Tes and mesoscopic ini e elemen analysis on mechanical p ope ies deg ada ion o aged coa ed ab ics
VIII In e na ional Con e ence on Tex ile Composi es and In la able S uc u es
STRUCTURAL MEMBRANES 2017
Qilin Zhang, Yun ing Li
TEST AND MESOSCOPIC FINITE ELEMENT ANALYSIS ON
MECHANICAL PROPERTIES DEGRADATION OF AGED COATED FABRICS
STRUCTURAL MEMBRANES 2017
QILIN ZHANG*, YUNTING LI†
*College o Ci il Enginee ing
Tongji Uni e si y
200092 Shanghai, China.
E-mail: zhangqilin@ ongji.edu.cn
† College o Ci il Enginee ing
Tongji Uni e si y
200092 Shanghai, China.
E-mail: liyun ing[email p o ec ed]m
Key wo ds: PVDF-coa ed Fab ics, Ageing Beha io , Mechanical P ope y, Mesoscopic
Fini e Elemen Analysis.
Summa y. In his pape he mechanical p ope ies deg ada ion o aged coa ed ab ics is
in es iga ed. Tes s on he ension s eng h and he ea ing s eng h o he aged ab ics a e
ca ied ou , which is om he memb ane oo o Qingdao S adium used o mo e han 13
yea s. The s eng h deg ada ion deg ees o he aged ab ics a e ob ained. Due o he
con igu a ion o ab ics he nume ical simula ion on i s s ess s a e as well as i s ac u e
p ocess and mechanism is e y di icul . In his pape , a mesoscopic ini e elemen model o
plain wo en ab ics s ess analysis is es ablished based on wo en con igu a ion ab ic cells.
The nume ical analysis shows ha a i m ya n-ya n connec ion a in e lacing poin would
make ab ics has high shea s i ness and concen a es ensile s ess on he edge o he ab ics
in which applied load. I coincides wi h he bi-axial ensile es , in which c uci o m specimen
ac u e always a he a ms ins ead o co e a ea. Finally he ac u e c i e ion is buil up o
new and aged ab ics on he basis o he es and analysis esul s o his pape .
1 INTRODUCTION
Memb ane s uc u e, wi h many ad an ages including a ligh weigh , good ligh
ansmission, lexible s e ch, s ong sense o shape and g ea a chi ec u al pe o mance, is
well ecei ed and has been widely used in public shel e s uc u es. Buil on a bend in he
Ri e Thames in G eenwich, London, he Millennium Dome is one o he mos amous
B i ain's landma ks. The wo ld's mos luxu ious Uni ed A ab Emi a es Bu jAl-A ab ho el in
Dubai is a double-laye memb ane s uc u e o he building. I is buil on a man-made island
wi h a ligh g ace ul sailboa s yling shape and in eg a ed in o he su ounding landscape.
Besides, he memb ane s uc u es a e p e e ed in he many public buildings, such as S adium
and Ai po . Howe e , he memb ane s uc u e also has essen ial sho coming, ha is,
compa ed wi h he s eel, conc e e, glass and o he building ma e ial, memb ane ma e ial is
mo e easily aging and could cause he des uc ion o he s uc u e. To ensu e sa e y, aging o
125
Qilin Zhang, Yun ing Li
2
memb ane ma e ials is an impo an subjec .
Many esea ch on he e ec s o di e en ac o s on he aging o memb ane ma e ials ha e
been ca ied ou wi h a i icial accele a ed ageing me hod [1-8] o ou doo ageing me hod[9-12].
These s udies a e he basis o he s udy o aging p ope ies o memb ane ma e ials. Fo
u he unde s anding o ma e ial aging, he aging coa ed ab ics emo ed om a s adium
been selec ed as esea ch objec s, a lis o mechanical es s a e ca ied ou . To igu e ou i s
aging mechanism, nume ical simula ions a e also pe o med. This pape consis s o wo main
pa s, expe imen s udy and nume ical analysis.
2 AGING PROPERTIES OF PVDF
To e alua e he du abili y o coa ed ab ics a e aging in a s uc u e ou doo , a se ies o
con as expe imen s was ca ies ou be ween he na u al ageing coa ed ab ics emo ed om
a s adium buil in 2007 and he new specimens o he same ype o coa ed ab ics. Mechanical
p ope ies o coa ed ab ics, including ensile, ea ing and bonding s eng h, a e es ed
acco ding o DG/T J082019-2007 (2007)[13]. The main es esul s and analysis a e as ollows
[14].
