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Department of Machine and Industrial Product Design
Contact person: Dr. Tibor Goda (e-mail: goda.tibor@gt3.bme.hu)
Department of Machine and Industrial Product Design 2
GM research topics relating to this area : 8, 10, 65
LUBRICATION AND FRICTION PREDICTION
Competence in:
1. Modeling of adhesion
2. Boundary lubrication(shear strength of the boundary layer)
3. Numerical modelingof fluid and mixedfriction
Geometrical sizes of the seal and the rodMaterial properties of the rubber seal (E,n)Sealed pressure (psealed)Rod speed (outstroke+instroke)Fluid viscosity at atmospheric pressure (m0)Pressure viscosity coefficient (a)Combined surface roughness of the rod andthe seal (s,R,h)Coefficient of friction at asperity contact (f)Length of the sealing zone (L)Number and coordinates of contact nodesStatic contact pressure at the contact nodes(psc)Influence coefficient matrix for the contactnodes (Iij)Static film thickness at the contact nodes (Hs)
Initial guess for the film thickness
(distance between mean surfaces at the given node)
Contact analysis
(Greenwood-Williamson
contact model)
Calculation of the flow
factors
Calculation of the truncated film thickness (hT)
Discretized Reynolds equation (linear algebraic
equations) non-linearity induced by pressure dependent viscosity
Calculation of the total pressure (pt=pfluid+pcontact)
Calculation of seal deformation induced by hydrodynamic and contact
pressure
Calculation of leakage and friction force
Contact pressure due to asperity contact (pcontact)
Fluid pressure (pfluid)Location of the full film and the cavitated regions
Updated film thickness
N
1kksctiksi ppIHH
N
1kksctik ppI
LUBRICATION AND FRICTION PREDICTION
Present research activity of the department in this field:
EU FP6 research project „Knowledge-based Radical Innovation Surfacing for Tribology and Advanced Lubrication” (EU Project Reference NMP3-CT-2005-515837, www.kristal-project.org)
References:[1] Kozma, M.: „Hydrodynamic and boundary lubrication of elastomer seals”, 19th International Conference on Fluid Sealing, Poitiers, France[2] Goda T. J.: "Numerical modelling of lubrication in reciprocating hydraulic rod seals„, Proceedings of sixth conference on mechanical engineering, ISBN 978-963-420-947-8, (2008)
4. Oil/grease lubricated sliding contact
5. Modeling of rheological behavior of lubricants
0
2
4
6
8
0 0.02 0.04 0.06 0.08 0.1
Sliding speed, m/s
Fric
tion
forc
e, N
h1 = 1um h1 = 0.5 um h1 = 0.2 um
measured h1 = 0.15 um
Diapragm seal, l=100 mm,
h 0.2 Pas, t bound = 0.43 MPa,
Rmax=2 mm
y = 862.87x-0.7963
y = -0.0003x2 + 1.9665x + 1956.8
0
1000
2000
3000
4000
5000
0 500 1000 1500 2000
Shear rate, 1/s
Sh
ea
r st
ress
, Pa
0
20
40
60
80
100
Vis
cosi
ty, P
as
Shear stress Viscosity
20°C
Grease Molykote PG 54
Department of Machine and Industrial Product Design 4
GM research topics relating to this area : 31
RUBBER PHYSICS
Competence in:1. Modeling of the non-linear, time- and temperature-dependent material behavior of rubber and rubber-like materials
