pdf [downloaded 1102 times]
wing demands for high reliability of constructions made of composite materials lead to a significant development of non-destructive testing methods of structural diagnostics. Among the most accurate and sensitive techniques used for analysis of internal defects, is the computed tomography (CT). However, since the results obtained from CT are highly precise, certain problems with their interpretation occur. The visual information about defects has isotropiccharacter, thus it is not possible to evaluate directions of propagation of defects. The following study presents an investigation on a problem of identifying the directionality of delaminations evolution in layered composites. The tests were performed on specimens made of polymeric composites with delamination resulted from water-jet cutting. The images of cross sections of specimens were acquired by CT scanning. In the paper, the developed algorithm based on wavelet and Hough transforms as well as other methods of image processing and analysis is presented. The proposed method allows for automatic detection of directionality of delaminations and could be applied in quality control of composite components as well as non-destructive testing during their operation.
pdf [downloaded 1216 times]
The paper deals with the proposal of new maintenance scheme of air brake system on a semi-trailer combination. The structure of semi-trailer and the current maintenance scheme of trailers are described with focus on the basic air brake system design. Analysis of wear and damage of air brake system components used on the semi-trailer combination based on real experience from practice and creation of the FMECA analysis of the system using software support are presented. Based on the analysis performed, a new scheme of maintenance was designed which was aimed at reduction of the risk related to failure consequences. Main objective was to reduce the impact of any failure in any component on the air brake system. Proposed intervals of preventive maintenance execution are based on the calculation of the total costs associated with the consequences of failures that may arise from them and compared with costs associated with service inspections carried out on the analysed semi-trailer fleet.
pdf [downloaded 1050 times]
There has recently been a significant increase in the number of publications on and applications of bioelectric signals for diagnostic purposes. While the use of ECG (electrocardiography) is not surprising, the use of signals from registration of brain activity (EEG) and muscles activity (EMG) still finds new applications in various fields.
The authors focus on the use of EMG signals for estimating hand grip force. Currently, EMG signals are broadly used in limb rehabilitation after severe injuries, surgeries, long immobilizations. Such parameters as maximal voluntary contraction (MVC) used for that purpose do not enable comparison of the forces generated by the muscles, for example, of two different people. It is connected, inter alia, with individual features of the studied person, as well as with a significant scatter of the measured EMG values for the same muscle, e.g. on different days of EMG measurements.
The paper presents results of preliminary research whose final effect is to develop a procedure allowing force estimation in force units and estimation of the accuracy of the results. A series of tests was performed on two people. The tests showed the most important elements influencing disturbance of homogeneity of the obtained measurements with the same stimulation of the muscle. The authors focus only on determining hand grip force.
pdf [downloaded 1027 times]
This paper presents a universal stand to diagnose air gear models made in the process of Rapid Prototyping (RP) at the production stage.
The stand is designed in an open system, powered by a three-phase electric motor with a power of 0.75 kW, whose speed is controlled by a single-phase inverter. The stand is equipped with two measuring shafts, connected directly to a recorder RMC that allow you to read values torque and rpm in real time. Between this measuring shafts installed a gear reducer to allow the exchange of tested pair of gears. Powder brake with variable speed control is installed on the output as a load. Responsible for data acquisition software is copyright RMC-M - Monitor, which allows you to preview the results of measurements and print them in a report.
Trials conducted on the universal test stand for air gears demonstrators give reproducible, stable work parameters and thus enable to obtain uninterrupted, accurate measurements.
pdf [downloaded 1048 times]
This paper presents an application of the ground penetration method (GPR) for diagnostics of reinforced concrete structures. In situ measurements were conducted for three civil engineering structures: the ground floor structure, the abutment of the railway viaduct and the concrete well. The dual polarized ground penetrating radar with the antenna operating at a center frequency of 2 GHz was used for GPR surveys. Three different methodologies of measurements were analyzed. The results showed that the GPR method enables quick and efficient diagnostics of concrete structures. Based on GPR results it is possible to identify the distribution and amount of reinforcement, as well as the thickness of the concrete layer.
pdf [downloaded 1193 times]
The purpose of this research was to determine the conditions for cooperation amongst various components of belt transmission systems in grain harvesters in terms of thermal loads acting on them under operational conditions. A number of field research tests were conducted, using the thermal image measurement method, where selected structural elements of the belt transmission systems were depicted with a thermal imaging technique. The authors focussed on the methodological benefits and problems resulting from the research manner adopted. The authors presented results which could provide a valuable source of information of a utilitarian nature as they could be used for diagnosing the technical condition of kinematic nodes in the mechanical transmission systems in question.
pdf [downloaded 1074 times]
The paper presents results of experimental investigations on damage detection using guided wave propagation technique. The tested specimen was a steel plate with a defect in the form of a rectangular notch. Lamb waves were excited by a PZT actuator and sensed by a laser vibrometer. Since reflections from damage in registered signals are often masked by measurement noise, for identification of time of reflections from damage, continuous wavelet transform (CWT) was used. Obtained results indicated that application of wavelet signal processing enabled precise reconstruction of reflected wavefront from damage.
pdf [downloaded 1343 times]
pdf [downloaded 1426 times]
pdf [downloaded 660 times]
pdf [downloaded 1061 times]