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1

The use of modal analysis to examine the lattice structure

Żółtowski Mariusz, Jeleniewicz Katarzyna

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2019

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Vol. 28, No. 3

332--344

EN

Steel structures are subject to large dynamic loads clearly reflected by generated vibration processes. The vibrations may affect state of serviceability of structures by lowering comfort of persons working there as well as possible reaching the level hazardous to safety of the structures. The effect of vibrations to structure is mainly manifested by additional stresses in a given cross-section, which are summed up with those resulting from static loads. The dynamic loads may cause damaging effects in buildings of various structural types or even lead to their destruction. Judging the necessity of improving the quality assessment methods of building structures for purposes of estimation of their state as well as safety factors for lattice structures, the author of this work undertook an attempt to investigate destruction process of selected object by using the modal analysis method.

2

Effect of Blades Settings on Rotor Dynamics

Mitura A., Gawryluk J., Teter A., Warmiński J.

Machine Dynamics Research

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2018

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Vol. 42, No. 2

73--79

EN

In the paper, experimental and numerical studies of dynamics of a rotor composed of a rigid hub and three laminated blades with an embedded active piezoelectric actuators are discussed. The rotor is excited by periodic torque imposed to the hub. The dynamic response for various preset angles of the blades has been tested experimentally on the basis of signals recorded from strain gauges. The experimental results have been compared with a numerical ﬁnite element model developed in Abaqus software. The eigenvalue problem has been solved, and the natural frequencies and corresponding modes have been compared with experimental tests.

3

A procedure for forecasting the results of induced seismicity on buildings following exceptionally strong mine tremors

Zembaty Z., Bobra P., Paprotny M., Póda A., Bubała C., Kuś J.

Czasopismo Techniczne. Budownictwo

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2016

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Y. 113, iss. 3-B

145--153

EN

Sometimes, deep mining introduces particular seismic risk to buildings on the surface; therefore, special procedures are needed to assess the safety limits of ground motion. This paper demonstrates such a procedure for use when the standard approach fails to properly asses intensity. Peak velocity is chosen to measure seismic intensity. Forecasted and past seismicity is compared with structural damage assessments to make a decision allowing safe mining in a given location.

PL

Zdarza się, że górnictwo podziemne stwarza podwyższone ryzyko sejsmiczne dla obiektów budowlanych, co wymaga specjalnych procedur oceny ograniczeń akceptowalnego ruchu podłoża. Niniejszy artykuł opisuje taką specjalną metodologię, gdy standardowe podejście nie może być zastosowane. Jako miarę sejsmicznej intensywności wybrano prędkość ruchu podłoża. Prognozowana i dotychczasowa sejsmiczność są porównane z uwzględnieniem uszkodzeń budowli w celu umożliwienia bezpiecznej eksploatacji dla zabudowy powierzchniowej.

4

Investigations of harbour brick structures by using operational modal analysis

Żółtowski M.

Polish Maritime Research

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2014

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nr 1

42--53

EN

Historic harbour brick objects are subject to large dynamic loads clearly reflected by generated vibration processes. The vibrations may affect state of serviceability of structures by lowering comfort of persons working there as well as possible reaching the level hazardous to safety of the structures. The effect of vibrations to structure is mainly manifested by additional stresses in a given cross-section, which are summed up with those resulting from static loads. Moreover often occur consequences associated with environmental conditions and fatigue of materials which accelerate destruction of the objects. Therefore the dynamic loads may cause damaging effects in buildings of various structural types or even lead to their catastrofic destruction. Judging the necessity of improving the quality assessment methods of building structures for purposes of estimation of their state as well as safety factors for brick structures (see PN-B- 03002 standard, p.3.1.3 and 4.6), the author of this work undertook an attempt to investigate destruction process of selected building structures by using the method of operational modal analysis.

5

Model based predictive control of guyed mast vibration

Błachowski B.

Journal of Theoretical and Applied Mechanics

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2007

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Vol. 45 nr 2

405-423

EN

The purpose of this work is to present an algorithm for optimal vibration control of guyed masts and an example of its application to a numerical simulation. The objective of the proposed contral system is to minimize amplitudes of transverse vibrations of the top of a mast induced by wind pressure acting on the structure. Control forces are assumed to be physically realized through changes of tension in guy cables, supporting the mast. The only required measurements are velocities of guy cables at the anchor-points. On the basis of those, a complete state of deformation of the structure is obtained by using the Kalman filter. The Davenport spectral density function is adopted as a model of the stochastic action of the wind.

PL

Celem pracy jest algorytm i jego przykładowe zastosowanie do symulacji numerycznej optymalnego sterowania drganiami masztów z odciągami. Zadaniem układu sterowania jest minimalizacja amplitud poprzecznych drgań wierzchołka masztu wywołanych oddziaływaniem wiatru. Realizacja sił sterowania odbywa się poprzez zmianę naciągu w odciągach masztu. Estymacja pełnego stanu deformacji konstrukcji na podstawie pomiaru jedynie prędkości w punktach zakotwienia odciągów uzyskana jest poprzez wykorzystanie filtru Kalmana. Do zamodelowania losowego oddziaływania wiatru użyto funkcję gęstości widmowej Davenporta.

6

A survey of modern systems of vibration reduction of civil engineering structures

Lewandowski R.

Vibrations in Physical Systems

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2006

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Vol. 22

37--45

7

Acoustic Radiation by Set of L-Jointed Vibrating Plates

Kozień M., Wiciak J.

Molecular and Quantum Acoustics

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2005

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Vol. 26

183-190

EN

Sound radiation from a L-jointed plates is investigated. Of particular interest is the acoustic pressure level at the control point at the distance of 1 m from the two plate surfaces. Two approaches were utilised, the FEM method was applied in the analysis of structural vibrations and the radiation efficiency in the analysis of acoustic phenomena. The other approach was the statistical energy analysis, referred to as SEA.

8

Hybrid method of evaluation of sounds radiated by vibrating surface elements

Kozień M. S.

Journal of Theoretical and Applied Mechanics

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2005

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Vol. 43 nr 1

119--133

EN

The paper provides the theoretical background of a hybrid method to be applied in engineering evaluation of sound radiation by vibrating surface elements. The intensity vector is obtained at a selected point in the acoustic medium surrounding the vibrating element. For convenience, certain assumptions are made for the purpose of far-field analysis, which makes the method allow for estimation of radiated acoustic pressure. The method is the verified experimentally. Vibrations of structural elements can be predicted theoretically using finite element approach or from the measurement of vibrations of real structures.

PL

W pracy przedstawiono podstawy teoretyczne metody hybrydowej służącej inżynierskiemu oszacowaniu promieniowania akustycznego przez drgające powierzchniowe elementy strukturalne. Metoda umożliwia wyznaczenie wektora natężenia akustycznego w wybranym punkcie ośrodka otaczającego drgający element. Przy pewnych założeniach upraszczających (pole dalekie) możliwa jest estymacja promieniowanego ciśnienia akustycznego. Metoda została zweryfikowana doświadczalnie. Drgania elementu strukturalnego mogą być wyznaczone na drodze teoretycznej metodą elementów skończonych bądź pochodzić z pomiarów drgań rzeczywistych struktur.