Mechanical characterization and numerical evaluation of auxetic and honeycomb sandwich panels manufactured by masked stereolithography

This study evaluates the structural performance of polymer-based sandwich panels fabricated via masked stereolithography (mSLA), focusing on the mechanical response of auxetic core geometries under quasi-static loading. Two distinct core topologies—honeycomb and re-entrant—were additively manufactured and embedded within beam-type sandwich structures to evaluate their flexural behavior. The influence of core placement was investigated by comparing internal (in-beam) and external (out-of-beam) configurations. The mechanical characterization included uniaxial tensile testing and three-point bending experiments. The printed resin samples demonstrated an average tensile strength of 51 MPa and a Young’s modulus of 3 GPa. Under bending, re-entrant in-beam structures exhibited a more uniform stress distribution and improved deformation resistance, reaching a peak stress of 57 MPa. Honeycomb out-of-beam structures showed higher localized stress, indicating sensitivity to core orientation. Finite element analysis (FEA) conducted using Abaqus correlated well with experimental data, with discrepancies within 10% for in-beam configurations. These results highlight the potential of mSLA-fabricated auxetic structures for lightweight, load-bearing applications. The study confirms that mechanical performance can be tuned by modifying core topology, ligament arrangement, and positional configuration within the sandwich panel, offering design flexibility for advanced structural components in additive manufacturing.