2.1 Coa ing
The educ ion o b igh ness a he sunny side is 56.42%, while ha a he shaded side is
30%. Acco ding o he mic oscopic mo phology o he ab ic coa ings (Fig. 1), he ageing
coa ing a he shaded side has some bulges, bu he e is no c ack and pul e iza ion. Howe e ,
he ageing coa ing a he sunny side is ull o c acks, wi h bulges and pul e iza ion. The colo
change and c acks caused by ageing a he sunny side is mo e se e e han ha a he shaded
side. Acco ding o he aging p inciple o polyme s，i is mainly due o he ageing mechanism
o high polyme ma e ial, namely up u e o molecula chain (deg ada ion) and c osslinking
o mac omolecula chain [15].
126
Qilin Zhang, Yun ing Li
3
Figu e 1: Pho og aphs o he coa ing by SEM: (a) new coa ing×500 (b) ageing coa ing a he shaded side×500
(c) ageing coa ing a he sunny side ×500 (d) new coa ing×10000 (e) ageing coa ing a he shaded side×10000
( ) ageing coa ing a he sunny side ×10000
2.2 Fo ce a ailu e & ea ing s eng h
The esul s o o ce a ailu e and ea ing s eng h es s a e p esen ed in Table 1. In wa p
di ec ion, o ce a ailu e o he new ab ics is 8132 N/5 cm, while ha o he ageing is 7329
N/5 cm. In we di ec ion, o ce a ailu e o he new ab ics is 7051 N/5 cm and ha o he
ageing one is 6792 N/5 cm. Tes esul s show he o ce a ailu e o ab ics dec eases by 9.9%
in wa p di ec ion and dec eases by 3.7%in we di ec ion. In wa p di ec ion, ea ing s eng h
o he new coa ed ab ics is 1217 N, while ha o he ageing is 937 N. In we di ec ion,
ea ing s eng h o he new coa ed ab ics is 1163 N and ha o he ageing is 818 N.
Expe imen al esul s show ha ea ing s eng h o aging coa ed ab ics dec eases by 23% in
wa p di ec ion and 29.6% in we di ec ion. Possibili y P o signi ican di e ence a e 1.5E-18
and 2.8E-29 in wa p and we espec i ely, which a e lowe han 0.05. T- es p o es ha
ea ing s eng h o he new and aging ma e ial has no able di e ence in wa p and we
di ec ions. In addi ion, i can be ound ha he deg ada ion o ea ing s eng h is mo e ob ious
han ha o o ce a ailu e, which is consis en wi h o he esea ches [4, 8, 24].
Table 1: Fo ce a ailu e es ing esul s
Ma e ial Tensile o ce (N/5cm) Tea ing s eng h (N)
Wa p We Wa p We
New 8132 7051 1217 1163
Ageing 7329 6792 937 818
Reduc ion 9.9% 3.7% 23.0% 29.6%
3 NUMERICAL ANALYSIS
In o de o analyse s ess o aging memb ane ma e ial. The nume ical model o coa ed
ab ics is buil . The e a e h ee pa s in his sec ion. S ess cha ac e is ics o he coa ed ya n
we e analysed and angen ial ac ion a he in e laced poin o ab ics was discussed. Besides,
he e ec o coa ing ha dening on ab ic was s udied.
127
Qilin Zhang, Yun ing Li
4
3.1 Me hod
Coa ed ab ics memb ane can be analyzed on h ee scales: mac oscopic, mesoscopic and
mic oscopic. In his pape , modelling and analysis a e on he mesoscopic. A ya n is he basic
cons i uen ma e ial.
Modelling ool is Texgen which [16, 17] is de eloped by he Polyme Composi es G oup a
he Uni e si y o No ingham as a modelling p e-p ocesso o a a ie y o applica ions
including solid mechanics. I p o ide a g aphical use in e ace o de ine pa h, sec ion shapes
and dimensions o a ya n and disc e ize ya ns by a buil -in mesh gene a o .
In his pape , wo we ya ns and wo wa p ya ns a e in e laced e ically o o m a uni
cell as ig. 2 shown. In Texgen, ya n pa h is ep esen ed by a spline S(u). As ig. 3 shown, 9
con ol poin s a e de ined and Na u al cubic spline is selec ed. Sec ion shape o ya ns a e
len icula acco ding o SEM abo e. Wid h and heigh is 1.8 and 0.4 espec i ely. O he
pa ame e s a e shown in he Table 2. Geome ic in o ma ion is acco ding o SEM o he ya n.
