- TITLE:
PERFORMANCE ANALYSIS OF CONTINUOUS LINEAR MOTION OF SINGLE AND SERIES CONNECTED PIEZOELECTRIC ELEMENTS BY USING METHOD OF IMPACT DRIVE MECHANISM
- AUTHOR(S):
Kuscu H., Kaya U.
- ABSTRACT:
IDM can be defined as the transformation of small vibrations of a piezo element into continuous linear motion on a frictional surface by controlling the extension and contraction speed thus the impact force. In most of previous studies, longitudinal vibrations of piezo elements are employed as in [1], [2], [3] to obtain a continuous linear motion. In this study, linear continuous motion characteristics of series connected piezoelectric (PZT) crystals are investigated both numerically and experimentally, when the method of the impact drive mechanism applied was driven by coupled transverse and torsional vibrations. For the experiments, PZT rectangular crystal bars are series connected with a neodymium magnet glued to the bottom end, and then positioned to a grinded smooth steel surface. The three test specimens were series connected one, two, and three-elements PZT-5X military grade single crystals, and the neodymium magnets were N38 grade coated with nickel. Before starting the tests, resonant frequencies of test specimens are calculated numerically by making harmonic analysis employing a finite element software (ANSYS) and tested experimentally by using the sweep characteristics of the signal generator. Triangular, and sine signal waves at resonance frequencies are applied for each test specimen at 220 Volts. Both the numerical and experimental results showed that the top-end deflection, strain energy, the impact force thus the linear velocity increases by increasing the number of PZT crystal elements of a test specimen. The research conducted here could be supportive when designing nano/micro-scale positioning actuators and driving systems for different kinds of high technology applications.
- DOI:
https://doi.org/10.62853/NJJN9041
- PAGES:
70-76
- HOW TO CITE THIS ARTICLE:
Kuscu H., Kaya U. Perfomance analysis of continuous linear motion of single and series connected piezoelectric elements by using method of impact drive mechanism. Journal of the Technical University of Gabrovo. 67 (2023) 70-76.
- TITLE:
THE INFLUENCE OF THE PROCESS OF FRICTION - ABRASION ON THE AIR PERMEABILITY AND APPEARANCE OF CLASSIC COTTON-TYPE SOCKS
- AUTHOR(S):
N. Cirkovic, S. Kapusi, T. Sarac, D. Trajkovic, N. Stamenkovic, J. Stepanovic, A. Ilic.
- ABSTRACT:
Socks are included in the group of everyday (indispensable) items of clothing. They should absolutely be comfortable, long-lasting and affordable. In this research were analyzed three types of socks that differ in raw material composition (mixture of Co, PA and Lycra fibers) and structure (loop density). All socks are made of knitwear in right-left interlacing. The basic characteristics of knitwear from feet, heels and toes were checked: longitudinal mass of yarn, density, loop length, surface mass, thickness. The samples were then subjected to measurements of air permeability and resistance to friction (abrasion) using methods according to ISO and EN ISO standards. After the friction process, the air permeability decreased thanks to the felting, i.e. rubbing the fibers in the structure of the knitwear, making it denser (regardless of the fact that protruding fibers fall out, they create piles of them). The visual assessment of appearance in the sock sections also changed with increasing number of friction cycles.
- DOI:
https://doi.org/10.62853/FSCJ5813
- PAGES:
65-69
- HOW TO CITE THIS ARTICLE:
Cirkovic N., S. Kapusi, T. Sarac, D. Trajkovic, N. Stamenkovic, J. Stepanovic, A. Ilic. The influence of the process of friction - abrasion on the air permeability and appearance of classic cotton-type socks. Journal of the Technical University of Gabrovo. 67 (2023) 65-69.
