Fraunhofer IWS
BRT: WP2013_1.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Jrgen Klinsmann Silvia Neid Henry Maske
Jens Weiflog Mats Wilander Michelle Obama
Rumul-Symposium 17-19th September 2014
Fraunhofer IWS
BRT: WP2013_2.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Next time we might get into business
I want that chair and expresso machine included in the offer!
Fraunhofer IWS
BRT: WP2013_3.ppt
Competences at Fraunhofer IWS, Dresden
Material, component and process characterization
Chemical surface and reaction
technology
PVD- and Nanotechnology
Joining
Surface Technology
Thermal coating and additive
manufacturing
Ablation and cutting
Laser material processing Surface and coating technology
Fraunhofer IWS
BRT: WP2013_4.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Prof. Dr.-Ing. Martina Zimmermann
Professur fr Werkstoffprfung und
-charakterisierung
Institut fr Werkstoffwissenschaft
TU Dresden
Fraunhofer Institut fr
Werkstoff- und Strahltechnik, Dresden
Fraunhofer IWS
BRT: WP2013_5.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Material Characterization at Fraunhofer IWS, Dresden
Mechanical behavior
under application
relevant loads
Characterization
of macro to nano
layers
Failure analysis
e.g. laser hardening e.g. windscreen
wipers
e.g. x-ray mirrors z. B. Schaufelabriss
an Turbolader
1m 2 nm
Microstructure
on demand
Fraunhofer IWS
BRT: WP2013_6.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
(micro)
structure
mechanical
properties
Process &
design
optimization
Material Characterization at Fraunhofer IWS, Dresden
Fraunhofer IWS
BRT: WP2013_7.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Challenges in the experimental characterization of the fatigue behavior in the VHCF regime
and its significance for the identification of failure-relevant defects
regular grain boundary
twin boundary
Fraunhofer IWS
BRT: WP2013_8.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Me, when I started working in
the field of VHCF!
Fraunhofer IWS
BRT: WP2013_9.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Outline
Introduction
Damage Mechanisms in VHCF
Challenges for Testing Strategies
Conclusion
Fraunhofer IWS
BRT: WP2013_10.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Fatigue crack growth
lg d
a/d
N
lg D K
Loading conditions
Load collective
Fatigue Properties
Material
S-N-curve (directives, component tests)
Damage accumulation
(& numerical integration)
lg s
A
lg N
s
lg n
Fatigue Life
Geometry Processing
Relevant fatigue property = classical durability?
Fraunhofer IWS
BRT: WP2013_11.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
ICE-wheels:
daily performance 1425 km
= daily about N =
0,5x106
= total life N = 7x108
aus Internetseiten des LBF, Darmstadt und Bhmer et.
al.: Dynamik u. Festigkeit von gummi-gefederten
Radreifen
Fatigue strength up to N = 107 no longer sufficient?
S
iem
en
s
Steam turbine:
rotations: 3000/min or 1500/min
Product life ~ 25.000 h
= N = 4,5x109 resp.
N = 2,25x109
WE-powertrain:
Slow rotation: 18-50/min Transformator: 1500/min = daily N=2,1x106 (under full-
loading conditions)
Fraunhofer IWS
BRT: WP2013_12.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Damage Mechanisms: Basic Assumption
Mu
gh
rab
i (2
00
2, 2
00
4, 2
00
6):
Material Type I
pure, annealed and ductile with no
(extrinsic) interior defects
roughening of the surface through
irreversibility of heterogeneous plastic
deformation
Material Type II
with inclusions, dispersoids, pores
etc.
size, position and distribution of the
inclusion, hardness (acc. to Murakami)
Damage mechanism dominated by:
Damage Mechanisms in the VHCF-Range
Inclusion
Facet
Specimen
surface
AISI 304, N > 107
Fraunhofer IWS
BRT: WP2013_13.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Damage Mechanisms and S-N-curves
M. Zimmermann: Int. Mater. Review, 2012
Fraunhofer IWS
BRT: WP2013_14.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Influence of microscopic notches becomes the fatigue life dominating parameter
Fatigue crack initiation and crack growth
in 1.4301 at non-metallic inclusion, failure
at N = 1,49 x 108
Change in damage mechanism is possible
Damage Mechanisms and S-N-curves
Crack initiation changes from surface to subsurface region
Fraunhofer IWS
BRT: WP2013_15.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Microstructural Inhomogeneity
Fraunhofer IWS
BRT: WP2013_16.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
microcracks at Ds/289.5MPa and N=6x108
formation of dislocation cell structure at
Ds/294MPa and N=1.2x1010.
Sta
nzl-Tsch
eg
g, S
ch
oe
nb
auer,
In
t. J
. F
atig
ue
, 2
01
0
isolated dipole bundles
in the VHCF regime
surface roughening at
N > 1010 cycles at 150 MPa
Sto
ecke
r e
t a
l.,
Int.
J.
