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Wyznaczanie dużych ugięć płaskich struktur tekstylnych z wykorzystaniem energii potencjalnej układu

Szablewski Piotr

Przegląd Włókienniczy - Włókno, Odzież, Skóra

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2024

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nr 1

28--33

PL

Głównym tematem artykułu jest wykorzystanie metody energetycznej do rozwiązywania równań różniczkowych ciężkiej elastyki. Metoda ta może być z powodzeniem zastosowana do modelowania dużych ugięć, takich obiektów jak np. płaski pas tkaniny lub liniowy wyrób włókienniczy. Analiza problemu opiera się na zasadzie minimalizacji energii potencjalnej układu. Występujące w pracy zależności na energię potencjalną i energię zginania zostały podane w postaci ogólnej. Do minimalizacji energii potencjalnej wykorzystano rachunek wariacyjny. Wyniki uzyskane podczas analizy można wykorzystać np. do symulacji swobodnego układania tekstyliów płaskich, jak również zginania struktur liniowych.

EN

The main topic of the article is the use of the energy method to solve differential equations describing heavy elastica. This method can be successfully used to model large deflections such objects as a flat strip of fabric or a linear textile product. The analysis of the problem is based on the principle of minimizing the potential energy of the system. The relationships for potential energy and bending energy occurring in this work are given in general form. The calculus of variations was used to minimize the potential energy. The results obtained during the analysis can be used, for example, to simulate the free folding of flat textiles as well as the bending of linear textile structures.

2

Investigation to the influence of additional magnets positions on four-magnet bi-stable piezoelectric energy harvester

Li Xinxin, Huang Kexue, Li Zhilin, Xiang Jiangshu, Huang Zhenfeng, Mao Hanling, Cao Yadong

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 1

art. no. e140151

EN

To enhance the harvesting performance of a bi-stable piezoelectric energy harvester (BEH), this work proposes a four-magnet BEH (FBEH). FBEH consists of a piezoelectric cantilever beam with a tip magnet, a fixed magnet and two movable magnets. The two movable magnets relative to the fixed magnet can move in both horizontal and vertical directions. A nonlinear distributed parameter model of FBEH is derived through the Hamilton principle. The effects of the excitation frequency and amplitude as well as the horizontal and vertical gap on the harvesting performance are mainly investigated by using the bifurcation diagram, phase diagram, Poincaré map and output power. Numerical simulations demonstrate that the proposed FBEH decreases the potential barrier and creates a higher than typical bi-stable one when subjected to lower excitation amplitudes and frequencies.

3

Investigation of internal efforts in the components of the crop sprayer boom section

Hevko R., Stashkiv M., Lyashuk О., Vovk Y., Oleksyuk V., Tson O., Bortnyk I.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 105, nr 1

33--41

EN

Purpose: Development results allow the defects in the boom section of a crop spraying machine design to be found, the most loaded structural components to be determined and the most suitable design parameters to be chosen. Design/methodology/approach: Results of theoretical investigation of internal forces distribution in the components of a boom section of a crop spraying machine in the static statement of the problem have been presented. The applied under discussion enables the static indeterminacy to be realized whilst calculating the complex frame structures though it requires not only considerable records of the function of potential energy of deformation (even without taking into account the function of potential energy of deformation of normal and lateral forces) but application of applied computer programs. The technique of static indeterminacy realization by minimum of potential energy of deformation (MPED) method has been used to calculate the framework. Findings: Technique of static indeterminacy realization by minimum of potential energy of deformation (MPED) method has been used to calculate the framework. The results of theoretical calculation and simulation of the boom section of a crop spraying machine have been compared. The results of analytical calculation have been checked by the simulation of 3D model of the using the program complex «Lira-SAPR», where the finite elements method (FEM) has been implemented. Research limitations/implications: Horizontal components of the shear forces as well as the normal forces and as a consequence the corresponding potential deformation energy are neglected, which has some effect on the accuracy of the calculations. Practical implications: An effective tool for strength analysis with preliminary assessment and diagnostics structures based on the constructed calculation models of stress strain state load-bearing frames of typical geometry with an arbitrarily given distribution of external load. Originality/value: A universal algorithm records of the function of torque and bending moment, as well as the function of potential deformation energy of a spraying machine boom section.

