1011

B*tIt~~~~;t~ (A!ilil)59 ~ 560 '.2j- (1993-4)

ffifH)( No. 92-1322

~ :fr Z -ffi*I, w* ~*21$ ;$: ~7..1l1*2, Siegfried SCHMAUDER*3

Finite Element Analysis on Fracture of WC-Co Hard Alloys

Yukinobu MORIYA, Shigeru AOKI,Kikuo KISHIMOTO and Siegfried SCHMADDER

An elastic-plastic finite element analysis of the crack-tip field in a WC-Co alloy was performedto achieve a detailed understanding of ductile fracture in a Co-phase. A model in which a Co-phasewas embedded at the crack tip in an elastic solid was employed, and Gurson's constitutive equationsfor porous plastic material were used for the Co-phase in order to take into account the nucleationand growth of the microvoids. The effects of the shape of the Co-phase and the stress state (planestress or plane strain) on the distributions of hoop stress, hydrostatic stress and microvoid volumefraction were discussed using the computational results. The process of ductile fracture underconstraints of deformation was also discussed.

Key Words: Ductile Fracture, WC-Co Alloy, Finite Element Analysis, Gurson's ConstitutiveEquations, Microvoid, Hydrostatic Stress

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1016

10

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100010010

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-1.0

0.1 I I I I 111111 I I I 111111 I I Irr 1111 I I I t, 1111

0.1 I 10 100 1000

Ro/ do

(b) iE:1J%O) Co

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O:a=90'X: a;::; 45·

K/K1C= 0. 4Ro/do=\. 0, e=o'

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tJi~%j{;j*O)~~:a:i1?g; 'J~ftt.t\-\~ \-\-5 *,amtJiflJ0

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jlf,f'iH:j:Ht~ C 0 O).fl.!j~iIH:-:J\-\"(, fR!uJ'~.j'LO)~jo~JiJt:R:a:~J.f.f:An"'(fi~ß!~*IYHJTHJ~'?t.:.

~O)*,am, CoO)%~ttJiM7.kEE~'51HC;1J,fRXJJ'~.j'LO)

~m.~~a.~8000)(•• 0).~~~~)~re~~~4~~~~:a:~0~~l." z:n00)z:~:a:"t.~An "'(5~\-\~%j{;j*Tf:~ ft G.fl.!j~l1iU:-:J\-\"'(~~l.,t.:.

*~X~(1) jj(OJ!ll . {tlJ2.:g, UIlIDm, 53-494A(l987),1870.

(2) *j)!jl . {tlJ2.:g, UIlIDm, 56-532A(l990) ,2417.

(3) {ti:~. ::$:EE, 3FlilR.~1!l', 39-3(1990),237.

(4) Sigl,L.S. and Exner,H.E., Metall. Trans.

A, 18A(1987), 1299.

(5) Fisehmeister,H.F., Sehmauder,S. and Sigl,

L.S., Mater.Sei.Eng, AI05/106(1988), 305.

(6) Gurson,A.L., J.Eng.Mat.Teeh., 99(1977),2.(7) ~* . fflJ 3.:g, UIlIDm, 52-481A(l986), 2249.

(8) Needleman,A. and Riee,J.R., Meehanies of

Sheet Metal Forming, PI~num, (1978), 237.

-134 -

Transactions of the Japan Society of

Mechanical Engineers

59~ 560% A *ii

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