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2015-06-15
Technical Paper
2015-01-2254
WenbIn Shangguan
The driving pulley in the Engine Front End Accessory Drive System (EFEAD) is usually used as a torsional vibration damper for the crankshaft. Although the crankshaft torsional vibrations are dampened, the torsional vibration is absorbed by the inertia ring of the driving pulley and then is transmitted to the EFEAD. The isolation pulley is a new device and is to reduce the belt tension fluctuation by isolating the belt transmission from the crankshaft torsional vibrations. In the isolation pulley, there are two inertia rings, one is used to damp the crankshaft vibration and another one is to drive the EFEAD. The purpose of this paper is to study design method for isolation pulley to reduce the EFEAD vibrations. An EFEAD with five-pulley system and isolation pulley is taken as studying example and a non-linear model is established to predict the dynamic response of the pulleys, tensioner motion and pulley slips.
2015-06-15
Technical Paper
2015-01-2252
Haixin Dai PhD, Weikang Jiang, Yuanyi Huang cEng
Engine mounting plays an important role to interior noise of automobiles. Decoupling optimal design of mounting has been researched for long, but vibration power into body transmitted from engine can be a more intuitive way to improve NVH performance. Some approach for minimizing transfer power through engine mount based on finite element model was reported, whose disadvantages are lack of data and inaccuracy at high frequency in some cases. To get an analytic formula of transmitted power, a model considering coupled vibration between bodywork and engine is presented here. In this model, the engine is modeled as a rigid body, the rubber mounts are modeled as springs and dampers, and the bodywork is modeled as flexible. An impedance function matrix is used to describe the dynamic relationship between the mounting points on the body.
2015-06-15
Technical Paper
2015-01-2336
Anastasios Arvanitis, Jeff Orzechowski, Todd Tousignant, Kiran Govindswamy
Automotive companies are looking into adding extra value to their vehicles by enhancing powertrain sound quality. The objective is to create a brand sound that is unique and preferred by their customers since quietness is not always the most desired characteristic, especially for high-performance products. This paper describes the process of developing a brand powertrain sound for a high-performance vehicle using the DFSS methodology. Initially the customer’s preferred sound was identified and analyzed. This was achieved by subjective evaluations through voice-of-customer clinics using vehicles of similar specifications. Objective data were acquired during several driving conditions. In order for the design process to be effective, it is very important to understand the relationship between subjective results and physical quantities of sound. Several sound quality metrics were calculated during the data analysis process.
2015-06-15
Technical Paper
2015-01-2335
Scott Amman, Francois Charette, Paul Nicastri, John Huber, Brigitte richardson, Gint Puskorius, Yuksel Gur, Anthony Cooprider
Quantifying Hands-free Call Quality in an Automobile Hands-free phone use is the most utilized use case for vehicles equipped with infotainment systems with external microphones that support connection to phones and implement speech recognition. Critically then, achieving hands-free phone call quality in a vehicle is problematic due to the extremely noisy nature of the vehicle environment. Noise generated by wind, mechanical and structural, tire to road, passengers, engine/exhaust, HVAC air pressure and flow are all significant contributors and sources of noise. Other factors influencing the quality of the phone call include microphone placement, cabin acoustics, seat position of the talker, noise reduction of the hands-free system, etc. This paper describes the work done to develop procedures and metrics to quantify the effects that influence the hands-free phone call quality.
2015-06-15
Technical Paper
2015-01-2332
Jan Deleener, Akira Sekitou, Masanori OHTA
Shift feeling is an important comfort attribute for manual transmission driven vehicles. For front-wheel-drive vehicles, there are 3 main parts of interest: the gearbox, the shifter and the shift cable. Often only a test based evaluation process on the actual assembly is available in the later stages of development. In order to frontload the shift feeling evaluation a virtual simulation process is required. For the shift lever and the gearbox there are well established models available. With 3D multibody models or even 2D planar models the effect of kinematics and compliances like connection stiffness and friction are already studied today. However, the modelling of the transmission cable, connecting the gearbox and the shifter remains a challenge to accurately represent the physical feel. By experience it was known that the 3D positioning and curvature of the cable affected the friction force and therefore the shift feeling.
