Actual Wear Research Articles

Study on Influence of Diversified Parameters of Vehicle and Track on Wheel Hollow Wear

Wheel hollow wear of high‐speed train is one of the main damage types for the wheel. By optimizing the vehicle and track parameters and matching the wheel‐rail profile, the hollow wear of wheel can be reduced. In order to study the sensitivity of vehicle and track parameters to the wheel hollow wear, the sensitivity of suspension parameters and the track parameters of the CRH2Ctype high‐speed train wheel on the hollow wear of the wheel was studied by the parameter sensitivity analysis method. The concept of the cumulative wear power dissipation was put forward. The distribution characteristics of the wheel hollow wear under the different wheel/rail treads matching were forecasted. The results show that the damping of antihunting motion damper of the vehicle is the most sensitive to the maximum cumulative wear power dissipation of the wheel, followed by the longitudinal stiffness of tumbler journal box node, lateral stiffness of air‐spring suspension, vertical damping of primary suspension, vertical stiffness of track, and vertical damping of track. According to the analysis from the combination of sensitive parameters, the cumulative wear power dissipation is unevenly distributed in the lateral direction of the wheel tread and has the obvious peak area, which is basically the same as the actual wear distribution location in the field. The matching of the LMA wheel tread and the CN60N rail tread is a good choice to slow down the hollow wear and reduce the wheel wear rate. And the wheel reprofiling should be timely carried out, otherwise the wear rate would increase and the hollow wear would become more serious.

Erosive wear resistance evaluation with the hardness after strain-hardening and its application for a high-entropy alloy

Hardness has been regarded as a primary parameter for the wear resistance evaluation of metals for a long time. However, because of work-hardening induced by wear, sometimes there is a big difference between the actual wear resistance and the evaluation with the original hardness (H1). So an experimental hardness test after strain-hardening was suggested, and the effect of this experimental hardness on the evaluation of erosive wear resistance was investigated. Based on the slurry erosion tests of 8 kinds of metals under 90° impingement, a significant positive linear correlation between the erosive wear resistance and the ratio of strain-hardened hardness (H2) and compressive elastic modulus (E) was obtained. And the correlation coefficient (R2) between the value of erosive wear resistance and H2/E ratio increases from 0.61 to 0.89 when the original hardness is substituted by the strain-hardened hardness. Furthermore, the erosive wear resistance of AlCrFeCoNiCu HEA was evaluated by the empirical expression and the difference between the experimental and predicted values is less than 10%. Therefore, the proposed evaluation method with the strain-hardened hardness is practical and effective for the erosive wear resistance evaluation of a candidate metallic material.

Analysis of the evolvement of contact wire wear irregularity in railway catenary based on historical data

ABSTRACTThis paper studies the evolvement of the wear irregularity of contact wire using wire thickness data measured yearly from a section of railway catenary. The power spectral density and time–frequency representation based on the wavelet transform are employed for data analysis, with an emphasis on local wear irregularities that are crucial for contact wire condition assessment. To investigate the cause of wear irregularity evolvement and the mutual influence with the pantograph–catenary dynamic interaction, simulations considering the influence of wear irregularity are carried out based on the finite element method. Analyses of the actual wear irregularities and the dynamic contact force under singular and complex wear irregularities are performed. Although the wear irregularity has limited impact on the pantograph–catenary interaction, it can induce the vibration of pantograph and contact wire that will lead to a notable increase of contact force standard deviation. The evolvement of wear irregularity is closely associated with the span length and dropper distribution of catenary structure and the running direction of pantograph. In addition, it is found feasible to detect the wear irregularity based on contact force, on condition that the sampling frequency is high enough to reflect the indicative frequencies.

Wear Depth Prediction for Steam Generator Tubes Using an Estimated In Situ Wear Coefficient

This study proposes a methodology to estimate time-varying in situ wear coefficient between steam generator tubes in nuclear power plants and their supporting structures. Actual wear depth measurement data of steam generator tubes of OPR1000 (Optimized Power Reactor 1000 MW) plants in Korea were collected and analyzed to investigate the behavior of fretting wear. To determine the in situ wear coefficient, a mathematical expression was developed as a function of various parameters such as measured wear depth time history, work rate, contact geometry of the tube, and its support. These calculated in situ wear coefficients were then used to obtain wear depth history curves. Results obtained were then compared with actual field measurement data to show the validity of the proposed method. Many researchers have obtained wear coefficients under laboratory conditions. However, those coefficients cannot be considered as realistic factors for operating steam generators. The in situ wear coefficient proposed in this study is based on wear measurement data obtained from real operating steam generator tubes. Therefore, they can be used to precisely predict the wear depth of steam generator tubes, thus allowing safe and economical management of steam generators.

