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1
Content available Analiza mostów wiszących w opracowaniach Stephena Timoshenki
100%
Dąbrowiecki K.
Nowoczesne Budownictwo Inżynieryjne
|
2022
|
tom Nr 2
86--88
PL
29 maja 2022 r. minie 50 lat od śmierci Stephena Timoshenki, amerykańskiego naukowca ukraińskiego pochodzenia, autora znanych prac z teorii sprężystości, teorii stateczności sprężystej, wytrzymałości materiałów oraz mechaniki budowli. Tym artykułem chcę przypomnieć czytelnikom mniej znany wkład tego wybitnego uczonego w teorię mostów wiszących.
2
Content available remote Friction forces for human hip joint lubrication at a naturally permeable cartilage
88%
Wierzcholski K. C.
International Journal of Applied Mechanics and Engineering
|
2006
|
tom Vol. 11, no 3
515-527
EN
This paper presents the various kinds of friction forces occurring in human joint gap. Author indicates some main factors which can change the friction forces in human joint. Friction forces for squeezing, boosted squeezing and weeping in macro, micro and nano level for porous cartilage are presented here. According to the author's knowledge the problem of human joint lubrication in unsteady motion has not been hitherto considered in the scientific papers on bio-tribology.
3
Modelowanie dynamiki układów napędowych maszyn roboczych metodą grafów sieciowych
88%
Nowak A. , Czapla K. , Kaczmarek K.
Maszyny Dźwigowo-Transportowe
|
2002
|
tom nr 3
12-19
PL
W pracy sformułowano zagadnienie modelowania modeli dynamicznych układów napędowych maszyn transportowych z zastosowaniem grafów sieciowych w reprezentacji macierzowej. Model dynamiczny sieci przepływowej określono wprowadzając zmienne biegunowe w wierzchołkach sieci oraz zmienne przepływowe przyporządkowane gałęziom sieci. Model matematyczny przepływów sieciowych określono wprowadzając pojęcie globalnej macierzy przepustowości układu, w szczególności dla układów hydraulicznych. W pracy przedstawiono izomorficzne układy fizyczne dla danej sieci potencjalnej. Opracowano metodę hybrydowych grafów wiązań do modelowania złożonych układów dynamicznych umożliwiającą badanie wrażliwości układu ze względu na parametry projektowe. W pracy zamieszczono wyniki analizy przepływów sieciowych na przykładzie dynamicznego układu wibroizolacji z napędem hydraulicznym.
EN
In the paper the problem of the analysis of the modelling of the dynamical models of the driving systems by use of the networs graphs in the matrix representation has been formulated. In the paper the isomorphoused with the driving system the potencial networks graphs are shown. There the hybrid bond graphs method is elaborated to modelling of the complex dynamical systems and the sensitivity model of the system regard to the parameters. The results of the analysis of the flows on example of the dynamical model of the hydraulical driving system with vibroisolation element are shown.
4
Content available Stephen Timoshenko - ojciec mechaniki stosowanej (okres emigracyjny). cz. 2
75%
Dąbrowiecki K.
Nowoczesne Budownictwo Inżynieryjne
|
2010
|
tom Nr 4
70-72
PL
W numerze 1 (22) "Nowoczesnego Budownictwa Inżynieryjnego" z 2009 r. ukazała się pierwsza część materiału poświęconego prof. Stephenowi Timoshence (Stiepanowi Prokofiewiczowi Timoszence) 1878.1972, światowej sławy specjaliście w dziedzinie mechaniki stosowanej Artykuł ten opisywał działalność profesora w okresie przedemigracyjnym. Jednak najwięcej szeroko znanych prac naukowych napisał i opublikował, będąc na emigracji w Stanach Zjednoczonych i właśnie tego okresu jego życia i działalności dotyczy poniższy artykuł.
5
Content available remote Modified strip saturation model for a cracked piezoelectric strip
75%
Bhargava R. , Setia A.
