IEC 61 400 23 Edition 1 0 201 4 04 INTERNATIONAL STANDARD Wind turbines – Part 23 Full scale structural testing of rotor blades IE C 6 1 4 0 0 2 3 2 0 1 4 0 4 (e n ) ® colour inside Copyright Internat[.]
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Trang 4CONTENTS
FOREWORD 5
INTRODUCTION 7
1 Sco e 8
2 Normative ref eren es 8
3 Terms an definition 9
4 Notation 12 4.1 Symb ls 12 4.2 Gre k s mb ls 12 4.3 Subs ripts 12 4.4 Co rdinate s stems 12 5 General prin iples 13 5.1 Purp se of tests 13 5.2 Limit states 14 5.3 Practical con traints 14 5.4 Res lts of test 14 6 Doc mentation an proced res f or test blade 15 7 Blade test program and test plan 16 7.1 Are s to b tested 16 7.2 Test program 16 7.3 Test plan 16 7.3.1 General 16 7.3.2 Blade des ription 16 7.3.3 L ad an con ition 17 7.3.4 In trumentation 17 7.3.5 Exp cted test res lts 17 8 L ad f actors for testin 17 8.1 General 17 8.2 Partial safety factors u ed in the desig 17 8.2.1 General 17 8.2.2 Partial f actors on materials 17 8.2.3 Partial f actors f or con eq en es of f ai ure 18 8.2.4 Partial f actors on lo d 18 8.3 Test lo d factors 18 8.3.1 Blade to blade variation 18 8.3.2 Pos ible er ors in the f atig e f ormulation 18 8.3.3 En ironmental con ition 19 8.4 Ap l cation of lo d factors to o tain the target lo d 19 9 Test lo din an test lo d evaluation 2
9.1 General 2
9.2 Influen e of lo d introd ction 2
9.3 Static lo d testin 2
9.4 Fatig e lo d testin 21
10 Test req irements 2
10.1 General 2
10.1.1 Test record 2
10.1.2 In trumentation cal bration 2
Trang 510.1.3 Me s rement u certainties 2
10.1.4 Ro t fixture an test stan req irements 2
10.1.5 En ironmental con ition monitorin 2
10.1.6 Deterministic cor ection 2
10.2 Static test 2
10.2.1 General 2
10.2.2 Static lo d test 2
10.2.3 Strain me s rement 2
10.2.4 Deflection me s rement 2
10.3 Fatig e test 2
10.4 Other blade pro erty tests 2
10.4.1 Blade mas an center of gravity 2
10.4.2 Natural f eq en ies 2
10.4.3 Optional blade pro erty tests 2
1 Test res lts evaluation 2
1 1 General 2
1 2 Catastro hic fai ure 2
1 3 Permanent def ormation, los of stiff nes or c an e in other blade pro erties 2
1 4 Sup r icial damage 2
1 5 Faiure evaluation 2
12 Re ortin 2
12.1 General 2
12.2 Test re ort content 2
12.3 Evaluation of test in relation to desig req irements 2
An ex A (informative) Guidelnes for the neces ity of renewed static an fatig e testin 2
An ex B (informative) Are s to b tested 2
An ex C (informative) Ef fects of large def lection an lo d direction 3
An ex D (informative) Formulation of test lo d 31
D.1 Static target lo d 31
D.2 Fatig e target lo d 31
D.3 Seq ential sin le-axial, sin le location 3
D.4 Multi axial sin le location 3
An ex E (informative) Dif feren es b twe n desig an test lo d con ition 3
E.1 General 3
E.2 L ad introd ction 3
E.3 Ben in moments an s e r 3
E.4 Fla wise an le d-lag combination 3
E.5 Radial lo d 3
E.6 Torsion lo d 3
E.7 En ironmental con ition 3
E.8 Fatig e lo d sp ctrum an seq en e 3
An ex F (inf ormative) Determination of n mb r of lo d c cles for fatig e tests 3
F.1 General 3
F.2 Bac grou d 3
F.3 The a pro c u ed 3
Bibl ogra h 4
Trang 6Fig re 1 – Chordwise (flatwise, ed ewise) co rdinate s stem 13
Fig re 2 – Rotor (fla wise, le d-lag) co rdinate s stem 13
Fig re C.1 – Ap l ed lo d eff ects due to blade deformation an an ulation 3
Fig re D.1 – Polar plot of the lo d en elo e fom a typical blade 31
Fig re D.2 – Desig FS F 3
Fig re D.3 – Are where desig FS F is smal er than 1,4 (critical are ) 3
Fig re D.4 – rFSF an critical are s, seq ential sin le-axial test 3
Fig re D.5 – rFSF an critical are , multi axial test 3
Fig re E.1 – Dif feren e of moment distribution for target an actual test lo d 3
Fig re F.1 – Simplfied Go dman diagram 3
Fig re F.2 – Test lo d f actor γ ef f or diff erent n mb r of lo d c cles in the test 4
Ta le 1 – Recommen ed values for γ ef for dif ferent n mb r of lo d c cles 18 Ta le A.1 – Examples of situation typical y req irin or not req irin renewed testin 2
Ta le F.1 – Recommen ed values f or γ ef for dif ferent n mb r of lo d c cles 3
Ta le F.2 – Exp n ed recommen ed values for γ ef f or dif ferent n mb r of lo d c cles 41
Trang 7INTERNATIONAL ELECTROTECHNICAL COMMISSION
_
Part 23: Ful -scale structural testing of rotor blades
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International Stan ard IEC 614 0-2 has b en pre ared by IEC tec nical commite 8 : Win
turbines