How accurate are TheraMon® microsensors at measuring intraoral wear-time? Recorded vs. actual wear times in five volunteers.

The TheraMon® microsensor is the most recent device developed to measure the wear-time of removable appliances. The accuracy has not been validated intraorally. To determine 1) if the TheraMon® microsensor accurately records time when fixed intraorally, and 2) the effect of the intraoral location on the recorded time. A prospective pilot study, using a convenience sample, was carried out in a UK hospital orthodontic department. Five non-patient volunteers wore microsensors positioned palatal to an upper molar, and buccal to a lower molar for 7 days. Differences between actual amount of wear and the wear recorded by each device were calculated. Differences between sites were also examined. The mean daily wear-time recorded by the upper and lower microsensors combined was 23 hours (95% CI 22.6-23.4), which is a mean under-recording of 4% (CI 2.5-5.8%). The maximum daily under-reporting of wear times was 5.5 hours. Microsensors in the lower buccal sulcus recorded wear-times that were closer to actual wear-times. Assumptions made by the TheraMon® microsensors software lead to under-reporting of intraoral wear-time, particularly when placed palatally. These discrepancies could be significant in both clinical practice and research. Adjustment of the microsensor software parameters would improve accuracy, irrespective of the intraoral location.

A New Approach for the Wear Failure Risk of Copper Staves in Blast Furnaces

Copper staves are widely used as cooling systems for blast furnaces. Since the inside wall of the furnaces are completely covered with copper staves, the failure of the system plays a significant role for premature blast furnace relining. Especially the bosh area is the critical part of blast furnaces because it faces high heat load. The damage to the bosh area directly affects the service period of BF’s. The lifetime of furnaces can be prolonged considerably by preventing the premature damage of this section. For this purpose, a new approach has been introduced to define the premature risk factor of copper staves based on design and operation parameters. The data of 34 different blast furnaces obtained from the members of World Steel Assoc. are applied to this new approach to calculate the premature risk factors. The results are recorded and analyzed according to service lifetime and actual wear situations of copper staves. Finally, all these analyzes show that the new approach, which is represented in this paper can be a new design check parameter for blast furnaces and a practical solution to define the premature wear risk of copper staves. Therefore, blast furnace designers and users can extend the blast furnace lifetime by using this new approach resulting in high economic benefits.

Study of spindle power data with neural network for predicting real-time tool wear/breakage during inconel drilling

Digital manufacturing systems are determined to be a major key to enhance productivity and quality mainly due to real-time process monitoring and control capability with instant data processing. During machining, such systems are anticipated to excerpt reliable data within a short time-lapse, monitor tool wear progress, anticipate its wear and breakage, alert the machinist in real time to avoid unexpected failure of tool or machine, and help obtaining quality products. This is vital, especially, when drilling Ni-/Ti-based superalloys because catastrophic failure and premature breakage of tools occur in random manner due to aggressive welding and chipping of tool including the rake and/or flank faces and tool corner.Nowadays, spindle power data are easy to collect directly from modern machine tools and can be made available in production floor for such real-time data processing. This work aims to evaluate spindle power data for real-time tool wear/breakage prediction during drilling of a Ni-based superalloy, Inconel 625. Experiments were performed by varying speed and feed. Spindle power data were collected from the power meter (also called load meter) to feed into the neural network (NN) for functional processing. To understand the reliability of the spindle power data, force data were also collected and compared. The results show that the trends of these two different types of data over cutting time are similar for any feed and speed combinations. The error in NN prediction from actual wear was found to be between 0.8–18.4% with power data as compared to that between 0.4–17.9% with force data. Findings suggest that spindle power data integrated with the artificial intelligence (NN) system can be used for real-time tool wear/breakage monitoring and process control, thus appreciate digital manufacturing systems.

Model-Based Online Tool Monitoring for Hobbing Processes

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 reduction of costs as tools can be used to their individual potential. Tool wear of hobs is not spread equally across all cutting edges; hence the assignment of tool wear to each tooth would enable a monitoring system to analyze the individual tool life and predict its operational capability. This research paper presents a method of using effective power signals in combination with a predictive model to determine the actual wear status of each tooth. The model uses the chip geometry and a force model in order to predict the expected torques of the spindle and compares them in real-time with measurement data. An algorithm then estimates the wear status of each tooth. These findings enable further research on an online, model based and position-oriented tool wear monitoring system.

