Mechanical Property Analysis with Ultrasonic Phased Array

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1 7th Word onference on Nondetructve Tetng, Oct 28, Shangha, hna Mechanca Property Anay wth Utraonc Phaed Array Wen-A SONG, Ke-Y YUAN, Y-Fang HEN, Hu-Mng YAN 2 Department of Mechanca Engneerng, Tnghua Unverty Beng 84, hna; Phone: , Fax: Ema: ongwena@nuc.edu.cn, yky@ma.tnghua.edu.cn, chenyfang@ma.tnghua.edu.cn 2 Schoo of Informaton and ommuncaton Engneerng, North Unverty of hna, Tayuan 35, hna Abtract In ttanum aoy pecmen and optc ga pecmen, the veocty of utraonc ongtudna wave, tranvere wave and qua-rayegh wave are meaured wth phaed array tranducer and gna proceng. Becaue the meaurement of the echo amptude and phae more accurate wth phaed array tranducer than a nge tranducer, the meaurement of the utraonc veocty more accurate accordngy. The method propoed n th paper can ao be ued on the optc property evauaton of optc matera. Key word mechanca property anay, phaed array, veocty of utraonc, gna proceng, optc property evauaton. Introducton It we known that whe the tetng of matera wth utraound, the accurate meaurement of the defect poton and the defect hape baed on the accurate meaurng to the veocty of the utraonc. And on the ndutra producton ne, the mechanca property (e.g. the eatc moduu) meaurement of the raw matera and the product very gnfcant for three purpoe,.e. avodng the uee machnng wth a defectve matera, mprovng the proceng technc and enurng the mechanca property of the product. The veocty of the utraonc n the od matera coud refect the mechanca property (e.g. the eatc moduu) drecty [][2][3]. Epecay, the veocty of the utraonc n the optc ga coud characterze the optc property quatatvey. So tudyng on the accurate meaurement of the utraonc veocty n matera very gnfcant. The more accurate the meaurement of the utraonc veocty coud be, the tner mechanca property changng coud be meaured. Generay, the utraonc veocty n

2 matera are meaured wth nge tranducer (echo method), or a par of tranducer (tranmt method). Becaue the bg recever aperture ung n thee two method, the gna receved by dfferent pont on the tranducer urface have dfferent phae-deay, the gna receved by the tranducer aberrated. That nfuenced the accuracy of the fght tme meaurement, and fnay refected n the accuracy of utraonc veocty meaurement. Ung the phaed array tranducer and gna proceng, the aberraton caued by the recever aperture corrected, and the accuracy of the utraonc veocty meaurement mproved. 2. meaurement of the eatc moduu The veocty of ongtudna wave n a matera, and the veocty of the tranvere wave, the denty ρ, then the foow formua coud be ued to cacuated the eatc moduu [] : 2 The poon rato: σ = () 2( ) The hear moduu: The Young moduu: 2 2 = ρ (2) G E = ρ The buk moduu: K = ρ( ) (4) 3 Accordng to the formua above, f, and ρ meaured, the eatc moduu coud be cacuated. If the veocty dynamc, then the dynamc eatc moduu coud be meaured. If the dtrbuton of the veocty meaured, the mechanca property dfference between dfferent area of the matera coud be anayzed. So the meaurement of the utraonc veocty both the bac technoogy and the key technoogy of the mechanca property anay wth utraonc. So far, ung phaed array and gna proceng meaured the veocty of the utraonc t a new drecton, n th paper a method about th propoed. 3. Meaurng the veocty of the utraonc tranmttng on the urface Wth the urface wave, the urface tre, urface hardne of a matera coud be meaured; and ao coud the eatc moduu of fm matera and homogeneou matera be meaured. Meaurng urface wave veocty wth array tranducer, the tranducer coud be et at the amed poton, the an eement of the tranducer emtted, a the eement receved, from the recevng gna t, the veocty of the urface ongtudna wave, the urface tranvere wave and the qua-rayegh wave coud meaure ntutvey. Then the mechanca property coud be anayzed. Prncpe of the meaurement hown n fgure. The dynamc photoeatc photo (fgure (a)) howed that whe an eement of the array tranducer wa emttng, there are ongtudna wave and tranvere wave tranmttng on the urface wth the repectve veocty n the pecmen, and there qua-rayegh wave behnd the urface tranvere wave. Accordngy, whe an eement of the array tranducer wa emttng, and a the eement were recevng, from the recevng gna the three veocte coud be meaured. The pecmen detected hown n fgure (b). Two near array tranducer are et a n the fgure. Each tranducer ha 24 eement. The eement ze mm 2mm, frequency 6.25 MHz. The eement are ndexed a hown n the fgure,.e.,, Λ, 47. The thckne of (3)

