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(January 1981) pp 71-78T h e p u r p o s e o f th i s p a p e r i s t o s h o wt h a t t h e e q u a t i o n s o f th r e e - d i m e n s i o n a lani s t ropic e l a s t i c i ty can be spl i t i n tot w o i n d e p e n d e n t s y s t e m s a n d t h a t t h i sp r oc udur e , w h i c h i s pos s i b l e f o r i s o -t r op i c m a t e r i a l s , m a y be c a r r i e d ove r t ot he a n i s o t r op i c p l a t e .A m e t h o d f o r d e t e r m i n i n g t h e m o d e 1d e l a m i n a t i o n f r a c t u r e t o u g h n e s s o f e l a s -t i c a n d v i s c o e l a s t i c c o m p o s i t e m a t e r i a l sD e v i t t, D . F . , S c h a p e r y , R . A . a n d B r a d -l e y W . L . J o u rn a l o f C o m p o s i t e M a te r -ia l s V o l 1 4 (O c to b e r 1 9 8 0 )p p 2 7 0 -2 8 5A s i m p l e a p p r o a c h t o t h e d e t e r m i n a -t i o n o f d e l a m i n a t i o n f r a c t u re t o u g h n e s si n t h e o p e n i n g m o d e h a s b e e n d e v -e l ope d u s i ng a s p l i t be a m a nd a non -l i ne a r a na l y s i s . T he a na l y s i s ha s be e nc o n f i r m e d w i t h e x p e r i m e n t a l m e a s -u r e m e n t s on g l a s s / e poxy s ys t e m s u s i ngs pe c i m e ns o f t h r e e t h i c kne s s e s, t e s t e do v e r a w i d e r a n g e o f c r a c k g r o w t hr a te s . T h e m e a s u r e d r a n g e o f e n e r g yr e l e a se r a t e s o f 525 - 100 0 N m -~ f o r t her a nge o f c ra c k g r ow t h r a t e s s t ud i e d i ss how n t o be c ons i s t e n t w i t h p r e d i c t i onsf r om a n i de a l i z e d v i s c oe l a s t i c c r a c kg r o w t h t h e o r y a n d v i s c o e l a s t i cb e h a v i o u r o f t h e r e s in a s d e t e r m i n e df r o m c r e e p / r e c o v e r y t e s ts .N o n l i n e a r v i s c o e l a s t i c b e h a v i o u r o fp o l y p r o p y l e n e a n d g l a s s r e i n f o r c e dp o l y p r o p y l e n e i n c r e e pG u p t a , V i d y a B h u s h a n , a n d L a h i ri ,J h u m u r Journa l o f Composi te Materia lsV o l 1 4 (O c to b e r 1 9 8 0 ) p p 2 8 6 -2 9 6I s o t he r m a l c r e e p t e s t s ha ve be e n c a r -d e d o u t o n u n r e i n f o r ce d a n d g l as s f i b rer e i n f o r c e d p o l y p r o p y l e n e s a m p l e su n d e r u n i a x i a l t e n s i o n . E x p e r i m e n t sw e r e pe r f o r m e d a t d i f f e r e n t s t r e s sl e ve l s a nd a t va r i ous t e m pe r a t u r e s upt o 60 C . T he i n i t i a l t i m e - i nde pe nde n td e f o r m a t i o n o f t h e p o l y p r o p y l e n ea ppe a r s t o s how c ha r a c t e r i s t i c s t yp i c a lo f a n e l a s ti c s o l id . T he s ubs e qu e n tt i m e - d e p e n d e n t d e f o r m a t i o n i n c r e a s e sw i t h t i m e a nd s t r e ss t yp i f y i ng v i s c oe l as -t i c be ha v i o u r . I n c o r p o r a t i o n o f g l a ssf i b r e s i n t o t h e p o l y p r o p y l e n e r e n d e r st he s t r uc t u r e l e s s de f o r m a b l e ; t he c om -p l i a nc e i s r e duc e d a nd t he v i s c oe l a s t i ce f f e c ts a r e s u pp r e s s e d .O n t h e p r o b a b i l i t y o f f a i l u r e I n t h ec h a i n - o f - b u n d l e s m o d e lB e r g m a n , B o J o u rn a l o f C o m p o s i t eM a t e r i a l s V o l 1 5 ( J a n u a r y 1 9 8 1 )p 9 2A c h a i n - o f b u n d l e s m o d e l i s u s e d t og i ve r e f i ne d bounds on t he a s ym pt o t i c .s t r e ng t h d i s t r i bu t i on o f a un i d i r e c t i ona lf i b r e c om pos i t e , a pp l i c a b l e t o a ge ne r a lf a i l u r e m ode l .

