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Development of Composite Auxetic Stru
for Civil Engineering Applications
P. SUBRAMANI
PhD, Centre for Textile Sci. & Tech.
Scientic Guidnce
Prof. Raul FangueiroProf. Daniel Oliveira
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Introduction of Auxetic Materials
• Poisson’s Ratio (v): -
• Generally, materials possess positive Poisson’s ratio, ie stretc!in" expe
material t!inner and compressin" results in $ul"e• Auxetic materials $e!ave %ust reverse ie $ecome &ider &!en stretc!ed
&!en compressed, t!at is, t!ey possess ne"ative Poisson’s ratio
•
Reference: Liu Y and Hu H. Scientic Research and Essays Vol. 5 (10) !!. 105"#10$% 1& '
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Auxetic Materials Across t!e 'en"t! ca
• !e auxetic materials and structures (man-made and natural) !ave s!o&n i
*i"ure s!o&s t!at metals, cer
and composites no& exist in
it span all t!e ma%or classes o
Auxetic materials !ave enorm
many practical and tec!nolo
applications
Reference: lderson and Eans *E. d. 'ater. "000 1" +o. , !!. $1-
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• !e +e"ative Poisson’s ratio of auxetic materials ex!i$it a series of fascinat
properties compared &it! conventional materials,
Increased s!ear modulus
i"!er indentation resistance
i"!er fracture tou"!ness
Good ener"y a$sorption
Porositypermea$ility variation &it! strain
ynclastic curvature
Properties of Auxetic Materials
Conventional mate
Ref: Liu Y and Hu H. Scientic Research and Essays Vol. 5 (10) !!.
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Auxetic tructures
a b c d
e f
a . Re-entrant !oneyco
$ . /!iral !oneycom$
c .tar s!aped !oney c
d . 0ou$le arro& !ead
e 1 f . Missin" ri$
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2$%ectives
• 0evelopment of auxetic structures from fi$er reinforced $raided composi
• o study tensile and auxetic $e!aviour of developed auxetic structures
• 2ptimi3ation t!e developed structures $y studyin" t!e effect of struct
parameters so t!at developed structures &ill $e suita$le for civil applicati
• 0evelopment of analytical and numerical modellin" to study t!e au
$e!aviour of t!e developed auxetic structures
• Performance study of auxetic structures reinforced structural eleme
masonry) under tensile and flexural loads
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*i$er Reinforced 4raided tructure
• 5!at is 4raid6
– 4raid is a complex structure or patte
intert&inin" t!ree or more strands of flesuc! as textile fi$ers, &ire or !air
– In practical terms, $raid refers to a fam
continuously &oven on t!e $ias
– 4raidin" tec!ni7ue normally used for ropes
also interestin" for composite reinforceme
properties li#e in-plane multi-axiaconforma$ility, excellent dama"e tolerance
Reference: h/adi et al. eRESS oly/er Letters Vol.% +o.,
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0evelopment of structures: preliminary &or#
r2 ζ
Φ . 8ertical rod an"le &rt node
ζ - !e an"le formed $et&een vertical
and !ori3ontal rods at t!e node
- 8ertical rod ri$ len"t!
- ori3ontal rod ri$ len"t!
