Crack propagation mixed mode
 

Hy!
I have a problem, I am modeling two cracks that are propagating under uniform stress. In experiment they avoid each other at first and than colapse and in my simulation they meet at the middle without avoidance which is wrong. Can any one tell me what I am doing wrong ?

Picture of experiment: http://origin-ars.els-cdn.com/conten...000483-gr6.gif

Picture of my experiment is attached.

I am using KII= 0 criterion for determination of cracks path.

Ansys code for calculating KI and KII for both cracks:

/POST1


PATH,KL,5,,48 ! Definiranje linije pukotine pomocu koje se racuna KI,KII
PPATH,1,1
PPATH,2,5
PPATH,3,6
PPATH,4,427
PPATH,5,428

KCALC,1,,3,, ! Izracun faktora intenziteta naprezanja KI,KII
*GET,KI_L,KCALC,,K,1
*GET,KII_L,KCALC,,K,2
*STATUS,KI_L
*STATUS,KII_L


PATH,KD,5,,48
PPATH,1,734
PPATH,2,737
PPATH,3,738
PPATH,4,1164
PPATH,5,1163

KCALC,1,,3,,
*GET,KI_D,KCALC,,K,1
*GET,KII_D,KCALC,,K,2
*STATUS,KI_D
*STATUS,KII_D

FINISH