auxetic structures_subramani.pptx

7/26/2019 Auxetic structures_Subramani.pptx

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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

Poissons Ratio (v): -

Generally, materials possess positive Poissons 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 Poissons 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 Poissons 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

. 8ertical rod an"le &rt node

- !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< =>

?< r@ ;

23 ;@ r< B

@ r @ >

3 B r< ;B


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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

ex!i$its !i"! ne"ative Poissons ratio

(means structure !as !i"! transverse

expansion) and vice-versa

tructures tensile $e!aviou

upon its initial an"le 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 Poissons 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"


PoissonKs ratio

A ti $ ! i f difi d t t


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Auxetic $e!aviour of modified structure

>> ; B> =; ?>

-C

->B

->

->@

>>

ample > @> > :>

-C>

-B>

-:>

-@>

>>

Glass *i$re 4asalt *i$re

/ar$on *i$re


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 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



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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



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;lain griREA


>> >; @; > ; > ; ;>>>

>;

@;

>

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 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 Poissons 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

auxetic structures_subramani.pptx

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