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A Non-Contact Technique for Vibration Measurement of Automotive Structures

Kettering University-Vanshaj Srivastava, Javad Baqersad
  • Technical Paper
  • 2019-01-1503
To be published on 2019-06-05 by SAE International in United States
The automotive and aerospace industries are increasingly using the light-weight material to improve the vehicle performance. However, using light-weight material can increase the airborne and structure-borne noise. A special attention needs to be paid in designing the structures and measuring their dynamics. Conventionally, the structure is excited using an impulse hammer or a mechanical shaker and the response is measured using uniaxial or multi-axial accelerometers to obtain the dynamics of the structure. However, using contact-based transducers can mass load the structure and provide data at a few discrete points. Hence, obtaining the true dynamics of the structure conventionally can be challenging. Thus, researchers and test engineers seek for non-contact measurement techniques that do not induce mass loading effects and provide full field response. In last decade, stereo-photogrammetry and three-dimensional digital image correlation have received special attention in collecting operating data for structural analysis. These non-contact optical techniques provide a wealth of distributed data over the entire structure. However, the stereo camera system is limited by its field of view of the cameras and can only…
 

A Computational Process to Effectively Design Seals for Better Wind Noise Performance

Exa Corporation-Robert Powell, Philippe Moron, Sivapalan Senthooran
Jaguar Land Rover-Nicholas Oettle
  • Technical Paper
  • 2019-01-1472
To be published on 2019-06-05 by SAE International in United States
Ability to assess noise transmitted through seals to cabin interiors early in the design process is very important for automotive manufacturers. When seal design is inadequate, noise transmitted can dominate the interior noise, making the wind noise performance of the vehicle unacceptable. This may cause launch delays costing a great deal of money and 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 OEMs, as the supplier must cover tool and redesign costs. Deliberate overdesign by adding multiple layers of seals everywhere reduces profit by raising part and manufacturing costs. 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 the first time. The current study presents a computational process that can be used to predict interior noise transmitted through seals early in…
 

System interactions affecting NVH performance of an Electric Vehicle drivetrain

Romax Technology Ltd-Melanie Michon, Robert Holehouse, Hisham Jafarali, Annabel Shahaj
  • Technical Paper
  • 2019-01-1545
To be published on 2019-06-05 by SAE International in United States
The paper will present an integrated approach to system NVH analysis, which gives an insight into the system response in an EV driveline due to electrical and mechanical excitations; namely gear transmission error, rotor mechanical imbalance, electrical machine torque ripple, and stator radial force shapes. The paper will address the fact that, as part of a practical design exercise, different subsystems and components may achieve design maturity at different times. It is therefore important to understand to what extent various drivetrain components may be considered in isolation, and at what point it becomes necessary to consider the interactions present in the full system. The paper will compare predicted NVH performance of a representative EV traction motor when different boundary conditions are considered; for example, when considering the motor in isolation, when being tested in a representative test setup, and when included in a representative drivetrain. For each configuration, the response to mechanical and electro-mechanical noise mechanisms will be assessed. In each case, the fidelity of simulation required to achieve an appropriate engineering insight will be…
 

Reducing vehicle interior NVH by means of locally resonant metamaterial patches on a rear shock tower

KU Leuven - DMMS lab, Flanders Make-Luca Sangiuliano, Claus Claeys, Elke Deckers PhD, Bert Pluymers, Wim Desmet PhD
MotionS lab, Flanders Make-Jasper De Smet
  • Technical Paper
  • 2019-01-1502
To be published on 2019-06-05 by SAE International in United States
Stringent regulations for CO2 emissions and noise pollution reduction demand lighter and improved NVH solutions in automotive industries. Designing light, compact and, at the same time, improved NVH solutions is often a challenge, as low noise and vibration levels often require heavy and bulky additions, especially to be effective in the low frequency regime. Recently, locally resonant metamaterials have emerged among the novel NVH solutions because of their performant NVH properties combined with lightweight and compact design. Thanks to stop band behavior, metamaterials beat the mass law, be it at least in some tunable frequency ranges. Previously the authors demonstrated how metamaterials can reduce the vibrations in a simplified shock tower upon shaker excitation. In this work, the authors apply the metamaterial concept on a real shock tower of a vehicle. As benchmark, a vehicle is chosen which has a 1.46 kg weight addition in the form of a lumped tuned vibration absorbers on each of the rear shock towers as NVH solution. It is shown that the metamaterial solution allows to achieve similar interior…
 