4

Evaluation of strength of carrying metal structures of trailers

Popovych P., Poberezhny L., Shevchuk O., Murovanyi I., Dovbush T., Koval Yu., Hrytsuliak H.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 100, nr 2

58--69

EN

Purpose: Development of a computational model of stress-strain state bearing elements of trailer frames for preliminary assessment and identification of areas with increased risk of failure. Design/methodology/approach: The object of the study is the processes of loading the load-bearing metal structures of trailers - fertilizer spreaders. The stress-strain state of the spreader bearing system is investigated for the established three typical cases of external load. To refine the values obtained as a result of modelling, they were determined in SOLIDWORKS. Findings: Computational models of load have been compiled by improving the method of minimum potential deformation energy for its effective correct use in analytical studies of a similar type of metal structures. It is proved that for a flat closed frame structure made of thin-walled profiles, loaded with forces perpendicular to the plane of the frame, the levelling of compression and shear energies, as well as axial and transverse forces and bending moments in the horizontal plane does not significantly affect the calculation results. Research limitations/implications: Horizontal components of the shear forces as well as the normal forces and as a consequence the corresponding potential deformation energy are neglected, which has some effect on the accuracy of the calculations. Practical implications: An effective tool for strength analysis with preliminary assessment and diagnostics of load-bearing metal structures based on the constructed calculation models of stress strain state load-bearing frames of typical geometry with an arbitrarily given distribution of external load. Originality/value: A universal algorithm for recording additive functions of bending and torques, as well as the potential deformation energy of welded frames of trailers.

5

Effect of different sized multi walled carbon nanotubes on the barrier potential and trap concentration of malachite green dye based organic device

Sen Sudipta, Manik N. B.

Advances in Materials Science

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2020

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Vol. 20, nr 4(66)

16--26

EN

Present work shows effect of 8 nm diameter and 30 nm diameter multi walled carbon nanotubes (MWCNT) on the barrier potential and trap concentration of Malachite Green (MG) dye based organic device. MWCNTs are basically a bundle of concentric single-walled carbon nanotubes with different diameters. In this work, ITO coated glass substrate and aluminium have been used as front electrode and back electrode respectively and the spin coating method is used to prepare the MG dye based organic device. It has been observed that both barrier potential and trap concentration are in correlation. Estimation of both these parameters has been done from current-voltage characteristics of the device to estimate the trap energy and the barrier potential of the device. Device turn-on voltage or the transition voltage is also calculated by using current-voltage characteristics. In presence of 8 nm diameter MWCNT, the transition voltage is reduced from 3.9 V to 2.37 V, the barrier potential is lowered to 0.97 eV from 1.12 eV and the trap energy is lowered to 0.028 eV from 0.046 eV whereas incorporation of 30 nm diameter MWCNT shows reduction of transition voltage from 3.9 V to 2.71 V and a reduction of barrier potential and trap concentration from 1.12 eV to 1.03 eV and from 0.046 eV to 0.035 eV respectively. Presence of both 8 nm diameter and 30 nm diameter MWCNT lowers trap energy approximately to 39% and 24% respectively and lowers barrier potential approximately to 13% and 8% respectively. Estimation of barrier potential is also done by Norde method which shows lowering of the value from 0.88 eV to 0.79 eV and from 0.88 eV to 0.84 eV in presence of both 8 nm and 30 nm diameter multi walled carbon nanotubes respectively. Calculation of barrier potential from both the I-V characteristics and Norde method are in unison with each other. Indication of enhancement of charge flow in the device can be ascribed to the truncated values of barrier potential and trap energy.

6

Moment krytyczny stalowych belek dwuteowych o zbieżnym przekroju

Kuś J.

Inżynieria i Budownictwo

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2017

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R. 73, nr 9

468--470

PL

Zaproponowano sposób wyznaczania momentu krytycznego zwichrzenia bisymetrycznej stalowej belki o zbieżnym przekroju poprzecznym na długości. Do wyznaczenia obciążenia krytycznego zastosowano metodę Ritza. Obliczenia wykonano przy różnych parametrach zbieżności pasów i środnika belki obciążonej momentami skupionymi na końcach. Wyniki zaprezentowano w formie graficznej.

EN

A procedure for critical buckling moment of a bisymmetrical tapered beam is proposed. To compute critical buckling loads Ritz method was used. In particular, critical buckling moments of beams under positive gradient moments with different taper parameters for flanges and the web are considered. Detailed, numerical, parametric analyses are carried out in graphical form.

7

Comparative characterization study of the variability of wind energy potential by wind direction sectors for three coastal sites in Lomé, Accra and Cotonou

Ajavon A. S. A., Salami A. A., Kodjo M. K., Bédja K.-S.

Journal of Power Technologies

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2015

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Vol. 95, nr 2

134--142

EN

This paper presents the characterization of the distribution of wind speeds across sectors of directions in order to study the variability of wind energy potential on sites in Lomé (Togo), Accra (Ghana) and Cotonou (Benin) in the Gulf of Guinea. To this end, we developed a software application in MATLAB aimed at wind data processing. Each site’s wind speed data collected over a period from January 2000 to December 2012 at a height of 10 m above the ground were divided into eight sectors of direction of 45 degrees each, according to the wind directions measured. Parameters such as K (shape factor) and C (scale factor) of Weibull distributions as well as the skewness and kurtosis coefficients were obtained for each sector. The study analyzes the variations of the statistical parameters computed based on the number of hours during which wind blows in each sector of direction. The results show that the South and South-West sectors are areas of prevailing winds and have higher wind energy potential compared to other sectors in general on the 3 sites considered. The more frequent the wind blows in a sector of direction, the higher the Weibull parameters, while the coefficients of skewness and kurtosis of the distributions of wind speeds show a downward trend for all 3 sites.

