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2014-09-30
Technical Paper
2014-01-2317
Rahul Ramola, G Senthilkumar, P Kannan, Muralidharan Chennakrishnan
Abstract The demand for comfort level in commercial vehicles is steadily increasing. Hence, fine-tuned performance parameters and attributes are required to fulfill the expectations from these vehicles. Refinement of noise and vibration without affecting performances of sub-systems and components has become extremely challenging with increasing customer requirements. This paper presents an approach to identify and reduce the high level whistling noise that was perceived in the passenger compartment while the vehicle was accelerated above 50 kmph. Interior noise measurements in static engine run-up condition reveal that the whistling noise is of specific order. Since, whistling noise is related to aerodynamic response of components, engine cooling fan, turbo charger, alternators and compressors were suspected. Using order tracking and near field measurements, HVAC alternator was confirmed as the main cause for whistling noise. Noise measurements confirmed that orders related to alternator cooling fan became dominant above 50 kmph.
2014-09-30
Technical Paper
2014-01-2318
Masahiro Akei, Takayuki Koizumi, Nobutaka Tsujiuchi, Takayuki Yamauchi
Abstract This paper describes an identification of a sound source model for a diesel engine installed on an agricultural machine by Inverse-Numerical Acoustic analysis (INA), and the applicability of the identified sound source model. INA is a method to identify surface vibrations from surrounding sound pressures. This method is applicable for a complicated-shaped sound source like an engine. In order to confirm the accuracy of the identified sound source model, the surface vibrations of the engine are compared with the measured results. Moreover, in the condition of the simulated engine room, the surrounding sound pressure levels of the engine are predicted using the sound source model and the boundary element method (BEM). For the verification of the prediction accuracy, the surrounding sound pressures of the engine are measured using the testing device which simulated actual engine room, namely an enclosure. As a result, the sound source model of the diesel engine is identified accurately using the INA.
2014-09-30
Technical Paper
2014-01-2315
John Anderson
Abstract This paper describes the development and testing of a Dynamic Vibration Absorber to reduce frame beaming vibration in a highway tractor. Frame beaming occurs when the first vertical bending mode of the frame is excited by road or wheel-end inputs. It is primarily a problem for driver comfort. Up until now, few options were available to resolve this problem. The paper will review the phenomenon, design factors affecting a vehicle's sensitivity to frame beaming, and the principles of Dynamic Vibration Absorbers (AKA Tuned Mass Dampers). Finally, the paper will describe simulation and testing that led to the development of an effective vibration absorber as a field fix.
2014-09-30
Technical Paper
2014-01-2314
John Stuart, Stefano Cassara, Brendan Chan, Nicholas Augustyniak
Wobble and shimmy vibrations are commonly observed in commercial highway vehicles with solid-beam front axles. These vibrations are typically self-excited and manifest themselves as sustained oscillations about the kingpin and axle tramp. A study was initiated to investigate and quantify wobble and shimmy behaviors, with a primary focus on wobble. A cross functional team including test and simulation engineers evaluated a vehicle exhibiting these behaviors. The team developed an ADAMS model to reproduce the behaviors and developed a DOE to quantify the impact of variables and combinations of variables. The evaluation demonstrated that dynamic imbalance in the rotating masses is a primary source of excitation. Wheel run-out, caster angle, tire brand, tire wear and tire inflation are also significant sources. Future studies will use these findings to mitigate the concern.
2014-09-28
Technical Paper
2014-01-2482
Meechai Sriwiboon, Nipon Tiempan, Kritsana Kaewlob, Seong Kwan Rhee
The influence of processing conditions on Low-Copper NAO disc pads were investigated as part of an effort to develop Low-Copper disc pad formulations as this kind of information is not readily available in open literature. Processing conditions as well as formulation modifications are found to influence friction, pad wear, disc wear and brake squeal. Low-Copper disc pads for pick-up trucks, equivalent to an OE pad, are developed. It is also found that brake squeal measured during the SAE J2522 (AK Master) Performance testing is related to the combined total wear rate of the disc plus the inner/outer pads or the disc wear rate alone, and that there is a threshold wear rate, above which brake squeal increases rapidly.