2015-06-15
Technical Paper
2015-01-2219
Al Ganeshkumar, Shinichi Fukuhara
Active Noise Cancellation technology is widely used in automobiles to reduce engine harmonic noise. ANC systems require one or more microphones mounted in the cabin to monitor the harmonic noise level and provide feedback to the DSP algorithm. The ideal locations for the microphones are as close as possible to the passenger seating locations and away from any wind turbulence that can hit the diaphragm of the microphone. Excessive wind turbulence on the diaphragm can cause the ANC adaptive filter weights to be perturbed enough and cause audible ‘pumping’ type artifacts. For several practical reason it’s not always possible to control the location of the microphones and hence a DSP software and/or mechanical solution often needs to incorporated in the system. This paper will primarily address the DSP software solutions to detect wind turbulence noise in ANC microphones so appropriate counter-measures can be applied to eliminate the unwanted artifacts.
2015-06-15
Technical Paper
2015-01-2272
Pradeep Dinkar Jawale, E Ramachandran, Nagesh Voderahobli Karanth, Ammar Ali
Day by day, customer expectations for comfort in the vehicle interior are driving automotive manufactures to provide better environment in their vehicles. Considering the ongoing developments in diesel powered engines and vehicles in India, the necessity of noise reduction has become more relevant. In such a scenario, NVH benchmarking has become very critical for new product development. Also, given the increasing customer awareness, noise and vibration have also become indicators of overall vehicle perception and hence provide crucial inputs for NVH design, optimization and target setting. In this paper, two families of diesel powered cars in India have been evaluated for their NVH performance, both for exterior & interior noise to arrive at noise & vibration contribution relevant to passenger comfort in order to quantify contribution of powertrain, tyre, wind etc. to the overall noise and their trends are presented.
2015-06-15
Technical Paper
2015-01-2201
Paul B. Murray, Jason T. Kunio, Leif Christensen, Flemming S. Larsen
Acoustic material testing is becoming increasingly relevant to engineers, designers and manufacturers from a broad range of industries. This paper presents comparisons between material absorption measurements made using the traditional approaches of the reverberation room method and the fixed impedance tube using a sample holder, and compares the results with those obtained using a new portable flanged impedance tube method. The portable tube allows fast non-destructive in-situ material measurements. They therefore include the impact of the installed lay-up (e.g. effects of facing sheets, curvature, material compression, bagging, etc). Comparison between the varying measurement techniques shows that the portable meter data are more repeatable than both the reverberation room and sample holder procedures. The repeatability of the reverberation room absorption results is subject to variations in panel edge diffraction, non-diffuse field conditions, and source/ receiver repeatability.
2015-06-15
Technical Paper
2015-01-2265
Murali Balasubramanian, Ahmed Shaik
Automotive manufacturers are being challenged to come up with radical solutions to achieve substantial (30-35%) vehicle weight reductions without compromising Safety, Durability, Handling, Aero-thermal or Noise, Vibration and Harshness (NVH) performance. Developing light weight vehicle enablers have assumed foremost priority amongst vehicle engineering teams in order to address the stringent Fuel Economy Performance (FEP) targets while facilitating lower CO2 emissions, downsizing of engines, lower battery capacities etc. Body sheet metal panels have become prime targets for weight reductions via gage reduction, high strength steel replacement, lighter material applications, lightening holes etc. Many of these panel weight reduction solutions are in sharp conflict with NVH performance requirements.
2015-06-15
Technical Paper
2015-01-2266
Andrzej Pietrzyk
Several of the exterior noise sources existing around a vehicle can cause airborne noise issues at relatively low frequencies. One of them is exhaust pipe orifice noise. Traditional methods for handling airborne noise in vehicles, such as SEA, are not suitable for the frequency range of interest. Finite Element analysis has been used, but it often ends up with very heavy runs if semi-infinite acoustic elements are used at the outer boundary as the solution has to be direct instead of modal in this case. There are, however, some softwares that can handle this calculation relatively efficiently. One of the primary choices could be FFT&Actran. However, recently, a similar capability has been developed in MSC Nastran. Also, the calculations involving the free field impedance conditions have been made extremely efficient in CDH/AMLS. Including the poro-elastic material model for foam-based carpets is also becoming practically possible.