9 . !e an"le formed at t!e $endin" of
!ori3ontal rods
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tructural parameters
Structure AngleValue
(degree)Rib
Value
(cm)
13 ; r < =>
ζ ?< r @ ;
23 ;@ r < B
ζ @ r @ >
3 B r < ;B
ζ
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!e auxetic $e!aviour of t!e structures &ere evaluated $y ima"e-$ased
and results are reported !ere
Evaluation of auxetic behaviour
• Parameters of P!oto-mec!anical set-up
– peed of tensile testin" @; mmmin
– Ac7uisition fre7uency 3
– 'ens D +i##on * ;> mm
– 5or#in" distance @=;; mm
– !utter time
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Auxetic and tensile $e!aviour
• tructures &it! !i"! initial an"le φ
ex!i$its !i"! ne"ative Poisson’s ratio
(means structure !as !i"! transverse
expansion) and vice-versa
• tructures tensile $e!aviou
upon its initial an"le φ i"
s!o&s !i"!er tensile load an
and vice-versa
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2ptimi3ed structure
StructureCore
fiber t#pe
Core fiber$
texAngle %$
S 1 Glass @>> BB
S 1 Glass C>> BB
S 1 Glass B>>> BB
S 1 Glass ?B>> BB
S 1 Glass C>> =@
S 1 Glass C>> =C
S 1 4asalt C>> BB
S 1 /ar$on C>> BB
S 2 Glass C>> BB
S Glass C>> =C
+ote: E – @ and – consists $ot! un
lon"itudinal rods
*i"ure (a) sc!ematic dia"ram of $asic structu
ma"nified portion of structure, (d) sc!ematic
desi"n of missin" ri$, (e) structure @, and (f) struc
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Fvaluation of strain components and Poisson’s rat• /ross-!ead speed of tensile test
@; mmmin
• o measure dimensional c!an"es
durin" tensile load, a ima"e-$ase&as used
• 5it! suita$le p!oto-mec!anical
&as captured continuously t!
testin"
• 'ater t!e ima"es analy3ed in Im
calculate lateral strain and lo
values of t!e structures
*ormula used
, , -
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tructure defor
sta"es of t
r
F
*
Structure 1
Structure 2
Fff t f t ti $ ! i
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Fffect of parameters on auxetic $e!aviour
> < @ : ; B = C ?
->
Glass fi$re
4asalt fi$re
/ar$on fi$re
'on"itudinal strain HIJ
PoissonKs ratio
> < @ : ; B
-@;
-@>
-;
>>
'on"itudinal strain
PoissonKs ratio
> < @ : ; B = C ?
-:>
-@
-@:
-C
>>
An"le BB de"
An"le =@ de"
An"le =C de"
'on"itudinal strain HIJ
PoissonKs ratio
A ti $ ! i f difi d t t
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Auxetic $e!aviour of modified structure
>> ; B> =; ?>
-C
->B
->
->@
>>
ample <
ample @
ample
'on"itudinal strain HJ
PoissonKs ratio
->= >> >=
-@;
-@>
-;
>>
'on"itudinal strain HI
PoissonKs ratio
il $ ! i f ti t t
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ensile $e!aviour of auxetic structures
Structure*iber
t#pe+ex
Angle
%$ &
Avg, max,
tensile load$
-.
Avg, elongation
at max, tensile
load$ /
Avg, 0or-
of rupture$
S 1 Glass @>> BB @ (B) > (> BB ? (>> BB ;? (;) ?< (@@) ?@ (;>)
S 1 Glass C>> =@ ;< ()
S 1 Glass C>> =C B? (> BB B< ( (=?) CC (B @ :
>
<
@
:
;
B
=
Fl
)ensile 'oad H#+J
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Re-entrant !exa"on or 4o&-tie desi"n
@0 Re-entrant !oneycom$ structure
from !exa"on
Basic re-entrant
hexagonauxetic esi n
!oi"e re-entrant
hexagonauxetic esi n
• a, c
ri$
• b .
ri$
• L .
!or
dia
0 l d t t d t! i t
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0eveloped structures and t!eir parameters
Structure 1 Structure 2 Structure
StructureCore
fibers
Core fiber linear
densit#$ texAn
1
Glass
4asalt
/ar$on
@>>, C>>, B>>>
C>>
C>>
θ
2
Glass
C>>
θ
Glass C>> θ
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Structu
tructu
(ymmet ry
line
F
tructure deformation a
tensile loadin"
Structure 1
tructure @
*
Fffect of parameters on auxetic $e!aviou
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Fffect of parameters on auxetic $e!aviou
>> @> > :>
-C>
-B>
-:>
-@>
>>
Glass *i$re 4asalt *i$re
/ar$on *i$re
'on"itudinal strain HIJ
PoissonKs ratio
3,3 1,3 2,3
45,3
46,"
47,3
4!,"
4,3
41,"
3,3
2!33
7333
ongitudinal strain 9
;oisson < @ : ;
-;
-:
-
-@
-<
>
(ample < (ample @
'on"itudinal (train HIJ
PoissonKs ratio
3,3 3, 3,7 3,5
47,3
4!,8
4,7
42,!
