Artykuły w czasopismach na temat „Seals (Cylinders)”
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1
Mrzljak, Vedran, Jan Kudláček, Đerzija Begić-Hajdarević i Jelena Musulin. "The Leakage of Steam Mass Flow Rate through the Gland Seals – Influence on Turbine Produced Power". Journal of Maritime & Transportation Science 58, nr 1 (czerwiec 2020): 39–56. http://dx.doi.org/10.18048/2020.58.03.
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In this paper is presented an analysis of gland seals operation and their influence on the performance of low power steam turbine with two cylinders and steam reheating, which can be used in marine applications. Performed analysis presents a comparison of steam turbine main operating parameters when gland seals operation is neglected (as usual in the most of the literature) and when steam mass flow rates leaked through all gland seals are taken into consideration. Steam mass flow rate leakage through all gland seals reduces produced power of the whole turbine and both of its cylinders. Operation of gland seal mounted at the inlet in the first cylinder of any steam turbine (cylinder which operates with the steam of the highest pressure) has the most notable influence on the reduction of the whole turbine produced power. Gland seal mounted at the outlet of the last turbine cylinder (cylinder which operates with the steam of the lowest pressure) did not have any influence on the reduction of steam turbine produced power. In any detail analysis of a steam turbine (especially the complex turbine with multiple cylinders), gland seals operation should be considered due to their notable influence on the turbine performance.
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Maxwell-Hyslop, K. R. "A Note on the Anatolian Connections of the Tôd Treasure". Anatolian Studies 45 (grudzień 1995): 243–50. http://dx.doi.org/10.2307/3642923.
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Since the detailed study by Edith Porada of the cylinder seals and small objects from the celebrated treasure found in the temple of Mont at Tôd in Upper Egypt, questions concerning its origin and date still remain unanswered. Porada suggested that in addition to seals from Eastern Iran and possibly Afghanistan, a North Syrian origin for two of the cylinders seems a distinct possibility. Two other cylinder seals were carved in Mesopotamian style, one of them being datable to the period of the Third Dynasty of Ur. She also showed conclusively that there are no cylinders which can be dated later than 1800 B.C. (Middle Chronology) and that the latest cylinders belonged to the Isin-Larsa period. Her conclusions concerning the origin of the treasure and the importance of parallels for the amulets and other small objects with material from Mari and Ebla are entirely convincing. A recent study by Christine Lilyquist stresses the evidence for a date within the reign of Amenemhet II for the deposition of the treasure which was found in four metal boxes inscribed with the king's name. While in studies concerning the 153 silver vessels Cretan and Mycenaean prototypes have been cited, Anatolia has not received so much attention. Here it will be suggested that there is considerable recently published evidence from Anatolia and Syria which is relevant to the Tôd silver cups, and that a consideration of recently published textual material from Mari, Ebla, Rimah and Brak may also be useful.
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Mazza, Luigi, i Edoardo Goti. "Failure and Damage of Reciprocating Lip Seals for Pneumatic Cylinders in Dry Conditions". Lubricants 12, nr 4 (4.04.2024): 119. http://dx.doi.org/10.3390/lubricants12040119.
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Lip seals are components subjected to high mechanical stress and they are responsible for many out-of-service in pneumatic cylinders. The aim of this work is the development of an experimental methodology to evaluate lifetime duration and analyse failures and damages of rod lip seals for pneumatic cylinders. A dedicated test bench was designed and manufactured which reproduces actual working conditions of the seals i.e., compressed air action (seal pressurisation) and relative linear reciprocating motion. Three types of seals made of two elastomers (NBR and polyurethane) were tested; dry condition was considered to speed up the tests. The influence of geometric parameters like seal seat dimension and seal axis misalignment with respect to the rod axis, was analysed by multiple experimental tests. Results in terms of seal life duration and failure modes are presented which allow comparison of seals performance and provide a helpful tool to end-users in a proper selection of seals geometry, material and key working parameters.
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Korzekwa, Joanna, Marek Bara i Sławomir Kaptacz. "Al2O3/WS2 Surface Layers Produced on the Basis of Aluminum Alloys for Applications in Oil-Free Kinematic Systems". Materials 14, nr 24 (15.12.2021): 7738. http://dx.doi.org/10.3390/ma14247738.
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The article presents the results of an aluminum oxide layer doped with monolayer 2H tungsten disulphide (Al2O3/WS2) for applications in oil-free kinematic systems. The results concern the test carried out on the pneumatic actuator operational test stand, which is the actual pneumatic system with electromagnetic control. The cylinders of actuators are made of Ø 40 mm aluminum tube of EN-AW-6063 aluminum alloy which is used in the manufacture of commercial air cylinder actuators. The inner surfaces of the cylinder surfaces were covered with an Al2O3/WS2 oxide layer obtained by anodic oxidation in a three-component electrolyte and in the same electrolyte with the addition of tungsten disulfide 2H-WS2. The layers of Al2O3 and Al2O3/WS2 obtained on the inner surface of the pneumatic actuators were combined with a piston ring made of polytetrafluoroethylene with carbon (T5W) material and piston seals made of polyurethane (PU). The cooperation occurred in the conditions of technically dry friction. After the test was carried out, the scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) analysis of the surface of the cylinder bearing surfaces and piston seals of the pneumatic cylinders was performed. The analysis revealed the formation of a sliding film on the cylinder surface modified with tungsten disulfide, as well as on the surface of wiper seals. Based on the SEM/EDSM tests, it was also found that the modification of the Al2O3 layer with tungsten disulfide contributed to the formation of a sliding film with the presence of WS2 lubricant, which translated into smooth cylinder operation during 180 h of actuator operation. The cylinder with the unmodified layer showed irregular operation after approximately 70 h thereof.
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Shanbhag, Vignesh Vishnudas, Thomas Meyer, Leo Caspers i Rune Schlanbusch. "Acoustic emission based condition monitoring study of piston rod seals by varying speed and pressure parameters". Annual Conference of the PHM Society 12, nr 1 (3.11.2020): 9. http://dx.doi.org/10.36001/phmconf.2020.v12i1.1133.
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Hydraulic cylinders are used in a wide range of applications such as oil drilling equipment, construction vehicles and manufacturing machines. Seal failure is one of the primitive causes of failure in hydraulic cylinders, possibly leading to fluid spill, unscheduled maintenance, reduced availability and thus leading to lower productivity. Regular visual inspection of seals without affecting the productivity is difficult as the seals are placed internally in the hydraulic cylinder requiring disassembly of the piston. Therefore, condition monitoring is required to assess the current health of the seals. There have been successful attempts made in literature for the assessment of seal quality using acoustic emission-based condition monitoring. However, there have been very few studies performed to diagnose the seal failure under varying speed and pressure parameters. Therefore, this study aims at increasing the understanding of seal failure under varying speed and pressure conditions through correlation with the acoustic emission signal. Experiments were performed on a hydraulic test rig using unworn, semi-worn and worn piston rod seals. For each seal wear condition, experiments were performed for five strokes at pressure conditions of 10, 20, 30 and 40 bar and speeds of 50 mm/s and 100 mm/s. Continuous acoustic emission data were acquired during all the tests. The acoustic emission signal of each piston rod stroke was analyzed using different acoustic emission features such as power spectral density, root mean square, peak, mean frequency, median frequency and band power. From the acoustic emission analysis, by using power spectral density, mean frequency and median frequency feature it is possible to identify and segregate unworn seal, leakage due to semi-worn seal and leakage due to worn seal in the test rig. The acoustic emission-based condition monitoring methodology developed in this study lays a strong foundation for further research to develop real-time monitoring of the piston rod seal in hydraulic cylinders that are used in the offshore industry.