Archives of Materials Science and Engineering
|
2008
|
tom Vol. 30, nr 1
33-36
EN
Purpose: The investigations aim to propose a model for arresting an electrical opening of a crack which weakens a narrow, poled and infinite piezoelectric strip. The edges of the strip are subjected to uniform, constant anti-plane stresses and in-plane electrical displacements. Design/methodology/approach: The loads applied at the edges of the strip open the crack in a self-similar fashion. Consequently at each tip of the crack a saturation zone protrudes. To stop the crack from further opening the rims of developed saturation zones are subjected to normal, cohesive linearly varying saturation limit electric displacement. The edges of the strip are subjected to anti-plane deformation and in-plane electrical displacement. Fourier integral transform method employed reduces the problem to the solution of a Fredholm integral equation of second kind. Findings: The electrical displacement, stress intensity factor, the saturation zone length, crack opening displacement and crack growth rate have been calculated. The results obtained presented graphically, analysed and concluded. Research limitations/implications: The ceramic used for strip is being assumed to be electrically more brittle. The investigations are carried at this level in the present paper. Also the small scale electrical yielding is considered. Consequently the developed saturation zone is proposed to lie in a line segment ahead of crack. Practical implications: Piezoelectric ceramics being widely used as transducers. Their wide utility has prompted to study many attires of such ceramic and one such attire is fracture mechanics of these ceramics. Originality/value: The paper gives an assessment of the electrical load necessary to arrest the electrical crack opening. The investigations are useful to smart material design technology where sensors and actuators are manufactured.
6
Content available remote Characteristics of discrete-continuous flexibly vibrating mechatronic system
75%
Buchacz A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2008
|
tom Vol. 28, nr 1
43-46
EN
Purpose: The purpose of this paper is application of approximate method of solving the task of assignment the frequency-modal analysis and characteristics of flexibly vibrating mechatronic system. Design/methodology/approach: The main approach of the subject was to formulate and solve the problem in the form of set of differential equation of motion and state equation of considered mechatronic model of object. Galerkin's solving method has been used. The considered flexibly vibrating mechanical system is a continuous beam, clamped at one of its end. Integral part of mechatronic system is a transducer, extorted by harmonic voltage excitation, to be perfectly bonded to the beam surface. Findings: The parameters of the transducer have important influence on values of natural frequencies and on form of characteristics of the discussed mechatronic system. Research limitations/implications: In the paper the linear mechanical subsystem and linear electric subsystem of mechatronic system has been considered, however for this kind of systems the approach is sufficient. Practical implications: The methods of analysis and obtained results can be base on design and investigation for this type of mechatronic systems. Originality/value: The mechatronic system formed from mechanical and electric subsystems with electromechanical bondage has been considered. This approach is different from those considered so far.
7
Content available remote New branched vibrating systems as result of synthesis of selected class of characteristics
75%
Buchacz A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2007
|
tom Vol. 23, nr 1
15-22
EN
Purpose: of this paper is the application of the synthesis method according to realization of mobility or immobility function into partial fraction when the level of the denominator of characteristic is higher than the level of its numerator. Design/methodology/approach: was formulated and formalized by the problem of obtaining the "new" discrete vibrating mechanical systems with branched structures. The models of mechanical systems were represented by polar graphs. The reverse problem of dynamics of defined class of vibrating mechanical systems was also formalized and solved. Findings: this study is that the same class of polar graph is a model of mechanical system with "old" and "new" branched structure. Obtaining structures of graphs as models of mechanical systems are a physical realization of dynamical characteristics, which may be considered as the immobility or mobility function. Research limitations/implications: is that the linear vibrating discrete mechanical systems with branched structures were considered. Practical implications: of this researches was that another approach was presented, which that means unclassical method of modeling of different structures of mechanical systems in form of polar graphs was used. The used method of synthesis and the obtained results can be of some value for designers of designated class of vibrating mechanical systems. Originality/value: of this paper is that the only one polar graph is obtained as a model of not only one mechanical system. The results are obtained after distribution of two dynamical characteristics into partial fraction of finding structures of mechanical systems. This approach is other than those considered elsewhere.
8
Content available remote Ocena skutków zderzenia statku ze skałą
75%
Puch W. , Sperski M.
Problemy Eksploatacji
|
2001
|
tom nr 2
193-201
PL
Przedstawiono sposób wyznaczania sił wewnętrznych w kadłubie statku, wywołanych zderzeniem kadłuba ze skałą. Opis zjawiska zderzenia oraz ocenę jego skutków oparto na analitycznym i numerycznym całkowaniu równań ruchu kadłuba modelowanego liniowo-sprężystą, cienkościenną belką. Posługując się modelem materiału sprężysto-plastycznego oraz metodą elementów skończonych, określono także wielkości obciążeń powodujących trwałe odkształcenia dna ładowni.
EN
Stress determination in the ship's hull during the collision with a rock is presented. The description of the crash phenomena and the results assessment is based on the numerical and analytical integration of the moving equations of the hull modelled with the linear-elastic thin-walled beam. Using the elasto-plastic material model and the finite element method, the loading caused permanent deflection of the cargo hold inner bottom plating has been calculated.