8

Elastic Distortional Buckling of Thin-Walled Bars of Closed Quadratic Cross-Section

Kujawa M., Szymczak C.

Mechanics and Mechanical Engineering

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2013

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Vol. 17, nr 2

119--126

EN

In this study a thin–walled bar with closed quadratic cross-section is considered. The elastic stability of axially compressed bar related to the cross–section distortion is investigated. The governing differential equation is derived with aid of the principle of stationary total potential energy. The critical load for the simply supported bar is found in analytical form and it is compared with the FEM solution. Sufficient accuracy of the results is worth of noticing.

9

Innowacyjne wykorzystanie energii słupa wody

Starzomska M., Piotrowski J. Z., Szewczyk S.

Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska

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2012

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z. 59, nr 2/II/II

725--732

PL

W referacie przedstawiono urządzenie pozwalające na skuteczne pozyskiwanie energii z niewielkich cieków wodnych, w których nieopłacalne lub niemożliwe jest zastosowanie typowych turbin wodnych. Przedstawiono ideę działania urządzenia. Porównano wielkość uzyskanej energii dla tradycyjnego sposobu pozyskiwania energii z wody (przy użyciu turbin wodnych) i przy wykorzystaniu zaproponowanego urządzenia.

EN

This article presents a device which allows to extract energy from the streams where it is impossible or uneconomical to use conventional water turbines. Traditional way of obtaining energy from a water courses (using a water turbine) was compared witch a method which involves our device. The paper also shows the concept of the device.

10

Energy analyses in initiation and propagation of outbursts of coal and gas

Xue S., Yuan L.

AGH Journal of Mining and Geoengineering

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2012

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Vol. 36, no. 3

435-441

EN

The initiation and propagation of outbursts of coal and gas can be considered to be an energy conversion process, i.e. the release and dissipation of the potential energy contained in coal and gas. The release of potential energy may be due to strain energy of coal, expansion of free pore gas, and desorption of gas from coal; while the energy dissipation or conversion may take the forms of coal fragmentation and coal movement. This paper analyses the release and dissipation of the potential energy to gain a better understanding and estimate of outburst risk and intensity.

PL

Inicjacja i propagacja wyrzutów węgla i gazu może być postrzegana jako proces przemiany energii, tzn. uwolnienie i rozpraszanie potencjalnej energii zawartej w węglu i gazie. Uwolnienie potencjalnej energii może być wynikiem energii odkształceniowej węgla, rozszerzenia wolnych gazów porowych oraz desorpcji gazu z węgla; natomiast rozpraszanie energii lub jej przemiana może obrać formę fragmentacji węgla lub przemieszczania się węgla. Niniejsza publikacja analizuje uwalnianie i rozpraszanie energii potencjalnej dla lepszego zrozumienia i oceny ryzyka i intensywności wybuchu.

11

Concept of recrystallization modelling based on the potential energy hypersurface.

Kaczmarek J.

Rudy i Metale Nieżelazne

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2000

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R. 45, nr 4

244-250

EN

In this paper a model of recrystallization is introduced. The model is based on the potential energy hypersurface. The concept of the presented approach consists of development of a notional system which would be helpful in describing more fine properties of this phenomenon. In particular, introduced notions related to the potential energy hypersurface allow the modelling the recrystallization from complex structures of defects and dislocations. Structures of this kind are present within shear bands. Complicated picture of the dynamical recrystallization gives premises for presented in this paper discrete-continuum way of modelling of mentioned phenomena. Discrete part of this description is aimed to determine criteria for detection of nuclei of recrystallization and conditions for growing. The case of recrystallization by coalescence of grains is also discussed.

PL

W niniejszym opracowaniu wprowadzono model rekrystalizacji oparty na potencjalnej energii superpowierzchni. Przedstawione podejście składa się z systemu pojęciowego pomocnego w opisie subtelniejszych własności tego zjawiska. Wprowadzone pojęcia, pokrewne potencjalnej energii superpowierzchni, pozwalają zwłaszcza na modelowanie rekrystalizacji ze złożonych struktur defektów i dyslokacji. Struktury tego rodzaju są obecne wewnątrz pasm ścinania. Złożony obraz dynamicznej rekrystalizacji daje przesłanki do przedstawionej w tym opracowaniu, drogi nieciągłego continuum modelowania wzmiankowanych zjawisk. Nieciągła część tego opisu zmierza do określenia kryteriów dla wykrycia zarodków rekrystalizacji i warunków wzrostu. Wzięto także pod uwagę możliwość rekrystalizacji przez koalescencję krystalitów.