Trao ddi hpc thugt & Thdng tin Khoa hpc Cong nghe
NGHIEN ClTU MO PHONG SlT PHAT TRIEN V£T NlTT TRONG BE TONG NHLTA CO XET D £ N TINH DINH K £ T VCH A B A Q U S
ThS. NGUYEN HCTU Q U O C HUNG Bg mdn Kji thu&t hg tdng dd thi Liin bd mdn Cong trinh -Casd 2 Tru&ng Dgi hgc Giao thdng Van tai TS. LE ANH T H A N G Khoa X&y dung vd Ccf hgc U'ng dung Tru&ng Dgi hgc Suphgm Ky thugt TP.HCM
Tdm tat: Md hinh nghien cuu md phdng su phdt trien vii ndi cd xet den tinh dinh kit cua vdt li^u dd vd dang dugc nghien cuu tren thi gidi V&i vdt lieu Id be tdng nhua trong nganh dudng thi viec nghien ciru vd dp dung md hinh ndy vdn cdn rdt nhieu hgn che. Bdi bdo irinh bcry tdng qudt vi md hinh phd hdy cua be long nhua cd xet den tinh dinh kil vd liin hdnh dp dgng md hinh di md phdng cho trudng hgp mgt dirdng bi tdng nhua chua xudt hien vet nut.
Qua dd, liin hdnh nhgn xet cdc kit qud mo phong duac. Kit qud md phdng cho thdy md hinh phdt trien vet ndi trong be tdng nhua cd xet den linh dinh kit cua vgt lieu nhua cd the thuc hien bdng phdn tu dinh cua phdn mem ABAQUS Md hinh ndy md phdng dugc tdc dgng cua nhiet dp den sg thay doi tinh dinh cua vdl lieu nhua
Abstract: The model that researches the simulation of the crack growth which is considered the cohesion is popularly researched all over the world today. However, the material is asphalt concreie in the road field, this research model is not widely studied. This paper generally give about cohesive zone model of asphalt concrete, based on these fundamentals lo conduct the simulation for the case of asphalt concrete's road surface that without having the cracking. Coincidenially, conducting brings out the conclusions of simulation model. The results of simulation consider that cohesive zone model of asphaU concrete can conduct by cohesive element of ABAQUS software. This model simulated the reaction of temperature to the change of asphalt concreie's cohesion.
l . D A T V A N D E
Be tdng nhua cd nhimg dgc tinh t u o n g ddi phiic tgp, Vgt lieu nhya ludn t h i hien rd tinh dinh thay doi theo nhift dg. Dgc tinh nay gSy i n h h u d n g dfn irng xCr va su phat trien ciia vet nirt.
Trong giai dogn nghien c u u hifn nay, anh h u d n g dinh ciia vat lifu nhya cdn it nhieu gSy khd khdn cho cac nha nghien ciru trong cdng tac md phdng sy phd buy ciia be tdng nhua. Nghien Cliu ve tinh dinh ciia vgt lifu nhya cdn nhieu han che, chi mdi d u g c tien hanh nghien ciiru tir nam 2006 cCia t r u d n g dai hgc Illinois. Trong dd Song va cdng s u da tien hanh thi nghifm thyc va so sanh ket quS vdi md phdng. Qua do, dng da de xudt cdc tham sd dSu vdo cho md hinh dinh cua bf tdng nhya.
Nghien c u u v l md hinh dinh cho be tdng nhua d Viet N a m cdn n h i l u hgn che, hau nhu chua cd nghien ciiu nao d u g c t i l n hdnh v l van d l nay. Bai bao nay la mdt nghien ciru b u d c ddu trong nd lyc md phdng su phdt triln v l t mil Irong be tdng nhua cd xet den tinh di'nh ciia vat lifu
1 4 4 Tgp chi K H O A H O C G I A O T H O N G V A N T A I S 6 4 4 - 1 2 / 2 0 1 3
Trao ddi hpc thugt & Thdng tin Khoa hpc Cdng nghe nhya. Ket qua nghien ciru the hifn budc ddu thanh cdng trong vifc md phdng vdi phan mIm thuang mgi ABAQUS v6.11.
2. TONG Q U A T V E M 6 HINH P H A HUV CO XET DEN T I N H DINH KET Viing phat trien vet nut cd xet din tinh dinh ciia vat lieu la vimg ma trong dd cac mSt dugc tach ra trong khi vSn tdn tgi gia trj lyc keo. Vlt mit phat triln tuan dieo moi quan hf giira chuyin vi va lyc keo trong vung dinh. cdn ggi Id viing dan hoi hogt dgng [2], [3], [4]. Hinh la minh hpa cho md hinh vimg phat trien vlt nut cd xet din tinh dinh kit. Hinh lb minh hga mdi lien hf giifa irng sudt va biin dang d vimg dinh ciia md hinh, cdn dugc ggi IS dudng cong o - 5.
Hinh 1. Md hinh tdng qudt phd hiry vdt li4u cd xet din tinh dinh kil: (a) thi hiin vimg dinh tgi ddu vet nut.
