1/10AUXETIC MATERIALS2/10Overview IntroductionMechanism, Structure and Functions of materiasMechanica !ro!erties A!!ications 3/10Introduction "Au#etics$comesfromthe%ree&wordau#etos,meanin'"thatma()e increased$*Some materias or structures e#!and atera( when stretched or contract in thetransversedirectionunderunia#iacom!ression*Thesemateriasare said to have ne'ative +oisson,s ratio -.+R/Lar'e 0scae ceuar structures with .+R !ro!ert( were first reaised in 1234 in the form of two dimensiona siicone ru))er or auminum hone(com)s*La&es first deveo!ed the .+R !o(urethane foam with re0entrant structures* This !o(meric foam has a +oisson,s ratio of 05*6*.atura(occurrin'7roc&,mineras*Manmade7metaicfoams,micro!orus !o(mers, car)on fi)re aminates*Enhanced mechanica !ro!erties such as enhanced shear moduus, fracture tou'hness and indentation resistance*4/10Mechanism, Structure and Functions of materias+oisson,s ratio 8 transverse strain9 on'itudina strain*+oisson,s ratio is in the ran'e of : 1 ; < = 5*> *A networ& i&e structure can )e )uit u! consistin' of rectan'uar nodues connected )( fi)ris* 5/10Mechanism, Structure and Function of materiasConventiona Foam Au#etic Foam Conventiona hone(com) Au#etic hone(com) 6/10+ro!erties of materias?i'her resistance to shear strain, caused )( twistin' or tearin' forces* ?i'her indentation resistanceE 8 4 % - 1 @ < / 8 A B - 1 : 4 < / *7/10+ro!erties of materiasCeformation )ehaviourStress0 strain reationshi!s for conventiona and re0entrant foams* Initia reativedensit(7 5*53* D Soid s(m)os7 anneaed* O!en s(m)os7 not anneaed* E SFuares7conventiona foam, voumetric com!ression 1* G Trian'es7 re0entrant foam, voumetriccom!ression 4*5* O Circes7 re0entrant foam, voumetric com!ression 4*>* H Ciamonds7 re0entrant foam, voumetric com!ression A*5 -after Choi I a&es, 1224/8/10+ro!erties of materiasConventiona and au#etic foams fai in a )ritte manner* Fracture wi ha!!en in two wa(sThe fracture tou'hness of Au#etic foams are 1*J 01*6 times 'reater than conventiona foams*The( have hi'her crac& resistance com!ared to conventiona materias 9/10A!!ications Sensors0 desi'n of h(dro!honesKio0 medicineAu#etic reinforced fi)re com!ositesA!!ications 10/10LKod( armors, Kuet !roof ?emets and )uetsKast resistant structuresThan& (ou