Department of Machine and Industrial Product Design Contact person: Dr. Tibor Goda (e-mail: [email protected])[email protected].

Department of Machine and Industrial Product Design

Contact person: Dr. Tibor Goda (e-mail: [email protected])

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]