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This research investigates the influence of material properties in additively manufactured, fully elastic models produced with 3D printing, with a focus on mitigating these effects in the design process. The study emphasizes the orthotropic and frequency-dependent behavior of 3D-printed PETG material and the impact of an epoxy coating required for waterproofing.

Experimental testing was conducted using thin-walled specimens printed in three principal directions. Designed to capture torsional and bending responses, the specimens underwent shaker tests in weighted and unweighted configurations. While the weighted setup extended the measurable frequency range, it introduced inconsistencies in eigenfrequencies, leading to reliance on unweighted shear test data for further analysis despite associated errors.

These material properties informed a numerical model divided into orthotropic and laminated sections, with laminate theory applied to transverse structures and orthotropic properties assigned to longitudinal walls. The effect of an epoxy layer and water interaction was incorporated through boundary element analysis, generating hydrodynamic stiffness and added mass matrices.

The results highlight the dominant influence of the transverse Young’s modulus, 𝐸1 , on eigenfrequencies, particularly in bulkheads and plating, while 𝐸3​ primarily affected higher modes. The epoxy coating increased eigenfrequencies by 2.6%, while frequency dependence contributed minimally to variations. To minimize epoxy influence, thinner coatings or alternative waterproofing methods are recommended. Addressing orthotropic behavior may require refined printing settings for isotropic properties or scaling strategies prioritizing
𝐸1​ .

These findings provide valuable insights for designing 3D-printed elastic models with improved dynamic response and reduced material property effects.