2. Characterization of the asphalt’s surface topography (Power Spectral Analysis, surface roughness measurements, etc.)
3. Contact modeling of rubber/ rough counterpart sliding pairs
3.57
-6.59
A PSD [μm4]qx, qy [μm-1]
-0.3log10qx
log10APSD
-0.3
log10qy
-3-3
3.90
-7.05
-0.3log10qx
log10APSD
-0.3
log10qy
-3-3
CONTACT MECHANICS, RUBBER FRICTION (SLIDING AND ROLLING), FE MODELLING
Department of Machine and Industrial Product Design 5
RUBBER PHYSICS
4. FE modeling of hysteresis induced rolling and sliding resistance5. FE modeling of hysteresis induced and friction related heat generation (thermo-mechanical coupled analysis) Present research activity of the department in this field:
EU FP6 research project „Knowledge-based Radical Innovation Surfacing for Tribology and Advanced Lubrication” (EU Project Reference NMP3-CT-2005-515837, www.kristal-project.org)
References:[1] Goda, T.; Pálfi, L.; Váradi, K.; Garbayo, E.; Bielsa, J.M.: “FE prediction of the hysteretic component of rubber friction: importance of the Maxwell-parameters”, Fall Rubber Colloquium, (2008), pp. 128[2] Felhős, D.; Xu, D.; Schlarb, A.K.; Váradi, K.; Goda, T.:”Viscoelastic characterization of an EPDM rubber and finite element simulation of its dry rolling friction”, EXPRESS POLYMER LETTERS, Vol. 2, No.3, (2008) pp.157-164
CONTACT MECHANICS, RUBBER FRICTION (SLIDING AND ROLLING), FE MODELLING
Department of Machine and Industrial Product Design 6
GM research topics relating to this area : 67
FE THERMAL MODELLING
Competence in:1. Transient and steady-state FE thermal modeling (heat partition, thermal contact resistance, contact conductive heat flux, etc.)
2. Stick-slip related thermal problems
3. Coupled thermo-mechanical analysis
27
195
Temperature [°C]
Z
X27
195
Temperature [°C]
Z
X
#1
#2
POINT A POINT B
#1#2
194
110
27
195
110
27
T °C T °C
I/a
I/b
II/a
II/b
Z
X
ZX
Department of Machine and Industrial Product Design 7
FE THERMAL MODELLING
4. Moving and distributed heat source models
Present research activity of the department in this field:Hungarian National Scientific Research Foundation project: „Friction behaviour and failure mechanisms of polymer, elastomer, ceramic and composite structural components”, OTKA (NI 62729)
References[1] Lestyán, Z.; Váradi, K.; Albers, A.: „Contact and thermal analysis of an alumina-steel dry sliding friction pair considering the surface roughness”, TRIBOLOGY INTERNATIONAL, Vol. 40, pp. 982-994 (2007)[2] Fekete, G.; Váradi, K.; Leali, M.; Bottarelli, F.: "Thermal FE analysis of a pneumatic cylinder„, Proceedings of sixth conference on mechanical engineering, ISBN 978-963-420-947-8, (2008)
Department of Machine and Industrial Product Design 8
GM research topics relating to this area : 101
WEAR DETECTION AND SIMULATION
Competence in:1. FE wear simulation
FE contact calculation (instroke)
Wear calculation
Moving the nodes
Nodal Contact Normal Stress
Nodal wear depth
New geometry
End
Initial geometry
Specific wear rate
FE contact calculation (outstroke)
Wear calculation
Moving the nodes
Nodal Contact Normal Stress
Nodal wear depth
New geometry
Start
Department of Machine and Industrial Product Design 9
WEAR DETECTION AND SIMULATION
Present research activity of the department in this field:
Hungarian National Scientific Research Foundation project: „Friction behaviour and failure mechanisms of polymer, elastomer, ceramic and composite structural components”, OTKA (NI 62729)
References:[1] Kónya, L.; Váradi, K.: „Wear simulation of a polymer-steel sliding pair considering temperature- and time-dependent material properties”, in Friedrich, K.; Schlarb, A.K. (editors) „Tribology of Polymeric Nanocomposites”, TRIBOLOGY AND INTERFACE ENGINEERING SERIES, No. 55, Elsevier, (2008) ISBN 978-0-444-53155-1
2. Modeling and interpretation of typical wear mechanisms
3. Characterization of worn surfaces
x
z
y
3
3
[μm]
2.56
- 5.56
0
[mm]
[mm]