The essential phenomenon accompanying hoisting machines such as overhead cranes is the occurring of negative vibrations. Due to the characteristic beam type construction of the load carrying structure, they were particularly important in the case of heavy loads, causing considerable stress values, both in the ropes and girder structure. These values are described by dynamic coefficient examined in this study. Because of the problem importance, a different approach to modeling the process of lifting the load is proposed, mainly due to the dynamic model of rope applied. It proposes models of the rope and lifting mechanism, using both the modified Bouc-Wen model as well as a classical model of Kelvin-Voigt as a model of rope in the hoisting mechanism, where the value of dynamic factor has been verified. It helps to specify the multiplicity of overloading the structure and impact of rope modeling method according to its value. The models for the test of hoisting machines proposed in the paper include the modeling of the wire rope in the hoisting mechanism and the influence of ropes modeling method on a dynamic factor.
Summary. The article presents the results of numerical analysis whose aim was to compare the basic dynamic and strength parameters of lightweight load-carrying crane structures made of aluminium alloys and steel. The analysis covered the typical construction of workshop cranes with a span of 3 to 5 meters, girders in the form of an Ibeam and maximum load capacities amounting to 5 tons. The values of stresses, deflections and natural frequencies were compared and then matched with the masses of the various structures. In the simulation a girder model was used and computed by the finite element method. BADANIA MODELOWE WYKORZYSTANIA STOPÓW ALUMINIUM W USTROJACH NOŚNYCH LEKKICH SUWNICStreszczenie. W artykule przedstawiono wyniki analizy numerycznej, której celem było porównanie podstawowych parametrów dynamicznych i wytrzymałościowych ustrojów nośnych lekkich suwnic wykonanych z aluminium i stali. Analizie poddano typowe konstrukcje suwnic warsztatowych o rozpiętości od 3 do 5 metrów, o dźwigarach w postaci dwuteownika i maksymalnych udźwigach wynoszących 5 ton. Porównywano wartości naprężeń, ugięć i częstotliwości drgań własnych, a następnie zestawiono je z masami poszczególnych ustrojów. W symulacji wykorzystano model dźwigara obliczany z wykorzystaniem metody elementów skończonych.
Determining the size and quality of transport needs would not be possible without adequate forecasting based on the sales volume or demand for this service from the past periods. Traditional forecasting methods use econometric models that may be subject to serious errors. The use of the methods taking into account the variability of the studied phenomena or more advanced mathematical methods enables to minimize the error. Various methods of artificial intelligence such as a neural network, fuzzy sets, genetic algorithms, etc., have been recently successfully applied. The aim of this paper is to compare three forecasting methods that can be used for predicting the volume of road freight. The article deals with the effectiveness of three prediction methods, namely Winters method for seasonal problems -a multiplicative version, harmonic analysis and harmonic analysis aided by the artificial immune system. The effectiveness of prediction was counted using MAPE errors (main average percentage error). The results of calculations were compared and the best example was presented.
TRAFFIC NOISE EXPERIENCED ON BUSES, TRAMS AND CARS IN THE URBAN AGGLOMERATION OF THE CITY OF KATOWICE Summary. Transport noise is one of the biggest problems faced by urban agglomerations. Therefore, more and more activities are being undertaken related to its reduction. The article attempts to investigate the noise level on public transport vehicles, buses, trams and passenger cars, from the passenger's perspective. The assessment is based on the results of field tests. The study considered wheeled and rail vehicles, including a new generation of buses and tramways, as well as a car subjected to many years of operation. The research was carried out in the city of Katowice. The conducted experiment showed comparable high values for recorded volume levels on trams and buses, as well as a relatively low noise level in the passenger car.
This article presents an approach of numerical modelling of I-beam crane jib, with using the finite element method particularly the most loaded elements at different speeds. One of the possible methods for use in the design process of hoisting dynamics modelling and its effects on the load-carrying structure for the marine jib crane is shown. For proper modelling, the impact of the load and hoisting speed on the load-carrying structure jib, dynamics simulations of hoisting the load using Matlab-Simulink software were carried out and in the field of finite element method. To carry out such a simulation, hybrid calculations had to be applied, where the response from the phenomenological model based on solving a system of differential equations of motion in Matlab-Simulink was used to stimulate the crane I-beam jib during the FEM simulation, which permits to determine dynamic properties of the load-carrying structure for two example different hoisting speeds. The basic strength parameters for a typical light marine jib crane, obtained in the case of static calculations and using the proposed approach between the two computing environments were compared.
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