2014-09-28
Technical Paper
2014-01-2491
SeongJoo Lee, JooSeong Jeong, ShinWook Kim, ShinWan Kim, Seong Rhee
A previous investigation showed that minor variations in alloying elements in gray cast iron disc contributed to measurable differences in friction and disc wear. This investigation was undertaken to find out if and how the increased friction and disc wear might affect brake squeal. The SAE J2522 and J2521 dynamometer procedures as well as an OEM noise dynamometer procedure and a chassis dynamometer noise procedure were used to find out if a correlation between disc wear and brake squeal could be discovered. In all cases, as the wear rate of a disc increases under a given set of test conditions, disc material transfer to the pad surface increases, which results in increased friction and brake squeal. Also a good method to detect disc variability (disc to disc, within a disc) is discussed.
2014-09-28
Technical Paper
2014-01-2493
Juan Carlos Martinez Laurent, Adrian Jordan, Francisco Canales
Abstract The brake system and components are essential active safety systems for users of motor vehicles, one common NVH phenomenon known as Brake Disc Thermal Coning creates a perception of poor braking system performance. Although Brake Disc Thermal Coning does not deteriorate the braking distance or the vehicle performance, is a concern for the customer who identifies any undesired vibration as a potential performance loss resulting in complaints and warranty claims. In order to increase the quality, and reliability of the products, Automotive OEMs have created processes and tests, today incorporating the ones based in computational solutions, to identify, prevent and correct potential issues before its present in the final product. As computer technologies like Computer Aided Design (CAD), Computer Aided Engineering (CAE) and Computer Aided Manufacturing (CAM) have become more robust, and PC power clusters have increased the complexity of the problems resolution and decreasing the solver processing time, OEMs are moving forward from the road, to the lab and today to CAE.
2014-09-28
Technical Paper
2014-01-2510
Jung Hoon Woo, Jeongkyu Kim, Kwang Yun Kim, Daekyung Ko
Abstract Creep groan noise occurs in a just moving vehicle by the simultaneous application of torque to the wheel and the gradual release of brake pressure in-vehicle. It is the low frequency noise giving the driver a very uncomfortable feeling. It is caused by the stick-sleep phenomenon at the lining and disc interface. Recently, the field claim of low frequency creep groan has increased. There are a lot of efforts to improve creep groan noise by means of modification of lining material. In this paper, Transfer path of creep groan noise was analyzed through ODS and TPA. Additionally the correlation between Source (Brake torque variation, Brake vibration) and Creep Groan Sound level was discussed. Finally countermeasure to Creep Groan noise was suggested.
2014-09-28
Technical Paper
2014-01-2518
Diego Masotti, Ney Ferreira, Patric Neis, Ademir Menetrier, Luciano Matozo, Paulo Varante
Abstract Creep groan is a low-frequency (20-300Hz) self-excited brake vibration caused by stick-slip phenomena at the friction interface observed at very low vehicle speed. The creep groan propensity of friction materials is closely related with the difference (Δμ) between the static (μs) and the kinetic (μk) coefficients of friction. In this study, a NAO brake pad material was used as a base formulation and the abrasives tested were commercial grade of black iron oxide, chromite, zirconium oxide, magnesium oxide and aluminum oxide. Experimental results were obtained by testing seven different friction material formulations, in which the type of abrasives or its hardness or its particle size was changed in order to explore the impact of these variables on the stick-slip occurrence. A laboratory-scale tribometer was used to investigate the influence of different types of abrasives and their physical properties in the stick-slip. The results showed that abrasive particle size and hardness significantly affect the propensity of stick slip.
