PSI - Issue 37

S. Valvez et al. / Procedia Structural Integrity 37 (2022) 738–745

741

4

S. Valvez et al. / Structural Integrity Procedia 00 (2019) 000 – 000 = 2 3 ℎ 2

(1)

where P is the load, L the span length, b the width and h the thickness of the specimen. The hardness was evaluated at room temperature by micro-indentation using an HMV-G SHIMADZU tester, applying a load of 98.07 mN (HV 0.01) for 15 seconds. The volume variation of the specimen was evaluated with at least four measurements along its length and 10 measurements along its width and thickness. Finally, the radius of curvature (R) of the specimens, resulting from the effect of temperature, was evaluated using a Mitutoyo PJ-P1010A profile projector. According to Figure 1, the variables d and c were obtained using this equipment, while the radius (R) was calculated using equation (2):

d

c

R

Fig. 1. Scheme used to determine the radius of curvature (R). = 2 + 4 2 8

(2) The inverse radius of curvature (1/R) was used to compare the effect of the annealing treatment on the final

geometry of the samples. 3. Results and Discussion

Figure 2 shows the general appearance of the specimens after being submitted to the annealing treatment. It is possible to observe that there were some geometric alterations of the specimens, which will be analyzed in detail.

a) c) Fig. 2. General appearance of the annealed samples for the different materials: a) PETG; b) CFPETG; c) KFPETG. b)

As shown in the previous figure, after the annealing heat treatment, the specimens changed their configurations and geometric dimensions. To assess the dimensional changes, Table 3 presents the mean values in terms of volumetry (change of dimensions along the x, y and z axes) and respective standard deviation for all materials and test conditions. Regarding the radius of curvature (R) observed for each material and specific condition, Table 4 presents this information in terms of inverse radius of curvature (1/R) to compare the effect of the annealing treatment on the final geometry of the samples. Both conditions prove to be decisive for design considerations because, in addition to guaranteeing the load carrying capacity, any component must guarantee that its dimension and geometry are kept within very tight tolerances.