In recent years, the utilization of rotating parts, e.g., bearings and gears, has been continuously supporting the manufacturing line to produce a consistent output quality. Due to their critical ...role, the breakdown of these components might significantly impact the production rate. Prognosis, which is an approach that predicts the machine failure, has attracted significant interest in the last few decades. In this paper, the prognostic approaches are described briefly and advanced predictive analytics, namely a parsimonious network based on a fuzzy inference system (PANFIS), is proposed and tested for low speed slew bearing data. PANFIS differs itself from conventional prognostic approaches, supporting online lifelong prognostics without the requirement of a retraining or reconfiguration phase. The PANFIS method is applied to normal-to-failure bearing vibration data collected for 139 days to predict the time-domain features of vibration slew bearing signals. The performance of the proposed method is compared to some established methods, such as ANFIS, eTS, and Simp_eTS. From the results, it is suggested that PANFIS offers an outstanding performance compared to those methods.
This research aimed to determine whether accomplished surfers could accurately perceive how changes to surfboard fin design affected their surfing performance. Four different surfboard fins, ...including conventional, single-grooved, and double-grooved fins, were developed using computer-aided design combined with additive manufacturing (3D printing). We systematically installed these 3D-printed fins into instrumented surfboards, which six accomplished surfers rode on waves in the ocean in a random order while blinded to the fin condition. We quantified the surfers' wave-riding performance during each surfing bout using a sport-specific tracking device embedded in each instrumented surfboard. After each fin condition, the surfers rated their perceptions of the Drive, Feel, Hold, Speed, Stiffness, and Turnability they experienced while performing turns using a visual analogue scale. Relationships between the surfer's perceptions of the fins and their surfing performance data collected from the tracking devices were then examined. The results revealed that participants preferred the single-grooved fins for Speed and Feel, followed by double-grooved fins, commercially available fins, and conventional fins without grooves. Crucially, the surfers' perceptions of their performance matched the objective data from the embedded sensors. Our findings demonstrate that accomplished surfers can perceive how changes to surfboard fins influence their surfing performance.
Smoothness of thin metallic coated strip produced in continuous galvanizing lines is influenced by fluctuations of the impinging wiping pressure. In this paper, vortex dynamics e.g. vortex production ...frequency and mixing of jet opposing shear layer vortices; and impinging pressure were numerically studied by Large Eddy Simulation (LES). The effects of jet nozzle width, d, and operational parameters (nozzle to strip distance, H, and mean jet velocity, Uo) were investigated. Vortex production rate is almost linearly correlated to Uo and mixing of shear layer vortices occurs when H/d ≥ 6. Dominant frequencies of impinging pressure fluctuation are significantly different between the two possible phenomena of i) Mixing of opposing shear layer vortices prior to jet impingement on the strip, or ii) No mixing of opposing shear layer vortices prior to jet impingement. The impinging pressure of a jet characterised by mixing of vortices is predominantly composed of frequencies lower than 10 kHz with the most significant components at less than 1 kHz. In contrast, for a jet with non-mixing of vortices, the impinging pressure fluctuations are comprised of frequencies greater than 10 kHz and the dominant frequency is approximately one half the vortex production frequency. Utilising existing model results for the coating thickness response to pressure and shear stress fluctuations12) the anticipated degree of coating thickness sensitivity to the mixing and non-mixing impinging jet cases of the present work has been elucidated. It is shown that a mixed vortices jet is most likely to cause surface ripples in the coating.
A molecular dynamics simulation of confined n-alkanes has been conducted to investigate the effects of the chain length of lubricant molecule and normal load on friction and asperity contact. The ...density distribution and surface coverage of lubricant atoms were calculated. The simulation results indicate that longer chain n-alkanes can provide more atoms for the mono-layer in the asperity contact interface than shorter ones, which, as a result, significantly reduce the friction force when the asperity contact occurs. C64-alkanes molecules can form a mono-layer of lubricant to avoid direct asperity contact at pressures up to 1000MPa.
Impinging planar jets are a widely used means of removing excess drag-out coating material from steel strip in order to control the final thickness of the applied coating. A wide range of possible ...coating defects are known to occur for this process, many of which are suspected to have their origin in the spatio-temporal characteristics of the air jets. It is therefore of interest to improve understanding of the link between the unsteady flow behaviour inherent to impinging jets and the evolution of the coating free surface produced by the gas-wiping process. In this paper, the coating response, characterised by the amplitude and frequency of the coating thickness fluctuation, throughout both the active region of the gas-wiping jets and the region immediately downstream, is investigated using a numerical model. The pressure and shear stress profiles acting on the coating surface along the strip are imposed as time-varying inputs such that for both the pressure and shear the vertical location of the entire profile undergoes sinusoidal oscillation parallel to the strip. A range of amplitude-frequency combinations for the vertical oscillation of the profiles are employed to assess the combined effect of these parameters on the coating response. Additionally, the strip speed is a varied parameter. Both the magnitude of the coating thickness fluctuation and the corresponding shape of the coating surface profile along the strip are found to be dependent on the strip speed and the oscillation amplitude and frequency of the vertical location of the pressure and shear stress profiles.