2015-06-15
Technical Paper
2015-01-2301
Maxwell Hill, Dan Luo, Mark Moeller
Wind noise can be a significant event for automotive design engineers. The greenhouse glass plays an important role in the wind noise process. Robust estimates of the greenhouse glass damping are necessary for both understanding and modeling the role of the glass in the wind noise process. One unanswered question is whether the aerodynamic loads affect the window glass damping. To make this determination a method to assess the operational damping is required. The civil engineering community uses the random decrement technique to assess operational damping due wind loads. The random decrement technique has been shown to be a normalized autocorrelation function. In this paper the damping is estimated directly from the autocorrelation function. In the first section the relationship between the damping and autocorrelation function is examined for white noise excitation. A single oscillator is examined as the first case. Extension to higher modal densities is discussed.
2015-06-15
Technical Paper
2015-01-2257
Ki-Chang Kim, Sang-Woo Lee, Seok-Gil Hong, Jay Kim, Gil-Jun Lee, Jae Min Choi, Yong-Jin Kim
Recently, in automobile industry, squeak and rattle (S&R) in body structure and trim parts has become a very significant issue in Initial Quality Study (IQS). In this study, a new CAE process developed by the authors to reduce S&R noises in the door system is reported. Friction-induced vibration and noise generation mechanism of a door system are studied numerically. The effect of degradation of plastics used in door trims is studied by using a model obtained from experiments. Effects of changes of material properties such as Young's modulus and loss factor, due to the material degradation as well as statistical variations are predicted using, several cases of door systems. As a new concept, the rattle and squeak index is proposed, which can be used to guide design of the body structure and trim parts. The predicted of S&R in the door system, from the proposed CAE process were compared to those obtained from the experiment.
2015-06-15
Technical Paper
2015-01-2267
Youngha Kim, Choonhyu Kim, Jaewoong Lee, Sunggi Kim
This paper describes structure borne noise reduction process that was using a combination of experimental and analytical methods. First, Major noise paths was identified using experimental Transfer Path Analysis (TPA). Next, FEA-Experimental modeling and forced response simulation were conducted using the Hybrid FEA-Experimental FRF method. Hybrid FEA-Experimental FRF-Based Substructuring (FBS) model was used along with Operational Deflection Shape (ODS) and Modal Analysis. The Hybrid FEA-Experimental model consisted of an experimental FRF representation of the body and a finite element model of sub-frame. The finite element of sub-frame is created by using Altair HyperMesh from CATIA images and dynamic analysis is carried out by using MSC Nastran. The natural frequency and frequency response function of finite element sub-frame model are compared with them of real sub-frame for the validity of applying Hybrid FBS method.
2015-06-15
Technical Paper
2015-01-2360
Todd Freeman, Gabriella Cerrato
Source-path-contribution (SPC) analysis, or transfer-path-analysis, is a test based method to characterize noise and vibration contributions of a complex system. The methodology allows for the user to gain insight into the structural forces and acoustic source strengths that are exciting a system, along with the effects of the structural and acoustic paths between each source and a receiver position. This information can be utilized to understand which sources and/or paths are dominating the noise and vibration performance of a system, allowing for focused target cascading and streamlined troubleshooting efforts. The SPC process is widely used for automotive applications, but is also applicable for a wide range of product types. For each unique application the basic SPC principles remain constant, however best practices can vary for both measurement and analysis depending on the type of system being evaluated.
2015-06-15
Technical Paper
2015-01-2197
Stijn Vercammen, Fabio Bianciardi, Peter Kindt, Wim Desmet, Paul Sas
In the context of the reduction of traffic-related noise the research reported in this paper contributes to the development of low noise tyres. Two measurement techniques have been analyzed for exterior noise radiation characterization of a loaded rotating slick tyre on a rough road surface. On one hand sound pressure measurements at low spatial resolution with strategically placed microphones on a half-hemisphere around the tyre/road contact point have been performed. This technique provides a robust solution to compute the (overall) sound power level. On the other hand sound intensity measurements at high spatial resolution by means of a scanning intensity probe, LMS Soundbrush, have been performed. This technique allows a more detailed spatial visualization of the noise radiation and helps in getting more insight and better understanding of the acoustical phenomena.
