Issue 15

I. S. Raju et

alii, Frattura ed

Integrità Struttu

rale, 15 (2011)

35-49; DOI: 10

.3221/IGF-ESIS.1

5.05

Int Int

erface Defects erface defect ting and the o G T /G Ic . V ues greater astrophically, ponent G v try Peak Heati ig. 15(a), an malized G T each locatio ues are plotte n the right ti urs at the sh malized G T ce. e individual m ues. This res

– Effect of D s were studie on-orbit col alues of G T than unity r or they co alues need to ng . For entry d friction alo values for tw n, the interf d as a functi p values for oulder of the for  = 0.4 i ode G valu ult suggests t

efect Location d by assumi d condition w /G Ic less tha equire furthe uld mean th be calculated peak heatin ng the craze o values of t ace defect is on of the de all defect loc joggle, Loc ndicating tha

ng a constan ere conside n unity indic r study. Su e mode of and assesse g, the craze c crack edges i he coefficien centered be fect location ations consi ation 0. How t the craze c examined. t opening for

t-length defe red. The res ate that the ch values co fracture is n d. rack surfaces nfluences the t of friction neath the cr . For  = 0 dered. For b ever, the no rack edge in For both  entry peak h

ct at differen ults for the n defect is sta uld mean t ot Mode-I come into c defect defo  for variou aze crack. B (Fig. 15(b)), oth  = 0 a rmalized G T teraction is a = 0 and  = eating is dom

t craze crac ormalized G ble and unlik he defect is dominated. ontact and sl rmations. Fi s locations o oth the left the left tip v nd  = 0.4, for  = 0 is n important 0.4, the G I inated by M

k locations. T values are ely to grow unstable and Hence, the ide past each g. 15(b) and f the defect and right tip alues are con the maximum considerably variable to th values are lar ode I.

Both entry p presented as catastrophic likely to g total indivi other, as sho 15(c) present along the jog normalized siderably sm normalized higher than e defect driv

eak the ally. row dual wn the gle. G T aller G T

hea rati Val cat com En in F nor For val tha

occ nor for Th val

the ing

G II

es were also hat the defec

ger than the

(a) Interface

defect at craze at varyin

crack Locatio g craze crack l

n +1 and defo ocations (defo

rmed configu rmation scaled

rations for int by 20x).

erface defects

ed G T for  = : Normalized rbit cold con dges do not nction of th tions -1 and . Both the le the acreage) of the defec

for  =0.4.

G T

0.

(c defect locatio rfaces displac ence the defe . The maxim ved into the ly the same n is difference f is down the

) Normalized n – Entry pea e away from ct deformat um normal joggle regio ormalized G in behavior joggle curve

(b) Normaliz Figure 15 or the on-o raze crack e alues as a fu t tip at Loca ch a plateau ip (towards cation 0, half

G T

as a functi

on of interface

k heating.

On 16( nor are dec wh geo

-Orbit Cold . F a), and the c malized G T v a (for the lef rease and rea ere the left t metry; at Lo

dition, the cr interact and e interface d 0). As the ft and right t has the high t is in the acr

aze crack su do not influ efect location defect is mo ips have near er value. Th eage, and hal

each other, ions. Fig. 16 ized G T occu n, the norm T values exce at Location .

as shown in (b) presents rs in the acre alized G T va pt at Locatio 0 is due to

Fig. the age lues n 0, the

45