Szymon Gontarz

A Model-Based Method for Remaining Useful Life Prediction of Machinery

Remaining useful life (RUL) prediction allows for predictive maintenance of machinery, thus reducing costly unscheduled maintenance. Therefore, RUL prediction of machinery appears to be a hot issue attracting more and more attention as well as being of great challenge. This paper proposes a model-based method for predicting RUL of machinery. The method includes two modules, i.e., indicator construction and RUL prediction. In the first module, a new health indicator named weighted minimum quantization error is constructed, which fuses mutual information from multiple features and properly correlates to the degradation processes of machinery. In the second module, model parameters are initialized using the maximum-likelihood estimation algorithm and RUL is predicted using a particle filtering-based algorithm. The proposed method is demonstrated using vibration signals from accelerated degradation tests of rolling element bearings. The prediction result identifies the effectiveness of the proposed method in predicting RUL of machinery.

Impact of Various Factors on Relationships Between Stress and Eigen Magnetic Field in a Steel Specimen

Many materials which could cause a real threat of a catastrophe due to fatigue, exceeding stress limits or plastic strain have magnetic properties that could affect the local magnetic field. Though active magnetic methods of condition monitoring are quite well-known and widely applied however, passive techniques which are based only on the existence of natural magnetic field of the Earth, still require research and improvement. It is obvious that every physical object within the magnetosphere interacts with Earths magnetic field and is subjected to special laws of physics. Such objects can attract or deflect magnetic field lines around their matter. Own magnetic field of an object: H= -grad(w), where w is the magnetic potential, is a function of the gradient of magnetization: w = w(div M). Therefore, the measure of magnetic field of an object depends on an objects magnetization and distribution of its volume in the medium (space). Considering magnetoelastic effects (Villari Effect, magnetostriction), the additional stress causes transformation of the material to magnetic state which reflects the magnetization of an object. The magnetization depends on many factors. Magneto-mechanic phenomena have been known for a long time but as the technology developed, there have emerged new possibilities of acquisition, processing and analysis of these phenomena and of their use in technical diagnosis. Following a simple model analysis, a laboratory experiment was proposed and performed. By controlling plastic and elastic range of the specimens strain, we have investigated the existence of a relation between stress and degree of magnetization, which is strictly connected with deformation and effort. Magnetic anomalies which are generated due to magneto-mechanic effect were collected by the three axial fluxgate magnetometer, which allowed presentation of own magnetic field component, which was least sensitive to the disturbance present in a real world. Experiment included in the paper confirms the existence of a relationship between stress and magnetization degree which additionally depends on the kind of material. In addition the possibility of remote identification of magnetoelastic effects has been contemplated and examined. Finally the paper analyzes the impact of the shape of specimen on the interaction between Earth and eigen magnetic fields during a tension test. Further directions and comments on development of techniques which allow exact stress assessment of technical objects made of ferromagnetic materials have been included.

Research Study of the Micro Cogeneration System with Automatic Loading Unit

This article presents the test bench research of a micro cogeneration system with the Stirling engine with an automatic loading system. The tests were conducted for nitrogen as a working gas. The work presents the influence of the load current on the change of the working gas pressure in the working chamber and on the changing voltage on the electric machine. A significant number of repetitions allowed for a statistical rendering of the research description with the use of such measures as: kurtosis, coefficient of variation, coefficient of asymmetry, and of the function of the probability density. The research allows for determining whether the conducted experiment is reproducible and how the chosen parameters influence the character of the system’s work.

Distributed System for Monitoring of the Large Scale Infrastructure Structures Based on Analysis of Changes of its Static and Dynamic Properties

The complexity and diversity of civil engineering structures impose requirements on the monitoring systems, which are difficult to be satisfied. In the paper the concept of the distributed diagnostic system capable of monitoring the technical state of critical elements of large infrastructure objects like steel trusses, supermarket buildings, exposition halls, bridges etc. is discussed. Adaptation of such systems is essential for online assessment of technical state of the infrastructure objects and could limit the possibility of catastrophic disasters with loss of people. As a source of information data from strain gauges, passive magnetic field sensors and acceleration sensors applied to the construction are considered. For the process of selection of sensors and diagnostic methods the mathematical model of the construction and the physical test stand were used.

Research on a Micro Cogeneration System with an Automatic Load-Applying Entity

The article concerns the testbed research of a micro cogeneration system based on a Stirling engine equipped with an automatic load-applying system. The article presents the influence that the load current has on acceleration of vibration of a micro cogeneration system’s body. The research was conducted while using nitrogen as the working gas. Significant number of tests offered the possibility of providing the description of the results in statistical terms while using such measures as kurtosis, coefficient of variation, the asymmetry coefficient as well as the probability density function. The research offers the possibility of concluding whether the completed experiment is repeatable as well as for determining the impact that selected load changes have on acceleration of the micro cogeneration system’s vibration.

Online Monitoring of Steel Constructions Using Passive Methods

In the chapter the possibilities of development of distributed diagnostic system capable of online structural health monitoring of civil engineering structures are discussed. Instead of commonly used methods of determining the technical state of the construction that are usually focused on searching for cracks, material heterogeneities and assessing concrete or steel degradation, the methods proposed for the system are based on the comparative strain gauge, acceleration and passive magnetic measurements. All this measurement methods are used for stress assessment in critical fragments that are vital for stability and durability of the structure. Evolution of defects in the construction causes measurable changes of stress distribution in critical joints of the construction. Additionally, materials that could cause threat of the catastrophic accident caused by fatigue wear, exceeding stress limits or emerging of plastic deformations have magnetic properties that could affect the local magnetic field. Stress limits could be then constantly supervised taking into account the range of permanent and elastic deformation, which would allow for early detection of threats. SHM data analysis is taking into consideration a series of magneto-mechanical and other phenomena occurring during the construction/machine’s operation and also actual magnetization conditions of the object examined in exterior magnetic field (Earth’s or derived from adjacent elements).

