Measurement of Lift-off with Variable Amplitude Excitation in Pulsed Eddy Current Testing

Transcription

1 5 h sa Pacfc Confnc fo Non-Dsucv Tsng PCNDT07 Sngao. Masumn of Lf-off wh Vaab mu Ecaon n Pus Ey Cun Tsng J. L an G. T. Shn Chna Sca Equmn nscon an Rsach nsu Bjng Chna. Mo nfo abou hs ac: h:// bsac E-ma:shngongan@cs.og.cn Damn of Mchanca Engnng Tsnghua nvsy Bjng Chna. Masumn of f-off s bnf o assss an uc h f-off ffc n us y cun PEC sng. n hs a a sf-fnc fau h so ha h magnc fu of h a of PEC sng sgna na ncass wh h amu of caon s oos o masu h f-off whn h scmn s fomagnc. Fsy h anayca sson of h fau s sn. Scony h vay of h fau s vf by smuaon. n hn h ona facos affcng h fau a nvsga. as a quanav mho bas on h fau s monsa. Th sf-fnc fau maks h masumn convnn an ffcn. has h ona o m ngnng acaons. Kywos: Pus y cun sng vaab amu caon masumn of f-off noucon Fomagnc mac comonns a wy moy n ow ans an ochmca nusy. Thy a commony wa wh coangs whch a comos of ns o huns mm hma nsuaon an ss han mm wah shng. s a fab cana PEC sng cou assss h wa hnnng of fomagnc mac comonns whou movng h coangs an h assssmn s quck saf an mo convnn comang wh uasonc sng an aogahc sng. Howv sam as aona y cun sng PEC sng s snsv o f-off. Th vaaon of coangs hcknss whch s nvab u o h nsaaon an fomaon maks h PEC sng sus wos. n o o mov h sng accuacy masung h f-off o comnsa h sng sus s a commn aoach. hough h sng fau fo masung h f-off s acab o fomagnc maas h caon amu s consan whch s usuay h u m of a PEC sng sysm. Th caon amu shou vay wh f-off. Ohws whn h f-off casng h manc of sn co n PEC ob w ncas whch maks h a of PEC sng sgna ong o sub h a vn a of PEC sng sgna o uc h masumn accuacy of f-off an scmn hcknss. Bss h cun wh u m amu w no ony mak h sn co ha sousy whch maks h sng accuacy wos bu aso was h ngy whch s ba o omo h bay f. Thfo s ncssay o ac a fau fo masung h f-off whn h caon amu s vaaona. [D49]

2 5 h sa Pacfc Confnc fo Non-Dsucv Tsng PCNDT07 Sngao. [D49] Fau acon To h vaab amu caon h voag on h cv co cou b smua wh h anayca mo whn h scmn cov wh hma nsuaon an wah shng s aoma o a fou-ay sucu []. Fv gons cou b go by vng h n sac wh h magnc maby an h cca conucvy of ach ay. Th fquncy-oman sons ω of hamonc comonns s scb by whn a magnc nsuaon bounay s mos an h unca gon gnfuncon anson TREE mho s a h J h n n j wh j nos h magnay un ω nos h angua fquncy of hamonc comonn n nos h numb of h co uns h subscs an a on bhaf of h sn co an h c co scvy. μ 0 nos h maby of f sac ω nos h amu of hamonc comonn an j nos h cun oa on h sn co nos h nn aus of h co nos h ou aus of h co nos h boom ocaon of h co nos h o ocaon of h co J J 0 an J no h zo-o an h fs-o Bss funcon of h fs kn α nos h -h osv oo of Bss funcon J α h Гα ω nos h fcon coffcn of h ay sucu whch cou b v by Chng s ma mho []. sng nvs Fou ansfom shown n h m-oman sons cou b nuc fom ω. j Fom an s no ffcu o fn ha s ooona o h amu of. ccong o h sachs on h y cun ffuson an anuaon h magnc fu of h a of PEC sng sgna s a o h f-off [3]. 's naua o oos a fau scb by 3 o chaacs h f-off whn h amu of caon cun s vaaona. m m N S 3

