An isogeometric continuum shell element for non-linear analysis

An isogeometric continuum shell formulation is proposed in which NURBS basis functions are used to construct the reference surface of the shell. Through-the-thickness behavior is interpolated using a higher-order B-spline which is in contrast to the standard continuum shell (solid-like shell) formulation where a linear Lagrange shape function is typically used in the thickness direction. The present formulation yields a complete isogeometric representation of the continuum shell. The shell element is implemented in a standard finite element code using Bézier extraction which facilitates numerical integration on the reference surface of the shell. Through-the-thickness integration is done using a connectivity array which determines the support of a B-spline basis function over an element. The formulation has been verified using different linear and geometrically non-linear examples. The ability of the formulation in modelling buckling of static delaminations in composite materials is also demonstrated.