auxetic materials-nano to macro

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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

     

     

    *

    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

    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