highspeed

B U L E T I N U L I N S T I T U T U L U I P O L I T E H N I C D I N I A Ş I
B U L L E T I N O F T H E P O L Y T E C H N I C I N S T IT U T E O F I A Ş I
Tomul LVIII (LXII), Fasc. 2 2012
MACHINE CONSTRUCTION
C O N T E N T S
Pp.
ION BOSTAN (Rep. of Moldova), VALERIU DULGHERU (Rep.
of Moldova) and RADU CIOBANU (Rep. of Moldova),
Analytic description of teeth profile for processional multiplier
(English, Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . .
BOGDAN MUNTEANU (France), ANA-MARIA TRUNFIO
SFARGHIU (France), CONSTANTIN IONUT MATEI
(France), SAW-SEE HONG (France), PIERRE BOULANGER
(France), MARIE-GENEVIEVE BLANCHIN (France), JEAN-
PAUL RIEU (France) and YVES BERTHIER (France),
Correlation between nanomechanical and tribological properties
of healthy and pathological synovial fluids reconstituted from
synoviocyte cultures (English, Romanian summary) . . . . . . . . . . 11
1
VIOREL PALEU, Power loss and temperature computation in highspeed
ball bearings lubricated by oil mist II. Theoretical and
experimental results (English, Romanian summary) . . . . . .
MARCELIN BENCHEA and SPIRIDON CREŢU, Profile
evolution in cylindrical roller bearings, I. Elastic-Plastic
Analysis (English, Romanian summary) . . . . . . . . . . . . . . . . . .
IRINA PELIN, ANA-MARIA TRUNFIO SFARGHIU (France),
PIERRE FARGE (France), AGNES PIEDNOIR (France),
CHRISTOPHE PIRAT (France) and STELLA RAMOS
(France), Mechanical and physicochemical properties of the
deep dentin surfaces (English, Romanian summary) . . . . . . . . .
19
27
37
ANA-MARIA AMANCEA, BENYEBKA BOU-SAЇD (France),
CRISTEL ŞTIRBU, MIHAI GAFIŢANU, MICHÈLE
GUINGAND (France) and CHRISTOPHE BARD (France),
Modelling the knee joint mechanical behaviour using a 3D model.

A numerical simulation solution (English, Romanian summary) . . 45
GEORGE GAVRILĂ and SPIRIDON CREŢU, Wear evolution in
circular contacts in partial slip (English, Romanian summary) ...
53
ANA TUFESCU and SPIRIDON CREŢU, Analysis of stress state
developed contacting elements with non-gauss rough surfaces
(English, Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . . 71
MIHAELA RODICA BĂLAN and SPIRIDON CREŢU, Fatigue
life analysis on roller bearings with various roughnesses of the
active surfaces (English, Romanian summary) . . . . . . . . . . . . .
CONSTANTIN BĂRBÎNŢĂ, ANA URZICĂ and SPIRIDON
CREŢU, On the role played by roughness parameters on
pressure and stress distributions in wheel-rail contact (English,
Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LAURENŢIU SLĂTINEANU, OANA DODUN, LORELEI
GHERMAN, IRINA GRIGORAŞ (BEŞLIU) and VASILE
BRAHA, Roughness parameters of surfaces obtained by
abrasive jet machining (English, Romanian summary) . . . . . . .
ALEXANDRA RAICU, Residual stresses reduction using CAE
analysis in molded polymeric parts (English, Romanian
summary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
CRISTIAN SUCIU, GEORGE ARGHIR, IOAN PETEAN and
CLAUDIU POPA, Effect of sintering temperature on high
alloying manganese steels subjected to abrasive wear (English,
Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CRISTIAN SUCIU, GEORGE ARGHIR, IOAN PETEAN and
CLAUDIU POPA, Heat treatment influence on sintered
manganese steels under abrasive wear (English, Romanian
summary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LIVIU BĂLAN, ANA TUFESCU, CARMEN BUJOREANU,
DUMITRU OLARU and SPIRIDON CREŢU, Evaluation of
the local gear scuffing (English, Romanian summary) . . . . . . . . 129
IULIANA ROTARU and DUMITRU OLARU, Lubrication regimes
in total disc prostheses on lumbar spine (English, Romanian
summary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
81
91
101
117
123

IULIANA ROTARU and DUMITRU OLARU, Pressure and
friction in total disc prosthesis: effect of surface conformity
(English, Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . . 147
VLAD CÂRLESCU, FLORIN BREABĂN (France), DUMITRU
OLARU and GHEORGHE PRISĂCARU, Experimental
methods for measuring the field-induced strain response of
dielectric elastomers (English, Romanian summary) . . . . . . . . 157
MIHAI BAICEANU, PAULO FLORES (Portugal), CEZAR
OPRISAN and DUMITRU OLARU, Effects of the driving
speed on the dynamic response of a four-bar mechanism with
clearance joints (English, Romanian summary) . . . . . . . . . . . . .
CARMEN BUJOREANU, BARBU DRĂGAN and VASILE
HORGA, Vibration control approach in low slip speed dry
friction systems (English, Romanian summary) . . . . . . . . . . . . . 173
CRISTEL ŞTIRBU, Tubing and casing connections. Functioning
aspects according to threads design problems (English,
Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
165
VIOREL PALEU and LIVIU BALAN, Power loss and temperature
computation in high-speed ball bearings lubricated by oil mist, I
Theoretical model (English, Romanian summary) . . . . . . . . . .
ALINA CORINA DUMITRASCU, GELU IANUS and DUMITRU
OLARU, Friction coefficient in the pivoting motion for a ballrace
contact (English, Romanian summary) . . . . . . . . . . . . . . . .
ALEXANDRU BUDEL, DUMITRU OLARU and GHEORGHE
PRISACARU, Ball kinematics in a linear recirculating system
with four contact points - analytical model (English, Romanian
summary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IRINA MARDARE and IRINA TITA, Aspects concerning
hydraulic systems with hydro pneumatic accumulators (English,
Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . .
ELENA RALUCA BACIU, IRINA GRĂDINARU, MARIA
BACIU and NORINA CONSUELA FORNA, Researches on
microstructure and micro hardness of titanium-based alloys
used in dental prosthetics (English, Romanian summary) . . . . .
CĂTĂLINA AXINTE, CORNELIU MUNTEANU and
ALEXANDRU BARNEA, Molybdenum coatings friction
coefficient studies for future applications in machine elements
191
201
207
215
219