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Shanbhag, Vignesh Vishnudas, Thomas Meyer, Leo Caspers i Rune Schlanbusch. "Diagnostics of seal and rod degradation in hydraulic cylinders using acoustic emissions". PHM Society European Conference 5, nr 1 (22.07.2020): 8. http://dx.doi.org/10.36001/phme.2020.v5i1.1173.
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External leakage from hydraulic cylinders is of a major concern for the offshore oil and gas industry. This occurs mainly as a result of physical damage to the piston rod or due to degradation of the piston rod seals. Numerous studies have been conducted to diagnose leakage from hydraulic cylinders due to seal failure using fluid, pressure, accelerometer or acoustic emission-based condition monitoring techniques. However, very few attempts have been made to diagnose multiple faults in hydraulic cylinders at the same time. Therefore, in this study, acoustic emission-based condition monitoring technique is used to detect and separate acoustic emission features due to different faults that are observed in hydraulic cylinders. An experimental study was performed on a test rig using water glycol as hydraulic fluid. Experiments were performed with different combinations of seals (unworn, semi worn and worn seals), and piston rods (unworn and worn). Acoustic emission features such as root mean square, peak, mean, kurtosis, skewness, mean frequency, median frequency and bandpower were used to identify seal and rod conditions. By using acoustic emission median frequency and mean frequency features it was possible to detect and separate leakage, and seal and rod degradation in the test rig over a large range of hydraulic working pressures. This study indicates that acoustic emission monitoring can be a strong basis for future research to identify and segregate other types of faults that are observed in hydraulic cylinders.
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Firnandius, Jefvin, Agus Halim i Agustinus Purna Irawan. "PERANCANGAN SISTEM HIDROLIK PADA PINTU WINGBOX BERKAPASITAS 2 TON". POROS 18, nr 2 (24.10.2023): 96–103. http://dx.doi.org/10.24912/poros.v18i2.18755.
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Currently, many innovations are being made in developing a technology to facilitate human work. One of these technologies is the hydraulic cylinder. Hydraulic cylinders were created to facilitate human work, especially in the industrial sector. Hydraulic cylinder, using a liquid or so-called liquid fluid, to be able to make the hydraulic cylinder work. In the hydraulic cylinder components, there are cylinder axles, pistons and cover seals. In general, hydraulic cylinders can be used for wingboxes. A wingbox is a box on a truck, which can be opened from the side with the help of a hydraulic cylinder. This journal was created to study how the simulation of hydraulic cylinder components when working. The design method used is the reverse engineering method, where the components that have been designed are then simulation is made to find out how strong the component is in holding the load when the component is working. The simulation is carried out using the Autodesk Fusion 360 application to find out how strong the hydraulic cylinder works in bearing the load. The results of this method are obtained when the simulation results of the hydraulic cylinder have been obtained.
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Ali-Hikmat Ahmadov, Ali-Hikmat Ahmadov, i Ruslan Starchevoy Ruslan Starchevoy. "THE RELIABILITY OF A TWO-WAY HYDRAULIC CYLINDER". ETM - Equipment, Technologies, Materials 14, nr 02 (18.04.2023): 05–09. http://dx.doi.org/10.36962/etm14022023-05.
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A hydraulic cylinder is a volumetric hydraulic motor that converts the energy of the fluid flow into various types of movement of the output link. The use of volumetric hydraulic drives with a hydraulic cylinder working element in all possible fields of industry does not require high capacities. One of the advantages is the ease of operation and overload protection. There are also disadvantages. For example, the hydraulic cylinder depends on the working fluid and in case of contamination it may fail, and therefore the reliability of the hydraulic cylinder decreases. In order to protect hydraulic cylinders from moisture and dirt entering them, as well as to increase their reliability, seals with dirt-removing rings are provided. When assembling or disassembling hydraulic cylinders, important conditions must be taken into account, since failure to comply with these conditions can lead to a defect. Considerable efforts have been made to the parts, so some manual operations are excluded when assembling and disassembling hydraulic cylinders. The reliability of the hydraulic cylinder and, consequently, its reliability are the main topic of the study. Hydraulic cylinders can be of translational action and rotary action. Translational ones include: piston, plunger, telescopic. Reciprocating, in turn, can be one-sided and two-sided. If it is required to create an effort in only one direction, a one-way hydraulic cylinder is designed. At the beginning of the work, a diagram of a volumetric hydraulic drive and its principle of operation is presented. Special attention is paid to assessing the reliability of the hydraulic cylinder. In conclusion, the results of the analyses and the conclusions of the calculations are given. The change in the reliability of the hydraulic cylinder over time was also indicated and the reasons for this change were named. Keywords: Reliability, hydraulic cylinder, hydraulic drive, failure, reliability assessment, pipeline, pump, valve, operating time, hydraulic distributor.
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Borisov, V. I., V. V. Kuznetsov, V. N. Vodyakov i A. V. Kotin. "Experimental assessment of wear and plastic deformations of the hydraulic cylinder elastomeric seals". Traktory i sel hozmashiny 79, nr 10 (15.10.2012): 23–25. http://dx.doi.org/10.17816/0321-4443-65986.
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Lothigius, Fredrik, i Jutta Etzkorn. "Intelligent Testing Tools". Industrial Vehicle Technology International 27, nr 1 (marzec 2019): 134. http://dx.doi.org/10.12968/s1471-115x(23)70446-7.
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Sârbu, Flavius Aurelian, Felix Arnăuţ, Andrea Deaconescu i Tudor Deaconescu. "Theoretical and Experimental Research Concerning the Friction Forces Developed in Hydraulic Cylinder Coaxial Sealing Systems Made from Polymers". Polymers 16, nr 1 (4.01.2024): 157. http://dx.doi.org/10.3390/polym16010157.
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Optimizing the energy efficiency of hydraulic cylinder modern sealing systems requires, among other things, minimizing the developed friction forces. This can be achieved by manufacturing seals from polymer-based polytetrafluoroethylene-type materials (Virgin PTFE and filled PTFE) or from thermoplastic polyurethane elastomers. This paper presents a procedure for calculating and experimentally determining the friction forces developed in the coaxial sealing systems of hydraulic cylinders pistons. Three sealing systems made from different materials were tested under varying conditions of pressure and velocity on an experimental test stand set up by the authors. The paper concludes with data and recommendations for the selection of the optimum seal material in order to maximize energy efficiency. Our comparative research conducted on the seal materials led to the conclusion that for reducing friction forces in hydraulic cylinders, Virgin PTFE is the most adequate.
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Chen, Xiaolan, Fuquan Tu, Feng Gao, Heming Cheng i Shixiong Xing. "Variable Gap Sealing Technology of a Hydraulic Cylinder Based on Magnetic Shape Memory Alloy". Coatings 11, nr 8 (9.08.2021): 950. http://dx.doi.org/10.3390/coatings11080950.
