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In order to relieve the problem of bearing wear in high-speed permanent magnet generator, a semi-symmetrical double winding structure with the same number of poles is proposed in this paper. The coupling of the winding magnetic fields enables the rotor to be subjected to a radial electromagnetic force along the direction of overcome gravity, which could effectively extend the service life of the bearings. Firstly, the design principle of the semi-symmetrical double winding structure and the winding MMF are analyzed based on the AC machine winding theory, and the elliptical magnetic field characteristics of the harmonic winding are clarified. Combining the characteristics of order and frequency for harmonic magnetic field, the magnetic fields coupling mechanism of the double winding is revealed, and the analytic model of the power generation and radial electromagnetic force are determined. Secondly, based on rolling contact fatigue theory, the service life improvement of bearing by the double winding structure is certificated. In addition, the magnetic fields of double winding are decoupling calculated by using the finite element method, and the consistency of results between the theoretical analyses and the finite element calculations is determined. Finally, the calculation accuracy of the finite element analysis is demonstrated by experiments on the prototype. [ABSTRACT FROM AUTHOR]

Sliding bearings are a vulnerable component of bridges. Bearing wear will affect the free expansion of the bridge structure and produce greater temperature stress, resulting in damage to the main girder and other components of the bridge. In the process of bridge operation, the timely detection of bearing wear is very important for ensuring structural safety. Therefore, this paper proposes a wear detection method for bridge sliding bearings based on displacement amplitude by eliminating the effects of daily temperature variations. First, the bearing mechanical behavior under temperature effects and the correlation between temperature and bearing friction force are analyzed. The bearing displacement hysteresis model under temperature effects is established, and the variation in thermally induced bearing displacement after wear is obtained. Then, the correlation between temperature and thermally induced bearing displacement is analyzed and, based on the particle swarm optimization (PSO) algorithm and long short-term memory (LSTM) neural network, a multivariate temperature–displacement correlation model is established to achieve the accurate prediction of thermally induced bearing displacement and the elimination of temperature effects. According to the variation in the thermally induced displacement of the bearing after wear, the indicator of thermally induced displacement amplitude errors (TDAE) is proposed, and the cumulative sum (CUSUM) control chart is used to detect the bearing anomaly. Finally, a long-span bridge is analyzed as an example. The results show that the proposed TDAE detection indicator can effectively reflect the sliding friction force of the bridge bearing, and the proposed detection method can accurately detect the sliding bearing wear, which can provide effective information for the bridge caretakers to monitor the occurrence of bearing wear and replace the bearing slide plate in a timely manner. [ABSTRACT FROM AUTHOR]

The article presents the results of experimental studies on the effect of circulation pump operating modes on the wear of a double reciprocating slit throttling hydrostatic bearing operating in a lead coolant environment. The experiments were conducted on a high-temperature circulation test bench at a lead coolant temperature of 420–450°C. Results were obtained for operation modes with a high number of start-stop cycles (approximately 100 cycles per 100 h of operation), sustained operation with a low number of start–stop cycles and nominal speeds of 1000–1100 rpm (not exceeding 8 cycles per 100 h of operation), with 25 start–stop cycles per 100 h, and at low pump speeds below nominal values of 600–700 rpm with a maximum of 8 start–stop cycles per 100 h of operation. Data on the wear of the bearing bush and shaft are presented in the article. Processing and analysis of the research results led to the conclusion that this type of bearing can be used in low-pressure axial pump systems only under conditions where the pump creates a head exceeding 1.1 m of liquid lead. [ABSTRACT FROM AUTHOR]

Wear usually occurs in the loaded part of hydrodynamic bearings and leads to bearing geometry imperfections. This paper investigates the effects of wear-induced geometric imperfections of tilting pad journal bearings (TPJBs) on the dynamic behavior of the system. Furthermore, the effect of wear on the journal-bearing rub-induced contact pressure severity is investigated. A novel tribo-dynamic model is proposed for a flexible rotor-worn TPJB which integrates a mixed elastohydrodynamic model with a rotor-worn TPJB thermal and dynamic model to assess the effects of the bearing wear progression on rotor-TPJB behavior. Based on the results, wear changes the temperature distribution of the pads and oil film as well as the dynamic behavior of the system. Dynamic simulations reveal a higher vibration level and contact pressure for the worn TPJBs near the system's critical speed and service speed. Finally, thermal and dynamic condition indicators are suggested to detect TPJB wear severity at its early stages. [ABSTRACT FROM AUTHOR]

The work is devoted to the problem of bearings wear control of during their operation. Well-known methods for control the state of bearings to solve this problem are described. The use of the technology of identification measurement of signals to control the degree of wear of bearings is considered.