(English, Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . .
CĂTĂLINA AXINTE, PETRU AVRAM, EDUARD SEBASTIAN
BÂRCĂ, BOGDAN ISTRATE and CORNELIU MUNTEANU,
Comparative studies of corrosion resistance on 21TMC12 steels
uncoated and coated with WC-Co-Cr (English, Romanian
summary) . . . . . . . . . . . . . . . . . . . . . . . . . .
ALEXANDRU BÂRCĂ, CĂTĂLINA AXINTE, PETRU AVRAM,
SORIN CLAUDIU IACOB STRUGARU and CORNELIU
MUNTEANU, Friction properties of WC coatings used in
automotive industry (English, Romanian summary) . . .
EDUARD SEBASTIAN BÂRCĂ, CĂTĂLINA AXINTE,
CONSTANTIN PAULIN, SORIN CLAUDIU IACOB
STRUGARU and CORNELIU MUNTEANU, Experimental
research on WC-Co-Cr coatings used in automotive industry
(English, Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . .
LUCIA ANIŞOARA DRĂGAN (RĂILEANU), CORNELIU
MUNTEANU, DANIEL MARECI, PINTILEI GEANINA
LAURA, ROMEU CHELARIU and CĂTĂLINA AXINTE,
Electrochemical studies of corrosion behaviour of experimental
TiNbZrAl alloys in artificial saliva (English, Romanian
summary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SORIN CLAUDIU IACOB STRUGARU, CORNELIU
MUNTEANU and CĂTĂLINA AXINTE, Corrosion
performances of Mo coatings deposited on steel substrates
(English, Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . .
CARMEN PĂPĂTOIU (BINIUC), CĂTĂLINA AXINTE,
EDUARD SEBASTIAN BÂRCĂ, SORIN CLAUDIU IACOB
STRUGARU and CORNELIU MUNTEANU, Properties of Mo
coatings obtained by thermal deposition on steel substrate
(English, Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . .
GEANINA LAURA PINTILEI, GICA NARCIS BASESCU,
TUDOR BRIAN LANDKAMMER, LAURA TEODORA
SOLONARIU, LUCIA ANISOARA DRAGAN and
CORNELIU MUNTEANU, Effect of heat-treatment of
atmospheric plasma spraying coating APS with powder ceramic
(English, Romanian summary) . . . . . . . . . . . . . . . . . . .
GEANINA LAURA PINTILEI,CORNELIU MUNTEANU, GICA
NARCIS BASESCU, TUDOR BRIAN LANDKAMMER,
BOGDAN ISTRATE and IONUT VASILE CRISMARU,
Stress analysis in the vicinity of the Vickers indentation by
227
233
239
245
253
263
269
277

finite element method (English, Romanian summary) . . . . . . . . 289
TUDOR BRIAN LANDKAMMER and LAURA TEODORA
SOLONARIU, Consideration regarding grain growth and
nucleation on solidified layers deposited by thermal spraying
(English, Romanian summary) . . . . . . . . . . . . . . . . . . . . . . . . . .
299
ANALYTIC DESCRIPTION OF TEETH PROFILE FOR
PRECESSIONAL MULTIPLIER
by
ION BOSTAN, VALERIU DULGHERU, RADU CIOBANU
Abstract: Absolute multiplicity of precessional gear (up to
100% pairs of teeth simultaneously involved in gearing, compared
to 5%-7% - in classical gearings) provides increased lifting
capacity and small mass and dimensions. To mention that until now
precessional planetary transmissions have been researched and
applied mainly in reducers. The mathematic model of the modified
teeth profile for precessional multipliers is presented in this work.
Key words: precessional transmission, gearing, teeth profile.
CORRELATION BEWEEN NANOMECHANICAL AND
TRIBOLOGICAL PROPERTIES OF HEALTHY AND
PATHOLOGICAL SYNOVIAL FLUIDS RECONSTITUTED
FROM SYNOVIOCYTE CULTURES
by
BOGDAN MUNTEANU, ANA-MARIA TRUNFIO SFARGHIU,
CONSTANTIN IONUT MATEI, SAW-SEE HONG, PIERRE
BOULANGER, MARIE-GENEVIEVE BLANCHIN, JEAN-PAUL
RIEU and YVES BERTHIER
Abstract. The aim of this study was to analyze the evolution of
the nano-mechanical and tribological properties of the synovial
fluids in joint diseases, in order to be able to correct their possible
mechanical causes. Thus, synovial fluids reconstituted in cell
cultures were studied by coupling: - AFM analysis, in order to
characterize the liposomal structures and the nano-mechanical