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The synergistic control of resistance reduction and sealing poses challenges to enhancing the rapid dynamic response ability of servo hydraulic cylinders; the key to solving this problem is effectively controlling the sealing gap value. In this study, a micro-variation between the hydraulic cylinder and the piston based on the disadvantage of conventional seals, constant gap seals, and lip gap seals was constructed; MSMA assist support blocks were designed on the piston to form a gap seal strip; then, the sealing gap value could be changed by controlling the magnetic field intensity. Simultaneously, the effects of magnetic field strength, parts-manufacturing precision, temperature, and hysteresis on the micro-variation in the MSMA were analyzed, and effective solutions were proposed. Finally, experiments on the magnetic field, temperature, and hysteresis were conducted by the measurement system. The results showed that the variable value of the sealing gap with the MSMA is feasible under ideal conditions, and can effectively change the amount of MSMA expansion by controlling the magnetic field strength, temperature, preload, etc., and then change the amount of the sealing gap of the hydraulic cylinder. This is the key to achieving friction and sealing control, which plays a crucial and active role in improving the efficiency of hydraulic systems. However, the impact of hysteresis effects cannot be ignored, which will be the main problem to be solved in the future.
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Matuszewski, Leszek, i Piotr Bela. "New Designs of Magnetic Fluid Seals for Reciprocating Motion". Polish Maritime Research 28, nr 4 (1.12.2021): 151–59. http://dx.doi.org/10.2478/pomr-2021-0057.
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Abstract The operating conditions of magnetic fluid seals during reciprocating motion are so different from those observed in rotating motion that the use of their conventional structures for reciprocating motion seals yields no good results. The analysis of the sealing mechanism of magnetic fluid seals in reciprocating motion shows that the operation of these seals is affected by the carry-over phenomenon and magnetic fluid film deformation in the sealing gap, which depends on the velocity of the reciprocating motion. The reduced amount of magnetic fluid in the sealing gap caused by the reciprocating motion of the shaft is the main reason for seal failures. The paper presents a short characterisation of magnetic fluid sealing technology, the principle of sealing, the operation of the magnetic fluid and the seal failure mechanism in linear motion of the shaft. Moreover, some new structural designs of hybrid seals, being combinations of typical hydraulic seals with magnetic fluid seals for reciprocating motion, and some examples of magnetic fluid sealing structures for hydraulic cylinders and piston compressors which have practical application values are presented.
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Zaichikov, A. F. "Design of mobile seals of gas chambers of cylinders". Russian Engineering Research 27, nr 7 (lipiec 2007): 452–53. http://dx.doi.org/10.3103/s1068798x07070106.
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Belforte, Guido, Terenziano Raparelli i Luigi Mazza. "Life tests on elastomeric lip seals for pneumatic cylinders". Tribotest 3, nr 3 (marzec 1997): 251–66. http://dx.doi.org/10.1002/tt.3020030303.
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Qian, Pengfei, Chenwei Pu, Lei Liu, Xiang Li, Bing Zhang, Zhenye Gu i Deyuan Meng. "Development of a new high-precision friction test platform and experimental study of friction characteristics for pneumatic cylinders". Measurement Science and Technology 33, nr 6 (25.02.2022): 065001. http://dx.doi.org/10.1088/1361-6501/ac51a6.
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Abstract In order to achieve high-precision pneumatic cylinder friction test, this paper proposes a new direct measurement method based on electric cylinder in which the axially acting forces from the compressed air in the two facing pneumatic cylinders cancel each other out and the detected value of the force transducer is just friction. For the sake of the implementation of the method, a new low-cost test method for identifying deadband of proportional directional valve was proposed, and a set of fuzzy PI constant pressure control system was designed to cope with a certain degree of leakage in the chamber. Based on the above, a friction test platform with two pneumatic cylinders facing each other was eventually built to study the influence of pressure, pressure difference, and piston speed on the friction of two commonly used different types of pneumatic cylinders. Through multiple sets of tests, it is found that when the lip seals are used in pairs between the piston and the inner wall of the cylinder, the friction between the piston and the cylinder is only related to the sum of the two chamber pressures, but not to the pressure difference between the two chambers. When the O-ring seal is used between the piston and the inner wall of the cylinder, the friction between the piston and the cylinder is related not only to the pressure of the two chambers, but also to the pressure difference between the two chambers. In addition, a series of comparative tests with the traditional single-cylinder friction test method directly demonstrate the effectiveness of the proposed new method.
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Jain, Lalit K., i Robert C. Wetherhold. "Viscoelastic Analysis of Concentric Cylinders for Composite Materials and Seals". Journal of the American Ceramic Society 72, nr 10 (październik 1989): 1844–49. http://dx.doi.org/10.1111/j.1151-2916.1989.tb05989.x.
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Burenin, V. V. "New seals for the moving joints of hydraulic power cylinders". Russian Engineering Research 31, nr 10 (październik 2011): 1036–38. http://dx.doi.org/10.3103/s1068798x11100042.
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Borisov, V. I., V. V. Kuznetsov i V. N. Vodyakov. "Tribological properties of hydraulic cylinders' sealings polymer materials". Traktory i sel hozmashiny 79, nr 2 (15.02.2012): 40–43. http://dx.doi.org/10.17816/0321-4443-69389.
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The results of research of tribological properties of polymeric materials for the seals of movable connections are brought in conditions of volume compression using the method of complete multifactorial experiment. Regressive equations adequately describing the dependence of wear intensity and friction coefficient of materials at their co-operating with a counter-body (steel of 40Х), from hydrostatical pressure, speed of skidding and temperature of working liquid are given. It is determined that the preferable complex of tribological descriptions is possessed by the rubber under the code number 7-ИРП-1269″ and the fluorine plastic Ф4К20″.
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Noori, Nadia S., Vignesh V. Shanbhag, Surya T. Kandukuri i Rune Schlanbusch. "Data Driven Seal Wear Classifications using Acoustic Emissions and Artificial Neural Networks". PHM Society European Conference 7, nr 1 (29.06.2022): 368–75. http://dx.doi.org/10.36001/phme.2022.v7i1.3327.
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The work presented in this paper is built on a series of experiments aiming to develop a data-driven and automated method for seal diagnostics using Acoustic Emission (AE) features. Seals in machineries operate in harsh conditions, and seal wear in hydraulic cylinders results in fluid leakage, and instability of the piston rod movement. Therefore, regular inspection of seals is required using automated approaches to improve productivity and to reduce unscheduled maintenance. In this study, we implemented a data-driven diagnostics approach which utilizes AE measurements along with light weight Artificial Neural Networks (ANN) as a classifier to investigate the performance and resources (hardware & software) required for implementing a real-time soft sensor unit for monitoring seal wear condition. We used a feedforward multilayer perceptron ANN (Scaled Conjugate Gradient- SCG algorithm) that is trained with the back propagation algorithm, which is a popular network architecture for a multitude of applications (automotive, oil and gas, electronics). We benchmark the developed method against previous work conducted based on Support Vector Machine (SVM), and we compare ANN performance in classifying the running condition of seals in hydraulic cylinders by applying it to both raw (full frequency spectrum) and down sampled frequency measurements. The experiments were performed at varying pressure conditions on a hydraulic test rig that can simulate fluid leakage conditions like that of hydraulic cylinders. The test cases were generated with seals of three different conditions (unworn, semi-worn, worn). From the AE spectrum, the frequency bands were identified with peak power and by heterodyning the signal. This technique results in 10X down sampling without losing the information of interest. Further, the signal was divided into smaller “snapshots” to facilitate rapid diagnosis. In these tests, the diagnosis was made on short-time windows, as low as 0.3 seconds in length. A general set of 16 time and frequency domain features were designed. Then a training set was developed using relevant set of features (4, 5, and 16 features). The data was used to train the ANN (70% training – 30% test & validation) and SVM (60 % training - 40% test and validation). Classification of down sampled measurements, both ANN and SVM were able to accurately classify the status irrespective of the pressure conditions, with an accuracy of ~99% with execution time less than seconds. Therefore, the proposed approach can be applied as part of an automated seal wear classification technique based on AE and ANN/SVM and can be used for real-time monitoring of seal wear in hydraulic cylinders.