2015-06-15
Technical Paper
2015-01-2200
Guojian Zhou, Xiujie Tian, Keda Zhu, Wei Huang, Richard E. Wentzel, Melvyn J. Care
Acoustic performance of auto interiors is definitely important to control the NVH performance inside a vehicle, and it is determined by the material parameters (porosity, air flow resistance, tortuosity, viscous characteristic length, thermal characteristic length, density, Young’s modulus, Poisson’s ratio, damping coefficient, and thickness). First, by making different felt samples (of different surface density and thickness), the acoustic performance and related parameters were obtained. Then the correlation between the parameters and the acoustic performance was summarized, and the sensitivity of different parameters on the acoustic performance was demonstrated. Through this method material parameter database can be established based on real materials and together with the sensitivity analysis sound package design and adjusting can be easily conducted.
2015-06-15
Technical Paper
2015-01-2205
John G. Cherng, Simeng xing, Weiwei Wu, Jan Ladewig, Rolf Balte, Maurice Venegas
A comprehensive and systematic investigation on acoustical performance of carbon nanotube enhanced polyurethane (PU) foams was performed. The complete foam making process was carefully carried out in order to select a stable base foam composition that to be integrated with many carbon nanotube materials. A total of eight design parameters were evaluated, such as loading in weight percentage, diameter of the nanotube, length of the nanotube,coating with Ni, single and multiple layer nanotubes, graphitization of nanotube, radical bonding, and geometry configuration of nanotube, i.e. tube vs. sheet. Both normal incidence sound transmission loss (STL) and absorption coefficient were measured. It was found out that there is an optimum value in most of design parameters. In general, nanotube enhanced PU foam definitely demonstrated improvements in both absorption coefficients and sound transmission loss.
2015-06-15
Technical Paper
2015-01-2263
Saeed J. Siavoshani, Prasad Vesikar
The intent of this paper is to summarize a comprehensive test-based approach developed at Siemens to analyze the door closing sound using structural and acoustic loads developed during the event. This study looks into the door closing phenomena from the structural interaction point of view between the door and the body of the vehicle. This method provides the design modification direction to improve the door closing sound and its quality. The study also quantifies the structural and acoustic loads developed at the interface mechanisms at the door-to-body frame interface during the impact event. Considering the transient nature of the door-closing event, a time domain transfer path analysis methodology is used to indirectly quantify the loads being developed between the latch and striker and different faces of door frames and body interfaces. The paper also predicts the equivalent acoustic loads developed at the interfaces between the door frame and the body.
2015-06-15
Technical Paper
2015-01-2270
Oliver Unruh, Christopher Blech, Hans Peter Monner
Global attenuation of structural velocities is one of the most effective approaches in order to reduce noise emitted by shell structures such as a car roof or aircraft fuselage panels. This global reduction can be achieved by the application of passive damping treatments like constraint layer damping on large fractions of the vibrating surface. The main disadvantage of this approach is the fact that it leads to increasing total cost and weight of the structure. To overcome this problem, acoustic black holes can be used to focus the energy of structure borne sound on some critical locations of the structure in order to dissipate it by a very limited application of damping treatments. Acoustic black holes are funnel shaped thickness reductions that attract sound radiating bending waves and allow a global vibration reduction by an acceptable use of additional damping.
2015-06-15
Technical Paper
2015-01-2262
Tom Knechten, Peter Van der Linden, Marius-Cristian Morariu
Structural and vibro-acoustic transfer functions still form an essential part of NVH data in vehicle development programs. Excitation in the three DOFs at all body interface connection locations to target responses gives information on local dynamics stiffness and the body sensitivity for that specific path in an efficient manner. However, vehicles become more compact for fuel efficiency and production costs and to meet the market demand for urban vehicles. Alternative driveline concepts increase the electronic content and new mount locations. To achieve the optimum on road noise NVH, handling performance while conserving interior space and trunk volume requires a complex suspension layout. On top of that, customers put weight on safety and comfort systems which result to a higher packaging density. These trends imply ever limiting accessibility of the interface connections on the body structure.