2014-09-28
Technical Paper
2014-01-2515
Jin kuk Park, Hyun Bum Jung, Min Gyu Han, Nam ill Jeon
Abstract Prediction of noise and vibration of a gear train is important to achieve a competitive design. Objective of this paper is to develop a dynamic simulation model for vibration analysis and a synthesis process to predict vehicle interior noise using TPA (Transfer Path Analysis). The hybrid gear model is developed to simulate the stiffness of teeth and meshing characteristics in a gear pair. It is modeled by using the teeth stiffness map which is following real contact characteristics of a gear pair. The teeth stiffness is obtained by structural analysis. The multi-body model is composed of flexible bodies, shafts and nonlinear bearings. Input forces at the mounting point (input point) of the gear train are calculated by accelerations from dynamic analysis under real operating conditions. Calculated forces are used to synthesize a vehicle interior noise. Predicted noise is compared with experiment data.
2014-09-28
Technical Paper
2014-01-2516
Katsuhiro Uchiyama, Yuji Shishido
Abstract Last year, we presented the “spring - mass model” FEA simulation from stick-slip phenomenon standpoint for improvement of “creep groan”. “Creep groan” is one of representative groan of brake system for automobile and it is clarified by µ vs velocity (µ−V) property of friction material. This time, we will present our study for reduction of creep groan by pad shape parameter (chamfer and slot) with “advanced” spring - mass model” FEA simulation which used actual pad shape as mass model. In addition, this paper was revised based on oral presentation which we presented at SAE 2013.
2014-09-28
Technical Paper
2014-01-2513
Taeho Jung, Jeongkyu Kim
Abstract Rust accumulated on disc surfaces causes brake judder and grind noise. This paper deals with grind noise(wire brush brake noise) in vehicles which is a low frequency vibration and broadband noise problem at 100∼1kHz that appears in low vehicle speed. Recently, the customer complaints have increased for grind and creep groan noise more than squeal noise. Low frequency brake noise is a combined effect of brake and suspension systems working with each other. The noise transfer path is also important. Experimental results are confirmed through ODS, Modal, TPA and 3D acoustic camera for noise transmission path. Finally, reduction methods of grind noise are presented.
2014-09-28
Technical Paper
2014-01-2514
Prashant Mahale, Aziz Bohari, Raajha M P
Abstract Brake noise is an emerging concern in Indian Auto-industry; with brake squeal being the most evident form of brake NVH. Squeal noise generation attributes to many parameters including kinematics of braking parts during pressure application, structural dynamic behavior which in turn depends on coupling at resonant frequencies of different parts of a brake assembly, material of brake parts, operating clearances in the mating parts etc. The genesis of brake squeal lies in the generation of unstable frictional forces during braking event. These frictional forces induce uncontrolled amplification of brake parts vibration, which in turn tend to produce perceivable sound or noise. The magnitude this vibration induced squeal depends on co-efficient of friction, braking pressure, speed and temperature of friction material. It is known from typical squeal evaluations on dynamometer that at different temperatures of friction, the ability/ occurrence, of squeal is different, typically in the range of 50°C to 200°C.
2014-09-28
Technical Paper
2014-01-2511
Nils Gräbner, Merten Tiedemann, Utz Von Wagner, Norbert Hoffmann
Abstract Industry and academia agree that brake squeal is a nonlinear phenomenon. Consequently, using solely linear finite-element (FE) models and assessing the tendency of a brake system to squeal exclusively on the stability of the trivial solution is not appropriate. However, the latter approach - in the brake community known as complex eigenvalue analysis (CEA) - is extensively used in industry. Until now, nonlinear simulation approaches considering existence and stability of periodic solutions are mostly limited to minimal models. Among the variety of reasons for this the complexity of large-scale nonlinear models as well as the identification of nonlinear material and system parameters are crucial. This contribution discusses the relevance of nonlinearities in friction brake noise, vibration, harshness (NVH) and presents a novel simulation approach for brake squeal. On the basis of experimental results it is pointed out that the consideration of nonlinearities in simulation as well as new methods for numerical studies are necessary to cope with the system-inherent phenomena.
