Buckling and postbuckling of soft-core sandwich plates with composite facesheets

Finite element analysis is conducted to investigate the effect of coupling between the stiff facesheets and the flexible core on the stability of sand wich plates. The facesheets and the core are treated separately as three-di mensional solids. Initially, linear buckling analysis was carried out to de termine the buckling loads for a wide range of the facesheet stiffness and core stiffness. Numerical results indicate that, for sandwich plates with a soft core such as PVC foam, the model that smears the facesheets and core overestimates the initial buckling load, demonstrating the importance of tr eating the facesheets and the core separately. Subsequently, postbuckling a nalysis was carried out. Numerical results show that, for sandwich plates w ith a soft core, the postbuckling behavior is unstable in that static equil ibrium cannot be maintained once the buckling initiates. To examine buckling and postbuckling behavior of sandwich plates with soft cores such as PVC foam, the finite element method is used for numerical ana lysis. In the present work, the facesheets and the core are modeled separat ely as three-dimensional solids. For this, three or four elements are used through the plate thickness with a single element for the each facesheets a nd one or two elements for the core. The linear buckling analysis is conduc ted to determine the initial buckling load. Subsequently, a geometrically n onlinear analysis with branch switching and the are-length method is used t o examine the postbuckling behavior (Huang 1994; Kouhia 1981; Riks 1972). C ore plasticity is not included and only global buckling is considered.