41,2
3,3
S
S
ongitudinal strain
;oisson
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ensile $e!aviour of auxetic structures
> @ >
@
:
B
C
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Auxetic Structure! Reinfor
Structurl "le#ent!
t t i f d t
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tructures reinforced mortar
/omposite "rid
used as
reinforcement in t!e
clamp area
Acryl
sample
tructure R* mortar: B>> x x
ensile testin" of structures reinforced mor
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ensile testin" of structures reinforced mor
• ensile test carried out usin" niversal tensil
mac!ine
• !e speed of t!e tensile test &as #ept as >; m
• o avoid crac# in t!e sample durin" sample f
mac!ine, ne& $ottom clamp &as desi"ned an
ensile testin" of structures reinforced mor
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ensile testin" of structures reinforced mor
P la in Gr id R* ) RM 4a sic 'G R * ) RM
M odified'GBBR*)RM M odified'G=C R*)RM
Flon"ation HIJ
)ensile 'oadH#+J
o>enge grid or =issing rib structures
R* =ortar
;lain ?rid ? @asic ? =o
ensile testin" of structures reinforced mor
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;lain griREA
ensile testin" of structures reinforced mor
>> >; @; > ; > ; ;>>>
>;
@;
>
Plain Grid RM
4asic 0esi"n RM
train HJ
ensile stress HMPaJ
Auxetic structures reinforced masonry &all spe
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Auxetic structures reinforced masonry &all spe
c!ematic of masonry sample 4ric# dimensionAuxetic structures use
Masonry &all &o any reinforcement Masonry &all durin" reinforcement Masonry &all after rein
*lexural testin" of masonry &all
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*lexural testin" of masonry &all
=iddle
eft
Rig't
*ront
@ac-
• est tandard: F+ ;@-@:
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> B ?
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>> >: >C >
@>
:>
B>
C>
>(ample <
0isplacement HmmJ
*lexural load H#+J
S, .o, Specimen description *lexural stre
1 +on-reinforcement >BC
2 'o3en"e "rid R*
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*ailure and crac# $e!aviour masonry specim
Conclusions
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Conclusions• Auxetic structures &ere produced usin" core fi$re reinforced $raided compo
on missin" ri$ and re-entrant !exa"on desi"n
• Auxetic and tensile $e!aviour of t!e structures &ere studied $y varyin" t!ei
materials parameters• /ompared to material parameters, structural parameters s!o& si"nifican
tensile and auxetic $e!aviours
• Analytical modellin" &ere derived to predict t!e Poisson’s ratio of t!e deve
and it s!o&s $etter correlation &it! experimental results
•
+umerical modellin" usin" 0IA+A &as developed to study t!e tensile and $e!aviour of t!e structures and results s!o&ed $etter correlation &it! exper
• *lexural testin" auxetic structures reinforced masonry s!o&ed !i"! ductility
ener"y a$sorption t!an commercial "rid desi"n
*uture or-
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*uture or- • !e surface of $raided rods (ie contour of $raided rod surface) can $e altere
ad!esion &it! masonry elements
• 0evelopment of analytical modellin" to study tensile $e!aviour of develope
structures $ased on missin" ri$ or re-entrant !exa"on desi"n
• auxetic structures can $e used as reinforcement to t!e masonry and study t!e
under impact load
• 0evelopment of auxetic composite and use as stren"t!enin" material of civil
elements and study t!eir performance under impact, flexural loadin", etc
• 0evelop auxetic structure reinforced sand&ic! panel and auxetic #nitted com
advanced tec!nical fi$res and use as stren"t!enin" materials for civil structu
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+'an- Bou