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1

Determining parameters to optimize the pulling force for the luffing jib tower cranes by Taguchi method

Duong Truong Giang

Archive of Mechanical Engineering

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2023

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LXX, nr 3

387--407

EN

The presented problem consists in optimizing the pulling force of the luffing jib tower cranes, in order to reduce power and save energy by determining reasonable geometrical parameters such as placement of pulley assemblies, position of jib pin, and jib length. To determine the optimal parameters, a mechanical model was developed to calculate the pulling force of the research object. Then, the Taguchi method and Minitab software were applied to evaluate the influence of the parameters. The objective function was the minimum pulling force of the luffing jib. The calculation results show that the position of the pulley assembly used to pull the jib is the most influential factor on the objective function accounting for 81.15%, the less significant factors are the jib length, the pin position of the jib, and the pulley assembly that changes the direction of the load lifting cable. The result of the test presented in the article allowed for determining the rational parameters, and the optimal position of the pulley assemblies on the top of the crane. In the case of the pulley assembly located at the top of the crane, one obtains the optimal height of the crane head H≈0.4 L c.

2

Rotors of vertical-axial wind turbines assembled in bearings and aerodynamic characteristics of a blade with unclosed wing profile

Panda Anton, Rozhkova Lyudmila, Kuznetsov Eduard, Nahornyi Volodymyr

Management Systems in Production Engineering

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2022

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nr 4 (30)

298--303

EN

In world practice, traditional blades used in high-speed wind turbines, both horizontal-axial and vertical-axial, have a wing-shaped profile. However, for horizontal-axial wind turbines, blades with such a profile have a fairly narrow range of operating values of the angle of attack of the incoming air flow and a low value of the moment of pulling from place. As for vertical-axial wind turbines, the self-starting of the rotor with wing blades is completely absent and additional devices are needed to start the rotor into operation. In order to ensure the selfstarting of the rotor and the operation of the wind turbine at high and low wind speeds, a new shape of the blade profile was developed, called non-closed wing profile. The concept of the development is that the blade should have a configuration in which the pulling force is involved at the beginning of the movement, and then, with the establishing of the movement, a lifting force would arise, which acquires a prevailing character in the operating mode. The article presents the results of experimental studies of the aerodynamic characteristics of the developed non-closed wing blades. One of the results obtained is to determine the effect of the thickness of the blade profile on the range of values of subcritical angles of attack of the incoming air flow and the differences between the nature and range of changes in the coefficients of lifting force and pulling force in a traditional wing blade and a blade with a non-closed wing profile. Studies of the rotor model of a vertical-axial wind turbine with non-closed wing blades have confirmed the presence of its self-starting and operability even at low wind speeds.

3

Assessment of the change in the rolling resistance of a wheel in varied field conditions

Białczyk W., Brennensthul M., Cudzik A., Czarnecki J.

Agricultural Engineering

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2015

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Vol. 19, No. 4

5--13

EN

The paper presents the research results concerning the rolling resistance of a wheel on agricultural surfaces. Research on traction was carried out in field conditions with the use of a mobile stand; a wheel with 9.5-24 tyre was investigated; values of the rolling resistance and the pulling force were analysed with reference to the wheel slip. A type of surface (soil, sod), its compaction and the vertical load of a wheel were assumed as factors. Based on the obtained results, it was proved that the rolling resistance was by approx. 30% higher on soil than on sod. Differences resulting from the variety of surfaces were higher than the differences caused by various values of their compaction (did not exceed 25%). No significant impact of compaction changes on the rolling resistance and pulling force values were proved but a considerable increase of the rolling resistance value along with the decrease of its compaction were determined. Moreover, it was proved that the increase of the vertical load of a wheel resulted in the increase of the rolling resistance and the pulling force on both grounds but these changes were higher on soil than on sod.

PL

W pracy przedstawiono wyniki badań dotyczące oporu przetaczania koła ciągnika na podłożach rolniczych. Badania trakcyjne wykonano w warunkach polowych z wykorzystaniem mobilnego stanowiska, badano koło z oponą 9.5-24, analizowano wartości oporu przetaczania oraz siły uciągu w odniesieniu do poślizgu koła. Jako czynniki przyjęto rodzaj podłoża (gleba, darń łąkowa), jego zwięzłość oraz obciążenie pionowe koła. Na podstawie uzyskanych wyników wykazano, że na glebie wartości oporu przetaczania były o ok. 30% wyższe niż na darni. Różnice wynikające z odmienności podłoży były większe niż różnice powodowane różnymi wartościami ich zwięzłości (nie przekraczały 25%). Na darni nie wykazano istotnego wpływu zmian zwięzłości na wartości oporu przetaczania i siły uciągu, natomiast na glebie stwierdzono znaczny wzrost wartości oporu przetaczania wraz ze spadkiem jej zwięzłości. Ponadto wykazano, że zwiększanie obciążenia pionowego koła skutkowało wzrostem oporu przetaczania i siły uciągu na obu podłożach, przy czym na glebie zmiany te były większe niż na darni.

4

Railway crossing with adjustable pulling force as function of loading

Buratowski T., Targosz J.

Transport Problems

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2009

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T. 4, z. 3, cz.1

113-123

EN

In this paper presents the concept of controlling the pulling force as a function of loading of railway crossing that was modelled as a discrete-continuous system. Two elements figure are described as continuous systems: elastomer support and pull-strings. Tension in pull-strings is adjusted in relation with railway crossing loading.

PL

W pracy przedstawiono koncepcje regulowanej siły naciągu liny zastosowanej w wibroizolowanym przejeździe kolejowo drogowym w funkcji obciążenia. Regulacje oparto o model dyskretno ciągły systemu złożonego z elementu elastomerowego oraz liny traktowanej jako układ ciągły.