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Viewing 91 to 120 of 8727
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.
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
2014-01-2514
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.
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
2014-01-2512
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
2014-01-2513
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
2014-01-2517
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.
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
2014-01-2518
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.
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.
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.
2014-09-26
Article
The task facing calibrators is not getting any easier. “The complexity of calibration exploded exponentially when the Tier 4 emissions regulations were introduced,” explained Paolo Di Martino, Business Unit Director for Diesel Systems for IAV North America.
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.
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.
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.
2014-08-04
Article
The SAB 32 shield connection clip from Conta-Clip provides a quick, simple connection when cables require shielding from interference.
2014-08-04
Article
The R&S SMW200A high-end vector signal generator from Rohde & Schwarz supports frequencies up to 20 GHz.
2014-08-04
Article
Sonoscan’s AW322 200 automated system for ultrasonic inspection of MEMS wafers images and identifies internal gap-type defects down to 5µm in size.
2014-08-04
Article
The Model XLUS88 subminiature, bidirectional tension/compression load cell from tecsis LP operates from 150 g to 1000 lb.
2014-07-30
Article
The Electric Power Research Institute has announced a collaboration with 8 automakers and 15 utilities to develop and demonstrate an open grid integration platform for plug-in electric vehicles (PEVs).
2014-07-29
Article
To develop an electric powertrain with a minimum noise level and minimized whining it is necessary to have accurate CAE simulation and precise criteria to assess whining noise.
Viewing 91 to 120 of 8727

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