Wear Position Research Articles

Effect of Sand Containing Conditions on Wear of Nano Ceramic Coating on Downhole Cyclone

Based on the discrete phase mode (DPM) in Computational Fluid Dynamic (CFD) software Fluent, the numerical simulation and experimental study on erosion wear properties of a new nano ceramic coating for downhole cyclone were carried out under sand containing conditions of the produced liquid. The results showed that the maximum wear position of nano ceramic coating in the spiral flow channel in downhole oil-water separator was in the range of azimuth 108°∼144°, and the coating wear rate increased with the increase of inlet flow velocity. When the particle size of sand phase was less than 0.3 mm, the wear rate of nano ceramic coating on cyclone was greatly affected by the particle size. The wear rate decreased with the increase of particle size. When the particle size of sand phase was larger than 0.3 mm, the wear rate of nano ceramic coating was less affected by the particle size. At the same time, the sand phase mass fraction was in the range of 0.1%∼3%. With the increase of sand content in the produced liquid, the wear rate of the cyclone coating increased gradually.

Effect of wear scar characteristics on the bearing capacity and fracture failure behavior of winding hoist wire rope

Surface wear is an inevitable damage of wire ropes used in winding hoist. It always reduces the service life of the wire rope and threatens the mine safety. The characteristics of the surface wear scar caused by sliding contact between ropes were discussed in a quantitative and qualitative method for this paper. A series of breaking tensile tests were carried out to investigate the effects of the wear characteristic parameters on the bearing capacity of the rope. Furthermore, the fracture failure behaviors of the rope with different wear scars were analyzed. Results show that the wear scar changes from distributing on one strand to evenly distributed on two adjacent strands as the sliding wear position changes from the strand peak to valley. When the wear region concentrates on one strand, the maximum wear depth increases from approximately 0.46 mm to approximately 0.64 mm with the increase of wear area. Broken wires seriously affect the elongation and breaking force of the rope. The maximum breaking force is approximately 42 KN and the maximum local elongation is approximately 1.5 mm under the condition of broken wires. Additionally, the external wires of the strand are easier to fracture caused by torsion and tension together. Furthermore, the shear lip and the fibre region on the fracture surface of the wires become not very obvious with the increase of the wear scar parameters. • The distribution of the wear scar is different with the change of sliding wear position. • The wear depth and wear area affect variation of force-elongation curves at different degrees. • The effect of the wire breaking on the elongation and breaking force of ropes most obviously. • The fracture of the outer wires was caused by torsion and tension together. • The plastic deformation and bearing capacity of ropes decrease with wear parameters.

Numerical study on wear evolution and mechanical behavior of steel wires based on semi-analytical method

Based on the elastic contact theory and Archard's theory of wear, a mathematical model for wear evolution and mechanical behavior of steel wires in perpendicularly crossed configuration is established in the present study. The mathematical model is solved with a progressive solution process, in which a semi-analytical method (SAM) is adopted to realize the precise and fast evaluation of contact pressure, deformation and internal stress of the wires. The results show that both the wear and mechanical performances depend on the number of wear cycles and the position of moving wire along the wear movement direction. The interwire wear condition changes from sliding wear to mixed wear (both sliding wear and fretting wear) during the wear process. The wear depth during a single wear cycle has a generally uniform distribution in the wear region, except for the areas near the wear edges where oscillating distributions occur. The distribution of contact pressure is more uniform at the wear center than those at the wear edges, where obvious surface stress concentrations happen. In the initial phase of the wear process, wear scars of the wires extend rapidly and the nonuniformity of contact performance at different wear positions is distinct. As the wear process continues, the increasing rate of the wear depth decreases, and the interwire contact parameters become uniformly distributed.