9
Content available Analytical solution of the time fractional Fokker-Planck equation
75%
Sutradhar T. , Datta B. K. , Bera R. K.
International Journal of Applied Mechanics and Engineering
|
2014
|
tom Vol. 19, no. 2
435--440
EN
A nonperturbative approximate analytic solution is derived for the time fractional Fokker-Planck (F-P) equation by using Adomian’s Decomposition Method (ADM). The solution is expressed in terms of Mittag-Leffler function. The present method performs extremely well in terms of accuracy, efficiency and simplicity.
10
Content available remote Exact and approximate analysis of mechanical and mechatronic systems
75%
Buchacz A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
|
tom Vol. 33, nr 1
47-52
EN
Purpose: of this paper is to compare the transients of characteristics obtained by the approximate method and exact one and to answer to the question – if the method can be used to nominate the characteristics of mechatronic systems. Design/methodology/approach: was to nominate the relevance or irrelevance between the characteristics obtained by considered methods – especially concerning the relevance of the pole values of characteristics. The main subject of the research is the continuous torsionally vibrating bar considered as a mechanical subsystem of the mechatronic system. Findings: this approach is fact, that approximate solutions fulfill all conditions for vibrating bars and some conditions only, particularly for flexibly vibrating beams. Research limitations/implications: is that linear continuous torsionally vibrating bar is considered. Practical implications: of this study is the main point is the analysis and the examination of torsionaly vibrating continuous mechatronic systems which characteristics can be nominated with similar methods only. Originality/value: of this approach relies on the comparison of the compatibility of the characteristics of the mechatronic and mechanical systems with demanded accuracy, nominated with similar method.
11
Content available remote Life and operational safety of power systems and chemical plants
75%
Okrajni J.
Journal of Achievements in Materials and Manufacturing Engineering
|
2010
|
tom Vol. 43, nr 1
38-63
EN
Purpose: The problem addressed in the paper is the description of an effort and durability of components under the conditions of mechanical and thermal interactions. The problems of proper material testing methods have been shown as the important part of the components life assessment methodology. Design/methodology/approach: The FEM modelling has been used to determine the stress and strain fields in the components and to describe their behaviour under mechanical and thermal loading. Findings: An appropriate models description has been developed. So far, experimental verification of the usefulness of the model description to determine the stress and strain patterns in particular object and for chosen operation conditions has been made. Research limitations/implications: The developed description should be useful in problems of behaviour predictions of high temperature components and their durability assessment under different mechanical and thermal loadings in industry practical applications. Originality/value: The method, which more precise description of power industry components behaviour makes possible have been shown in the work. The work is addressed to researchers interested in problems of component behaviour prediction under different loadings that we can meet in the operation practice and to power industry engineering maintenance staff.
12
Content available remote Stephen Timoshenko - ojciec mechaniki stosowanej (okres przedemigracyjny). cz. 1
75%
Dąbrowiecki K.
Nowoczesne Budownictwo Inżynieryjne
|
2009
|
tom Nr 1
86-88
PL
Życiorys "ojca mechaniki stosowanej" Stephena Timoshenki. W artykule przedstawione zostały jego losy do roku 1922, kiedy to opuścił na stałe Europę i wyemigrował do Ameryki.
13
Content available remote Dynamical flexibility of torsionally vibrating mechatronic system
75%
Buchacz A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2008
|
tom Vol. 26, nr 1
33-40
EN
Purpose: of this paper is the application of the approximate method called Galerkin's method to solve the task of assigning the frequency-modal analysis and characteristics of a mechatronic system. Design/methodology/approach: was the formulated and solved as a problem in the form of a set of differential equations of the considered mechatronic model of an object. To obtain the solution, Galerkin's method was used. The discussed torsionally vibrating mechatronic system consists of mechanical system, which is a continuous bar of circular cross-section, clamped on its ends. The electrical subsystem of the considered mechatronic system is a ring transducer to be perfectly bonded to the bar surface. Findings: this study is that the parameters of the transducer have an important influence on the values of natural frequencies and on the form of the characteristics of the said mechatronic system. The results of the calculations were not only presented in a mathematical form but also as transients of the examined dynamical characteristic which are a function of frequency of the assumed excitation. Research limitations/implications: is that the linear mechatronic system was considered, for this type of systems, such approach is sufficient. Practical implications: of this researches was that another approach is presented, that means in the domain of frequency spectrum analysis. The method used and the obtained results can be of some value for designers of mechatronic systems. Originality/value: of this paper is that the mechatronic system, created from mechanical and electrical subsystems with electromechanical bondage was examined. This approach is other than those considered elsewhere.