- TITLE:
DETECTION OF NON-RADIOCONTRAST FRAGMENTS IN MILITARY FIELD SURGERY BY THE NOISE EMITION METHOD
- AUTHOR(S):
O. Salenko, V. Orel, B. Salenko, K. Karpenko, V. Cherniak
- ABSTRACT:
A special tool for inspecting wound canals has been developed, consisting of a flexible probe for individual use and a handle-holder with a microphone capsule, the membrane of which is directly connected to the probe and reacts to mechanical contact with an obstacle, and the capsule itself is directly connected to the oscilloscope through a signal amplifier, which has spectral signal processing chains. Functional conditioning of the controlled signals from the shape and type of the foreign object in the wound channel was revealed. The expediency of using the frequency-amplitude characteristic of noise emission as a controlled parameter has been proven. Thus, the existence of a functional conditioning of the width of the spectrum of the noise emission signal at the time of mechanical contact with a foreign object in the wound, its shape and type is shown; it was determined that the use of an oscilloscope with a spectral analysis channel allows fairly accurate identification of a nonradiocontrast foreign object in a wound.
- DOI:
https://doi.org/10.62853/KUIY9198
- PAGES:
62-64
- HOW TO CITE THIS ARTICLE:
Salenko O., V. Orel, B. Salenko, K. Karpenko, V. Cherniak. Detection of non-radiocontrast fragments in military field surgery by the noise emition method. Journal of the Technical University of Gabrovo. 67(2023) 62-64.
- TITLE:
PARAMETER SCREENING IN LONGITUDINAL TURNING OF C45E STEEL FOR SURFACE ROUGHNESS ANALYSIS
- AUTHOR(S):
M. Trifunovic, M. Madic, P. Jankovic, M. Radovanovic
- ABSTRACT:
Parameter screening refers to the identification of the most important controllable factors with respect to a given performance characteristic of a given system/process. In this study, PlackettBurman design was applied in order to identify the factors that significantly affect surface roughness in longitudinal turning of C45E steel. The experiment involved realization of geometric PlackettBurman design with eight trials and two replicates. Six turning controllable factors were considered in the design matrix (depth of cut, feed rate, cutting speed, insert nose radius, minor cutting edge angle and cooling/lubrication condition) and were varied at two levels. Analysis of the obtained results has shown that factors differently affect surface roughness and that their influences are in accordance with known theoretical knowledge. It was also observed that three factors have statistically significant impact on the machining quality, i.e., arithmetic surface roughness. These results can be considered as the first step for further experimental investigation of significant factors and their possible interactions effects.
- DOI:
https://doi.org/10.62853/FVOS5135
- PAGES:
57-61
- HOW TO CITE THIS ARTICLE:
Trifunovic M., M. Madic, P. Jankovic, M. Radovanovic. Parameter screening in longitudinal turning of C45E steel for surface roughness analysis. Journal of the Technical University of Gabrovo. 67 (2023) 57-61.
- TITLE:
ELIMINATION OF THE DEFECTIVE LAYER AND STRESS CONCENTRATORS DURING MICROMACHINING OF HOLES IN THIN SHEET BLANKS OF METAL CELLULAR PANELS
- AUTHOR(S):
O. Salenko, V. Cholodny, W. Alnusirat, H. Habuzyan
- ABSTRACT:
Thin-sheet blanks made of aluminum (in particular, AMg2-N), titanium (VT-15, VT-19) or stainless (12X17) alloys are widely used in the production of honeycomb panels in the aviation and space industries. Foil (thickness 0.025-0.055 mm) is used for the production of fillers for cellular sandwich panels; it is pre-perforated with holes of 0.05-0.18 mm and laid out in a corrugated box with adhesive strips. The possibility of making holes by the laser jet method is considered, as it precedes the occurrence of mechanical damage and thermal defects of the surface adjacent to the treatment zone. It is shown that the Water Jet Guided Laser (WJGL) is an effective and efficient method of obtaining profile holes in the fillers of cellular panels and in the panels themselves, which is characterized by high productivity and allows obtaining holes without thermal and mechanical defects. The method can be used both for foil fillers and for metal panels made of stainless steel up to 1.5 mm thick.
- DOI:
https://doi.org/10.62853/NSUK6396
- PAGES:
54-56
- HOW TO CITE THIS ARTICLE:
Salenko O., V. Cholodny, W. Alnusirat, H. Habuzyan. Elimination of the defective layer and stress concentrators during micromachining of holes in thin sheet blanks of metal cellular panels. Journal of the Technical University of Gabrovo. 67 (2023) 54-56.
