PSI - Issue 38

A. Cugniere et al. / Procedia Structural Integrity 38 (2022) 168–181 A. Cugniere, O. Tusch and A. Mösenbacher / Structural Integrity Procedia 00 (2021) 000 – 000

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The distribution of von Mises equivalent strains along the structure was calculated for both the initial state (without crack) and a damaged state (with a 10mm-long synthetic crack), as can be seen in figure 15:

Fig. 15. Distribution of von Mises equivalent strains for undamaged and damaged states

Using the strain distribution of the damaged structure as design constraints, an optimization was performed on the undamaged structure. The optimization is carried out using Nastran SOL200, choosing an adjoint-method (as opposed to a direct-method) for the sensitivity analysis. The thickness of every 2D-shell element of the undamaged structure was defined as design variable. The goal was to see whether the optimizer could retrieve the position of the synthetic crack. Figure 16 shows the results of the optimization, compared to the expected results:

Fig. 16. Results of the topometry optimization vs. expected results

The optimizer chooses to minimize the thickness of the elements that roughly match the position of the synthetic crack (red = thickness unchanged, yellow = thickness reduced). Therefore, the approach can be seen as valid, with high potential in other applications.