micro molding

Wear simulation of tribosystems Dr. Vishwanath Hegadekatte University of Karlsruhe

Prof. Norbert Huber

GKSS Forschungszentrum Geestacht GmbH Hamburg University of Technology

Abaqus Germany User Conference 2007 Baden-Baden, Germany 18 Sept 2007 SFB 499 · Design, production and quality assurance of molded micro-components made from metals and ceramics Dr. V. Hegadekatte: Wear simulation of tribosystems 1

Contents

1.

Motivation and strategy

2. Numerical Tools: GIWM, WP, UM 3. Pin-on-disc tribometer 4. Twin-disc tribometer 5. Summary

Dr. V. Hegadekatte: Wear simulation of tribosystems

2

Motivation

SFB 499 Model System: Micro-planetary gear train

™ ™ ™ ™

Micromachines are finding a wide variety of applications High surface to volume ratio High operating speeds Wear is a critical factor which can limit their life span Dr. V. Hegadekatte: Wear simulation of tribosystems

3

GIWM (Global Incremental Wear Model) V. Hegadekatte et al., Tribology Letters, 2006, 24, 51 - 60.

FN ΔV = k Δs H = k D FN Δs Δh = k D pΔs FN p= 2 πai

Assumptions ™ Archard’s wear law FN u= ™ Average contact pressure over circular contact area 2 EC ai ™ Assumes axisymmetric wear on pin surface ™ Normal elastic displacement taken into account (Oliver & Pharr, 1992) ™ Linear wear integrated over sliding distance Dr. V. Hegadekatte: Wear simulation of tribosystems

4

Wear-Processor (WP) Wear Processor

FEM FEM (ABAQUS) (ABAQUS) Update Update Surface Surface Topography Topography (Re-meshing) (Re-meshing)

Compute Compute Wear Wear

V. Hegadekatte et al., Modelling Simul. Mater. Sci. Eng., 2005, 13, 57 - 75.

Dr. V. Hegadekatte: Wear simulation of tribosystems

5

Wear-Processor (WP) Wear Processor

FEM FEM (ABAQUS) (ABAQUS) Update Update Surface Surface Topography Topography (Re-meshing) (Re-meshing)

Compute Compute Wear Wear

V. Hegadekatte et al., Modelling Simul. Mater. Sci. Eng., 2005, 13, 57 - 75.

Dr. V. Hegadekatte: Wear simulation of tribosystems

Wear-Processor (WP) Wear Processor

FEM FEM (ABAQUS) (ABAQUS) Update Update Surface Surface Topography Topography (Re-meshing) (Re-meshing)

Compute Compute Wear Wear

V. Hegadekatte et al., Modelling Simul. Mater. Sci. Eng., 2005, 13, 57 - 75.

Dr. V. Hegadekatte: Wear simulation of tribosystems

Wear-Processor (WP) Pin Wear

Wear Processor

FEM FEM (ABAQUS) (ABAQUS) Update Update Surface Surface Topography Topography (Re-meshing) (Re-meshing)

Compute Compute Wear Wear

V. Hegadekatte et al., Modelling Simul. Mater. Sci. Eng., 2005, 13, 57 - 75.

Dr. V. Hegadekatte: Wear simulation of tribosystems

Wear-Processor (WP) Pin Wear

Wear Processor

FEM FEM (ABAQUS) (ABAQUS) Disc Wear Surface Update Update Surface Topography Topography (Re-meshing) (Re-meshing)

Compute Compute Wear Wear

V. Hegadekatte et al., Modelling Simul. Mater. Sci. Eng., 2005, 13, 57 - 75.

Dr. V. Hegadekatte: Wear simulation of tribosystems

Wear-Processor (WP) Pin Wear

Wear Processor

FEM FEM (ABAQUS) (ABAQUS) Disc Wear Surface Update Update Surface Topography Topography (Re-meshing) (Re-meshing)

