Issue 3

M. Zakeri et

al., Frattura

ed Integrità S

trutturale, 3

(2008) 2 - 10

F

igure 6. Load

ing frame em

ployed to app

ly compressi

ve load on th

e disks and de

finition of the

characteristi

c dimensions .

Figure

7. Isochroma

tic fringes aro

und the crack

tips of the d

isks: a) N-1, b

) N-2.

thod kno sent

show tips f

s the resulta or the two d

nt isochrom isks.

atic fringes a

round the c

rack

and the m wn paramet ed in Tab. 1 hould be me ct to K II in b crack tips w

ethod of le ers K II , and . ntioned tha oth cases. H as subjected n Experim 4.34 4.82 -0.38 -0.26 mental result ith FEM res ndings pres Brazilian d re mode II ey are com

ast squares. T were c t K I was ve ence it could to mode II c K II [MPa ent FEM 4.7 5.13 T -Stress [M 9 0.40 2 0.27 s obtained f ults [4]. ented in Ta isks contain condition. In pared with 1

Finally, th alculated as ry small wi be assume onditions.

e un- pre th re d that

It s spe the

4 E As s aroun obser with tence term calcu this a using and t lect s ders. gram deter tant n fittin

XPERIME hown in Fi d the crack ved discont the theoret of the T-st can be quan lating the c im, the obta a compute he Image Pr ome data p These data prepared fo ministic tech on-linear eq g process in

NTAL RE g. 7, the ob tips are asy inuous loop ical predicti ress in mod tified by usi rack tip par ined isochro r code prepa ocessing To oints from f were utilize r a full field nique [11]. uations are volves both

SULTS tained pho mmetric in s are in go ons, and co e II conditi ng the comm ameters, K I matic fringe red in MAT olbox was e ringe loops d in another analysis ba In this tech numerically the Newto

toelastic frin both cases. od consiste nfirm the e ons. This st on methods , K II , and T s were analy LAB softw mployed to of different MATLAB sed on the o nique, the re solved, and n-Raphson

ges The ncy xis ress for .For zed are, col- or

m m ]

Specime N-1 N-2

Error

7.9% 6.0%

Pa]

N-1 N-2 le 1. Experi s, compared w erimental fi investigated -stress in pu e results, th

2.7% 2.9% rom the Bra

Tab disk

zilian

pro ver

Exp the of T thes

b. 1 indicate negative v order to va numerical r

that alues lidate esults

sul- the me

6