Experimental and numerical investigation of sandwich structures with balsa core and hybrid corrugated composite/balsa core under three-point bending using digital image correlation

Sandwich structures are commonly used in automotive, aerospace, and civil infrastructure applications due to their high strength-to-weight and stiffness-to-weight ratios. In the present work, the performance of sandwich structures with aluminum facings and two different types of core, including balsa wood core and hybrid corrugated composite/balsa core subjected to three-point bending, is investigated, both experimentally and numerically. The face sheets are 6061-T6 aluminum alloy and the hybrid core has been made of balsa wood with average density of 125 kg m ⁻³ and E-glass woven fabric, bonded together using epoxy resin. For data acquisition during the tests, a linear variable differential transformer has been placed under the mid-span of the specimens and a digital image correlation technique has been used for monitoring the full-field strain distributions and deflection pattern as well. Continuum damage mechanics has been employed for the finite element model analysis of the three-point bending tests. In order to predict the maximum load-bearing capacity and failure modes, a wood material behavior model for balsa and a combination of Hashin and Puck failure criterion for corrugated composite were imported into ABAQUS/Explicit via VUMAT subroutines. It was found that combining balsa core with corrugated composite results in prevention of catastrophic failure and consequently gradual decrease of load-bearing capacity. Furthermore, the results demonstrate that the hybrid core increases the strength-to-mass density and stiffness-to-mass density ratios by 34.7% and 28.2%, respectively. Numerical findings have been successfully compared to experimental data, which reveals its suitability for parametric analysis of the proposed hybrid core sandwich structure.