PSI - Issue 37

Yifan Li et al. / Procedia Structural Integrity 37 (2022) 41–48 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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working day. The crack mouth opening displacement (CMOD) was measured by Instron 2670-132 extensometer with 10 mm gauge length. The setup of octet-truss lattices fatigue crack propagation tests is shown in Fig. 3.

Fig. 3. The setup of lattice fatigue test.

3. Results and discussion The typical displacement varying with cycle numbers curves of octet-truss lattices in different orientations are shown in Fig. 4. The displacement-cycle diagram of octet-truss lattice in tension fatigue test is similar to corresponding curves of lattice under compression-compression fatigue load, showing three-stage fatigue behaviour. In the first stage, the displacement changes rapidly within a few cycles, and then the displacement shows a relatively constant and minimal change in the second stage. At the final stage, the displacement increases very rapidly and the specimen fails within a limited number of cycles.

1.2

Orien-X (220N) Orien-Y (230N) Orien-Z (240N)

1.0

step 3

0.8

0.6

step 2

step1

0.4

Displacement (mm)

0.2

0.0

0

2000 4000 6000 8000 10000 12000

Number of cycles

Fig. 4. Displacement varying with cycle numbers.