PSI - Issue 37

Shirsha Bose et al. / Procedia Structural Integrity 37 (2022) 131–138 Bose et al., 2021/ Structural Integrity Procedia 00 (2019) 000 – 000

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cases along the centres (Fig. 3c) and edges (Fig. 3d) are also plotted. The maximum levels of stresses were generated along the direction of applied strain at the island edge (AD).

Fig. 2: Boundary conditions and loading directions for square and circular micro-islands.

For the metallic layers, the maximum stress generated for the gold layers were lower by approximately 50% than its yield strength (230 MPa) for both geometries; while the chromium layer reached its yield point of 160 MPa, with the square geometry slightly exceeding it (denoted in grey in Fig. 3b). This is an indication of the onset of plastic deformation, which might lead to poorer performance of the square structures as compared to the circular ones. The edges and central lines of the collagen substrate showed higher levels of stress accumulation for square micro islands (in the loading direction on AD) as compared the circular ones (on AC) (Fig. 3c). Contrarily, the difference in the stress generation on the central lines for both micro-islands were relatively insignificant (Fig. 3d). The lower levels of stress generation in both metallic layers and the collagen substrate for the circular geometry implies that these structures would perform better.