2015-06-15
Technical Paper
2015-01-2273
Curtis Jones, Zhengyu Liu, James Hurd III, Suhas Venkatappa
This paper presents the methodology of predicting vehicle level automotive air-handling system air-rush noise sound quality (SQ) using the sub-system level measurement. Measurement setup in both vehicle level and sub-system levels are described. To assess the air-rush noise SQ, both 1/3 octave band sound pressure level (SPL) and overall Zwicker's loudness are used. The "Sound Quality Transfer Functions (SQTF)" between sub-system level and vehicle level are developed for the specified climate control modes and vehicle segment defined by J.D. Power & Associates, while the Zwicker's loudness is calculated using the un-weighted predicted 1/3 octave band SPLs by the Matlab-based program. The predicting models are demonstrated in a fairly good agreement with the measured data. The methodology is applied to the development of sub-system SQ requirement for upfront delivery of the optimum design to meet global customer satisfaction.
2015-06-15
Technical Paper
2015-01-2264
Rama Subbu, Baskar Anthonysamy, Piyush Mani Sharma
In India, demand for motorcycle with good comfort is increasing among the customers thereby the vibration reduction of two wheelers is key parameter for motorcycle manufacturers. In order to overcome the demand in the market, manufacturers are giving more importance to ride comfort by reducing vibration experienced by the customer while using it. This results in the reduction of the life cycle of the vehicle models and drives the manufacturers to different product design philosophies and design tools, as one would expect. One of the performance factors that continue to challenge designers is that of vehicle longitudinal and vertical acceleration experienced by the motorcycle components. An essential tool in the motorcycle development process is the ability to quantify the durability of the component. This paper main objective is to increase the life of the motorcycle front fender through virtual simulation, on road testing and laboratory testing using NVH tool.
2015-06-15
Technical Paper
2015-01-2271
Yong Du Jun, Bong Hyun Park, Kang Seok Seo, Tae Hyun Kim, Myoung Jae Chae
An objective measure is proposed for seat riding comfort evaluation under low frequency (0~2 Hz) vibratory conditions which represents typical roll and pitch motions of driving motor vehicles. The related feeling due to this low frequency vehicle motion is termed ‘hold feeling’ because the seated body may tend to deviate from the defined seating position under such vehicle motion inputs. In the present study, dynamic pressure distribution measurements have been performed with a roll motion simulator at different frequencies between 0.3 and 1.0 Hz, to monitor the interface pressure change behavior of the seat-subject body. Temporal changes in body pressure in terms of the magnitude and the representative locations, and the time delay in pressure change at different regions of the seat are identified to be useful parameters for describing the subject's responses and with the subjective test results.
2015-06-15
Technical Paper
2015-01-2276
Zhengyu Liu, Donald Wozniak, Manfred Koberstein, Curtis Jones, Jan Xu, Suhas Venkatappa
Refrigerant flow-induced gurgling noise is perceived in automotive refrigerant systems which equipped with variable displacement compressors. In this study, the condition of the gurgling generation is investigated in vehicle level and the fundamental root cause is identified as the two-phase refrigerant flow entering the TXV. By conducting literature review, the acoustic characteristics of the flow patterns and the parameters affecting the flow regimes in horizontal and vertical tubes are summarized, and then the gurgling mechanism is explained as that the intermittent flow is developed at the evaporator inlet. In the end, the improved and feasible design for avoiding the intermittent flow (slug, plug or churn flow) or minimizing its formation is proposed and verified in refrigerant sub-system (RSS) level. Finally, the guidelines for the attenuation and suppression of the gurgle are provided.
2015-06-15
Technical Paper
2015-01-2275
Manfred Koberstein, Zhengyu Liu, Curtis Jones, Suhas Venkatappa
In the thermal expansion valve (TXV) refrigerant system, transient high-pitched whistle at 6.18 kHz is often perceived following air-conditioning (A/C) compressor engagements when driving at higher vehicle speed or during vehicle acceleration, especially when system equipped with the high-efficiency compressor or variable displacement compressor. The objectives of this paper are to conduct the noise source identification, investigate the key factors affecting the whistle excitation, and understand the mechanism of the whistle generation. The mechanism is hypothesized that the whistle is generated from the flow/acoustic excitation of the turbulent flow past the shallow cavity, reinforced by the acoustic/structural coupling between the tube structural and the transverse acoustic modes, and then transmitted to evaporator. To verify the mechanism, the transverse acoustic mode frequency is calculated and it is coincided to the one from measurement.