Compute Compute Wear Wear

V. Hegadekatte et al., Modelling Simul. Mater. Sci. Eng., 2005, 13, 57 - 75.

Dr. V. Hegadekatte: Wear simulation of tribosystems

Wear-Processor (WP) Wear Processor

FEM FEM (ABAQUS) (ABAQUS) Update Update Surface Surface Topography Topography (Re-meshing) (Re-meshing)

Compute Compute Wear Wear

V. Hegadekatte et al., Modelling Simul. Mater. Sci. Eng., 2005, 13, 57 - 75.

Dr. V. Hegadekatte: Wear simulation of tribosystems

UMESHMOTION (UM)

Δh = k D pΔs

™ User-defined subroutine in ABAQUS ™ For defining motion of nodes in an Adaptive Meshing constraint node set ™ Eulerian analysis for sweeping the nodes ™ Material quantities are remapped using Lax-Wendroff method ™ Equilibrium is corrected by re-solving the last time increment

Dr. V. Hegadekatte: Wear simulation of tribosystems

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Pin-on-disc: GIWM V. Hegadekatte et al., Tribology Letters, 2006, 24, 51 - 60.

Prediction

Fit

Si3N4 in Air ™ GIWM can fit pin-on-disc experimental results ™ GIWM can also predict pin-on-disc experimental results when load is doubled Dr. V. Hegadekatte: Wear simulation of tribosystems

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WC-Co in Water

hexperiment

hGIWM

Wear Depth, h

Friction Coefficient, µ

GIWM: Water lubrication

Normal Load,

Dr. V. Hegadekatte: Wear simulation of tribosystems

14

Pin-on-disc: WP & GIWM

Si3N4 in Air

V. Hegadekatte et al., Tribology Letters, 2006, 24, 51 - 60.

Dr. V. Hegadekatte: Wear simulation of tribosystems

15

Twin-disc

Dr. V. Hegadekatte: Wear simulation of tribosystems

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Twin-disc

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: UMESHMOTION (UM) For one rotation, θ = 2π

hi +1 = hi + k D

prdθ ∫ θ =0

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: UMESHMOTION (UM) For one rotation, θ = 2π

hi +1 = hi + k D

prdθ ∫ θ =0

For a given time increment of Δti θ =2π

Δti | (V1 −V2 ) | hi+1 = hi + kD prdθ ∫ 2πr θ =0 Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: UMESHMOTION (UM) For one rotation, θ = 2π

hi +1 = hi + k D

prdθ ∫ θ =0

For a given time increment of Δti θ =2π

Δti | (V1 −V2 ) | hi+1 = hi + kD prdθ ∫ 2πr θ =0 Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: UMESHMOTION (UM) For one rotation, θ = 2π

hi +1 = hi + k D

prdθ ∫ θ =0

For a given time increment of Δti θ =2π

Δti | (V1 −V2 ) | hi+1 = hi + kD prdθ ∫ 2πr θ =0 Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: GIWM & UM

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: GIWM & UM

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: GIWM & UM

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: GIWM & UM

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: GIWM, UM & WP

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: GIWM, UM & WP

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: GIWM, UM & WP

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: Expt. & GIWM

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: Expt. & GIWM

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: Expt. & GIWM

Dr. V. Hegadekatte: Wear simulation of tribosystems

Twin-disc: Expt. & GIWM

Dr. V. Hegadekatte: Wear simulation of tribosystems

Micro Planetary Gear Train: WP

Dr. V. Hegadekatte: Wear simulation of tribosystems

Summary Experiment Verification

GIWM

Wear-Processor / UMESHMOTION



• •

• •

Fast tool for quick identification Wear Model (Global Scale) Limitations – Geometries, wearing surface

• •

Wear Model (Local Scale) Ideal for studies of local effects Different Geometry Computationally Expensive

Verify each other Dr. V. Hegadekatte: Wear simulation of tribosystems

A predictive modeling schemes for wear in tribometers

High surface to volume ratio. ❖ High operating speeds. ❖ Wear is a critical factor which can limit their life span. SFB 499 Model System: Micro-planetary gear ...

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