## 3 Results
### Fracture Analysis  
Figure 4 shows sketches of the evolution of the fracture in the N samples during the tensile test. The fracture mechanism is divided into five stages, starting from the zero point of the  
Figure 3: Mechanical properties comparison of the different samples obtained from the stress–strain diagrams, (**a**) UTS, (**b**) Young’s modulus, (**c**) strain, and (**d**) toughness. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multirow{2}{*}{**UTS (MPa)**} & \multicolumn{2}{c}{**Strain**} & \multirow{2}{*}{**E (GPa)**} & \multirow{2}{*}{**T (M/m3)**} \\  & & **(mm/mm)** & & \\ \hline N & 3.20 (1.70\%) & 0.0009 (2.27\%) & 0.04 (0.87\%) & 0.17 (4.72\%) \\
0.5 &  
graph. Stage 1 corresponds to the starting point, where zero stress equals zero deformation; separation phenomena between the stitching and the matrix occur as the tensile stress increases. At stage 2, due to the stresses generated in the center of the sample, pre-cracking on the matrix begins to appear, and there is little matrix detachment, making internal pull-out fibers occur. The pre-cracking has trajectories like the direction of the fibers within the composite. In stage 3, small fractures in the matrix within the direction of the fibers appear, and transversal cracks are formed, which contribute to the detachment of a greater amount of matrix from the composite, resulting in internal fiber pull-out. During stage 4, the fibers externally pull out due to bigger fractures and cracks, and matrix detachment begins. This is a chain reaction that ends at stage 5 by separating the sample into two parts, and the crack line coincides with the direction of the reinforcing fibers. Figure 5 shows the SEM images of the fracture analysis of the N sample, where stages 3, 4, and 5 were identified as shown in Figure 4. Figure 5a shows a fractured NA specimen, where we can observe the beginning of the fibers pulling out from the matrix on the surface of the fracture, in addition to the areas that correspond to where each of the stages of the fracture are located. This is because the fracture of a composite material is progressive, starting from the center of the specimen and moving to its end. Figure 5b,c correspond to stage 3 of the fracture, where cracks are observed in the direction of the stitching and vertical cracks that favor the detachment of the matrix. Figure 5d,e correspond to zone 4 of the fracture, where the detachment of the matrix and pull-out of the fibers are observed, indicating the material's weakening. Figure 5f,g correspond to the fracture, where the fibers are observed to be separated from the matrix, resulting in delamination [30]. Figure 4: Evolution of the N sample fracture mechanism. The fracture mechanisms in the stitched samples were almost identical, with no significant difference between each other to report. By avoiding redundancy, the 0.5C sample was chosen as a representative specimen on the stitched samples to make the consecutive analysis. Figure 6 represents sketches of the evolution of the fracture in the stitched samples. The fracture analysis is also divided into five stages. Stage 1 commences  
Figure 5: (**a**) Tensile fractured NA specimen, (**b,c**) stage 3 of fracture, the pre cracking on matrix, (**d,e**) stage 4, formation of transverse cracks, (**t,g**) stage 5, fracture, pull-out of fibers, and detachment of matrix. the tensile test, where zero stress equals zero strain, and separation between the stitching, the fibers, and the matrix occurs as tensile stress increases. In stage 2, the matrix begins to crack as the tensile stress increases. As shown in Figure 3b, the strain can decrease by as much as 50% because the stitching helps to keep the fiberglass in place. The stitching points behave as stress concentrators and thus prevent cracks from propagating along the fiberglass of the reinforcements, thus delaying fiberglass pull-out.