Preliminary Study of Perceived Vibration Quality for Human Hands

Bruel & Kjaer North America-Edward Green, Sophie Kaye
Kettering University-Jennifer M. Bastiaan
  • Technical Paper
  • 2019-01-1522
To be published on 2019-06-05 by SAE International in United States
A large body of knowledge exists regarding the effects of vibration on human beings; however, the emphasis is generally on the damaging effects of vibration. Very little information has been published regarding the effect of vibration on perceived consumer product quality. The perceived loudness of a product is quantified using the Fletcher-Munson equal loudness curves, but the equivalent curves for perceived vibration amplitude as a function of amplitude and frequency are not readily available. This "vibration quality" information would be valuable in the design and evaluation of many consumer products, including automobiles. Vibration information is used in the automobile design process where targets for steering wheel, seat track, and pedal vibration are common. For this purpose, the vibration information is considered proprietary and is generally applicable to a narrow frequency range. In this investigation, work paralleling the original Fletch-Munson study is presented. "Equal comfort curves" for vibration were measured and developed for hands grasping a bar. A paired-comparison test methodology was used to establish an equivalency of perceived vibration comfort for vibration in a wide…
 

Comparison of Measurement Methods for Evaluating Displacement of Commercial Vehicle Seats

CVG-James Haylett
Univ of Washington-Peter Johnson
  • Technical Paper
  • 2019-01-1481
To be published on 2019-06-05 by SAE International in United States
Vehicle seats and seat suspension have been evolving ever since the introduction of seats with built-in, integral suspensions. Measuring the relative displacements of the seat suspension may help better understand the magnitude and frequency of displacements the seat suspension and ultimately the occupant is exposed to. These displacement measurements may complement acceleration measurements and may provide additional information to help improve vehicle seat design. Displacement can be measured directly with lasers and potentiometers, but it would be less complicated if accelerometers, already being used to measure and characterize the vehicle and vehicle seat vibration, could be used to measure the displacement. Accelerometers can produce relatively accurate, correlated displacement results from well behaved, controlled, sinusoidal cyclical vibrations, but their utility for measuring real-world random vibration needs further evaluation and characterization. This paper will compare gold-standard methods for measuring vertical seat displacements directly to displacements measured and derived by double integrating the vertical accelerations from accelerometers. Actual field displacement, acceleration and GPS measurements were collected from vehicles as they travelled over different road types. In this paper…
 

Rapid Optimal Design of a Light Vehicle Hydraulic Brake System

Politecnico di Torino-Pier Giuseppe Anselma, Shirish Padmakar Patil, Giovanni Belingardi
  • Technical Paper
  • 2019-01-0831
To be published on 2019-04-02 by SAE International in United States
Designing automobile brake systems is generally complex and time consuming. Indeed, the brake system integrates several components and has to satisfy numerous conflicting government regulations. Due to these constraints, designing an optimal configuration is not easy. This paper consequently proposes a simple, intuitive and automated methodology that enables rapid optimal design of light vehicle hydraulic brake systems. Firstly, the system is modeled through cascaded analytical equations for each component. A large design space is then generated by varying the operational parameters of each component in its specific reasonable range. The system components under consideration include the brake pedal, the master cylinder, the vacuum-assisted booster, the brake line and the brake pistons. Successful system configurations are identified by implementing the requirements of the two most relevant safety homologation standards for light vehicle brake systems (US and EU legislations). Ergonomics constraints and the compensation for the fluid losses are then retained as further design requirements. Finally, the optimal design identification is carried out based on overall system braking performance and the cost. Particularly, optimal braking performance is…
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Investigation of the Acoustic Surface Power on a Cooling Fan Using the Mesh Morpher Optimizer