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Shanbhag, Vignesh V., Thomas J. J. Meyer, Leo W. Caspers i Rune Schlanbusch. "Defining acoustic emission-based condition monitoring indicators for monitoring piston rod seal and bearing wear in hydraulic cylinders". International Journal of Advanced Manufacturing Technology 115, nr 9-10 (28.05.2021): 2729–46. http://dx.doi.org/10.1007/s00170-021-07340-8.
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AbstractFluid leakage from hydraulic cylinders is a major concern for the offshore industries as it directly affects hydraulic cylinder energy efficiency and causes environmental contamination. There have been attempts made in literature to develop robust condition monitoring techniques for hydraulic cylinders. However, most of these studies were performed to identify degradation of single components. Therefore, in this study, the aim is to monitor degradation of multiple components simultaneously in hydraulic cylinders using acoustic emissions. Experiments performed consist of three test phases and were performed using a hydraulic test rig. In the first test phase, the study is performed to identify acoustic emission features that can be used to monitor piston rod seal wear. In the second test phase, acoustic emission features are identified that can be used to understand bearing wear when unworn, semi-worn or worn piston rod seals are used in hydraulic test rig. In the third test phase, a run-to-failure test is conducted to identify acoustic emission features that can indicate fluid leakage initiation due to piston rod seal wear. The median frequency feature showed good repeatability in all the three test phases to identify piston rod seal wear, bearing wear and fluid leakage initiation during the initial stages in the hydraulic test rig. The proposed acoustic emission-based condition monitoring technique is robust and can be used for the hydraulic cylinders in the industries, as it identifies acoustic emission features based on particular frequency bands associated to specific components, making it less susceptible to noise from other components.
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Aliev, V. I., i I. I. Gasanov. "Improving the Sealing Efficiency of Compressor Cylinders of Gas Engine Compressors in the System of Gas-Lift Production of Offshore Fields". Проблемы машиностроения и надежности машин, nr 6 (1.11.2023): 96–101. http://dx.doi.org/10.31857/s0235711923060044.
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An increase in the efficiency of gland seals in compressor cylinders with cast iron rings pressed against the contact surface of the piston rod using a steel spring in reciprocating compressors used in offshore oil and gas-condensate fields for gas-lift oil production systems is considered. Studies of a gas engine reciprocating compressor working directly on the operating gas-lift system have shown that in order to increase the time of normal operation of gland seals, it is necessary to adjust the clearance using lubricant up to 0.1 mm. After increasing the spring stiffness, the serviceability and number of working hours of the gland seal increased twofold, from 850 to 1700 h.
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Popikov, P. I., V. I. Posmetjev i S. I. Fedjaev. "Improvement of V-ring seals in hydraulic cylinders of forest machines". Resources and Technology, nr 5 (2005): 87–89. http://dx.doi.org/10.15393/j2.art.2005.1978.
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KOSAKI, Takahiro, i Manabu SANO. "Measurement of Oil Film Pressure at Piston Seals in Pneumatic Cylinders". Transactions of the Society of Instrument and Control Engineers 37, nr 1 (2001): 89–91. http://dx.doi.org/10.9746/sicetr1965.37.89.
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Kandukuri, Surya T., Vignesh V. Shanbhag, Thomas J. J. Meyer, Leo W. Caspers, Nadia S. Noori i Rune Schlanbusch. "Automated and Rapid Seal Wear Classification Based on Acoustic Emission and Support Vector Machine". PHM Society European Conference 6, nr 1 (29.06.2021): 8. http://dx.doi.org/10.36001/phme.2021.v6i1.2942.
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Seal wear in hydraulic cylinders results in fluid leakage, and instability of the piston rod movement. Therefore, regular inspection of seals is required using automated approaches to improve productivity and to reduce unscheduled maintenance. In literature, successful attempts have been made using acoustic emission-based condition monitoring to classify the seal wear. However, limited attempts have been made to implement automated approaches to classify seal wear using acoustic emission features. Therefore, this article presents an automated approach for rapid and computationally economical diagnosis of seal wear using acoustic emission. The experiments were performed at varying pressure conditions on a hydraulic test rig that can simulate fluid leakage conditions similar to that of hydraulic cylinders. From the acoustic emission spectrum, the frequency bands were identified with peak power and by heterodyning the signal. This technique results in 10X downsampling without losing the information of interest. Further, the signal was divided into smaller “snapshots” to facilitate rapid diagnosis. In these tests, the diagnosis was made on short-time windows, as low as 0.3 seconds in length. A set of time and frequency domain features were designed, and the Support Vector Machine (SVM) was trained on 60 % of the test cases generated with seals of three different conditions. The SVM was able to accurately classify the status irrespective of the pressure conditions, with an accuracy of ~99 %. Therefore, the proposed automated seal wear classification technique based on acoustic emission and SVM can be used for real-time monitoring of seal wear in hydraulic cylinders.
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Yang, Junwei, Xin Sun, Hua Yang i Xiangjun Wang. "Experimental Study on Aerodynamic Characteristics of Downwind Bionic Tower Wind Turbine". Biomimetics 9, nr 6 (2.06.2024): 336. http://dx.doi.org/10.3390/biomimetics9060336.
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The vibrissae of harbor seals exhibit a distinct three-dimensional structure compared to circular cylinders, resulting in a wave-shaped configuration that effectively reduces drag and suppresses vortex shedding in the wake. However, this unique cylinder design has not yet been applied to wind power technologies. Therefore, this study applies this concept to the design of downwind wind turbines and employs wind tunnel testing to compare the wake flow characteristics of a single-cylinder model while also investigating the output power and wake performance of the model wind turbine. Herein, we demonstrate that in the single-cylinder test, the bionic case shows reduced turbulence intensity in its wake compared to that observed with the circular cylinder case. The difference in the energy distribution in the frequency domain behind the cylinder was mainly manifested in the near-wake region. Moreover, our findings indicate that differences in power coefficient are predominantly noticeable with high tip speed ratios. Furthermore, as output power increases, this bionic cylindrical structure induces greater velocity deficit and higher turbulence intensity behind the rotor. These results provide valuable insights for optimizing aerodynamic designs of wind turbines towards achieving enhanced efficiency for converting wind energy.