esistance of molecular assemblies which are present in these
fluids, and - Tribological analysis, to understand the evolution
during the friction of molecular structures in healthy and
pathological case. We analysed two types of reconstituted synovial
fluid, issued from (1) non- treated synoviocytes (healthy) and (2)
cultures of cytokine-treated synoviocytes, mimicking the joint
inflammatory environment. The molecular structures from the
reconstituted synovial fluids were nanomechanically analysed
using a commercial AFM. The tribological analyses were
performed using a home-made bio-tribometer that allows the
simultaneous measurement of frictional forces and fluorescence
observation of the lipid assemblies in order to detect any
degradation during friction. In the case of the reconstituted
synovial fluids from non-cytokine treated synoviocytes, the results
showed the presence of numerous lipid vesicles that grew in
diameter, from 30-70 nm to 1-2 µm, with an average Young
modulus of 3.37 MPa and adhesion force of 0 nN. The friction
coefficient was constant (~0.1) and no degradation of the lipid
bilayers was observed. In the case of pathological synovial fluids
reconstituted in vitro with their inflammatory environment, we
observed a progressive destruction of the vesicles and the
apparition of a gelatinous mass constituted by a glycoprotein gel
with an average Young modulus of 0.13 MPa and a high adhesion
force (1.51 nN). The friction coefficient increased until 0.45 with
an important degradation of the lipid bilayers. This study showed
that the presence of the lipid vesicles maintains a low and stable
friction coefficient in healthy cases, while their destruction
increases the friction coefficient in pathological cases.
Key words: lubrication, in vitro synovial fluid, lipid vesicle,
lipid bilayer, nanomechanical analysis, tribological analysis.
POWER LOSS AND TEMPERATURE COMPUTATION IN
HIGH-SPEED BALL BEARINGS LUBRICATED BY OIL MIST
II. THEORETICAL AND EXPERIMENTAL RESULTS
by
VIOREL PALEU
Abstract. The Part I of the paper presents a model for the
computation of the friction torque, power loss, and heat transfer in
ball bearings lubricated by oil mist. In this part, a test rig for

friction torque measurement is presented. For different ranges of
temperatures, axial preloads and speed, all steel-bearings from
7206C series are tested. The friction torque at the outer race level
is appreciated experimentally, the temperature of the bearings
housing being estimated by a laser tip Raynger MX4 device.
Regarding the friction torque in bearings, the theoretical results are
validated by experimental results, a good agreement being found.
To model the results on the evolution of the friction torque at
higher temperatures and higher speed, there is the need to
introduce starvation and thermal effects on lubricant film
thickness. The friction between the asperities of balls and races can
not be neglected in the model, this superposing the friction forces
due to the shearing of the oil film in contacts.
Key words: high-speed, ball bearings, oil-mist, temperature,
test rig, friction torque, power losses
PROFILE EVOLUTION IN CYLINDRICAL ROLLER
BEARINGS
I. ELASTIC-PLASTIC ANALYSIS
by
MARCELIN BENCHEA and SPIRIDON CRETU
Abstract. The class I discontinuities that exist along
cylindrical-crowned roller profile generate high pressure peaks in
pressure distributions that diminish considerably the modified
rating life as is defined by ISO 16281-2008. On the other hand, if
produced, these peaks might be able to generate both plastic
deformations and residual stresses. After a certain number of
cycles the material may shakedown elastically to a slightly
modified roller profile and a stable state of compressive residual
stresses. An analysis model has been developed to simulate the
nonlinear strain rate dependent deformation of rolling bearing steel
stressed in the elastic-plastic domain. Severe working conditions
(C/P > 0.3) as well as high transient overload are able to change
the roller profile to obtain a stress distribution in the contact zones
that provides enhanced operational reliability and greater
insensitivity to misalignment. If were taken place, these changes
have to be considered in the life evaluation.
Key words: elastic-plastic contact, non-linear hardening, plastic
deformation, cylindrical roller bearings.

MECHANICAL AND PHYSICOCHEMICAL PROPERTIES
OF THE DEEP DENTIN SURFACES
by
IRINA PELIN, ANA-MARIA TRUNFIO SFARGHIU,
PIERRE FARGE, AGNES PIEDNOIR, CHRISTOPHE PIRAT,
STELLA RAMOS
Abstract. The purpose of this study was to investigate the
mechanical and physicochemical properties of the etched and nonetched
deep dentin surfaces. The mechanical properties were
investigated by atomic force spectroscopy, and the
physicochemical properties by scanning electron microscopy
coupled with energy-dispersive X-ray spectroscopy and contact
angle measurements. The results showed that the apparent elastic
modulus decreases with the decrease of the mineral – organic ratio.
The information concerning the properties of dentin surfaces are
important for predicting the consequences of the microstructural
damages of the dentin caused by caries, some diseases or aging,
and of some restorative materials or dental procedures. Also, this
information is meaningful to the modelling of the dental obturation
process and to the estimation of the toughness and the efficacy of
the restorative materials.
Key words: apparent Young’s modulus, surface energy,
mineral – organic ratio
MODELLING THE KNEE JOINT MECHANICAL BEHAVIOUR
USING A 3D MODEL. A NUMERICAL SIMULATION
SOLUTION
by
ANA-MARIA AMANCEA, BENYEBKA BOU-SAЇD, CRISTEL
ŞTIRBU, MIHAI GAFIŢANU , MICHÈLE GUINGAND ,
CHRISTOPHE BARD
Abstract. The methodology of 3D knee model developing used
for analysis the mechanical behaviour of the knee is presented. The
model is created with a combination of software’s
(Catia/SimDesigner) that offers the possibility to obtain, in the
same time, data concerning the kinematic and dynamic aspects of