P r o p e r t y c h a n g e s o f a g r a p h i t e /e p o x yc o m p o s i t e e x p o s e d t o n o n i o n i z i n g s p a c ep a r a m e t e r sP h e l ps , H e n r y R . a n d L o n g , E d w a r d R .Journa l o f Com posi te Materia ls Vo l 14(O c to b e r 1 9 8 0 )p p 3 3 4 -3 4 1A s t u d y h as b e e n m a d e o f t h e c h a n g e si n m a s s , t h i c kne s s a nd f l e xu r a l p r ope r -t i es o f i n i ti a ll y w e t a n d d r y s pe c i m e nso f g r a p h i te / e p o x y c o m p o s i t e s p e c i m e n sd u e t o t h e e q u i v a l e n t o f e i g h t w e e k s o fe x p o s u r e t o n o n i o n i z i n g s p a c ee n v i r o n m e n t a l p a r a m e t e r s . T h e s ep a r a m e t e r s w e r e n e a r a n d m i d d l e s o l a ru v i r r a d ie n c e , h i g h v a c u u m a n d t e m p -e r a t u r e . C h a n g e s w e r e o b s e r v e d i n t h em a s s , d i m e n s i o n s a n d s u r f a c e m o r -p h o l o g y o f t h e s p e c i m e n s , t h o u g h t h ef l e xu r a l p r ope r t i e s w e r e no t a f f e c t e d .C o m b i n e d u v a n d e l ev a t ed t e m p e r a -t u r e e n v i r o n m e n t s h a d s y n e r g i s t i ce f f e c ts on t he p r ope r t i e s o f the s pe c i -m e n s .S t r e s s f i e l d e v a l u a t i o n i n p h o t o e l a s t i ca n i s o t r o p i c m a t e r i a l s : e x p e r i m e n t a ln u m e r i c a l t e c h n i q u eV o l o s h i n , A r k a d y J o u r n a l o f C o m p o -si te Materia ls Vo l 14 (Oc tober 1980)p p 3 4 2 - 3 5 0A n e x p e r i m e n t a l n u m e r i c a l t e c h n i q u eha s be e n de ve l ope d f o r s t r e s s f i e l de va l ua t i on i n pho t oe l a s t i c a n i s o t r op i cm a t e r i a l s . T he m e t hod i s ba s e d onus i ng e xpe r i m e n t a l da t a a nd ba s i c e l a s -t i c i t y t h e o r y t o o b t a i n a n o v e r d e t e r -m i n e d s o l u t i o n , a n d i s c o m p a r e df a vou r a b l y w i t h r e s u l t s ob t a i ne d by t w oo t he r te c hn i qu e s ( f i n it e e l e m e n t a ndm od i f i e d s he a r d i f f e r e nc e ) . A pp l i c a t i ono f the a na l y s i s f o r e xpe r i m e n t a l e v a l ua -t i on o f s t r e s s - in t e ns i t y f a c t o r s , a s w e l la s s t r e s s f i e l d de t e r m i na t i on ne a r ac r a c k t i p i s p r opos e d .S t u d i e s o f i m p a c t e d g l a s s f ib r e -r e i n f o r c e d c o m p o s i t e l a m i n a t e sT a ke da , N . , S i e r a kow s k i , R . L . a ndM a l v e r n , L . E . SA M P E Quarterly Vo112N o 2 ( J a n u a ry 1 9 8 1 )p p 9 -1 7A n e x p e r i m e n t a l i n v e s t i g at io n o f t h es e que n t i a l de l a m i n a t i on o f c e n t r a l l yi m pa c t e d c om pos i t e l a m i na t e s i s r e p -o r t e d . T he m a t e r i a l s u s e d w e r e g l a s sf i b r e / e p o x y m a n u f a c t u r e d w i t h p r e p r e gt a p es . P a r a m e t e r s s u c h a s i m p a c t o rnos e s ha pe , i m pa c t o r m a s s a nd k i ne t i ce ne r gy , a nd p l y o r i e n t a t i on w e r e va r i e dt o a s s e s s t he i r e f f e c t s on t he f r a c t u r eb e h a v i o u r o f t h e l a m i n a t es .S t u d i e s o f s t r u ct u r e i n c a r b o n i z e d c o m -p o s i t e s f r o m a p h e n o l i c r e s i n a n d o x i d -i z e d P A N f i b r e s u s i n g c h r o m i c a c i d a s a ne t c h a n tM a r k o v i c , V e s n a , a n d M a r c h , H a r r y

