Issue 75

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

(a) (b) Figure 26: Structural weight evolution of (a) E2-OP1 and (b) E2-OP3, highlighting the best and worst performing runs among 5 independent optimization processes. The shaded area represents the distribution of the remaining runs.

(a) (b) Figure 27: Complementary strain energy evolution of (a) E2-OP1 and (b) E2-OP3, highlighting the best and worst performing runs among 5 independent optimization processes. The shaded area represents the distribution of the remaining runs. For the attained load levels evaluated at the best-fitness designs, both E2-OP1 and E2-OP2 reach the prescribed target 0 P in all runs. Consequently, the proposed framework reliably achieves the required load-bearing capacity under the stated conditions.

(a) (b) Figure 28: Load-baring evolution of (a) E2-OP1 and (b) E2-OP3, highlighting the best and worst performing runs among 5 independent optimization processes. The shaded area represents the distribution of the remaining runs. In the case of the critical buckling load factors, Fig. 29 shows that, compared to the previous 37-bar example, generally lower values were obtained. Nevertheless, for all best-performing solutions based on fitness across the individual runs— including both E2-OP1 and E2-OP2—the proposed framework achieved critical buckling load factors  ˉ exceeding the predefined stability threshold of 1.000 stab   . As observed in Figs. 25–29, both optimization setups, E2-OP1 and E2-OP2, yielded similar fitness values and corresponding structural properties, as further detailed in Tab. 10. Remarkably, all final solutions satisfied the structural criteria enforced through the penalty functions: the complementary strain energy of residual forces p W remained below the

151