(b) the hien mdi liin h4 giiia dng sudt vd biin dgng keo d vimg dinh
Trong hinh lb, diem A the hifn mdi lien hf giira dng suSt dinh o va do md rgng khe nirt khi chua xuSt hifn vlt nut, diem C Id liic ma lyc dinh dat gia tri Idn nhdt. Dilm E the hifn tiic do md rgng vet nut dgt gia trj tdn nhSt, gia trj luc dinh bang khdng.
Hifn nay vSn chua cd phuang phdp chuSn xac ndo de xac djnh mui vet nirt tir dudng cong a - 5. Tuy nhien, chiing ta cd thi dl dang xdc djnh dugc vj tri cua ba dilm dgc biet, mgt la vj tri ma chuyin vj dgt den gia trj Smax va luc keo dat dugc gia trj lyc dinh eye hgn (dilm C tir dudng cong o - 5 hinh 1), hai Id vj tri ma chuyen vj dgt den gid tri 6sep va luc keo vira mdi trift tieu (diem E tir dudng cong o - 5, hinh I b. diem cudi cimg la vj tri ma vat lieu chua xuat hifn vet nut (dilm A noi ma 5 = 0') [8].
Vj tri ciia mui vet nut trong vimg phdt trien vet mil ed xet den tinh dinh ket khdng the xac djnh duy nhat, do dd phdi gia thiet them vi tri diem C d hinh la. Vdi gia thiet nay chiing ta cd the xac djnh dugc vimg chuyen tiep la vimg dgc theo chieu dai ciia vlt nirt tir diem A den diem C, vimg chuyen tiep cd chieu dai la tj va viing ddng dudi tir C den E cd chieu dai la I3. Tdc dg phat trien vet nirt dugc dugc tinh todn cdn cir vao nang lugng pha hiiy. Trong phuang phap sd, chung ta can xdc djnh vj tri ciia mui vlt nirt gia djnh dk dan gian hon cho vifc xac djnh ndng tugng va cdc tinh toan khac. Miii vlt nut gia djnh d dSy dugc ggi la mui vet nut dinh kit.
Tap chi KHOA H Q C GIAO THONG VAN TAI S6 44 - 12/2013 145
Trao ddi hpc thugt & Thdng tin Khoa hpc Cdng nghe 3. HINH DANG VA KICH THlTdC MO HINH
Cdn CUT vao dang phat trien vet mit phd biin trong ket cSu do dudng be tdng nhya, nhu the hien d hinh 2. Vet nut phat triln theo mode ! Id chinh.
Kich thudc ciia md hinh dugc chpn la 230mm dai, lOmm rgng vd chieu day la 1mm. Co sd lya chgn md hinh dugc cdn cu theo chieu cua ldp be tdng ciia dudng cao tdc tir 200 - 250mm, bai bSo chgn 230mm de md phdng. Hinh 3 the hifn kich thudc cua md hinh vd vi tri eiia phdn tudinh [1].
Cac thdng sd dSu vao cho md hinh tir thi nghifm tren mSu hinh trdn ggi tdt la DC(T) cua trudng dgi hgc Illinois - Hoa Ky. Cdc thdng sd dau vao cua md hinh dugc tdm tdt d bdng 1.
Chung bao gdm a, 5n,axi EBmhua. Gc* u Id hf sd mu ciia phuang trinh bieu dien, chuyen vi tdi hgn ciia phSn tii, module dan hdi cua mau, nang lugng phd huy, hf sd Poisson [4].
Bdng 1. Bang tdng hap cdc thong sd cho mo hinh md phong Hinh 2. Hinh minh hga cho phdt trien vet niH
Nhiet dp -loV -20°C -30°C
a 10 10 10
Sjnax (mm) 0,00113 0.00113 0.00113
EBTnlnia(GPa) 2.56 3.40 3.54
Oc(J/m') 410 204 163
u 0.35 0.35 0.35 4. KET QUA MO PHONG
Md hinh d hinh 3 dugc lap bang ABAQUS v6.I I. Hinh 4 the hifn each chia ludi phan tii, vi tri dat lyc va dieu kien bien. Md hinh cd mdt dau chiu lyc keo P va ddu cdn Igi dugc ngam chdt. T6ng sd phdn lir ciia md hinh la 768, vdi tdng so niil la 910. Kich thudc phan lii' dinh la 0.1mm[l], [5], [7].
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Hinh 3. Md hinh mo phong suphd huy be Idng nhua cd xet din tinh dinh kit
Hinh 4. Md hinh sau khi dugc khai bdo diiu kien bien vd CMOD
146 Tgp chi KHOA HQC GIAO THONG V^N TAI So 44 - 12/2013
Trao ddi hpc thugt & Thdng tin Khoa hoc Cdng nghe Ket qua dugc thi hien d hinh 5. Trong dd, CMOD IS chuyen vj md rdng mifng vlt nut (mm) cung la nai dat luc P.
