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@PHDTHESIS{ZABEEN:96256,
author = {ZABEEN, SURAIYA and DESY},
title = {{F}atigue {C}rack {G}rowth in {C}omplex {R}esidual {S}tress
{F}ields {D}ue to {S}urface {T}reatment and {F}oreign
{O}bject {D}amage under {S}imulated {F}light {C}ycles},
school = {The University of Manchester},
type = {Dissertation},
address = {Manchester},
publisher = {The University of Manchester},
reportid = {PHPPUBDB-21609},
pages = {230},
year = {2011},
note = {Dissertation, The University of Manchester, 2011},
abstract = {Foreign object damage (FOD) refers to the damage that
generally takes place in aero engine fans and compressor
blades, due to the ingestion of hard particles/debris during
aeroplane take-off, taxiing, or landing. Such damage can
reduce the fatigue life expectancy of the turbine engine
components by $50\%.$ Residual stresses and small
microcracks induced by the high speed FOD impacts are two
root causes that result in premature failure of these
components. One way to mitigate the FOD related fatigue
failure is to induce deep compressive residualstress into
the surface. Among the available techniques that can induce
such compressive residual stress, laser shock peening (LSP)
has been found to be beneficial in improving the fatigue
strength. In this study aerofoil-shaped Ti-6Al-4V leading
edge specimens were laser shock peened. Subsequently, FOD
was introduced onto the leading edge specimenthrough
ballistic impacts of a cube edge at angles of 0° and 45°
to the leading edge. The effect of foreign object damage
(FOD) on the pre-existing compressive residual stress field
associated with the laser shock peening (LSP), and its
change upon solely low cycle fatigue (LCF) as well as
combined low and high cycle fatigue cycling has been
studied. The residual stress distribution and their
redistribution upon fatigue cycling were mapped around the
FOD notch, using synchrotron X-ray radiation and the contour
method. The results suggest that under both impact angles,
the FOD event superimposed a significant additional residual
stress on top of the pre-existing stress associated with the
LSP process. It has been observed that the FOD notch created
by 45° impact was asymmetric in shape, and had differential
notch depth between the entry and exit side. However, FOD
damage that is created at 0° impact appeared as a sharp V
notch. A higher amount of residual stresses were produced
under 0° impact condition than at 45°. It has been found
even though the FOD inducedresidual stresses relax, residual
stresses due to LSP treatment remain highly stable even in
the worst condition where a 7 mm long crack was grown from a
45° notch. The plastic zone sizes ahead of a crack tip was
estimated for both 0° and 45° FOD impact, and the fatigue
crack growth rates are predicted utilizing the measured
residual stress distribution.},
keywords = {Dissertation},
cin = {HASYLAB(-2012) / HZG},
cid = {$I:(DE-H253)HASYLAB_-2012_-20130307$ /
I:(DE-H253)HZG-20120731},
pnm = {PETRA Beamline P07 (POF2-54G14) / DORIS Beamline W2
(POF2-54G13)},
pid = {G:(DE-H253)POF2-P07-20130405 / G:(DE-H253)POF2-W2-20130405},
experiment = {EXP:(DE-H253)D-W2-20150101 / EXP:(DE-H253)P-P07-20150101},
typ = {PUB:(DE-HGF)11},
url = {https://bib-pubdb1.desy.de/record/96256},
}