An expanding pin locks the pin assembly to its supports and bearings and prevents any relative movements between the surfaces in contact. In this study, the diameter changes of the bearing inner ring as a function of the expanding pin’s tightening torque were studied. In addition, the required rotational moment of a set of complete bearings locked to an expanding pin solution was studied by exposing the assembly to a combination of an increasing radially outwards directed load from the bolt torquing and a radially external inwards directed load from a hydraulic jack. The bearings were of type Radial Spherical Plain Bearings (RSPBs), GE 80 ES, steel/steel, and loaded externally up to their maximum dynamic limit of 400 kN. The results indicate a major reduction in the required rotation moment of the bearing when the bearing inner ring is expanded by use of an expanding pin. The reduction of rotation moment indicates reduced contact pressure and friction force between the two bearing rings, which ultimately can have a reduced effect on ring surface wear and a positive effect on the bearing operational lifetime.

Taking the rotor system supported by angular contact ball bearing as the research object, the dynamic model of rotor bearing system is established by using Lagrange equation. Based on the Archard wear model, the calculation model of wear depth of bearing raceways considering lubrication effects is presented. The wear depth is introduced into the system dynamics model as the bearing clearance. The dynamic characteristics of rotor-bearing system and the evolution of bearing wear are carefully analyzed taking into account the rotor speed, bearing preload and disc position. The results show that the influence of bearing wear on dynamic characteristics of rotor-bearing system is closely related to rotor speed and bearing preload. Changing disc position does not lead to the significant variation of dynamic characteristics of rotor-bearing system with wear depth of bearing raceways. The rotor speed significantly affects the bearing wear, the bearing preload has very limited effect on bearing wear, and the variation of the disc position results in the weak difference of wear depth of bearings.

This study compares the performance of a plain bearing, with a similar structure to a tail shaft stern bearing, lubricated with either mineral oil or an environmentally acceptable lubricant (EAL). The main characteristic of the bearing is its length/diameter ratio of

Helicopter rotor dynamics (blade vibrations, ground resonance, influence of forward speed, etc.) play an important role in the wear and tear of the transmission system and power unit. Particularly fast wear of these components is to be expected in military helicopters in combat conditions, where the flight dynamics parameters are often exceeded. The FAM-C method developed at the Air Force Institute of Technology in Poland has been used to assess and monitor this wear. This method can be used to monitor damage to helicopter propulsion and transmission, where other "classical" methods are less effective due to a very complicated system of forces, variable as to the direction of amplitude and frequency, causing vibrations in closely spaced kinematic pairs. For this reason, vibroacoustic and thermal effects are created around these kinematic pairs, which interfere with each other. In a helicopter, the propulsion unit, including the power transmission unit, is at the same time the carrier unit. This has forced designers to construct a propulsion system with a much greater number of joints and bearing supports. This article presents the possibilities of the FAM-C method for monitoring of swash-plate main bearing wear.

Wear usually occurs in the loaded part of hydrodynamic bearings and leads to bearing geometry imperfections. This paper investigates the effects of wear-induced geometric imperfections of tilting pad journal bearings (TPJBs) on the dynamic behavior of the system. Furthermore, the effect of wear on the journal-bearing rub-induced contact pressure severity is investigated. A novel tribo-dynamic model is proposed for a flexible rotor-worn TPJB which integrates a mixed elastohydrodynamic model with a rotor-worn TPJB thermal and dynamic model to assess the effects of the bearing wear progression on rotor-TPJB behavior. Based on the results, wear changes the temperature distribution of the pads and oil film as well as the dynamic behavior of the system. Dynamic simulations reveal a higher vibration level and contact pressure for the worn TPJBs near the system’s critical speed and service speed. Finally, thermal and dynamic condition indicators are suggested to detect TPJB wear severity at its early stages.

An expanding pin locks the pin assembly to its supports and bearings and prevents any relative movements between the surfaces in contact. In this study, the diameter changes of the bearing inner ring as a function of the expanding pin's tightening torque were studied. In addition, the required rotational moment of a set of complete bearings locked to an expanding pin solution was studied by exposing the assembly to a combination of an increasing radially outwards directed load from the bolt torquing and a radially external inwards directed load from a hydraulic jack. The bearings were of type Radial Spherical Plain Bearings (RSPBs), GE 80 ES, steel/steel, and loaded externally up to their maximum dynamic limit of 400 kN. The results indicate a major reduction in the required rotation moment of the bearing when the bearing inner ring is expanded by use of an expanding pin. The reduction of rotation moment indicates reduced contact pressure and friction force between the two bearing rings, which ultimately can have a reduced effect on ring surface wear and a positive effect on the bearing operational lifetime. [ABSTRACT FROM AUTHOR]

