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1
Content available remote

New Concepts of the Study of an Infinite Beam on Elastic Foundation Based on the Distribution Theory

100%
Felis J., Kasprzyk S.
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vol. 125
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issue 4A
A-190-A-196
EN
The new approach to investigation the bending of the infinite length beam on the elastic foundation, applying the theory of distributions, is presented.
2
Content available remote

Analytical Solutions of Excited Vibrations of a Beam with Application of Distribution

80%
Kozień M.
Acta Physica Polonica A
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2013
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vol. 123
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issue 6
1029-1033
EN
In the paper, the analytical solutions of excited vibrations of the Bernoulli-Euler type beam in general case of external loading function is analyzed. The distribution theory is applied to formulate solution when the external functions are the concentrated-force type or the concentrated-moment type. Moreover, two types of excitation in time domain, harmonic and pulsed, are considered. Due to the superposition rule which can be applied in the analyzed linear case, any combination of external loading function can be formulated. The strict analytical solutions are shown for the case of simply supported beam. Describing the external load in the form of concentrated moments makes possible the analytical simulation of the reduction of vibrations of a beam by application of the piezoelectric elements which are in practice the source of external moment-type excitation put in relatively small area of action.
3
Content available remote

Preisach Images of a Simple Mechanical System

80%
Gutowski M., Markovskyi S., Chyao A.
Acta Physica Polonica A
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2013
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vol. 123
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issue 1
13-15
EN
This work is an an early stage of a larger project aiming at answering the question whether or not the Preisach map is really fingerprinting magnetic materials. More precisely, we are interested whether the Preisach model of magnetic hysteresis indeed contains any physics or is just a convenient modeling tool. To this extent we study a very simple mechanical system, thus fully tractable, subjected to the external force. Despite of its simplicity, our model captures all the fundamental features of real magnetic materials, namely their hysteretic behavior, coercivity, remanent magnetization, and saturation at high fields. Both the overall shape of major hysteresis loop as well as first order reversal curves are reproduced quite correctly; they are very similar to those observed in magnetic materials. The model essentially consists of a single, spring loaded, rigid and rotative bar with non-zero friction torque. The length of a projection of this bar onto the direction of an external force is identified with magnetization. The friction torque and the spring constant are the only freely adjustable parameters of our model. Here we investigate, and present, their influence on the inferred Preisach maps.
4
Content available remote

Simulation of Control Algorithm for Active Reduction of Transversal Vibrations of Beams by Piezoelectric Elements Based on Identification of Bending Moment

80%
Kozień M., Ścisło Ł.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1A
A-56-A-61
EN
Application of piezoelectric elements to active reduction of bending vibrations of the beams is known well in the literature. During vibrations, an external excitation may vary in the time domain, including its form in the frequency domain. It should have influence on their response. The problem of proper selection of the control parameter in the control algorithm used to reduce vibrations arises. In the article, simulations of a control algorithm based on detection of bending moment are analytically tested. The solution for the transient type of vibrations are obtained by the finite difference method (FDM). Analysis for two separated natural modes was performed. The analysis shows the possibility to design a control algorithm based on detection of the bending moment.
5
Content available remote

Analysis of a Skid Type Landing Gear of a Rotary Wing UAV by Experimental and Numerical Methods

61%
Yildirim O., Günay E., Anil Ö., Aygün C.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1170-1175
EN
The objective of this study was to analyze the results obtained from tests done by simulating the crash landing of a rotary wing unmanned air vehicle with a skid type landing gear. The experimental and computational methods were used in the simulation tests. In the first portion of the test; namely with the experimental method, the impact loads induced by the simulated crash landing and the stresses, strains, deformations generated by these loads, were recorded by drop test apparatus. In the second portion of the test with the computational method, free falling of the skid type landing gear was modeled and crash landing test was simulated numerically by using ANSYS code. Experimental methods were applied on four skid landing gear specimens with different shapes. Each of the test samples used in the following test was evolved because each sample was developed and redesigned based on the feedback results obtained from the former test.The first three test specimens were manufactured from 2024 T3, 7075 T6 and 6061 T6 aluminum alloys respectively and all of them were curved in Π-form with a solid cross section. The last and fourth specimen was also manufactured from 6061 T6 aluminum alloy and it was curved in a hollow semi-circle form (∩-form). It is concluded that the last and fourth developed specimen was the best in absorbing the impact energy and enduring the crash.
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