Experimental and Numerical Studies on Core Stiffened Sandwich Composite Panel

The experimental and numerical studies of carbon composite sandwich panels with stiffened polyurethane (PU) foam core were carried out. A novel concept of stiffening the panels by co-bonding to skin was introduced. The stiffening of PU core was conceptualized using carbon composite by wrapping and skin/facesheet was co-bonded. Four different sandwich panel configurations such as plain, longitudinal stiffening, transverse stiffening, and stiffening in both directions were manufactured. To explore the suitability of this novel concept for structural applications, the bending behavior of panels were investigated under three-point bend tests. A three-dimensional finite element model incorporating stiffness degradation concept was developed in ANSYS to understand the fundamental behavior of configured panels. Experimental and numerical results showed failure patterns like shear in foam core, indentation in composite skin and bulge/lift-off of outer composite stiffener. Comparative study of results showed that oriented stiffened sandwich panels have superior mechanical characteristics with 75% increase in the load-bearing capacity and 29% reduction in displacement. The failure patterns were envisaged through microscopy and computer-based tomography techniques.