Condition monitoring of components in internal combustion engines is an essential tool for increasing engine durability and avoiding critical engine operation. If lubrication at the crankshaft main bearings is insufficient, metal-to-metal contacts become likely and thus wear can occur. Bearing temperature measurements with thermocouples serve as a reliable, fast responding, individual bearing-oriented method that is comparatively simple to apply. In combination with a corresponding reference model, such measurements could serve to monitor the bearing condition. Based on experimental data from an MAN D2676 LF51 heavy-duty diesel engine, the derivation of a data-driven model for the crankshaft main bearing temperatures under steady-state engine operation is discussed. A total of 313 temperature measurements per bearing are available for this task. Readily accessible engine operating data that represent the corresponding engine operating points serve as model inputs. Different machine learning methods are thoroughly tested in terms of their prediction error with the help of a repeated nested cross-validation. The methods include different linear regression approaches (i.e., with and without lasso regularization), gradient boosting regression and support vector regression. As the results show, support vector regression is best suited for the problem. In the final evaluation on unseen test data, this method yields a prediction error of less than 0.4 °C (root mean squared error). Considering the temperature range from approximately 76 °C to 112 °C, the results demonstrate that it is possible to reliably predict the bearing temperatures with the chosen approach. Therefore, the combination of a data-driven bearing temperature model and thermocouple-based temperature measurements forms a powerful tool for monitoring the condition of sliding bearings in internal combustion engines. [ABSTRACT FROM AUTHOR]

Introduction/purpose: The paper presents the application of modern methods in the diagnostics of sliding bearings and the analysis of influencing factors that can cause errors in such an application. Possibilities to determine with certainty when and where problems affect sliding bearings during system operation are presented. It is also shown how the system will continue to function over time. Causes of failures and the manner of their elimination are predicted, as well as the time for planned maintenance of technical systems. Method: The new method solves the problem of sliding bearing diagnostics by measuring the dynamic trajectories of the sleeve in the sliding bearing and by measuring vibration parameters on the inner and outer surfaces of the technical system. The dynamic trajectories of the bearing sleeve are measured with non-contact probes; therefore, the centering of probes in relation to the geometric center of the bearing is very important. Vibration parameters, directly related to the clearance in the sliding bearing, are measured on the inner and outer surfaces of the system. The choice of vibration parameters and measuring points is very important. This method has a number of advantages over other diagnostic methods, as it is easy to access measuring points. Results: By measuring the dynamic trajectory of the sleeves in the plain bearing and vibration parameters on the inner and outer surfaces, the bearing clearance quantities are determined, including: normal condition, initial clearance size, its further increase, bearing clearance sizes, and the moment when the condition parameters are close to the upper limit of the permissible bearing clearance. Conclusion: New diagnostic methods and monitoring systems can be widely applied to: internal combustion engines, all piston machines, hydroelectric power plants, thermal power plants, processing plants, and many other systems.