3 the pecmen 2 mm. Whe the eement emttng, and a the eement are recevng, the gna t hown n fgure (c). The x ax ampe pont, and the y ax the recevng eement ndex. In the fgure (d), the veocty cacuatng ne for dfferent type utraonc wave are ndcated. The veocty cacuatng ne baed on the gna t (fgure(c)), and t ope rato the veocty of the correpondng utraonc. In the fgure, ndcate the ongtudna wave on the urface, 2 the ongtudna wave n the tranducer, 3 the tranvere wave on the urface, 4 the qua-rayegh wave, 5 the echoe refect by the nterface between the two tranducer. Sgna proceng: generay, ung near array tranducer wth N eement, whe the eement emttng, and a the eement are recevng, there are N wave ere coud be receved, recorded a foow: Feher! E t ncht mögch, durch de Bearbetung von Fedfunktonen Obekte zu erteen. (5) W the recevng gna t whe the emtter eement, the upper of fgure (c) hown the recevng gna t W. w ( n),, =,,,2, Λ N ; n =,,2, Λ, M the gna receved by eement whe the emtter, M the amount of ampe pont. The 3

4 ower of fgure (c) hown the recevng gna w 6 (25). Ung fgure (d), approxmate veocty of dfferent type utraonc wave coud be etmated,.e. the ope rato of the cacuatng ne. The veocty of ongtudna wave recorded a, veocty of tranvere wave recorded a, and veocty of qua-rayegh wave. Then ung the approxmate veocty, the gna coud be eected a foow: r Feher! E t ncht mögch, durch de Bearbetung von Fedfunktonen Obekte zu erteen. (6) wn (n) a eectng wndow functon, center pont, ength 2. And, ( ) d = INT ( t / t) t = (7) coud be et a = INT ( λ /( t) ) (8) the veocty of the utraonc, and INT ( ) the rounded functon. =, =, = r, repectvey. d the center dtance between the two neghbor eement, t the tme ampng nterva, and λ the waveength whe =, =, = r, correpondngy. Accordng to the actua tuaton, dfferent wndow functon coud be changed. In th paper, the foow wndow functon ued: n + ) wn ( n) = (9) other Havng the correaton proceng between w ( n) and w ( n), pckng the maxmum t, = 2,3, Λ, N, then the ampe pont, cacuatng the deay from to, record a ( ) veocty : ( ) d / t = () = () N 2 Whe =, = ; = for = ; and = for r =. The r experment reut are hown n tabe. N = 2 Matera Tabe Meaurement of Surface wave veocty r Ttanum aoy K9 optc ga 633 m / 32 m / 275 m / 598 m / 362 m / 293 m / Under the tuaton that the eement ze mm 2mm, and frequency 6MHz, the effectve dgta of the veocty 3, f the meaurng reouton of the center dtance between the two neghbor eement hgher, more effectve dgta coud be got. 4. Veocty of utraonc nde the pecmen The gna proce mar to thoe decrbed above. Aumed that nde the pecmen, 4

