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2015-09-29
Technical Paper
2015-01-2854
Timothy Opperwall, Andrea Vacca
Hydraulic systems have an important role in both on and off-highway vehicles. Designing for improved noise performance of fluid power systems is an essential part of improving current systems and opening up new areas where fluid power can bring improvements in efficiency and performance. As the technology advances and spreads to lighter applications, the noise generation and propagation due to hydraulic components becomes a primary design concern. The present research includes development of acoustic radiation models for noise radiation from hydraulic pumps and motors. The need for new methods for identification of noise sources and transmission is evident in order to direct future modeling efforts. Discovering the key features of noise generation from both simulation and experimental techniques allows for improved techniques to improve the noise performance of fluid power components and systems.
2015-09-27
Technical Paper
2015-01-2690
Joo Sang Park
This paper introduce several practical cases to cure the squeal noise by investigating pad unstable behaviour and self-excited vibration, and propose frequency guide lines for better noise performance. These guide lines are very useful for designers especially at the initial design stage. By using historical DOE, practical frequency guide lines will be proposed to achieve better noise performance at the initial design stage by using historical database analysis. This study has some limitations that the guide lines are available for disc. It will be further study for other brake components. In conclusion, the practical guide lines for robust disc design will be proposed after analyzing a pad unstable behaviour and disc self-excited vibration during squeal by theoretical , numerical and experimental approach. Finally the guide lines is validated by statistical approach by reviewing historical DOE for various brake systems.
2015-09-27
Technical Paper
2015-01-2689
Katsuhiro Uchiyama, Yuji Shishido
Last year we presented the FEA simulation of  “spring - mass (Pad’s shape) model” from stick-slip phenomenon for improvement of creep groan. Creep groan is one of representative groan noise on automobile brake system.    As a result of parameter study with various pad shape (chamfer, slot, etc.…), we showed that brake pad with radial slot angle has a range which increases creep groan performance.   This year we would like to present our study for advantageous direction for reduction of creep groan which will focus on friction material Mu vs. Velocity (M-V) property, friction material physical properties and relative velocity between brake pads and rotor by advanced brake assembly FEM model which considers torsional stiffness of suspension.
2015-09-27
Technical Paper
2015-01-2684
Seongjoo Lee, ShinWook Kim, ShinWan Kim, Seong Rhee
A correlation between brake squeal and disc wear was reported previously. This investigation was undertaken to confirm the correlation and to characterize the disc wear particles transferred to the sliding surface of the NAO pad. It is found that the iron distribution on the pad is very non-uniform; at some locations, the iron concentration reaches the level of Low Steel Lomets (15-20wt%); and squealing brakes exhibit increased amounts of transferred disc wear particles on the pad surface. These transferred particles are found as small and flattened thin metallic sheets, which are different from relatively large “metal pick-up” pieces.
2015-09-27
Technical Paper
2015-01-2683
Sarah Chen, Steve Hoxie
Developing a quiet brake system has been a constant task for OEM as well as their brake suppliers. Squeal problems may taint the image of a car manufacturer and cause substantial revenue loss from warranty claims despite the fact that the brake remains fully functional and safe. As a major component in the brake system, the rotor plays significant role in brake noise performance. Because of the cost and damping property advantages, gray iron is still the most widely used material for brake rotor application. When pads/rotor coupling is looked at to minimize noise issues, however, most efforts have been on pads and insulators. Rotor specifications are rather general and the component is typically accepted based on grades defined by mechanical property minimum (mostly in G3000 SAE J431).
2015-09-27
Technical Paper
2015-01-2702
Chihoon Jo, Jaeseung Cheon, Jongsung Kim, Yongsik Kwon
The EMB converts the electric set values into clamping forces at the brakes through an independent motor control at each wheel. EMB systems are now being developed by automobile part suppliers. In particular, as the market share of electrically powered vehicles, such as hybrid electric vehicles, elctric vehicle and fuelcell elctric vehicle, has expanded, the EMB makes it possible to recuperate the braking energy in the overall control loop of the braking unit, even in electrically powered vehicles. However, in order to commercialize, the EMB has many problems such as production competitiveness, reliability and regulations. A new concept, the Hybrid Electro-Mechanical Brake(hEMB) is characterized by a dual piston structure linked by hydraulics inside of the caliper. It is possible to reduce motor, actuator size and backup system in emergency through amplification of dual piston.[1] The hEMB is composed of caliper system, dual piston, screw, BLAC type motor and actuator.