Figu e 2: Uni cell Figu e 3: Ya n pa h and con ol poin s
Figu e 4: The c oss sec ion o ageing coa ed ab ic
128
Qilin Zhang, Yun ing Li
5
Table 2: Pa ame e s o ya ns
Pa ame e s Wa p We
Ya n linea densi y
0.0002002 kg/m
0.00011 kg/m
Fibe densi y 1.37g/cm
3
1.37g/cm
3
To al ibe a ea 0.146554mm
2
0.08052 mm
2
Fibe diame e 25μm 25μm
Fibe pe ya n 300 165
Mechanical model o ya ns a e de ined in Abaqus [18]. Tensile p ope ies a e de ined using
expe imen al da a as iso opic hype elas ic ma e ials. The s ess-s ain cu es a e shown in
Figu e 5. The Poisson's a io is 0.4. The coa ing is de ined as elas ic ma e ial.
Figu e 5: S ess-s ain cu es o ya ns
3.2 Resul s and analysis
In he coa ing p ocess o he ab ic, he e may be wo modes o ac ion in he in e sec ion
o wa p and we ya ns. The i s si ua ion is ha wa p and we ya ns is bonded a he
in e lace poin s. The second is he coa ing ma e ial is no pene a ed inside and he e is only
angen ial ic ion a he in e lace poin s. In his pape , he s ess s a e o he ya n unde
ension in abo e wo cases is compa ed and analysed.
F om ig. 6-a, in he bonding mode, s ess o he whole ya ns a e mo e concen a ed a
some loca ion, while i is uni o m in he ic ion-mode. In he bonding mode, he maximum
and minimum alues di e by 1/3, howe e , s ess a e kep a he same le el in he ic ion
mode. Acco ding abo e, when he ya ns a e independen a he in e lace poin , he ab ics
would show a g ea e s eng h due o a easonable s ess dis ibu ion. A e applied coa ing, i
ya ns o he ab ics bonding oge he , he s ess o ya ns concen a ed in he ee a ea be ween
he in e lace poin s and i eaches o he maximum a bo h ends o he len icula sec ion.
129

Qilin Zhang, Yun ing Li
6
(a) Bonding oge he a in e lace poin (b) F ic ion model a in e lace poin
Figu e 6: S ess nephog am o wo models
Conside ing he modulus o elas ici y changes when he coa ing is aged, he ollowing
sec ions compa e he e ec o he coa ing ha dening on he in e nal s ess o he ab ic.
Wi h wo di e en elas ic modulus o coa ing, s ess o ya ns in a uni cell a e shown in
Figu e 7. In Figu e 7-a, when elas ic modulus o coa ing E is 15 MPa, he s ess concen a e
on he edge o a ya n. F om Figu e 7-b, when elas ic modulus o coa ing E is 150 MPa, he e
is a e age dis ibu ion s ess in a ya n. In addi ion, s ess a e con as ed a h ee ypical
posi ions o a ya n, as Figu e 8 shown. Unde he same load, s ess-s ain cu es o h ee
poin s on a ya n was show in Figu e 9. F om Figu e 9-a, i is easy o ind ha he e is a g ea
di e ence a h ee poin s. Howe e , in Figu e 9-a, s ess in he h ee posi ions is much close .
Ha dening o he coa ing end o a mo e equal dis ibu ions o s ess. The imp o emen o
s ess concen a ion can make he ya n o ce mo e uni o m and he ab ic s eng h highe
I should be emphasized ha he elas ic modulus o he coa ing discussed abo e is much
smalle han ha o he ya n. I he modulus o coa ing and ya n on he same le el, i will
cause s ess concen a ion in he coa ing and he bonding posi ion, and he o ce condi ion
needs a u he s udies.
(a) Elas ic modulus o coa ing E=15 MPa (b) Elas ic modulus o coa ing E=150 MPa
Figu e 7: S ess o wo models
130
Qilin Zhang, Yun ing Li
7
(a) Poin 1 (b) Poin 2 & a. Poin 3
Figu e 8: Typical posi ion
(a) Elas ic modulus o coa ing E=15MPa (b) Elas ic modulus o coa ing E=150 MPa
Figu e 9: S ess-s ain cu e
4 CONCLUSIONS
Based on he abo e esea ch, he ollowing conclusions a e ob ained:
- Aging coa ing has c acks, powde and o he aging cha ac e is ics.