Introduction/purpose: The purpose of this paper is to present the importance of applying a new diagnostic method with a monitoring system and its capability to reliably determine when and where the problem will occur related to the wear of plain bearings in further operation of the plant, to offer a quality assessment of how the system will continue to function over time, to predict causes of failures and how to eliminate them as well as to provide time for planned maintenance of technical systems. Method:The new method solves the problem of sliding bearing diagnostics by measuring the dynamic trajectories (orbit) of the sleeve in the sliding bearing. Modern methods of technical diagnostics based on the measurement of dynamic parameters and electrical quantities and their analysis enable the support of measuring systems and measurement sensors from different manufacturers. Results: Measurements of the dynamic trajectories of sleeves in sliding bearings determine the values characterizing: normal condition, initial clearance size, further clearance increase, bearing clearance sizes, the moment when the state parameters are close to the upper limit of the allowable clearance, and the specific clearance size when further plant exploitation can cause system failure. Conclusion: The new diagnostic method and monitoring systems can be widely applied in all technical fields: internal combustion engines, hydroelectric power plants, thermal power plants, process plants, and in many other areas. Many monitoring systems, compatibility of devices and equipment of different manufacturers are supported by hardware and software. The calculations of theoretical and experimental dynamic parameters were verified. The method has a wide range of possibilities of application. / Введение/цель: Цель данной статьи заключается в представлении важности применения нового метода диагностики и системы мониторинга, возможности надежного определения времени и точного места возникновения проблемы, связанной с износом подшипников скольжения при дальнейшей эксплуатации установки, а также качественного прогноза при продолжении работы системы с течением времени, предусмотрение причин отказа и способов их устранения, а также планировки регулярного технического обслуживания системы. Метод: Новый метод решает проблему диагностики подшипников скольжения путем измерения траекторий перемещения (орбита) вала в подшипнике скольжения. Современные методы технической диагностики, основанные на измерении динамических параметров и электрических величин и их анализе позволяют поддерживать измерительные системы и датчики от различных производителей. Результаты: Измеряя траектории передвижения (орбиты) валов в подшипниках скольжения, определяется значения, которые характеризуют: нормальное состояние, начальную величину зазора, его дальнейшее увеличение, величину зазора подшипника, когда параметры приближаются предельно допустимой величине зазора и определяется величина зазора, в случае если дальнейшая эксплуатация установки может привести к отказу системы. Вывод: Новый метод диагностики и системы мониторинга может иметь широкое применение во всех технических областях, таких как: двигатели внутреннего сгорания, гидроэлектростанции, тепловые электростанции, технологические установки и пр. Аппаратное и программное обеспечение поддерживает множество систем мониторинга, контроля совместимости устройств и оборудования от разных производителей. Проведена верификация расчета теоретических и экспериментальных динамических параметров. Метод имеет широкий спектр применения. / Uvod/cilj: U radu je predstavljena primena nove dijagnostičke metode i monitoring sistema. Prikazana je mogućnost da se pouzdano utvrdi kada i gde će se pojaviti problem koji se javlja pri trošenju kliznih ležajeva u daljoj eksploataciji postrojenja. Pored toga, ocenjuje se kako će sistem nastaviti da funkcioniše tokom vremena, predviđaju se uzroci kvarova i način njihovog otklanjanja, kao i vreme za plansko održavanje tehničkih sistema. Metoda: Nova metoda rešava problem dijagnostike kliznih ležajeva merenjem dinamičkih putanja rukavca u kliznom ležaju. Savremene metode tehničke dijagnostike, zasnovane na merenju dinamičkih parametara i električnih veličina i njihove analize, omogućavaju podršku mernih sistema i senzora za merenje raznih proizvođača. Rezultati: Merenjem dinamičkih putanja (trajektorije) rukavaca u kliznim ležajima utvrđuju se veličine koje karakterišu: normalno stanje, početnu veličinu zazora, njegovo dalje povećavanje, veličine zazora ležaja, kada su parametri stanja blizu gornje granice dozvoljenog zazora, i utvrđivanje veličine zazora kada dalja eksploatacija postrojenja može prouzrokovati havariju sistema. Zaključak: Nova dijagnostička metoda i monitornig sistema mogu se široko primeniti u svim tehničkim oblastima: motorima sa unutrašnjim sagorevanjem, hidroelektranama, termoelektranama, procesnim postrojenjima i mnogim drugim oblastima. Hardverski i softverski podržavaju se mnogi sistemi za nadgledanje i proverava kompatibilnost uređaja i opreme raznih proizvođača. Izvršena je verifikacija proračuna teorijskih i eksperimentalnih dinamičkih parametara. Metoda ima široke mogućnosti primene.

Helicopter rotor dynamics (blade vibrations, ground resonance, influence of forward speed, etc.) play an important role in the wear and tear of the transmission system and power unit. Particularly fast wear of these components is to be expected in military helicopters in combat conditions, where the flight dynamics parameters are often exceeded. The FAM-C method developed at the Air Force Institute of Technology in Poland has been used to assess and monitor this wear. This method can be used to monitor damage to helicopter propulsion and transmission, where other "classical" methods are less effective due to a very complicated system of forces, variable as to the direction of amplitude and frequency, causing vibrations in closely spaced kinematic pairs. For this reason, vibroacoustic and thermal effects are created around these kinematic pairs, which interfere with each other. In a helicopter, the propulsion unit, including the power transmission unit, is at the same time the carrier unit. This has forced designers to construct a propulsion system with a much greater number of joints and bearing supports. This article presents the possibilities of the FAM-C method for monitoring of swash-plate main bearing wear. The swash-plates are not formally part of the helicopter's propulsion unit but are used to direct the thrust vector of the blades i.e., they direct the helicopter's power vector. Since during this process their components are observable by the FAM-C method, the authors found it necessary to include issues related to their diagnosis in this study. In the FAM-C method, the signal from the AC generator during the normal operation of the helicopter is processed. Analysis of this signal allows simultaneous monitoring of multiple engine and transmission components simultaneously. It does not require any separate sensors for this purpose - one "full-time" alternator or tachometer generator is - with proper collection and processing of the output voltage signal - the source of a whole range of diagnostic information. Thus, one generator is an observer of the technical condition of many elements of the power unit simultaneously. What's more, the signal can be collected from any place in the electrical network, which makes it possible to install the measuring system in safe locations, even while the power train is running. Some examples of diagnostic symptoms leading to wear detection are described. Research based on analysis of these findings with the use of the FAM-C method is described in the paper. In the FAM-C method, signal from the AC generator used in routine operation of the helicopter is processed. Signal analysis enables simultaneous monitoring of several engine and transmission elements. Some examples of diagnostic symptoms used to detect wear are described in the paper. [ABSTRACT FROM AUTHOR]

