Issue 75

P. Grubits et alii, Fracture and Structural Integrity, 75 (2026) 124-156; DOI: 10.3221/IGF-ESIS.75.10

Figure 5: Second stage of the developed framework.

3. Establishing geometrical imperfections and determining the critical buckling load factor via LBA: A linear buckling analysis (LBA) is performed for each individual to extract the eigenvalues j  and the corresponding mode shapes j  , which are used to define the initial geometric imperfection  x . These imperfections are introduced in accordance with the design setup, ensuring consistency with the selected imperfection strategy, as illustrated in Fig. 6. In addition, the critical buckling load factor  is identified and subsequently employed in the calculation of the stability-related penalty term   2 p  which quantifies sensitivity to global instability and penalizes geometrically vulnerable configurations.

Figure 6: Third stage of the developed framework.

Figure 7: Fourth stage of the developed framework. 4. Calculating fitness value according to the design scenario: A geometrically and materially nonlinear analysis (GMNA) is carried out to simulate the full structural response under the applied loading history. When a displacement constraint is imposed, the analysis is terminated upon reaching the predefined limit max U at the designated reference point, and the corresponding mechanical response values are extracted. Plastic deformations are quantified in the form of the accumulated complementary strain energy of residual forces, p W . Depending on the design scenario, the penalty terms

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