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Millward, J. A., i M. F. Edwards. "Windage Heating of Air Passing Through Labyrinth Seals". Journal of Turbomachinery 118, nr 2 (1.04.1996): 414–19. http://dx.doi.org/10.1115/1.2836657.
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The viscous drag on rotating components in gas turbine engines represents both a direct loss of power from the cycle and an input of heat into the secondary (cooling) air system. Hotter cooling air in turn means increased flow requirements. The effects of windage on performance are therefore compounded. To facilitate accurate temperature predictions of highly stressed components, information is needed on windage characteristics of all elements in the secondary cooling system. Much information is available in the literature for disks, cones, cylinders, bolts, etc., but little has been published on windage heating in high-speed seals. Results are presented for experiments carried out (at representative nondimensional conditions) on different designs of labyrinth seals. The results are compared with values calculated from the simple momentum balance theory suggested by McGreeham and Ko [13] and with several values determined from CFD analysis.
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Beem, Heather R., i Michael S. Triantafyllou. "Wake-induced ‘slaloming’ response explains exquisite sensitivity of seal whisker-like sensors". Journal of Fluid Mechanics 783 (16.10.2015): 306–22. http://dx.doi.org/10.1017/jfm.2015.513.
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Blindfolded harbour seals are able to use their uniquely shaped whiskers to track vortex wakes left by moving animals and identify objects that passed by 30 s earlier, an impressive feat, as the flow features have velocities as low as $1~\text{mm}~\text{s}^{-1}$. The seals sense while swimming, hence their whiskers are sensitive enough to detect small-scale changes in the flow, while rejecting self-generated flow noise. Here we identify and illustrate a novel flow mechanism, causing a large-amplitude ‘slaloming’ whisker response, which allows artificial whiskers with the identical unique undulatory geometry as those of the harbour seal to detect the features of minute flow fluctuations when placed within wakes. Whereas in open water the whisker responds with very low-amplitude vibration, once within a wake, it oscillates with large amplitude and, importantly, its response frequency coincides with the Strouhal frequency of the upstream cylinder, making the detection of an upstream wake and an estimation of the size and shape of the wake-generating body possible. This mechanism has some similarities with the flow mechanisms observed in actively controlled propulsive foils within upstream wakes and trout swimming behind bluff cylinders in a stream, but there are also differences caused by the unique whisker morphology, which enables it to respond passively and within a much wider parametric range.
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Czmerk, András J. "Increasing of Stiffness of Double-Acting Pneumatic Cylinder". Analecta Technica Szegedinensia 9, nr 1 (12.01.2015): 39–45. http://dx.doi.org/10.14232/analecta.2015.1.39-45.
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Position keeping properties of actuators depend highly on their stiffness. The low stiffness of pneumatic systems is well known, which is disadvantageous during positioning and when a position has to be kept. It is one of the reasons why hydraulic systems have advantages over pneumatic systems when it comes to positioning tasks. This paper deals with the analysis of the passive stiffness of a double-acting cylinder. The stiffness of pneumatic cylinders is derived as a function of chamber pressures determined by the bulk modulus of pneumatic systems. The stiffness of a passive system of the chambers is written by the pressure change through small displacement of the piston and as a result of the restoring force. In case of the passive system the effect of the valve actuation is neglected. From the deduction it is clear that the stiffness of a cylinder changes along the stroke, dead volumes at the end positions play a relatively important role. The results are compared with the restoring forces of the piston seals and other sealing elements in the stiction region. The restoring effects of the elastic elements were determined by measurements.
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Mohsen J. Joaij, Moneer H. Tlafeh, Esam T. Abdullah i Abdullah D. Assi. "Design And Manufacturing of a Hydrostatic Extrusion Apparatus for Compound Cylinders from AL And MG". Diyala Journal of Engineering Sciences 6, nr 2 (1.06.2013): 86–102. http://dx.doi.org/10.24237/djes.2013.06207.
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The purpose of this research is to design and construct an experimental hydrostatic extrusion apparatus which has a maximum working pressure of 500 bar, and to reduce the cost of this extrusion apparatus. The high-pressure extrusion container has been designed with hydraulic cylinders which is cheap and readily available. Different materials and designs for high-pressure seals were tested and analyzed for the best combination performance. Problems in the extrusion processes using this device were analyzed and solved, which increased the reliability of the device. The results of extrusion experiments have established that this device is practicable.
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Pedersen, Jørgen F., Rune Schlanbusch, Thomas J. J. Meyer, Leo W. Caspers i Vignesh V. Shanbhag. "Acoustic Emission-Based Condition Monitoring and Remaining Useful Life Prediction of Hydraulic Cylinder Rod Seals". Sensors 21, nr 18 (8.09.2021): 6012. http://dx.doi.org/10.3390/s21186012.
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The foremost reason for unscheduled maintenance of hydraulic cylinders in industry is caused by wear of the hydraulic seals. Therefore, condition monitoring and subsequent estimation of remaining useful life (RUL) methods are highly sought after by the maintenance professionals. This study aimed at investigating the use of acoustic emission (AE) sensors to identify the early stages of external leakage initiation in hydraulic cylinders through run to failure studies (RTF) in a test rig. In this study, the impact of sensor location and rod speeds on the AE signal were investigated using both time- and frequency-based features. Furthermore, a frequency domain analysis was conducted to investigate the power spectral density (PSD) of the AE signal. An accelerated leakage initiation process was performed by creating longitudinal scratches on the piston rod. In addition, the effect on the AE signal from pausing the test rig for a prolonged duration during the RTF tests was investigated. From the extracted features of the AE signal, the root mean square (RMS) feature was observed to be a potent condition indicator (CI) to understand the leakage initiation. In this study, the AE signal showed a large drop in the RMS value caused by the pause in the RTF test operations. However, the RMS value at leakage initiation is seen to be a promising CI because it appears to be linearly scalable to operational conditions such as pressure and speed, with good accuracy, for predicting the leakage threshold.
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Kozubková, Milada, Jana Jablonská, Marian Bojko, František Pochylý i Simona Fialová. "Multiphase Flow in the Gap Between Two Rotating Cylinders". MATEC Web of Conferences 328 (2020): 02017. http://dx.doi.org/10.1051/matecconf/202032802017.
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The research of liquids composed of two (or more) mutually immiscible components is a new emerging area. These liquids represent new materials, which can be utilized as lubricants, liquid seals or as fluid media in biomechanical devices. The investigation of the problem of immiscible liquids started some years ago and soon it was evident that it will have a great application potential. Recently, there has been an effort to use ferromagnetic or magnetorheological fluids in the construction of dumpers or journal bearings. Their advantage is a significant change in dynamic viscosity depending on magnetic induction. In combination with immiscible liquids, qualitatively new liquids can be developed for future technologies. In our case, immiscible fluids increase the dynamic properties of the journal hydrodynamic bearing. The article focuses on the stability of single-phase and subsequently multiphase flow of liquids in the gap between two concentric cylinders, one of which rotates. The aim of the analysis was to study the effect of viscosity and density on the stability/instability of the flow, which is manifested by Taylor vortices. Methods of experimental and mathematical analysis were used for the analysis in order to verify mathematical models of laminar and turbulent flow of immiscible liquids.