A vibration-based diagnostics method of large-power 1JAH5 (Siemens) DC motors over 660 kW used in paper machines is proposed in the article. When studying vibration spectrograms it was found that 8 Hz frequency shock loads considerably prevail over vibration, which corresponds to this motor rotor speed. The cause of vibration initiation generated by the motor rotor spinning was determined by theoretical methods. Vibration on the one hand appears as a result of bearings wear accompanied by bearing cage deformation and their shaft spinning axes reciprocal displacement, and on the other hand, by shaft eccentricity radii enhancement which causes dynamic loads increase affecting bearing units. The authors of the paper have come to the conclusion that in order to lower vibration of the motor it is necessary to replace the bearings with the new ones, the former due to a long-term service (over 30 years), vibration and shock load effects having exhausted their life span. [ABSTRACT FROM AUTHOR]

This study compares the performance of a plain bearing, with a similar structure to a tail shaft stern bearing, lubricated with either mineral oil or an environmentally acceptable lubricant (EAL). The main characteristic of the bearing is its length/diameter ratio of <1. Measurements are carried out with the bearing operating under loads from 0.5 to 1 MPa and seven speeds ranging from 1 to 11 rev/s. The bearing lubricated with either mineral oil with a viscosity grade of 100 or an environmentally acceptable lubricant (EAL) with a viscosity grade of 100 or 150 is investigated according to the ISO standard. Bearing wear is simulated by increasing the clearance circle by 0.1 mm. According to the results obtained, the use of an EAL in place of mineral oil does not cause significant changes in the bearing performance, regardless of the value of the clearance radius. The pressure distribution in the oil film, bearing load carrying capacity, eccentricity and friction coefficient have similar values for the entire load and speed ranges considered, and the discrepancies in the results are within the range of the measurement errors. Only an increase in EAL viscosity causes significant changes in bearing performance and these changes comply with the general theory of lubrication. [ABSTRACT FROM AUTHOR]

A new bearing is proposed for the input roller system in stands of the 170 section rolling mill at PAO MMK. A model of slip-bearing wear establishes the influence of the bearing parameters, the functional characteristics of the materials, and the surface quality on the bearing life, frictional force, and contour pressure. [ABSTRACT FROM AUTHOR]

Fault identification is a recurrent topic in rotating machines field. The evaluation of fault parameters allows better maintenance of such expensive and, sometimes, large machines. Unbalance is one of the most common faults, and it is inherent to rotors functioning. Wear in journal bearings is another common fault, caused by several start/stop cycles – when at low rotating speed, there is still contact between shaft and bearing wall. Fault parameter identification generally uses deterministic model–based methods. However, these methods do not take into account the uncertainties inherently involved in the identification process. The stochastic approach by the Bayesian inference is, then, used to account the uncertainties of the fault parameters. The generalized polynomial chaos expansion is proposed to evaluate the inference, due to its faster performance regarding the Markov chain Monte Carlo methods. Deterministic and stochastic approaches were compared; all were based on experimental vibration measurements of the shaft inside the journal bearings. The Bayesian inference with the polynomial chaos showed reliable and promising results for identification of unbalance and bearing wear fault parameters. [ABSTRACT FROM AUTHOR]

Aiming at the problems of severe wear of the pitch bearing of wind turbines and large economic losses, a modeling method based on data acquisition and monitoring and control（SCADA） data for wind turbine pitch bearing wear warning was proposed. New feature variables were constructed using sliding window statistics based on the operating parameters of the wind turbine such as pitch motor current, pitch angle, wind speed and power. Then the feature variables and label data were imported into the random forest algorithm for model training and verification. Finally, an early warning model for monitoring the wear of the pitch bearing was established. With the historical data of 20 wind turbines of a wind farm were taken as the input, and the unit fault record was taken as the output mark, a reasonable early warning rule was set and an early warning model was established and verified. The test results show that the pitch bearing wear warning model can issue early warning information 5 days to 30 days in advance, and the accuracy rate can reach 87.9% on average. Through trial operation, it is found that the model has the characteristics of low cost, high efficiency and strong interpretability, which is of great significance for improving the safe operation time of the unit and reducing the operation and maintenance cost of the unit. [ABSTRACT FROM AUTHOR]

