xac djnh anh hu^ang cua nhiet do den dac tinh dan hoi nhat cua be tong deo bang thi nghiem phan tich dong dma
identfication ofthe temperature effect on the visco-elastic behavious of plastic concrete by the dynamic mechanical analysis test
Ngay nhan bai: 18/11/2014 Ngay sij^ bai: 20/12/2014 Ngay chap nhan dang: 10/01/2015
T O M
TAT:
Bii bao nay tr'mh bay nghien eflu vifc flng dung thi nghiem phan tich dpng (DMA) de xac dinh cae thong so d i n hfli nhflt cua bf tong deo khi chiu tac dpng thay doi cCia nhiet dp moi trUflng tfl 5oC den 50oC. Cac thong so nay ducrc sfl dung cho mo hinh luu bien Maxwell eai tifn, phat trifn bcfi Le [3], du^c lap trinh bing ngon ngfl Fortrans, tich hpp trong tinh nang mfl UMAT ciia chUPng trinh tinh toan theo phfldng phap phan tfl hi3u hgn Abaqus. Do tin cay cua cac thong so xac dinh dU0c va mo hinh dupc kiem chflng thong qua viec so sanh ket qua mo phdng vfli k£t q u i thi nghifm nfn dpc true tinh va dpng fl eie dieu kif n nhift do Ichae nhau.
TH khfla; Be tong dfo, Tinh chat dan hoi nhflt, Nhiet dp, Thi
nghifm DMA, Matlab, Abaqus.
ABSTRACT
This paper studies the application of the Dynamic Mechanical Analysis test (DMA) to identify the effect of temperature which varies from 5oC to 50oC, on the visco-elastic parameters of plastic concrete. These parameters are used for the modified Maxwell model, which have been built-up by Le [3], implanted in the subroutine UMAT of the FEM logieial Abaqus, written by the language Fortrans. The rehability of these identified parameters and the model were examined by the comparison between the modelling results and the experimental results of the static and dynamic compression tests under the different temperature conditions.
Key words: Plastic concrete, Visco-elastic behavious.
Temperature, Dynamic Mechnica! Analysis Test, Matlab, Abaqus.
TS.Le Viet Dung
BQ mon Cong trinh Be tong cot thep - Tnrong Dai hpc Xay
D}fng. Email: dunglv(gnuce.edu.vnLe V i e t D u n g
I.DATVAND£ i TU nhCfng nam 90, m o t loai be tong eo dac tfnh b f t ddi xUng g\6ie
be tong t h u d n g , d 6 n khi k f o , dan nhdt deo khi n^n. duoc nghifn cilu sCrdung trong cau kien chju lUc bao che cac nguyen lieu nang l u g n g ^ Ph^p. Loai be tong nay dUoe san xuat theo phUOng phdp nen nhift dif luc cao sau khi trdn cdc hat cap phoi nho, mjn vcri chat ket dfnh co t r ^ phu gia deo v6i hdm lUcmg nho vai phan tram. Tinh chat chju luc kfm khi keo, t o t khi nen ciia vat lieu duac quan sat ban dau trong hlnh 1. vdi thi n g h i f m keo, n^n l^p thuan tiiy, vd n^n lap trong thf n g h i f m nen 3 true [3].
Ttnh c h i t lUu b i f n , ddn nhcrt d f o khi nen ciia vat l i f u da duoc phin tich ro trong nghien cUii thuc nghiem, t h o n g qua eae t h i nghiem tU bifn, chung utig suat va keo nen vdi toe d o gia tai khac nhau [3,4,5].
Kinlil:Ketquattifn9hiemkeonenlapt}iuantOyvanen3tnicvoiaplucbolOMPs[3].
Hinh 2: Ket qui do ihi;
suit - bien dang then tW gian cda mau tru b^Uiiig 111 diiu til trong nen d K 6 t n | j VCing lap t i e ' d i l t t i M M i ! dug suat-giiim tat-hoi pliA biendang'dcacmitcnhielH 5'C.2(K:,35'C,5(K.
