Flexural energy and deformation of 3d-printed hybrid sandwich structures: an experimental and numerical study

Abstract The challenge in the design of sandwich structures is that structural designs should be suitable for manufacturing across a variety of materials with higher energy absorption (EA) and minimum weight. Four hybrid sandwich structures (capsule-T-hexagon, capsule-T-circle, capsule-arrow, and capsule-plus) were designed in this study. The length and height of all five unit cells are the same, and the structural shape is only different, and they are manufactured in fused deposition modeling method using PLA, PLA/CF (20%), and polyethylene terephthalate glycol (PETG) materials. Flexural strength, EA, and specific EA (SEA) were evaluated by three-point bending on twelve sandwich structures. The capsule-T-hexagon hybrid sandwich structures with PLA material exhibit a maximum flexural strength of 17.77 MPa and with PETG possess maximum EA of 20.67 J. The capsule-arrow sandwich structures show maximum SEA of 43.84 J kg −1 in PLA/CF and also in PETG with maximum SEA of 142.6 J kg −1 . The Arrow and T-hexagon demonstrated superior EA through stable progressive deformation, whereas Plus and T-circle suffered premature instability, leading to reduced EA. A hybrid EA characteristic in the sandwich structures was recorded when they were heterogeneously configured using the capsule unit cell. The findings reveal the performance depends on both section modulus and progressive deformation mode. The capsule-arrow hybrid exhibit 5% higher SEA in PLA/CF and 3.5% higher in PETG compared to the capsule-T-hexagon. The flexural stiffness and flexural modulus results were validated through numerical simulation using a plasticity material model (bilinear isotropic hardening) in ANSYS Workbench 2023 R1. The validated model predicts structural behavior, aiding the design of lightweight sandwich panels in automotive and unmanned aerial vehicle applications.