In this paper, a high temperature pin-on-disc configuration was used to simulate the contact established between a high-speed steel (HSS) work roll and a hot strip material in hot rolling, in which ...the pin represented the HSS roll and the disc represented a strip steel. The pin surfaces were oxidised due to the heat transfer from the disc while they were in contact. This work focused on the contact behaviour of the oxide scale in the roll bite during hot rolling while the testing temperature was close to the rolling temperature, the Hertzian pressure was similar to the contact pressure and the sliding speed was close to those in the roll bite. The coefficient of friction during the tests was monitored and recorded in-situ. It was found that the evolution of the coefficient of friction could be divided into three stages. Associated with the evolution of the coefficient of friction, the morphologies and micro-structures on the surface of pin were characterised by means of SEM, FIB and TEM techniques to study the tribological behaviour of oxide scale in contacts. The results indicated that the wear mechanism of pin surface varies in different stages. At the stages I and II, the oxide scale on the pin surface is significantly deformed. At the stage III, which the coefficient of friction is stable, the wear mechanism is a mixture of adhesion, abrasion and oxidation. The oxide transfer from the mild carbon steel disc to HSS pin significantly contributed to the scale formed on the HSS pin surface.
The tribological tests of a ferritic stainless steel (FSS) 445 in contact with high-speed steel (HSS) were performed on a high-temperature pin-on-disc tribometer. Wear exhibited significant ...difference when the FSS 445 was oxidised with a Cr-rich oxide scale on the surface. The HSS pin displayed adhesive wear when there was no oxide scale on the stainless steel disc, and in the early stages, the coefficient of friction fluctuated significantly, but the level of wear changed as Cr
2
O
3
particles formed. The wear was then reduced, and the coefficient of friction remained stable. The Cr-rich oxide scale which formed on the stainless steel was able to stabilise the coefficient of friction, to reduce the wear rate and to help form a glazed layer on the HSS surface. The abrasive wear of the HSS pin took place at 850 °C, indicating that the hardness of the Cr-rich oxide scale increased as the temperature decreased.
In this study, a dual-phase Li4Ti5O12-TiO2 microrod was successfully prepared using a modified hydrothermal method and calcination process. The stoichiometry of LiOH as precursor was varied at mol ...ratio of 0.9, 1.1, and 1.3, to obtain the appropriate phase composition between TiO2 and Li4Ti5O12. Results show that TiO2 content has an important role in increasing the specific capacity of electrodes. The refinement of X-ray diffraction patterns by Rietveld analysis confirm that increasing the LiOH stoichiometry suppresses the TiO2 phase. In the scanning electron microscopy images, the microrod morphology was formed after calcination with diameter sizes ranging from 142.34 to 260.62 nm and microrod lengths ranging from 5.03–7.37 μm. The 0.9 LiOH sample shows a prominent electrochemical performance with the largest specific capacity of 162.72 mAh/g and 98.75% retention capacity achieved at a rate capability test of 1 C. This finding can be attributed to the appropriate amount of TiO2 that induced the smaller crystallite size, and lower charge transfer resistance, enhancing the lithium-ion insertion/extraction process and faster diffusion kinetics.
This paper presents an application of multivariate state estimation technique (MSET), sequential probability ratio test (SPRT) and kernel regression for low speed slew bearing condition monitoring ...and prognosis. The method is applied in two steps. Step (1) is the detection of the incipient slew bearing defect. In this step, combined MSET and SPRT is used with circular-domain kurtosis, time-domain kurtosis, wavelet decomposition (WD) kurtosis, empirical mode decomposition (EMD) kurtosis and the largest Lyapunov exponent (LLE) feature. Step (2) is the prediction of the selected features’ trends and the estimation of the remaining useful life (RUL) of the slew bearing. In this step, kernel regression is used with time-domain kurtosis, WD kurtosis and the LLE feature. The application of the method is demonstrated with laboratory slew bearing acceleration data.
Vegetable oil-in-water (VO/W) emulsions are bio-based metal working lubricants. The emulsions’ lubrication performance depends on the stability of oil droplets. In this paper, the oil droplets’ ...dispersion stability and lubrication of emulsions containing TiO2/SiO2 nanoparticles (NPs) as dispersant and lubrication agents have been investigated. Enhanced dispersion of NP-shielded oil droplets was found. Increasing the NPs’ mass fraction initially lowers the average size of NP-shielded droplets up to the saturation of the droplets’ surface with NPs at 0.5 wt % mass fraction. NPs also form NP agglomerates in emulsions, more so after the droplets’ surfaces have been saturated with NPs. There is an apparent minimum quantity of NPs (~0.5 wt %) required to ensure sustained dispersions of the droplets which is thought to be related to the oil concentration and the droplets’ total surface-area-to-volume ratio. Below the required quantity of NPs, partially shielded and fully shielded droplets coexist. The partially shielded droplets initially attract other droplets and undergo limited coalescence but retain their long-term stability. A small quantity of NPs improves the antiwear property of the lubricants. However, emulsions with NPs have slightly higher friction than the NP-free emulsion due to the reduced strength of the tribofilm. Despite the increased friction, the tribofilm formed in presence of NPs can easily be removed from the surface with water, indicating cleaner surfaces after the lubrication (i.e., less oil residue on the surfaces), which, for the sake of cleanliness, is favourable in many applications.
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