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SAE International Journal of Passenger Cars Mechanical Systems
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The Development of Terrain Pre-filtering Technique Based on Constraint Mode Tire Model

SAE International Journal of Passenger Cars - Mechanical Systems

Northern Arizona University-Eric neisen
Purdue University-Cannon Cheng
  • Journal Article
  • 2015-01-9113
Published 2015-09-01 by SAE International in United States
The vertical force generated from terrain-tire interaction has long been of interest for vehicle dynamic simulations and chassis development. To improve simulation efficiency while still providing reliable load prediction, a terrain pre-filtering technique using a constraint mode tire model is developed. The wheel is assumed to convey one quarter of the vehicle load constantly. At each location along the tire's path, the wheel center height is adjusted until the spindle load reaches the pre-designated load. The resultant vertical trajectory of the wheel center can be used as an equivalent terrain profile input to a simplified tire model. During iterative simulations, the filtered terrain profile, coupled with a simple point follower tire model is used to predict the spindle force. The same vehicle dynamic simulation system coupled with constraint mode tire model is built to generate reference forces. This terrain pre-filtering technique proves to improve the computational efficiency by three orders of magnitude with no statistically significant change in resultant load prediction.
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Current Status and Future Developments of ANC Systems

SAE International Journal of Passenger Cars - Mechanical Systems

Müller-BBM Active Sound Technology GmbH-Rolf Schirmacher
  • Journal Article
  • 2015-01-2223
Published 2015-06-15 by SAE International in United States
Active Noise Control (ANC) has long been seen as emerging technology. During recent years, however, it became popular in new vehicle and infotainment platforms within a broad range of OEMs. This paper summarizes the current status and lessons learned of production systems (as well as those entering production soon) and gives an outlook on how ANC and related technologies will integrate in future vehicles and audio/infotainment architectures.
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Perception of Diesel Engine Gear Rattle Noise

SAE International Journal of Passenger Cars - Mechanical Systems

Cummins Inc.-Frank Eberhardt
Purdue University-Brandon Sobecki, Patricia Davies, J Stuart Bolton
  • Journal Article
  • 2015-01-2333
Published 2015-06-15 by SAE International in United States
Component sound quality is an important factor in the design of competitive diesel engines. One component noise that causes complaints is the gear rattle that originates in the front-of-engine gear train which drives the fuel pump and other accessories. The rattle is caused by repeated tooth impacts resulting from fluctuations in differential torsional acceleration of the driving gears. These impacts generate a broadband, impulsive noise that is often perceived as annoying. In most previous work, the overall sound quality of diesel engines has been considered without specifically focusing on predicting the perception of gear rattle. Gear rattle level has been quantified based on angular acceleration measurements, but those measurements can be difficult to perform. Here, the emphasis was on developing a metric based on subjective testing of the perception of gear rattle. In the first part of the present work, a method to simulate gear rattle noise and incorporate it into a no-gear-rattle (baseline) recording was developed. That procedure enabled controlled variation of rattle within the total engine noise signal. The simulations were then used…
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Prediction of Interior Noise in a Sedan Due to Exterior Flow

SAE International Journal of Passenger Cars - Mechanical Systems

CD-adapco-Vincent Cotoni
Daimler AG-Alexander Schell
  • Journal Article
  • 2015-01-2331
Published 2015-06-15 by SAE International in United States
Aero-vibro-acoustic prediction of interior noise associated with exterior flow requires accurate predictions of both fluctuating surface pressures across the exterior of a vehicle and efficient models of the vibro-acoustic transmission of these surface pressures to the interior of a vehicle. The simulation strategy used in this paper combines both CFD and vibro-acoustic methods. An accurate excitation field (which accounts for both hydrodynamic and acoustic pressure fluctuations) is calculated with a hybrid CAA approach based on an incompressible unsteady flow field with an additional acoustic wave equation. To obtain the interior noise level at the driver's ears a vibro-acoustic model is used to calculate the response of the structure and interior cavities. The aero-vibro-acoustic simulation strategy is demonstrated for a Mercedes-Benz S-class and the predictions are compared to experimental wind tunnel measurements.
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Quantifying Hands-Free Call Quality in an Automobile

SAE International Journal of Passenger Cars - Mechanical Systems

Ford Motor Co.-Scott Amman, Francois Charette, Paul Nicastri, John Huber, Brigitte Richardson, Gint Puskorius, Yuksel Gur, Anthony Cooprider
  • Journal Article
  • 2015-01-2335
Published 2015-06-15 by SAE International in United States
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. It will be shown that a listening study of using 49 evaluators, indicated that the ETSI EG 202 396-3EG (VoIP Standard) for SMOS (Speech Mean Opinion Score) and NMOS (Noise Mean Opinion Score) correlates better than the ETSI TS 103 106 (Mobile Standard) for speech and noise ratings when quantifying the quality of…
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Door Closing Sound Quality Methodology - Airborne and Structural Path Contributions