2015-09-27
Technical Paper
2015-01-2687
Aditya Kant Choudhary, Yogesh Mense, Saurabh Singh, Mahesh Shridhare
Brake noise is one of the common complaints and an irritant not just for the vehicle occupants but equally for the passers-by. Brake noise is actually vibration that is occurring at a frequency that is audible to the human ear. This occurrence of brake noise like brake squeal (>1 kHz) and groan (<1 kHz) is often very intense and can lead to number of customer complaints. During a brake noise event, vehicle basic structure and suspension system components are excited due to brake system vibration and result in a resonance that is perceived in the form of a noise. Proposed work discusses an experimental study that is carried out on a commercial vehicle for addressing customer complaints regarding disc brake squeal and groan noise. Based on the preliminary inputs, vehicle level study was carried out in order to simulate the problem and objectively capture its severity.
2015-09-27
Journal Article
2015-01-2678
Diego Adolfo Santamaria Razo, Johan Decrock, Ann Opsommer, Maarten Fabré, Fernao Persoon
Friction performance is the consequence of the interaction between rotor and friction material surfaces. In order to stop the car, kinetic energy has to be transformed into heat, plastic deformations, chemical reactions and wear debris (1). The latest generates the formation of the so called third body layer and its initiation, growth and degradation will generate the actual friction coefficient and wear (2). Third body layer is composed by a semi continuous layer formed by primary and secondary plateaus (3) and its chemical composition depends upon the combination of compounds present in the friction material formulation, rotor chemical composition and quality, environmental conditions and testing procedures (2). Nevertheless some raw materials seem to promote third body layer formation more than others. The main chemical composition of the plateaus are iron oxide –probably coming from the rotor- copper, carbon, silicon and calcium (3).
2015-09-27
Journal Article
2015-01-2682
Masaaki Nishiwaki, Ryutaro Misumi
High brake performance is required for vehicle safety. At the same time, mass reduction of brake system is also required for vehicle economic long run. Under these backgrounds, high friction coefficient pad materials come to be adopted for brake system. But it is well known that brake squeal is often caused by high friction coefficient pad materials. Therefore, brake squeal research is one of very important technical issues for vehicles design. Disc brake squeal is caused by small disturbance in dynamic unstable systems. Today, disc brake squeal can be simulated by FE Analysis in actual disc brake, but it is remained a technical issue of small disturbance, brake squeal trigger of friction force variation. Low-frequency disc brake squeal around 2 kHz can be caused by forced vibration during brake application, which is shown by N.Ishihara and me in references (1). This research suggests the trigger of disc brake squeal generation.
2015-09-27
Journal Article
2015-01-2691
Ju Young Kim, Jeongkyu Kim, Young Min Kim, Wontae Jeong, Hojoon Cho
In the brake system, unevenly distributed disc-pad contact pressure distribution during braking is not only a loss of braking power but also a main cause of system instability which lead to squeal noise. In this reason there has been various attempts to measure contact pressure distribution. In the brake industry, static pressure distribution is measured and utilized to guess actual pressure distribution. In this study new test method is designed to quantitatively measure dynamic contact pressure distribution between disc and pad in vehicle testing. Upon various driving conditions and shape of pad, characteristics of dynamic contact pressure distribution were analyzed. Based on those results, analytical model updated and found to better detect propensity of brake squeal.
2015-09-15
Technical Paper
2015-01-2435
Ramakrishnan Murthy
One major problem that any product (say Motor, engines etc) which converts electrical energy into a mechanical energy would have is resonance. It has tendency to damage any material when the products operating frequency matches the resonant frequency. The major consequences of this resonant frequency in Flight at run-time could be catostrophic. Generally it is a practice to avoid running at the resonant frequency. This is done as a fixed method where the systems are designed not to run on resonant frequency, i.e. a subsystem in a system is now being designed for that system alone which will not match the resonant frequency. But the same subsystem may not be suitable for some other system. Hence this requires multiple designs. However this idea is to make a design generic where any subsystem can be used in any system irrespective of its resonant frequency. The technique uses the PID algorithm. This method will be helpful is having a single design for different systems.
