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Showing papers in "Journal of Tribology-transactions of The Asme in 2017"









Journal ArticleDOI
TL;DR: In this paper, the authors used the elastoplastic Jackson-Green rough surface contact model to quantify the contact forces using real and measurable surface and material parameters to simulate impact phenomena in a flexibly mounted stator (FMS) mechanical face seal designed to operate in a noncontacting regime.
Abstract: Noncontacting mechanical face seals are often described as unpredictable machine elements, gaining this moniker from numerous instances of premature and unexpected failure. Machine faults such as misalignment or imbalance exacerbate seal vibration, leading to undesirable and unforeseen contact between the seal faces. A hypothesis explaining the high probability of failure in noncontacting mechanical face seals is this undesired seal face contact. However, research supporting this hypothesis is heuristic and experiential and lacks the rigor provided by robust simulation incorporating contact into the seal dynamics. Here, recent developments in modeling rotor–stator rub using rough surface contact are employed to simulate impact phenomena in a flexibly mounted stator (FMS) mechanical face seal designed to operate in a noncontacting regime. Specifically, the elastoplastic Jackson–Green rough surface contact model is used to quantify the contact forces using real and measurable surface and material parameters. This method also ensures that the seal face clearance remains positive, thus allowing one to calculate fluid-film forces. The seal equations of motion are simulated to indicate several modes of contacting operation, where contact is identified using waveforms, frequency spectra, and contact force calculations. Interestingly, and for the first time, certain parameters generating contact are shown to induce aperiodic mechanical face seal vibration, which is a useful machine vibration monitoring symptom. Also for the first time, this work analytically shows a mechanism where severe contact precipitates seal failure, which was previously known only through intuition and/or experience. The utility of seal face contact diagnostics is discussed along with directions for future work. [DOI: 10.1115/1.4033366]

32 citations















Journal ArticleDOI
TL;DR: In this article, the effects of particle loading and particle size on tribological properties of the particulate composites were investigated, and the average size of biochar particles obtained through pulverizing using ball-mill varied from 510nm to 45nm while milling for a duration ranging from 6h to 30h.
Abstract: In this research work, pulverized biochar obtained by the pyrolysis of rice husk is used as particulate reinforcement in unsaturated polyester matrix. The effects of the particle loading and particle size on tribological properties of the particulate composites were investigated. The average size of biochar particles obtained through pulverizing using ball-mill varied from 510nm to 45nm while milling for a duration ranging from 6h to 30h. The particle loading in the composite was varied from 0.5wt% to 2.5wt%. It was observed that the particle size and particle content played a vital role in the tribological properties of the composites. The specific wear rate of the specimen having particle loading of 2.5wt% with 45nm particle size exhibited a decrease of 56.36% upon comparing with the specific wear rate of cured pure resin. The coefficient of friction of the same sample decreased by 6.42% when compared to that of a cured pure resin. The biochar particles were subjected to XRD, FT-IR and AFM analysis for characterization. Morphological studies were performed on the worn surfaces by SEM and Optical Microscopy.