Nonlinear in-plane buckling of 3D-printed sandwich shallow arch metastructures with carbon fiber reinforced polylactic acid composite layers

Meta-sandwich structures, designed to address the growing demand for lightweight yet high-performance materials, have gained significant attention for their versatile applications across diverse industries. This study focuses on analyzing the nonlinear in-plane buckling behavior of meta-architected sandwich shallow arches. The investigated meta-sandwich arch consists of a pure polylactic acid (PLA) auxetic core and continuous carbon fiber reinforced (CCFR) PLA composite layers. The arch is subjected to a central concentrated force and examined under different boundary conditions. The experimental work comprised tensile tests on 3D-printed dogbone coupons to determine their mechanical properties, alongside digital image correlation for detailed strain analysis. Additionally, scanning electron microscopy is employed to assess the 3D printing quality, examine filament adhesion, and investigate the interaction between fibers and the polymer matrix. The governing equations are formulated using first-order shear deformation theory alongside von-Kármán geometric nonlinearity, employing the virtual displacement principle. These nonlinear equations are subsequently solved using the Ritz and cylindrical arc-length methods. In addition, the experimental mechanical properties of the CCFR-PLA composite are further verified by constructing a representative volume element and performing finite element analysis within the Abaqus solver environment. Following validation against established findings, a parametric study is conducted to explore the influence of various parameters on the nonlinear snap-through instability responses of the sandwich arch metastructures.