Condition monitoring of components in internal combustion engines is an essential tool for increasing engine durability and avoiding critical engine operation. If lubrication at the crankshaft main bearings is insufficient, metal-to-metal contacts become likely and thus wear can occur. Bearing temperature measurements with thermocouples serve as a reliable, fast responding, individual bearing-oriented method that is comparatively simple to apply. In combination with a corresponding reference model, such measurements could serve to monitor the bearing condition. Based on experimental data from an MAN D2676 LF51 heavy-duty diesel engine, the derivation of a data-driven model for the crankshaft main bearing temperatures under steady-state engine operation is discussed. A total of 313 temperature measurements per bearing are available for this task. Readily accessible engine operating data that represent the corresponding engine operating points serve as model inputs. Different machine learning methods are thoroughly tested in terms of their prediction error with the help of a repeated nested cross-validation. The methods include different linear regression approaches (i.e., with and without lasso regularization), gradient boosting regression and support vector regression. As the results show, support vector regression is best suited for the problem. In the final evaluation on unseen test data, this method yields a prediction error of less than 0.4 °C (root mean squared error). Considering the temperature range from approximately 76 °C to 112 °C, the results demonstrate that it is possible to reliably predict the bearing temperatures with the chosen approach. Therefore, the combination of a data-driven bearing temperature model and thermocouple-based temperature measurements forms a powerful tool for monitoring the condition of sliding bearings in internal combustion engines.

Introduction/purpose: The paper presents the application of modern methods in the diagnostics of sliding bearings and the analysis of influencing factors that can cause errors in such an application. Possibilities to determine with certainty when and where problems affect sliding bearings during system operation are presented. It is also shown how the system will continue to function over time. Causes of failures and the manner of their elimination are predicted, as well as the time for planned maintenance of technical systems. Method: The new method solves the problem of sliding bearing diagnostics by measuring the dynamic trajectories of the sleeve in the sliding bearing and by measuring vibration parameters on the inner and outer surfaces of the technical system. The dynamic trajectories of the bearing sleeve are measured with non-contact probes; therefore, the centering of probes in relation to the geometric center of the bearing is very important. Vibration parameters, directly related to the clearance in the sliding bearing, are measured on the inner and outer surfaces of the system. The choice of vibration parameters and measuring points is very important. This method has a number of advantages over other diagnostic methods, as it is easy to access measuring points. Results: By measuring the dynamic trajectory of the sleeves in the plain bearing and vibration parameters on the inner and outer surfaces, the bearing clearance quantities are determined, including: normal condition, initial clearance size, its further increase, bearing clearance sizes, and the moment when the condition parameters are close to the upper limit of the permissible bearing clearance. Conclusion: New diagnostic methods and monitoring systems can be widely applied to: internal combustion engines, all piston machines, hydroelectric power plants, thermal power plants, processing plants, and many other systems. [ABSTRACT FROM AUTHOR]

Wear of the journal bearings in a diesel engine is usually caused by asperity contact. Increased contact potential is caused by the asperity contact between the journal bearing and the shell. This paper analyzes the relationship between the contact potential and asperity contact and presents a method based on contact potential to monitor the bearing wear caused by asperity contact. A thermo-elastic hydrodynamic lubrication (THL) model of the journal bearing on the test bench was established and was verified by measuring its axis orbit. The asperity contact proportion was calculated based on this THL model, and its relationship with the measured contact potential was determined. The main contribution of this paper is to present a new method for monitoring the lubrication conditions of journal bearings in a diesel engine based on contact potential. The results showed that (a) when the minimum oil film thickness was less than 5 μm, asperity contact occurred between the bearing shell and the journal, which led to a sharp increase in contact pressure and a rapid increase in friction power consumption. Further, (b) there was a positive correlation between contact potential and asperity contact. The contact potential was greater than 0.75 mv when asperity contact occurred. These results proved that asperity contact could be accurately monitored using the contact potential, and the feasibility of using the contact potential to monitor the lubrication condition of a bearing was verified. [ABSTRACT FROM AUTHOR]

Introduction/purpose: The purpose of this paper is to present the importance of applying a new diagnostic method with a monitoring system and its capability to reliably determine when and where the problem will occur related to the wear of plain bearings in further operation of the plant, to offer a quality assessment of how the system will continue to function over time, to predict causes of failures and how to eliminate them as well as to provide time for planned maintenance of technical systems. Method:The new method solves the problem of sliding bearing diagnostics by measuring the dynamic trajectories (orbit) of the sleeve in the sliding bearing. Modern methods of technical diagnostics based on the measurement of dynamic parameters and electrical quantities and their analysis enable the support of measuring systems and measurement sensors from different manufacturers. Results: Measurements of the dynamic trajectories of sleeves in sliding bearings determine the values characterizing: normal condition, initial clearance size, further clearance increase, bearing clearance sizes, the moment when the state parameters are close to the upper limit of the allowable clearance, and the specific clearance size when further plant exploitation can cause system failure. Conclusion: The new diagnostic method and monitoring systems can be widely applied in all technical fields: internal combustion engines, hydroelectric power plants, thermal power plants, process plants, and in many other areas. Many monitoring systems, compatibility of devices and equipment of different manufacturers are supported by hardware and software. The calculations of theoretical and experimental dynamic parameters were verified. The method has a wide range of possibilities of application. [ABSTRACT FROM AUTHOR]