This f irst edition can els an re laces IEC TS 614 0-2 , publ s ed in 2 01 It con titutes a
tec nical revision
This edition in lu es the folowin sig if i ant tec nical c an es with resp ct to
IEC TS 614 0-2 :
a) des ription of load b sed testin only;
b) con en ation to des ribe the general prin iples an deman s
Trang 8The text of this stan ard is b sed on the f ol owin doc ments:
Ful information on the votin for the a proval of this stan ard can b f ou d in the re ort on
votin indicated in the a ove ta le
This publcation has b en drafted in ac ordan e with the ISO/IEC Directives, Part 2
A l st of al p rts in the IEC 614 0 series, publs ed u der the general title Wind turbines, can
b f ou d on the IEC we site
The commit e has decided that the contents of this publ cation wi remain u c an ed u ti
the sta i ty date in icated on the IEC we site u der "ht p:/webstore.iec.c " in the data
related to the sp cific publ cation At this date, the publ cation wi b
• with rawn,
• re laced by a revised edition, or
A bi n ual version of this publ cation may b is ued at a later date
IMPORTANT – Th 'colour inside' logo on the cover pa e of this publ c tion indic te
that it contain colours whic are consid re to be us f ul f or the cor e t
understa din of its conte ts Us rs s ould theref ore print this doc me t usin a
colour printer
Trang 9The blades of a win turbine rotor are general y regarded as one of the most critical
comp nents of the win turbine s stem In this stan ard, the deman s f or ful -s ale stru tural
testin related to certification are defined as wel as the interpretation an evaluation of test
res lts
Sp cific testin method or set-ups for testin are not deman ed or in lu ed as f ul -s ale
blade testin method historical y have develo ed in e en ently in diff erent cou tries an
la oratories
Furthermore, deman s for tests determinin blade pro erties are in luded in this stan ard in
order to val date some vital desig as umption u ed as inputs for the desig lo d
calc lation
An of the req irements of this stan ard may b altered if it can b s ita ly demon trated that
the saf ety of the s stem is not compromised
The stan ard is b sed on IEC TS 614 0-2 publs ed in 2 01 Comp red to the TS, this
stan ard only des rib s lo d b sed testin an is con en ed to des rib the general
prin iples an deman s
Trang 10WIND TURBINES –
Part 23: Ful -scale structural testing of rotor blades
This p rt of IEC 614 0 defines the req irements for f ul -s ale stru tural testin of win turbine
blades an for the interpretation an evaluation of ac ieved test res lts The stan ard
f oc ses on asp cts of testin related to an evaluation of the integrity of the blade, f or u e by
man facturers an third p rty in estigators
The fol owin tests are con idered in this stan ard:
• static lo d tests;
• f atig e tests;
• static lo d tests after fatig e tests;
• tests determinin other blade pro erties
The purp se of the tests is to con rm to an ac e ta le level of pro a i ty that the whole
p pulation of a blade typ fulfis the desig as umption
It is as umed that the data req ired to define the p rameters of the tests are avaia le an
b sed on the stan ard f or desig req irements f or win turbines s c as IEC 614 0-1 or
eq ivalent Desig lo d an blade material data are con idered startin p ints for
esta l s in an evaluatin the test lo d The evaluation of the desig lo d with resp ct to
the actual lo d on the win turbines is outside the s o e of this stan ard
At the time this stan ard was writen, ful -s ale tests were car ied out on blades of horizontal
axis win turbines The blades were mostly made of fibre reinforced plastic an wo d/e ox
However, most prin iples would b a pl ca le to any win turbine con g ration, size an
material
The folowin doc ments, in whole or in p rt, are normatively ref eren ed in this doc ment an
are in isp n a le f or its a pl cation For dated referen es, only the edition cited a pl es For
u dated referen es, the latest edition of the referen ed doc ment (in lu in an
amen ments) a pl es
IEC 6 0 0-415:19 9, I ntern tion l Ele trot ec nic l Vo a ulary – Part 415: Wind turbine
g n rator systems
IEC 614 0-1:2 0 , Wind turbin s – Part 1: Design re uireme ts
ISO/IEC 17 2 :2 0 , Ge eral re uireme ts for t he c mp ten e of t esting a d c l ibrat io
l ab rat ories
ISO 2 9 :19 8, Ge eral prin iples o rel iabil ity for stru tures
Trang 11integrated set of items that ac ompl s es a def i ed o jective or fu ction within the blade (e.g.
