Failure mode analysis of cylindrical sandwich shells with truss core considering shell/core debonding under bending/compressive loading

The gap in the literature lies in the limited understanding of the mechanical behavior of cylindrical sandwich shells with truss cores (CSSTC), particularly under uniaxial compression and bending loads, and the critical role of shell/core debonding. This study presents a novel finite element-based investigation into the failure mechanisms of cylindrical sandwich shells with truss cores (CSSTCs), emphasizing shell/core debonding under combined bending and compressive loads. Unlike previous studies that commonly assume perfect bonding, this research introduces an innovative adhesive layer between the face sheets and the core, modeled using a cohesive surface contact approach to capture debonding initiation and progression. The novelty of this work lies in systematically evaluating how adhesive stiffness influences critical loads, buckling behavior, and overall structural integrity, offering a realistic simulation of partial bonding conditions. This study numerically investigates the bending and compressive failure modes of cylindrical sandwich shells with truss cores (CSSTCs), considering shell/core debonding. Finite element simulations using ABAQUS software were conducted to analyze buckling modes and critical damage forces. Key factors such as element shape and meshing techniques were evaluated to ensure accurate modeling. A novel method was developed to enhance critical load capacity by integrating an innovative adhesive layer between the cylindrical shells (CSs) and the core, aiming to achieve structural robustness comparable to fully bonded configurations. Aluminum was used as the core and face sheet material in the detailed modeling of sandwich structures. The study employed cohesive surface contact to simulate debonding in the numerical models. Mesh convergence analysis demonstrated the significant influence of mesh orientation and element shape on modeling accuracy and convergence rates. Numerical results revealed buckling modes and critical loads for cylindrical shells and sandwich structures under various loading conditions. Furthermore, the study examined the effect of adhesive stiffness on critical moments during pure bending, highlighting its crucial role in structural performance.