Wyniki wyszukiwania - BazTech

1

Deceleration and deformation during dynamic load of model longitudinals – real conditions and simulation

Hadryś D., Kubik A., Stanik Z., Łazarz B.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2019

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z. 102

53--64

EN

The manner and degree of taking over impact energy by the passive safety elements of the vehicle body is the basis for providing conditions for the survival of people using the means of transport (driver and passengers). The elements specially designed for this purpose in the self-supporting body are longitudinals. Their energy-absorbing properties are designed by using a specific shape, by using appropriate connections of their components and by choosing the right material. Determining the degree to which the vehicle (body) ensures safety during collision requires testing. The most complex and expensive tests are the ones carried out on a complete real object (whole vehicle). The solution worth considering is a bench test of individual body elements designed as energy-consuming (for example, longitudinals). In addition, it is also possible to carry out computer simulations in this area. The purpose of this article was to present and compare the results of dynamic studies on model energy-consuming real objects and compare the results obtained this way with the results of computer simulation in the same range. The scope of work was adopted on this basis: passive safety, model energy-absorbing elements of steel self-supporting vehicle body, dynamic tests, computer simulations. For the purpose of this study, a model of vehicle passive safety elements (model longitudinals) was designed for which dynamic tests were carried out on a specially designed test stand (speed of the hammer was up to 9.7 m/s, impact energy was up to 23.6 kJ). This test stand enabled registration of the deceleration during impact and deformation of the tested object. Next, computer simulations were carried out for geometrically and material-identical models. On the basis of the conducted tests, it was found that it is worth considering the replacement of collision tests of the whole vehicle by tests of its individual components. These tests can also be supported by computer simulations.

2

Sliding mode control for longitudinal aircraft dynamics

Iskrenovic-Momcilovic O.

Journal of Automation Mobile Robotics and Intelligent Systems

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2018

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Vol. 12, No. 3

55--60

EN

The control of the longitudinal aircraft dynamics is challenging because the mathematical model of aircraft is highly nonlinear. This paper considers a sliding mode control design based on linearization of the aircraft, with the pitch angle and elevator deflection as the trim variables. The design further exploits the decomposition of the aircraft dynamics into its short-period and phugoid approximations. The discrete-time variable structure system synthesis is performed on the base of the elevator transfer function short-period approximation. This control system contains a sliding mode controller, an observer, based on nominal aircraft model without finite zero and two additional control channels for the aircraft and for the aircraft model. The realised system is stable and robust for parameter and external disturbances.

3

Ocena cech litogenetycznych piaskowców fliszowych na podstawie badań ultradźwiękowych

Kłopotowska A., Łukasiak D.

Przegląd Geologiczny

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2017

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Vol. 65, nr 3

177--182

EN

Non-destructive ultrasonic tests were used to determine the lithogenetic features responsible for the anisotropy of flysch sandstones. The studied material consisted of the Godula and Zakopane sandstones. These rocks are characterized by significant anisotropy of the geomechanical properties. As a result of ultrasonic testing the characteristic directions ofpropagation of longitudinal waves were determined and subsequently correlated with the microscopic image of thin sections as well as the evident orientation ofjoints observed in situ. The analysis shows that the recorded changes in the propagation of ultrasonic waves indicate the privileged direction resulting from both the orientation of mineral grains and spatial orientation of microcracks. It has a bearing on the direction of turbidity currents in the sedimentary basin and the variable stress field during the formation of the Carpathians.

4

Wpływ metod naprawy podłużnicy na bezpieczeństwo bierne pojazdu osobowego

Węgrzyn T., Hadryś D., Świerkosz M.

Aparatura Badawcza i Dydaktyczna

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2013

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T. 18, nr 2

141--147

PL

W artykule przedstawiono zagadnienia dotyczące naprawy powypadkowej podłużnie samonośnego nadwozia pojazdu, wykonanych ze stopów aluminium. Przeprowadzono badania o charakterze dynamicznym i porównano wyniki dla elementów nowych i naprawionych. Podjęto próbę odpowiedzi na pytanie, która z zaproponowanych metod naprawy jest lepsza w aspekcie bezpieczeństwa użytkowników pojazdu.

EN

The article presents the issues of post-accident repair of carbody longitudinal, which are made by aluminum alloys. The dynamic tests were carried out. Results for new and repaired parts were compared. It attempts to answer the question, which of the proposed repair method is better in terms of safety of the vehicle users.

5

Effect of longitudinal surface roughness on the behaviour of squeeze film in a spherical bearing

Andharia P. I., Deheri G. M., Gupta J. L.

International Journal of Applied Mechanics and Engineering

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2001

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Vol. 6, no 4

885-897

EN

Efforts have been made to study the effect of longitudinal surface roughness on the performance of a hydrodynamic squeeze-film between a non-rotating spherical surface and a hemispherical bearing under a steady load using the general stochastic analysis without using a specific probability distribution for describing random roughness, It is assumed that the bearing surface as well as the surface of the approaching sphere have random roughness, which is distributed throughout the surfaces. The stochastic film thickness characterizing the roughness is considered to be symmetric with non-zero mean ('alpha') and variance ('sigma'2). In order to get the expression for pressure the modified Reynolds equation is solved. Then by making use of this expression we obtain the expressions for load carrying capacity, which in turn is used to find the expression for response time. These expressions are numerically computed and the results are presented graphically as well as in tabular form. It is observed that the composite roughness of the surfaces affects the performance of the bearing significantly.