l g tnin protection s bs stem, a rod namic brakin s bs stem, monitorin s bs stem,
a rod namic control s bs stem, etc.)
3.4
buc l ng
in ta i ty c aracterized by a non-l ne r in re se in out of plane deflection with a c an e in
local compres ive lo d
3.5
len th of a ref eren e straig t l ne that join the le din an trai n ed es of a blade a rof oi
cros -section at a given sp nwise location
Note 1 to e try: Strictly s e kin , n s c ln e ists e c pt f or a few c n itio s of lo din Us aly th ela tic
a is is a s me to b th ln th t p s e thro g th ela tic c nter of e ery s ctio This d f i itio is n t
a plc ble for bla e with b n -twist c u ln
3.1
f atigue f ormulation
Trang 12direction that is p ralel to the plane of the swe t s rf ace an p rp n ic lar to the lon itu inal
axis of the u def ormed rotor blade
partial s fety fa tors
f actors that are a pl ed to lo d an material stren th to ac ou t for u certainties in the
re resentative (c aracteristic) values
Trang 13S-N f ormulation
method u ed to des rib the stres an /or strain (S) v c cle (N) c aracteristic of a
material, comp nent or stru ture
Trang 14lf en ironmental ef fects: fatig e
lu en ironmental ef fects: static
nf con eq en e of f ai ure: f atig e
n con eq en e of f ai ure: static
sf blade to blade variation: f atig e test lo d
s blade to blade variation: static test lo d
target target lo din con ition
test test lo din con ition
4.4 Coordinate s stems
Two diff erent co rdinate s stems may b u ed for ref eren e d rin stru tural testin The
first, s own in Fig re 1, ref eren es the local blade c ord direction The secon , s own in
Fig re 2, ref eren es the glo al rotor plane direction
Trang 15Figure 1 – Chordwis (flatwis , e gewis ) coordinate s stem
Figure 2 – Rotor (f lapwis , le d-la ) coordinate s stem
5 Ge eral principles
5.1 Purp s of te ts
The fu damental purp se of a win turbine blade test is to demon trate to a re sona le level
of certainty that a blade type, when man factured ac ordin to a certain set of sp cification ,
has the pres rib d rel a i ty with referen e to sp cif i l mit states, or, more precisely, to verify
that the sp cified l mit states are not re c ed an the blades therefore p s es the lo d
car yin ca a i ty an service lfe provided for in the desig
L a s are alo g th rotor pla e
ref ere c dire tio s
M
zTorsio mome t
F
xFla wis s e r f orc
1 Fla wis tra slatio
2 L a -la tra slatio
M
cTorsio mome
t
F
aFlatwis s e r forc
1 Torsio a gle
2 Fla wis tra slatio
3 L a -la tra slatio
IE C 10 0/4
Trang 16Ad itional y, tests determinin blade pro erties have to b p rf ormed in order to val date
some vital desig as umption u ed as inputs for the desig lo d calc lation It has to b
p inted out that the req ired blade pro erty tests do not cover al desig as umption
Normal y, the f ul -s ale tests de lt within this stan ard are tests on a l mited n mb r of
samples; only one or two blades of a given desig are tested, so no statistical distribution of
prod ction blade lo d car yin ca a i ty can b o tained Althou h the tests do give
inf ormation val d for the blade typ , they can ot re lace either a rigorou desig proces or
the q al ty s stem f or series blade prod ction Furthermore, the tests des rib d in this
stan ard are not inten ed to b u ed f or the testin of mec anism f un tion nor to esta l s
b sic material stren th or fatig e desig data f or blades an /or comp nents
5.2 Limit state
To esta l s an evaluate the test lo d, a certain amou t of information a out the desig s al
b k own Us al y the blades are desig ed ac ording to some stan ard or code of practice
s c as IEC 614 0-1 that u es the prin iples of ISO 2 9 def i in the lmit states an partial
co ff i ients, whic have to b a pl ed to o tain the cor esp n in desig values A l mit state
is a state of the stru ture an the lo d actin up n it, b yond whic the stru ture no lon er
satis es the desig req irements The p rtial co ff i ients ref lect u certainties an are c osen
– at le st in prin iple – in order to ke p the pro a i ty of a l mit state b in re c ed b low a
certain value pres rib d for the stru ture Ac ordin to this, a blade s ould p s the test if the
l mit state is not re c ed when the blade is exp sed to the test lo d, re resentative of the
desig lo d
The b sis f or esta l s in the test lo d is the entire en elo e of blade desig lo d , derived