C a rb o n V o l 1 9 p p 2 0 9 -2 1 1Phe no l i c r e s i n / PA N f i b r e c om pos i t e sw e r e p r e p a r e d w i t h h e a t t r e a t m e n t s a ta n u m b e r o f t e m p e r a t u r e s b e t w e e n 4 2 3a nd 1173 K . O p t i c a l a nd s c a nn i ng e l e c -t r o n m i c r o s c o p y o f p o l i s h e d s u r f a ce si nd i c a t e d a f u s i ng o f the t w o m a t e r i a lsi n t o a h o m o g e n e o u s m a t r i x . H o w e v e r ,SEM o f s a m p l e s e t c he d w i t h c h r om i ca c i d s how e d t ha t t he i de n t i t y o f t hem a t e r i a l s w a s p r e s e r ve d . T r a ns ve r s es e c t i ons o f PA N f i b r e s he a t t r e a t e d a tg r e a t e r t he n 973 K e xh i b i t e d a s e l e c -t i ve e t c h i ng s ugg e s t ive o f a s t r a i n / c o r ef i b r e c om pos i t i on .T h e r m o m e c h a n i c a l p r o p e r t i e s o f p a r t i -c le c om pos i t e s i n t h e i r t r a n s i t i o n r e g i o nPa i pe t i s , S . A . Fibre Sc ience and Tech-n o lo g y V o l 1 3 N o 6 (N o v e m b e r 1 9 8 0 )p p 4 4 9 -4 6 3A n i n v e st i g at i o n w a s c a r ri e d o u t o n t h et h e r m o m e c h a n i c a l b e h a v i o u r o fpo l ym e r i c m a t e r i a l s c on t a i n i ng f i l l e rpa r t i c l e s in t he r e g i on o f t he g l a s st r a ns i t ion t e m pe r a t u r e o f t he m a t e r i a ls .I t w a s s how n a na l y t i c a l l y t ha t i n t r oduc -i ng s uc h r e i n f o r c i ng pa r t i c l e s w ou l di n c r e a s e T g t o a n e x t e n t p r o p o r t i o n a lt o t he r e i n f o r c i ng e f f e c t . P r e v i ous l yr e p o r t e d e x p e r i m e n t a l w o r k c o n f i r m st h i s a na l y t i c a l p r opos i t i on , e xc e p t f o rc om pos i t e s i n w h i c h m a t f i x / pa r ti c l ebond i ng i s poo r . T h i s l a t e r w a s c on -f i r m e d b y e x p e r i m e n t s . P a r t i c l eg e o m e t r y a n d t o p o l o g y w e r e f o u n d t oa f f e c t T g c ons i de r a b l y .T h i c k n e s s a n d l a m i n a t i n g e f f e c t s o nf r a c t u re b e h a v i o u r o f g la s s f i b re c o m -p o s i t e sG a r g , A . C . Fibre Sc ience and Techno l-ogy Vo l 14 No 1 (January 1981)p p 2 7 - 3 9T he e f f e c t o f l a m i na t e t h i c kne s s a ndm e t h o d o f la m i n a t i o n o n t h e f r a c tu r eo f r a ndo m g l a s s f i b r e - r e i n f o r c e d r e s i nw a s s t ud i e d u s i ng R - c u r ve s . I t w a sf ound t ha t t h i c kne s s d i d no t s i gn i f i c -a n t l y a f f e c t t he f r a c t u r e c ha r a c t e ri s t ic s ,bu t t ha t de l a ye d l a m i na t i on ( t ha t i s ,p r e p a r e d o v e r a p e r i o d o f 4 d a y s) d o e st o s o m e e x t e n t . U s i n g t h e R - c u r v e s ,a n a l y t i c a l r e l a t i o n s h i p s h a v e b e e nd e v e l o p e d a n d t h e s e w e r e u s e d t o p r e -d i c t t he r e s i dua l s t r e ng t h c ha r a c t e r i s t i c sa nd t he f r a c t u r e t oughne s s .