2015-09-15
Technical Paper
2015-01-2477
Alessandro Gardi, Roberto Sabatini
Abstract This paper presents the conceptual design of a new low-cost measurement system for the determination of pollutant concentrations associated with aircraft operations. The proposed system employs Light Detection and Ranging (LIDAR) and passive electro-optics equipment installed in two non-collocated components. The source component consists of a tuneable small-size and low-cost/weight LIDAR emitter, which can be installed either on airborne or ground-based autonomous vehicles, or in fixed surface installations. The sensor component includes a target surface calibrated for reflectance and passive electro-optics equipment calibrated for radiance, both installed on an adjustable support. The proposed bistatic system determines the column-averaged molecular and aerosol pollutant concentrations along the LIDAR beam by measuring the cumulative absorption and scattering phenomena along the optical slant range.
2015-09-15
Technical Paper
2015-01-2605
Jamnie Yazmín Achem Calahorra, Hilda E. Esparza Ponce, Patricia Zambrano Robledo, Facundo Almeraya Calderón, Citlalli Gaona Tiburcio
Abstract Thin films deposited by magnetron sputtering are review in terms of their potential and present uses in the aircraft industry. The aircraft alloys substrates were Ti-6Al-4V and Incoloy 800HT, using a target of yttrium stabilized zirconia (YSZ) with nominal composition of 8% Y2O3 (wt%) and the remainder of ZrO2. The chemical composition of the films was determined by X-ray energy dispersion (EDS). The electrochemical noise behavior show that the coatings decreased propagation of pitting, leading to a state of passivation or uniform corrosion, and also possess superior corrosion resistance over the individually substrates.
2015-09-06
Technical Paper
2015-24-2526
Borislav Klarin, Thomas Resch, Chiara Sessarego, Giorgio Spanu, Gianni Lamonaca
This paper presents a methodology for numerical investigation of a full flexible balancer drive together with engine and crank train under realistic operating conditions where shaft dynamics, gear contact and rattle impacts, gear root stresses and friction losses in bearings and gear interaction are taken into account and can be balanced against each other to achieve the design criteria. Gear rattle is driven by the speed fluctuation of the crank train, the resistance torque (mainly friction), shaft inertia and the backlash in the gears. The actual trend to engine downsizing and up-torqueing increases the severity to rattle as engines are running on higher combustion pressures. This increases torque and speed fluctuation, which makes the detailed investigation in this torque transfer even more demanding. A common method to reduce gear rattle is the usage of so-called scissors gears.
2015-09-06
Journal Article
2015-24-2462
Fabio Auriemma, Heiki Tiikoja
The acoustic impedance exhibited by a new type of element for noise control, the Micro-Grooved Elements (MGEs), has been widely investigated in this paper. The MGEs are typically composed of two overlying layers presenting macroscopic slots and a number of micro-grooves on one of the contact surfaces. The micro-grooves result in micro-channels as the layers are assembled to form the element. Similarly to Micro-Perforated Elements (MPEs), the MGEs have been proved to provide effective dissipation of acoustic energy by the means of viscous losses taking place in the micro-channels. However, in contrast to the MPEs, the MGEs use the grooves, instead of the holes, in which the air is forced to pass through. It results in more cost effective elements, which have been found to represent an adequate alternative for fibrous materials, typically present in silencer units.
2015-09-06
Journal Article
2015-24-2527
Daniela Siano, Giovanni Ferrara, Giulio Lenzi, Danilo D'Agostino, Andrea Fioravanti
In an Internal Combustion Engine, the design of the intake system is a very critical aspect since it affects both the engine power output and noise emissions at the intake side. In particular, downsized VVA engines typically produce higher gas-dynamic noise levels since, due to the intake line de-throttling at part-load, a less effective attenuation of the pressure waves is realized. In this work, the acoustic performance of the intake air filter of a commercial VVA engine is numerically and experimentally analyzed. In particular, a FEM model of the system is realized in order to compute the Transmission Loss (TL) parameter of the base device. The numerical analysis accounts of fluid-structure interaction, which gives the possibility to determine the effect of structure participation on the TL profile. Contemporarily, the experimental tests are performed on an acoustic test bench based on the multi-microphone technique for the evaluation of the acoustic parameters.
2015-08-20
WIP Standard
AS8034C
This SAE Aerospace Standard (AS) specifies minimum performance standards for all types of Electronic Displays and Electronic Display Systems that are intended for use in the flight deck by the flightcrew in all 14 CFR Part 23, 25, 27, and 29 aircraft. The requirements and recommendations in this document are intended to apply to all installed electronic displays and electronic display systems within the flight deck, regardless of intended function, criticality, or location within the flight deck, but may also be used for non-installed electronic displays. This document provides baseline requirements and recommendations (see section 2.3 for definitions of “shall” and “should”). This document primarily addresses hardware requirements, such as electrical, mechanical, optical, and environmental. It does not address system specific functions.
