Transient Thermal Analysis of Friction Stir Welding using 3D-Analytical Model of Stir Zone

Transcription

1 36 특집 : 마찰교반접합 Tansien Themal Analysis o Ficion Si Welding using 3D-Analyical Model o Si Zone Bang Hee Seon and Bang Han Su Inoducion Ficion Si Welding is a solid sae joining mehod wih ive phases o acions in is enie pocess. The is is he plunging peiod, whee he pin is ully and shoulde is paially plunged ino he join line o he wok piece. The second acion is in he dwell peiod duing which he ool keeps on oaing a he plunge poin. In his phase he maeial aound he ool is heaed due o he icion beween he pobe and maix suaces due o sliding acion. Due o his hemo-mechanical acion, maeials aound he ool ge plasicized. The hid phase o acion is in he seady sae welding peiod, duing which he oaing ool is avesed along he welding line. This is ollowed by a second dwell peiod, which is he ouh phase o acion. The las and he ih phase o acion is in he eleasing peiod duing which he oaing ool is aised up om he weld line leaving behind a pin caviy in he wok piece. In he FSW model o William he meal low zones ae caegoized as shoulde zone, exusion zone and voex swil zone, and hese zones ae deined using egula geomeies. In his pesen sudy shoulde zone and he voex swil zone ae deined same as William s model. Bu he exusion zone has been deined using moe accuae geomey and based on Askai s conceps a combined analyical and inie elemen based model has been developed o hemal disibuion analysis o FSW pocess and he hemal hisoy in he Si zone, Hea aeced zone and he base meal has been deemined. Expeimenal Pocedues Wok piece geomey and deails. The FSW seup consiss o wo 1mm hick Al6061 plaes, 70mm wide and 100mm long. The plaes ae joined such ha he disance beween he plunging poin and he eleasing poin is 60mm. The ool is made o SKD-51 ool-seel, having shoulde heigh o 0mm and diamee o 3mm. The pin has a heigh o 9mm, uppe and lowe diamee o and 8.30mm especively. Welding paamees. FSW was peomed a a oaion speed o 600 pm and a welding speed o 50mm/min, ool-o-wok piece angle was mainained a appoximaely.5 and an eecive plunge deph o 9.1mm. A hese values o he welding paamees an adequae welding qualiy was obained. Tempeaue measuemen. Thee expeimens wee conduced a a avel speed o 50mm/min and 600 pm vaying he measuing deph o 3mm, 6mm and 9mm especively. Each o his expeimen he empeaues wee ecoded a 4 locaions in he advancing side and 4 along he eeaing side. The 1mm diamee holes wee pe-dilled om he op suace o he plae and hemo couple o 1mm diamee wee imly ixed in o hese holes ae clamping he plae in he FSW machine. The empeaue om he hemocouple is measued when he ool pin is beween he saing 580 Jounal o KWJS, ol. 6, No. 6, Decembe, 008

2 Tansien Themal Analysis o Ficion Si Welding using 3D-Analyical Model o Si Zone 37 line and sopping line as shown in Fig. 1. The digial signals om he hemocouple wee conveed o hemals hisoy gaphs and daabase using he Labview package in he compue conneced o he SC-345 caie. Analyical model In ode o ge he volume o hea inpu o Finie elemen analysis, he volume o he ool has been deduced om he oal volume o he exusion zone, shoulde zone and voex swil zone. The Advancing uppe and lowe exusion zone and eeaing lowe exusion zone has been deined using paabolic geomey and he Reeaing uppe exusion zone by geomey as shown in Fig.. The volume pe uni ime o he die caviy omaion om Fig. 3 can be wien as = ( R p1 R p h (1) DC ) Fig. 3 The die caviy omaion deails o FSW pin Fig. 4 Thee Dimensional FE model used o esidual sess analysis o FSW; (a) Elemens a he die caviy; (b) Elemens aound he die caviy(hea inpu elemens) olume o he maeial moving hough he exusion zone is given by e a = () whee volume o he maeial moving hough he Advancing side o exusion zone Fig. 1 Schemaic o empeaue measuemen duing FSW o Al6061 volume o he maeial moving hough he Reeaing side o exusion zone olume o he maeial moving hough he Reeaing side o exusion zone is given by = uppe lowe die caviy (3) Fig. Schemaics o meal low paen model o FSW and shape o he vaious sub zones in SZ uppe lowe = = s u ( ) W λδ h. 3 R 4 s l ( ) W λδ h. R 4 (4) (5) 大韓熔接 接合學會誌第 6 卷第 6 號, 008 年 1 月 581