Casing Wear Prediction Model Based on Casing Ellipticity in Oil & Gas Well-Drilling With Complex Structures

Any casing with perfect integrity within a complex oil and gas development scenario is subject to formation extrusion resulting in ellipticity. This paper proposes a novel casing wear prediction model, which encompasses ellipticity, geometric structural relationships, and the energy dissipation law at work in the casing. Composite structural wear models are also utilized to determine the influence of different drill pipe combinations on casing wear predictions. The casing wear position is predicted based on casing ellipticity. The proposed model yields more accurate casing wear predictions than previous models which do not properly account for casing ellipticity; to this effect, it may more effectively minimize the cost of drilling engineering and safeguard against accidents. The proposed method also outperformed other methods in a case study on a shale gas development project in Fuling, China. The inversion method is applicable to wells with similar structure to the drilled well, where casing wear position can be evaluated very accurately according to caliper logging system measurements. The proposed method facilitates sound decision-making while guaranteeing secure and reliable oil and gas well-drilling with complex structures.

Die Temperature and Wear Analysis of Hot Rotary Forging for Auto Semi-axle

In this paper, a finite element analysis model including Archard wear model of the rotary forging process for auto semi-axle is presented. Based on the software of Deform-3D, this analysis investigates the temperature and wear changing rule during forging. Different initial die hardness and friction factor were selected respectively to simulate rotary forging processes, which initial die hardness from 40 HRC to 65 HRC that the equal increase is 5, and friction factor from 0.15 to 0.5 that the equal increase is 0.5.The results show that the maximum temperature are appeared on the transition fillet of the die and punch, and the peak temperature was 599℃. The die wears decreased rapidly with the hardness raised and the friction factor declined. The highest temperature and seriously wear position are in the transitional zone of the flange.

Wearing-independent hand gesture recognition method based on EMG armband

Electromyographic (EMG) armband with electrodes mounted around the user's forearm is one of the most ergonomic wearable EMG devices and is used to recognize fine hand gesture with great popularity. Definitely, the distributions of signal differ greatly in different wearing positions of armband based on the physiological characters of EMG, which will cause the performance decline and even the inapplicability of the recognition model built in one position. Hence, this paper proposes a wearing-independent hand gesture recognition method based on EMG armband. To eliminate the influence of wearing position, Standard Space is proposed in this paper. Based on the sequential features of EMG in different scales, the wearing position of armband is predicted and helps unify the original features to the proposed space. Then, with the unified signals, fine hand gesture can be recognized accurately and robustly with lightweight Random Forest (RF). The experimental results showed that the recognition accuracy of the proposed method was 91.47% approximately. And compared with the method without fine feature extraction and feature space unification, the performance was improved by 10.12%.

Surface Analysis of Uncoated and PVD Coated Punch at the Hole-Flanging Process

This paper researches the surface condition and wear on the hole-flanging punch when producing a flanged Ø7 mm hole in a steel strip S355J2 + N (1.0577) with a thickness of 3 mm. The hole was flanged by a punch with a defined geometry known as a tangent ogive and described via a caliber radius head (CRH) ratio. During the process, wear of the punch made of hardened tool steel 1.3343 appeared after 20,000 strokes. Thus, a multipurpose coating TiCN-MP deposited via Lateral Rotating Arc-Cathode technology was applied on the punch to extend the punch lifetime. The coated punch was polished to remove droplets after deposition process. By applying TiCN-MP coating, 120,000 strokes were applied to reach the same wear as for the uncoated tool steel. The surface of the punch made of the hardened tool steel for uncoated and PVD coated conditions was researched by scanning electron microscopy after wear, and an energy dispersive X-ray (EDX) analysis was done to identify components of bonded material. In addition, the normal pressure on the punch active surface was studied via a numerical simulation of the hole-flanging process. The position of the high normal pressure is well correlated to the position of the adhesive wear for the uncoated and coated punches.

Using Bluetooth proximity sensing to determine where office workers spend time at work.