2015-08-11
Standard
J2629_201508
SAE developed this document and associated spreadsheets at the request of automobile manufacturers to help compare products from multiple suppliers using standard data presentation formats. This document includes several preferred formats for presenting acoustical data on materials, components, systems, or vehicles. These formats cover the range of acoustical tests commonly conducted in the automotive industry. These tests follow SAE and ASTM test practices as well as vehicle specific test methods. For each test, the details of samples and test conditions can be entered into an applicable electronic spreadsheet together with the acoustical results data. These data are then linked to standard graphical display(s) for each test. All manufacturers and suppliers in this industry are encouraged to present data and results in these formats.
2015-08-01
WIP Standard
ARP4462A
This recommended practice covers the procedures and method for establishing acceptance criteria when performing Barkhausen noise testing of surface-hardened steel components to detect grinding burns (metallurgical damage caused by over-heating) in bare or chromium-plated parts. Primarily for nondestructive testing of heat treated, high strength low-alloy steel parts which have been ground, in accordance with MIL-STD-866 or commercial standard, before or after chromium plating. This test method may be used as an independent test or to confirm grinding damage detected in accordance with AMS 2440 or MIL-STD-867 in bare or chromium plated components.
2015-06-29
WIP Standard
J1400
This SAE Recommended Practice presents a test procedure for determining the airborne sound barrier performance of materials and composite assemblies commonly installed in surface vehicles and marine products. This document is intended to provide a means of rank ordering barrier materials according to their sound transmission loss. At each test frequency the transmission loss (TL) is projected from the measured noise reduction of the test specimen using a correlation factor (CF). The respective CF for the test condition is determined as the differences between the measured noise reduction (MNR) of a homogeneous limp panel, such as lead, and its calculated field-incidence transmission loss. Latitude is permitted in certain test conditions that do not necessarily conform to all of the acoustical requirements of ASTM E 90.
2015-06-23
WIP Standard
J2889/1
This SAE Standard is derived from SAE J2805 and specifies an engineering method for measuring the sound emitted by M and N category road vehicles at standstill and low speed operating conditions.. The specifications reproduce the level of sound which is generated by the principal vehicle sound sources consistent with stationary and low speed vehicle operating conditions relevant for pedestrian safety. The method is designed to meet the requirements of simplicity as far as they are consistent with reproducibility of results under the operating conditions of the vehicle. The test method requires an acoustic environment which is only obtained in an extensive open space or in special designed indoor facilities replicating the conditions of an extensive open space. Such conditions usually exist during: Measurements of vehicles for regulatory certification. Measurements at the manufacturing stage. Measurements at official testing stations.
2015-06-15
Technical Paper
2015-01-2326
Denis Blanchet, Anton Golota
Abstract Recent developments in the prediction of the contribution of wind noise to the interior SPL have opened a realm of new possibilities. The main physical mechanisms related to noise generation within a turbulent flow and the vibro-acoustic transmission through the vehicle greenhouse is nowadays better understood. Several simulation methods such as CFD, FEM, BEM, FE/SEA Coupled and SEA can be coupled together to represent the physical phenomena involved. The main objective being to properly represent the convective and acoustic component within the turbulent flow to ensure proper computation of the wind noise contribution to the interior SPL of a vehicle.
2015-06-15
Technical Paper
2015-01-2308
Yitian Zhang, David W. Herrin
Abstract The two-load method is commonly applied to determine the transmission loss for a muffler especially if an impedance tube rig is used. Although one procedure and algorithm is detailed in ASTM E2611, the quality of the transmission loss curve is dependent on several factors that are not discussed in detail in the standard. In this paper, several practical concerns are investigated including (1) the number of channels used in the measurement, (2) the selection of the reference channel, and (3) the choice of data processing algorithm (transfer or scattering matrix). Results are compared for a simple expansion chamber first, then for mufflers of other types. Recommendations are made for obtaining smoother transmission loss curves for various measurement methods.
