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Viewing 1 to 30 of 23975
2017-07-10
Technical Paper
2017-28-1921
Jyotirmoy Barman
Engine down speeding is rapidly picking up momentum in the many segment of world market. Numerous engines down speeding packages from OEM have been tailored to take advantage of the increased efficiencies associated with engine down speeding. Running at a lower rpm provides numerous advantages. The most obvious of these is reduced fuel consumption, since the engine can spend more time running within its optimum efficiency range. By down speeding, the engine is made to run at low speeds and with high torques. For the same power the engine is operated at higher specific load (BMEP) which results in higher efficiency and reduced fuel consumption (BSFC). The reasons for increased fuel efficiency are reduced engine friction due to low piston speeds, reduced relative heat transfer and increased thermodynamic efficiency.
2017-06-05
Technical Paper
2017-01-1908
Rong Guo, Jun Gao, Xiao-kang Wei, Zhao-ming Wu, Shao-kang Zhang
Abstract The statement of the engine shake problem is presented through comparing the quarter vehicle models with the rigid-connected and flexible-connected powertrain which is supported on the body by a rubber mount. Then the model is extended by replacing the rubber mount as a hydraulic engine mount (HEM) with regard to the inertia and resistance of the fluid within the inertia track. Based on these, a full vehicle model with 14 degree of freedoms (DOFs) is proposed to calculate the engine shake, which consists of 6 of the powertrain, 1 of the fluid within the inertia track of the HEM, 3 of the car body and 4 of the unsprung mass. Simulation analysis based on the proposed model is implemented, through which the conclusion is drawn that the HEM has great influence on the body and seat track response subjected to front wheel inputs, compared with the rubber mount.
2017-06-05
Journal Article
2017-01-1774
Fabio Luis Marques dos Santos, Tristan Enault, Jan Deleener, Tom Van Houcke
Abstract The increasing pressure on fuel economy has brought car manufacturers to implement solutions that improve vehicle efficiency, such as downsized engines, cylinder deactivation and advanced torque lock-up strategies. However, these solutions have a major drawback in terms of noise and vibration comfort. Downsized engines and lock-up strategies lead to the use of the engine at lower RPMs, and the reduced number of cylinders generates higher torque irregularities. Since the torque generated by the engine is transferred through flexible elements (clutch, torsional damper, gearbox, transmission, tire), these also impact the energy that is transferred to the vehicle body and perceived by the driver. This phenomenon leads to low frequency behavior, for instance booming noise and vibration. This paper presents a combined test and CAE modelling approach (1D/3D) to reverse engineer a vehicle equipped with a CPVA (centrifugal pendulum vibration absorber).
2017-06-05
Technical Paper
2017-01-1783
Chris Todter, Olivier Robin, Paul Bremner, Christophe Marchetto, Alain Berry
Abstract Surface pressure measurements using microphone arrays are still challenging, especially in an automotive context with cruising speeds around Mach 0.1. The separated turbulent boundary layer excitation and the side mirror wake flow generate both acoustic and aerodynamic components, which have wavenumbers that differ by a factor of approximately 10. This calls for high spatial resolution measurements to fully resolve the wavenumber-frequency spectrum. In a previous publication [1], the authors reported a micro-electro-mechanical (MEMS) surface microphone array that successfully used wavenumber analysis to quantify acoustic versus turbulence loading. It was shown that the measured surface pressure at each microphone could be strongly influenced by self-noise induced by the microphone “packaging”, which can be attenuated with a suitable windscreen.
2017-06-05
Technical Paper
2017-01-1800
Robert White
Abstract Several analytical tools exist for estimating a driveshaft’s critical speed, from simple elementary beam theory to sophisticated FEA models. Ultimately, nothing is better than a test, because no one will argue with the outcome from a well-designed measurement. Impact response measurements are easy, but they tend to over predict the critical speed. A test which sweeps the shaft speed up until failure is telling, but the speed causing failure is strongly dependent on even small amounts of variation in rotor unbalance. Waterfall plots of shaft displacement measurements offer the best indication of critical speed, however sometimes the resonance isn’t unmistakable or multiple resonances exist, making the critical speed unclear. A method less susceptible to system variation is offered here, fitting shaft orbit measurements to the theoretical single degree of freedom equation.
2017-06-05
Technical Paper
2017-01-1803
John Van Baren
Abstract The accumulated damage that a product experiences in the field due to the variety of vibration stresses placed upon it will eventually cause failures in the product. The failure modes resulting from these dynamic stresses can be replicated in the laboratory and correlated to end use environment to validate target reliability requirements. This presentation addresses three fundamental questions about developing accelerated random vibration stress tests.
2017-06-05
Technical Paper
2017-01-1805
Krzysztof Prażnowski, Jaroslaw Mamala
Abstract The vibrations of the sprung mass of a passenger car, traveling along a road surface, are random. They also form its main source but there are besides other factors to consider. The resulting force ratio is overlapped by other phenomena occurring at the interface of the pneumatic tire with the road surface, such as non-uniformity of tires, shape deformations and imbalances. The resulting additional inertia force acts on the kinematic force that was previously induced on the car body. The vibrations of the sprung mass of the car body at the time can be considered as a potential source of diagnostic information, but getting insight their direct identification is difficult. Moreover, the basic identification is complicated because of the forces induced due to the random interference from road roughness. In such a case, the ratio defined as SNR assumes negative values.
