PSI - Issue 68

Zili Huang et al. / Procedia Structural Integrity 68 (2025) 266–271 Z. Huang et al. / Structural Integrity Procedia 00 (2025) 000–000

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specimens are cured for 28 days in the fog room at UoA under consistent storage environment. All specimens are removed from fog room after curing period and dried in ventilated place outsides.

(a) (b) Fig. 1. (a) Disc specimen cut from printed block; (b) Three different sizes of disc specimens.

2.3. Test setup using AUSBIT & Fracture energy concept The disc specimens, after 28 days of curing period, are used in indirect tensile tests to examine the interlayer bond between layers. MTS loading frame is set up with circular flat loading platens with a load capacity of 300 kN and cooperates with two vertical Linear Variable Differential Transformers (LVDTs) for vertical displacement measurement and one lateral LVDT for lateral displacement measurement and rate control as show in Fig. 2. AUSBIT (Verma et al, 2021) focuses on the lateral deformation of the disc specimen during the top loading platen compresses the specimen. Snap-back behaviour is captured thanks to feedback from the lateral LVDT, so that the predefined lateral rate is kept constant for stabilizing the cracking process. A combination of vertical (for early stage of loading) displacement rate as 0.2mm/min with 1 kN as load set point and lateral (for the remainder of the test) displacement controlled loading is employed. The specified lateral deformation rate is about 1.2 µm/ min with serval trials for an optimal setting currently.

Lateral LVDT

Fig. 2. MTS loading frame set up with vertical and lateral displacements measurement (rear view).