D|c tfnh tren eiia vat lieu dUoe mo phong bSng m 6 hinh lUu b i f n Maxwell cdi t i f n [3,5], gom cde nhdnh lUu b i f n Maxwell mac song song v6i nhdnh dan d f o {hlnh 3).
r A A H ^
AAro—
Hlnh 3: Mo hinh lUu bien Maxwell d l tien [3,S) Do dae thii trong khau sdn x u f t ciia vdt l i f u , vifc tdn tai c h f t k f t dinh vdi phu gia d f o duoc ddnh gia la nguyen nhan chinh gay nen tfnh nhdt ciia vdt l i f u . D 6 n g thdi vifc f p n f n c f p phdi hat trong d i f u ki^n nhiet dd vd ap luc cao
; dd t^o nen mdt mang cau true vat l i f u , cd dac ( tinh ch[u dnh hudng cOa dp lue bd vd n h i f t d 6 I mdi trudng trong qua trinh chju luc cua vSt ll^u.
, Su dnh hudng ciia dp lUe bd d f n tfnh chat ,^ CO I]? cOa vdt l i f u da dUac danh gid trong [5].
J Trong n g h i f n cOU nay. dnh hudng cua n h i f t d 6 ,. duoc phan tfch t h d n g qua cac t h i nghiem nen u tinh, ddng khdc nhau. Hlnh 2 eho phep quan . sdt rd rdng su dnh hudng nay ciia nhi^t dd den , dac tinh dan hdi nhdt cua vat li§u, t h o n g qua sU chenh lech bien thien cOa Ung suat trong cac pha thf n g h i f m ehft tdl vd chCing ung suat img vdi cdc trudng hop n h i f t d ^ khdc nhau, cung n h u sU chenh 16ch bien thifen cua b i f n dang trong pha hoi phue b i f n dang quan sdt duoc khi Ung s u i t dupc giU dn djnh d trang thai khdng tdi trong 1 khodng thdi gian 30 phUt.
Su dnh hudng nay eCia nhl&t dfl se dupe phdn tfch cu the hon trong t h i nghiem phdn tieh ddng DMA d phSn sau, tU d d cho phep xdc djnh cdc thdng sd dau vJo cOa m6 hlnh Maxwell cdi t i f n nhSm hd tro bdi toan md phdng ddc tfnh co hoc eiia vat li^u nghien cUu.
2. NGHIEN CQUTHUC NGHIEM Hai phuong phdp thf nghiem nen tmh vdi vdng lap t r f va nen phan tich dgng DMA dUOC si!rdung trong n g h i f n eUu.
Hinh 6 gidi thieu mot vdng lap tre trung g i a n T c O a t h f n g h i f m , gom 4 giai doan. (i) giai doan ehSt tdl A^B-(li] gial doan ehiing u'ng suf t BjC, - (iii) giai doan gidm tdi C,D - giai doan hdi phuc bien dang D^A^,. D d cUng dan hdi cua vdt lieu d t h d i diem chat tdi t h U T d U p e xdc dinh bdi dudng thiing ndi 2 d i f m C, vd A^,.
Xac dinh thdng sd dan hdi nhdt eua vat lieu Mo dun dan hdi
Suthay doi d d ciing dan hdi (dd ddc dudng C A^^,) sau mdt vdng lap tre khi tdi trong tang dupc xdc djnh trong Hinh 5. Nhdn t h f y r i n g dp cO'ng cua vdt lieu gidm dan khi tai trong tang, sU glcim dan eua do cdng nay dUoe gidi thich bdi sU hlnh thdnh va phat t r i f n ciia cde khe vi ndt trong vdt l i f u khi Ung suat k f o chinh trong vdt ll^u tang [1,2].