ac ordin to IEC 614 0-1 or eq ivalent The re resentative test lo d can b hig er than the
desig lo d to ac ou t for other in uen es, f or example, en ironmental ef fects, test
u certainties, an variation in prod ction (se Clau e 8)
The determination of the actual margin to the lmit states mig t b desira le b cau e s c
margin can provide a me s re of the actual safety o tained for the resistan e of the test
blade However, interpretation of s c values is not straig tf orward an pro a i stic method
have to b a pl ed In this stan ard, only the ultimate lmit state an fatig e are de lt with
5.3 Pra tic l constraints
The practical exec tion of the tests is s bject to man con traints of a tec nical an economic
c aracter Some of the most imp rtant are l sted b low:
• the distributed lo d on the blade can b simulated only a proximately;
• the time avaia le for testin is general y one ye r or les ;
• only one or a f ew blades can b tested;
• certain fai ures are diff i ult to detect
The test wi b a compromise b cau e these con traints have to b de lt with in s c a way
that the final test res lts can b u ed f or evaluation of the defined l mit states
As regard the interpretation of the res lts, it s ould b b rne in min that the blade u ed for
testin wi normal y b one of the first blades fom series prod ction whic wi b s bject to
evolutionary modif i ation Even minor modif i ation could compromise the val dity of the
tests (se An ex A)
5.4 Re ults of te t
The desig lo d form the b sis of the test lo din Ac ordin to the desig calc lation, the
blade s al b a le to s rvive the desig lo din In these desig calc lation , a n mb r of
as umption are impl citly b in made:
Trang 17• the stres es or strain are calc lated ac urately or con ervatively estimated;
• the clas ification of stren th an fatig e resistan e of al relevant materials an detai s
are estimated ac urately or con ervatively;
• the stren th an f atig e f ormulation u ed to calc late the stren th are ac urate or
con ervative;
• the prod ction is ac ordin to the desig
In a f ul -s ale test u ed as f i al desig verif i ation, the valdity of the as umption mentioned
a ove are c ec ed simultane u ly When a blade f ais d rin testin , at le st one of these
as umption has b en violated, althou h without f urther analy is it mig t not b cle r what
cau ed this u exp cted faiure
If no damage to the blade has oc ur ed d rin the test an the blade stru ture an the test
lo din has b en evaluated cor ectly, this gives a stron in ication that the blade desig wi
f ulf il its req irements It s ould b noted that the blade pro erty tests make it p s ible to
c ec some of the main desig as umption u ed f or the desig calc lation
6 Documentation and proc dures f or test blade
The blade man f acturer s al record trace ble doc mentary eviden e for the desig an
con tru tion of the test blade The record s ould cover:
• u iq e identification;
• relevant drawin s an sp cification ;
• lamination plan an work in tru tion ;
• l stin of man facturer, typ an identif i ation n mb r f or al imp rtant materials u ed;
• s p ler’s certif i ate an blade man f actures la oratory ac e tan e re ort f or al imp rtant
materials u ed;
• c rin history thermogra h for thermosetin resin an ad esives at critical location ;
• dif ferential s an in calorimetry or other control of c rin ;
• man f acturin q al ty record s e ts sig ed by resp n ible p rson;
• weig t an b lan e re ort detai n total mas an centre of gravity This re ort s al
in lu e inf ormation a out an lo se items fit ed d rin weig in e.g ro t joint elements
an damp r fluid ;
• relevant re orts on man f acturin deviation
Re airs s al also b doc mented The record s ould cover the a ove l st Re airs may b :
• re resentative examples for re air proced res for man f acturin def ects an in-service
damage that are q alfied with the test blade;
• re airs p rf ormed d e to damage cau ed by test lo d hig er than the target lo d (se
9.3 an 9.4)
Sp cial blade modification can b present for test purp ses Durin the f atig e tests the
lo d may have to b mag ified to complete the test within an ac e ta le time-f rame In some
cases, the req ired mag ification of the fatig e lo d may le d to faiure of are s not
con idered to b tested In these cases, sp cial blade modification can be con idered