BackgroundMost wearable devices that measure movement in workplaces cannot determine the context in which people spend time. This study examined the accuracy of Bluetooth sensing (10-second intervals) via the ActiGraph GT9X Link monitor to determine location in an office setting, using two simple, bespoke algorithms.MethodsFor one work day (mean±SD 6.2±1.1 hours), 30 office workers (30% men, aged 38±11 years) simultaneously wore chest-mounted cameras (video recording) and Bluetooth-enabled monitors (initialised as receivers) on the wrist and thigh. Additional monitors (initialised as beacons) were placed in the entry, kitchen, photocopy room, corridors, and the wearer’s office. Firstly, participant presence/absence at each location was predicted from the presence/absence of signals at that location (ignoring all other signals). Secondly, using the information gathered at multiple locations simultaneously, a simple heuristic model was used to predict at which location the participant was present. The Bluetooth-determined location for each algorithm was tested against the camera in terms of F-scores.ResultsWhen considering locations individually, the accuracy obtained was excellent in the office (F-score = 0.98 and 0.97 for thigh and wrist positions) but poor in other locations (F-score = 0.04 to 0.36), stemming primarily from a high false positive rate. The multi-location algorithm exhibited high accuracy for the office location (F-score = 0.97 for both wear positions). It also improved the F-scores obtained in the remaining locations, but not always to levels indicating good accuracy (e.g., F-score for photocopy room ≈0.1 in both wear positions).ConclusionsThe Bluetooth signalling function shows promise for determining where workers spend most of their time (i.e., their office). Placing beacons in multiple locations and using a rule-based decision model improved classification accuracy; however, for workplace locations visited infrequently or with considerable movement, accuracy was below desirable levels. Further development of algorithms is warranted.

Wear and Reliability Life of Large Modulus Gear Rack

In this paper, based on the Archard wear theory, numerical simulation method and Hertz contact theory, the numerical simulation model of gear rack wear is established under the influence factor of load and hardness for the wear condition of large modulus gear rack. The simulation calculation of its wear process and wear life is realized through the Matlab software. Results show: Along the tooth profile, wear rate of tooth root is greater than the crown. Maximum wear position is decided by comprehensive influence of contact stress and slip distance. The analysis calculation of large module gear rack’s wear process and life can be solved through the method of combining experiment and numerical simulation for good engineering application.

Improvement of lubrication characteristics in the reciprocating fuel pump of marine diesel engines

In this study, we apply circumferential grooves and taper shape to the plunger in order to improve the lubrication characteristics of reciprocating fuel pumps for marine diesel engines. We use the two-dimensional Reynolds equation to evaluate lubrication characteristics with variation of viscosity, clearance, groove and taper for an incompressible, unsteady state flow. Moreover, we use the equilibrium equation of moment and forces in the vertical and horizontal directions to determine the motion of the plunger. The validity of numerical model is verified through the fact that the position of wear is similar to that of minimum film thickness. We investigate the lubrication characteristics of the pump by comparing the dimensionless minimum film thickness, or film parameter. Through numerical analysis, we find that to improve the lubrication characteristics of the pump, applying both circumferential groove and taper shape to the plunger is more effective than applying just either one of them.

Influence of wheel and rail profile shape on the initiation of rolling contact fatigue cracks at high axle loads

ABSTRACTThe influence of wheel and rail profile shape features on the initiation of rolling contact fatigue (RCF) cracks is evaluated based on the results of multi-body vehicle dynamics simulations. The damage index and surface fatigue index are used as two damage parameters to assess the influence of the different features. The damage parameters showed good agreement to one another and to in-field observations. The wheel and rail profile shape features showed a correlation to the predicted RCF damage. The RCF damage proved to be most sensitive to the position of hollow wear and thus bogie tracking. RCF initiation and crack growth can be reduced by eliminating unwanted shape features through maintenance and design and by improving bogie tracking.

Users' psychological perception and perceived readability of wearable devices for elderly people

ABSTRACTAs the population of elderly people in society rises, the importance of technology to assist health management is growing with the demographic shift. Wearable personal computing has been the common solution proposed by related projects to fulfil the needs of elderly people. These add-on devices are attached to the users, and result in uneasiness or discomfort while wearing them in public areas. In this study, three common wearing positions – wrist, upper arm, and neck – were investigated in terms of psychological perception and perceived readability. Twenty-four Taiwanese participants in Miaoli area were asked to wear the designed prototypes for a certain time. The participants completed questionnaires and participated in an open-ended interview. Data of psychological perceptions, visibility, and readability about wearable devices were collected. The results evidenced that the personal attributes of gender, smart device user, and requirement for medical care affect the psychological perception and user attitudes. The statistical results indicated significant differences in elderly people's attitudes towards wearable devices attached to different parts of the body. The wrist was the most favourable location to attach a wearable device.

