Andrea Amalia MINDA

32-74 FILTRAREA ŞI CORECTAREA VALORILOR FRECVENŢELOR PROPRII ALE GRINZII DUBLU ÎNCASTRATE EXPUSĂ INFLUENŢEI VARIAŢIILOR DE TEMPERATURĂ

Această intrare a fost publicată în 2017 Volumul 32 și etichetată Andrea Amalia MINDA Gilbert Rainer GILLICH Horia FURDUI la de

FILTERING AND CORRECTION OF NATURAL
FREQUENCY VALUES FOR A DOUBLE-CLAMPED BEAM
SUBJECTED TO TEMPERATURE CHANGES
This paper presents the effect of temperature changes on the natural frequencies of beams. These may have perfect or elastic restraints at ends. A temperature increase produces compressive stress and consequently a natural frequency decrease. We contrived mathematical relations to evaluate the effect of temperature for the cases of perfect rigid as well as for elastic restraints. If the beam is imperfect, i.e. anisotropic, non-homogeneous or not strength in the initial state, a correction term has to be employed to accurately find the frequencies. The correction method is also presented.
Keywords: natural frequencies, filtering, correction algorithm, temperature
Cuvinte cheie: frecvenţe proprii, filtrare, metodă de corecţie, temperatura

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29-77 INFLUENŢA DEFECTULUI ASUPRA MODIFICĂRII TEMPERATURII CRITICE LA FLAMB

Această intrare a fost publicată în 2016 Volumul 29 și etichetată Andrea Amalia MINDA Gilbert Rainer GILLICH Horea FURDUI la de

DAMAGE INFLUENCE ON THE CRITICAL BUCKLING
TEMPERATURE
This paper presents the influence of a transverse damage in a doubleclamped
beam upon the critical buckling temperature. First, the buckling
temperatures and subsequent loads are analytically investigated on an intact
prismatic beam, together with the dynamic behavior in terms of the natural
frequencies. Afterwards, the effect of a transverse damage is considered, and a
relation expressing the frequency alteration due to the crack is provided. To
prove the relation’s validity a finite element analysis was performed for some
particular cases, and the results compared with those obtained analytically. The
investigation did show a good concordance between the results obtained in the
two ways, proving the correctness of the analytical approach.
Keywords: double-clamped beam, damage, thermal buckling
Cuvinte cheie: grindă dublu încastrată, defect, flambaj, temperatură
critică

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27-83 INFLUENŢA EFECTULUI TERMIC ASUPRA FRECVENŢELOR PROPRII ALE GRINZILOR ÎNCASTRATE LA AMBELE CAPETE

Această intrare a fost publicată în 2015 Volumul 27 și etichetată Andrea Amalia MINDA Gilbert Rainer GILLICH Horea FURDUI la de

THE EFFECT OF THERMAL LOAND ON THE NATURAL FREQUENCIES OF DOUBLE-CLAMPED BEAMS
The natural frequencies of double-clamped beams are influenced by environmental conditions and operational loads. For instance the temperature induces axial loads due to restraint displacements, which lead after a critical temperature increase to buckling. This paper clarifies the effect of external loads on the natural frequencies of beams.
Keywords: thermal loads, buckling, Euler-Bernoulli beam, natural frequency
Cuvinte cheie: încărcări termice, flambaj, grindă, frecvenţe proprii

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26-38 INFLUENŢA TEMPERATURII ASUPRA FRECVENŢELOR PROPRII ALE ELEMENTELOR DIN STRUCTURI CU ZĂBRELE

Această intrare a fost publicată în 2014 Revista Volumul 26 și etichetată Andrea Amalia MINDA Gilbert Rainer GILLICH Horea FURDUI la de