3 38 Bang Hee Seon and Bang Han Su olume o he maeial moving hough he Advancing side o exusion zone is obained as a = 3 ( ) W λδ h a Assuming he maeial moved down one ead pich (1/λ) pe evoluion, oal downwad moion is obained as Z = ω / λ (7) Toal volume pe uni ime o he shouldepocessed maeial is given by ( R R ) * h / s = ω s p s λ (8) I is also assumed ha he shoulde maeial ills he volume vacaed by he downwad moion. The plasicized meal is no allowed o expand eely due o he conainmen o is solid suounding and he axial oce om he ool. This esul in he expulsion o meal a he op suace and he oaion o he ool anspo his expulsed meal and deposied hem in he eeaing side. In his wok his volume is assumed as ~4% s depending on he oaion speed. Equaing he low o mass balance will esul he equaion as e DC (6) = 0.98s (9) By consideing quadaic ems o geneal suace equaion, we aive a he nine-em bi-quadaic uncion: h i = a 00 a 10 x a 01 y a 0 y a 1 x y a 0 x a 1 x y a 11 x y a x y (10) Occasionally, he x y em is omied, So he equaions o he heigh o shoulde voex and exusion zone om he above suace plos shown in Fig. 5 ae h S = (11) h = E h W E (1) = (13) 6 = (14) Based on he equaion o he analyical model and bi-quadaic uncion o heigh o shoulde voex exusion zone and widh o he si zone an excel wok shee as shown in he Fig. 6 has been ceaed o calculae he dimension o he si zone based on he welding paamees. Thus he widh o eeaing and advancing side wee calculaed. Using his value he adial disance o he bounday o hea inpu volume om he axis Fig. 5 Shoulde, Exusion, oex zone heigh and Widh o exusion o vaious oaions and anslaional speed o he ool 58 Jounal o KWJS, ol. 6, No. 6, Decembe, 008

4 Tansien Themal Analysis o Ficion Si Welding using 3D-Analyical Model o Si Zone 39 Fig. 6 Excel calculaion shee o deeminaion o he dimensions o he si zone based on he Ficion si welding paamees o he ool has been deemined in boh advancing and eeaing side and he adial disance a he leading side was inepolaed om hese values a vaious level (along he hickness diecion). Thus he hee dimensional analyical model o he hea inpu volume has been ceaed and based on his he inie elemen hea anse analysis has been caied ou. FE Hea Tanse Analysis To deemine he hemal hisoies o he Ficion Si welding pocess he inie elemen hea anse analysis has been caied ou (Comini e al). The hee dimensional FE model employed in his wok is shown in he Fig. 4. The Solid bick elemen has been used o modeling and he oal numbe o nodes and elemens ae and 8100 especively. A suicienly ine mesh a he si zone, hemo-mechanically aeced zone and hea- aeced zone was geneaed o obain moe accuae esuls. The maeial used o he modeling was Al 6061 and he empeaue dependen physical popeies applied o he FE hea anse analysis. Resuls and Discussion Resuls o FE based Hea anse analysis. The hee dimensional empeaue disibuion conous obained om he FE hea anse analysis ae shown in Fig.7a and 7b. In ode o have a clea inside view o he 3D model, slice secion along he lengh widh and hickness has been ploed. Compaison o Numeical and Expeimenal Resuls In ode o compae hese esuls wih he expeimenally measued values, he hemal disibuion gaph o deph o 3mm, 6mm and 9mm ecoded a 4 locaions in he advancing side and 4 along he eeaing side is shown in he Fig. 6. and he coesponding numeically obained value o ime =.0 sec is shown in he Fig. 7 and om he gaph i can be seen ha boh he values ae compaable. The esimaed maximum empeaues ae abou 467 C in he si zone and 306 C in he HAZ. The numeically simulaed empeaue value a om he weld zone has deviaion om he expeimenal esuls, as he hemal diusion em is no consideed in he numeical model. 大韓熔接 接合學會誌第 6 卷第 6 號, 008 年 1 月 583