Modification mig t also b d e to lo d introd ction reinforcements Al sp cial blade
modification s al b doc mented
Trang 187 Bla e test program and test plans
7.1 Are s to be te te
No sin le test can lo d the whole blade o timal y Al critical are s s ould b lo ded at a
minimum to the target lo d These are s are dis u sed in An ex B L ad-lag an fla tests
• p st fatig e static tests
Testin of other blade pro erties could b of interest (se 10.4.3)
Al tests in a given direction an in a given are of a blade s al be p r ormed on the same
blade p rt The fla an le d-lag seq en e of testin may b p rormed on two se arate
blades However, if an are of the blade is critical d e to the combination of fla an le d-lag
lo din , then the entire test seq en e s al b p rf ormed on one blade
The test program s al in lu e blade in p ction (se Clau e 1 )
The blade des ription in the test plan s al b s ff i ient to en ure that the blade wi fit the
test stan an avoid u inten ed overlo din d rin storage, han ln , l ftin , mou tin an
testin in the la oratory
The f ol owin information s al b s p l ed:
• blade ge metry (pref era ly in form of a drawin ):
– b lt p t ern (in lu in toleran es) an inter ace dimen ion;
– b lt size, typ an grade;
– b lt clampin len th;
– b lt preten ion or torq e proced re;
Trang 19• l f tin an han l n proced res;
• maximum exp cted deflection u der lo d;
• profi e ge metry at lo d introd ction p ints
Ad itional inf ormation (s c as mou tin stru ture stif fnes ) may b req ired de en in on
the test sp cific
7.3.3 Loa s a d conditions
The test plan s al in lu e the target lo d , test lo d , a plcation method an seq en e of
the tests to b con u ted En ironmental con ition that may aff ect the exec tion of the tests
s al also b given in the test plan (se 8.3.3)
7.3.4 Instrume tation
The p sition an orientation of lo d cel s, strain gau es, deflection tran d cers an other
sen ors s al b sp cified in the test plan
7.3.5 Expe te te t re ults
It is recommen ed that prediction (deflection , strain , etc.) are provided cor espon in to
al sen or me s rements to ena le an as ist plan in , evaluation an q al ty control
8 Load f actors f or testing
In testing, variou lo d factors have to b taken into ac ou t Those arisin f rom the desig
are dis u sed in 8.2 Ap rt f rom these, ad itional test lo d factors have to b a pl ed to
ac ou t for eff ects introd ced by the test methodolog These test lo d factors are dis u sed
: p rtial material factors;
γ : p rtial f actors f or con eq en es of f ai ure;
8.2.2 Partial f actors on materials
Material data are normal y b sed on tests of coup n prod ced an tested u der la oratory
con ition
Material con ersion f actors take into ac ou t sp cif i dif feren es b twe n the con ition of
the material in the stru ture an the con ition for whic the stren th an fatig e formulation
were derived Examples of these con ersion factors are factors for size ef fects, h midity,
agin an temp rature These wi b a pl ed impl citly u in the a pro riate stren th an
Trang 20The p rtial factor f or materials, γ
m, is a pl ed in the desig to ac ou t f or u certainties in the
con ersion factors an the p s ibi ty of u favora le deviation of the material pro erties fom
the c aracteristic values The test lo d s ould not b in re sed by this p rtial factor (γ
m)
b cau e the material in the blade b in tested is the actual material
8.2.3 Partial f actors for cons que c s of f ai ure
The p rtial f actors f or con eq en es of fai ure, γ , ac ordin to IEC 614 0-1, are f actors by
whic the imp rtan e of the stru ture an the con eq en es of f ai ure, in lu in the
sig ifican e of the typ of f ai ure, are taken into ac ou t
1
The re son is that for a non-ai
-saf e comp nent (s c as a blade) a hig er level of safety again t f aiure is req ired than f or a
f ai -safe comp nent In this case, the ful -s ale test s al reflect this ad itional saf ety
req irement As a con eq en e, these factors s al b in lu ed in the test lo d
8.2.4 Partial f actors on loa s
Durin the desig , the p rtial f actors on lo d γ
ftake into ac ou t the u certainties in the
lo d Therefore, the test blade s al b a le to resist the desig lo d (whic in lu es the
a pro riate p rtial f actors for lo d )
8.3 Te t loa fa tors
8.3.1 Bla e to bla e v riation
