PSI - Issue 16

Jaroslaw Galkiewicz / Procedia Structural Integrity 16 (2019) 35–42 Jaroslaw Galkiewicz / Structural Integrity Procedia 00 (2019) 000 – 000

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a

b

c

d

e

f

g

h

i

Fig. 5. Influence of the constraints level on the behavior of the elementary cell with an inclusion having a: (a – c) circular, (d – f) elongated and (g – i) flattened shape

In the case of elongated inclusions, a uniform breaking of the elementary cell is more easily achieved for a low constraints level. In this case, th e ratio of σ maxA /σ maxC determining an approximate position of the AC line is lowest for T/σ 0 = – 1 (Fig. 5f). This finding means that breaking along the plane of symmetry without partial debonding of the inclusion will occur at a lower level of σ max zone A (a “weaker” bond) on the inclusion surface. Simultaneously, in the case of an elongated cell, the probability of elementary cell damage as a result of complete inclusion debonding and a subsequent cracking of the matrix is clearly less likely. This effect is only slightly visible in the case of a flattened cell (Fig. 5g – i). Fig. 5 also clearly shows the influence of the inclusion shape on the mechanisms of cell damage. In the case of flattened cell, it is most difficult to obtain a crack along a single plane. In the case of the elongated inclusion, a uniform crack is more likely to occur. The location of the BC line also indicates a much lower probability of obtaining a complete debonding of the inclusion. The presented results indicate that the inclusion behavior is affected considerably more by its dimension in the plane of crack growth than by the constraints level.

7. Conclusions

An analysis was performed to determine the influence of the inclusion shape and the constraints level on the behavior of the cell located near the crack tip. The results of the analyses indicated that both the inclusion shape and the constraints level significantly affect the way in which the cell containing the inclusion undergoes damage. This effect, in turn, affects the amount of energy absorbed during the fracture process at the cell level (in a microscale).