Browsing by Subject "vibrations"

Now showing 1 - 6 of 6

Access status: Open Access ,
Analysis of cutting picks trajectory and cutterhead vibrations of roadheader with use of high-speed cameras
(Wydawnictwa AGH, 2017) Mann, Rajmund; Czerwiński, Kamil; Matusik, Kamil
In order to identify the behavior of cutting picks during the process of mining with the use of a roadheader's cutterhead, an optic system has been employed. The main elements of the system were high-speed cameras. In conjunction with TEMA Motion 3D software (which is designed to analyze movement based on images registered in videos), this allowed for a detailed analysis of the trajectories of the boom, cutterheads, and cutting picks during the process of cutting. This article presents the process of conducting measurements as well as the results of a comparative analysis of the boom vibrations and movement trajectories of cutting picks on the cutterhead for selected cut types: progressive and degressive.
Access status: Open Access ,
Comparison of passive and active methods for sound radiation reduction from the clamped plate
(2010) Kozupa, Michał; Wiciak, Jerzy
The paper is an analytical and experimental study of smart structure, which consist of steel plate with bonded PZTs and porous elastomer layer. Active control of sound radiation from a clamped at the edge square plate is examined. Simulations and numerical computation of the experiment are performed in ANSYS environment. Calculations of plate vibration and sound radiation under stepped harmonic force are performed. The experimental set-up is placed in coupled reverberation chambers and the test plate is placed in the hole. A variety o test cases were studied for three different plates: steel plate + PZT, steel plate + elastomer layer, steel plate + PZT + elastomer layer. The aim of the paper is to illustrate the possibilities of using piezoelectric materials as an active control and elastomer layers as passive methods in one structure to improve the transmission loss.
Access status: Open Access ,
Diagnostics and life prediction of pumping unit reducers by vibration analysis
(2008) Kopej, Bogdan Volodimirovič; Bednarz, Stanisław; Stefanišin, Oksana
The problem of determination of the technical state of pumping units reducing gears sharply is based on the estimation of their resource in the process of exploitation and after the repair in the conditions of repair base. It is especially needed to know descriptions of vibrations of reducing gears of pumping units by which it is possible to judge about the presence of defects, wear, damages or deformations of basic assemblies of reducing gears of different type. On the basis of classification of defects and connection them with vibroacoustic descriptions of reducing gears of pumping units the method of estimation of their technical state is developed and a remaining resource is forecast. During the long term work of machine the change of its state is fixed on the basis of collection and treatment of statistical information about the parameters of vibration. As a diagnostic parameter the dispersion of level of vibration is often used in practice. Acceptable the procedure of comparison of spectrum of vibrosignal, measured on the diagnosed equipment, with the spectrum of vibrosignal, measured before on equipment, or on equipment in good condition. On the basis of the vibroacoustic signal processing it is possible to define quality of repair. The use of functional-cost analysis of reducing gears of pumping units is conducted for cutting of costs on their repair.
Access status: Open Access ,
Experimental investigations on energy harvesting from mechanical vibrations of buildings using Macro Fiber composite
(Wydawnictwa AGH, 2016) Grzybek, Dariusz; Micek, Piotr Andrzej
The monitoring of a structure (e.g., a building) enables safe utilization of such a structure. A large number of sensors that measure selected parameters are often required in applied monitoring systems. Cables or batteries are used to power such sensors. This leads to an increase in utilization costs, as the cables have to be spatially located in a monitored building structure, or batteries have to be changed periodically. The use of the natural properties of piezoelectric materials that convert mechanical energy into electrical energy in places where sensors are mounted is a promising field of wireless monitoring system development. This article presents the results of an experimental study for an energy harvesting system using a piezoelectric composite - the Macro Fiber Composite (MFC). The device used for energy harvesting has a beam structure that was achieved by gluing steel and MFC together. In laboratory research, the characteristics of generated currents and electrical power were obtained for several values of vibration amplitude. The most important conclusion was that the resonant frequency of a piezoelectric beam generator should be established (by the selection of proper dimension or/and mass) both for the vibration frequency of the monitored mechanical structure and the vibration amplitude of this structure.
Access status: Open Access ,
Influence of low frequency vibrations on drillstring dynamics
(2014) Černova, Miroslava Êvgenìïvna
During the drilling process, between the drilling bit that ruins the rock in the bottom-hole and the energy source located on the ground surface is the drillstring that has certain length and small cross cuts that define the dynamics of the drilling bit work. Along with the development of science, for optimization of drilling processes were developed and continue to be elaborated mathematical models that use empirical dependencies based mainly on laboratory data which are very far away from the real conditions of well construction and fail to take into account all the peculiarities of this process. Thus, the management of the drillstring dynamics related to an increase in the effectiveness of deep directional and horizontal wells drilling process through the minimization of torsional and longitudinal low frequency vibrations of drilling instrument is a matter of topical interest nowadays.
Access status: Open Access ,
Skale SWD - zastosowanie wyników analizy Matching Pursuit do oceny oddziaływania drgań na obiekty
(Wydawnictwa AGH, 2010) Sołtys, Anna
The problems of analysis of vibrations induced by blasting works in open cast mines by the application of the various methods temporarily-frequency, giving information about during signal, its frequency structure as well as its energy in this paper. As a wide range of information makes it possible to propose the results of Matching Pursuit (MP) method to assess the impact vibrations on the building constructions.