;-Ci(UFi)
- Ddl vdi md hinh luu b i f n n h i f u nhanh n h u Maxwell cdi t i f n , viec chf dung hai dang t h i nghiem t r f n se gap khd khan trong viee xac dinh ehfnh xdc eae thdng sd cOa t d n g nhdnh rieng biet
Do dd, de xac dinh dUpc mdt each tin tUdng cdc t h d n g sd ddn nhdt d f o eua cdc nhanh vdi sd lupng t h i nghi&m it n h f t co the, phutmg phap t h i n g h i f m phan tich ddng DMA (Dynamic Mechanical Analysis) dUpe iUa chpn, do phUdng phdp nay ed mot sd Uu diem nhU:
- LUdng vdt l i f u sd dung it. Chi can mpt t d mau tru kich thude 3x3x50 m m .
- Thf n g h i f m DMA dUpc thUC h i f n trong pham VI Ung suat be vdi bien d p dao ddng nhd, do dd vat lieu dUOc phdn tich trong vimg dan hdi nhdt chua xdy ra b i f n dang du.
Vdi quy md t h i n g h i f m nay, v i ^ ap dung cae mUe nhiet dd khdc nhau la don gidn.
Trong thf nghiem DMA, sU gia tdi bSng bien dang dUpc k i f m soat ed dang hlnh sin:
e = ejSin(ut) (1) vdi bien d d e^ - 0,01%. Kft qud phdn tieh
trang thai Ung suat trong mau thu dUdc dUpc chia lam hai thanh phan ddng pha (thUc) va lech pha (do) vdi b i f n d^ng. Do do 2 thdnh phan thuc vd do eua mo dun dan nhdt ed dang nhu
E = ^ c o s ( 9 ) eo
(2)
Kft qud thuc nghifim do dupe eua 2 thanh phan m d dun ddn nhdt nay dupc t h f h i f n trong Hinh 6.
Hinh 5 SU giim dan do ci^g d^n hoi cua vit li^u lihi 6ng suit (trangthii diem C) ting
Quan sat k f t qud thuc n g h i f m phan tieh trong Hlnh 5, nhan thay t h i nghiem k f o Idp cho k f t qud phan tan. do d d vifec xdc dinh md dun ddn hdi eCia vdt l i f u duoe xae dinh dua vao k f t qud thi nghiem n^n lap. theo phuong phap ndi suy tiep tuyen dUdng cong v f gdc d trang thdl bSt dau chat tai. Theo phUcmg phap ndi suy, k f t qud do cho gid tri eiia md dun dan hdi d mdi mUc n h i f t dd t h u dupe ed dp phan tdn nhU trong Bdng 1.
Thdng sd dan hdi nhdt E^ - q^ cua nhdnh t h d j Thdng thudng. thdng sd dan nhdt d f o ciia vat lieu dUde xac dinh thdng qua cac thf nghiem t i / b i f n hay chung Ung suat. Tuy nhif n, vdl loai be tdng d f o nghien cdu trong bai bdo nay, phuang phdp tren gap mdt sd khd khan sau:
- Khi van tde gia tal Idn, trong khodng thdi gian ng^n (vdi giay), sU k i f m soat tdi trong dn dinh trong thi nghiem rat phUc tap.
i ™
" • - " •
^
- " • * "
Hmh 6: Ket qui So dio hai thanh phin thut (trIt) va ao (phii) cda mo dun dan nhdt trong thinghiem DMA.
Vdl md hinh da nhdnh Maxwell cdi t i f n . hai thanh phan eua m d dun dan nhdt trong t h i n g h i f m DMA dUpe xdc dinh theo ham t h d n g sd eua edc nhanh md hinh Maxwell cdi t i f n n h u
Hlnh 4: Cac di jm dac trung xic dinh dac tinh vat \\iu trong 1 vong tip tre'dilt lil - thiing dng suit - giim tai - hoi phuc bien dang"
Bdng 1:Ket vdng lap t r f
Nhiet dd ED (MPa)
qua md dun dan hdi phu thudc nhi&t do xac d m h b3ng thf nghigm nen tTnh vdi
s-<.
