Buckling design of stiffened sheet-based inner core based on bifurcation analysis

• The critical load of the column with a varying cross-section is derived.
• Buckling mode about the stiffened core depend on the aspect ratio.
• Increasing the arc angle increases the critical load under global buckling.
• Increasing the stiffened length increases the critical load under global buckling.
• The stiffened length affects more than the arc angle below global buckling.

In the structural design of the sandwich plate, the inner core plays a key role to have its maximum performance. A shaped pyramidal truss core is proposed in order to increase the strength and productivity of the sandwich core. In this paper, the design guidelines of the shaped pyramidal truss core, which is enhanced by forming a cross-section of an arc shape at the strut of the inner core, is described. The inner core is composed of a stiffened section and a transient section with a varying cross-section. The critical load for bifurcation in compressive instability is calculated using an analytical and FEM simulation. The analytical equation for the critical load of the shaped column is derived using the energy method. The various buckling modes (global, distortional, local) occur due to these effects. Therefore, complications induced by such effects must be taken into account in the design. Parametric studies for the stiffened core are conducted. The effect of geometric parameters is investigated for optimal design of the inner core and their influence have been discussed.