5 there a catterng pont ( x y) p,, then n formua (7), changed to: r and r + r = INT ( t / t) t = (2) r the dtance between the catterng pont ( x y) p, and eement and repectvey. Havng the correaton proceng between w ( n ) and ( n ), pckng the maxmum ampe pont, cacuatng the deay ( =,,2,3,, N, ) wthw : t w, Λ, and then deang N ( n) = w ( n + ) = W (3) = INT ( t / t) (4) And havng the correaton proceng between W ( n) deay t ( =,2,3, Λ, N ), then the veocty : t and W ( n), get the = d / (5) N = = N Whe =, = ; = for = ; and = for r =. r 5. omparon experment between phaed array and nge tranducer The era nge rectange tranducer parameter, the ength 2 mm, wdth changng frommm to 2 mm. The near array tranducer ha 2 eement, and the ze of the eement 2mm. The frequency of a the tranducer 6.25MHz. Wth the ttanum aoy pecmen howed n fgure (b), ung a the tranducer to meaure the veocty the ongtudna wave. Whe ung the array tranducer, the gna proceng ued. The reut are n tabe 2. Tabe 2 omparon between phaed array and nge tranducer Wdth of tranducer ( mm ) ( m / ) Wdth of ar tranducer ( mm ) ray ( m / ) (6) For both of the amptude and the phae woud be corrected wth phaed array tranducer and gna proceng, o the gna from the array tranducer much batter than that from the gna tranducer. Fgure 2 how the gna from the array tranducer and nge from 5

6 tranducer of dfferent wdth. Fgure 3 howed the frt bottom echo gna and econd bottom echo gna ung nge tranducer of dfferent wdth. The x ax fght tme, and the y ax the wdth of the tranducer. Whe the aperture ncreaed, the phae of the recevng gna deayed more ampe pont, the ncreang of amptude not very ceary, and the gna dtorted wore. The phae deay between the frt bottom echo and the econd bottom echo cacuated by correaton anay. And the phae deay-aperture curve howed n fgure 3 (b), the x ax the wdth of the tranducer, unt mm, and the y ax phae deay between the frt bottom echo and the econd bottom echo, unt rad. Whe the wdth of the tranducer 5 mm, the phae deay got the mnmum. After that pont, the phae deay ncreaed wth the ncreang of the wdth of the tranducer. 6. oncuon From the experment reut n fgure3, t coud be concude that, whe the wdth of the tranducer mm, amptude of the recevng gna ma, and the phae meaurement of 6

7 th gna not accurate enough. The ame error ext on the econd bottom echo of 2 mm wdth tranducer. A the aperture ncreaed, the recevng gna dtorted wore, that woud add error to the fght tme meaurement. So the meaurement of the utraonc veocty wth nge tranducer n dfferent matera n dfferent ze, the aperture of the tranducer need to be choe utaby. A the error caued by the tranducer aperture n the meaurng of fght tme about n, even the tranmt dtance of the utraonc coud be meaured up to x effectve dgta, the veocty ony coud got three effectve dgta, becaue the tme meaurng error not ma enough. Th fact can be checked n tabe 2. Whe the array tranducer and the gna proceng ued, a the phae deay, and amptude dtorted corrected by th method, the reouton of the fght tme meaurement up to n, then the veocty coud get more than four effectve dgta. For the phaed array method can corrected the phae and the amptude of the gna, and can change the aperture fexby, wth th method, the meaurng to the veocty of the utraonc coud be more accuracy. And a the phaed array method ha a tattca average effect on the gna, the amptude rato between the two bottom echoe coud we refect the average attenuaton of the matera. Ung th method, the accuracy of the meaurement of the tranvere wave veocty coud be better too, and then the meaurement of the eatc moduu coud be more accurate. Whe ung the dynamc photoeatc equpment to prove the prncpe of th method, another phenomenon notced, that the optc ga wth dfferent acoutc mpendence, had dfferent optc property. So wth the utraonc veocty n the optc ga, the optc property of t coud be etmated quatatvey. The quanttatve reaton between thee two parameter need to a deeper tudy. Reference [] hen Yfang, Zhang Jaun. A Reearch on Tetng Eatc Modu of Workpece Matera. Proceedng of 4 Word onf. on NDT.996, Inda [2]HE Fang cheng, GONG Zhaobn. Utraonc Veocty Meaurng Technoogy and t Appcaton n Matera Evauaton, Journa of Matera Engneerng (8),23, [3] Roth, D.J., Martn, K, etc. ommerca Impementaton of NASA-Deveoped Utraonc Imagng Method va Technoogy Tranfer. [J ] Matera Evauaton, 996, () : [4] WEI Guo-ru, PAN Pe, etc. A new method for accurate meaurement of the veocty of uperonc wave Journa of X'an Unverty of Archtecture & Technoogy(Natura Scence Edton), 36(3),24,

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