T o u g h n e s s t e s t i n g o f c o m p o s i t e m a t e r i -a lsM i l l e r , A . G . , H e r t z b e r g , P . E . a n d R a n -t a l a , V . W . S A M P E Q u a r t e r l y V o l 1 2N o 2 ( J a n u a ry 1 9 8 1 )p p 3 6 -4 2T h e d e v e l o p m e n t o f fr a c tu r e t o u g h n e s sa n d i n s t r u m e n t e d i m p a c t t es t in g p r o c e -

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dures for advanced composite materialsis described. These tests are sensitive tochanges in fibre lay-up and to theproperties of the resin matrix used.Data obtained indicate that rate-sensitive matrix materials are not rate-sensitive in the composite. It is shownthat limited correlation between thetest types can be made, although it isstated that such correlations arequalitative rather than quantitative.

Transverse hehaviour of unidirectionalr i b b o n r e i n f o r c e d M e t g l a s / e p o x ylaminatesYeow, Y.T. J o u rn a l o f C o m p o s i t e M a t -e r ia l s S u p p le m e n t V o l 1 4 (1 9 8 0 ) p p1 3 2 -1 4 3A finite element analysis is used tomodel the elastic behaviour of anepoxy based, rectangular shaped,metallic glass reinforced composite.The effects of reinforcement aspectratio, volume fraction, overlap and thedistance between reinforcement on thetransverse moduli and strength are det-ermined. Comparisons of experimentaldata with results obtained from thefinite element analysis and theHalpin-Tsai equations are made. Theinfluence of the various compositeparameters studied on the transversecomposite strength are identified.Two-dimen s ional f in i te e lement analys i sof hi-modulus m aterialTabaddor, F. F ib re S c i e n c e a n d T e c h -n o lo g y V o l 1 4 N o 3 (A p r i l 1 9 8 1 )p p 2 2 9 - 2 4 0T h e properties of polyester cord/rub-ber and boron/epoxy composites havebeen calculated in terms of the con-stituent properties and the 'effective'cord compression modulus. The finiteelement formulation of the problem isdiscussed and an iterative scheme ofsolution is proposed.

METAL MA TRICESCast a luminium al loy composi tes con-mining copper-coated ground mica par-ticlesNath, Deo and Rohatgi, P.K. J o u rn a lo f Materia ls Sc ience V o l 16 (1981 ) pp1 5 9 9 -1 6 0 6By copper coating mica particles it ispossible to increase their wettability byaluminium alloys, and to achieve highlyloaded composites suitable for self-lubricated bearings. Thei r fabrica tionand microstructure are discussed withreference to their mechanical proper-ties.

Electrical anisotropic prope rty of som eunidirectionaily solidified eutectic alloysMoon, I.H., Kim, Y.L. and Ahu, I.S.Jounra l o f Materia ls Sc ience Vo l 16(1 9 8 1 ) p p 1 3 6 7 -1 3 7 3Unidirectionally solidified Cd-Pb,Bi-Cd, and Bi-Zn eutectics showedanisotropic electrical resistivities con-sistent with calculated values based ontheir microstructure.On the microstructure morp hology ofeutectic Co-Cr-C based superaHoysHildebrandt, Uwe W. Ze i tschri f l FurM e ta lk u n d e V o l 7 2 N o 4 p p 2 6 1 -2 6 5T h e influence of varying parameters ofheat treatment and solidification onmicrostructure morphology of thedirectionally solidified in-situ composite'C73' was studied using methods ofquatitative metallography. Ripeningphenomena were observed which werestronger for cyclic heat treatment thanfor isothermal heating. Furthermore,stable carbide configurations existed forthe base alloy, which could besuppressed by alloying further elements.