5 40 Bang Hee Seon and Bang Han Su 500 Advancing side Reeaing side 450 Tempeaue( ) Disance om he weld line (mm) Fig. 8 Tempeaue disibuion a vaious dephs o FSW o 50-avel speed and 600-oaion speed measued using hemocouple 500 Advancing side Reeaing side 400 Fig. 7 Tempeaue disibuion conou on he slice (a) along he hickness diecion (3mm, 6mm and 9mm om he op) (b) along he widh diecion (a 0mm, 5mm, 10mm and 15mm om he ool axis along advancing and eeaing side) Conclusion The analyical model used o he hea inpu in he hea anse analysis has been demonsaed o a paicula ool geomey and maeial popey. Based on his sudy ollowing conclusions can be dawn. 1. The model can be used o accuaely model he hea disibuion along he uniom pocessing zone o FSW beween he plunging and eleasing poions.. The hee-dimensional asymmeic hea disibuion abou he ool has been accuaely modeled and expeimenally validaed o Al 6061-T6 1mm hick plae FS welding. 3. The asymmey in he hea disibuion is due o he asymmey in he plasicized maeial volume along he advancing and eeaing side o he si zone. Tempeaue( ) Disance om he weld line (mm) Fig. 9 Tempeaue disibuion a vaious dephs o FSW o 50 avel speed and 600 oaion speed obained using he analyical model and non linea hea anse analysis. (a ime, =.0sec) λ : Theads pe inch Nomenclaue δ : Pojeced head aea W a : Widh o advancing exusion zone W : Widh o eeaing exusion zone W s : Aveage widh o shoulde zone ΔZ : Disance maeial moves down pe evoluion q Sa, q S : Rae o hea geneaed F S : Shea plane componen o esulan oce R p1, R p : Radius o pin a op and boom R s : Radius o shoulde v : Fowad avel speed v : Pin angenial velociy = R p ω 584 Jounal o KWJS, ol. 6, No. 6, Decembe, 008

6 Tansien Themal Analysis o Ficion Si Welding using 3D-Analyical Model o Si Zone 41 v s : elociy o maeial in shoulde zone ω : Roaion speed h : Pin lengh h s : Deph o shoulde pocessing zone h a : Deph o advancing side exusion zone h : Deph o eeaing side exusion zone Bang HeeSeon D.O.B Dep. o Naval Achiecue Engineeing, Chosun Univesiy Sucue and Welding Mechanics banghs@chosun.ac.k Reeences 1. P.Colegove, M.Paine, D.Gaham, and T.Mille: 3-Dimenional low and hemal modeling o he Ficion Si Welding pocess, CSIRO, Souh Ausalia, (000). Y.J.Chao, and X.Qi: Hea anse and hemo- mechanical analysis o Ficion Si joining o Al6061-T6 plaes, 1s Inenaional Symposium on Ficion Si Welding, (1999) 3. A.Askai, S.Silling, B.London, and M.Mahoney: Modelling and Analysis o Ficion Si Welding Pocesses, Ficion si welding and Pocessing, TMS publicaion,(001) A.William, Using Gleeble low sess daa o esablish opimum FSW pocessing paamee in Aluminium Alloys, Advanced maeial pocessing cene, (00) 5. G.Comini, S.D.Giudice, and C.Nonino: Finie Elemen Analysis in Hea Tanse Taylo & Fancis, Ialy, (1994) Bang HanSu D.O.B Dep. o Naval Achiecue Engineeing, Chosun Univesiy Sucue and Welding Mechanics hsbang@chosun.ac.k 大韓熔接 接合學會誌第 6 卷第 6 號, 008 年 1 月 585