the knee. From kinematic points of view, the results presented in
current paper are validated according with Wilson’s experimental
results and the dynamical part of the model is validated with
(Moglo & Shirazi-Adl, 2003) and (Junior et al., 2009), results. The
presented model, that offers precious information about
mechanical behaviour of the joint, can be a base in the developing
of mechatronical systems used to assist or rehabilitate human knee
joint.
Key words: modelling, knee joint, rehabilitation, kinematic,
dynamic, mechatronics.
WEAR EVOLUTION IN CIRCULAR CONTACTS IN PARTIAL
SLIP
by
GEORGE GAVRILĂ and SPIRIDON CREŢU
Abstract. The paper presents a numerical model to investigate
fretting under partial slip conditions. An elastic contact model is
presented in order to solve both the normal and tangential contact
problem. The numerical approach to simulate wear is based on a
version of Archard wear law and is applied to a sphere on flat
geometry. Surface wear damage is predicted to have a significant
effect on the normal and shear tractions distribution for the partial
slip regime. The contact model is validated with analytical
solutions for a sphere on flat geometry and as well with different
numerical solutions from literature.
Key words: wear, stick-slip, friction, contact mechanics.
ANALYSIS OF STRESS STATE DEVELOPED CONTACTING
ELEMENTS WITH NON-GAUSS ROUGH SURFACES
by
ANA TUFESCU and SPIRIDON CREŢU
Abstract. The normal pressure distribution can be used to
predict subsurface stress, interfacial friction and surface wear.
Only few real rough surfaces are Gaussian, most of that produced
by manufacturing processes are non-Gaussian having an arbitrarily
orientation. The paper reveals the role played by the spatial

characteristics (standard deviation σ, skewness Sk, and kurtosis K)
as well as by autocorrelation function on both the non-Hertzian
pressure distribution on contact area and depth distribution of von
Mises equivalent stress.
Key words: concentrated contact, roughness, autocorrelation
length, von-Mises stress.
FATIGUE LIFE ANALYSIS ON ROLLER BEARINGS
WITH VARIOUS ROUGHNESS OF THE ACTIVE SURFACES
by
MIHAELA RODICA BĂLAN and SPIRIDON CREŢU
Abstract. The paper proposes a distinctive analysis of fatigue
life distribution in terms of roughness value on the inner ring or
roller using experimental results of the rolling contact fatigue tests
on cylindrical roller bearings. Thus, the following observations
were pointed out: an increase of the inner ring roughness causes a
significant decrease in fatigue life, for all roller roughness values,
and the roller roughness determine maximum fatigue life for
certain values. The correlation between fatigue life and roughness
was also studied by using the lubrication parameter Λ.
Key words: fatigue life test, roller bearing, surface roughness.
ON THE ROLE PLAYED BY ROUGHNESS PARAMETERS
ON PRESSURE AND STRESS DISTRIBUTIONS
IN WHEEL-RAIL CONTACT
by
CONSTANTIN BĂRBÎNŢĂ, ANA URZICĂ and SPIRIDON CREŢU
Abstract. The wheel and rail have rough contacting surfaces
and the pressures at such contacts far exceed the pressures that
would arise from a smooth contact. The freshly ground surface
roughness consists of peaks which in the first train-passes are
obliterated and become part of the interfacial layer. In this respect
the roughness of wheel and rail have been measured at different
working times, corresponding to successive stages of the running
in process. The measured roughness parameters have been further
used to generate stochastic roughness with imposed heights and

spatial parameters. Further, the rail and wheel surfaces with
numerically generated roughness have been incorporated into an
elastic-perfect plastic non-Hertzian contact model. The role played
by the running in process and main roughness parameters on both,
the pressure distribution on contact area and depth distribution of
von Mises equivalent stress, has been pointed out. Even the
nominal contact pressure was not able to cause von Mises stresses
greater than the yielding limit, the presence of surface roughness
brought on very large local asperity pressures that induced von
Mises stresses larger than yielding limit and accordingly possibly
severe plastic deformations inside a superficial layer of few tens of
microns thickness.
Key words: wheel-rail contact, roughness, skewness, kurtosis,
wear, von-Mises stress.
ROUGHNESS PARAMETERS
OF SURFACES OBTAINED BY ABRASIVE JET MACHINING
by
LAURENŢIU SLĂTINEANU, OANA DODUN, LORELEI
GHERMAN, IRINA GRIGORAŞ (BEŞLIU) and VASILE BRAHA
Abstract. Nowadays, there are various parameters which can be
used in order to evaluate the surface roughness. The sizes of such
parameters were measured in the case of some surfaces obtained
by abrasive jet machining. An experimental research was designed
and developed by considering a complete factorial experiment, in
which the independent variables were the average dimension of the
abrasive particles, the distance between the nozzle and the test
piece surface, the angle between the direction of the abrasive jet
and the surface of the test piece. Supposing a monotone variation
of the surface roughness parameters to the variation of the
independent variables, power type empirical functions were
established. The size of the exponents offers a more direct image
concerning the intensity of the influence exerted by the
independent factors on the sizes of the surface roughness
parameters.
Key words: abrasive jet machining, surface roughness
parameters, power type empirical functions, influence factors