Online Tool Wear Measurement for Hobbing of Highly Loaded Gears in Geared Turbo Fans

Continuous increase in flight passengers alongside with a high demand for fuel efficiency has led to the development of Geared Turbo Fans (GTF). Being a safety-critical part, the gearbox faces strong safety requirements that also account for sophisticated manufacturing processes and monitoring systems. One major issue is tool wear and the threat of tool breakage during the hobbing process. Due to the high costs of both the raw material and the tool, wear induced tool breakage is a major cost driver. Common practice today is to use each tool for a designated time, but in-situ online wear assessment would result in a major reduction of costs. Tool wear of hobs is not spread equally across all cutting edges; hence the assignment of tool wear to each blade would enable a monitoring system to analyze the individual tool life and predict its operational capability. This research paper discusses the general feasibility of a blade-oriented monitoring system for gear hobbing processes. A correlation between tool wear and effective power is found and analyzed. It can be shown that the respective position of the tool wear changes the effective power signal significantly. These findings enable further research on an online, model based and position-oriented tool wear monitoring system.

Speech Intelligibility in Noise With a Single-Unit Cochlear Implant Audio Processor.

The Rondo is a single-unit cochlear implant (CI) audio processor comprising the identical components as its behind-the-ear predecessor, the Opus 2. An interchange of the Opus 2 with the Rondo leads to a shift of the microphone position toward the back of the head. This study aimed to investigate the influence of the Rondo wearing position on speech intelligibility in noise. Speech intelligibility in noise was measured in 4 spatial configurations with 12 experienced CI users using the German adaptive Oldenburg sentence test. A physical model and a numerical model were used to enable a comparison of the observations. No statistically significant differences of the speech intelligibility were found in the situations in which the signal came from the front and the noise came from the frontal, ipsilateral, or contralateral side. The signal-to-noise ratio (SNR) was significantly better with the Opus 2 in the case with the noise presented from the back (4.4 dB, p < 0.001). The differences in the SNR were significantly worse with the Rondo processors placed further behind the ear than closer to the ear. The study indicates that CI users with the receiver/stimulator implanted in positions further behind the ear are expected to have higher difficulties in noisy situations when wearing the single-unit audio processor.

Pulled Tight and Gleaming: The Stocking’s Position within Eighteenth-Century Masculinity

This article examines the cultural significance of the stocking as an essential accessory of an eighteenth-century man’s attire. Rooted in a material understanding of the stocking through extant garments and archival accounts, this discussion broadens to consider the stocking as a form of cultural currency that spanned visual and popular culture in the eighteenth century. An analysis of the stocking’s visual representation in painted portraiture and graphic satire reveals how it acted as a barometer for British masculinity and subsequently as a visual indicator for the health of the nation, which directly correlated with the stocking’s position and pattern of wear on the leg.

Validation of a computer-assisted method for measurement of radiographic wear in total hip arthroplasty using all polyethylene cemented acetabular components.

Although cemented all polyethylene (PE) cups have been routinely used in total hip arthroplasty for decades, no computer-assisted method for measurement of radiographic wear has ever been specifically validated for these implants. Using a validated hip phantom model, AP plain hip radiographs were obtained consecutively for eight simulated wear positions. A version of Martell's Hip Analysis Suite software dedicated to all polyethylene sockets was used by three different examiners of varied experience. Bias (mean, standard deviation and 95% confidence interval limit), repeatability (standard deviation and 95% limit) and reproducibility (standard deviation and 95% limit) for two-dimensional wear measurements were assessed, as recommended by the current ASTM guidelines. Using this protocol, the dedicated software showed an overall mean bias of 0.089 ± 0.060 mm (mean ± SD), and 0.118 mm for 95% CI limit. Repeatability (intra examiner) standard deviation and 95% limit were respectively 0.106 mm and 0.292 mm. Reproducibility (inter examiner) standard deviation and 95% limit were respectively 0.112 mm and 0.308 mm. Martell Hip Analysis for all PE cemented cups is a reliable and low-cost instrument in the assessment of wear, despite being less precise than its original version dedicated to cementless components.