- Tensile s eng h o coa ed ab ics dec ease by less han 10% and ea ing s eng h
dec eased o 20%~30%
- Nume ical analysis shows ha angen ial ac ion a he in e laced poin o ab ics
g ea ly a ec he dis ibu ion o s ess. When he wa p and we a e bonded a he
in e lace poin s, s ess is concen a ed on he edge o a ya n. I he e is only ic ion
in angen ial a he in e lace poin s, s ess dis ibu ion o a ya n is mo e e en.
- A e aging, he ha dening o he coa ing will lead o a mo e uni o m s ess
dis ibu ion o he ya n. This may be one o he easons why he ensile s eng h o
he ab ic does no dec ease signi ican ly a e aging
REFERENCES
[1] Zhang YY. E ec o Tempe a u e and Wa e Imme sion on he Mechanical P ope ies o
131
Qilin Zhang, Yun ing Li
8
Coa ed Fab ics. Ad anced Ma e ials Resea ch. Vols.129-131(2010): 230-234.
[2] Real L P, Ga de e J. Ageing and cha ac e isa ion o PVC-based compounds u ilised o
ex e io applica ions in he building cons uc ion ield 1: The mal ageing. Polyme
Tes ing. 2001, 20(7): 779-787.
[3] Be dahl P, Akba i H, Le inson R, e al. Wea he ing o oo ing ma e ials – An o e iew.
Cons uc ion and Building Ma e ials. 2008, 22(4): 423-433.
[4] Razak H A, Chua C S, Toyoda H. Wea he abili y o coa ed ab ics as oo ing ma e ial in
opical en i onmen . Building and En i onmen . 2004, 39(1): 87-92.
[5] Chen ZR, Zhang QL, Xue WL. Expe imen al Resea ch on Mechanical P ope ies o PVC
Memb ane a e Ageing. P oceedings o in e na ional Associa ion o Shell and Spa ial
S uc u es, W oclaw, Poland, 2013.
[6] Kuai BL. Aging Tes s o PVC Memb ane Ma e ial. Tensine ins anbul Symposium, 2013
[7] T iki E, A ie a C, Boukehili H, e al. Tea beha io o polyes e -based coa ed ex iles
a e he mo-oxida i e aging. Polyme Composi es. 2012, 33(6): 1007-1017.
[8] Andelko O, Ha amina T. E ec o aging on mechanical p ope ies o polyme ic ips op
ab ics. J. Polym. 2012.
[9] Joneydi S, Khoddami A, Zadhoush A. No el supe hyd ophobic op coa ing on su ace
modi ied PVC-coa ed ab ic. P og ess in O ganic Coa ings. 2013, 76(5): 821-826.
[10] Zhou S, Ding X, Wu L. Fab ica ion o ambien -cu able supe hyd ophobic
luo opolysiloxane/TiO2 nanocomposi e coa ings wi h good mechanical p ope ies and
du abili y. P og ess in O ganic Coa ings. 2013, 76(4): 563-570.
[11] Ahmed H. Imp o ing UV Resis ance o High Pe o mance Fibe s. P oQues Disse a ion
and Theses, No h Ca olina S a e Uni e si y, Raleigh, NC, 2011.
[12] Amb oziak A. Mechanical p ope ies o PVDF-coa ed ab ic unde ensile es s. J.Polym.
Eng. 2015; 35(4): 377-390.
[13] DGTJ08－2019－2007. Technical Speci ica ion o Inspec ion o Memb ane S uc u es.
Shanghai Cons uc ion and T a ic Commi ee: Shanghai, 2007.
[14] Li YT, Liu T, Yang B, e al. E ec s o Na u al Ageing on Mechanical P ope ies o
PVDF-Coa ed Fab ics. S uc u al Enginee ing In e na ional. 2016, 26(4): 348-356.
[15] Wen JB. Mechanical enginee ing ma e ials. Machine y Indus y P ess, 2009: 302.
[16] Long. H L L B. Modelling and simula ing ex ile s uc u es using TexGen. 2011.
[17] Lin H, Cli o d M J, Long A C, e al. A ini e elemen app oach o he modelling o
ab ic mechanics and i s applica ion o i ual ab ic design and es ing. 2012.
[18] Al. H L X Z. Au oma ed geome ic modeling o ex ile s uc u es. Tex ile Resea ch
Jou nal. 2012.
132