2014-09-28
Technical Paper
2014-01-2512
Hidetoshi Shimizu, Yasunori Oura, Tatsuya Suzuki, Yoshinori Sano
Abstract SAE J2521 noise tests are conducted to examine the impact of shim and grease on brake squeal generation. The impact of adhesive (bonded) shim, clip-on shim and grease for noise generation are examined. Low frequency squeal is eliminated by the application of grease on both adhesive (bonded) shims and clip-on shims. The role of shim and grease for reducing brake squeal is discussed. Adhesive (bonded) shims were found to be effective for high frequency squeal (pad bending mode) by increasing damping. Grease is effective for low frequency squeal (pad rigid mode). The mechanism to eliminate low frequency squeal by the application of grease is investigated. Friction between the shim and caliper piston/finger is reduced. Pads contact directly to the anchor bracket. As a result the contact stiffness is increased. The mechanism is confirmed by experiments.
2014-09-28
Technical Paper
2014-01-2522
Tobias Schramm, Georg Peter Ostermeyer
Abstract There are few principal excitation mechanisms that brake system NVH simulations are based on, especially the high frequency squeal simulations. These mechanisms can be described by some simple mechanical models that exhibit excitation or self-excitation effects induced by friction [1, 2]. These models use very simple friction laws of Coulomb type, described by a friction coefficient that is either a constant or simple functions of some state variables, taking into account a Stribeck characteristic. Measurements from the AK-Master or SAE J2521, however, show that the friction coefficient is not a simple function of some state variables, describing a steady state behavior of friction. In the past several years, material dependent descriptions of the frictional brake interface have started attracting attention [3]. These aspects are greatly influenced by the tribological effects at the frictional interface, which can be characterized by typical wear patterns. To get a better understanding of the friction mechanisms between the brake pad and the disk, the topography of the disk must be measured using in-situ nondestructive methods, which must be very fast because of the size of the data set and also highly accurate to attain, for example, the wear properties of ceramic disks.
2014-09-28
Technical Paper
2014-01-2520
Qiang Wang, Gang Qi, Guangrong Zhang, Xinyu Pu
Abstract A brake durability experimental method is proposed to simulate a brake durability vehicle road test. Brake judder and noise often occur in brake durability road testing. Brake judder is difficult to address because of its many potential causes, such as assembly run out, component stiffness, lining characteristics, thermal coning/hot spot/thermal instability and corrosion. There are currently several test procedures to predict brake thermal roughness and pad cleaning corrosion performance for preventing brake judder. Brake durability vehicle road testing is performed to check brake NVH and wear; examples include the Mojacar test in Spain and the Huangshan test in China. Brake energy intensity and road vibration are the significant factors that cause brake rotor thickness variation, which generates brake judder in public road testing. This study is focused on brake pad wear depending on brake energy intensity and brake rotor temperature to simulate brake durability road testing and brake rotor thickness variation (RTV) generation induced by wear.
2014-09-28
Technical Paper
2014-01-2517
Kun Diao, Lijun Zhang, Dejian Meng
Abstract Disc brake squeal has always been a great challenge to the automotive industry. Based on the pin-on-disc system, a series of frictional squeal bench tests are carried out, which show significant time-varying characteristics on occurrence, sound pressure and frequency of frictional squeal. To investigate the generation mechanism of time-varying characteristics of frictional squeal, a four-degree-of-freedom (4DOF) lumped parameter model considering the time-varying tangential contact stiffness, the normal contact stiffness and the friction coefficient is established in this paper. Through both the system stability analysis and the transient response analysis, the time-varying frictional squeal is predicted successfully, and the generation mechanism and the key impact factors are also investigated in depth. The simulation results show that the time-varying characteristics of frictional squeal are influenced by the frictional contact characteristics of the friction pair, including tangential contact stiffness, normal contact stiffness and friction coefficient.
2014-09-24
Article
The use of quenched and tempered steels for dumper bodies reduces weight and fuel consumption while increasing payload capacity and wear life.
2014-09-22
Article
Internal combustion engines are poised for dramatic breakthroughs in improving efficiency with lower emissions, due in part to low-temperature combustion regimes. Such regimes show great efficiency and emissions potential, but they present optimization and control challenges.
