MECHANICS AND CONTROL

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Adres wydawniczy: Kraków : Wydawnictwa AGH, 2010-2016
O czasopiśmie: http://journals.agh.edu.pl/mech
ISSN: 2083-6759 e-ISSN: 2300-7079
DOI: http://dx.doi.org/10.7494/mech
Poprzedni tytuł: Mechanics (2005-2009)

Mechanics and Control wydawane w latach 2010-2016, wcześniej pod tytułem Mechanics ukazywało się w latach 2005-2009.

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Now showing 1 - 20 of 168

Access status: Open Access ,
Modelling of amplitude-selective-damping valves
(2011) Gołdasz, Janusz P.
The so-called amplitude-selective-damping (ASD) valving is a relatively new approach for modifying the output of a hydraulic shock absorber. In the automotive industry ASD valves are known to improve isolation from road inputs. During more aggressive maneuvers the systems maintains the performance of a standard (non-ASD) shock absorber. In the paper, the author derives and analyzes a fairly complete state-space model of an exemplary piston-side ASD valve. The model includes key geometric and performance characteristics of the valve. The results are shown in the form of phase plane plots of force-displacement diagrams, respectively, for a twin-tube shock absorber configuration of choice.
Mechanics and Control
2015 - Vol. 34 - No. 4
Access status: Open Access ,
Investigations of influence of vibration on human-operator control functions
(2010) Basista, Zygmunt; Książek, Marek A; Tarnowski, Janusz
In the paper results of experimental investigations of the system operator-handle-base have been presented. The aim of investigations was to record and analyse dynamical reactions of human operator volunteers participating in the experiments on a visual, suddenly appearing step signal. The main task of each operator was tracking of the signal as precisely as possible with a push force exerted on the tool handle. The measurements were done on an especially designed stand. The stand allows to simulate vibration of the tool with chosen frequencies with or without handle isolation. Time histories of step reference and forces realized by the operator were statistically elaborated and graphically presented.
Access status: Open Access ,
Designing folding wall box pallets
(2014) Wolny, Stanisław; Ładecki, Bogusław; Matachowski, Filip
Designing of modern box pallets with folding walls, which are used for example to transport tires, requires fulfilment of a number of performance requirements. Such pallets, adapted to be moved by forklifts, are stored or transported without loading with walls folded, and during operation they are put together in the piles of a few pieces and braced by the transport belts. Difficult operating conditions are related to necessity to provide resistance of construction of a pallet or their pile on: bending, piling, stability, hitting in case of a free-fall, lifting by forklift, as well as the resistance to horizontal strokes by both edges and legs. In order to meet the above mentioned requirements, it is necessary to implement the relevant tensile FEM analyses, which are then reviewed by the relevant experimental testing. The paper discuss the requirements specified by standards for designing of the above mentioned pallets and presents FEM results in the process of pallets' designing.
Mechanics and Control
2011 - Vol. 30 - No. 2
Access status: Open Access ,
Damage localization and monitoring of load changes in truss structures
(2014) Mendrok, Krzysztof
In recent years one can observe an increasing interest of the researchers, both from academia and industry, in the development of systems for the monitoring of health structures. The main fields of application for these systems are rotating machinery, aircrafts and other means of group transport and civil engineering structures. Many of the latter, contain truss elements in its structure. That is why detection and possible localization of the fault in such a structures is crucial for the safety of its operation. In this paper the application of modal filtration to damage detection and localization in the truss structures is presented. The results of numerical simulation an laboratory experiment are shown.
Mechanics and Control
2010 - Vol. 29 - No. 4
Access status: Open Access ,
Finite element analysis of adhesive bonds using the cohesive zone modeling method
(2014) Korta, Jakub; Młyniec, Andrzej; Zdziebko, Paweł; Uhl, Tadeusz
This paper covers the subject of FE modeling of adhesive joints, which is gaining more and more attention in contemporary industry, especially in the aerospace and automotive sectors. This technique of creating structural connections possesses many advantages over mechanical or welding methods and it seems that it will be exploited extensively in the future mechanical design. The ability of joining dissimilar materials decreased minimum member cross-section size and corrosion inertness can be considered as its most important features. However, in the era of virtual prototyping, it is necessary to conduct reliable computer-assisted analyses of these types of joints. It is because most of the contemporary structures are developed as numerical models first, and only the final pro duct is prototyped physically, to validate the simulation results. The aim of this paper is to demonstrate how to elaborate reliable and accurate adhesive joint models, using a cohesive zone modeling (CZM) method in conjunction with shell-based models. The major profitable consequence of using this modeling technique is that it results in a relatively small number of spatial degrees of freedom, therefore allows for short computational times.
Mechanics and Control
Vol. 35 (2016)
Access status: Open Access ,
Significance of rivet flexibility for load transfer in lap joints
(2010) Skorupa, Małgorzata; Machniewicz, Tomasz; Korbel, Adam; Skorupa, Andrzej
Presented in this paper are results of an experimental investigation on the rivet flexibility and load transmission in a riveted lap joint representative for the aircraft fuselage. The test specimens consisted of two aluminium alloy Alclad sheets joined with three rows of rivets. Rivet flexibility measurements have been performed under constant amplitude fatigue loading using several methods including two novel optical techniques developed by the present authors. The axial forces in the sheets required to determine the rivet flexibility have been derived from strain gauge measurements. In order to eliminate the effect of sheet bending the strain gauges have been bonded at the same locations on the outside and faying surface of the sheet. Variations of the rivet flexibility during the fatigue loading as well as the dependence of the rivet flexibility and load transmission on the rivet squeeze force have been studied. The experiments enabled to evaluate the usefulness of various techniques to determine the rivet flexibility. It was observed that although the measured flexibility was identical for both outer rivet rows, the load transfer through either of these rows was different. Previous experimental results of the authors suggest that the non-symmetrical load transfer distribution through the joint is associated with large differences between the rivet hole expansion in the sheet adjacent to the driven rivet head and the sheet under the manufactured head. It has been concluded that commonly used computation procedures according to which the load transfer is only related to the rivet flexibility may lead to erroneous results.
