PSI - Issue 61

Zili Huang et al. / Procedia Structural Integrity 61 (2024) 252–259 Huang et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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(Figs. 3b, 3d and 3f) correspond to times indicated in the plots of load, and displacements against time (Figs. 3a, 3c, 3e).

Fig. 3. (a, c, e) Evolution of load, vertical displacement and lateral displacement with time; (b, d, f) Load-displacement curves for three tests (90° loading angle).

In Fig. 3b, the load-displacement curve indicates the loading behaviour of point 1 and point 2 are almost linear within the pre-peak stage before reaching the peak load at point 3 under diametrical compression. Meanwhile, the results of Fig. 3a shows the lateral displacement increases linearly under control. The vertical displacement exhibits nonlinear increase before reaching the peak load. After reaching the peak load at point 3, the load starts to drop gradually while the vertical displacement still grows slightly and gradually tend to be stable after 3 hours. Moreover, Figs. 3f and 3e both show that the vertical displacements tend to be stable after reaching the peak load value with lateral control. Therefore, the AUSBIT setting can keep adjusting the vertical loading rate to maintain the predefined constant rate of lateral displacement which can capture post-peak evolution of cracking of 90 loading angle specimen. Overall, the results show that the lateral deformations increase linearly and monotonically at both pre-peak and post-peak stages, as specified in the MTS control feedback. This indicates a steady failure process, given the decrease of both load and vertical displacement in post-peak stage does not lead to decrease of lateral displacement in all three