RESIDUAL STRESSES REDUCTION USING CAE ANALYSIS IN
MOLDED POLYMERIC PARTS
by
ALEXANDRA RAICU
Abstract. To optimize polymeric parts and injection molding
conditions, it is important to predict the internal stress development
during molding and after ejection. The author intends to improve
the quality of the injection process and determinate the residual
stresses with respect to the temperature melt using CAE analysis.
In this paper in order to find the best parameters of the molding
process which lead to a minimum level of the residual stresses
several studies were performed. Parts made of polymeric materials
may be also simulated in order to minimize the residual stresses.
Computer Aided Engineering analysis provides insights useful in
designing parts, molds and molding processes. Using this method
we can obtain information such as polymer melt filling patterns,
weld line and air trap locations, required injection pressure and
clamp tonnage, fibre orientation, cycle time, the final part shape
and deformation and mechanical properties of molded parts. This
is a useful method to approach most of the molding problems.
Key words: polymeric part, CAE, residual stress.
EFFECT OF SINTERING TEMPERATURE ON HIGH
ALLOYING MANGANESE STEELS SUBJECTED TO ABRASIVE
WEAR
by
CRISTIAN SUCIU, GEORGE ARGHIR, IOAN PETEAN and
CLAUDIU POPA
Abstract. The influence of sintering temperature on the wear
rate of compacted Fe-Mn steel PM alloy was studied. Several
cylindrical specimens of iron powder (DWP400) and
ferromanganese powder (FeMn80C20) were made. Manganese
addition was of 5, 7, 9, 11, 13, 15 mass % and, for carbon was
0.14, 0.20, 0.26, 0.32, 0.38, 0.43 mass %, respectively. The
samples were pressed bilaterally at 600 MPa and, then, sintered in
H 2 at temperatures of 1120 °C and 1230 °C. These sintered
specimens were analyzed by optical microscopy and hardness

tests. After that, these samples were submitted to abrasive wear.
We have found that specimens sintered at high temperatures
present better abrasive wear behaviour. A linear increase of
hardness and, also, a linear decrease of wear rate, in dependence of
manganese addition were observed during these tests.
Key words: sintered steels, abrasive wear, manganese,
microstructure.
HEAT TREATMENT INFLUENCE ON SINTERED
MANGANESE STEELS UNDER ABRASIVE WEAR
by
CRISTIAN SUCIU, GEORGE ARGHIR, IOAN PETEAN and
CLAUDIU POPA
Abstract. It was observed that the heat treatment has a great
influence on sintered manganese steels behaviour. The proposed
paper is focused on analysis of abrasive wear of sintered specimens
subjected to heat treatment (quenching and tempering) of 960 °C
for 60 minutes and 180 °C for 40 minutes, respectively. The
analyzed samples were a mixture of iron powder allied with 5, 7, 9,
11, 13, 15 mass % Man. Heat treated specimens have been
subjected to investigations by optical microscopy and hardness
tests. It was found a decrease in hardness, with increasing of
manganese content, after tests. Also, abrasive wear is strongly
influenced by the hardness of the specimens.
Key words: heat treatment, abrasive wear, sintering,
manganese, microstructure
EVALUATION OF THE LOCAL GEAR SCUFFING
by
LIVIU BALAN, ANA TUFESCU, CARMEN BUJOREANU,
DUMITRU OLARU AND SPIRIDON CRETU
Abstract. The authors determined the local scuffing criterion
for rolling/sliding contacts by considering both the roughness on
surfaces and lubricant film. The real pressure distributed in
rolling/sliding contact operating in mixed lubrication conditions
has been determined. Also the tangential shear stress correlated
with the lubricant parameter λ was obtained and finally the local

scuffing criterion SL was calculated for given rollers geometry and
operating conditions.
Key words: rolling/sliding contacts, scuffing criteria, real
pressure, lubricant parameter.
LUBRICATION REGIMES IN TOTAL DISC PROSTESES ON
LUMBAR SPINE
by
IULIANA ROTARU and DUMITRU OLARU
Abstract. Total disc prostheses are medical devices used for
treatment of disc herniation. These are more attractive than spinal
fusion procedure because they restore and maintain spinal segment
motion. The objective of this paper was to determine the maps of
lubrication regimes which occur in total disc prostheses on lumbar
spine. The prostheses were modelled as ball-and-socket designs. It
was considered a ball radius of 14 mm with radial clearances
between ball and socket of 0.01 and 0.1 mm, a lubricant with a
viscosity of 1.24 mPa s and an angular velocity of 1.75 rad/s. The
results have indicated that the lubrication regimes in total disc
arthroplasty were isoviscous-elastic (IVR) and isoviscous-rigid
(IVR) only for a radial clearance of 0.01 mm when normal force
was lower than 55 N in case of metal-on-metal devices, lower than
15 N in case of metal-on-plastic and lower than 65 N in case of
ceramic-on-ceramic.
Key words: lubrication regime, lubricant, lumbar spine, total
disc prosthesis.
PRESSURE AND FRICTION IN TOTAL DISC PROSTHESIS:
EFFECT OF SURFACE CONFORMITY
by
IULIANA ROTARU and DUMITRU OLARU
Abstract. Total disc prosthesis is an artificial disc used to
replace the damaged intervertebral disc. There are different designs
of artificial discs, but one of the most general is ball-and-socket
model. The objective of this study was to investigate the influence
of surface conformity on the maximum pressure and the frictional

torque which occur in lumbar total disc prostheses. It was
considered a ball radius of 14 mm and socket radii between 14.01
and 14.1 mm. The maximum pressure and the frictional torque
were then determined for different material combinations and
conformities. This study suggests designing of total disc prostheses
with high conformity of the sliding surfaces in order to reduce
maximum pressure and with ceramic-on-ceramic material
combination in order to reduce frictional torque.
Key words: ball-and-socket, friction, radius, pressure, surface
conformity, total disc prosthesis.
EXPERIMENTAL METHODS FOR MEASURING THE FIELD-
INDUCED STRAIN RESPONSE OF DIELECTRIC
ELASTOMERS
by
VLAD CÂRLESCU, FLORIN BREABĂN, DUMITRU OLARU,
GHEORGHE PRISĂCARU
Abstract. In last years, there is a growing demand in fields such
as mechatronics, medicine and bioengineering, for polymer
actuators. Electroactive polymers (EAP) are polymers that exhibit
shape change in response to electrical stimulation. In order to
develop good actuator and sensor applications based on EAPs we
need to investigate the mechanical, electrical and
electromechanical properties of EAP materials. This paper present
two non-destructive testing methods used for measuring the fieldinduced
strain response of dielectric elastomers. We performed
static and dynamic experiments to investigate the strain response
induced by DC and AC electric fields.
Key words: electroactive polymers, strain response,
displacement sensor method, laser scanning Doppler vibrometry,
accuracy.
EFFECTS OF THE DRIVING SPEED ON THE DYNAMIC
RESPONSE OF A FOUR-BAR MECHANISM WITH
CLEARANCE JOINTS
by
MIHAI BAICEANU, PAULO FLORES, CEZAR OPRISAN and