여자 대학생의 니트웨어 착용실태와 선호 디자인 연구

Knitwear has been used as an active and functional clothing item due to its flexible and soft nature. Diverse design expressions have made knitwear into an essential fashion item for people today, who are constantly seeking for ways to display their individualism. The purpose of this study is to analyze the actual wearing conditions, and the preferred designs of knitwear for female college students in order to provide a baseline data, which can be used to develop knitwear designs for the subjects of the study. Survey by questionnaire of 135 female college students in 3 universities in Seoul were analysed. The results of the study are as follows: First, the most owned knitwear were sweaters and cardigans. Knitwear was viewed as soft and warm, as well as versatile. It was not restricted to certain sizes, and was comfortable to wear for different activities. Seound, the most preferred items were sweaters and cardigans. The most preferred styles were round neckline sweaters and open V-neckline cardigans. Third, the most preferred designs were plain designs with achromatic colors and wool-blended fabrics. The most preferred images were simple images. The most preferred fit was loose enough for little bit of room inside. Fourth, appropriateness and design of the knitwear were assessed during the purchasing stage. the most preferred method of purchase was purchasing via online stores after researching the knitwear through various channels, such as store visits and the Internet. The preferred price of knitwear was below 100,000 KRW. Fifth, the most common complaints were as follows: changes in the shape and quality of the knitwear after a wash, appearance of nap, and loose threads. In short, it is necessary for female college students to develop high quality knitwear with designs that can display individuality, while being simple.

Study on Erosion Wear Resistance of Internal Coating of Wear-Resistant FRP Compound Pipe

A resin matrix compound coating is prepared by taking epoxy as the matrix and α-Al2O3 particle as the reinforced phase. By simulating the actual wear conditions of pipes in the heavy medium coal preparation in a laboratory, the paper explored the change law of the erosion wear resistance of wear-resistant coating with different reinforced particle sizes and abrasion angles, and discussed the wear mechanism by combining with abrasive appearances. The results show that reinforced particles with a lager particle size (60 mesh) are of excellent erosion wear resistance when the erosion wear particle is smaller (200 mesh), and the α-Al2O3 particle wear-resistant epoxy coating with a particle size of 60-80 mesh is of good erosion wear resistance under the condition of heavy medium coal preparation and is suitable to be a wear-resistant coating material.

Failure Analysis of Wear Block of Crush Deck Used in Sinter Plant

Failure analysis of wear block used in the crush deck of a Sinter Plant was carried out. Crush deck acts as a platform to transfer the hot sinter cake from sinter machine to crushing unit. Hot sinter cake with a temperature around 800 °C falls on the crush deck from the discharging end of rotating sinter machine. This investigation consists of visual observation, chemical analysis, characterization of microstructures, energy dispersive spectroscopy, and measurement of hardness. Analysis revealed that this is an iron-based material with Cr–Ni alloying with higher hardness and lower toughness, which was due to improper microstructure. Microstructure revealed a large number of primary carbides along with needle-shaped carbides, which drastically reduce the toughness of the material. Application point of view the wear block should have optimum combination of toughness and wear resistance at elevated temperature; however, analyses showed the actual wear block had with higher wear resistance and lower toughness. This was reflected in the undesirable microstructure observed during metallographic study. It was thus concluded that the component failed before a proper life cycle was achieved due to poor material properties. Based on the failure analysis suitable heat treatment process was recommended. Metallurgical study carried out on the suggested material, showed significant improvements in material property. Trial of recommended wear block was taken at the plant level and life of the recommended material improved twice than that of previous one.