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Deaconescu, Tudor, i Andrea Deaconescu. "Experimental Research on Polymer-Based Coaxial Sealing Systems of Hydraulic Cylinders for Small Displacement Velocities". Polymers 14, nr 2 (11.01.2022): 290. http://dx.doi.org/10.3390/polym14020290.
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Reducing friction in the coaxial sealing systems of hydraulic cylinders is one of the solutions for increasing the energy efficiency of industrial actuations. This is a requirement, particularly in the case of small velocities that carry the risk of eigen-vibrations and/or stick-slip. The authors discuss the experimental research conducted on three coaxial sealing systems made from thermoplastic polymer and polyurethane type materials. The paper presents the equipment and method used for the experimental determination of static and kinematic friction coefficients and discusses the subsequent results obtained to test different working parameters. The experimentally determined friction coefficients yielded a range of materials recommended for coaxial seals such as to minimize the occurrence of jerky operation.
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Kim, D. T., i Z. J. Zhang. "The Friction Characteristics with Variation of Cross Section of Piston Seals for High Speed Pneumatic Cylinders". Journal of The Korean Society for Fluid Power & Construction Equipments 9, nr 1 (1.03.2012): 18–24. http://dx.doi.org/10.7839/ksfc.2012.9.1.018.
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Skowrońska, Justyna, Andrzej Kosucki i Łukasz Stawiński. "Overview of Materials Used for the Basic Elements of Hydraulic Actuators and Sealing Systems and Their Surfaces Modification Methods". Materials 14, nr 6 (15.03.2021): 1422. http://dx.doi.org/10.3390/ma14061422.
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The article is an overview of various materials used in power hydraulics for basic hydraulic actuators components such as cylinders, cylinder caps, pistons, piston rods, glands, and sealing systems. The aim of this review is to systematize the state of the art in the field of materials and surface modification methods used in the production of actuators. The paper discusses the requirements for the elements of actuators and analyzes the existing literature in terms of appearing failures and damages. The most frequently applied materials used in power hydraulics are described, and various surface modifications of the discussed elements, which are aimed at improving the operating parameters of actuators, are presented. The most frequently used materials for actuators elements are iron alloys. However, due to rising ecological requirements, there is a tendency to looking for modern replacements to obtain the same or even better mechanical or tribological parameters. Sealing systems are manufactured mainly from thermoplastic or elastomeric polymers, which are characterized by low friction and ensure the best possible interaction of seals with the cooperating element. In the field of surface modification, among others, the issue of chromium plating of piston rods has been discussed, which, due, to the toxicity of hexavalent chromium, should be replaced by other methods of improving surface properties.
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Nguyen, Thuy-Duong, i Van-Hung Pham. "Study of the effects of relative humidity and velocity on the friction characteristics of pneumatic cylinders". International Journal of Modern Physics B 34, nr 22n24 (25.08.2020): 2040139. http://dx.doi.org/10.1142/s0217979220401396.
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The movement of a piston rod in a pneumatic cylinder is directly affected by the air humidity in the atmosphere, especially in the case of piston rods without any means of protection or grease on their surfaces. In a pneumatic cylinder system, the friction between the piston rod and the rod seal is sliding friction, and it has a significant value that varies with the variation in the moisture on the piston rod’s surface. In this paper, an investigation of the friction characteristics of piston rods and rod seals in a pneumatic cylinder was carried out with different humidity and velocity values to understand the effect of lubricants on the moving parts of pneumatic systems in humid environments, where the friction characteristics of the displacements corresponding to the static and dynamic friction forces were displayed on a measuring device. The research results showed that the static friction forces tended to decrease by [Formula: see text] and that the dynamic friction forces tended to decrease by [Formula: see text] when the relative humidity increased from 51% to 99% at different velocities between 5 and 100 mm/s.
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Aliyev, Alesker M. "Determination of kinematic parameters of the compressor unit applied to low-pressure petroleum gas". Nafta-Gaz 79, nr 4 (kwiecień 2023): 252–56. http://dx.doi.org/10.18668/ng.2023.04.03.
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The collection and transportation of low-pressure gas released into the atmosphere from the oil fields is important in increasing gas production. This issue, which differs in its actuality, has both economic and pollution preveniton benefits. One such project, led by the UN Development Fund, was successfully implemented in the city of Siyazan, Azerbaijan. An electrically driven compressor unit of NQK-7/1-5 type with two oscillating cylinders is commonly used for such work. On visual inspection of the compressors undergoing repair, it was found that the seals in the pneumatic part and the elements of the cylinder-piston group are completely out of order, the gear teeth in the transmission part are broken, worn, the bearings are destroyed, the belts are torn, etc. Compressors sent for repair are almost always reassembled. A structural-kinematic analysis of the compressor installation was carried out to find out the causes of the existing malfunctions. For this purpose, a kinematic diagram of the conversion mechanism of the compressor – a slider-crank linkage mechanism was drawn up using the method of closed contours from projection equations relative to the X and Y axes, and based on the condition that the rotation angles of the piston and cylinder axes are equal, the instantaneous rotation angle, angular velocity and angular acceleration of the cylinder rotation, as well as instantaneous values of displacement, speed and acceleration of the piston inside the cylinder were found. It was shown that the designer's decision on the selection of the design scheme and determination of the product dimensions, which are one of the main issues in the design of the mechanism, should be made based on the results of the kinematic and dynamic analysis.
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Alisin, V. V., M. N. Roshchin i A. I. Lukyanov. "Enhancing the tribological properties of fluoroplastics operating in a hydraulic fluid environment". E3S Web of Conferences 458 (2023): 08025. http://dx.doi.org/10.1051/e3sconf/202345808025.
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The issues of an increasing the wear resistance of fluoroplastics under conditions of dry friction against steel and in the environment of hydraulic fluids are discussed in this article. The statement about the prospects of radiation treatment for strengthening fluoroplastics is substantiated. Comparative tribological tests were carried out on a laboratory friction machine according to the friction scheme of the end of a cylindrical sample made of steel 40X13 on a fluoroplastic plate. It has been established that radiation-modified fluoroplastic has increased wear resistance. The antifriction properties of strengthened fluoroplastic during friction in a hydraulic fluid environment are investigated. The influence of load and speed on the friction coefficient is analyzed. Based on the study, a radiation modification of fluoroplastic rod seals of hydraulic cylinders and hydraulic piston machines is proposed, with a possible increase in wear resistance up to 4 times.
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Valdiero, Antonio Carlos, Carla Silvane Ritter, Cláudio Fernando Rios i Marat Rafikov. "Nonlinear Mathematical Modeling in Pneumatic Servo Position Applications". Mathematical Problems in Engineering 2011 (2011): 1–16. http://dx.doi.org/10.1155/2011/472903.
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This paper addresses a new methodology for servo pneumatic actuators mathematical modeling and selection from the dynamic behavior study in engineering applications. The pneumatic actuator is very common in industrial application because it has the following advantages: its maintenance is easy and simple, with relatively low cost, self-cooling properties, good power density (power/dimension rate), fast acting with high accelerations, and installation flexibility. The proposed fifth-order nonlinear mathematical model represents the main characteristics of this nonlinear dynamic system, as servo valve dead zone, air flow-pressure relationship through valve orifice, air compressibility, and friction effects between contact surfaces in actuator seals. Simulation results show the dynamic performance for different pneumatic cylinders in order to see which features contribute to a better behavior of the system. The knowledge of this behavior allows an appropriate choice of pneumatic actuator, mainly contributing to the success of their precise control in several applications.
