Marius TUFOI


32-58 MODIFICAREA DISTRIBUŢIEI TENSIUNILOR ÎN ZONA DEFECTULUI ŞI EFECTUL ACESTEIA ASUPRA FRECVENŢELOR PROPRII ALE GRINZII

STRESS DISTRIBUTION ALTERATION IN THE DAMAGED ZONE AND ITS EFFECT ON THE BEAM’S NATURAL FREQUENCIES

 

In this paper the relation to be used for deriving the frequency of a beam with transverse crack is tested against finite elements method (FEM) simulation results. We have first analytically derived the beam deflection and compared with results achieved by means of the FEM simulation. The good concordance was found, thus the FEM model is calibrated. Afterwards, damage of different depth was introduced in the beam and the natural frequencies derived. These values were compared against results attained by applying the proposed relation and a good fit was found.

 

Keywords: beam, damage detection, vibration, natural frequencies, deflection

Cuvinte cheie: grindă, detectarea defectelor, vibraţii, frecvenţe proprii, săgeată

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29-87 INFLUENȚA RIGIDITĂȚII MECANICE ASUPRA FRECVENȚELOR PROPRII DE VIBRAȚIE A CADRELOR METALICE

THE INFLUENCE OF MECHANICAL STIFFNESS ON EIGEN
FREQUENCIES OF VIBRATION AT METAL FRAMES
This paper presents a study regarding the changes of the natural
frequency of trusses due to stiffness increase. The finite element analysis was
performed, considering a constantly increasing of stiffness of frame. In this way,
the correlation between frequency changes in the transversal vibration modes
and stiffness for the studied frames is highlighted.
Keywords: stiffness, eigen frequency, vibration mode, FEM
Cuvinte cheie: rigiditate, frecvente proprii, moduri de vibraţie, MEF

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25-63 EFECTUL DEFECTELOR STRUCTURALE ASUPRA COMPORTAMENTULUI DINAMIC AL GRINZILOR COMPOZITE STRATIFICATE

EFFECT OF STRUCTURAL DAMAGES ON THE DYNAMIC
BEHAVIOUR OF LAMINATED BEAMS
This paper presents results obtained by modal analysis on composite
beam-like structures in healthy and damaged state. The aim is to obtain
damage “signatures” for all possible damage scenarios and to use these data
to assess transversal cracks based on vibration techniques, by involving natural
frequency shifts. The analysis was performed in SolidWorks software for a fivelayer
composite, 30 vibration modes being obtained by numerical simulations.
An example how to interpret the results is shown in the last section of the
paper.
Keywords: damage, finite elements, frequency, simulation, structure
Cuvinte cheie: defect, elemente finite, frecvenţă, simulare, structură
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19-111 METODĂ DE DIMENSIONARE A ELEMENTELOR ACTIVE DIN ALIAJE CU MEMORIA FORMEI AFLATE ÎN COMPONENŢA UNUI ACTUATOR PENTRU UN MODUL ROBOTIC DE PREHENSIUNE

DIMENSIONING METHOD OF SHAPE MEMORY ALLOYS
ACTIVE ELEMENTS OF AN ACTUATOR FOR A ROBOTIC
PREHENSION MODULE
Even it has been recognized that Shape Memory Alloys (SMA) have a
significant potential for deployment actuators, the number of applications of
SMA-based actuators to the present day is still quite small, due to the need of
deep understanding of the thermo-mechanical behaviour of SMA. Thus, the
paper presents a dimensioning method for the electrically heated active
elements of a robotic prehension system in order to obtain maximal stroke and
displacement.
Keywords: actuator, grip strength, shape memory alloy, sizing
Cuvinte cheie: actuator, prehensiune, aliaj cu memoria formei,
dimensionare

111 METODĂ DE DIMENSIONARE A ELEMENTELOR


20-63 STUDII PRIVIND OPTIMIZAREA ROLELOR DE TRAGERE LA TURNAREA CONTINUĂ VERTICALĂ A OŢELULUI

STUDIES REGARDING THE OPTIMIZATION OF
WITDRAWING ROLLERS AT VERTICAL CONTINUOUS
CASTING OF STEEL
This paper presents an optimization method for withdrawal rollers to the
withdrawal plant at vertical continuous casting of steel. Optimizing rollers was
achieved by: use of statistical calculations applied to quantities, experimental
measurements obtained directly from the withdrawal of blanks, using
techniques CAD (Computer Aided Design) and CAE (Computer Aided
Engineering) design, modeling and optimization of cylinders; using finite
element method, FEM for static and dynamic simulations, the behavior of
withdrawal-straightening rolls in continuous casting process for determining
stress, elongation and movements that occur in this process. The study is both
experimental and theoretical, and aims to improve the process of withdrawal of
the semi continuous casting with vertical curvilinear wire of steel, using modern
methods of analysis, design and optimization of mechanical drives.
Keywords: vertical continuous casting, semi-roller drawing optimization,
CAD, CAE
Cuvinte cheie: turnare continuă verticală, semifabricate, role de tragere,
optimizare, CAD, CAE

63 STUDII PRIVIND OPTIMIZAREA ROLELOR DE


20-64 METODE DE OPTIMIZARE A INSTALAŢIILOR DE TRAGERE LA TURNAREA CONTINUĂ ORIZONTALĂ A METALELOR

METHODS OF OPTIMIZATION OF FACILITIES
FOR WITHDRAWAL FROM HORIZONTAL
CONTINUOUS CASTING OF METALS
This paper presents variants of modernization process of withdrawing
the profiles in horizontal continuous casting (HCC) of metals. Horizontal
continuous casting is a modern method of directly obtaining different types of
metallic semi-products by casting without using the laminated lines. As a
method, continuous casting is made by introducing liquid metal with a welldefined
temperature in a tank with water cooled walls, at interior, called
crystallizer and evacuation „wire” of solidified metal. Method of continuous
casting of ferrous and nonferrous metals and steel was imposed because it has
advantages over conventional casting into ingots. These advantages are: the
removal of metal is improved, it is obtaining a semi-finished product with a
superior quality surface, a lower segregation removes, consumption of ingot
molds and cast steel bridges are removed.
Keywords: horizontal continuous casting, semi-optimization methods,
modernization
Cuvinte cheie: turnare continuă orizontală, semifabricate, metode de
optimizare, modernizare

64 METODE DE OPTIMIZARE A INSTALAŢIILOR