14
Content available remote Steam pipelines' effort and durability
75%
Okrajni J. , Mutwil K. , Cieśla M.
Journal of Achievements in Materials and Manufacturing Engineering
|
2007
|
tom Vol. 22, nr 2
63-66
EN
Purpose: The main problem addressed in the paper is the description of an effort and durability of steam pipelines under the conditions of mechanical and thermal interactions. Design/methodology/approach: The FEM modelling has been used to determine the stress and strain fields in the pipelines and to describe their behaviour under mechanical and thermal loading. Findings: An appropriate model description has been developed. So far, experimental verification of the usefulness of the model description to determine the stress and strain patterns in particular object and for chosen operation conditions has been made. The analysis made has shown that the most probable cause of cracks occurence on the analyzed chosen pipeline' inner surfaces are thermal deformations and constraints of their dislocations. Research limitations/implications: The developed description should be useful in problems of behaviour predictions of high temperature components and their durability assessment under different mechanical and thermal loadings in industry practical applications. Originality/value: The method, which more precise description of power industry components behaviour makes possible have been shown in the work. The work is addressed to researchers interested in problems of component behaviour prediction under different loadings that we can meet in the operation practice and to power industry engineering maintenance staff.
15
Content available remote Thermally induced vibration of an axially-traveling strip: spectral element analysis
63%
Lee U. , Kwon K.
Journal of Achievements in Materials and Manufacturing Engineering
|
2006
|
tom Vol. 17, nr 1-2
261--264
EN
Purpose: A spectral element model is developed for accurate prediction of the dynamic characteristics of an axially-traveling strip subjected to a sudden thermal loading. Design/methodology/approach: The spectral element model is formulated from the frequency-dependent dynamic shape functions which satisfy the governing equations in the frequency-domain and its extremely high accuracy is evaluated by comparing with the conventional finite element model in which simple polynomials are used as the shape functions. Also some numerical studies are conducted to investigate the vibration characteristics of an example axially-traveling strip subjected to a sudden thermal loading on its upper surface. Findings: The present spectral element model is shown to provide very accurate dynamic characteristics by treating a whole uniform strip between two boundary supports as a single finite element, regardless of its length, when compared with the conventional finite element model. Practical implications: Numerical studies for the typical example problem show that the dynamic characteristics of an axially-traveling strip may depend on the traveling speed and the duration and frequency characteristics of the externally applied thermal loading. Originality/value: The spectral element model presented in this paper is the first one for the axially-traveling strips subjected to thermal loadings and is applicable to the engineering problems such as the galvanized steel strip passing through a hot zinc tank, for instance.
16
Content available remote Crack arrest saturation model under combined electrical and mechanical loadings
63%
Bhargava R. R. , Setia A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
|
tom Vol. 37, nr 2
544-548
EN
Purpose: The investigation aims at proposing a model for cracked piezoelectric strip which is capable to arrest the crack. Design/methodology/approach: Under the combined effect of electrical and mechanical loadings applied at the edges of the strip, the developed saturation zone is produced at each tip of the crack. To arrest further opening of the crack, the rims of the developed saturation zones are subjected to in-plane cohesive, normal uniform constant saturation point electrical displacement. The problem is solved using Fourier integral transform method which reduces the problem to the solution of Fredholm integral equation of the second kind. This integral equation in turn is solved numerically. Findings: The expressions are derived for different intensity factors and energy release rate. A qualitative analysis of the parameters affecting the arrest of opening of the crack and fatigue crack growth with respect to strip thickness and material constants are presented graphically. Research limitations/implications: The investigations are carried out by considering the material electrical brittle. Consequently, the zones protrude along the straight lines ahead of the crack tips. And further, the small scale electrical yielding conditions are used. Practical implications: Piezoelectric materials are widely getting used nowadays, even in day to day life like piezoelectric cigarette lighter, children toys etc. And, its advance used in technology like transducers, actuators has been already in progress. So, the aspect of cracking of piezoelectric materials are of great practical importance. Originality/value: The piezoelectric material under the combined effect of electrical and mechanical loadings gives the assessment of electrical displacement which is required to arrest the crack. The various useful interpretations are also drawn from the graphs.
