The paper presents the assessment results of probability of detection for damages in mechanical structures conducted with a Structural Health Monitoring (SHM) system based on the measurements of electromechanical impedance. The research was carried out with both numerical models and real-life mechanical components. The results of laboratory tests performed in operational conditions for a bolted pipeline connection confirmed usefulness of both the applied monitoring method and the SHM system. The hit/miss and signal response statistical approaches were employed to gain insight into the specific SHM system reliability.
Bonds between surfaces and coatings are widely used in the construction of machines and
vehicles. Therefore, it is important to prepare a non-destructive method that will allow monitoring
of the process of production of elements containing such bonds. The paper contains a description
of the testing procedure, materials and devices used for the realization of the experiment. As a
result of the experiment, changes in the longitudinal wave reflection coefficient for three areas of
bonding were determined, each of which had the surface prepared in a different way. It has been
found that the ultrasonic method utilizing a longitudinal wave allows monitoring of the process of
constitution of the bond between the putty coating and the body surface and enables to determine
the curing time of adhesive connection and allows detecting defective adhesive bonds and
eliminating them in the stage of production.
Keywords: ultrasound, condition monitoring, coating, adhesion
The article discusses the relationship between the heat flow and the power supplied to a test object. Often, it is reasonable to say that the heat flow and power are correlated. Intuitively, one can assume that knowing the distribution of the heat flow in time permits to determine the power of a system. Such a statement is valid in some cases. In order to determine fault assumptions an experiment was carried out. The object of research was chosen so as to simplify the physical model of the experiment. The goal of the experiment was to study the heating power of systems consisting of tubes filled with water. The signal was recorded using thermistors and a thermal imaging camera. The analysis of the results shows that there is a strong relationship between the power supplied and temperature increase. Information on energy dissipation of a system is characterized by medium and small average error, thus, allows the evaluation of a machine’s performance.
The paper presents one of the methods of digital processing of diagnostic signals such as
cepstral analysis and the possibility of its application in the investigations of sources of wave
disturbances. In order to solve the problem, simulation and diagnostic research was performed.
The simulation experiment consisted in generating different sample signals (by special software)
containing known frequency-related information, which aimed at exploring the information
generated and presented in the cepstrum characteristics and its reliability. The diagnostic
experiment was carried out on an mechanical device – a Ford Transit minivan. The object was a
basis for the determination of the possibilities of practical application of the cepstrum
Damping of mechanical vibrations is often realized by viscous dampers with nonlinear
characteristic. The progressive wear them leads to a deterioration of working conditions of
machinery and vehicles. Bad technical condition of the damper also adversely affects the
occupants of the means of transport. In many cases, there are no effective methods for determining
their condition. The aim of the study was to develop a computational model of the viscous damper
takes account of the characteristics such as nonlinearity and asymmetry and its dependence on the
parameters of extortion. Taking into account the impact of these factors on the instantaneous value
of the force generated by the element enables the use of computational model to determine the
The paper presents numerical and experimental analyses of elastic waves propagation in a bolted lap joint. In experimental investigations condition assessment of the joint was performed with the use of symmetric waves excited by a piezoactuator. Numerical calculations were conducted in commercial finite element method software Abaqus. The influence of number of bolts and the value of the initial stress on recorded signals was examined. The study showed the possibility of using elastic waves in the context of diagnostics of bolted joints.
This paper describes a mobile system for the noninvasive diagnosis of the core of conveyor belts with steel cords. The system is based on the 4-channel magnetic head of the EyeQ system which one of the Polish opencast mines bought at the beginning of the 21st century. Because of the restructuring of the mine and the aging of the EyeQ system, measures were taken to improve the latter’s resolution and performance. The upgrading consisted mainly in developing a new software for data analysis automation and in replacing the old hardware platform with a new one increasing six-fold system resulution. The system has successfully passed tests in mine conditions and is currently used to assess the condition of belts working in the mine transport system (fig. 1)
W artykule przeanalizowano eksperymentalnie wpływ częstotliwości wymuszenia na wyniki pomiarów metodą wibrotermografii. Wibrotermografia jest metodą badań nieniszczących która bazuje na pomiarze zmian temperatury pod wpływem wymuszenia drganiowego w celu wykrycia uszkodzeń w badanym materiale. W niniejszej pracy analizie poddano warstwową płytę kompozytową zbrojoną włóknem węglowym w której zasymulowano uszkodzenie w postaci delaminacji. Uszkodzenie zasymulowano przez umieszczenie w płycie wkładki z politetrafluoroetylenu (PTFE). Płytę poddano wymuszeniu drganiowemu w pewnym zakresie częstotliwości i zaobserwowano iż pewne częstotliwości generują znacznie wyższą odpowiedź
termiczną w uszkodzonym obszarze płyty niż inne i są przez to preferowane w badaniach wibrotermograficznych. Artykuł zawiera szczegółowy opis metody pomiarowej oraz przeprowadzonych badań eksperymentalnych.
Krzysztof SZCZUROWSKI, Stanisław RADKOWSKI, Damian WALCZAK, Łukasz ZIELIŃSKI
With the development of internal combustion engines, engineers attempt to reduce the noise and vibration generated. Due to the high cost of fuel, are increasingly looking for new sources of power in order to reduce costs. In diesel engines, an increasingly popular method is the admixture of propane-butane. This follows because of the price of the fuel as well as to improve the efficiency of combustion. With the development of this type of dual fuel power seems to be a reasonable study of the effects of LPG to generate noise and vibration, as well as an attempt to evaluate the combustion process. The article describes preliminary studies on these phenomena example Yanmar L70 with a modified injection system of diesel and LPG in the gaseous phase. Thepaper presents theresults ofnoise and vibration of dual fule engine using different shares of LPG and camelina oil esters.
An unbalance is the most common issue affecting the turbomachinery rotors. A machine operation at high vibration level due to the rotor disk unbalance will result in the damage to rotor bearings. The vibration level in industrial turbomachinery is hardly ever monitored in online systems to record all exceeded parameters. It is usually monitored in the key process machines. The operation of a supervision system will result in their deactivation at reaching the alarm threshold vibration level. The rotor disk is in almost all cases balanced in its own bearings supporting the shaft using the influence coefficient method. In some cases, the rotor disk is balanced in normal operation using automatic balancers. Although they do not solve the rotor unbalance issue, they reduce the vibration level at any given time. The main disadvantage of the system is its high price, often exceeding the costs of a new pump or fan. If technical conditions allow to stop the rotor for a short period, the disk can be balanced using manual balancers, with a significantly lower cost compared to the automatic balancing equipment. The operation of the manual balancing system is described herein.
Deterioration of lubricate oil in combustion engines enforces measurements of parameters essential for proper operation of define driving system or to certain engine malfunctions indicate. Since the fluorescence phenomenon is known for oil excited by ultraviolet light – the question arises whether fluorescence spectra evolving with the time of exploitation of oil in the engine. In this paper the introductory studies of excitation-emission spectra (EEMs) for chosen lubricate oil are described. Both fresh and used oil (after 593 h of work in a ship engine), was used to measure EEMs. As a result of comparison of EEMs for both fresh and used lubricate oils more significant transformations in fluorescence spectra of oil caused by their exploitation are indicated. Obtained results allow to predict that spectrofluorimetry method could supplement present methods of used lubricating oil testing.