Curvature-Waviness Interaction in Self-Locking Honeycombs: Contact-Driven Compression and Progressive Compaction.

Self-locking honeycombs exploit intercellular contact to regulate deformation and load transfer during compression, yet the coupled effects of wall curvature and 3D contact morphology remain insufficiently understood. The present work develops a two-parameter geometric framework in which the in-plane curvature angle (α) and through-height waviness index (m) independently control the morphology of curved walls that simultaneously carry load and provide intercellular contact. Twelve additively manufactured PA12 self-locking assemblies were investigated by frameless quasi-static compression and nonlinear finite-element simulations. Increasing wall waviness generally enhanced initial stiffness and peak resistance, whereas the influence of curvature angle was non-monotonic. The configuration with m=3, α=60° achieved the highest mean mass-normalized peak force of 17.11 N/g, while m=3, α=45° provided the highest mean specific energy absorption of 0.59 J/g and crush force efficiency of 0.78 at 45% strain. Deformation observations and simulations indicate that stable progressive compaction requires sufficient intercellular engagement while preserving the sliding, rotation, recontact, and compatible void closure needed for continued deformation. Excessive geometric constraint can instead promote row misalignment and interrupted compaction. The framework provides a design basis for lightweight energy-absorbing cores in protective panels, transportation crash management structures, and packaging systems, subject to future dynamic validation.