17
Content available remote Analysis of probability as an impulse to synthesis of a beam-system represented by hypergraphs
63%
Buchacz A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2010
|
tom Vol. 38, nr 1
72-79
EN
Purpose: of this paper is to analyze vibrating beam by an exact and approximate methods and to create hypergraphs of the beam in case of two methods of analysis. Design/methodology/approach: was to nominate the relevance or irrelevance between the characteristics obtained by the considered methods - especially concerning the relevance of the natural frequency-poles of beam characteristics. The main subject of the research is a continuous free beam as a subsystem of vibrating beam-system with constant cross sections. Findings: this approach is that approximate solutions fulfil all conditions for vibrating beams and can be an introduction to synthesis of these systems modelled by hypergraphs. Research limitations/implications: linear continuous flexibly vibrating free beam is considered Practical implications: of this study is mainly the introduction to synthesis of flexibly vibrating continuous beam-systems. Originality/value: of this approach is about application of approximate methods of analysis of a beam and modelling the one of transformed hypergraph.
18
Content available remote Computer models of steam pipeline components in the evaluation of their local strength
63%
Okrajni J. , Essler W.
Journal of Achievements in Materials and Manufacturing Engineering
|
2010
|
tom Vol. 39, nr 1
71-78
EN
Purpose: The paper discusses the issue of modelling the heating and cooling processes of T-pipes in a power plant pipeline in the start-up conditions of a boiler. The main purpose of this work is the description of the mechanical behaviour of power plant components working under mechanical and thermal loading and validation of the computer modelling methods. Design/methodology/approach: The FEM modelling has been used to describe the local stress-strain behaviour of the chosen component. Findings: The reasons for the presence of high and variable in time temperature gradients in the components of the main steam pipeline include, among other things, variable values of the coefficient of heat transfer between the pipeline material and the medium flowing inside it, which, at this stage of boiler operation, may change its state. Unsteady operation of a pipeline, especially in case of subsequent boiler start-ups, may induce thermal stresses which exceed the values of allowable stress in components of complex shapes. Research limitations/implications: The possibility of applying the durability criteria currently assumed in standards still requires justification and confirmation in laboratory and industrial conditions to be closer to the real components behaviour. In such situation the presented analysis is the part of the complex investigation method which main purpose is increasing accuracy of the TMF process description and thermo-mechanical life assessment. Practical implications: The calculations carried out may constitute a basis for developing a material test parameters which would bring closer the fatigue conditions appearing locally in the analysed components. The method of stress-strain behaviour analysis used in the paper could be useful in the practical cases when the real components mechanical behaviour would be analysed. Originality/value: The main value of this paper is the own method of the mechanical behaviour analysis of the power plant component. This method includes the temperature fields analysis taking into account the boundary conditions based on the operation parameter data and the thermoplastic material model. The material stress-strain behaviour has been treated as the local phenomenon, that could be modelled by FEM.
19
Content available remote Parameter identification of a full-car model for active suspension design
63%
Guida D. , Nilvetti F. , Pappalardo C. M.
Journal of Achievements in Materials and Manufacturing Engineering
|
2010
|
tom Vol. 40, nr 2
138-148
EN
Purpose: A method for identifying parameters of a full-car model for active suspension design Design/methodology/approach: The method is based on ERA/OKID identification procedure developed by Juang [1]. Findings: Numerical results show a good agreement with real system parameters. Research limitations/implications: Results show that this method works well only with a high signal-to-noise ratio. Practical implications: This method can be used as an aid to active suspension design. Originality/value: This procedure has been tested on the full-car model of suspension system in two cases: a) full-state measurements; b) not full-state measurements.
20
Content available remote Dry friction of bearings on dynamics and control of an inverted pendulum
63%
Guida D. , Nilvetti F. , Pappalardo C. M.
Journal of Achievements in Materials and Manufacturing Engineering
|
2010
|
tom Vol. 38, nr 1
80-94
EN
Purpose: Investigation of dry friction parameters on the control system of a cart pendulum. Design/methodology/approach: A geometrical approach has been used to analyze the influence of bearing friction on the cart-pendulum dynamics. This approach was developed by one of authors in the paper “ Influence of the Variation between Static and Kinetic Friction on Stick-Slip Instability” pubblished by WEAR 1993. Findings: Relations that allow us to evaluate how the friction parameters of bearings influence the performances of the control system of a cart-pendulum. Research limitations/implications: The “a priori knowing” of friction parameters is the intrinsic limitation of this method. Originality/value: A novel methodology for designing of more effective control systems.
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