Hard turning is a critical machining operation that imposes strict requirements on both the cutting and machine tools. The condition of the machine in terms of its stability and ability to maintain proper operating conditions is very critical in a hard turning operation. Bearing wear and fixture alignment are two critical machine health factors that exert a great influence on the hard turning operation. This paper presents models to support hard turning processes. In particular, models have been developed to predict cutting tool flank wear and forces in hard turning based on experimental data. It has also artificially simulated bearing wear and fixture misalignment failures and developed models that can predict such failures in their incipient or propagating stages. These models were developed using regression as well as neuro-fuzzy techniques. Their performance was evaluated in two situations: distant future state predictions and predictions in the presence of noise. It was observed that neuro-fuzzy models perform better than regression models. [ABSTRACT FROM AUTHOR]

Background: Highly cross-linked polyethylene (HXLPE) liners in total hip arthroplasty (THA) have demonstrated decreased wear rates, resilience to cup orientation, and reduced osteolysis compared to conventional polyethylene. Sequential irradiation and annealing below the melting temperature is unique compared to most HXLPE which is irradiated and remelted. This study purpose is to provide minimum 5-year femoral head penetration rates of sequentially annealed HXLPE in primary THA.Methods: A retrospective review of a prospectively collected database identified 198 consecutive, cementless primary THAs utilizing sequentially annealed HXLPE (X3; Stryker, Mahwah, NJ). Operative technique was standardized. Radiographs were analyzed utilizing the Martell method with minimum 5-year and 1-year radiographs as baseline to minimize the initial bedding-in period.Results: Seventy-seven hips with minimum 5-year follow-up were analyzed. Mean steady state linear and volumetric head penetration rates were 0.095 mm/y and 76 mm3/y, respectively. Volumetric head penetration was significantly less for 32-mm compared to 36-mm (P = .028). In addition, less head penetration was observed for ceramic 32-mm heads at nearly half the rate compared to cobalt-chromium 36-mm heads (P ≥ .092). No correlations existed between penetration rates and age, body mass index, University of California Los Angeles Activity Level, polyethylene thickness, cup inclination, or anteversion (P ≥ .10). No radiographic osteolysis was observed.Conclusion: Surprisingly, linear head penetration rates of sequentially annealed HXLPE were nearly identical to the osteolysis threshold for conventional polyethylene and greater than reports of irradiated and remelted HXLPE. Furthermore, these data corroborate reports that HXLPE is resilient to cup orientation and demographic variables. Longer term follow-up is recommended. [ABSTRACT FROM AUTHOR]

Wear of the journal bearings in a diesel engine is usually caused by asperity contact. Increased contact potential is caused by the asperity contact between the journal bearing and the shell. This paper analyzes the relationship between the contact potential and asperity contact and presents a method based on contact potential to monitor the bearing wear caused by asperity contact. A thermo-elastic hydrodynamic lubrication (THL) model of the journal bearing on the test bench was established and was verified by measuring its axis orbit. The asperity contact proportion was calculated based on this THL model, and its relationship with the measured contact potential was determined. The main contribution of this paper is to present a new method for monitoring the lubrication conditions of journal bearings in a diesel engine based on contact potential. The results showed that (a) when the minimum oil film thickness was less than 5 μm, asperity contact occurred between the bearing shell and the journal, which led to a sharp increase in contact pressure and a rapid increase in friction power consumption. Further, (b) there was a positive correlation between contact potential and asperity contact. The contact potential was greater than 0.75 mv when asperity contact occurred. These results proved that asperity contact could be accurately monitored using the contact potential, and the feasibility of using the contact potential to monitor the lubrication condition of a bearing was verified.