Design, Realization, and Evaluation of uDirect-An Approach for Pervasive Observation of User Facing Direction on Mobile Phones

A novel method for a mobile phone centric observation of a user’s facing direction is presented. To estimate this direction, our proposed technique exploits the acceleration pattern that can be measured by a smartphone as the user is walking. For an accurate analysis of the acceleration pattern, the proposed approach benefits from a new trigonometric interpolation scheme. Our algorithm is independent of the initial orientation of the device and is adaptable to various wearing positions on a user’s body, which gives the user a larger degree of freedom. A detailed description of the algorithm, which has been customized for a trouser pocket is presented. In addition, complementary hints for adaptation of the algorithm to other wearing positions along with an example of chest pocket position are provided. We have evaluated a prototype implementation of our algorithm on a smartphone, through several field experiments. It has been observed that our algorithm outperforms the conventional GPS and PCA-based techniques in terms of accuracy, reliability and energy consumption. The results also show that our approach has been able to handle the sudden variations of the user’s direction. We have further incorporated our algorithm into a dead-reckoning application as an example of its real-world utility.

Centrifugal pump wear for solid–liquid two-phase flows based on computational fluid dynamics–discrete element method coupling

In the conveying process of a solid–liquid two-phase medium, the wear of the flow passage components is unavoidable. In this study, the solid–liquid two-phase flow in a centrifugal pump was numerically simulated by computational fluid dynamics–discrete element method coupling. For particle diameters up to 3 mm, the particle–particle and particle–wall interactions were considered in the simulation. Two-phase performance and wear experiments for different flow rates and particle concentrations were conducted. The wear experiment was carried out for 48 h at each mass concentration. In these experiments, a paint film method was used to display the wear position, and the wall thickness of the flow passage was measured using an ultrasonic thickness gauge. The results show that the instantaneous wear rate of the impeller, volute, and wear plate in the pump changed periodically with the impeller rotation. The volute wall wear was related to the particle movement. With the increase in the particle mass concentration, the wear rate increased. However, the rate of increase of the wear rate decreased because the particles moved to the wall in the volute to form a particle layer. Increasing the concentration did not linearly increase the effect of the particles on the wall.

The Calculation and Analysis for the Independent Wheels of Tramcar

The wheel/rail profiles in different wear stages are measured using the apparatus of wheel-rail profile. The 3D elastic-plastic FEM contact models are established for the straight line and curves, in which attack angle is considered. Contact problems between the wheels in different wear stages and the worn rail are studied. Contact area, normal contact force, and equivalent Von Mises stress of different cases are analyzed. The obtained results show that the maximum equivalent Von Mises stress reduces and tends to be steady with the independent wheel wearing. Widening the track gauge can have an influence on the variation of wheel wear positions and the wear rules between wheel and rail. When the wheel with a certain attack angle contacts with rail, the maximum equivalent Von Mises stress appears at the contact region between the flange and rail side. The influence of attack angle on the wear between the wheel and rail is quite serious. It is very important to do the research for the further optimization and design of the wheel/rail profiles.

Tool wear model based on least squares support vector machines and Kalman filter

In this study, the least squares support vector machines (LS-SVM) and Kalman filter (KF) technique are used to establish the tool wear estimation model. Tool wear prediction model, based on LS-SVM, is given to describe the mapping relationship between input–output factors. The cutting conditions (feed rate, cutting speed, and depth of cut), cutting time, and wear position constitute the input factors and tool wear is the output parameter of the model. In order to improve the accuracy of the LS-SVM results, the KF technique is used to update the tool wear estimated results of LS-SVM-based model, which is called the LS-KF model, according to the measured tool wear values. Experiment work is performed on machining center for cemented carbide ball-end cutter cutting stainless steel. Those two models (LS-SVM model and LS-KF model) are applied to the actual milling machining to verify their performance. Results show that predicted tool wear based on the proposed LS-KF model has more precision than that of LS-SVM model.