PSI - Issue 77

Kumar C. Jois et al. / Procedia Structural Integrity 77 (2026) 405–412 Jois, et al./ Structural Integrity Procedia 00 (2026) 000–000

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(a)

(b)

H1 (~30 ° )

J1 (~30 ° )

G1 (~45 ° )

Fig. 4. (a) Void angle distribution; (b) Void density along the thickness.

A second void pattern, illustrated in Fig. 4 (b), shows a gradual increase in void count, followed by a slight decrease. This trend is likely caused by progressive compaction during winding. Lower layers experience greater compression from subsequent layers, reducing available void space, while upper layers undergo less compaction, allowing more voids to persist. The mid-section experiences partial compaction, where trapped voids are unable to escape during consolidation. This mechanism is believed to account for intralaminar voids within the laminate. 3.2. Numerical analysis results Fig. 5 presents the damage variable contour plots for four cases: ideal bonding, cohesive interaction, 3% void content, and 6% void content. The inclusion of cohesive interactions leads to higher local stresses, offering a more realistic representation of interfacial behavior compared to the ideal bonding model. However, no significant difference in overall stress patterns was observed between the models with 3% and 6% void distributions. It is observed that the damage variable is significantly elevated at the boss interface, which is likely attributed to the complex stress interactions and increased composite thickness in the turnaround regions. Based on empirical evidence, stresses in this region are typically reduced by approximately 50% to account for these effects. The predicted burst region, indicated by the circle in the contour plot, aligns well with the failure locations predicted in Fig. 5, confirming consistency between the modelling approaches.