If there is no f aiure pro a i ty distribution data avai a le f or the p rtic lar blade desig an
p rtic lar man facturin proced re, the f ol owin test lo d f actors s al b u ed:
The static lo d f actor a ove s al b u ed for at le st one of the two req ired static tests (pre
or p st fatig e) For the other static test, γ
ucan b set to 1,0
8.3.2 Pos ible er ors in the fatigue f ormulation
Due to the con ersion of the original fatig e desig lo d to f atig e test lo d , an u certainty
is introd ced d e to p s ible er ors in the fatig e formulation
The more the f atig e test is ac elerated, i.e the lower the n mb r of c cles in the f atig e
test, the larger the u certainty con ected to the con ersion f om the f atig e design lo d to
Number of load cycle
γ
f
5 × 105
1,0 5
1 × 106
1,0 0
2,5 ×106
1,0 5
5 × 106
1,0 5
1 × 107
Trang 21For fatigue tests u in a n mb r of lo d c cles diff erent f rom those given in the ta le a ove,
γ
f
is either con ervatively selected or f ou d by interp lation or extra olation
8.3.3 En ironme tal con itions
In general, the con ition at the test f aci ty are more b nig than the actual o erational an
con eq ently desig con ition In man stren th an fatig e f ormulation , the ef fect of these
con ition is expres ed by factors However, it can also res lt in diff erent stren th or fatig e
f ormulation for the dif ferent condition
When the test con ition are more b nig , this le d to a mag if i ation of the req ired test
lo d The a pro riate factor has to b c ec ed by the evaluation of the test lo d distribution,
but for b th con ition the a pro riate stren th or fatig e f ormulation has to b a pl ed (se
An ex E) Whenever the eff ect is given by f actors, these can b u ed as an initial estimate for
the factor neces ary to mag ify the lo d to ar ive at an eq ivalent test lo d
8.4 Appl c tion of loa fa tors to obtain the targ t loa
For the tests, the desig lo d is compi ed into a target lo d The test lo d s ould ide l y b
eq ivalent to the target lo d The determination of the target lo d s al b b sed on
a pro riate stren th an /or f atig e formulation an elastic pro erties for the materials u ed
in the are s to b tested
The target lo d for the static test is defined as:
γγγ
lusundu-
t arg t
is the test lo d f actor for en ironmental ef fects, if a pl ca le (se 8.3.3)
The target lo d for the fatig e test is def i ed as:
γγγγ
lfefsfnfdff
t arg t
is the test lo d f actor f or en ironmental ef fects, if a pl ca le Alternatively the
en ironmental eff ects can b ac ou ted f or in the con ersion f rom desig lo d to
damage eq ivalent desig lo d , if a pl ca le (se 8.3.3)
The determination of the damage eq ivalent desig lo d for fatig e in lu es a pro riate S-N
f ormulation(s), c cle cou tin proced res, an a pro riate damage s mmation model, R-value
eff ects, an al other relevant information
Trang 229 Test loading and test load evaluation
For e c test, the target lo d s al b defined in the test plan Suf ficient inf ormation s al b
provided to al ow the test lo d to b ac urately as es ed again t the target lo d In prin iple,
the six lo d comp nents s ould b given, in lu in phase an feq en y information req ired
to generate combined lo d cases In re l ty, the lo d comp nents le d-lag an fla wise
moments are the f ar most imp rtant comp nents L ad-lag an fla wise s e r lo d wi
normal y implcitly b taken care of b cau e of the moments Only for more sp cial zed blades
wi the torsion an len thwise forces have to b taken into ac ou t The co rdinate s stem
relevant f or the lo d comp nents s al b cle rly sp cified (se 4.4) The large def lection of
the blade d rin testin typical y le d to c an es in lo d direction with mag itu e (se
An ex C) Eff ects of c an es in lo d direction s al b careful y con idered when pre arin
the test plan an re orts an when estimatin u certainties ac ordin to 10.1.3
Sin e the test s ould prove that the blade can s rvive the target lo din , the test lo din s al
b evaluated It s ould b c ec ed in whic are s of the blade the severity of the test lo din
is in e d eq al to or more severe than the target lo din Becau e the severity of the test
lo din comp red to the target lo din wi vary over the blade are , in prin iple the
evaluation has to b done at al location of the blade are that are to b tested Some
examples of test evaluation are presented in An ex D
