Crack Paths 2009

R E S U L T S

Full Model versus B L M

The B L Mformulation is a promising approach that can be applied to various cracked

geometries, including surface cracks, to minimize the computational effort, see e.g. [7].

acting normal to the

σ22 and ε22,

Figure 4 compares the stress and strain components,

crack propagation direction in the ligament, for the initial stationary crack subjected to

monotonic loading with Kmax = 20 and 24 M P a √ mfor the M(T) and C(T) specimens,

respectively. Except for slightly different strain distributions near the crack tip in the

M(T) specimen, the agreement between the solutions for the full models and B L Mis

fairly good.

0.012340.000

0.003

0.006

0.009

,

M(T) BLM C )

M(T)

M(T) BLM

C(T) BLM

S t r a in ,

s

t r e

18024600.00 0.02 0.04 0.06 0.08 0.10 Distance from crack tip [mm] S

Distance from crack tip [mm]

Figure 4. Stress and strain distributions ahead of a stationary crack tip in M(T) and

C(T) specimens, monotonic loading.

0.01024680 .000

0.003

0.006 M(T) 1st cycle

0.009

M(T) 1st cycle 10th cycle 36-BLM 1s0tthcycclyecle 36

M(T) 10th cycle

M(T) 30th cycle )6

M(T)-BLM 1st cycle

M(T)-BLM 10th cycle 3 cycle

, 2 2

, 2 2

S t r a in

M(T)-BLM 60th cycle

s s

t r e

16802400.00 0.02 0.04 0.06 0.08 0.10 Distance from crack tip [mm] S

Distance from crack tip [mm]

Figure 5. Stress and strain distributions ahead of a growing crack tip in M(T)

specimen, cyclic loading.

However, the above conclusion does not hold for a crack propagating under cyclic

loading. For the M(T) specimen, Fig. 5 demonstrates increasing deviation between the

full specimen and B L Msolutions with increasing number of cycles. Possible

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