One of the benefits of composite structures is the ability to make complex thin shapes. However, the disadvantage of thin wall thickness is disproportionately poor out-of-plane stiffness. Cores provide out-of-plane bending stiffness, increasing the stability, shape, stiffness and strength by creating a structural sandwich. The lightweight core also provides much of the shear rigidity and can dramatically increase the ratio of stiffness to weight.
Cores are lightweight, low density materials often with a cellular construction. Honeycomb-like core formed of a thin material or a corrugated sheet material (such as aluminium, Nomex, or polypropylene). In addition synthetic foam cores are also effective and in some applications the natural balsa wood shows significant advantage. Consequently, design methods have to account for core shear deformation because of the low effective shear modulus of the core. Test procedures have to determine the effects of core shear properties on deflection, buckling, crimping and stress for the composite sandwich.
Engenuity has wide experience of analysing, specifying and recommending appropriate cores for new products and components. We can take a manufacturer’s core properties and incorporate them into analysis for a customer’s part to design and develop the product to work against the load cases.
Cores come in many forms and Engenuity has analysed intrusion to the side of a Formula One chassis; seat belt attachments; fuel tank integrity; boat hull performance; and aircraft floors.
Engenuity uses advanced FEA software to determine core sheer stress through thickness compressive and tensile stress for numerous clients nationally and internationally.