were calculated quantitatively using the partial coherence analysis method; finally the measuring and analyzing methods of effect of electric powertrain on interior were built, which provided certain theoretical support for further improving the noise of electric powertrain and whole interior. Results shown that when the vehicle is running during 3rd gear, the noise in the vehicle is mainly caused by the shifting gear noise, Constant-mesh gear engagement noise and the stator tooth groove harmonic noise. When the speed is 20 km/h and 25 km/h, the noise is mainly affected by the gearbox. When the speed is 35 km/h and 40 km/h, the noise is mainly affected by the motor.
Liu, Hai, Ma, Kunqi, Yu, Hanzhengnan
Evaluation and Improvement of Greenhouse Wind Noise of a SGMW SUV using Simulation Driven Design2018-01-07374/3/2018
At SAIC-GM-Wuling (SGMW) the greenhouse wind noise performance of their vehicles has gained a lot of attention in the development process. In order to evaluate and improve the noise quality of a newly developed SUV a digital simulation based process has been employed during the early stage of the design. CFD simulation was used for obtaining the flow induced exterior noise sources. Performance metrics for the quality were based on interior noise levels which were calculated from the exterior sources using a SEA approach for the noise transmission through the glass panels and propagation to the driver’s or passenger’s head space. Detailed analysis of the CFD results allowed to identify noise sources and related flow structures. Based on this analysis, design modifications were then applied and tested in a sequential iterative process. As a result an improvement of more than 2 dB in overall sound pressure level could be achieved.
Hou, Zhaoping, Fu, Nian, Huang cEng, Yuanyi, Lv, Juncheng, Shen, Yantao, Huang, Hongyan, Wu, Long, Xie, Weiliang, Friz, Heinz
Investigation of Interior Noise from Generic Side- View Mirror Using Incompressible and Compressible Solvers of DES and LES2018-01-07354/3/2018
Exterior turbulent flow is an important source of automobile cabin interior noise. The turbulent flow impacts the windows of the cabins to excite the structural vibration that emits the interior noise. Meanwhile, the exterior noise generated from the turbulent flow can also cause the window vibration and generate the interior noise. Side-view mirrors mounted upstream of the windows are one of the predominant body parts inducing the turbulent flow. In this paper, we investigate the interior noise caused by a generic side-view mirror. The interior noise propagates in a cuboid cavity with a rectangular glass window. The exterior flow and the exterior noise are computed using advanced CFD methods: compressible large eddy simulation, compressible detached eddy simulation (DES), incompressible DES, and incompressible DES coupled with an acoustic wave model. The last method is used to simulate the hydrodynamic and acoustic pressure separately. The pressure fluctuations of the flow and noise are imposed on the window in the computation of the interior noise, but the reversal effect of the window vibration feeding back on the flow is neglected in the flow simulation. The localized flow characteristics are discussed. The energetic surface pressure appears in the regions where the shear layer from the mirror side edge impinges on the window. The contributions of the hydrodynamic and acoustic pressure to the interior noise are quantified. The acoustic component is found to be more efficient in the interior noise generation and to play the dominant role at high frequencies.
Yao, Huadong, Davidson, Lars, Chroneer, Zenitha
Acoustic Modeling for Three-Dimensional Lightweight Windshields2018-01-01414/3/2018
In the auto industry, lightweight window designs are drawing more attention for improved gas mileage and reduced exhaust emission. Corning’s Gorilla® Glass used in laminate design enables more than 30% weight reduction compared to conventional soda-lime glass laminates. In addition, Gorilla® Glass hybrid laminates (which are a laminate construction of a thick soda-lime glass outer play, a middle polyvinyl butyral interlayer, and a thin Gorilla Glass inner ply) also show significantly improved toughness due to advanced ion-exchange technology that provides high-surface compression. However, the reduced mass also allows increased transmission of sound waves through the windshield into the vehicle cabin. A system-level measurement approach has always been employed to assess overall vehicle acoustic performance by measuring sound pressure levels (SPL) at the driver’s ears. The measured sound signals are usually a superimposition of a variety of noise sources and transmission paths. It is challenging to quantitatively isolate the impact of replacing a thick windshield with a thin windshield. A reverberation room measurement is another standard component-level testing approach but it is usually limited to flat glass evaluation. To enhance understanding of sound wave transmission through windshields, a 3D windshield acoustic model was developed using ANSYS Acoustics ACT. The model was validated for a 24″ x 24″ flat laminated panel with reverberation data. It was then extended for simulating a 3D production windshield with curved surface and tri-layer polyvinyl butyral (PVB) interlayer. The model has been employed to characterize windshield acoustic performance under either plane wave incidence or diffuse field. Through modeling simulation, an optimal inner layer glass thickness was identified at 1 mm which is able to maximally shift critical frequency further away from human being’s sensitive hearing range while maintaining reasonable sound transmission loss (STL) at damping control region. Windshield geometry was also evaluated and impact observed especially on transmission loss at spectra regions below the critical frequency.
Yu, Chao, Bhatia, Vikram
Challenges of Hydraulic Engine Mount Development for NVH Refinement2018-01-06814/3/2018
NVH refinement of passenger vehicle is essential to customer acceptance for premium or even mid-size segment passenger cars. Hydraulic engine mount is becoming common for these segments to reduce engine bounce, idle shake and noise transfer to passenger cabin. Modern layout of hydraulic mount with integrated engine-bracket and smaller size insulator has made it cost-effective to use due to reduction of cost gap from conventional elastomeric mounts. However the downsizing and complex internal structure may create some new types of noises in passenger cabin which are very difficult to identify in initial development stage. Main purpose of hydraulic mount is to provide high damping at low-frequency range (6~15 Hz) and to isolate noise transfer from combustion engine to passenger cabin within wide frequency range (15~600 Hz).This paper emphasizes on challenges and problems related to hydraulic mount development. Tuning of Hydraulic mount is required to avoid cavitation noise at low-frequency and also any abnormal noise due to hydraulic unit resonance at higher frequency. Design measures to curb NVH problems, e.g. cavitation noise, bump noise of mount stopper, resonance from hydro unit, at early development stage are explained in the paper.
