Petru Florin MINDA


19-90 DETERMINAREA GRAFO-ANALITICĂ PE BAZA FRECVENŢEI PROPRII A ADÂNCIMII DEFECTULUI LA BARE ÎNCASTRATE

GRAPHIC-ANALYTICAL METHOD FOR DAMAGE DEPTH
DETERMINATION BASED ON NATURAL FREQUENCIES
AT CANTILEVER BEAM
The paper presents research results of authors in determining of the
damage depth for a cantilever beams by using natural frequencies. A graphicanalytical
method is proposed which permit to evaluate the damage depth and
localize the position of the damage on the beam length. The method is based
on results obtained from the numerical modal analysis for the first ten modes of
vibration. Experimental tests have confirmed the method and the results have
application in non-destructive examination based on vibration analysis.
Keywords: natural frequencies, defect, depth, bar mixer
Cuvinte cheie: frecvenţe proprii, defect, adâncime, bară încastrată

90 DETERMINAREA GRAFO-ANALITICĂ PE BAZA


19-97 LOCALIZAREA DEFECTULUI ÎN BARE ÎNCASTRATE UTILIZÂND INDICELE ABATERII RELATIVE A FRECVENŢELOR PROPRII

LOCALIZATION OF DAMAGE IN CANTILEVER BEAMS USING
THE RELATIVE SHIFT IN NATURAL FREQUENCIES
This paper presents a method to locate the damages in cantilever
beams based on relative shift in natural frequencies. This method takes in to
account the particular manner in which the natural frequencies of the first then
modes change due to the occurrence of damage. The measured frequencies
changes are a compared with values contained in a databases, determined on
models using the finite element method. For these databases we consider a
large number of damages locations. By comparing the changes in frequencies
obtained trough measurements with those determined on models, for the first
ten vibration modes, it was possible to locate damages with high accuracy.
Keywords: vibration, bar mixer, frequencies, detecting defects
Cuvinte cheie: vibraţii, bară încastrată, frecvenţe proprii, detectarea
defectelor

97 LOCALIZAREA DEFECTULUI ÎN BARE ÎNCASTRATE


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

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

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