L ad on critical mec anical an electrical blade s bs stems, s c as tip brakes an l g tning
protection comp nents, are of ten dif ferent in c aracter f rom the general lo d on the blades
an may ne d extra sp cif i ation an sp cific tests In the case of mec anisms, it is u l kely
that s ff i ient lo din con ition wi b present in the stan ard tests to q al fy the s bs stem
integrity Ad itional testin may b neces ary to simulate sp cial case lo din , in lu in
torsion an radial lo din For s stems whose fai ure may res lt in u saf e o eration of the
turbine, sp cial con ideration s al b given to verify the a pro riate level of stru tural
integrity The ac umulated damage s ould not cau e fu ctional fai ure of these s bs stems
L ad f or testin of blade s bs stems are not covered further in this stan ard
9.2 Inf lue c of loa introduction
In the case where the test lo d is introd ced as con entrated f orces at a restricted n mb r of
location (e.g at actuator p sition ), the section where the lo d is a pl ed are disturb d an
may b stren thened over a certain are by the lo d introd ction fixtures Therefore, at these
are s the blade may not b pro erly tested an s ould not b con idered in the analy is or
evaluation The len th (in the lon itu inal direction) of the disturb d are can b estimated
f rom calc lation or me s rements
Without further analy is, it could b as umed that this af fected are mig t exten as mu h as
thre q arters of the c ord len th on either side of the f i ture In sad le desig , sp cial
at ention s ould b given to bu kl n sen itive are s (e.g trai n ed e in compres ion)
Also, if sp cial modification are made for test purp ses (se Clau e 6), the a ove-mentioned
con ideration are relevant
9.3 Static loa te ting
In static lo d testin , the are to b tested s al b lo ded to e c of its most severe desig
lo d con ition whi e takin into ac ou t the variation in a p pulation of man factured
blades an dif feren es b twe n the la oratory an the desig en ironmental con ition (se
8.3.1 an 8.3.3)
If diff erent lo d distribution or orientation are ne ded to re resent the dif ferent extreme lo d
cases in the are s to b tested, e c of these s al b a pl ed For dis u sion of lo d
direction , se Clau e D.1
Trang 23It s ould b noted that the blade may b most v lnera le to certain faiure modes when a
res ltant lo d, whic is not neces ari y the hig est in mag itu e, is a pro riately a pl ed in a
p rtic lar direction For e c lo d the blade s al with tan the maximum lo d for the
sp cified lo d d ration Sin e most common blade materials ex ibit a red ction of stren th
with d ration of lo d, the d ration of the test lo d s al b at le st as lon as the pe k desig
lo d If the design lo d inf ormation provides a wel -defined d ration for the p ak lo d on the
blade, the test lo d an d ration s al b b sed directly on that If no d ration of con tant test
lo d is stated, then 10 s s al b the minimum value
In general al location wi b regarded as s ff i iently tested if the lo din d rin the static
lo d test is eq al to or hig er than the target lo d In case of fai ures cau ed by lo d hig er
than target lo d , re air is al owed b fore a f atig e test
If the blade is tested with combined lo din , it is not inten ed to combine maximum lo d in
one direction with maximum lo d in the other direction In te d, the maximum lo d in one
direction s ould b combined with an a pro riate lo d in the other direction
9.4 Fatigue loa te ting
On the are s to b tested, a test lo din has to b generated givin a fatig e damage
eq ivalent to the fatig e damage cau ed by the target lo d The fatig e test lo d wi
general y b c osen in s c a way that, f or practical re son , the test time is red ced To test
are s arou d the whole blade cros -section, variou combination of f latwise an ed ewise
lo din may b employed
To red ce the n mb r of c cles d rin the test, the lo d normal y has to b in re sed to
o tain a re sona le compromise b twe n testin as re lstical y as p s ible an o tainin a
more re sona le testin time
The mag if i ation s al le d to the a pro riate the retical eq ivalent fatig e damage
ac umulation, havin the fol owin lmitation in min :
• the maximum values of the stres es or strain mig t s rp s the static stren th of the
material an con eq ently le d to static damage or f aiure;
