Large Deflection Behavior Analysis Of Circular Sandwich Plates With Metallic Cores

Energy absorbing and higher strength-to-weight ratio of sandwich structure than conventional monolithic constructions make it used in many critical areas of engineering, such as ship, aircraft, automotive and aerospace industries. Generally, a sandwich plate always consists of two thin face-sheets adhered to a thick metallic foam core which is a typical lightweight structure. The face-sheets carry nearly all of longitudinal loads and bending moments while the core resists shear loads mainly. As research progressed, the research of mainly mechanical properties of sandwich structures include the load-carrying capacity, deformation failure mechanism and plastic energy dissipation gradually highlight. However, the most analyses were based on the assumption of a small deflection and few papers on large deflection behavior of sandwich structure.The major aim of this paper is to extend the ‘equal area method’ of Calladine to sandwich structure, as the approach has been well established for monolithic circular plates. And the analytical solution of each stage for both simply supported and fully clamped sandwich structure under transverse quasi-static point central loading has been deduced. To validate the analytical solution, a finite element simulation is performed. A parametric study is then carried out to examine the effects of the boundary conditions, core strength and face/core thickness ratio on the structural response. And the results are as follows:(1) Agreement is really good for the plastic plateau strength for the simply supported case, and for the post-yield region of the clamped case for the finite deflection model.(2) The core thickness is a considerable influence on the load-deflection behavior in both the loading conditions. For the simply supported plates, the larger core thickness is, the smaller gap between relevant curves is. That observation indicates the face yield is the main mechanism after the initial collapse. On the other hand, the fully clamped plates show that it is reasonable to neglect the effect of radial stress due to the existence of the plastic hinge. And the face-sheets carry nearly all the normal stress when the plates begin to deform.(3) The smaller radius of central punch leads the less error between the theoretical analysis and numeric simulation, the explanation of which is that in Equal area method theoretical analysis center load P is treated as a point load for simplicity. Thus, the size of punch is the one reason for the discrepancy of curves.