Solid State Phenomena Vol. 199

Abstract: Over the years various techniques have been developed to extract information on the dynamic state of the rotating machinery. This paper introduces a new method based on the phase data of the shaft rotation angle. Usually the phase data is omitted and only the frequency components of the vibration spectrum are taken into consideration. However, the transverse shaft crack has a specific angular location about the shaft axis. Therefore, it is supposed that by measuring the vibration response of the rotor deflected by an additional constant force applied perpendicularly to the shaft axis at different angular locations, different vibration signatures can be obtained. Such signatures can then be used to detect the crack. The method utilizes also the coupling phenomenon between the lateral/torsional vibrations of the cracked rotor, since the shaft is additionally excited by an external harmonic torque. The computer simulation study is based on the uncracked and cracked rotor models obtained by using the finite element (FE) approach. The results of the numerical analysis demonstrate the potential of the suggested method for the effective shaft crack detection.

Abstract: The paper presents some problems of carrying out measurements of energetic characteristics and vessels performance in the conditions of sea examinations. We present the influence of external conditions in the change of vessels hull resistance and propeller characteristics as well as the influence of weather conditions in the results of examinations and characteristics of gas turbine engine. We also discuss the manner of reducing the results of measurements to the standard conditions. We present the way of preparing propulsion characteristics and the analysis of examination uncertainty for the measurement of torque.

Abstract: The essence of the paper was to design technical condition monitoring and failure diagnostic evaluation method of low rotation speed rotors with self-aligning antifriction roller bearings. The technical condition of bearings and failures of the cylindrical rollers and cylindrical wheels surfaces were tested in situ using mechanical vibration parameters measurement method. The theoretical part of the paper was constrained to the modeling of two cylinders in the case of different damages levels of the spherical roller bearings.

Abstract: A method for estimating external forces acting on a rotating machine system with an additional active magnetic support is described. The verification of the method was carried out on the test stand. The force exerted with an impedance hammer and the effect of its action was compared to the estimated results of the magnetic reaction forces determined with the module of the diagnostic software. Obtained results of the investigations have confirmed the usefulness of the proposed method, which leads to finding the right diagnostic balance between the symptom and the cause and securing a rotating system from damage.

Abstract: Rolling-element bearings have been used in the engineering practice since the very beginning of the XIX century. The scientific literature on the subject is therefore rich. As rotational speeds of bearing shafts were getting higher, new problems appeared. Quite a new challenge to be faced were turbine engines with very high rotational speeds that considerably augmented both the scope of problems and the demand for fast and reliable diagnostic methods. The FDM-A diagnostic method (FM frequency modulation, D direct current, C - the level of the methods advancement) has been based on measurements of frequency modulation of the component of pulsation whereas the FAM-C method (FM frequency modulation, C alternating current, C - the level of the methods advancement, i.e. applications in the form of an automatic tester are in use) has been based on measurements of the alternating-current frequency. Both the methods have been developed at ITWL (Air Force Institute of Technology), Warsaw, Poland. Accuracy of these methods essentially results from the natural synchronization of the sampling signal with the angular velocity of kinematic links under examination. The methods enable abrasive wear of a given subassembly to be determined and localised in the course of the power plants regular operation. Possible is determination of numerous parameters of the bearings themselves, the bearing nodes, and the rotating (compressor-turbine) assembly, just to mention the degree of the rolling friction for any of the bearings, the smoothness of motion of the bearing cage, sizes of radial clearances, the level of abrasive wear of contact surfaces of both the bearing cage and the rolling element. A diagnostic unit is fitted to any item, e.g. an electrical joint, supplied with DC or AC voltage. What has been presented in the paper is findings from the performance testing of the aircraft turbine engine: the role of the generator observer has been played by a DC generator and a three-phase tachogenerator.

Abstract: The paper presents various types of compressor and turbine scoops damages that are being found in the operating process of air turbine engines. When dividing them, having in mind a genesis of their origin, a special attention has been paid to corrosion and high-temperature erosion, often being a reason for destruction of the entire unit.

Abstract: The paper presents the research relevant to knowledge acquisition for marine diesel engine diagnosis. Basic sources of knowledge which can be used for construction of diagnostics knowledge base are identified. The basic knowledge related to the diesel diagnostic was undertaken from experts and from diagnostic database. The paper questionnaire was used to the knowledge acquisition from experts [. With the paper questionnaire the basic knowledge related to the marine diesel exploitation was undertaken. The rule induction algorithms was used to knowledge acquisition from diagnostic database [. Training and test data were acquired from experiment on marine engine Sulzer 3AL 25/30. The paper proposes the original system of knowledge management for the marine diesel engine diagnosis. The system allows the collection of knowledge from different sources, its evaluation and update.

Abstract: Most children with plano-valgus have flexible arches. There is a lot of controversy regarding the results of treatment with foot orthosis, corrective exercises, etc. We hypothesized that data mining and action rule discovery help to understand the relationships among the treatment factors and measurements in order to better understand plano-valgus treatment and gain new knowledge for predicting treatment success. Sixty eligible plano-valgus children and 50 age-matched control children were recruited for this study. The authors developed a flexible temporal feature retrieval system based on grouping the patients of similar visiting frequencies with connection to an action-rules engine, which consists of four modules: a data grouping device, a temporal feature extraction engine, a decision tree classification device, and an action rules generation device.

Abstract: The article describes the structure and the principles of operation of the test system for the investigation of safety of height rescue equipment used by rescue services. The system is composed of a portable computer, data acquisition block and measurement modules equipped with own power supply sources and radio transmission modules. Some of the modules constitute original, mechatronic measurement devices with specific metrological properties. The system is intended particularly for accreditation tests for height rescue equipment used by Fire Brigades.

Abstract: One of the important factors that affect the reliable operation of the power system and the rapid restitution after disaster is a quick and effective combining synchronous electric power facilities to operate in parallel [. Hence, diagnostics of automatic synchronizers at every stage of their life, from building a prototype, through the whole life, until removing such devices from the operation, is an extremely important and responsible activity. In ordinary practice, this action is performed by dedicated test of mechatronics systems, called simulators [2, , in close to real - or even more restricted - conditions. One of the major limitations in the relevant field undoubtedly concerns the selection of an appropriate structure and implementation of models of the angular velocity control systems involved in the process of connection. These models must be simple enough to allow computation with a frequency of kHz, and, at the same time, developed enough to be able to form diverse and close to real working conditions. For these reasons, classical approach is not possible, allowing the use of well-known Parks model [ of the synchronous generator and the complex - and often nonlinear [. Hence, considered above-mentioned requirements and indicated constraints, to test the automatic synchronizer the designers of mechatronics systems use a number of simplifications during modeling of the angular speed control systems [. However, models are not detailed enough to study the impact of changes in the shape of relevant characteristics under the influence of changes the angle of phase discrepancy in the process of connecting. Hence, this paper presents the results of the research of the currently used method of modeling the most commonly used control systems of angular velocity, in the respective systems.