PSI - Issue 66

Mansi Gupta et al. / Procedia Structural Integrity 66 (2024) 122–134 Mansi Gupta et al. / Structural Integrity Procedia 00 (2025) 000 – 000

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All the MD simulations are conducted on Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) [Thompson et al. (2022)] at high-performance computing (HPC) cluster (model No: HP DL360p). The post-processing of results is done using Open Visualization Tool (OVITO) [Stukowski et al. (2009)] and MATLAB (2012).

Fig. 2. CSH beam model with notch.

For the three-point bend tests, the simulated cell is divided into set of mobile and rigid regions. The end atoms of the CSH beam nanostructure are fixed for a distance of 30 Å on both side and rest of the atoms are free to move. A load of 0.15 pN is applied on the middle 50 Å region to simulate the centre-point bending with non-periodic boundary conditions. The loading details are schematically represented in Fig. 3.

Fig. 3. Schematic representation of loading setup.

5. Results The CSH gel deforms under three-point bending as the simulation progresses. The deformation profiles for the CSH beam under bending at different time steps is shown in Fig. 4. Fig. 4 (a)-(g) shows the bending profiles at 0 ps, 250 ps, 500 ps, 600 ps, 750 ps, 1000 ps, and 1095 ps. Due to computational restrictions, the simulation is aborted after a time period of 1095 ps. The effect of bending is clearly visible in the displacement profiles. As the loading progresses, the crack opening displacement increases. However due to continuous atomic reactions, a sharp crack in not observed in the CSH gel. The atomic investigations reveal that the oxygen and hydrogen bonds are primarily responsible for the crack widening. The continuous bonding and debonding of oxygen and hydrogen atoms is observed throughout the loading stage. This causes energy dissipation in atoms resulting in overall softening