2015-06-15
Technical Paper
2015-01-2309
David Neihguk, M.L. Munjal, Abhinav Prasad
Abstract The bias flow in Concentric Tube Resonator (CTR) is a flow-induced phenomenon in which the pressure gradient along the radial direction is produced by the kinetic energy of the flow. As a result, the flow dynamics in CTR is characterized by bias flow into the annular cavity in the upstream and outflow from the annular cavity in the downstream of the flow. This is due to the change in direction of the radial component of the bias flow at a point called the point of recovery, as a consequence of mass conservation. The pressure drop of CTR is a complex function of the momentum flux and other geometric parameters such as porosity, open area ratio, discharge coefficient of the perforated holes, bias inflow, bias outflow, grazing flow and length. In this study, numerical experiments are conducted to obtain an empirical formula for the friction factor of perforated pipes which are extensively used in automotive mufflers.
2015-06-15
Technical Paper
2015-01-2301
Maxwell Hill, Dan Luo, Mark Moeller
Abstract 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 to 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
2015-01-2310
Edward Ray Green
Abstract The Sound Transmission Loss of automotive intake and exhaust components is commonly measured using the four microphone tube method per ASTM E2611 [1]. Often area adapters are used to match the component diameter to that of the tube apparatus. These area adapters affect the Sound Transmission Loss measurement, especially at very low frequencies. The use of the Transfer Matrix Technique to remove the effect of the area adapters is described. The improvements for step and cone area adapters are compared.
2015-06-15
Technical Paper
2015-01-2358
Rod Morris-Kirby, Evan Harry, Dirk Jaeger, Bernd Borgmann
Abstract Acoustic Diagnostic Network Algorithms (DNA) are experimental methods that extract airborne acoustic characteristics from a motor vehicle and decompose this information into a set of networks from which the source, path and receiver noise sources and paths can be determined. Unlike traditional transfer path analysis Acoustic DNA takes the problem into the fine detail. It answers questions such as what, where and how does a vehicle's acoustic systems need to be changed in order to achieve any given objective. This paper describes the fundamental methodology and features together with how it has been implemented into a computer program that has been used successfully in over 50 vehicle projects within the Authors Research and Development group on a wide range of motor vehicles.
2015-06-15
Technical Paper
2015-01-2351
Hongyu Shu, Shuang Luo, Li Wang
Abstract In order to measure the noise of auto shock absorbers, a test bench used to detect piston-rod vibration responses of shock absorbers and measuring analyzer named SANTS-I were developed. The vibration response data was detected by bench tests, which shows that there are high-frequency violent peaks on the sine curve of piston-rod oscillating with relative low frequency. In order to explain the interior work dynamic mechanism of shock absorbers, a schematic Micro-process Dynamic Model with 10 steps particularly divided extension and compression stroke in more detail, and dynamic differential equations for each step were presented and discussed. Furthermore, numerical simulation for the inner impacts interaction between piston and damping fluid of hydraulic shock absorber was realized by ADINA software, by the establishment of a gas-liquid two-phase finite element model.
2015-06-15
Technical Paper
2015-01-2367
David Lennström, Arne Nykänen
Abstract When it comes to the acoustic properties of electric cars, the powertrain noise differs dramatically compared to traditional vehicles with internal combustion engines. The low frequency firing orders, mechanical and combustion noise are exchanged with a more high frequency whining signature due to electromagnetic forces and gear meshing, lower in level but subject to annoyance. Previous studies have highlighted these differences and also investigated relevant perception criteria in terms of psycho-acoustic metrics. However, investigations of differences between different kinds of electric and hybrid electric cars are still rare. The purpose of this paper was to present the distribution of tonal components in today's hybrid/electric vehicles. More specifically, the number of prominent orders, their maximum levels and frequency separation were analyzed for the most critical driving conditions. The study is based upon measurements made on 13 electrified cars on the market.
2015-06-15
Technical Paper
2015-01-2365
Zhaohui Sun, Glen Steyer, Jason Ley
Abstract Alternative powertrains, in particular electric and plug-in hybrids, create a wide range of unique and challenging NVH (noise, vibration & harshness) issues in today's automotive industry. Among the emerging engineering challenges from these powertrains, their acoustic performances become more complicated, partially due to reduced ambient masking noise level and light weight structure. In addition, the move away from conventional displacement engines to electrical drive units (EDU) has created a new array of NVH concerns and dynamics, which are relatively unknown as compared to the aforementioned traditional setups. In this paper, an NVH optimization study will be presented, focusing on four distinct factors in electric drive unit gear mesh source generation and radiation: EDU housing and bearing dynamics, gear geometry, EDU shafting torsional dynamics, and EDU housing structure. The study involves intensive FEA modeling/analyses jointly with physical validation tests.
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