Modeling of pin-facesheet interactions in k-cor sandwich structures under compressive loading

Abstract

Pin reinforced foam cores with composite facesheets offer a viable means of structural construction owing to their low weight and high stiffness and strength. In this paper, various models are introduced to estimate the stiffness and strengths of such a sandwich structure, called K-Cor™, under out-of-plane compressive loading conditions. ince the reinforcing pins have a high modulus compared to the modulus of the facesheet in the transverse direction, the pins indent into the facesheets affecting the overall compressive stiffness of the sandwich structures. Models incorporating this interaction are constructed and their compressive properties are compared with experimental results for various sandwich specimens. The effect of pin locations and size of the sandwich on its compressive properties is also investigated. Nomenclature= Cross sectional area of facesheet = Cell spacing = Young's modulus of pin = Core stiffness = Modulus of facesheet = Stiffness of the sandwich structure = Core stiffness of infinite panel = Spring constant of model 2 = Spring constant of model 3 = Core thickness = Facesheet thickness = Thickness of the sandwich structure = Pin spring constant = Spring constant of core = Spring constant of facesheet = Spring constant of the sandwich structure = Interaction spring constant of a spring attached to a single pin = Interaction spring constant of the spring for entire core = Compressive spring constant of a single pin model = Number of active pins in the structures

Delamination resistance of composite laminated structures reinforced with angled, threaded, and anchored Z-pins

“…When the Z-pin is inserted with an angle, mechanical interlocking can significantly increase in addition to the contact area of Z-pin with the laminate. Angled Z-pins have been considered for composite sandwich structures to increase shear and compressive properties of the foam core 22 and laminated structures under shear loading. 23 Subsequently, we examine a novel variety of pin, namely the threaded pin, as a candidate for reinforcement of composite laminates via increase in mechanical interlocking.…”