3400+200
20 "C 2900±100
35 "C 2600±150
5 0 - t 2350±150
j=l 1- E . = l E j
'Jil
j = i l+{Ti.ro]^
(5)
vdi khodng thdi gian t r i m g Ung su^t cua nhdnh luu bien t h U j .
5d nhdnh eua m d hlnh lUu b i f n Maxwell cdi t i f n vd cdc t h d n g sd E„ (Md d u n dan hdi). E^ vd q {Md d u n ddn nhdt ciia nhanh j) dUoe xdc dmh bSng cdch can ehfnh khdp k f t qud ciia phuong trinh 4.5 vdi k f t qud thUe nghiem d o d Hlnh 6.
3. K ^ T Q U A V A T H A O L U A N Budng cong E|^^^ vd E^^ xdc djnh theo phuong trinh 4 vd 5 duoc t h i f t lap bSng phSn m f m MatLab. Kft qud dupe so sanh phan tfch trong Hinh 7, trong dd sd nhdnh tdl Uu xac dinh dUcfc la 10 nhdnh. Cdc thdng sd dan nhdt dio eda vat li^u dupc xdc dinh trong Bdng 2 vd Bdng 3.
Nhdn thiy gid trj m d d u n ddn hdi ciia vdt l i f u xdc dinh bdng thf nghiem DMA trong Bdng 2 eho k f t qud ehinh xac, ndm trong khodng ehay dupe xdc dinh theo phuong phdp nen tinh t h d n g t h u d n g cho trong Bdng 1. K f t qud ndy d o dd duoc sd d u n g n h f m ddnh gid khd nang dp dung m d hlnh Maxwell cdi t i f n trong bdi todn m d phdng dac tfnh cd hpc cua vat lieu nghi&n Thudt todn phdt tnen tir m d hlnh lUu b i f n Maxwell cdi t i f n d f cdp d tr#n dupe lap trinh bSng ngdn n g d FORTRAN, tich hpp vdi tfnh ndng ngudn m d Subroutine UMAT cCia chuong
Bdng 2: M d d u n dan hdi ciia vdt liSu xdc djnh bSng t h i n g h i f m DMA
Hlnh 7; Soi chieu mo ph6ng ket qua thi nghiem DMA bing Matlab vdl mo hlnh Maxwell ci tien gom 10 nhanh.
trinh phdn m f m tinh toan ABAQU5 theo phuong phdp phan t d hUu han (PTHH) [3]. K f t qud m d phdng dUdc ddi c h i f u so sdnh vdi thitc n g h i f m trong cac Hinh 8 , 9 , 1 0 , 1 1 .
Hinh 8 gidi t h i f u ket qua so sdnh gida m d phdng vdi thuc n g h i f m trong t h i nghiem DMA d nhiet d d 20°C: sdu t r u d n g hpp chat tdl ddng ed tan sd gdc w khac nhau duoc phdn tfch m d phdng. K f t qua phan tich so sdnh cho thciy tfnh khd t h i ciia m d hinh Maxwell edi tien. Bdi todn m d phdng theo Abaqus eho k f t qud triing khdp vdi k f t qud thuc n g h i f m .
D d t i n cay ciia thf n g h i f m DMA trong v i f c xae dinh dnh hudng cua nhi&t d d d f n cdc t h d n g sd ddn nhdt cua m d hlnh Maxwell cdi t i f n dUdc phdn tieh ddnh gia trong ede hinh 9 , 1 0 vd 11,
Nhi&t dp Eo(MPal
5°C 3150
2 0 1 2900
35-C 2400
50 "C 2000
Bdng 3: Thdng sdE var^ cua cae nhdnh trong m d hlnh Maxwefl edi tien 10 nhanh.