• the stres es or strain may b so hig that the u ual as umption of the lne rity b twe n
f orces an stres es no lon er a ples, s c as in the case of bu kl n ;
• internal he tin of the hig ly stres ed are s
Esp cial y in the case of varia le ampltu e lo din , these l mits can b re c ed at a
relatively low lo d mag if i ation factor In that case, only the intermediate lo d c cles can b
in re sed further, an the test lo din b comes more an more a con tant-ampl tu e lo din
as a con eq en e
The me n lo d a pl ed d rin f atig e testin s al normal y b as close as p s ible to the
me n lo d at the o eratin con ition that are most severe to the f atig e stren th
L cation wi b regarded as s f ficiently tested if the the retical damage (e.g Miner
s mmation) d rin the f atig e test is eq al to or hig er than the the retical damage b sed on
the target lo d
The the retical test damage can b evaluated by ac umulation of the damage fom al p rtial
tests
When a certain are of the blade f ais af ter it has b en s bjected to the retical damage d e to
the test lo d that is equivalent to or hig er than the damage d e to the target lo d, that are
has p s ed the test In prin iple, testin of the blade can contin e to re c eq al severity for
the other are s This is only val d f or the are s that are not aff ected by stres redistribution
d e to the damage
Trang 24In case of f ai ures cau ed by lo d hig er than target lo d , re air is al owed The
con eq en es of any re airs s al b evaluated
10 Test requirements
10.1 Ge eral
10.1.1 Te t re ord
Al test activities s al b noted in a log b ok
10.1.2 Instrume tation c l bration
Al in trumentation u ed to col ect data for evaluation of test res lts s al b cal brated In the
case of a pl ed sen ors an gau es that can ot b in e en ently calbrated, sp cification
s al b trace ble an the remainin c ain s al b cal brated Proced res for control n ,
cal bratin , maintainin an in p ctin me s rin an test eq ipment s al b develo ed an
implemented in ac ordan e with ISO/IEC 17 2 or eq ivalent When p s ible, an en -to-en
cal bration of the s stem s ould b made, verifyin p rf orman e of al s stem comp nents In
the proced res, it s al b ad res ed that recal bration has to b done for sen ors that mig t
b damaged as a con eq en e of a catastro hic blade or eq ipment fai ure d rin testin
2
10.1.3 Me s reme t unc rtaintie
Al device u certainties s al b l sted in the test re ort
In ad ition, the fol owin u certainties s al b estimated an re orted:
• u certainties in mag itu e, direction an location of an a pl ed lo d;
• u certainties in mag itu e, direction an location of displacement;
• u certainties in mag itu e, direction an location of the me s red strain
3
10.1.4 Ro t fixture a d te t sta d re uireme ts
In case the ro t are an f i ture is con idered for testin , deviation b twe n the test stan
an the win turbine blade as embly s al b evaluated
The me s red deflection of the blade s ould b cor ected for deformation of the blade ro t
f i ture an the test stan F r the me s red natural f eq en ies, dampin an mode s a es,
the ef fect of the test stan s al b con idered For relatively rigid test stan s (contribution to
tip deflection les than 1 %), the ef fect of the test stan can b ig ored
10.1.5 Environme tal con itions monitoring
En ironmental record may b neces ary to q antify eff ects on the test blade s c as
stif fnes variation , strain gau e drif t (p rtic larly on sin le element brid es) or drif t in other
sen ors
_ _ _ _ _ _
2
Faiure of th bla e or e uipme t c n re ult in o erlo din a s n or s c a a lo d c l Du to th p s ible
stro g d n mic ef fe ts, this o erlo din ma b pre e t d rin s c a s ort p rio th t it mig t n t b (uly)
d te te b th me s reme t s stem
3
Th tolera c of a strain g u e is ty ic ly smaler th n 1 % Howe er, strain g u e are of te ma e of
materials th t are mu h stif fer th n th c atin s a d a h siv s u e in win turbin bla e d sig This imple
th t strain g u e d sig ma h v a imp ct o re din s wh re strain g u e are a ple o th s rf ac of
thic c atin s a d a h siv s Su h re din s o th s rf ac of thic c atin s a d a h siv s ma n t b
re re e tativ for th strain in lamin te b low th c atin or a h siv Ap lc tio of larg strain g u e or
remo al of c atin b grin in ma re u e th dif fere c b twe n th strain g u e re din a d th tru strain
in th lamin te