보건관리전문기관의 작업환경관리 지도에 따른 일부 지역 사업장 보건업무담당자와 근로자의 실천도

Objectives: This study aimed to provide basic data for the improvement of the guidance services for the management of the workplace environment of the specialized health management institution, by making inquiries on the perception and extent of practice by health managers and workers in the workplace. Methods: Workplaces with officially noted environmental hazards of noise, organic compounds and/or dust-metals were selected in a South Korean metropolitan city in 2015. The workplace health managers(hereinafter referred to as 'manager') and workers at 97 workplace were interviewed. Managers are those who are in charge of health management at the corresponding workplace and the workers were subjected to in-depth interviews by sampling one worker for each of the workplace. Results: The majority of the managers acknowledged the guidance services of the specialized health management institution affirmatively. Regarding the extent of practice in accordance with the guidance on engineering improvement, only 23 managers(37.1%) responded. With respect to education, 40 managers(41.2%) responded that it was implemented along with 35 workers(36.1%) who responded that they received education, showing no significant difference between manager and worker. Regarding the actual wearing of the protective equipment, however, 83 of the manager(85.6%) insisted that workers wore the protective devices while only 44 workers(49.5%) responded that they actually wore the devices, thereby illustrating a significant difference between managers and workers. Conclusions: These results suggest the urgent necessity of improvement in the mechanism of guidance services of the specialized health management institution for the workplace environment management.

Investigation on the novel measurement for fabric wrinkle simulating actual wear

It is very important to measure fabric wrinkling objectively and accurately. However, the most commonly used measurements could not be employed to realistically evaluate and predict how fabric will resist wrinkle when worn on human body. In our previous study, an equipment of measuring fabric wrinkling that can simulate actual wear was proposed. In this paper, we conduct further investigation on the measurement for fabric wrinkle-simulating actual wear, including improving the equipment, validating its repeatability, and clarifying its more accurate relationship with the wrinkle recovery angle (WRA) method. Results show that the measuring repeatability of the method is much better than WRA method and fabric wrinkling in the warp and bias direction plays more important part than weft. Therefore, it is advisable that WRA of the bias should be increased, whose measurement stability is the best in the WRA method as well. Equations of Wrinkle Density (WD) with WRAs are established, which can be used to estimate wrinkling of clothes after actual wear only by several WRAs of fabrics, avoiding the tedious clothes making and trial work.

A Study on Actual Wearing Conditions and Optical Properties of Sports Sunglasses in Korea

A Study on Actual Wearing Conditions and Optical Properties of Sports Sunglasses in Korea

Characterization of wear and prediction of wear zone locations on the rake face using Mamdani fuzzy inference system

In order to improve the performance of the cutting tool, third-generation tools with multi-layered nanocoatings on the rake face are used. During machining, the chip–tool interactions depict that although the tool wear on the rake face is located in the close proximity of the cutting edge, that is, within 800 µm, all the commercially available cutting tools have the coatings on the entire rake face. Taking into account the tribological properties required by the rake face close to the cutting edge, that is, high wear resistance and low friction, this study makes an attempt to identify, characterize and locate the actual wear zones/regions in terms of hard and soft zones in the chip contact area of tungsten carbide (WC) inserts close to the cutting edge in turning. Mamdani fuzzy inference system model was developed, trained with the sample experimental data and tested with the test data. The simulated results showed that the average error values of edge chipping (in X- and Y-directions), nose damage and crater wear (in X- and Y-directions) are about 2.37%, 3.01%, 2.86%, 2.66% and 1.89%, respectively. The fuzzy model developed in this study showed remarkable prediction of the wear zone locations and is also helpful for the researchers to decide the type of coating (hard and soft) along the specified zones for reducing the cost of production.

Coupling behavior between adhesive and abrasive wear mechanism of aero-hydraulic spool valves

Leakage due to wear is one of the main failure modes of aero-hydraulic spool valves. This paper established a practical coupling wear model for aero-hydraulic spool valves based on dynamic system modelling theory. Firstly, the experiment for wear mechanism verification proved that adhesive wear and abrasive wear did coexist during the working process of spool valves. Secondly coupling behavior of each wear mechanism was characterized by analyzing actual time-variation of model parameters during wear evolution process. Meanwhile, Archard model and three-body abrasive wear model were utilized for adhesive wear and abrasive wear, respectively. Furthermore, their coupling wear model was established by calculating the actual wear volume. Finally, from the result of formal test, all the required parameters for our model were obtained. The relative error between model prediction and data of pre-test was also presented to verify the accuracy of model, which demonstrated that our model was useful for providing accurate prediction of spool valve’s wear life.