SAE International Journal of Passenger Cars - Mechanical Systems

Siemens PLM Software-Saeed J. Siavoshani, Prasad Vesikar
  • Journal Article
  • 2015-01-2263
Published 2015-06-15 by SAE International in United States
The intent of this paper is to document comprehensive test-based approach to analyze the door-closing event and associated sound using structural and acoustic loads developed during the event. This study looks into the door-closing phenomenon from the structural interaction point of view between the door and the body of the vehicle. The study primarily focuses on distributing the door and body interaction as discrete multiple structural and acoustic phenomena. It also emphasizes on the structural and acoustic loads developed by the discretized interactions at the interfaces between the door and the body frame. These interfaces were treated to be the load paths from the door to the body. The equivalent structural and acoustic loads were calculated indirectly using the well-known Transfer Path Analysis (TPA) methodology for structural loads and the Acoustic Source Quantification (ASQ) methodology for acoustic loads. Considering the transient nature of the door-closing event, a time domain TPA methodology was also developed to study the loads being developed between the latch, the striker and the different interfaces of the door frame to the…
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Automotive Speech Intelligibility Measurements

SAE International Journal of Passenger Cars - Mechanical Systems

Toyota Technical Center USA Inc.-Gordon Ebbitt, Todd Remtema
  • Journal Article
  • 2015-01-2337
Published 2015-06-15 by SAE International in United States
Speech communication from the front seat to the rear seat in a passenger vehicle can be difficult. This is particularly true in a vehicle with an acoustically absorptive interior. Speech Transmission Index (STI) measurements can quantify the speech intelligibility, but they require specialized signal processing. The STI calculations can be simplified if it is assumed that reverberation and echoes play an insignificant role in an automobile. A simplification of a STI measurement is described that uses a stationary reference speech signal from a talker mannequin in the driver's seat to create a signal at the rear passenger positions. On-road noise measurements are used for the noise level and the calculated signal to noise ratio is used to calculate a simplified STI value that tracks closely to a full implementation of the STI method for sedans. In fact, this method is very similar to the techniques described in the Articulation Index (AI) and Speech Interference Index (SII) standards. Those standards provide for the use of a talker mannequin, though that is rarely done. The use of…
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Modeling of Active and Passive Damping Patches with Application to a Transmission Casing Cover

SAE International Journal of Passenger Cars - Mechanical Systems

Ohio State University-Joseph Plattenburg, Jason Dreyer, Rajendra Singh
  • Journal Article
  • 2015-01-2261
Published 2015-06-15 by SAE International in United States
Combined active and passive damping is a recent trend that can be an effective solution to challenging NVH problems, especially for lightweight vehicle components that demand advanced noise and vibration treatments. Compact patches are of particular interest due to their small size and cost, however, improved modeling techniques are needed at the design stage for such methods. This paper presents a refined modeling procedure for side-by-side active and passive damping patches applied to thin, plate-like, powertrain casing structures. As an example, a plate with fixed boundaries is modeled as this is representative of real-life transmission covers which often require damping treatments. The proposed model is then utilized to examine several cases of active and passive patch location, and vibration reduction is determined in terms of insertion loss for each case. Results are compared to an experiment with an actual transmission casing for validation, using piezoelectric active patches and constrained-layer passive patches with a viscoelastic core. Conclusions are drawn about patch size and location in terms of NVH reduction capability, and guidelines are suggested for the…
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Optimizing Body Panels for NVH Performance

SAE International Journal of Passenger Cars - Mechanical Systems

Chrysler India Automotive Pvt, Ltd.-Murali Balasubramanian, Ahmed Shaik
  • Journal Article
  • 2015-01-2265
Published 2015-06-15 by SAE International in United States
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. The main challenge for NVH engineers is to recover panel stiffness and mitigate the potentially increased air-borne as well as structure-borne noise transmissibility thru these lighter panels. This is achievable with a systematic approach to optimizing panel geometry and damping treatment upfront during the body structure development process while also incorporating innovative new light weight solutions for acoustic insulation.This paper describes generic FE based methods to virtually engineer body…
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Numerical Determination of Transfer Impedance for Perforates

SAE International Journal of Passenger Cars - Mechanical Systems

University of Kentucky-P. Wang, J. Li, T. W. Wu
  • Journal Article
  • 2015-01-2312
Published 2015-06-15 by SAE International in United States
A simplified method to model perforated tubes in mufflers is the equivalent transfer impedance approach. Various empirical formulas that consider the porosity, hole diameter, wall thickness, and flow type have been proposed to date. They normally work very well under the conditions that the formulas are intended for. However, there are situations that the empirical formulas may not be able to cover. In this paper, we propose a simple BEM-based numerical procedure to determine the transfer impedance from a small perforate sample, and then send the transfer impedance to the muffler BEM model for analysis purposes. Numerical results are verified in three test cases.
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