Ghosh, Chiranjit, Parmar, Aashish, Chatterjee, Joydeep
Automotive Vehicle Brake Squeal Test Recommend PracticeJ2625_201707 (Current)7/24/2017
This procedure is applicable to squeal type noise occurrences for passenger car and light truck type vehicles that are used under conventional operating conditions. For the purposes of this test procedure, squeal is defined as occurring between 900 and 18 000 Hz.
Brake NVH Standards Committee
Quantitative Evaluation of Steering System Rattle Noise2017-28-19527/10/2017
Today’s automotive industry in the process of better fuel efficiency and aiming less carbon foot print is trying to incorporate energy saving and hybrid technologies in their products. One of the trends which has been followed by Original Equipment Manufacturers (OEMs) is the usage of Electric Power Steering (EPS) system. This has been an effective option to target fuel saving as compared to hydraulically assisted power steering system. EPS has been already tested successfully, not only on system level but also on vehicle level for endurance and performance by OEMs as per their norms and standards. Over the decade, NVH (noise, vibration & harshness) have become one of the touch points for customer perception about vehicle quality. This leads us to a commonly perceived problem in EPS or manual type steering system i.e. rattle noise. In this paper, a methodology has been highlighted for detection, identification and measurement of steering rattle noise and hence identifying the noise source in the steering system by fundamentally correlating measured data of noise and vibration.
Sharma, Utkarsh, Wilson, Simson T., Lalasure, Santosh, Rajakumar, K.
Noise and Vibration Measurement Methods for Large Diameter Single-Piece Aluminum Propeller Shafts2017-01-17756/5/2017
This paper describes recently developed test methods and instrumentation to address the specific noise and vibration measurement challenges posed by large-diameter single-piece tubular aluminum propeller (prop) shafts with high modal density. The prop shaft application described in this paper is a light duty truck, although the methods described are applicable to any rotating shaft with similar dynamic properties. To provide a practical example of the newly developed methods and instrumentation, impact FRF data were acquired in-situ for two typical prop shafts of significantly different diameter, in both rotating and stationary conditions. The example data exhibit features that are uniquely characteristic of large diameter single-piece tubular shafts with high modal density, including the particular effect of shaft rotation on the measurements. Observed differences in the data between the static and rotating operating conditions are examined, and observed frequency shifts are explained by coordinate transformation from the stationary sensor locations to the rotating shaft. Empirically-adjusted frequency shift equations are then provided and compared to the measured data. As a final note, the suitability of the experimental and theoretically predicted data for CAE model correlation is discussed.
Gehringer, Mark A., Considine, Robert, Schankin, David
Digital Aeroacoustics Design Method of Climate Systems for Improved Cabin Comfort2017-01-17876/5/2017
Over the past decades, interior noise from wind noise or engine noise have been significantly reduced by leveraging improvements of both the overall vehicle design and of sound package. Consequently, noise sources originating from HVAC systems (Heat Ventilation and Air Conditioning), fans or exhaust systems are becoming more relevant for perceived quality and passenger comfort. This study focuses on HVAC systems and discusses a Flow-Induced Noise Detection Contributions (FIND Contributions) numerical method enabling the identification of the flow-induced noise sources inside and around HVAC systems. This methodology is based on the post-processing of unsteady flow results obtained using Lattice Boltzmann based Method (LBM) Computational Fluid Dynamics (CFD) simulations combined with LBM-simulated Acoustic Transfer Functions (ATF) between the position of the sources inside the system and the passenger’s ears. It provides an approximation of the contribution of each noise source to the passenger’s ear locations. By identifying and quantifying noise sources, this method guides engineers at treating the main sources in confined systems, usually a daunting task experimentally. In a first part, the accuracy of this numerical approach is investigated by comparing predicted aeroacoustics results to measured data: in a first step for a simple lateral duct with vent; in a second step for a HVAC unit in fresh air ventilation mode. In a second part, the Flow-Induced Noise Detection Contributions method is used to highlight the location and intensity of the various noise sources for the different operating conditions. In the third and last part, limited modifications are made to the HVAC system geometry within design constraints, and LBM simulations are performed on the modified design to numerically assess the reduction of the noise levels.
Biermann, Jan, Mann, Adrien, Neuhierl, Barbara, Kim, Min-Suk
A New Strategy Optimization Method for Vehicle Active Noise Control Based on the Genetic Algorithm2017-01-18316/5/2017
The control strategy design of vehicle active noise control (ANC) relies too much on experiment experience, which costs a lot to gather mass data and the experimental results lack representation. To solve these problems, a new control strategy optimization method based on the genetic algorithm is proposed. First, a vehicle cabin sound field simulation model is built by sound transfer function. Based on the filtered-X Least Mean Squares (FX-LMS) algorithm and the vehicle cabin sound field simulation model, a vehicle ANC simulation model is proposed and verified by a vehicle field test. Furthermore, the genetic algorithm is used as a strategy optimization tool to optimize an ANC control strategy parameter set based on the vehicle ANC simulation model. The optimized results provide a reference for the ANC control strategy design of the vehicle.
Li, Longchen, Huang, Wei, Ruan, Hailin, Tian, Xiujie, Zhu, Keda, Care, Melvyn, Wentzel, Richard, Chen, Xiaojun, Zheng, Changwei
Items per page:
1 – 50 of 461