Access status: Open Access ,
Damping of the waves motion in a span by the active distributed force
(2010) Łatas, Waldemar
In the paper the problem of optimal damping of the waves - traveling along the cable in a span and reflected - by the active distributed damping force segment located near the support is analyzed. The string equation is chosen as a model of the vibrating cable. As an objective function of the optimization problem the energy dissipated by the damper force is assumed. The damping algorithm is based upon the expression for the optimal concentrated damping force. The distributed force is assumed to be proportional to the component of the cable velocity resulting from the superposed motion of the original running and the original reflected waves. The original running waves are assumed in the form of packet waves with amplitude modulation. Illustrative numerical results demonstrating the optimal damping coefficients are included.
Mechanics and Control
2011 - Vol. 30 - No. 4
Access status: Open Access ,
Criterion for angle prediction for the crack in materials with random structure
(2011) Podgórski, Jerzy
Presented paper contains results of fracture analysis of brittle composite materials with a random distribution of grains. The composite structure has been modelled as an isotropic matrix that surrounds circular grains with random diameters and space position. Analyses were preformed for the rectangular 'numerical sample' by finite element method. FE mesh for the examples were generated using the authors' computer program RandomGrain. Fracture analyses were accomplished with the authors' computer program CrackPath3 executing the 'fine mesh window' technique. Calculations were preformed in 2D space assuming the plane stress state. Current efforts focus on brittle materials such as rocks or concrete.
Mechanics and Control
2013 - Vol. 32 - No. 1
Access status: Open Access ,
Power spectral density analysis of vibrations of antennas installed on telecommunication mast
(2011) Orkisz, Paweł
The effect of wind influence on the construction of a telecommunication mast located in an area with average building height not exceeding 10 meters above ground has been presented in this work. The presented telecommunication mast is a lattice construction equipped with four stay lines. Radio, television and cellular phone network antennas are placed on the mast. Analysis of the mast vibrations was carried out using the ANSYS pack.
Access status: Open Access ,
Multichannel data acquisition system for vibroacoustic signals
(2012) Piechowicz, Janusz; Pawlik, Paweł
The authors have made an attempt to construct a multi-channel data acquisition system for vibroacoustic signals, collected for analysis of acoustic field distributions in enclosed rooms and determination of surface acoustic impedance values at the wall surfaces. The scope of the study required a synchronic registration of acoustic pressure by 24 measurement microphones, determination of the phase-shift angles between the measured signals and determination of the vibration velocity for the loudspeaker diaphragm. The paper presents the first stage of the research, directly related to the multi-channel system for registration and analysis of vibroacoustic signals. The constructed research tools, due to their modular structure, can be adapted to new tasks, extended by adding new elements (further measurement cards, microphones, accelerometers etc.), what ensures greatflexibility and suitability of the system for realization of advanced acoustical measurements. Open source code and users request for specialized acoustic analyses make the developed software packages a highly prospective research tool both for today and tomorrow.
Mechanics and Control
2011 - Vol. 30 - No. 1
Access status: Open Access ,
Coupled problems of interaction of deformable bodies and liquid of high pressure
(2013) Šumel'čik, Kseniâ; Kuz'menko, Vasil' Ìvanovič
Nowadays the problems of interaction between solids and liquid under high and extremely high pressure are fairly relevant. So the main aim of presented research work is: creating the mathematical models and methods to investigate the interaction of bodies that include cracks filled with a compressible liquid or gas. The coupled problem of interaction of nonlinear elastic bodies and liquid of high pressure was considered. The pressure exerted by a liquid or gas present in the cavities of solids depends on the deformation of the body. In turn the deformation is caused by the pressure inside the cavity. The interaction between a deformable body and liquid is presented as a variational problem. The iterative splitting process of the coupled problem was proposed as well as the algorithm of numerical solution based on variational approach and finite element method. The software which allows calculating the stress state of an elastic body for some classes of problems was developed basing on the algorithm of splitting. The plane problem with cavity and solid stamp which imposes pressure on the boundary was considered and the numerical solution was computed using created software.
Access status: Open Access ,
Sound absorption coefficients of granular materials
(2010) Sikora, Jan; Turkiewicz, Jadwiga
This paper presents the results of the expanded research program on sound absorbing properties of granular materials (granular polypropylene, foamed polystyrene, gravelite, rubber, mineral wool, and high-silica sand) being often applied as sound absorbing cores in double-wall partitions of constructions limiting noises of machines and devices.
Access status: Open Access ,
Endurance analysis of Koepe pulleys with peripheral ribs
(2012) Wolny, Stanisław; Ładecki, Bogusław
There are numerous hoisting installations operated in Polish mines that are equipped with winding gear incorporating a Koepe pulley reinforced with peripheral ribs, where the symptoms of fatigue cracking are often revealed. Current repairs of those areas help mitigate for this undesirable phenomenon for a short time only. In order to eliminate this problem, steps have been taken to identify the origins and propagation patterns of fatigue cracks in Koepe pulleys. A numerical model of a Koepe pulley is developed and the endurance analysis is performed by the FEM method, preceded by a dynamic analysis of the normal duty cycle of the hoisting installation. The results of dynamic and endurance analyses are verified through experimental testing on a real object, involving force and stress measurements taken at selected points on the Koepe pulley. Those measurement data provide the background for the fatigue endurance assessment and new redesigns of the Koepe pulley structure.