## 2 Experimental Setup
These values are consistent with those reported for similar SLA-printed resins, where elastic moduli typically range between 300 MPa and 400 MPa and yield strengths vary between 18 MPa and 25 MPa, as observed in other studies, such as those by [PERSON] et al. (2010). The variations in these mechanical properties concerning printing angle were not taken into account, as they were less than 10 percent, in agreement with prior findings ([PERSON] et al., 2019). This work presents the calculation of the fracture stiffness (critical value of the Stress Intensity Factor, \(K_{Ic}\)) and the Critical Energy Release Rate \(G_{Ic}\). At the onset of fracture, both in the mode I deformation and the opening mode, the calculation was carried out according to the ASTM D5045-99 standard ([PERSON] et al., 2019), using the compact specimen geometry illustrated in Figure 1 and with the dimensions specified below, specifically W = 40 mm, a = 19 mm, d = 2 mm, and B = 10 mm. The compact samples of the study according to three different printings were analyzed by defining the angle formed from the printing base with the initial notch plane. It has also been verified that the direction of printing did not influence the mechanical properties obtained. To gain insight into the effects of the angle on the material under study, three representative angles were selected: 0\({}^{\circ}\), 45\({}^{\circ}\), and 90\({}^{\circ}\) (see Figure 2). The 0\({}^{\circ}\) and 90\({}^{\circ}\) orientations represent extreme cases, where more significant differences in mechanical behavior are expected, if present. The 45\({}^{\circ}\) orientation serves as an intermediate case, which allows for an assessment of mechanical properties in a less extreme scenario. This combination of angles provides a comprehensive understanding of how different printing orientations affect the material's behavior. The test results are presented below in a proper summary. Once printed, the samples were machined to create a sharp initial notch. To machine the notch tip, a blade with a 0.5 mm radius was utilized, following the guidelines outlined in Section 3.1. Figure 1: Compact specimen according to the ASTM D5045-99 standard [31]. Geometry parameters (**up**) and perspective view (**down**) with the dimensions used in the experiments. All sizes are shown in millimeters (mm). Source: own elaboration plotted with Inkscape (v. 1.3.2). Figure 2: Three printing orientations for compact specimens. The printing orientation is drawn with a continuous line and dashed tangential. Source: own elaboration plotted with Inkscape (v. 1.3.2). in the aforementioned standard. Figure 3 illustrates the blade employed to create the notch tip. In addition, compact tensile tests were performed on an Instron 8800 Universal Tester (Instron, Norwood, MA, USA) under crosshead displacement control at a rate of 5 mm/min. These tests were conducted at a temperature of 23 degrees Celsius. The three specimens were tested for each orientation. To ensure accuracy and minimize potential sources of error, the universal testing machine provided precise load and displacement measurements, and the samples were carefully aligned to avoid misalignment. Each test was repeated three times for each orientation to ensure consistency and reduce variability. Additionally, the compliance check method, as per ASTM D5045-99, was used to validate the accuracy of the results. In the next section, the results of the tests are presented in a test summary. The stresses in the selected specimens were also calculated, and they are summarized in the section below.