TEMPERATURE EFFECT UPON THE NATURAL FREQUENCIES OF THRUSS ELEMENTS
In this paper we analyze the effect of temperature upon the natural frequencies of truss elements. Temperature changes influence the Young’s modulus in the sense that it decreases with increasing temperature, consequently structural elements frequencies decrease. However, we demonstrate in this paper that the frequency changes due to temperature in natural environment are very small and do not dramatically influence the structures dynamic behavior.
Keywords: temperature, Young modulus, frequency, truss structures

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22-20 ANALIZA FEM A SISTEMELOR DE IZOLARE SEISMICĂ CU SUPRAFAŢA DE ALUNECARE GENERATĂ DE FUNCŢII POLINOMIALE

Această intrare a fost publicată în 2012 Volumul 22 și etichetată Andrea Amalia MINDA Claudiu IAVORNIC Gilbert Rainer GILLICH Nicoleta GILLICH Ştefania Camelia JURCĂU la de

Earthquake isolation systems are devices located at the base of
overhead structures (civil works), which have the goal to take off the oscillating
period of this compared with ground, during an earthquake and decrease the
transmitted energy using frictional dissipation. The results of the study
presented of this paper relieve the possibility of using sliding surfaces
generated by polynomial functions by using an intermediate neoprene element
between the sliding surface and the slider.
Cuvinte cheie: izolator seismic, pendul cu fricţiune, neopren, funcție
polinomială, analiză FEM
Keywords: seismic isolation, friction pendulum, neoprene, polynomial
function, FEM analysis

20 ANALIZA FEM A SISTEMELOR DE IZOLARE SEISMICĂ

22-19 SISTEME INOVATIVE DE IZOLARE SEISMICĂ BAZATE PE DISIPAREA ENERGIEI PRIN FRECARE. ANALIZA STATICĂ

Această intrare a fost publicată în 2012 Volumul 22 și etichetată Andrea Amalia MINDA Claudiu IAVORNIC Gilbert Rainer GILLICH Petru Florin MINDA Ştefania Camelia JURCĂU la de

Friction pendulums are used to reduce forces transmitted from the
ground to buildings, in order to diminish or avoid earthquakes loss, by
permitting relative displacements between the isolated structure and earth
during seismic actions. The result consists in reduced accelerations and
consequently reduced inertia forces. In this paper we present a new approach
regarding implementation of a friction pendulum having the sliding surface
profile based on a polynomial function of superior order. The new device
implies the use of an elastic element between the slider and the sliding surface.
Static and dynamic analyses performed using the finite element method
confirmed that the use of an elastomeric element is suitable for this purpose.
Cuvinte cheie: pendul cu fricţiune, suprafaţa de alunecare, funcţii
polinomiale, element elastomeric
Keywords: friction pendulum, sliding surface, polynomial functions,
elastomeric element

19 SISTEME INOVATIVE DE IZOLARE SEISMICĂ

22-17 SISTEME INOVATIVE DE IZOLARE SEISMICĂ BAZATE PE DISIPAREA ENERGIEI PRIN FRECARE. MODEL ANALITIC

Această intrare a fost publicată în 2012 Volumul 22 și etichetată Andrea Amalia MINDA Claudiu IAVORNIC Gilbert Rainer GILLICH Petru Florin MINDA Ştefania Camelia JURCĂU la de

In this paper we present an innovative system for seismic isolation
based on frictional energy dissipation. While classical friction pendulum
bearings contain one or more cylindrical or spherical sliding surfaces, they
provide just pairs of two parameters controlling the dynamic behavior of a
structure isolated by this kind of device. In this paper we are implementing
friction pendulums having the sliding surface profile based on a polynomial
function of superior order. This seismic isolation system permit a greater
flexibility in controlling the oscillations of the upper structure, in terms of
displacements or dissipated energy, by using three parameters to control the
force-displacement relation.
Cuvinte cheie: pendul cu fricţiune, suprafaţa de alunecare, funcţii
polinomiale, energia disipată
Keywords: friction pendulum, sliding surface, polynomial functions,
disipated energy

17 SISTEME INOVATIVE DE IZOLARE SEISMICĂ BAZATE