2014-09-18
Standard
J1166_201409
This SAE Standard sets forth the procedures to be used in measuring sounds levels and determining the time weighted sound level at the operator's station(s) of specified off-road self-propelled work machines. This document applies to the following work machines which have operator stations as specified in SAE J1116: • Crawler Loader • Grader • Log Skidder • Wheel Loader • Crawler Tractor with Dozer • Pipelayer • Dumper • Wheel Tractor with Dozer • Trencher • Tractor Scraper • Backhoe • Sweeper • Roller/Compactor • Hydraulic Excavator • Pad Foot Wheel Compactor with Dozer • Excavator and Wheel Feller-Buncher The instrumentation requirements and specific work cycles for these machines are described. The method used to calculate the time weighted average sound level at the operator station(s) is specified for Leq(5), or optional exchange rates, during continuous operation in a work cycle representing continuous medium to heavy work. The work cycles provide a repeatable reproduceable means to uniformly measure working machines against a “yard stick.
2014-09-17
Standard
J994_201409
The scope of this SAE Standard is the definition of the functional, environmental, and life cycle test requirements for electrically operated backup alarm devices primarily intended for use on off-road, self propelled work machines as defined by SAE J1116 (limited to categories of 1) construction, and 2) general purpose industrial). This purpose of this document is to define a set of performance requirements for backup alarms, independent of machine usage. The laboratory tests defined in this document are intended to provide a uniform and repeatable means of verifying whether or nor a test alarm meets the stated requirements. For on-machine requirements and test procedures, refer to SAE J 1446.
2014-09-08
Article
Additional $35 million will fund the company’s unique research center an additional five years, concentrating on a ‘safe transition’ to future of automated and connected vehicle technologies.
2014-08-18
Article
Material laws and orientation information are coupled in a single finite element analysis to predict the performance of the hybrid composite beam under a dynamic three point bending load.
2014-08-18
Article
LC411-USBH low-profile compression load cells from Omega enable 1000 readings per second and feature a USB output to connect directly to a computer.
2014-08-13
Article
Model 3340 G-Logger three-channel, portable data acquisition system from Silicon Designs, Inc. (SDI) offers powerful Fast Fourier Transform (FFT) analysis and display, as well as real-time acceleration and GPS data collection and viewing, all within the same compact package.
2014-08-13
Standard
J184_201408
Various SAE vehicle sound level measurement procedures require use of a sound level meter which meets the Type 1 or Type 2 requirements of ANSI S1.4-1983 (see 2.1.1.1), or an alternative system which can be proved to provide equivalent test data. The purpose of this SAE Recommended Practice is to provide a procedure for determining if a sound data acquisition system (SDAS) has electro-acoustical performance equivalent to such a meter. By assuring equivalent performance of the test instrumentation, the equivalence of test data is assured. Two general configurations of sound data acquisition systems will be encompassed (see Figure 1). The first configuration consists of instrument sections which perform as a sound level meter. The second configuration is a system which records data for later processing. The intent of this document is to establish guidelines which permit the test engineer to insure equivalence of sound data acquisition systems to a sound level meter. It requires that the test engineer have a working knowledge of the characteristics of the sound data being measured.
2014-08-12
Article
AC17 test reporting begins in 2015. Initially it "gifts" applicable CAFE A/C efficiency credits, but leads to mandatory use. Industry also looks to reduce A/C-induced EV range loss from solar loading using films, glass, pre-ventilation.
2014-08-12
Article
Johnson Controls has opened a new crash test facility at its automotive seating headquarters in Plymouth, MI. One of the highlights of the facility is a Seattle Safety ServoSled that allows the automotive supplier to offer what it claims is the most accurate, standardized safety testing of seats globally through collaboration with its other testing facilities located in Burscheid, Germany; Changchun and Shanghai, China; and Yokohama, Japan.
2014-08-04
Article
HBM Inc.’s new industrial measurement amplifier enables users to make precise, dynamic measurements of raw and filtered torque, frequency, pulse, speed, and angle of rotation.
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