Table 2.

As you can see, the results for these cases were close, with the exception of the values L=a ¼ 0, 8. Some differences in them are due to different localizations of applied tractions.

The results of the calculations of SIF are given in Table 3 for the case R ! 0, γ ¼ 0, that is, the case is considered when forces are applied at the center of the holes and more smoothly applied efforts (at γ ¼ π=8).

The results for a circular sample with γ ¼ π=8 are shown (Figure 12) in the same table.

The following conclusions are made based on Tables 2 and 3: SIF does not differ significantly in the case of distributed loads with different degrees of localization, SIF increases somewhat with the growth of the domain of action of tractions, and SIFs are bigger at small crack lengths at point action of tractions (at R ! 0) and at all lengths with α>0, 6. SIFs in a circular sample are bigger than in a square one under the same load conditions.

Similar results for a square sample made from a LU material are given in Table 4. Here, the relative SIFs Ka in which the crack length is explicitly taken into


#### Table 3.

Relative SIFs for a square and circular sample, isotropy.

Figure 12. Circular sample with holes and a crack.

Determination of Stresses in Composite Plates with Holes and Cracks Based on Singular Integral… DOI: http://dx.doi.org/10.5772/intechopen.87718


#### Table 4.

Relative SIFs Ka for square sample, LU material.


#### Table 5.

Relative SIFs for a circular sample, LU material.

account and the case where the crack is parallel to the direction of bigger stiffness (data on the left) and is perpendicular to it (data on the right) are given.

Similar results for a circular sample for the same material are given in Table 5.