Diagnosis of Supporting Structures of HV Lines Using Magneto-Mechanical Effects

This paper concerns the idea of using magneto-mechanical effects in prophylactic activities to reduce the risk of occurrence of an extensive blackout on high voltage (HV) lines. The subject matter of the paper is related to the event from April 8, 2008, which deprived approximately 600,000 recipients from 18 cities of the West Pomeranian voivodeship of power and caused millions in losses for the national economy. In theoretical considerations, the idea of diagnosing the technical state and level of effort of steel power line towers using the metal magnetic memory method (MMM) is presented, with a consideration of the methodology for obtaining a reference signal from the external magnetic field. The capabilities of the MMM method have been illustrated by examples of active and passive experiments. Finally, the authors indicated the need of IT support of MMM data analysis using a 3D model of the predicted distribution of the magnetic field in the vicinity of the tested object.

Diagnostic Model of Hysteresis for Condition Monitoring of Large Construction Structures

The conception of diagnostics, based on passive magnetic field measurements is being presented. It was shown that the transformation of the signal to the appropriate form of hysteresis, creates new potential for identifying changes in signal parameters that correspond to specific physical phenomena. Model supported analysis of changes in the magnetic field, made it possible to obtain diagnostic parameters characterizing magnetomechanical hysteresis, which can be used in determining the state of the material strain on the object structure subjected to variable loads. Suitable model of hysteresis was elaborated and conditions in which it could be applied were stated. Obtained by authors diagnostic parameter confirm the validity of the hysteresis model used for this case. The chapter concludes that state of polarization of the magnetic structure (the distribution of magnetization) is carrier of diagnostic information about the level of effort and the progressive degradation of the material structure. It is possible to obtain the diagnostic information through a remote, non-contact measurement of magnetic field near the test structure.

Shape of specimen impact on interaction between earth and eigenmagnetic fields during the tension test

Many materials that could cause real threat of the catastrophe caused by fatigue wear, exceeding stress limits or emerging of plastic deformation have magnetic properties that could affect the local magnetic field. As far as quite well known and applicable are active magnetic methods for condition monitoring, passive techniques which bases only on the existence of natural magnetic field of Earth still need researches and improvement. It is obvious that every physical object, which enclose in magnetosphere interacts for Earth magnetic field, follows to special physics lows. Such objects could focus or deflect the magnetic lines around its matter. Own magnetic field of object: H = -∇(w) where ‘w’-magnetic potential, is a function of magnetization gradient: w = w (div M). So, the measure magnetic field of object depends on object magnetization and distribution of this volume in medium (space). Considering magnetoelastic effects (Villary Effect, magnetostriction), the additional stress causes transformation to magnetic state of material which reflect to magnetization of object. This magnetization depends from many factors. In this paper shape of specimen impact on interaction between earth and eigenmagnetic fields during the tension test is considered. Due to simply model analysis, the laboratory experiment was proposed and performed. Controlling plastic and elastic range of specimen deformation, there was proved that exist relation between stress and magnetization degree which is strict connected with the deformation and effort state. Magnetic anomalies which are generated due to magneto-mechanic effect were collected by the three axial fluxgate magnetometer what allows exhibition of the own magnetic field component, which is least sensitive for the disturbances which are present in the real world. In the paper, it was proved that exist dependence between the stress and magnetization degree but it is very complex because additionally it depends on magnetization, history of magnetization, deformation and the shape of object. Also, the place of measurement relative to the shape of object has the influence on results. Further directions and comments about development of the techniques for technical state objects evaluation which could make use with the presented effects, were included.

Use of passive magnetic method for stress assessment

Many materials that could cause real threat of the catastrophe caused by fatigue wear, exceeding stress limits or emerging of plastic deformation have magnetic properties that could affect the local magnetic field. As far as quite well known and applicable are active magnetic method for condition monitoring, passive techniques which bases only on the existence of natural magnetic field of Earth still need researches and improvement. It is obvious that every physical object which enclose in magnetosphere interacts for Earth magnetic field, follows to special physics lows. Such objects could focus or deflect the magnetic lines around its matter. Own magnetic field of object: H = −▿(w) where ‘w’-magnetic potential, is a function of magnetization gradient: w = w (div M). So, the measure magnetic field of object depends on object magnetization and distribution of this volume in medium (space). Considering magnetoelastic effects (Villary Effect, magnetostriction), the additional stress causes transformation to magnetic state of material which reflect to magnetization of object. Due to simply model analysis, the laboratory experiment was proposed and performed. Controlling plastic and elastic range of specimen deformation, there was proved that exist relation between stress and magnetization degree which is strict connected with the deformation and effort state. Magnetic anomalies which are generated due to magneto-mechanic effect were collected by the three axial fluxgate magnetometer what allows exhibition of the own magnetic field component, which is least sensitive for the disturbances which are present in the real world. In the paper, it was proved that exist dependence between the stress and magnetization degree but it is very complex because additionally it depends on the kind of material and magnetization, history of magnetization and on deformation and temperature. Calculation for model evaluation was performed. This leads to general dependence which allow for reliable stress estimation: M=M(stress, plastic strain, shape and dimension of object, measurement distance). Further directions and comments about development of the techniques which allows exact stress assessment of technical objects made with ferromagnetic materials, were included.