CMOD(MM)
Hinh 5. Md hinh tdng hgp kil qud mdi quan he giira P vd CMOD a ba nhiit do -lO"C.-2(fC vd -3Cf'C Gia tri lyc P,nas d ba nhift do thay ddi tir 17.34N d -1 O^C va tdng ddn din 18.00N d -20"C vd 18.75N d -SO^C. 6 nhiet dg -30''C, nang luang pha huy IS be nhat (Gc = l63J/m-) va module dSn hdi cua mdu la Idn nhdt, gia trj P,^^^ van cd thi dgi gia trj Idn nhSt. Vgy cd thi ndi gia tri Pmax phy thudc vao ca module ddn hdi va nang lugng phd buy. Khi dat din biin dang tdi han, mSu bat dau gidm kha nang chiu lai. Biin dgng tdi han dat gia trj Idn nhat d nhiet dg -lO^C va giam dan d nhiet do -20''C va -30''C. Dilu nay la hgp ly khi nhiet do giam, vat lifu trd nen gidn han va se pha hogi khi chuyin vi be hon. Hinh 5 cung thi hifn kha nang dap ung ciia md hinh vdi sy thay ddi nhift dd [ i ]. Qua trinh phat iriln vlt nirt dugc thi hifn chi tilt qua hinh 6.
Hinh 6. Minh hpa cho qud trinh phdt triin vet nut dugc md phdng irong ABA QUS: (a) luc vit nut chua phdt trien. (b)-(e) the hien su phdt trien tir tir cua vit ndi
Tiln hanh so sanh ket qua md phdng vdi kit qud thyc nghifm tir dai hpc Illinois bdng cdch
Tgp chi KHOA HQC GIAO THONG VAN TAI S 6 4 4 - 12/2013 147
Trao ddi hpc thugt & Thdng tin Khoa hpc Cdng nghe
chuan hda cac gia trj: tryc OX la gia trj P/P,™, va tryc OV la gia trj CMOD/5,TOX nhu hinh 7 d ca banhietdg-10°C,-20''C,-3D"C [I].
CMODl&ia^
Hinh 7. So sdnh kit qud md phong vd kit qua thirc nghiem DC(T) ciia dgi hpc Illinois Hinh 7 thf hifn vung tu gid trj P = 0 den gia trj P = P,^^ cdc dudng cong gSn nhu triing nhau va ducmg cong a - 5 hoSn loan phii hgp vdi kel qud thyc nghiem ciia Song va vdi ly thuyet ctia md hinh nhu dd trinh bay d ben tren. Vifc md phdng sy phat triln vlt nut cua be tdng nhya cd xet din tinh dinh kit ciia vgt lifu nhya bdng ABAQUS da cho kit qud kha tdt [1].
4. KET LUAN
Md phdng sy phai triln vlt nirt trong be long nhya cd xet din tinh dinh ciia vgt lieu nhya da dugc thyc hien bSng ABAQUS vdi cac tham sd ciia md hinh cd dugc tir thi nghifm ciia trudng dgi hgc Illinois. Ket qua cd dugc the hifn su phii hgp giira ket qud md phdng tren ABAQUS va
• ly thuyet ciia md hinh. Ngoai ra. ket qud md phdng edn cho thdy md hinh cd the xet dirge dnh hudng cua nhift dg den tinh dinh ciia vat lifu nhya. Ddy la hudng nghien ciru mdi d Vift Nam hura h^n se cd nhieu nghien ciru tiep theo de bd sung hoan chinh cho md hinh phd biiy ciia be tdng nhya cd xet den tinh dinh ket.
Tdi lieu tham klijio
(I]. Nguyin Hflu Qudc Hiing. "Nghien ciru mo phong sy phdt irien vlt nirt trong be tong nhya co x6t din linh dinh kit", Ludn vdn thac sT, Dai hgc Bach khoa TP.HCM, 2013.
[2]. C Shet. N.Chandra. Analysis of Energy Balance When Using Cohesive Zone Models to Simulate Fracture Proccesses, Journal of Engineering Materials and Technology, vol. 124, pp. 441-450, Oct. 2002.
13]. SaeidMojiri. Numerical Analysis of Cohesive Crack Growth Using Extened Finite Element Method, M.A. thesis, Institut de Recherche en Genie Civil et Mechanique (GeM), France, 2010.
[4], Seong Hyeok Song. Fracture of Asphalt Concrete: a Cohesive Zone Modeling Approach Considering Viscoelastic Effects. Ph.D. thesis, Univesily of Illinois, USA, 2006.
[51 ABAQUS. User's manual version 6.11. Hibitt. Karlsson vd Sorenson Inc. Pawtucket, R.I, 2012.
[6]. T.LAderson. Fracture machanics: fundamentals and applications. CRC Press. Boca Raton. Florida, 1995.
[7] K Ho-Le. "Finite element mesh generation methods: a review and classification," Locked bag No. 9, Australia, 1988.
[8]. E.A. Bonifa. Cohesive zone modelling to predict failure proccesses. Canadian Joumal on Mechanical Sciences & Engineering, vol. 2, No 3, pp. 42-54, Mar. 2011 •
Phan bi£n: PGS. TS. Bui Trong Cau
Tgp chi KHOA HQC GIAO THONG VAN TAI So 44 - 12/2013
