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Viewing 211 to 240 of 15854
2015-06-15
Journal Article
2015-01-2364
Xianpai Zeng, Jared Liette, Scott Noll, Rajendra Singh
Abstract The vibration isolation effectiveness of powertrain mount configurations is examined for electric vehicle application by considering the effect introduced by internal mount resonances. Unlike internal combustion engines where mounts are typically designed only for static support and low frequency dynamics, electric motors have higher excitation frequencies in a range where mount resonances often occur. The problem is first analytically formulated by considering a simple 3-dimensional powertrain system, and the vibration isolation effectiveness significantly deteriorates at the mount resonance(s). It is shown that by modifying the mount shape, the mount resonance(s) can be shifted while maintaining the same static rate, tuning the frequency away from any engine excitation or natural frequencies. Further, internal mount resonances are utilized to improve vibration isolation over a narrow frequency range, using non-identical mounts to split mount resonance peaks.
2015-06-15
Technical Paper
2015-01-2350
Jiantie Zhen, Scott Fredrickson
Abstract Off-highway machine mounting system isolation, especially the cab mounting system, significantly affects the operator comfort by providing damping to the harsh inputs and isolating the structure-borne energy from traveling into the cab. Mounting system isolation performance is decided not only by the isolation component, but also the mounting bracket structure, and should be treated as a system. This paper gives a review of how the mounting system isolates structural energy and the effect of the bracket structure stiffness to the mounting system isolation performance.
2015-06-15
Journal Article
2015-01-2178
Mohamed El Morsy, Gabriela Achtenova
Abstract When localized fault occurs in a bearing, the periodic impulsive feature of the vibration signal appears in time domain and the corresponding Bearing Characteristic Frequencies (BCFs) emerge in frequency domain. The common technique of Fast Fourier Transforms (FFT) and Envelope Detection (ED) are always used to identify faults occurring at the BCFs. In the early stage of bearing failures, the BCFs contain very little energy and are often overwhelmed by noise and higher-level macro-structural vibrations. In order to extract the weak fault information submerged in strong background noise of the gearbox vibration signal, an effective signal processing method would be necessary to remove such corrupting noise and interference. Optimal Morlet Wavelet Filter and Envelope Detection (ED) are applied in this paper.
2015-06-15
Journal Article
2015-01-2227
Scott Allen Noll, Benjamin Joodi, Jason Dreyer, Rajendra Singh
Abstract Elastomeric joints such as mounts and suspension bushings undergo broadband excitation and are often characterized through a cross-point dynamic stiffness measurement; yet, at frequencies above 100 Hz for many elastomeric components, the cross- and driving-point dynamic stiffness results significantly deviate. An illustrative example is developed where two different sized mounts, constructed of the same material and are shaped to achieve the same static stiffness behavior, exhibit drastically different dynamic behavior. Physical insight is provided through the development of a reduced order single-degree-of-freedom model where an internal resonance is explained. Next, a method to extract the parameters for the reduced order model from a detailed finite element bushing model is provided.
2015-06-15
Journal Article
2015-01-2229
Benjamin Joodi, Scott Allen Noll, Jason Dreyer, Rajendra Singh
Abstract Elastomeric joints are utilized in many automotive applications, and exhibit frequency and excitation amplitude dependent properties. Current methods commonly identify only the cross-point joint property using displacement excitation at stepped single frequencies. This process is often time consuming and is limited to measuring a single dynamic stiffness term of the joint stiffness matrix. This study focuses on developing tractable laboratory inverse experiments to identify frequency dependent stiffness matrices up to 1000 Hz. Direct measurements are performed on a commercial elastomer test system and an inverse experiment consisting of an elastic beam (with a square cross section) attached to a cylindrical elastomeric joint. Sources of error in the inverse methodology are thoroughly examined and explained through simulation which include ill-conditioning of matrices and the sensitivity to modeling error.
2015-06-12
Standard
AS28937A
SCOPE IS UNAVAILABLE.
2015-06-12
Standard
AMS5934/H1000
This specification covers a corrosion-resistant steel product in the solution and precipitation heat treated (H1000) condition 12 inches (305 mm) and under in nominal diameter, thickness or for hexagons, least distance between parallel sides (See 8.2).
2015-06-12
Standard
AS1301F
This SAE Aerospace Standard (AS) provides the essential minimum design, installation and removal standard for AS1299, AS1985, AS1986, AS4099, AS5368, and AS5986 adapters and is applicable when specified on engineering drawings or in procurement documents.
2015-06-09
Standard
AMS4944L
This specification covers a titanium alloy in the form of seamless tubing.
2015-06-08
Standard
AMS6915B
This specification covers a titanium alloy in the form of bars up through 6.000 inches (152.40 mm) inclusive, in nominal diameter or least distance between parallel sides, forgings of thickness up through 6.000 inches (152.40 mm), inclusive and stock for forging of any size.
2015-06-08
Standard
AMS6499A
This specification covers a premium aircraft-quality, low-alloy steel in the form of bars, forgings, mechanical tubing, and forging stock.
2015-06-05
Standard
AMSR83485/1A
The purpose of this specification sheet is to set up a standardized part numbering system for o-rings procured to MIL-R-83485 (USAF).
2015-06-04
Standard
AMS4465A
This specification covers an aluminum alloy in the form of sheet, clad on one side.
2015-06-04
WIP Standard
AS4726A
This specification establishes the requirements for self-locking nuts, wrenching type (i.e., hexagon, double hexagon, and spline drive), made of a corrosion and heat resistant steel of the type identified under the Unified Numbering System as UNS S66286. Classification: a. 220 ksi minimum tensile strength at room temperature and b. 850 degrees F maximum test temperature of parts. Primarily for use in aerospace propulsion systems in temperatures up to approximately 850 degrees were nuts are used with bolts capable of developing 220 ksi axial tensile strength at room temperature, and having UNJ thread form.
2015-06-04
WIP Standard
AS85049D
This specification covers connector accessories for use with electrical connectors, refer to 6.9.
2015-06-03
Standard
AMS4460A
This specification covers an aluminum alloy in the form of sheet, clad on two sides.
2015-06-02
Article
The WI system is in pilot development with a Bosch customer. Test results to date show a reduction of fuel consumption at high loads and low rpm (up to 4% improvement on the NEDC cycle); reduction or avoidance of fuel enrichment and lower exhaust-gas temperatures at high loads and high rpm, and improved torque.
2015-06-02
Standard
AS5728A
Scope is unavailable.
2015-06-02
Standard
AMS4236D
This specification covers an aluminum alloy in the form of sand, investment, permanent mold, and composite mold castings.
Viewing 211 to 240 of 15854

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