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Shuster, Mark, i Mick Deis. "Characterization of triological sealing system components using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS)". Proceedings, annual meeting, Electron Microscopy Society of America 54 (11.08.1996): 184–85. http://dx.doi.org/10.1017/s0424820100163381.
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A system approach to solving the tribological problems associated with sealing joints implies comprehensive investigation of all the components. To recognize the root cause of any problem and formulate the required performance for extended reliability we have to evaluate any changes in the system as quantitatively as possible. Any measurable parameters, including geometry, density (porosity), hardness distributions, microstructure and grain size changes observed during routine metallurgical analysis could provide evidence of the root cause of failure. In the head-gasket-block sealing system of the internal combustion engine, the EDS evaluation of the chlorine and sulfur distribution through the head gasket flange fracture in conjunction with analysis of the sludge between the head, block and gasket surfaces pointed to the corrosive nature of the gasket flange cracking.This approach is even more useful for the closed tribological system of telescopic hydraulic cylinders or rotary axle shaft oil seals.
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Elmardi Suleiman, Dr Osama Mohammed, i Mansour Hamad Elmamoun. "A REVIEW STUDY IN TROUBLESHOOTING OF HYDRAULIC SYSTEMS IN CEMENT INDUSTRIES". International Journal of Engineering Applied Sciences and Technology 7, nr 8 (1.12.2022): 62–82. http://dx.doi.org/10.33564/ijeast.2022.v07i08.006.
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Behind every hydraulic system there exists critical components that influence power transmission. To improve talent you should recognize how these components operate and affect the system i.e. learn the kinds of filter and piping used in hydraulic systems, describe the types and functions of hydraulic seals, and explain the operating principles of different types of pumps, and further learning the types and uses of accumulators, control valves, relief valves, cylinders, and even actuators. In this research study appropriate problem-solving processes are applied, and this helps to comprehend the hydraulic concepts and hydraulic schematic representations. Therefore, it will enhance the knowledge and the capacity of troubleshooting the different hydraulics systems in the cement industry. This will enable the person to stay on top of the industry practices in hydraulics, explore the basics of a hydraulic system by reviewing the types and properties of hydraulic fluids, identifying the symbols used on hydraulic schematic representations, and explaining hydraulic circuit operations based on a schematic design.
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Chernousenko, O. Yu, L. S. Butovskyi, T. V. Nikulenkova i I. S. Bednarska. "BOUNDARY CONDITIONS OF HEAT EXCHANGE IN THE LACE SEALS OF CYLINDERS OF HIGH AND LOW PRESSURE OF TURBINE K-1000-60 / 3000". Electrical Engineering and Power Engineering, nr 2 (31.07.2018): 16–26. http://dx.doi.org/10.15588/1607-6761-2018-2-2.
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Popikov, P., Denis Kanishchev i A. Sutolkin. "RESULTS OF EXPERIMENTAL RESEARCHES OF WORKING PROCESSES OF BLOCKLESS LOGGING CAPTURE WITH ENERGY-SAVING HYDRAULIC DRIVE". Actual directions of scientific researches of the XXI century: theory and practice 8, nr 1 (26.10.2020): 123–28. http://dx.doi.org/10.34220/2308-8877-2020-8-1-123-128.
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During the movement of the tractor in the unit with the lockless grabs on the roughness of the terrain on the cuttings there are fluctuations that cause jumps of the working fluid in the hydraulic system. This leads to loss of fluid through the gaps and seals of the moving elements of the pump and hydraulic cylinders. For laboratory studies of these phenomena, a laboratory installation was made with the introduction of a pneumatic-hydraulic accumulator of the A5579-0 series into the hydraulic circuit. Laboratory tests were carried out, which showed that the pneumohydraulic battery allows, due to the energy accumulated during operation, to reduce the pressure spikes of the working fluid in the hydraulic system. This reduces the dynamic load on the metal structure of the grip, the hydraulic pump drive and the tractor transmission, as well as increases the volumetric efficiency. After processing waveforms of operating modes to capture with energy saving hydraulic drive using the program STATISTICA was established replications of individual load magnitudes and histograms of pressure without the use of a hydropneumatic accumulator and to its use. It was found that the energy recovery system reduces the pressure spikes of the working fluid during transients by 1.4-1.7 times and allows you to store power within 1.7 ... 2.1 kW.
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Tillett, N. D., N. D. Vaughan i A. Bowyer. "A non-linear model of a rotary pneumatic servo system". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 211, nr 2 (1.03.1997): 123–33. http://dx.doi.org/10.1243/0959651971539948.
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A simulation model of a rotary pneumatic servo system has been developed and verified against an experimental system. The double-acting rotary actuator is a novel device utilizing flexible inflatable bladders. The device differs from conventional pneumatic cylinders in that it exhibits low levels of friction, as it has no sliding seals, but it does suffer from hysteresis caused by bladder distortion. The objective of this study was to develop a tool with which to investigate the effect of various forms of hysteresis and other parameters on system performance. The dynamic model utilizes a linearized analysis of pneumatic components based on earlier studies. The principal advance described in this paper relates to the inclusion of non-linear elements. These are hysteresis caused by friction or the distortion of flexible components, and a digital controller implementation. The simulation successfully predicted all major modes of behaviour. Simplified models of rubber and coulomb friction-induced hysteresis modified simulation performance in line with experimental results. An investigation in simulation showed that coulomb friction-induced hysteresis had a greater damping effect than that caused by distorting the bladders. This result applies only to position control, as hysteresis has been shown not to provide damping in trajectory control applications.
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Herr, Marin, F. Xavier Borras, Dirk Spaltmann, Mirco Kröll, Franz Pirker i Ulrike Cihak-Bayr. "How to Create Trusted Tribological Characterization Data of Soft Polymers as Input for FEM Simulations?" Materials 16, nr 1 (23.12.2022): 131. http://dx.doi.org/10.3390/ma16010131.
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Soft polymers such as the investigated polyurethane, characterized by low Young’s moduli and prone to high shear deflection, are frequently applied in pneumatic cylinders. Their performance and lifetime without external lubrication are highly determined by the friction between seal and shaft and the wear rate. FEM simulation has established itself as a tool in seal design processes but requires input values for friction and wear depending on material, load, and velocity. This paper presents a tribological test configuration for long stroke, reciprocating movement, allowing the generation of data which meet the requirements of input parameters for FEM simulations without the geometrical influences of specific seal profiles. A numerical parameter study, performed with an FEM model, revealed the most eligible sample geometry as a flat, disc-shaped sample of the polymer glued on a stiff sample holder. At the same time, the study illustrates that the sensitivity of the contact pressure distribution to Poisson’s ratio and CoF can be minimized by the developed and verified setup. It ensures robust, reliable, and repeatable experimental results with uniform contact pressures and constant contact areas to be used in databases and FEM simulations of seals, enabling upscaling from generically shaped samples to complex seal profiles.
