PSI - Issue 60

Rakesh Bhadra et al. / Procedia Structural Integrity 60 (2024) 149–164 Bhadra et al. / Structural Integrity Procedia 00 (2023) 000 – 000

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MPa).

Figs.10.(a) and (b) show the residual von Mises stress distribution over the nanocomposite with the variation of gradation parameter at the end of the unloading stage. The figure clearly shows that the residual stress distribution value is higher for the high value of the gradation parameter, similar to the end of the loading stage. As the gradation parameter increases, the stiffness of the material increases. The higher value of residual von Mises stresses indicates that a higher amount of plastic deformation or permanent deformation takes place at the end of the unloading stage. This will discuss in the preceding section.

(a)

(b)

(c) Fig.11. Stress-state contour plot of the near-contact zone comparing von-Mises stress to yield stress corresponding to indentation depth of 0.78 nm: (a) γ e = +2, (b) γ e = 0, and (c) γ e = -2 nm (CNTs wall thickness constant). Figs.11.(a) to (c) display stress state contour plots of CNTs based elastic graded nanocomposite. These plots provide a comparison between von Mises stress and yield at any point within the nanocomposite at the end of the loading stage. Additionally, the contour plots show the plastic and post-plastic phases. It is observed that the volume of plastically deformed material is higher for a higher value of the gradation parameter, while a lower gradation parameter results in a lower volume of plastic deformation. Consequently, a greater amount of energy dissipation occurs when the gradation parameter is high due to the larger volume of plastically yielded material. Furthermore, the recovery of deformation is lower for higher gradation parameter values, which implies that a higher gradation parameter leads to a reduced ability of the material to recover from deformation. 3.3.2 Analysis of Deformation This section focuses on the analysis of the deformation behavior of functionally graded CNT-based nanocomposite (FG-CNT). An essential aspect of understanding contact behavior is examining the nodal displacement of the nodes situated at the contacting surface in both the x and y directions. Subsequently, the nodal