Browsing by Subject "modal analysis"

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Access status: Open Access ,
Metoda oceny jakości wklejenia żerdzi kotwiowych w górotworze jako skuteczny sposób kontroli stanu bezpieczeństwa pracy w wyrobiskach korytarzowych
(2007) Staniek, Andrzej
A rock bolt which is grouted underground may not be properly inserted with the result of discontinuity of resin layer. Such discontinuity may also occur in working conditions due to typical rock behavior and displacement. It may be very hazardous to mine safety. In this paper a method for non-destructive identification of discontinuity of a resin layer surrounding rock bolt is presented. The method used modal analysis procedures and is based on an impact excitation where a response transducer is positioned at a visible part of a rock bolt. As an installed rock bolt acts as an oscillator, different length of discontinuity of resin layer changes its modal parameters. By proper extraction of these parameters, from which a resonant frequency is seen as most valuable, the intended identification is possible. Also the results of research work concerning influence of explosions on installed rock bolts are presented. The investigated rock bolts were localized in a coal mine roadway near the region of explosions of dynamite charge. The test were performed before and after the explosions. The usage of the method was tested in copper mines as well.
Access status: Open Access ,
Numeryczno-doświadczalna analiza drgań wysięgnicy koparki wieloczerpakowej kołowej
(2007) Czmochowski, Jerzy
The adverse vibrations of elements of excavator supporting structure are the significant problem observed during the exploitation of multibucket wheel excavators. The source of these vibrations is the changeable loading from the mining process and from the moving output on the conveyors, as well as the strokes in the tranship points. Because of the large dimensions of these machines significant deflections of masts, fixed jibs, bucket wheel booms and counterweight boom are observed during the machine moving. The aim of the study is the numerical-experimental vibration analysis of the fixed jib of one of the excavators, which the lateral deflections during the mining and moving are observed in. For this reason the equivalent measurement system that bases on the accelerometer sensors for vibration recording and frequency analysis is used. For the numerical simulation, the shell model for calculation with use of Finite Element Method (FEM) that enables to conduct the analyses of local and global vibrations was elaborated. The FEM model was tuned to parameters determined during the measurements done on the object. Correctly prepared computer model has enabled the collaboration of various variants of structural changes, that purpose is to decrease the disadvantageous vibrations of the measured assembly.
Access status: Open Access ,
System monitoringu stanu zabezpieczenia wyrobiska w aspekcie oceny jakości wklejenia żerdzi kotwiowych oraz kotwi linowych
(Wydawnictwa AGH, 2009) Staniek, Andrzej
The rock bolt support system plays a great role as an element of safe maintenance of roof sections in coal mines almost all over the world. With the aim to develop an efficient monitoring system of quality of grouted rock bolts an apparatus of new generation was invented. The monitoring system is based on the method for non-destructive identification of continuity of resin layer of grouted rock bolts [10], worked out in Central Mining Institute. The apparatus has implemented new registration methods, wireless data transfer and robust enclosure capable to resist heavy environmental conditions (IP65). A new way of exporting collected data is proposed as well as launching of analytical and diagnose center for assessment of quality of rock bolt installation in Central Mining Institute is recommended. In the article the outline of the method, technical description of the invented apparatus, wireless data export to a workstation after measurements and validation of the measurement chain are also presented.