PSI - Issue 66

Mansi Gupta et al. / Procedia Structural Integrity 66 (2024) 122–134

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Mansi Gupta et al./ Structural Integrity Procedia 00 (2025) 000 – 000

throughout the span with atoms at extreme corners having similar displacements. It can be inferred that the CSH gel at nanoscale, acts a single unit and macroscale bending behaviour can be replicated even at this scale. The displacement contour highlights the structural response of the CSH gel to external bending forces, which is critical for understanding failure mechanisms in materials under different loading conditions. The displacement profile in z direction shows the atomic movements in the loading direction. A layered displacement pattern is observed in the z direction which is also in line with macroscopic investigations. At the later stages of loading, the overall displacement of the specimen increases. The progression of out-of-plane displacements during the bending is highlighted. The top layer experiences the deflection around 1.7 Å, while the bottom layer displaces to a maximum value of 10 Å.

Fig. 6. Displacement contour in y-direction at (a) 0 ps, (b) 600 ps, (c) 1095 ps.

The evolving atomic velocity profile of CSH gel as the bending progresses is shown in Fig. 8. Only the mobile region of CSH beam have initial velocities, it can be seen from Fig. 8 (a) that in mobile regions the oxygen and hydrogen atoms have more velocities than the calcium ions. Thus, it can be inferred that the interlayer water in CSH gel is more likely to displacement during loading resulting in formation of voids. As the loading progresses, the atoms near the notch experience higher velocities due to increased deformation or stress levels. As a result, atomic rearrangement occurs near the notch and due to the high velocities of oxygen and hydrogen atoms, these atoms are most likely to debond first as seen from the bending profile also. This observation sheds light on the possible causes of failure in CSH gel. The velocity magnitude profiles reveal that although the magnitude of velocity does not change over the course of loading; the interlayer water is significantly reduced.