Fatigu
e, 2
011
pure copper pure nickel
Damage evolution in the VHCF regime
Fraunhofer IWS
BRT: WP2013_17.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Nickel-base superalloys
Damage evolution in the VHCF regime M
iao
et a
l., A
cta
M
ate
r.,
20
09
J. Miao et al. (2009)
Fraunhofer IWS
BRT: WP2013_18.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Nickel-base superalloys Nimonic 80A
Damage evolution in the VHCF regime
Be
an
spru
chun
gsrichtu
ng
/2 = 454 MPa; Nf=2,01106
/2 = 410 MPa; Nf=2,09107
regular grain boundary
twin boundary 360
380
400
420
440
460
480
500
0 10 1'000
stre
ss a
mp
litu
de
, MP
a
number of cycles to failure, 106
Hochgesezte Proben
Brche
Durchlufer
pre-fatigued
failure
run-out
Fraunhofer IWS
BRT: WP2013_19.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Aluminium alloy EN AW-6082
Damage evolution in the VHCF regime
void formation at the crack initiation site in the vicinity of
primary MgSi-particles (due to size identified as primary
particles resulting from the initial casting process)
Cremer et al., submitted to Int. J. Fatigue, 2012
Fraunhofer IWS
BRT: WP2013_20.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Challenge in the characterization of damage evolution
Nickel-base superalloys Nimonic 80A
Fraunhofer IWS
BRT: WP2013_21.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Challenge in the characterization of damage evolution
Metastable austenitic steel
in the fully austenitic condition
Fraunhofer IWS
BRT: WP2013_22.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Challenge in the characterization of damage evolution
Metastable austenitic steel
in the fully austenitic condition
Fraunhofer IWS
BRT: WP2013_23.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Challenges for test procedure
misalignment
unwanted heating
crack initiation at
surface flaws
Ma
ye
r e
t a
l.,I
nt.
J.
Fa
tig
ue
, 2
00
9
representative
microstructure &
sample volume true strain distribution
residual stresses
Fraunhofer IWS
BRT: WP2013_24.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Challenges for test procedure
What should be the new finite number of cycles to failure?
Sample preparation?
Tested volume fraction?
Statistical evaluation of the fatigue results (how to deal with run-outs)?
Defined testing conditions (temperature, air humidity etc.)
Defined reference testing for frequency influence?
Consideration of residual stresses?
Standardization of test procedure for the VHCF regime?
How to define the true loading condition on a microstructural basis?
Fraunhofer IWS
BRT: WP2013_25.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Characterization of
Inhomogeneity
Probability of
Occurance
Capability of Crack
Propagation
type and size
position
strength mismatch
anisotropy
distribution
damage relevance
crack growth threshold
influence of
- temperature
- strain rate
- air humidity
Life Prediction Curve including
Microstructural Notch Effect
+
Threshold for Crack Growth
Reliable Life Prediction
Microstructural
Notch Factor
Kf,micro
for da/dN < 10-10
? Microstructural Crack
Growth Threshold
DKVHCF- Thres
Fraunhofer IWS
BRT: WP2013_26.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Monte Carlo Simulation
Statistical Model
Stress distribution
Size distribution
of inclusions
Position of inclusion Position of inclusions
Distribution of inclusion
in the fatigue sample and
in the real component
Probabilistic Modelling & Reliable Life Prediction
Fraunhofer IWS
BRT: WP2013_27.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Early Crack Detection by indirect methods
Detection of crack initiation (also from sample interior)
Fraunhofer IWS
BRT: WP2013_28.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Early Crack Detection by indirect methods
N = 3107
2%
21C 95%
26 C 97%
41C 99%
85C 100%
98C
0.5 mm
1 mm
N = 2106
Fraunhofer IWS
BRT: WP2013_29.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Primal forming
e.g. casting
Forming
e.g. beding
Cutting
e.g. punching Joining
e.g. welding
Modifying
inherent
properties
Coating
Inhomogeneity through Processing
Even higher complexity in damage evolution to be expected!
Fraunhofer IWS
BRT: WP2013_30.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Very High Cycle Fatigue Behavior of Welded Structures
GW WEZ SN
Welding defects
Weld geometry
s
R
b
microstructure
Fraunhofer IWS
BRT: WP2013_31.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Very High Cycle Fatigue Behavior of Welded Structures
Fraunhofer IWS
BRT: WP2013_32.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Very High Cycle Fatigue Behavior of Welded Structures
VHCF strength is dominated by weld defects
Fraunhofer IWS
BRT: WP2013_33.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Summary
Me (Us?) and the current state of the art in VHCF research!
Fraunhofer IWS
BRT: WP2013_34.ppt Lehrstuhl fr Werkstoffprfung und -charakterisierung
Prof. Dr.-Ing. M. Zimmermann
Many thanks
to the organizers of this colloquium for the invitation to give this lecture! to the audience for their interest in my talk! to my very ambitious and hard working PhD students Christian Stcker, Carsten Mller-Bollenhagen, Martin Cremer, Andrei
Grigorescu, Philipp Hilgendorff, Anton Kolyshkin!
to the german research foundation and the RWTV Stiftung for financial support
Prof. Dr.-Ing. Martina Zimmermann
Tel. 0172 1645855
E-Mail: [email protected]
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