**Conflict of interest**

*Composite and Nanocomposite Materials - From Knowledge to Industrial Applications*

zone of discontinuities, the stress-strain relationship for planar composite structures

*Finite element and DIC engineering strain fields for [0]4 notched laminated plate with a 5/(4.5, 4.5)/(7, 7)* 

The SCF results tabulated in **Table 2** are actually the average of three values obtained for each specimen. One can see that the experimental results are in good agreement with finite element outputs and the difference between them is insignificant. In addition, one can clearly see that the stress concentration near circular cutouts can be reduced using two auxiliary holes (see **Figure 5**). So, it can be concluded that the stress concentration reduction explains the tensile strength load

Notches with different forms and sizes are unavoidable in composite laminates to satisfy the needs of some design requirements. The stress developed around these notches reduces the load-bearing capacity of these composite structures. The accuracy of the analysis of these kinds of structures is based on the choice of an appropriate strategy. In the present investigation, DIC technique was used to the assessment of stress distribution taking place in laminates with different notch sizes loaded in tension. In addition, FEM is also used to validate the distribution of stresses obtained experimentally and investigate the tensile strength degradation in these laminated plates. It has been shown that the ultimate strength degradation and final damage mechanism that appear after the final failure are depending on the open hole size and strain distribution. One can see that the SCF and the damage zones increase and the perforated plate strength decreases with the increase in the hole size. Moreover, to improve the ultimate strength values, the DHS technique was used. DHS is introduced to these structures as a strategy to increase the ultimate strength as well as the weight of the structures. Based on the experimental results, the ultimate strength can be improved by introducing two

was used. DIC technique measurements were carried out in all the samples.

improvement in specimens with DHS.

circular auxiliary holes along the principal stress directions.

**5. Conclusion**

**Figure 5.**

*DHS configuration.*

**178**

The authors declare no conflict of interest.