Advanced Safety & Energy Inc.-Mike Kheirallah
Ford Motor Company-Abdallah Hamieh
  • Technical Paper
  • 2019-01-0833
To be published on 2019-04-02 by SAE International in United States
A cooling fan is an essential device of the engine cooling system which is used to remove the heat generated inside the engine from the system. An essential element for successful fan designs is to evaluate the pressure over the fan blade since it can generate annoying noices, which have a negative impact on the fan’s performance and on the environment. Reducing the acoustic surface power will assist in building improved designs that comply with standards and regulations in achieving a more quiet environment. The usage of computational fluid dynamics (CFD), with support of mesh morphing, can provide simulation study for optimizing the shape of a fan blade to reduce the aeroacoustic effects. The investigation process will assist in examining and analyzing the acoustic performance of the prototype, impact of different parameters, and make a solid judgement about the model performance for improvement and optimization.This paper proposes a new strategy in evaluating the pressure distribution over a fan blade. CFD techniques and optimization methodology were applied to improve the acoustic surface power distribution over a…
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Modeling Fuel Tank Draining/Sloshing in a Typical Transiently Accelerating Vehicle using GT-SUITE for Reliable Tank Designing

Gamma Technologies LLC-Arpit Tiwari, Nils-Henning Framke
  • Technical Paper
  • 2019-01-1262
To be published on 2019-04-02 by SAE International in United States
Draining and fuel starvation prediction is of critical importance in designing and approving fuel tanks. Simulation of fluid dynamics to predict draining of a moving tank having multiple fuel compartments and multiple ports is, however, challenging. This is because the dynamics involve multiple fluids which follow distinct thermodynamics - compressible air at the top and nearly incompressible fuel below it. Moreover, for a typical vehicle accelerating transiently in a general trajectory (road profile), the surface angle keeps changing which leads to dynamic fuel covering/uncovering of interior as well as outlet ports. Simulation of these effects often requires 3D multiphase solution, which is computationally expensive especially when it is required to model additional fluid systems such as fuel pipes and jet pumps. We present fast and efficient modeling and simulation of tank draining using the 0D/1D framework of GT-SUITE. The flexibility and robustness of the inbuilt flow solver allows accurate solution of the associated multiphase flow dynamics. Furthermore, the software is geometrically flexible to capture the surface angle variations (sloshing) inside complicated 3D shaped tanks in…
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Numerical Analysis Using Fast RANS Simulations and Comparison with Experimental Measurements for Closed and Open Grille Realistic Car Models

Simerics Inc.-Sujan Dhar, Yu Jiang
  • Technical Paper
  • 2019-01-0655
To be published on 2019-04-02 by SAE International in United States
This paper details a comprehensive CFD study of all three variants of the DrivAer car geometries: Fastback, Notchback and Estate configurations. The most realistic geometry was chosen for each of the variants; with detailed underbody, wheels and mirrors. In addition to the closed-grille standard DrivAer models, the open-grille variant has also been simulated. Simulations are performed and compared with experiments both with and without ground simulation. Mesh generation was performed without surface alterations (e.g. wrapping) using a novel Binary-Tree automatic unstructured mesher. All simulations were performed using an enhanced k-ε RANS turbulence model within Simerics MP+. A consistent modeling methodology was developed that was rigorously applied to all variants of the DrivAer model and the simulations are shown to have consistently good agreement with experimental measurements. This demonstrates the potential of using such a methodology for several different types of vehicles during the design process.In addition to presenting the methodology and the results, a thorough review was conducted and comparisons are made with the existing body of literature on the DrivAer model: including both RANS…
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