Crack Propagation in a Corner Bracket
This post provides another example on the modelling of crack growth in ANSYS APDL based on the algorithm described in my previous post (APDL macro is provided).
Demonstration
Geometry
The interest of this analysis is in the effect of the middle hole size on the crack path that is assumed to initiate from point A under $\theta=45^{\circ}$ with respect to the global coordinate system.
The geometry of this sample and the initial mesh is shown in the following figures.
The geometry can be generated using the following macro:
FINISH
/clear
/prep7
T1 = 10
T2 = 10
D1 = 5
D2 = 5
D3 = 5
L1 = 20
L2 = 5
R = 5
k
k,,L1
k,,L1,T1
k,,,T1
l,1,2
l,2,3
l,3,4
l,4,1
k,,L1
k,,L1+R
k,,L1+R,-R
k,,L1+R+T2,-R
k,,L1+R+T2
k,,L1+R+T2,T1
k,,L1+R,T1
k,,L1,T1
l,2,6
l,6,11
l,11,12
l,12,2
l,6,7
l,7,8
l,8,9
l,9,6
l,6,9
l,9,10
l,10,11
l,11,6
k,,-R
k,,-R,T1
l,1,13
l,13,14
l,14,4
k,,L1+R,-R-L2
k,,L1+R+T2,-R-L2
k,,L1+R,-R-L2-R
k,,L1+R+T2,-R-L2-R
l,7,15
l,15,16
l,16,8
l,15,17
l,17,18
l,18,16
LFILLT,5,9,R, ,
LFILLT,13,14,R, ,
LFILLT,17,16,R, ,
LFILLT,15,16,R, ,
LFILLT,21,22,R, ,
LFILLT,22,23,R, ,
k,,,T1/2
circle,18,D1/2
k,,L1+R+T2/2,-R-L2
circle,26,D2/2
ldele,6
ldele,12
k,,L1,T1/2
circle,31,D3/2
LPTN,ALL
al,32,17,9,36,22,23
al,1,33,30,12,35,3,36,21,25,32
LSEL,S, , ,24
LSEL,A, , ,10
LSEL,A, , ,11
LSEL,A, , ,13
LSEL,A, , ,5
LSEL,A, , ,14
LSEL,A, , ,34
LSEL,A, , ,35
LSEL,A, , ,6
LSEL,A, , ,31
LSEL,A, , ,33
al,all
allsel,all
al,18,37,27,26,38,20,10
al,37,15,16,38,29,28
APTN,ALL
! finite element
ET,1,82
KEYOPT,1,3,2 !plane strain conditions
! isotropic elasticity
MP,EX,1,210000
MP,PRXY,1,0.3
LCCAT,17,9
LCCAT,22,23
LCCAT,15,16
LCCAT,28,29
LSEL,S,,,36
LSEL,A,,,21
LSEL,A,,,25
LSEL,A,,,32
LCCAT,ALL
allsel,all
LSEL,S,,,35
LSEL,A,,,12
LSEL,A,,,30
LSEL,A,,,33
LCCAT,ALL
allsel, all
LSEL,S,,,37
LSEL,A,,,27
LSEL,A,,,26
LSEL,A,,,38
LCCAT,ALL
allsel, all
ESIZE,0.8,0,
MSHAPE,0,2D
MSHKEY,1
AMESH,1
AMESH,5
MSHKEY,0
AMESH,2
AMESH,4
FK,23,FY,100 !100 N force
DK,28,,,,0,UY
DL,13, ,UX,
DL,11, ,UX,
DL,20, ,UX,
LDIV, 24, 0.5
ldele,39
ldele,40
ldele,41
LSEL,R,LCCA
LDELE,ALL
allsel,all
kdele,14
kdele,18
kdele,31
kdele,5
kdele,6
kdele,17
kdele,26
kdele,10
LDIV, 44, 0.01
LDIV, 24, 0.99
Results
Interestingly, the crack propagates toward the hole, and for the case when $d=7.4$mm the crack gets arrested within the hole. Designing structural features such as holes may improve the lifetime of the system by arresting the existing crack.