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Конох, Владимир Иванович, Игорь Иванович Калиниченко, Иван Николаевич Гордиец i Василий Васильевич Миколаевский. "ВИЗНАЧЕННЯ КОЕФІЦІЄНТУ КОРИСНОЇ ДІЇ ДВОКОМПОНЕНТНОГО ПНЕВМОНАСОСНОГО АГРЕГАТУ ДЛЯ КОСМІЧНОГО АПАРАТА". Aerospace technic and technology, nr 7 (10.11.2018): 12–19. http://dx.doi.org/10.32620/aktt.2018.7.02.
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Research has been carried out to determine the efficiency of the piston pneumatic pump unit (PPU) of two-way action for the fuel supply system of a spacecraft operating on propellants of AT and MMH (UDMH). The PPU relates to volumetric pumps, therefore, the efficiency is defined as the ratio of effective work performed by the PPU to the expended gas work. The range of total propellants flow rates from 100 to 240 g/s through the PPU is determined by the operating modes of main engine and steering thrusters. As a result of performed researches, the PPU efficiency and main factors influencing on its value were theoretically determined, namely: gas losses for filling "parasitic" volumes including the volumes that do not participate in the process of fluid displacement from hydraulic pumps (volumes associated with incomplete fit of the pneumatic pistons to the bottoms of the pneumatic cylinders, the volume of control and supply channels), but are ejected into the environment at each operation of the PPU pneumatic distributor together with the volume of gas that performed effective work; gas ejections through the drainage seats into the environment at pneumatic distributors switchings, since at pneumatic distributors switchings some cavities are connected with the power supply source by control pressure, and other ones - with environment by poppet moving from the feed seat to the drainage seat; inlet air (helium) pressure losses due to the resistance of gas channels of the pneumatic distributors; friction of seals with fluoroplastic collars of the piston blocks; resistance of the hydraulic channels which components are: pressure losses of non-return valves and hydraulic channels; displaced fluid volume decreasing by hydraulic pumps due to leakage of non-return valves, piston collars and hydraulic pumps rods. The bipropellant PPU efficiency was theoretically and experimentally determined at different operating modes. The calculated value of the efficiency is well confirmed by experiments at that the divergence does not exceed 4%. The results of this research will allow us to determine the necessary gas reserves on board of spacecraft at the stage of designing.
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Yang, Yi, Hu Huang i Ji Chang Wang. "Design of Strength of the Seats and Head Restraints Testing System". Applied Mechanics and Materials 48-49 (luty 2011): 397–400. http://dx.doi.org/10.4028/www.scientific.net/amm.48-49.397.
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designed a equipment for testing the strength of seats and head restraints, the equipment can testing the seats and head restraints with the standard of GB 11550-1995 5.2. The equipment was composed of one upper cylinder elevating system, a beam elevating system, two load cylinders and a hydraulic station. In addition to designed the principle of the hydraulic system.
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Cao, Yuanguo, i Xudong Dai. "Modeling for performance degradation induced by wear of a hydraulic actuator of a hydraulic excavator". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, nr 3 (15.05.2014): 556–65. http://dx.doi.org/10.1177/0954406214535926.
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As an index of maintaining low fuel consumption, the digging force of an excavator is affected fully by the performance of the hydraulic actuators including boom cylinder, stick cylinder, and bucket cylinder. The seals are used widely in a fluid power system to prevent fluid leakage. However, wear induces changes in the diameter of the seal's cross-section area, having an effect on the sealing capability of seals. This article proposes a model for performance degradation induced by wear of a hydraulic actuator of an excavator. The model in this article describes the physical process of performance degradation of a hydraulic actuator by analyzing piston response when wear occurs. The model includes a dynamic model of a hydraulic actuator, a model of squeezing stress and deformation of a compressed elastomeric O-ring seal, a wear model of a seal, and a leak rate model. These models can be used for deducing the laws of performance degradation of a hydraulic actuator of an excavator and for predicting the useful life of a key component such as the seal. Finally, based on the established model, simulation results of a hydraulic actuator’s response are provided.
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Wu, Jian, Hang Luo, Haohao Li, Benlong Su, Youshan Wang i Zhe Li. "The Influence of Hydrothermal Aging on the Dynamic Friction Model of Rubber Seals". Polymers 12, nr 1 (4.01.2020): 102. http://dx.doi.org/10.3390/polym12010102.
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Cylinder has become an indispensable and important pneumatic actuator in the development of green production technology. The sealing performance of the cylinder directly affects its safety and reliability. Under the service environment of the cylinder, hydrothermal aging of the rubber sealing ring directly affects the dynamic friction performance of the cylinder. So, the dynamic friction model of the cylinder has been developed based on the LuGre friction model, which considers the influence of hydrothermal aging. Here, the influences of the static friction coefficient and Coulomb friction coefficient on the friction model are analyzed. Then, the aging characteristic equation of rubber is embedded in the model for revealing the influence of aging on the friction coefficient of the model. Results show that the aging temperature, aging time, and compressive stress affects the friction coefficient; the variation of the static friction coefficient is larger than that of the Coulomb friction coefficient. The improved cylinder friction model can describe the influence of the aging process on the cylinder friction characteristics, which is of great significance in the design of the cylinder’s dynamic performance.
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YAZGIN, Yücel. "ANALYSIS OF CYPRUS ARCHEOLOGICAL CYLINDER SEAL VISUALS". EUROASIA JOURNAL OF SOCIAL SCIENCES & HUMANITIES 8, nr 3 (25.05.2021): 10–26. http://dx.doi.org/10.38064/eurssh.153.
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People have tried to determine their "personality" and "property" rights by using special signs and symbols since ancient times. These symbols are the signs that people who lived together and formed a community in the conditions of that day that they agreed on. One of the human-made tools, on which these special personality and property markers appear are cylinder seals. Different expressions were made besides determining personality and property by means of text and images engraved on cylinder seals. In this research, cylinder seals, which are archaeological artifacts in the island of Cyprus, exhibited in museums and may be subject to the relevant literature were examined. The seals that make up the sample consist of cylinder seals exhibited in Cyprus archaeological museums, in the British Museum, Metropolitan Museum and the Cyprus artifacts sections of the John Hopkins Museum. The cylinder seals used by the communities and governments that have dominated Cyprus in the historical process have been investigated as visual imagery. Therefore, images on cylinder seals produced in Cyprus or neighbouring cultures between 2000 BC and 600 BC were investigated. In this research, the engravings on seals that were produced in neighbouring cultures and brought to Cyprus as a gift or were imported also examined. All figures made on the seals were produced in neighbouring cultures and brought to the island with different methods were also included in the study. In this context, the features of the motif, figure, inscription, decoration and patterns used on 191 cylinder seals obtained during the research process were investigated. As a result of the examination, figures which engraved on the seals was coded in accordance with their themes, all the images engraved on the seals were divided into categories. Six main categories were determined as a result of categorical division. Twenty-seven themes belonging to the identified main six categories were also determined. Among the scrapings on the cylinder seals that constitute the sample of the research; visuals that determine the variety of food production, agriculture, mining, blessing and sacrifice scenes, and demonstrating the scenes of a birthday of the seal owner were encountered. From the pictures drawn on the cave walls, it is known that such special signs or images serving different purposes were used. In this context, the fact that only pictorial images were engraved on some of the cylinder seals reveals the view that they existed before the writing and that the tradition of that period continued on the seal engraving after the writing was found.