DUMITRU OLARU
Abstract. The main purpose of this work is to present the
effects of the input speed on the dynamic characteristics of a fourbar
mechanism with clearance joint between coupler and follower.
It can be observed that, increasing the input speed of the
mechanism makes the behaviour of the mechanical system to
change from periodic to chaotic. The numerical results show that
the existence of dry joint clearance causes high peaks on the
dynamic system’s characteristics due to contact forces developed.
Key words: joint clearance, dynamic response, input speed,
revolute joint, four-bar mechanism, contact force model
VIBRATION CONTROL APPROACH IN LOW SLIP SPEED
DRY FRICTION SYSTEMS
by
CARMEN BUJOREANU, BARBU DRĂGAN and VASILE HORGA
Abstract. Structures and mechanical systems should be
designed to enable better performance under different types of
loading, particularly dynamic and transient loads. The instability of
a dynamic system where there is an interaction between the elastic
system and the friction process behaves as a stick-slip movement
of the contact masses For example, it is known that in dry friction
conditions, the printing speed causes a problem called "stick-slip"
and the dye ribbon is not peeled smoothly away from the receiving
sheet in the printer. This results in noise and leaves scratch marks
on the printed image. Arising of the stick-slip phenomenon is
conditioned by the slip movement and vibrations generation. The
paper presents some observations related to the control of these
vibrations
Key words: nonlinear friction, vibration control.
TUBING AND CASING CONNECTIONS.
FUNCTIONNING ASPECTS ACCORDING TO THREADS
DESIGN PROBLEMS
by
CRISTEL ŞTIRBU

Abstract. Different joints for extractive industry have a lot of
similar theoretical, technological and dimensional aspects:
dimensional correlation with the pipes, drill and other well
elements; mechanical strength of pipes and joints to the inner and
outer pressure and to the proper weight of the column; bending
resistance of the column under different conditions of the ground
properties; resistance under high temperatures of the column;
perfect seal functioning, for extraction efficiency; resistance to
corrosive conditions; resistance to the mechanical wear and the
possibility of the reutilization of the component elements. The
main element of tubing and casing connection is the thread which
ensures all the performances of the well column. The paper shows
some considerations on the thread influence on different
connection types.
Key words: connection, pipes, thread, seal.
POWER LOSS AND TEMPERATURE COMPUTATION IN
HIGH-SPEED BALL BEARINGS LUBRICATED BY OIL MIST
I. THEORETICAL MODEL
by
VIOREL PALEU and LIVIU BALAN
Abstract. The paper presents a model for friction torque, power
losses, and heat transfer in ball bearings lubricated by oil mist.
This improves the existing models, the friction torque and power
losses being estimated more accurately with the Houpert method,
further extended by Paleu for the oil mist lubrication of high-speed
angular ball bearings. Theoretical results are presented for a 7206C
angular contact ball bearings. The lubrication regime is identified
in balls and races contacts, as it influences the lubrication
parameter and ratio of load supported by asperities and fluid film
contact area. The transition from IVR to EHD lubrication regime is
emphasised by the evolution of the oil film thickness versus the
axial preload. The model is validated with experimental results
regarding the mean temperature of the 7206C bearings, found in
literature. This research can be easily extrapolated on gears.
Key words: high-speed, ball bearings, oil-mist, temperature,
lubrication regimes.

FRICTION COEFFICIENT IN THE
PIVOTING MOTION FOR A BALL-RACE CONTACT
by
ALINA CORINA DUMITRASCU, GELU IANUS and DUMITRU
OLARU
Abstract. This paper presents the methodology and results to
determine the friction coefficient in the pivoting motion for a
microball with diameter of 1.588 mm on race of a thrust ball
bearing .Experiments were performed in dry conditions at a
temperature of 20 0 C, and humidity between 45-55% RH at loads
of 8.68 mN, 15 mN, 22.3 mN, 27 mN and 33.2 mN. Values of the
friction coefficient in the pivoting motion between 0.1 and 0.2
were obtained.
Key words: friction coefficient, pivoting motion, experimental
procedure
BALL KINEMATICS IN A LINEAR RECIRCULATING SYSTEM
WITH FOUR CONTACT POINTS - ANALYTICAL MODEL
by
ALEXANDRU BUDEL, DUMITRU OLARU and GHEORGHE
PRISACARU
Abstract. An original procedure to determine both the value of
the ball angular speed and the angular position of this speed,
according to the normal loads in a linear system with four contact
points has been developed. The program is based on the variational
analysis of the power losses in ball-races contacts. Based on this
program was determined the two kinematics parameters of the ball
(angular velocity and angular position) in a linear system type
KUE 35V2 as function of the ratio C/P.
Key words: Linear guidance system, ball angular speed,
angular position, normal loads.
ASPECTS CONCERNING HYDRAULIC SYSTEMS WITH
HYDROPNEUMATIC ACCUMULATORS
by
IRINA MARDARE and IRINA TITA