Preparation and properties of casta luminium-ceramic partic le composi tesSurappa, M.K., Rohatgi, P.K. J o u rn a lo f Materia ls Sc ience V o l 16 (1981)p p 9 8 3 -9 9 3Alumina, illite, and silicon carbide par-t i c l e s w ere i nco rpo ra t ed i n toaluminium alloy melts at up to 3 weight% after a heat treatment to promotewetting. Their processing, microstruc-ture, mechanical properties, wear resis-tance, and particle distribution are fullydiscussed.On the spec imen dependence of uni -directional boron /alum lnium fracturetoughnessReedy, E.D. Jr. J o u rn a l o f C o m p o s i t eMateria ls Supp lement Vo l 14 (1980)p p 1 1 8 -1 3 1Fracture toughness of unidirectionalboron/aluminium was measured andwas found to be specimen dependent,indicating that fracture toughness is nota material property for the size andtype of specimen tested. The failuremode was also found to be specimendependent. The failure of linear elasticfracture mechanics to define a materialproperty for these specimens was attri-buted to extensive matrix yielding inregions remote from the notch tip.Th e U'PAL process: a direct meth od o fp r e p a r i n g c a s t a l u m i n l u m a l l o y -graphite particle compositesKrishnan, B.P., Surappa, M.K. andRohatgi, P.K. Journa l o f Materia ls Sc i-

e n c e V o l 1 6 (1 9 8 1 ) p p 1 2 0 9 -1 2 1 6Aluminium-graphite composites can beused as bearingmaterials, but untreatedgraphite is not wetted by aluminium. Aheat trea tment prior to dispersion allowsup to 3% by weight of graphite to beuniformly distributed. Small additions ofMg and Si aid the process, andmechanical properties of the resultingcomposites are given.

NATURAL COMPOSITESIFIBRESAxial compress ion of a he lica l ly wou ndlaminated paper tubeBeatty, M.F. and Cheng, W.C. J o u rn a lo f C o m p o s i t e M a te r ia ls S u p p le m e n t V o l1 4 (1 9 8 0 ) p p 4 2 -5 6An experimental investigation of thecompressive deformation behaviour ofhelically wound, laminated paper tubesis described. It is found that the tota langle of twist reaches a critical value atroughly the same time that the axialcompressive force achieves a maximumvalue at which the cylinder walls buckleby folding inward along the helicalfibre lines of the tube. Empirical equa-tions relating the critical angle of twistand the subsequent uniform, post buck-ling twisting rate to the tube length arepresented.Copp er coat ing on co i l f ibresParithran, C., Gopakumar, K., Prasad,S.V. and Rohatgi, P.K. J o u r na l o f M a t -eria ls Sc ience Vo l 16 (1981) pp 1548-1 5 5 6Continuous 1.5 to 5/~m copper coat-ings decrease the electrical resistivityand flame propagation o f coconut palmfibre, while also increasing by 25% thetensile and flexural strengths of polyes-ter matrix composites fabricated fromthe fibre. The deposition of copperfrom Fehlings-formaldehyde solution isdescribed.Electr ica l res i s t iv i ty and die lectr icstrength of plant f ibresKulkarni, A.G., Satyanarayana, K.G.and Rohatgi, P.K. Journa l o f Materia lsS c i e n c e V o l 1 6 (1 9 8 1 ) p p 1 7 1 9 -1 7 2 6Resistivity and dielectric strength o f avariety of natural fibres are shown tobe strongly dependent on moisturecontent, and also total cellulose con-tent. Thei r suitability for insulatingapplications are discussed with refer-ence to their chemical and physicalstructure and properties.

An investigat ion of som e matr ix prote incomponents crit ical to the extensibleproperties of insect cuticle

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