2015-06-15
Technical Paper
2015-01-2304
Hiroko Tada
In order to achieve a good balance between quietness in the vehicle interior cavity and lighter vehicle weight, it is necessary to study and optimize the specifications of the sound-proof packages. And, this optimization study is advisably done in the early stage of the vehicle development. For challenging to this antinomic, the process for improving automotive interior quietness (as related to air-borne noise above 400 Hz, considered the high-frequency range), with setting the marketability targets, the vehicle body acoustical performances and the parts specifications, was established. With conventional methods, it is challenging to disseminate the relationship between the overall vehicle performance and the performance of individual parts directly. Moreover, without new methods, it is also challenging to propose detailed specifications for the optimal sound-proof packages directly.
2015-06-15
Technical Paper
2015-01-2302
Yuksel Gur, Jian Pan, David Wagner
Light weighting of vehicle panels enclosing vehicle cabin causes NVH degradation since engine, road, and wind noise acoustic sources propagate to the vehicle interior through these panels. In order to reduce this NVH degradation, there is a need to develop new sound package materials and designs for use in lightweight vehicles. In this paper, we will focus on the use of SEA (Statistical Energy Analysis Tool) as a CAE design tool to develop sound packages for use in lightweight vehicle design to recover NVH deficiencies due to sheet metal light weighting actions. Statistical Energy Analysis results for vehicle level as well as dash and floor subsystem levels will be presented and SEA prediction capability for the sound package development for vehicle design will be discussed.
2015-06-15
Technical Paper
2015-01-2347
James A. Mynderse, Alexander Sandstrom, Zhaohui Sun
Mechanical engineering students at Lawrence Technological University (Lawrence Tech) must complete a capstone project, some of which are industry-sponsored projects (ISPs). American Axle & Manufacturing Inc. (AAM) partnered with LTU to provide a senior design experience in NVH through a proposed improvement to the AAM driveline dynamometer. AAM proposed that students design, develop, and fabricate a decoupling mechanism that minimizes the vibration disturbances transmitted from the driver shaft to the driven shaft. This work describes the LTU-AAM partnership, the design problem and the completed decoupler mechanism with experimental validation. The AAM driveline dynamometer provides immense value for experimental validation of product NVH performances. It has been intensively used to evaluate product design robustness in terms of build variations, mileage accumulation, and temperature sensitivity.
2015-06-15
Technical Paper
2015-01-2346
Balakumar Swaminathan
From a facility perspective, engine test cells are rarely evaluated for their vibration levels in their functional configuration. When complicated dynamic systems such as an internal combustion engine and a dynamometer are coupled together using driveshafts and coupling components, the overall system behavior is significantly different from that of the individual sub-systems. This paper details an instance where system level experimental testing and finite element analysis methods were used to mitigate high vibration levels in an engine test cell. Modal and operational test data were taken to establish baseline vibration levels at a diesel engine test cell during commissioning. Measurements were taken on all major sub-systems such as the engine assembly, dynamometer assembly, intermediate driveshaft bearing pedestal and driveshaft components.
2015-06-15
Technical Paper
2015-01-2362
Todd Tousignant, Kiran Govindswamy, Mark Stickler, Ming-Ran Lee
The increasing trend toward electric and hybrid-electric vehicles (HEVs) has created unique challenges for NVH development and refinement. Traditionally, characterization of in-vehicle powertrain noise and vibration has been assessed through standard operating conditions such as fixed gear engine speed sweeps at varied loads. Given the multiple modes of operation which typically exist for HEVs, character-ization and source-path analysis of these vehicles can be more complicated than conventional vehicles. In-vehicle NVH assessment of an HEV powertrain requires testing under multiple operating conditions for identification and characterization of the various issues which may be experienced by the driver. Gener-ally, it is necessary to assess issues related to IC engine operation and electric motor operation (running simultaneously with and independent of the IC engine), under both motoring and regeneration conditions.
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