Abstract. In this paper some aspects regarding hydropneumatic
accumulators are investigated. Fundamental equations governing
the functioning of hydropneumatic accumulators are presented and
also aspects regarding details to be considered in governing
equations are analyzed. A functional diagram, based on MATLAB
/ SimHydraulics computational approach suited to analyze the real
physical system consisting of real physical functional blocks, is
developed for modelling and simulating a system with a
hidropneumatic accumulator.
Key words: hydraulic system, hydropneumatic
accumulator, functional diagram, MATLAB.
RESEARCHES ON MICROSTRUCTURE AND
MICROHARDNESS OF TITANIUM-BASED ALLOYS USED IN
DENTAL PROSTHETICS
by
ELENA RALUCA BACIU, IRINA GRĂDINARU, MARIA BACIU,
NORINA CONSUELA FORNA
Abstract. Microstructural researches on Ti-based alloys under
analysis aimed at identifying the main structural constituents that
will influence their subsequent behaviour during the finishing
processes by mechanical polishing. The aluminum and niobium
alloy determined the modification of structural constitution in case
of Biotan Nb alloy, since the two solid solutions formed are
characterized by high values of microhardness, a fact that will lead
to a more difficult mechanical finishing.
Key words: Ti-based alloys, microstructure, microhardness.
MOLYBDENUM COATINGS FRICTION COEFFICIENT
STUDIES FOR FUTURE APPLICATIONS
IN MACHINE ELEMENTS
by
CĂTĂLINA AXINTE, CORNELIU MUNTEANU
and ALEXANDRU BARNEA
Abstract. Gears are machine elements which transmit high
torques by friction of the tooth and on the flanks appear the pitting

wear after many cycles of working. In operating are subjected are
subjected to mainly to fatigue. After a detailed study of the
literature we decided to modify the contact surface by coating. We
have chosen the steel type 16MnCr5 and we coated it with Mo.
When we obtained the samples, we subjected them to fretting tests
in order to determine the friction coefficient. On the roughness
analysis we obtained the quality of the coatings. The results
showed how behaved the surface after more than one million
cycles, and how the surface was influenced by friction.
Key words: coating, fretting, friction, etc.
COMPARATIVE STUDIES OF CORROSION RESISTANCE ON
21TMC12 STEELS UNCOATED AND COATED WITH WC-Co-Cr
by
CĂTĂLINA AXINTE, PETRU AVRAM, EDUARD SEBASTIAN
BÂRCĂ, BOGDAN ISTRATE and CORNELIU MUNTEANU
Abstract. Gears tooth are subjected to fatigue and bending but if
they are working in aggressive environments, they must have high
corrosion resistance. Our researches are concentrated on the surface
modification by plasma spraying coating process. We researched the
specialty literature and we decided to use usual steel, 21TMC12,
which we coated it with powder, WC-Co-Cr by plasma spraying
process. When we obtained the samples, we subjected them to
hardness and corrosion test and then we analyzed them by electronic
microscopy. The results showed that the coating has a higher
corrosion resistance than basic steel.
Key words: coating, electron microscopy, corrosion, etc.
FRICTION PROPERTIES OF WC COATINGS USED IN
AUTOMOTIVE INDUSTRY
by
ALEXANDRU BÂRCĂ, CĂTĂLINA AXINTE, PETRU AVRAM,
SORIN CLAUDIU IACOB STRUGARU and CORNELIU
MUNTEANU
Abstract. Engine cylinder bores are machine elements that are
subjected to friction solicitation. The geometry dimensions and

weight cannot be modifying that is why we decided to modify the
contact surface by coating. We have chosen the steel type OLC 45
and we coated it with WC by thermal deposition. The selection of
these materials has done after a detailed study of the literature. After
we obtained the samples, we subjected them to fretting analysis
where we obtained the friction force and friction coefficient
between two coated surfaces in dry contact. The results showed how
the coating influences the properties of the basic material.
Key words: coating, fretting, friction force, dry contact, etc.
EXPERIMENTAL RESEARCH ON WC-Co-Cr COATINGS USED
IN AUTOMOTIVE INDUSTRY
by
EDUARD SEBASTIAN BÂRCĂ, CĂTĂLINA AXINTE,
CONSTANTIN PAULIN, SORIN CLAUDIU IACOB STRUGARU,
and CORNELIU MUNTEANU
Abstract. The pistons of engines are machine elements which
are subjected to thermal and friction solicitations. The pistons must
have a high wear resistance that is why we proposed to improve
their performances. Their surfaces are complex and we decided to
modify them, because the contact between piston cylinders should
be improved. We have done researches in surface engineering and
obtained a solution by coating the basic material’s surface with a
better material. We used the WC-Co-Cr powder and by plasma
spraying deposition we made a coating on the steel type 21TMC12.
We analyzed the samples by SEM and X-Ray Diffraction to
determine the quality of the coating. The results showed that the
new material has better properties than the basic material.
Key words: coating, SEM, X-Ray Diffraction, etc.
ELECTROCHEMICAL STUDIES OF CORROSION BEHAVIOUR
OF EXPERIMENTAL TiNbZrAl ALLOYS
IN ARTIFICIAL SALIVA
by
LUCIA ANIŞOARA DRĂGAN (RĂILEANU), CORNELIU
MUNTEANU, DANIEL MARECI, PINTILEI GEANINA LAURA,
ROMEU CHELARIU, CĂTĂLINA AXINTE