N h i n h J T1{S) E|(5=C)
MPa Ej{20=Q
MPa E,(35=C)
MPa E, (SO°C)
MPa 1 5.10-'
550
546
585
600 2 - 29.10-' 270
336
365
370 3 168 lO-' 230
240
290
320 4 0,098
240
348
320
340 5 0.567
270
360
350
380
NhdnhJ t | ( s ) E,(S=C)
MPa E, { 2 0 ' ^ )
MPa E| (35°C)
MPa E) (50°C)
MPa 6 3.28 580
384
395
490 7 19,05
740
492
450
500 8
110,5 700
552
550
510 9 640,7
470
492
450
330 10 3 7 1 5
285
288
270
220
loglOM loglOM Hmh 8- So sanh giiia kit qui thf nghISm DMA (*) vrA mo hlnh 10 nhanh md phdng bing MatLab [nit Hln) vi bing chuang trinh f^HH Abaqus (u), dnhiSt dd 20«C.
Hmh 9' So sanh ket qua thi nghtem nin cd vdng lap tr! v^
ket qui md phdng bang Abaqus cho mau dnhiet do S°C. a •
rui •!«(•)
Hmh 10' So sanh ket qui thf nghi&m nln c6 vdng liptilvdf ket qui md phdng hSng Abaqus cho mau d nhiet dd 3S°C.Hinh 11: So sanh ket qui thinghi|m nin cd vdng l|pb*
vdi ket qui mo phdng bing Abaqus dio miu d nhiet dd 5CK.
vdi t h i n g h i f m n^n doe true vdi vdng lap t r f 'chdt tdi - chung Ung suat - gidm tdi - hoi phuc b i f n dang" duoc t i f n hanh d ba trudng hdp n h i f t d d 5<, SS'C, 50°C. Ket qua so sanh trong cdc trudng h c ^ nay cho thay sU t r i i n g khdf) hai dudng cong thuc nghi&m vd m d phdng.
4. K^T L U A N
Nghi&n cdu thuc nghi&m vd m d phdng sU dnh hudng cua n h i ^ t d d den dac tinh dan hdi nhdt ciia be t d n g d f o dUoc d f cap trong bdi bdo nay.
Phan tich ket qud thUc nghiem t r f n cdc thf n g h i f m k4o nen k&o nen dpc true vdi vdng lap tr^, vd t h i nghiem phdn tfch ddng DMA dupe sd dung. Ket qud phan tfeh thUe nghi&m cho t h f y tfnh Uu v i f t cda v i f c sd d u n g t h i n g h i f m DMA trong vi&c xdc dinh cdc t h d n g sd m d d u n ddn hdi vd ddn nhdt eiia vat lieu.
Su t u o n g d d n g gida k f t qud m d phdng bSng p h f n mem Abaqus cho t h i nghi&m n^n mSu tTnh vd d d n g vdi ket qud thue nghiem d cdc dieu ki&n nhiet dd khae nhau cho p h ^ p ddnh gla d p t i n cdy eiJa v i f c dp d u n g phuong phdp t h i n g h i f m DMA trong v i f c xdc djnh dnh hudng cua n h i f t d d d f n dac tinh ddn hdi nhdt ciia vdt lieu.
Till LlEU THAM KHAO
[1]. A. Dragon. Continuum damage mechanics applied to quasi-bnttle materials: Continuum damsge mechanics of matenals and structures. Editions, Olivier ALIIX and Francois Hild, 165-203,1002.
|2). J. Uazars. A descnption of micro- and macro scale damage of concrete stmcture Joumal of Engineering Structure Mechanics, 25(5/6), 729-737,1986
[3]. Le ITiet Dung. Modelisalion et Identification du componement plastique visco-elastique endommageible d'un mat^nau agrlgataire. Th^se de doctorant University Fran^ois- Rabelais de Tours, France, 2007.
|4] U 6ratton.V-DLe,A Ffachon,M.CaliezandD Plcan.
Mechanical behaviour of a vlsco-elastkplasticgranularmaterlal:
Expenmental procedure and modelling. WSEAS Transactions on Computers Issue 1, Vol S.pp 149-156, September 2006
[5] VletDungLe.M Gratton,M Caliez.A Frachon,D,PIcart, Experimental mechanical diaractenzation of plastic-bonded exploshfes. Joumal of Matenal Saence. 45,5802 - 5813,2010.
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