2017-06-05
Technical Paper
2017-01-1851
Taewook Yoo, Ronald W. Gerdes, Seungkyu Lee, Daniel Stanley, Thomas Herdtle, Georg Eichhorn
Abstract Several methods for evaluating damping material performance are commonly used, such as Oberst beam test, power injection method and the long bar test. Among these test methods, the Oberst beam test method has been widely used in the automotive industry and elsewhere as a standard method, allowing for slight bar dimension differences. However, questions have arisen as to whether Oberst test results reflect real applications. Therefore, the long bar test method has been introduced and used in the aerospace industry for some time. In addition to the larger size bar in the long bar test, there are a few differences between Oberst (cantilever) and long bar test (center-driven) methods. In this paper, the differences between Oberst and long bar test methods were explored both experimentally and numerically using finite element analysis plus an analytical method. Furthermore, guidelines for a long bar test method are provided.
2017-06-05
Technical Paper
2017-01-1863
Bhaskar Avutapalli, Mayuresh Pathak, Shalini Solipuram, Ken Buczek, Aaron Lock
Abstract Road noise and speech intelligibility are becoming ever more important, irrespective of the vehicle size, due to vehicle refinement as well as connectivity with mobile communication equipment. With better aerodynamic designs, development of refined powertrains, and a tectonic shift from I.C. engine to electric motors, road noise and wind noise will become more apparent to the customer and hence will become a priority for automakers to refine their vehicles. This paper describes the efforts undertaken to identify the road noise paths and develop countermeasures for a compact SUV vehicle. A hybrid test/CAE approach was followed to improve road noise performance of this vehicle. This effort involved developing tire CAE models from physical hardware and creating synthesized road-load input from data taken on roads.
2017-06-05
Technical Paper
2017-01-1857
Joshua R. Goossens, William Mars, Guy Smith, Paul Heil, Scott Braddock, Jeanette Pilarski
Abstract Fatigue life prediction of elastomer NVH suspension products has become an operating norm for OEMs and suppliers during the product quoting process and subsequent technical reviews. This paper reviews a critical plane analysis based fatigue simulation methodology for a front lower control arm. Filled natural rubber behaviors were measured and defined for the analysis, including: stress-strain, fatigue crack growth, strain crystallization, fatigue threshold and initial crack precursor size. A series of four distinct single and dual axis bench durability tests were derived from OEM block cycle specifications, and run to end-of-life as determined via a stiffness loss criterion. The tested parts were then sectioned in order to compare developed failure modes with predicted locations of crack initiation. In all cases, failure mode was accurately predicted by the simulation, and predicted fatigue life preceded actual end-of-life by not more than a factor of 1.4 in life.
2017-06-05
Technical Paper
2017-01-1881
Charles Moritz, Satyajeet Deshpande
Abstract As part of the update process to SAE J1637, Laboratory Measurement of the Composite Vibration Damping Properties of Materials on a Supporting Steel Bar, the Acoustical Materials Committee commissioned a round robin study to determine the current laboratory-to-laboratory variation, and to better understand best practices for composite loss factor measurements. Guidance within the current standard from a previous round robin study indicates a coefficient of variation of 35% for laboratory-to-laboratory measurements. It was hoped that current instrumentation and test practices would yield lower variability. Over the course of 2 years, 8 laboratories tested 4 bars, three damped steel bars and one bare steel bar. These bars were tested at -20°C, -5°C, 10°C, 25°C, 40°C, and 55°C. The damping materials were intentionally selected to provide low damping, moderate damping, and high damping as difficulties in determining the composite loss increase with increased damping.
2017-06-05
Technical Paper
2017-01-1896
Richard A. Kolano, Darren J. Brown
Abstract A large reverberation room of approximately 310 m3 (11,000 ft3) used in the air conditioning, heating and refrigeration industry, was in need of improvements to meet the updated requirements of the American Heating and Refrigeration Institute (AHRI) Standard 220. In addition, it was desired to extend the measurement qualification of the room down to the 63 Hz octave band. The initial qualification test results showed that the room did not qualify for the extended low frequency range and also had some irregularities in the 100 Hz third octave band. This paper reports the results of a three-part investigation to correct reverberation room response irregularities in the 100 Hz third octave band, to establish performance that qualifies relative to the most recent standard, and to determine and integrate the means by which its qualification could be extended down to the frequency bands of 50, 63, and 80Hz.
