PSI - Issue 66

Davide D’Andrea et al. / Procedia Structural Integrity 66 (2024) 449–458 D’Andrea et al./ Structural Integrity Procedia 00 (2025) 000–000

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DIC camera

IR Camera

PA12 Specimen

(a)

(b)

Fig. 3. a) MJF PA12 specimen; b) Rapid Fatigue Machine with testing setup.

A series of static tensile tests was performed on 3 specimens under displacement control adopting a crosshead speed of 2.4 mm/min and monitoring the evolution of the superficial temperature with the IR camera with a sample rate of 20 fps. The maximum value of temperature of a rectangular region of interest (ROI) was recorded. One stepwise fatigue test was performed to validate the prediction of the STM, applying the well-established RTM. The stress level was incremented in a stepwise way of 2 MPa every 3000 cycles. The stress ratio was equal to R= 0.1 with a test frequency of 1 Hz to prevent excessive self-heating of the specimen. The superficial temperature was acquired every 10 second to apply the RTM. 4. Results and discussion 4.1. Static tensile test Static tensile tests have been performed on 3 specimens to compare their mechanical properties with the one reported in the HP Datasheet. The stress has been estimated as the ration between the applied force and the cross section of the specimen, while the strain field has been obtained by DIC system. In Fig. 4 are reported the stress-strain curve of the tested specimens (continuous line) and the one from HP Datasheet for ASTM specimens Type I and Type V (dot curves).

Fig. 4. Stress-strain curve of MJF PA12, comparison with nominal values.