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Damping Behavior (damping + behavior)

Distribution by Scientific Domains

Polymers and Materials Science	71%

Selected Abstracts

Damping Behavior of the Free Liquid Interface Oscillation upon Step Reduction in Gravity

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003
M. Michaelis Dipl.-Ing.
Experiments were carried out to investigate the damping behavior of the reorientation of a free liquid interface in a right circular cylinder, partly filled with a liquid and suddenly exposed to a step reduction in gravity. The damping behavior basically depends on the Ohnesorge number and the static contact angle. This study shows the strong influence of the contact point for low static contact angles. [source]

Damping behavior of sandwich beam laminated with CIIR/petroleum resins blends by DMA measurement

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007
Cong Li
Abstract In this paper, we tried to develop a high damping material with chlorinated butyl rubber (CIIR) and petroleum resins. It was found that the addition of petroleum resins in CIIR could largely increase the loss factor and broaden the damping range. So a sandwich beam laminated with the new developed material was prepared, and the damping behavior of this sandwich beam was measured by dynamic mechanical analysis (DMA). The influence of temperature, frequency, thickness, and component of damping layer on the structural loss factor ,s determined by DMA was discussed based on a theoretical model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Elementary Mechanisms behind the High-Temperature Deformation Behavior of Lutetium-Doped Silicon Nitride

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2003
Giuseppe Pezzotti
Intergranular sliding and diffusive mechanisms behind the deformation behavior of a commercially available lutetium-doped silicon nitride were investigated and discussed. A method of locating and separating phenomena critical for mechanical relaxation at elevated temperatures was applied; the method was based on low-frequency forced-vibration damping measurements. The potentiality of lutetium addition for improving the deformation resistance of silicon nitride was clearly reflected in the high-temperature damping behavior of the investigated polycrystal. Softening of intergranular lutetium silicate phases located at multigrain junctions, which resulted in a grain-boundary sliding peak, occurred at remarkably high temperatures (>1725 K). This phenomenon, partly overlapping diffusional flow, was followed by further damping relaxation with the melting of the lutetium silicates. Subsequent grain growth was also detected at temperatures >2100 K. Torsional creep results, collected up to 2100 K, consistently proved the presence of a "locking" effect by lutetium silicates with the sliding of silicon nitride grain boundaries below 1873 K. [source]

Dynamic mechanical analysis of pineapple leaf/glass hybrid fiber reinforced polyester composites

POLYMER COMPOSITES, Issue 6 2010
L. Uma Devi
The dynamic mechanical properties of randomly oriented intimately mixed hybrid composites based on pineapple leaf fibers (PALF) and glass fibers (GF) in unsaturated polyester (PER) matrix were investigated. The PALFs have high-specific strength and improve the mechanical properties of the PER matrix. In this study, the volume ratio of the two fibers was varied by incorporating small amounts of GF such as PALF/GF, 90/10, 80/20, 70/30, and 50/50, keeping the total fiber loading constant at 40 wt%. The dynamic modulus of the compositeswas found to increase on GF addition. The intimately mixed (IM) hybrid composites with PALF/GF, 80/20 (0.2 Vf GF) showed highest E, values and least damping. Interestingly, the impact strength of the composites was minimum at this volume ratio. The composites with 0.46 Vf GF or PALF/GF (50/50) showed maximum damping behavior and highest impact strength. The results were compared with hybrid composites of different layering patterns such as GPG (GF skin and PALF core) and PGP (PALF skin and GF core). IM and GPG hybrid composites are found more effective than PGP. The activation energy values for the relaxation processes in different composites were calculated. The overall results showed that hybridization with GF enhanced the performance properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source]

New soybean oil-Styrene-Divinylbenzene thermosetting copolymers,IV.

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2002
Good damping properties
Abstract New polymeric materials have been prepared by the cationic copolymerization of regular soybean oil, low saturation soybean oil, i.e. LoSatSoy oil, or conjugated LoSatSoy oil with styrene and divinylbenzene, norbornadiene or dicyclopentadiene initiated by boron trifluoride diethyl etherate (BF3·OEt2) or related modified initiators. The effects of the stoichiometry, the type of soybean oil and the alkene comonomer on the damping behavior of the resulting polymers have been investigated. The damping properties have been quantitatively evaluated by the loss tangent maximum (tan ,)max, the temperature range ,T for efficient damping (tan ,,>,0.3), and the integrals of the linear tan , v. temperature curves (tan , area, TA). These bulk materials are composed primarily of soybean oil-styrene-divinylbenzene random copolymers with considerable variability in the backbone compositions. The good damping properties of the soybean oil polymers are presumably determined by the presence of fatty acid ester side groups directly attached to the polymer backbone and the segmental heterogeneities resulting from crosslinking. In general, crosslinking reduces the (tan ,)max and the TA values, but broadens the region of efficient damping (,T). Soybean oil polymeric materials with appropriate compositions and crosslink densities are capable of efficiently damping over a temperature region in excess of 110,°C and provide noise and vibration attenuation over broad temperature and frequency ranges. Copyright © 2002 John Wiley & Sons, Ltd. [source]