2017-06-05
Technical Paper
2017-01-1886
Siwen Zhang, Jian Pang, Jun Zhang, Zhuangzhuang Ma, Xiaoxuan Zhang, Congguang Liu, Lihui Deng
Abstract A subjective evaluation method for the air-borne sound insulation of vehicle body in reverberation room is developed and the correlation between the subjective preference and objective noise reduction level (NRL) is investigated in this paper. The stationary vehicle's interior noise is recorded by using a digital artificial head under a given white noise excitation in the reverberation room, which demonstrates more credible than those in traditional road test methods. The recorded noises of six different vehicles are replayed and evaluated subjectively by 22 appraisers in a sound quality room. The paired comparison scoring method is employed and the check and statistic methods for the subjective scores are introduced. The subjective preference is introduced and calculated by the statistics and normalization of the effective scores, which can indicate an overall preference ranking of all the six vehicles numerically.
2017-05-26
WIP Standard
ARP6807
The intent of the SAE Recommended Practice (ARP) is to provide process for users to identify the part number of AS7928 terminal lugs installed in civilian or military applications, although can be used to identify terminals that have not been stored correctly. Thie ARP is subject to change to keep pace with experience and technical advances of AS7928 terminals. A current set of tables are provided to list and identify current AS7928 terminal lug configurations per the associated specification detail sheet and terminal lug configuration. Specific configuration details, graphic, size and marking information for each individual terminal lug is provided to assist the product user with accurate selection for replacement or identification.
CURRENT
2017-05-26
Standard
AS21925D
SCOPE IS UNAVAILABLE.
CURRENT
2017-05-25
Standard
AS20708/131B
Scope is unavailable.
CURRENT
2017-05-25
Standard
AS39029/90B
No scope available.
2017-05-25
WIP Standard
ARP1107C
This recommended practice covers the fixed structure, or independent energy absorbing system affixed to the airframe to afford protection to the control surfaces, engine and other portions during ground handling, take-off and landing.
2017-05-25
WIP Standard
J1113/27
1.1 Vehicle electrical/electronic systems may be affected when immersed in an electromagnetic field generated by sources such as radio and TV broadcast stations, radar and communication sites, mobile transmitters, cellular phones, etc. The reverberation method is used to evaluate the immunity of electronic devices in the frequency range of 500 MHz to 2.0 GHz, with possible extensions to 200 MHz and 10 GHz, depending upon chamber size and construction. Optional pulse modulation testing at HIRF (High Intensity Radiated Fields) test levels, based upon currently known environmental threats, has been added to this revision of the standard. This document addresses the Mode Stir (Continuous Stirring) Reverberation testing method which has been successfully utilized as a design and production stage development tool for many years.
CURRENT
2017-05-25
Standard
AIR805D
The purpose of this information report is to present the factors that affect the design and development of aircraft jet blast windshield rain removal systems. Rain removal system design will generally be unique to specific aircraft. Design of these systems typically requires a preliminary design for the system based on available empirical data to be followed with a laboratory development program and a flight test validation program. Published windshield rain removal performance test data is available only for limited windshield configurations.
CURRENT
2017-05-25
Standard
AS1043G
SCOPE IS UNAVAILABLE.
2017-05-24
WIP Standard
J2087
This SAE Standard provides test procedures, requirements, and guidelines for a daytime running light (DRL) function.
2017-05-23
WIP Standard
AS85598
This document defines the requirements for spherical, radial-journal, conical and thrust bearings which are of laminated elastomeric construction. These bearings are for use in an environment having a temperature spectrum within a maximum ambient temperature range of -65 degrees F to +160 degrees F while reacting oscillating loads and motions.
2017-05-23
WIP Standard
AS4270A
This document establishes techniques for validating that a mission store comples with the interface requirements delineated in MIL-STD-1760.
2017-05-23
WIP Standard
AS4764A
This document establishes techniques for validating that an aircraft station complies with the interface requirements delineated in MIL-STD-1760.
2017-05-22
WIP Standard
AIR6540
The scope of this report is to capture the fundamental principles of selecting a wire size for an aerospace application using the method prescribed in SAE AS50881 standard. Also, provided in this report are additional calculations to ensure the wire selection will adequately perform in a particular design function including meeting environment constraints. Some of the calculations in this report have been simplified to demonstrate the process for validating the wire size selections for a particular design application. More precise calculations should be investigated and evaluated to ensure proper assessment of each individual calculation in this report.
CURRENT
2017-05-22
Standard
AS39029/91B
SCOPE IS UNAVAILABLE.
CURRENT
2017-05-19
Standard
AMS2355M
This specification covers quality assurance sampling and testing procedures used to determine conformance to applicable specification requirements of wrought aluminum alloy and wrought magnesium alloy mill products (except forging stock), and includes quality assurance and testing procedures for rolled, forged, and flash welded rings (see 8.3). Requirements are specified in inch/pound units.
2017-05-18
Article
PCB Piezotronics, Inc.’s family of miniature triaxial ICP accelerometers, Models 356A43, 356A44 and 356A45, are small (0.4 x 0.4 x 0.75 in/10.2 x 10.2 x 19.05 mm), lightweight (4.2 g/0.15 oz) and TEDS (Transducer Electronic Data Sheets) IEEE 1451.4 enabled.
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