Elastic Response of Open-Hole Material-Extruded PLA Plates: Equivalent Laminate Architectures and Perimeter Paths

Abstract

The elastic response of an open-hole material-extruded plate depends on both its interior raster architecture and the deposition paths around its boundaries. This study examines whether laminate preferences obtained from a homogeneous model persist when perimeter paths are represented. Six symmetric equivalent-laminate architectures were compared for polylactic acid plates at hole-diameter-to-width ratios of 0.20, 0.25, and 0.40 using plane-stress finite-element models with homogeneous interiors, tangential hole bands, and combined hole and outer bands. Mesh refinement, an independent block mesh, and layered-shell comparisons assessed numerical consistency. In the finest homogeneous comparison at a ratio of 0.25, [90/45/90] reduced the stress concentration factor by 0.90% relative to [0/0/0], while increasing displacement by approximately 2.84%. Adding hole and outer bands reversed this stress advantage, giving a 1.38% higher stress concentration for [90/45/90]. Across the complete perimeter-model screen, [0/0/0] gave both the lowest stress concentration and the lowest displacement, eliminating the preference-dependent trade-off found in the homogeneous models. Comparison with published tensile curves gave elastic-slope discrepancies of 0.5–3.9% for the primary material dataset and 13.2–16.0% for the experimental source’s constants; this literature-based benchmark is limited to global elastic response and does not validate local hole-edge stresses, failure loads, or laminate ranking. Perimeter paths can therefore determine the preferred elastic architecture even when the interior material exhibits only weak orthotropy.