This paper discusses the development of linear vernier hybrid machines for use in wave energy converters. A number of topology options are explored to reduce magnet usage and improve performance for use as a linear generator. Consequent pole, V-shape, and Halbach arrays are designed for a target 25 kW specification. A discussion of overall cost of energy produced is used to justify using efficiency and power factor to asses fixed magnet mass topology variants. A power factor improvement from 0.38 to 0.72 is presented. Physical integration of the electrical machine into wave energy converters is considered including flooded experimental results of thermal behavior and polymer bearing wear. [ABSTRACT FROM AUTHOR]

The contribution describes concrete example of application of tribotechnical methods for the determination of the bearing wear state in aircraft turboshaft engines. Tribotechnical methods, which will be mentioned, deal with qualitative and quantitative characterization of particles occurred in oil. Here belong method optical emission spectrometry method with rotating disc electrode for determination of chemical elements concentration in oil. Method of optical particles counting for detection of particles distribution according to their scale, determination of their number and ferrographic analysis. Exploitation of these methods make it possible to determine quickly and correctly the friction regime and wearing of friction pair that is washed by oil in observed engines. [ABSTRACT FROM AUTHOR]

Dynamics of the helicopter rotor (blade vibrations, ground resonance, influence of forward speed etc.) plays a significant role in wear of transmission and engine systems. Particularly severe wear of these elements can be expected on military helicopters operating in battlefield conditions, where exceedances of dynamic flight parameters and harsh maneuvers occur more frequently. The “FAM-C” diagnostic method, developed by the Air Force Institute of Technology in Poland, has been used for assessing and monitoring a fatigue wear. Particularly, this method may be applied to monitor defects of power plant and helicopter transmission system, where other “classical” methods are less efficient due to the very complex variable system as for the direction and frequency, system of forces generating vibrations in kinematic pairs situated close to each other. Due to this reasons certain vibroacoustic and thermal effects develop around these pairs and they interfere with each other. In a helicopter, a power plant, including a power transmission system is also a carrying assembly. It forced designers to construct a power plant with increased number of joints and bearing supports. This article depicts possibilities of FAM-C method regarding wear of the main bearing of helicopter rotor, wear of surface of teeth contact, clearances between axles of gear wheels in gear and the evaluation of circumferential clearances on splined connections. In the FAM-C method, signal from the AC generator used in routine operation of the helicopter is processed. Signal analysis enables simultaneous monitoring of several engine and transmission elements at the same time. It doesn’t require any separate sensors - one permanent electric generator or tachometer generator is - by the appropriate way of picking up and converting the output voltage signal - a source of the whole gamut of diagnostic information. [ABSTRACT FROM AUTHOR]

The article describes test results of rolling bearings conducted on turbojets, with the simultaneous use of two diagnostics methods: FAM-C and FDM-A [7]. For these methods, no installation of additional sensors on the aircraft is needed - the on-board electric generators are used as sensors. The "FAM-C" method uses the aircraft's alternating current (AC) tachometer generator, whereas the "FDM-A" method uses the direct current (DC) commutator-type generator. Spectrum of angular velocity of individual bearings manifests itself in high frequency ranges (60-240 Hz for the tachometer generator, 3-10 kHz for the DC generator), making the oscillation signal resistant to noise. This frequency modulated signal can be picked up by measuring instruments in any point of the aircraft electrical system. After detection the initial signal is obtained. Measurement analysis can be easily automated [10]. During detection, the carrier frequency is filtered off. Currently, with the simultaneous use of correlated FAM-C and FDM-A methods, four models of rolling bearings wear can be detected: increase of aggregate friction, seizure of rolling elements, increase of radial clearances, increase of axial clearance. This division was made on the basis of observing the technical condition of rolling bearings on many (around 30) turbojets during its normal operation. [ABSTRACT FROM AUTHOR]

In the engineering practice, knowing the technical condition of industrial equipment under operating results shortening of repairs, repairs machinery to smart planning based on the time evolution of bearing wear, detect and correct errors on their installation or repair. This is one of the most important objectives of proactive maintenance; maintenance engineer must follow and monitor the wear of equipment with moving parts to prevent damage and removing them permanently from service, ensuring repair costs as low as possible. The aim of this paper is to present a particular case study on vibro acoustic diagnosis of equipment and components subject to wear during operation to prevent catastrophic damage, as well as human and material losses. [ABSTRACT FROM AUTHOR]

Ways to reduce radial loads on the bearings of electric machines with an electric traction drive are considered. An idea of compensation for radial loads is proposed, and a mathematical model of the electric motor drive with the controlled radial forces in the vertical direction is developed on the basis of a field-regulated reluctance machine. The model takes into account the influence of the vertical forces that are generated by various machine windings and wear in the mechanical part of the electric motor. Additional winding is used to appropriately assess the influence of the radial force. The maximum vertical force acting on the machine is calculated from the obtained waveforms. This fact allowed us to identify the future direction of research. Methods of mathematical modeling construct the dependence of the vertical force from the currents flowing in the windings of the electric machine. The minimum force is created when the field current changes, and the maximum force is created when the armature circuit current is varied. This indicates that the winding provides maximum compensation for the radial force. [ABSTRACT FROM AUTHOR]