Comparative Study of Core Material's Stiffness on Sandwich Panel with Composite Face Sheets beyond the Yield Point

The study aims to explore the performance of sandwich panels exceeding the yield point stiffness of the core material. Sandwich panels have gained growing attention among designers owing to their excellent corrosion properties, and lightweight, and speedy installation process. They have been applied in numerous industrial sectors, including aerospace, architectural, marine, and transportation. Typically, sandwich panels are composed of a single central core sandwiched by a pair of outer face sheets, where the core is normally developed using softer materials compared to the face sheets. Given that past studies have primarily focused on sandwich panels in the elastic range, this present study explored the performance of sandwich panels exceeding the yield point stiffness of the core material. The univariate search optimization method was utilized to assess the elastic modulus ratio of the core (typically foam) to the face sheet (composite material). The load was elevated in a quasi-static order until the face sheets reached their yield point. Subsequently, the panel was simulated using the finite element analysis commercial package ANSYS APDL, with simply supported boundary conditions used on all sides of the panel. The proposed model was verified by comparing the numerical and experimental data from recent literature. Based on the results, the panel's increased load-carrying capacity corresponded as the core material stiffness exceeded its yield limit. Moreover, the transmission of load to the face sheets increased as the core stiffness decreased. In summary, stiffer core materials caused the sandwich panel to behave more as isotopic face sheets. Thus, the face sheets yielded ahead of the core material.