3 5 h sa Pacfc Confnc fo Non-Dsucv Tsng PCNDT07 Sngao. wh m an ab h aams whch a oban a h masumn cun an h fnc cun scvy s h amu of cun an a h bgnng m an h nng m of a of PEC sng sgna [3]. 3 Smuaons n o o vfy h vay of h fau scb by 3 h anayca mo has bn moy o smua h voag on h cv co a ffn f-offs an caon amus. n h mo h hcknss conucvy an av maby of h scmn a.5 mm.6 MS/m an 600 scvy h conucvy an av maby of oh gons a 0 an h aus of magnc nsuaon bounay s h 40 ms of h numb of summaon m s 00 h oh aams a s n ab. Scay h comagnc aams of scmn a fomagnc an boh h vaaon an h nhomogny of h aams a gno n h smuaons bcaus ha h aams cou b a wh consans n PEC sng [ 4]. Paams Vau Ecaon Cun mu o 5 wh ncmns of nn aus mm 0 Sn co Hgh mm Ou aus mm Pob nn aus mm No. of uns N Rcv co Ou aus mm 79 Hgh mm 3 Numb of uns N 400 Lf-off Lmm 0 o 60 wh ncmns of 0 Tab : Paams us n h smuaons. Fgu : PEC sgnas a ffn amus of caon cun. [D49] 3

4 5 h sa Pacfc Confnc fo Non-Dsucv Tsng PCNDT07 Sngao. Fgu : Magnc fu vs. h amu of caon cun a ffn f-offs. Takng h sgnas a f-off 30 mm fo am s foun ha h sgna amu ncass wh h amu of caon cun as shown n fgu. an a abou 0.00 s an 0.06 s [3]. Whn an a s as 0.00 s an 0.06 s h magnc fu fom an s na ooona o h amu of caon cun an h so ha h magnc fu ncass wh h amu of caon s ncasng wh h f-off as shown n fgu. ncas ha h so cou b us o chaacs h f-off. 4 Dscusson Snc h a of PEC sng sgna s nnn of h scmn hcknss an s snsv o h conucvy an maby of h scmn [3] h magnc fu of h a of PEC sng sgna w hav h sma chaacscs as shown n fgu 3 an fgu 4. Fgu 3: Magnc fu vs. h amu of caon cun a ffn scmn hcknsss. [D49] 4

5 5 h sa Pacfc Confnc fo Non-Dsucv Tsng PCNDT07 Sngao. a Dffn conucvs b Dffn av mabs Fgu 4: Magnc fu vs. h amu of caon cun a ffn comagnc aams. Fom fgu 3 an fgu 4 s foun ha h so s nnn of h scmn hcknss bu s snsv o h conucvy an maby of h scmn whch ovs a gu o us h fau. 5 Quanav mho Masumn of f-off qus h quanav su whch s ha o oban fom 3. Hnc a quanav mho ncung h ss of cabaon an assssmn s monsa n fgu 5. Fgu 5: Schmac agam of h quanav mho. n h cabaon s h funcon ΔΦ=S ΔΦ- s ao o f h cuv of magnc fu vs. h amu of caon cun u o h on 0 0 s on h cuv accong o 3. n hn h nonna fng s ao o scb h aonsh bwn h f-off an h so S ΔΦ- as L S S S. n h assssmn s subsung h so [D49] 5

6 5 h sa Pacfc Confnc fo Non-Dsucv Tsng PCNDT07 Sngao. of f-off 40 mm o h cabaon funcon h assssmn su s mm an h av o s 0.%. Th quanav cson s accab. ncas ha h quanav mho bas on h sf-fnc fau h so ha h magnc fu of h a of PEC sng sgna na ncass wh h amu of caon cou b us o masu h f-off an h masumn s convnn an ffcn. 6 Concusons Wh h vaab amu caon h so ha h magnc fu of h a of PEC sng sgna na ncass wh h amu of caon cou b us a fau o masu h f-off whn h scmn s fomagnc. Th fau s nnn of h scmn hcknss bu s snsv o h conucvy an maby of h scmn. 3 Th vay of h fau shou b fuh vf by mn an h ona acaons of h fau shou b fuh o n h fuu sach. cknowgmns Ths wok s suo by Naona Hgh-v Tans Sca Suo Pan an Naona Ky Rsach an Dvomn Pan Gan No. 06YFC Rfncs [] Z Xu X Wu J L a ssssmn of Wa Thnnng n nsua Fomagnc Ps sng h Tm-To-Pak of Dffna Pus Ey-Cun Tsng Sgnas NDT & E n. vo Oc. 0. [] C C Chng C V Do W E Ds Gna nayss of Pob Cos Na Saf Conucos nnaona jouna of nonsucv sng vo [3] J L X Wu Q Zhang a Masumn of Lf-off usng h Rav Vaaon of Magnc Fu n Pus Ey Cun Tsng NDT & E n. vo Oc. 05. [4] S M van n Bg Mong an nvson of Pus Ey Cun Daa Df nvsy of Tchnoogy MG Df Nhans 003. [D49] 6