대학생의 신체부위별 추위지각 반응과 착의 행동

This study investigates gender differences in cold perceptions and wearing behaviors for cold adaptation. A questionnaire composed of items on cold perceptions, intentions toward wearing additional clothing, and clothing for outdoor environments, among others, was used. Each item in the survey targeted 260 male (MS) and female (FS) college students evaluated using a five-point Likert-type scale. Data were statistically analyzed using the independent sample t-test and correlations. Main results can be summarized as follows: MS subjects showed lower dependence on the thermal insulation of clothing because they felt less cold and had the better ability to cope with cold. MS subjects had higher dependence on underwear during cold seasons, and FS subjects tended to wear heavier clothing to compensate for their cold feet with insufficient insulation. In addition, it was preferable to estimate thermal effects of actual wear by taking into account gender differences in the physique. The study is limited in that the room temperature and the actual amount of clothing were not measured, which offers an avenue for future research.

Copper wire bonding ready for industrial mass production

Copper wire as a bonding material for the top side connection of power semiconductors is highly desired. One current drawback in heavy copper wire bonding is the relatively low lifetime of the consumables. The bonding tool wear mechanisms and the corresponding factors are investigated. To reduce wear, different approaches are tested in long-term bonding tests. Optimized bonding tool tip geometry and tool material are two of these factors. Optimized bonding parameters were investigated as well and show a significant improvement in bonding tool lifetime. Wear and lifetime of the cutter and the wire guide are also examined. Additionally, the impact of bonding tool wear on different aspects of bond quality is addressed. It is also shown how wear can be monitored by machine process data recording and how a derived signal correlates to the actual wear status. These major advances in heavy copper wire bonding now make it a robust, reliable and efficient interconnection technology.

Qualitative Research on Actual Wearing Conditions and Satisfaction of Rifle Shooting Clothing

This study investigates actual wearing conditions and satisfaction based on qualitative research for rifle shooting clothing. The survey was conducted in two ways: in-depth interviews of 4 rifle shooting experts and subjective questionnaires for 18 active rifle shooters. They agreed on the importance of rifle shooting wear to minimize body sway and contribute to a balanced body posture. Most rifle shooters purchase made-to-measure rifle shooting clothing at a domestic store, but the clothing often needs extra adjustments due to an uncomfortable fit. Current fabric for rifle shooting clothing consists of a cotton canvas with a polyester mix; however, rifle shooters are unsatisfied with its stiffness in hot and wet conditions. Due to the specific fabric features, rifle shooting clothing should not be washed despite year-round use that represents another point of dissatisfaction. Rifle shooters always wear specially designed underclothes to improve shooting skills and comfort sensation. In conclusion, it is necessary to develop well fitted and comfort rifle shooting clothing that could improve shooters skills based upon this study.

A randomized clinical trial comparing reported and measured wear rates in clubfoot bracing using a novel pressure sensor.

The treatment of clubfoot by the Ponseti method requires the utilization of a foot abduction orthosis (FAO) after manipulation and casting. Adherence to this protocol, specifically FAO wear rates, has been postulated to improve treatment outcomes. Our hypothesis was that caregiver-reported wear rates were significantly less than actual wear rates in these braces. A randomized prospective study of 67 children, aged 0 to 3 years old with idiopathic clubfoot, treated using the Ponseti technique for idiopathic clubfoot, was undertaken after IRB approval. Participants were randomized into 3 groups: a functioning pressure-based sensor (group FPS) attached to the FAO (21 patients), a nonfunctioning sensor (NFPS group) attached to the FAO (24 patients), or no sensor (NS group) (22 patients). All caregivers filled out a diary of subjective wear rates. Reported and actual wear rates were recorded as a percentage of the entire day and compared. In the FPS group, the average actual wear rate for months 1, 2, and 3 were 91.7% (15 patients; 72.7% to 97.0%), 86.8% (9 patients; 60.5% to 96.3%), and 77.1% (7 patients; 52.6% to 95.8%), respectively. The average self-reported wear rate in the FPS group in months 1, 2, and 3 were 94.9% (13 patients; 93.1% to 98.7%), 95.6% (10 patients; 92.3% to 99.4%), and 94.8% (11 patients; 82.8% to 99.6%), respectively. The most predictive factor in determining a patient's decrease in the overall wear rate was a drop in the wear rate between months 1 and 2 (P<0.001). The reported wear rates were not statistically different between any of the 3 groups (P<0.01). By using a novel method of pressure measurement, which documented FAO wear, we have shown a significant decline in wear rates from months 1 to 3. These actual FAO wear rates did not match their reported rates, thus putting into question previous assumptions about reported brace compliance. The largest drop in wear rates occurred from months 2 to 3. This study provides the first objective measurement of FAO brace wear in patients undergoing the Ponseti method of treatment. Level II.