Abstract. The aim of this study is to investigate the corrosion
behaviour of a two TiNbZrAl alloys (coded with Ti17Nb5Zr5Al and
Ti8Nb6Zr2Al) in artificial saliva. For comparison, Cp-Ti was also
investigated. In order to study the corrosion resistance the linear
potentiodynamic polarization and electrochemical impedance
spectroscopy (EIS) were performed. Scanning electron microscopy
(SEM) observations were made following the linear
potentiodynamic polarization tests. The EIS results for TiNbZrAl
alloys exhibited capacitive behaviour (high corrosion resistance)
with high impedance order (106 Ω cm 2 ) at low to medium
frequency.
Key words: TiNbZrAl alloys, corrosion current density, linear
potentiodynamic polarisation curves, SEM, EIS.
CORROSION PERFORMANCES OF Mo COATINGS
DEPOSITED ON STEEL SUBSTRATES
by
SORIN CLAUDIU IACOB STRUGARU, CORNELIU MUNTEANU
and CĂTĂLINA AXINTE
Abstract. Researches in surface engineering allow the obtaining
of new systems of materials by coating the basic material surface
with other material having superior properties. In our researches we
proposed to obtain a new system of materials by thermal deposition.
We have chosen the steel type 16MnCr5 as basic material and we
coated it with Mo. We have subjected the samples to hardness and
corrosion tests in order to estimate the material performances. The
results showed that the new material has a higher hardness and
corrosion resistance than the steel.
Key words: coating, hardness, corrosion, durability, etc.
PROPERTIES OF Mo COATINGS OBTAINED BY THERMAL
DEPOSITION ON STEEL SUBSTRATE
by
CARMEN PĂPĂTOIU (BINIUC), CĂTĂLINA AXINTE,
EDUARD SEBASTIAN BÂRCĂ, SORIN CLAUDIU IACOB
STRUGARU and CORNELIU MUNTEANU

Abstract. In aircraft industry are many machine elements which
are subjected to thermal and friction solicitation. These machine
elements must have a high wear resistance, because the passenger’s
safety is very important. Also the maintenance costs are very high,
that is why we proposed to improve the performances of the
machine elements. Researches in surface engineering allow the
obtaining of new systems of materials by coating the basic material
surface with other material having superior properties. In order to
improve the machine elements durability, we proposed to obtain a
new system of materials by thermal deposition. We have chosen the
steel type 16MnCr5 as basic material and we coated it with Mo. We
made the samples AND we have analyzed by X-Ray Diffraction
obtaining their quality. The results showed that the new material has
a better structure than the basic material.
Key words: coating, X-Ray Diffraction, thermal deposition.
EFFECT OF HEAT-TREATMENT OF ATMOSPHERIC PLASMA
SPRAYING COATING (APS) WITH POWDER CERAMIC
ZrO 2 /20% Y 2 O 3
by
GEANINA LAURA PINTILEI, GICĂ NARCIS BĂSESCU, TUDOR
BRIAN LANDKAMMER, LAURA TEODORA SOLONARIU, LUCIA
ANIŞOARA DRAGAN and CORNELIU MUNTEANU
Abstract. A significant issue in obtaining the thermal barrier
coating applied on the turbine blades is to determine the causes of
exfoliation of the ceramic layer due to the large number of thermal
cycles. This paper presents a new concept of thermal barrier coating
for the prevention of delamination of the sprayed layer. This
consists in an adherent layer of NiMoAl (90-5-5) sprayed with
electric arc and a top coat of ZrO 2 /20%Y 2 O 3, deposited by
atmospheric plasma spraying (APS) on specimens of Ni base
superalloy, of which the aircraft turbine blades are made. The
samples have been exposed to a heat treatment at 1150°C in order to
study the behaviour of the sprayed layers. Porosity was evaluated by
image analysis. This technique was used to estimate porosity
variation along the cross section. The use of a scanning electron
microscope had the role of observing the morphology and
microstructure, the distribution maps and chemical analysis. The

surface roughness was also determined before and after the
treatment.
Key words: SEM, profilometry, heat treatment, ZrO 2 /20%Y 2 O 3 .
STRESS ANALYSIS IN THE VICINITY OF THE VICKERS
INDENTATION BY FINITE ELEMENT METHOD
by
GEANINA LAURA PINTILEI, CORNELIU MUNTEANU, GICĂ
NARCIS BĂSESCU, TUDOR BRIAN LANDKAMMER, BOGDAN
ISTRATE and IONUŢ VASILE CRÎŞMARU
Abstract. In this paper it’s presented the experimental method
for determining the resistance to cracking of ceramics using Vickers
indentation.
The method used in this case is called the micro-fissures method
(MF) and it is result is the resistance to cracking in the vicinity area
of the mechanical stresses determined by the Vickers indentation.
The sample used for the test consists of an adherent layer of
NiMoAl (90-5-5) sprayed with electric arc and a top coat of
ZrO 2 /20%Y 2 O 3, deposited by atmospheric plasma spraying (APS)
on samples of an Ni base superalloy.
The highlighting and interpretation of the structural changes
caused by the tests which were carried out have been made using
modern methods of structural analysis: electron microscopy and
finite element analysis.
Key words: Vickers indentation, SEM, tensions, hardness.
CONSIDERATION REGARDING GRAIN GROWTH AND
NUCLEATION ON SOLIDIFIED LAYERS
DEPOSITED BY THERMAL SPRAYING
by
TUDOR BRIAN LANDKAMMER and LAURA TEODORA
SOLONARIU
Abstract. The solidification process includes nucleation and
growing steps, each of them are being influenced by specific
parameters. According to some specific condition, nucleation can be
homogeneous or heterogeneous and it will assure the forming

condition of an amorphous or crystalline microstructure.
Knowing the values of the technological parameters for
spraying it is possible to determine the growing speed of a sprayed
layer through mathematical calculation or by numerical simulation.
Keywords: thermal spraying, nucleation, crystal morphology,
technological parameters.